U.S. patent application number 17/592672 was filed with the patent office on 2022-08-25 for battery and current collector applied thereto, and battery pack and vehicle including the battery.
This patent application is currently assigned to LG ENERGY SOLUTION, LTD.. The applicant listed for this patent is LG ENERGY SOLUTION, LTD.. Invention is credited to Yu-Sung CHOE, Kyu-Hyun CHOI, Su-Ji CHOI, Kwang-Su HWANGBO, Min-Ki JO, Ji-Min JUNG, Bo-Hyun KANG, Do-Gyun KIM, Hak-Kyun KIM, Jae-Woong KIM, Jin-Hak KONG, Byoung-Gu LEE, Jae-Eun LEE, Je-Jun LEE, Kwan-Hee LEE, Soon-O LEE, Hae-Jin LIM, Jae-Won LIM, Geon-Woo MIN, Jong-Sik PARK, Pil-Kyu PARK, Duk-Hyun RYU.
Application Number | 20220271403 17/592672 |
Document ID | / |
Family ID | |
Filed Date | 2022-08-25 |
United States Patent
Application |
20220271403 |
Kind Code |
A1 |
LIM; Jae-Won ; et
al. |
August 25, 2022 |
BATTERY AND CURRENT COLLECTOR APPLIED THERETO, AND BATTERY PACK AND
VEHICLE INCLUDING THE BATTERY
Abstract
A battery includes an electrode assembly including a first
electrode, a second electrode, and a separator between the first
electrode and second electrode, a first portion including an active
material extending between a pair of first sides, and a second
portion extending between the pair of first sides and exposed
beyond the separator, at least a part of the second portion
includes an electrode tab; a battery housing having a first end
with a first opening, a second end opposite the first end, and an
inner surface, the battery housing accommodating the electrode
assembly; a first current collector including a tab coupling
portion coupled to the second portion of the first electrode and a
housing coupling portion extending from the tab coupling portion
and electrically coupled to the inner surface of the battery
housing; and a cap covering the first opening of the battery
housing.
Inventors: |
LIM; Jae-Won; (Daejeon,
KR) ; KIM; Hak-Kyun; (Daejeon, KR) ; LEE;
Je-Jun; (Daejeon, KR) ; JUNG; Ji-Min;
(Daejeon, KR) ; HWANGBO; Kwang-Su; (Daejeon,
KR) ; KIM; Do-Gyun; (Daejeon, KR) ; MIN;
Geon-Woo; (Daejeon, KR) ; LIM; Hae-Jin;
(Daejeon, KR) ; JO; Min-Ki; (Daejeon, KR) ;
CHOI; Su-Ji; (Daejeon, KR) ; KIM; Jae-Woong;
(Daejeon, KR) ; PARK; Jong-Sik; (Daejeon, KR)
; CHOE; Yu-Sung; (Daejeon, KR) ; LEE;
Byoung-Gu; (Daejeon, KR) ; RYU; Duk-Hyun;
(Daejeon, KR) ; LEE; Kwan-Hee; (Daejeon, KR)
; LEE; Jae-Eun; (Daejeon, KR) ; KANG; Bo-Hyun;
(Daejeon, KR) ; KONG; Jin-Hak; (Daejeon, KR)
; LEE; Soon-O; (Daejeon, KR) ; CHOI; Kyu-Hyun;
(Daejeon, KR) ; PARK; Pil-Kyu; (Daejeon,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LG ENERGY SOLUTION, LTD. |
Seoul |
|
KR |
|
|
Assignee: |
LG ENERGY SOLUTION, LTD.
Seoul
KR
|
Appl. No.: |
17/592672 |
Filed: |
February 4, 2022 |
International
Class: |
H01M 50/536 20060101
H01M050/536; H01M 50/107 20060101 H01M050/107; H01M 50/533 20060101
H01M050/533; H01M 4/64 20060101 H01M004/64; H01M 50/507 20060101
H01M050/507; H01M 10/0587 20060101 H01M010/0587; H01M 50/152
20060101 H01M050/152 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 19, 2021 |
KR |
10-2021-0022881 |
Feb 19, 2021 |
KR |
10-2021-0022891 |
Feb 19, 2021 |
KR |
10-2021-0022894 |
Feb 19, 2021 |
KR |
10-2021-0022897 |
Feb 23, 2021 |
KR |
10-2021-0024424 |
Mar 8, 2021 |
KR |
10-2021-0030291 |
Mar 8, 2021 |
KR |
10-2021-0030300 |
Apr 9, 2021 |
KR |
10-2021-0046798 |
May 4, 2021 |
KR |
10-2021-0058183 |
Jun 14, 2021 |
KR |
10-2021-0077046 |
Jun 28, 2021 |
KR |
10-2021-0084326 |
Oct 1, 2021 |
KR |
10-2021-0131205 |
Oct 1, 2021 |
KR |
10-2021-0131207 |
Oct 1, 2021 |
KR |
10-2021-0131208 |
Oct 1, 2021 |
KR |
10-2021-0131215 |
Oct 1, 2021 |
KR |
10-2021-0131225 |
Oct 14, 2021 |
KR |
10-2021-0137001 |
Oct 15, 2021 |
KR |
10-2021-0137856 |
Oct 22, 2021 |
KR |
10-2021-0142196 |
Nov 9, 2021 |
KR |
10-2021-0153472 |
Nov 19, 2021 |
KR |
10-2021-0160823 |
Nov 24, 2021 |
KR |
10-2021-0163809 |
Nov 26, 2021 |
KR |
10-2021-0165866 |
Dec 3, 2021 |
KR |
10-2021-0172446 |
Dec 10, 2021 |
KR |
10-2021-0177091 |
Dec 31, 2021 |
KR |
10-2021-0194572 |
Dec 31, 2021 |
KR |
10-2021-0194593 |
Dec 31, 2021 |
KR |
10-2021-0194610 |
Dec 31, 2021 |
KR |
10-2021-0194611 |
Dec 31, 2021 |
KR |
10-2021-0194612 |
Jan 5, 2022 |
KR |
10-2022-0001802 |
Claims
1. A battery comprising: an electrode assembly including a first
electrode, a second electrode, and a separator between the first
electrode and second electrode, wherein the first electrode, the
second electrode, and the separator are wound about an axis,
wherein the first electrode has a pair of first sides and a pair of
second sides extending between the pair of first sides, a first
portion including an active material extending between the pair of
first sides, and a second portion extending between the pair of
first sides and exposed beyond the separator, wherein at least a
part of the second portion includes an electrode tab; a battery
housing having a first end with a first opening, a second end with
a second opening opposite the first end, and an inner surface, the
battery housing accommodating the electrode assembly through the
first opening formed at the first end; a first current collector
comprising a tab coupling portion coupled to the second portion of
the first electrode and a housing coupling portion extending from
the tab coupling portion and electrically coupled to the inner
surface of the battery housing; and a cap covering the first
opening of the battery housing.
2. The battery of claim 1, wherein the battery housing comprises a
beading portion formed on an end portion adjacent to the first
opening at the first end and press-fitted inward.
3. The battery of claim 2, wherein the battery housing comprises a
crimping portion formed at a position between the first opening at
the first end and the beading portion, and extending and bent
toward the first opening.
4. The battery of claim 3, wherein the housing coupling portion is
press-fixed by the crimping portion.
5. The battery of claim 2, wherein the housing coupling portion
comprises: a contact portion coupled to the beading portion of the
battery housing; and a connecting portion to connect the tab
coupling portion to the contact portion.
6. The battery of claim 5, wherein the connecting portion is
upwardly convex based on an imaginary straight line that connects
an end portion of the contact portion to an end portion of the tab
coupling portion.
7. The battery of claim 5, wherein the connecting portion is lifted
upward above the beading portion.
8. The battery of claim 6, wherein the connecting portion comprises
at least one bent part.
9. The battery of claim 8, wherein the bent part is located over an
imaginary plane that passes through a center of the imaginary
straight line that connects the end portion of the contact portion
to the end portion of the tab coupling portion, and is parallel to
a bottom surface of the battery housing.
10. The battery of claim 8, wherein the at least one bent part is
bent at an obtuse angle so as not to overlap itself when viewed
along a longitudinal axis of the battery housing.
11. The battery of claim 8, wherein a boundary point between the
contact portion and the connecting portion is bent at an obtuse
angle.
12. The battery of claim 10, wherein an inclination of the
connecting portion is reduced stepwise or gradually toward the
beading portion.
13. The battery of claim 5, wherein an angle between the tab
coupling portion and the connecting portion ranges from 0.degree.
to 90.degree..
14. The battery of claim 5, wherein the connecting portion supports
the cap.
15. The battery of claim 5, wherein the tab coupling portion and
the contact portion are located at a same height.
16. The battery of claim 5, wherein the contact portion comprises a
flat surface coupled to a top surface of the beading portion facing
the opening portion.
17. The battery of claim 5, wherein the beading portion comprises:
a beading portion top surface located over an innermost point that
is press-fitted inward; and a beading portion bottom surface
located under the innermost point that is press-fitted inward.
18. The battery of claim 17, wherein the tab coupling portion is
located at a lower position than the beading portion bottom
surface.
19. The battery of claim 17, wherein at least one of the beading
portion top surface and the beading portion bottom surface is
inclined at a certain angle with respect to a bottom surface of the
battery housing.
20. The battery of claim 19, wherein the contact portion is mounted
on an inclined top surface of the beading portion.
21. The battery of claim 17, wherein at least one of the beading
portion top surface and the beading portion bottom surface is
parallel to a bottom surface of the battery housing in at least a
region.
22. The battery of claim 17, wherein the beading portion top
surface and the beading portion bottom surface are asymmetric with
respect to an imaginary reference plane that passes through the
innermost point of the beading portion to be parallel to a bottom
surface of the battery housing.
23. The battery of claim 21, wherein the contact portion is mounted
on a flat top surface of the beading portion.
24. The battery of claim 2, wherein a press-fitting depth of the
beading portion PD satisfies the following formula:
PD.gtoreq.R.sub.1,min+R.sub.2,min+W.sub.bead,min wherein
R.sub.1,min is a minimum value of a radius of curvature of the
beading portion, W.sub.bead,min is a minimum value of a welding
bead width, and R.sub.2,min is a minimum value of a radius of
curvature at a boundary region between the beading portion and the
inner surface of the battery housing.
25. The battery of claim 2, wherein a press-fitting depth of the
beading portion ranges from 0.2 mm to 10 mm.
26. The battery of claim 5, wherein a press-fitting depth of the
beading portion PD and a maximum value of the press-fitting depth
PD.sub.max satisfies the following formula:
(R.sub.1,min+W.sub.bead,min)/PD.sub.max.ltoreq.OV/PD.ltoreq.(PD.sub.max-R-
.sub.2,min)/PD.sub.max wherein OV is an overlap length that is a
shortest distance from an end portion of the contact portion to a
vertical line that passes through an innermost point of the beading
portion, R.sub.1,min is a minimum value of a radius of curvature of
the beading portion, W.sub.bead,min is a minimum value of a welding
bead width, and R.sub.2,min is a minimum value of a radius of
curvature at a boundary region between the beading portion and the
inner surface of the battery housing.
27. The battery of claim 5, wherein the contact portion is welded
to the beading portion.
28. The battery of claim 21, wherein the contact portion is welded
to a flat top surface of the beading portion.
29. The battery of claim 28, wherein a welding region between the
contact portion and the beading portion is narrower than the flat
top surface of the beading portion.
30. The battery of claim 5, wherein a press-fitting depth of the
beading portion PD and a maximum value of the press-fitting depth
PD.sub.max satisfies the following formula:
(OV.sub.min-0.5*W.sub.bead,min)/PD.sub.max.ltoreq.W/PD.ltoreq.(OV.sub.max-
-0.5*W.sub.bead,min)/PD.sub.max W is a distance from an innermost
point of the beading portion to a central point of an outermost
welding bead in a radial direction, OV is an overlap length that is
a shortest distance from an end portion of the contact portion to a
vertical line that passes through the innermost point of the
beading portion, OV.sub.min is a minimum value of the overlap
length OV, OV.sub.max is a maximum value of the overlap length OV,
and W.sub.bead,min is a minimum value of a welding bead width.
31. The battery of claim 28, wherein at least one welding bead is
formed between the beading portion and the contact portion, and
wherein the at least one welding bead forms a welding pattern
having a straight line shape extending in a circumferential
direction.
32. The battery of claim 28, wherein at least one welding bead is
formed between the beading portion and the contact portion, and
wherein the at least one welding bead forms a welding pattern
having an arc shape extending in a circumferential direction.
33. The battery of claim 28, wherein a welding bead formed between
the beading portion and the contact portion forms a welding
pattern, and wherein the welding pattern has a linear shape in
which spot welding is connected.
34. The battery of claim 28, wherein a plurality of welding beads
are formed between the beading portion and the contact portion.
35. The battery of claim 28, wherein a width of a welding bead
formed between the beading portion and the contact portion is equal
to or greater than 0.1 mm.
36. The battery of claim 31, wherein the second portion of the
first electrode and the tab coupling portion are welded in a radial
direction of the electrode assembly.
37. The battery of claim 1, wherein the tab coupling portion is
welded to the second portion of the first electrode while being
parallel to a bottom surface of the battery housing.
38. The battery of claim 36, wherein a plurality of welding beads
formed between the second portion of the first electrode and the
tab coupling portion form a welding pattern having a straight line
shape extending in the radial direction of the electrode
assembly.
39. The battery of claim 36, wherein a welding bead formed between
the second portion of the first electrode and the tab coupling
portion forms a welding pattern, and wherein the welding pattern
has a linear shape in which spot welding is connected.
40. The battery of claim 36, wherein a width of a welding bead
formed between the second portion of the first electrode and the
tab coupling portion is equal to or greater than 0.1 mm.
41. The battery of claim 1, wherein at least a part of the second
portion of the first electrode comprises a plurality of segments
divided in a winding direction of the electrode assembly, and
wherein the plurality of segments are bent in a radial direction of
the electrode assembly to form a bent surface.
42. The battery of claim 41, wherein the plurality of segments
overlap in multiple layers in the radial direction of the electrode
assembly to form the bent surface, wherein the bent surface
comprises a stack number increasing section in which the number of
overlapping layers of the segments is sequentially increased to a
maximum value from an outer circumference to a core of the
electrode assembly and a stack number uniform section from a radius
point at which the number of overlapping layers is the maximum
value to a radius point at which an innermost segment exists.
43. The battery of claim 42, wherein the tab coupling portion is
coupled to the bent surface to overlap the stack number uniform
section.
44. The battery of claim 43, wherein the number of overlapping
layers in the stack number uniform section is 10 or more.
45. The battery of claim 44, wherein the tab coupling portion is
welded to the bent surface, and a welding region of the tab
coupling portion overlaps the stack number uniform section by at
least 50% in the radial direction of the electrode assembly.
46. The battery of claim 1, wherein the first current collector
comprises a circular hole at a central portion of the first current
collector.
47. The battery of claim 46, wherein a diameter of the circular
hole of the first current collector is equal to or greater than a
diameter of a winding central hole formed in a core of the
electrode assembly.
48. The battery of claim 5, further comprising a sealing gasket
provided between the battery housing and the cap.
49. The battery of claim 48, wherein the contact portion is located
between the sealing gasket and the beading portion.
50. The battery of claim 48, wherein a thickness of the sealing
gasket varies in a circumferential direction.
51. The battery of claim 48, wherein a thickness of the sealing
gasket is alternately increased and decreased in a circumferential
direction.
52. The battery of claim 50, wherein the sealing gasket has a same
compressibility in a region where the sealing gasket contacts the
contact portion and in a region where the sealing gasket does not
contact the contact portion.
53. The battery of claim 50, wherein a compressibility of the
sealing gasket in a region where the sealing gasket does not
contact the contact portion is less than a compressibility of the
sealing gasket in a region where the sealing gasket contacts the
contact portion.
54. The battery of claim 48, wherein a thickness of the sealing
gasket in a region where the sealing gasket does not contact the
contact portion is greater than a thickness of the sealing gasket
in a region where the sealing gasket contacts the contact
portion.
55. The battery of claim 1, wherein the first current collector has
a leg structure where the tab coupling portion and the housing
coupling portion are connected to each other and extending in a
radial direction.
56. The battery of claim 55, comprising a plurality of the leg
structures.
57. The battery of claim 55, wherein the leg structures are
arranged in a radial shape, a cross shape, or a combined shape
thereof based on a central portion of the first current
collector.
58. The battery of claim 56, wherein a plurality of the housing
coupling portions are provided, and wherein the plurality of
housing coupling portions are connected to one another and
integrally formed.
59. The battery of claim 5, wherein the connecting portion
comprises at least one bending portion in which an extension
direction is changed at least once.
60. The battery of claim 59, wherein a protruding outermost point
of the bending portion is spaced apart by a certain interval from
an innermost point of the beading portion.
61. The battery of claim 59, wherein an angle between the contact
portion and the connecting portion is an acute angle due to the
bending portion.
62. The battery of claim 59, wherein the connecting portion is
elastically biased upward by the bending portion.
63. The battery of claim 5, wherein a circumferential length of the
contact portion is the same as a circumferential length of the tab
coupling portion.
64. The battery of claim 5, wherein a circumferential length of the
contact portion is the same as a circumferential length of the
connecting portion.
65. The battery of claim 5, wherein a circumferential length of the
contact portion is greater than a circumferential length of the tab
coupling portion.
66. The battery of claim 5, wherein a circumferential length of the
contact portion is greater than a circumferential length of the
connecting portion.
67. The battery of claim 5, wherein the contact portion has an arc
shape extending in a circumferential direction along the beading
portion of the battery housing.
68. The battery of claim 5, wherein the contact portion has an arc
shape extending in opposite directions to each other along a
circumferential direction from an intersection point of the
connecting portion and the contact portion.
69. The battery of claim 67, wherein a sum of lengths of the
contact portions extending in the circumferential direction
corresponds to a length of an inner circumference of the battery
housing.
70. The battery of claim 67, wherein the connecting portion has an
arc shape extending in the circumferential direction along the
contact portion.
71. The battery of claim 2, wherein a boundary region between the
tab coupling portion and the housing coupling portion is bent such
that an end portion of the housing coupling portion faces towards
the beading portion.
72. The battery of claim 5, wherein a connected portion between the
contact portion and the connecting portion is bent.
73. The battery of claim 5, wherein a connected portion between the
contact portion and the connecting portion has a complementary
shape corresponding to an inner surface of the beading portion.
74. The battery of claim 5, wherein a connected portion between the
contact portion and the connecting portion is coupled to the
beading portion while having a shape matching an inner surface of
the beading portion.
75. The battery of claim 1, wherein a boundary region between the
tab coupling portion and the housing coupling portion is located
farther inward than an innermost point of the beading portion
formed on the battery housing.
76. The battery of claim 2, wherein, when viewed along a
longitudinal axis of the battery housing, the tab coupling portion
does not overlap the beading portion.
77. The battery of claim 1, wherein the second electrode has a pair
of third sides and a pair of fourth sides extending between the
pair of third sides, a third portion including an active material
layer extending between the pair of third sides, and a fourth
portion extending between the pair of third sides, and the fourth
portion is exposed beyond the separator, at least a part of the
fourth portion includes an electrode tab, and wherein the battery
further comprises a terminal provided opposite to the first opening
at the first end of the battery housing and electrically connected
to the fourth portion.
78. The battery of claim 77, further comprising a second current
collector between the fourth portion of the second electrode and
the terminal, the second current collector comprising a tab
coupling portion coupled to the fourth portion of the second
electrode and a terminal coupling portion coupled to the
terminal.
79. The battery of claim 78, wherein the terminal coupling portion
covers a winding central hole of the electrode assembly.
80. The battery of claim 79, wherein a longest radius from a center
of the terminal coupling portion of the second current collector to
an end of the tab coupling portion of the second current collector
is greater than a longest radius from a central portion of the
first current collector to an end of the tab coupling portion of
the first current collector.
81. The battery of claim 78, wherein the tab coupling portion of
the second current collector is coupled to a bent end portion of
the fourth portion of the second electrode.
82. The battery of claim 81, further comprising a welding region
coupling the tab coupling portion of the second current collector
to the bent end portion of the fourth portion of the second
electrode, wherein a distance from a center of the terminal
coupling portion of the second current collector to the welding
region of the second current collector is the same as, or deviates
by 5% or less from, a distance from a central portion of the first
current collector to a welding region on the tab coupling portion
of the first current collector.
83. The battery of claim 82, wherein the welding region of the
second current collector has a length greater than a length of the
welding region on the tab coupling portion of the first current
collector.
84. The battery of claim 1, wherein one or more holes for injecting
an electrolytic solution are formed in the tab coupling
portion.
85. The battery of claim 1, wherein a form factor ratio obtained by
dividing a diameter of the battery by a height is greater than
0.4.
86. The battery of claim 1, wherein resistance measured between a
positive electrode and a negative electrode is equal to or less
than 4 mohm.
87. A battery pack comprising the battery according to claim 1.
88. The battery pack of claim 87, wherein a plurality of batteries
are arranged in a certain number of columns, and wherein a terminal
and an outer surface of the second end of a battery housing of each
of the plurality of batteries are positioned vertically upward.
89. The battery pack of claim 88, further comprising a plurality of
bus bars connecting the plurality of batteries in series and in
parallel, wherein each of the plurality of bus bars is located on
adjacent batteries among the plurality of batteries, wherein each
of the plurality of bus bars comprises: a body portion extending
between the adjacent batteries; a plurality of first bus bar
terminals extending in a first side direction of the body portion
and electrically coupled to terminals of the adjacent batteries
located in the first side direction; and a plurality of second bus
bar terminals extending in a second side direction of the body
portion opposite the first direction and electrically connected to
an outer surface of the second end of the battery housing of each
of the adjacent batteries located in the second side direction.
90. A vehicle comprising the battery pack according to claim
87.
91. A current collector comprising: at least one tab coupling
portion to be coupled to a portion of an electrode of an electrode
assembly; and at least one housing coupling portion extending from
the tab coupling portion and to be electrically coupled to a
beading portion of a battery housing.
92. A battery comprising: an electrode assembly including a first
electrode, a second electrode, and a separator between the first
electrode and the second electrode, wherein the first electrode,
the second electrode, and the separator are wound about an axis,
wherein the first electrode has a pair of first sides and a pair of
second sides extending between the pair of first sides, a first
portion including an active material layer extending between the
pair of first sides, and a second portion extending between the
pair of first sides and exposed beyond the separator, wherein at
least a part of the second portion includes an electrode tab; a
battery housing in which the electrode assembly is accommodated
through a first opening formed at a first end; a first current
collector electrically connected to the second portion of the first
electrode and an inner surface of the battery housing; and a
sealing gasket located between the first opening of the battery
housing and the first current collector, wherein a portion of the
first current collector contacting the inner surface of the battery
housing is located between the inner surface of the battery housing
and the sealing gasket.
93. The battery of claim 92, wherein the battery housing comprises
a beading portion formed on an end portion adjacent to the first
opening at the first end and press-fitted inward.
94. The battery of claim 38, wherein an extension direction of a
welding pattern formed between the second portion of the first
electrode and the tab coupling portion and an extension direction
of a welding pattern formed between the beading portion and the
contact portion are perpendicular to each other.
95. The battery of claim 3, wherein an innermost point of the
beading portion is located farther inward in a radial direction
than a distal point of the crimping portion.
96. The battery of claim 48, wherein the sealing gasket surrounds
the cap, and wherein a radial length of a portion of the sealing
gasket covering a bottom surface of the cap is less than a radial
length of a portion of the sealing gasket covering a top surface of
the cap.
97. The battery of claim 41, wherein a total radial length of the
tab coupling portion T satisfies the following formula:
JR-2*F.ltoreq.T<JR wherein JR is an outer diameter of the
electrode assembly, and F is a height of an outermost segment of
the electrode assembly.
98. The battery of claim 30, wherein a minimum value of a distance
from the innermost point of the beading portion to the central
point of the outermost welding bead in the radial direction W1 and
a distance from the innermost point of the beading portion to the
central point of an outermost welding bead in the radial direction
W satisfy the following formula: W1=R1+0.5*W.sub.bead,min, and
W=OV-0.5*W.sub.bead,min wherein OV is the overlap length, and R1 is
a radius of curvature of the beading portion.
99. The battery of claim 30, wherein the beading portion has a flat
section parallel to a bottom surface of the battery housing in at
least a region, and when the overlap length is OV and a radius of
curvature of the beading portion is R1, a length of the flat
section of the beading portion contacting the first current
collector is OV-R1.
100. The battery of claim 99, wherein a width in the radial
direction of a welding pattern formed between the beading portion
and the contact portion is equal to or greater than W.sub.bead,min
and equal to or less than OV-R1.
101. The battery of claim 100, wherein a ratio of the width in the
radial direction of the welding pattern to a length of the flat
section ranges from 10% to 40%.
102. The battery of claim 1, wherein a ratio of an area where the
first current collector does not contact a top surface of the
electrode assembly to an area of a circle having an outer diameter
of the electrode assembly is equal to or greater than 30% and less
than 100%.
103. The battery of claim 1, wherein a ratio of an area where the
first current collector does not contact a top surface of the
electrode assembly to an area of a circle having an outer diameter
of the electrode assembly is equal to or greater than 60% and less
than 100%.
104. The battery of claim 46, wherein a diameter of the circular
hole of the first current collector is less than a diameter of a
winding central hole formed in a core of the electrode
assembly.
105. The battery of claim 104, wherein a diameter of the circular
hole of the first current collector is equal to or greater than
0.5*R3 and less than R3, wherein R3 is a diameter of the winding
central hole.
106. The battery of claim 104, wherein a diameter of the circular
hole of the first current collector is equal to or greater than
0.7*R3 and less than R3, wherein R3 is a diameter of the winding
central hole.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This non-provisional application claims the benefit under 35
U.S.C. .sctn. 119(a) to Patent Application No. 10-2021-0022881,
filed in the Republic of Korea on Feb. 19, 2021, Patent Application
No. 10-2021-0022891, filed in the Republic of Korea on Feb. 19,
2021, Patent Application No. 10-2021-0022894, filed in the Republic
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filed in the Republic of Korea on Feb. 19, 2021, Patent Application
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of Korea on Dec. 31, 2021, and Patent Application No.
10-2022-0001802, filed in the Republic of Korea on Jan. 5, 2022,
all of which are hereby expressly incorporated by reference in
their entireties into the present application.
[0002] Also, Patent Application No. 10-2021-0007278, filed in the
Republic of Korea on Jan. 19, 2021, is hereby expressly
incorporated by reference in its entirety into the present
application.
TECHNICAL FIELD
[0003] The present disclosure relates to a battery and a current
collector applied thereto, and a battery pack and a vehicle
including the battery.
BACKGROUND ART
[0004] A battery according to the related art generally has a
structure in which a tab for connecting a jelly-roll to an external
terminal is welded and connected to a foil of the jelly-roll. The
battery having the above structure has a limited current path and
has very high resistance of the jelly-roll itself.
[0005] Accordingly, a method of reducing the resistance by
increasing the number of tabs for connecting the jelly-roll to the
external terminal has been attempted, but there is a limitation in
reducing the resistance to a desired level and sufficiently
securing current paths only by increasing the number of tabs.
[0006] Therefore, it is demanded to develop a new jelly-roll
structure for reducing self-resistance of the jelly-roll and to
develop a current collector structure suitable for the new
jelly-roll structure. In particular, the necessity for application
of the jelly-roll and the current collector having a new structure
is much required for a device, e.g., an electric vehicle, which
needs a battery pack having high output/high capacity.
[0007] Also, there is a need to develop a battery having a
structure in which a coupling force between a current collector and
a battery housing is improved and maintained at an improved level,
and a current collector applied to the battery.
[0008] In addition, there is a need to develop a battery having
improved energy density, by minimizing a dead space in a battery
housing when a current collector and the battery housing are
coupled to each other.
[0009] As a battery has recently been applied to an electric
vehicle, a form factor of the battery has increased. That is, a
diameter and a height of a battery have increased when compared to
a conventional battery having a form factor of 1865, 2170, or the
like. An increase in a form factor leads to increased energy
density, enhanced safety against thermal runaway, and improved
cooling efficiency.
[0010] The energy density of a battery may be further increased
when an unnecessary space in a battery housing is minimized along
with an increase in a form factor. Accordingly, it is necessary to
design an entire structure of a battery as a low-resistive
structure so that a current collector minimizes the amount of heat
generated during rapid charging while increasing the capacity of a
battery.
DISCLOSURE
Technical Problem
[0011] The present disclosure is designed to solve the problems of
the related art, and therefore the present disclosure is directed
to providing a current collector having a structure suitable for an
electrode assembly having a low-resistive structure, and a battery
including the current collector.
[0012] The present disclosure is also directed to providing a
current collector having a structure capable of improving a
coupling force of a coupling portion between the current collector
and a battery housing, and a battery including the current
collector.
[0013] The present disclosure is also directed to providing a
current collector having a structure capable of improving the
energy density of a battery, and a battery including the current
collector.
[0014] The present disclosure is also directed to providing a
current collector having a structure capable of improving
convenience in a welding process for electrical connection between
a battery housing and the current collector and improving
productivity when a battery is manufactured, and a battery
including the current collector.
[0015] However, the technical purpose to be solved by the present
disclosure are not limited to the above, and other objects not
mentioned herein will be clearly understood by one of ordinary
skill in the art from the following disclosure.
Technical Solution
[0016] A battery according to an embodiment of the present
disclosure includes: an electrode assembly including a first
electrode, a second electrode, and a separator between the first
electrode and second electrode, wherein the first electrode, the
second electrode, and the separator are wound about an axis,
wherein the first electrode has a pair of first sides and a pair of
second sides extending between the pair of first sides, a first
portion including an active material extending between the pair of
first sides, and a second portion extending between the pair of
first sides and exposed beyond the separator, wherein at least a
part of the second portion includes an electrode tab; a battery
housing having a first end with a first opening, a second end with
a second opening opposite the first end, and an inner surface, the
battery housing accommodating the electrode assembly through the
first opening formed at the first end; a first current collector
comprising a tab coupling portion coupled to the second portion of
the first electrode and a housing coupling portion extending from
the tab coupling portion and electrically coupled to the inner
surface of the battery housing; and a cap covering the first
opening of the battery housing.
[0017] Preferably, the battery housing may include a beading
portion formed on an end portion adjacent to the first opening at
the first end and press-fitted inward.
[0018] Preferably, the battery housing may include a crimping
portion formed at a position between the first opening at the first
end and the beading portion, and extending and bent toward the
first opening.
[0019] In particular, the housing coupling portion may be
press-fixed by the crimping portion.
[0020] In an aspect of the present disclosure, the housing coupling
portion may include: a contact portion coupled to the beading
portion of the battery housing; and a connecting portion to connect
the tab coupling portion to the contact portion.
[0021] Preferably, the connecting portion may be upwardly convex
based on an imaginary straight line that connects an end portion of
the contact portion to an end portion of the tab coupling
portion.
[0022] In another aspect of the present disclosure, the connecting
portion may be lifted upward above the beading portion.
[0023] Preferably, the connecting portion may include at least one
bent part.
[0024] Preferably, the bent part may be located over an imaginary
plane that passes through a center of the imaginary straight line
that connects the end portion of the contact portion to the end
portion of the tab coupling portion, and is parallel to a bottom
surface of the battery housing.
[0025] In another aspect of the present disclosure, the at least
one bent part may be bent at an obtuse angle so as not to overlap
itself when viewed along a longitudinal axis of the battery
housing.
[0026] In another aspect of the present disclosure, a boundary
point between the contact portion and the connecting portion may be
bent at an obtuse angle.
[0027] In another aspect of the present disclosure, an inclination
of the connecting portion may be reduced stepwise or gradually
toward the beading portion.
[0028] In another aspect of the present disclosure, an angle
between the tab coupling portion and the connecting portion may
range from 0.degree. to 90.degree..
[0029] In another aspect of the present disclosure, the connecting
portion may support the cap.
[0030] In another aspect of the present disclosure, the tab
coupling portion and the contact portion may be located at a same
height.
[0031] In another aspect of the present disclosure, the contact
portion may include a flat surface coupled to a top surface of the
beading portion facing the opening portion.
[0032] In another aspect of the present disclosure, the beading
portion may include: a beading portion top surface located over an
innermost point that is press-fitted inward; and a beading portion
bottom surface located under the innermost point that is
press-fitted inward.
[0033] Preferably, the tab coupling portion may be located at a
lower position than the beading portion bottom surface.
[0034] In another aspect of the present disclosure, at least one of
the beading portion top surface and the beading portion bottom
surface may be inclined at a certain angle with respect to a bottom
surface of the battery housing.
[0035] In this case, the contact portion may be mounted on an
inclined top surface of the beading portion.
[0036] In another aspect of the present disclosure, at least one of
the beading portion top surface and the beading portion bottom
surface may be parallel to a bottom surface of the battery housing
in at least a region.
[0037] In another aspect of the present disclosure, the beading
portion top surface and the beading portion bottom surface may be
asymmetric with respect to an imaginary reference plane that passes
through the innermost point of the beading portion to be parallel
to a bottom surface of the battery housing.
[0038] Preferably, the contact portion may be mounted on a flat top
surface of the beading portion.
[0039] In another aspect of the present disclosure, a press-fitting
depth of the beading portion PD satisfies the following
formula:
PD.gtoreq.R.sub.1,min+R.sub.2,min+W.sub.bead,min
[0040] wherein R.sub.1,min is a minimum value of a radius of
curvature of the beading portion, W.sub.bead,min is a minimum value
of a welding bead width, and R.sub.2,min is a minimum value of a
radius of curvature at a boundary region between the beading
portion and the inner surface of the battery housing.
[0041] Preferably, a press-fitting depth of the beading portion may
range from 0.2 mm to 10 mm.
[0042] In another aspect of the present disclosure, a press-fitting
depth of the beading portion PD and a maximum value of the
press-fitting depth PD.sub.max satisfies the following formula:
(R.sub.1,min+W.sub.bead,min)/PD.sub.max.ltoreq.OV/PD.ltoreq.(PD.sub.max--
R.sub.2,min)/PD.sub.max
wherein OV is an overlap length that is a shortest distance from an
end portion of the contact portion to a vertical line that passes
through an innermost point of the beading portion, R.sub.1,min is a
minimum value of a radius of curvature of the beading portion,
W.sub.bead,min is a minimum value of a welding bead width, and
R.sub.2,min is a minimum value of a radius of curvature at a
boundary region between the beading portion and the inner surface
of the battery housing.
[0043] In another aspect of the present disclosure, the contact
portion may be welded to the beading portion.
[0044] Preferably, the contact portion may be welded to a flat top
surface of the beading portion.
[0045] More preferably, a welding region between the contact
portion and the beading portion may be narrower than the flat top
surface of the beading portion.
[0046] In another aspect of the present disclosure, a press-fitting
depth of the beading portion PD and a maximum value of the
press-fitting depth PD.sub.max satisfies the following formula:
(OV.sub.min-0.5*W.sub.bead,min)/PD.sub.max.ltoreq.W/PD.ltoreq.(OV.sub.ma-
x-0.5*W.sub.bead,min)/PD.sub.max
[0047] W is a distance from an innermost point of the beading
portion to a central point of an outermost welding bead in a radial
direction, OV is an overlap length that is a shortest distance from
an end portion of the contact portion to a vertical line that
passes through the innermost point of the beading portion,
OV.sub.min is a minimum value of the overlap length OV, OV.sub.max
is a maximum value of the overlap length OV, and W.sub.bead,min is
a minimum value of a welding bead width.
[0048] In another aspect of the present disclosure, at least one
welding bead may be formed between the beading portion and the
contact portion.
[0049] Preferably, the at least one welding bead may form a welding
pattern having a straight line shape extending in a circumferential
direction.
[0050] In another aspect of the present disclosure, at least one
welding bead may be formed between the beading portion and the
contact portion, wherein the at least one welding bead forms a
welding pattern having an arc shape extending in a circumferential
direction.
[0051] In another aspect of the present disclosure, a welding bead
formed between the beading portion and the contact portion may form
a welding pattern, wherein the welding pattern has a linear shape
in which spot welding is connected.
[0052] In another aspect of the present disclosure, a plurality of
welding beads are formed between the beading portion and the
contact portion.
[0053] In another aspect of the present disclosure, a width of a
welding bead formed between the beading portion and the contact
portion may be equal to or greater than 0.1 mm.
[0054] In another aspect of the present disclosure, the second
portion of the first electrode and the tab coupling portion may be
welded in a radial direction of the electrode assembly.
[0055] In another aspect of the present disclosure, the tab
coupling portion may be welded to the second portion of the first
electrode while being parallel to a bottom surface of the battery
housing.
[0056] In another aspect of the present disclosure, a plurality of
welding beads formed between the second portion of the first
electrode and the tab coupling portion may form a welding pattern
having a straight line shape extending in the radial direction of
the electrode assembly.
[0057] In another aspect of the present disclosure, a welding bead
formed between the second portion of the first electrode and the
tab coupling portion may form a welding pattern, wherein the
welding pattern has a linear shape in which spot welding is
connected.
[0058] In another aspect of the present disclosure, a width of a
welding bead formed between the second portion of the first
electrode and the tab coupling portion may be equal to or greater
than 0.1 mm.
[0059] In another aspect of the present disclosure, at least a part
of the second portion of the first electrode may include a
plurality of segments divided in a winding direction of the
electrode assembly.
[0060] Preferably, the plurality of segments may be bent in a
radial direction of the electrode assembly to form a bent
surface.
[0061] Preferably, the plurality of segments may overlap in
multiple layers in the radial direction of the electrode assembly
to form the bent surface.
[0062] More preferably, the bent surface may include a stack number
increasing section in which the number of overlapping layers of the
segments is sequentially increased to a maximum value from an outer
circumference to a core of the electrode assembly and a stack
number uniform section from a radius point at which the number of
overlapping layers is the maximum value to a radius point at which
an innermost segment exists.
[0063] Preferably, the tab coupling portion may be coupled to the
bent surface to overlap the stack number uniform section.
[0064] More preferably, the number of overlapping layers in the
stack number uniform section may be 10 or more.
[0065] More preferably, the tab coupling portion may be welded to
the bent surface, and a welding region of the tab coupling portion
may overlap the stack number uniform section by at least 50% in the
radial direction of the electrode assembly.
[0066] In another aspect of the present disclosure, the first
current collector may include a collector hole at a central portion
of the first current collector.
[0067] Preferably, a diameter of the collector hole of the first
current collector may be equal to or greater than a diameter of a
winding central hole formed in a core of the electrode
assembly.
[0068] In another aspect of the present disclosure, the battery may
include a sealing gasket provided between the battery housing and
the cap.
[0069] Preferably, the contact portion may be located between the
sealing gasket and the beading portion.
[0070] More preferably, a thickness of the sealing gasket may vary
in a circumferential direction.
[0071] Preferably, a thickness of the sealing gasket may be
alternately increased and decreased in a circumferential
direction.
[0072] In an aspect of the present disclosure, the sealing gasket
may have a same compressibility in a region where the sealing
gasket contacts the contact portion and in a region where the
sealing gasket does not contact the contact portion.
[0073] In another aspect of the present disclosure, a
compressibility of the sealing gasket in a region where the sealing
gasket does not contact the contact portion may be less than a
compressibility of the sealing gasket in a region where the sealing
gasket contacts the contact portion.
[0074] Preferably, a thickness of the sealing gasket in a region
where the sealing gasket does not contact the contact portion may
be greater than a thickness of the sealing gasket in a region where
the sealing gasket contacts the contact portion.
[0075] In another aspect of the present disclosure, the first
current collector may have a leg structure where the tab coupling
portion and the housing coupling portion are connected to each
other and extending in a radial direction.
[0076] Preferably, a plurality of leg structures may be
provided.
[0077] Preferably, the leg structures may be arranged in a radial
shape, a cross shape, or a combined shape thereof based on a
central portion of the first current collector.
[0078] In another aspect of the present disclosure, a plurality of
the housing coupling portions may be provided, and wherein the
plurality of housing coupling portions are connected to one another
and integrally formed.
[0079] In another aspect of the present disclosure, the connecting
portion may include at least one bending portion in which an
extension direction is changed at least once.
[0080] Preferably, a protruding outermost point of the bending
portion may be spaced apart by a certain interval from an innermost
point of the beading portion.
[0081] In another aspect of the present disclosure, an angle
between the contact portion and the connecting portion may be an
acute angle due to the bending portion.
[0082] In another aspect of the present disclosure, the connecting
portion may be elastically biased upward by the bending
portion.
[0083] In another aspect of the present disclosure, a
circumferential length of the contact portion may be the same as a
circumferential length of the tab coupling portion.
[0084] In another aspect of the present disclosure, a
circumferential length of the contact portion may be the same as a
circumferential length of the connecting portion.
[0085] In another aspect of the present disclosure, a
circumferential length of the contact portion may be greater than a
circumferential length of the tab coupling portion.
[0086] In another aspect of the present disclosure, a
circumferential length of the contact portion may be greater than a
circumferential length of the connecting portion.
[0087] In another aspect of the present disclosure, the contact
portion may have an arc shape extending in a circumferential
direction along the beading portion of the battery housing.
[0088] In another aspect of the present disclosure, the contact
portion may have an arc shape extending in opposite directions to
each other along a circumferential direction, from an intersection
point of the connecting portion and the contact portion.
[0089] In another aspect of the present disclosure, a sum of
lengths of the contact portions extending in the circumferential
direction may correspond to a length of an inner circumference of
the battery housing.
[0090] In another aspect of the present disclosure, the connecting
portion may have an arc shape extending in the circumferential
direction along the contact portion.
[0091] In another aspect of the present disclosure, a boundary
region between the tab coupling portion and the housing coupling
portion may be bent such that an end portion of the housing
coupling portion faces towards the beading portion.
[0092] In another aspect of the present disclosure, a connected
portion between the contact portion and the connecting portion may
be bent.
[0093] In another aspect of the present disclosure, a connected
portion between the contact portion and the connecting portion may
have a complementary shape corresponding to an inner surface of the
beading portion.
[0094] In another aspect of the present disclosure, a connected
portion between the contact portion and the connecting portion may
be coupled to the beading portion while having a shape matching an
inner surface of the beading portion.
[0095] In another aspect of the present disclosure, a boundary
region between the tab coupling portion and the housing coupling
portion may be located farther inward than an innermost point of
the beading portion formed on the battery housing.
[0096] Preferably, when viewed along a longitudinal axis of the
battery housing, the tab coupling portion may not overlap the
beading portion.
[0097] In another aspect of the present disclosure, the second
electrode may include has a pair of third sides and a pair of
fourth sides extending between the pair of third sides, a third
portion including an active material layer extending between the
pair of third sides, and a fourth portion extending between the
pair of third sides, and the fourth portion is exposed beyond the
separator, at least a part of the fourth portion includes an
electrode tab, and wherein the battery may further include a
terminal provided opposite to the first opening at the first end of
the battery housing and electrically connected to the fourth
portion.
[0098] Preferably, the battery may further include a second current
collector between the fourth portion of the second electrode and
the terminal, the second current collector including a tab coupling
portion coupled to the fourth portion of the second electrode and a
terminal coupling portion coupled to the terminal.
[0099] Preferably, the terminal coupling portion may cover a
winding central hole of the electrode assembly.
[0100] Preferably, a longest radius from a center of the terminal
coupling portion of the second current collector to an end of the
tab coupling portion of the second current collector may be greater
than a longest radius from a central portion of the first current
collector to an end of the tab coupling portion of the first
current collector.
[0101] In another aspect of the present disclosure, the tab
coupling portion of the second current collector may be coupled to
a bent end portion of the fourth portion of the second
electrode.
[0102] Preferably, the battery includes a welding region coupling
the tab coupling portion of the second current collector to the
bent end portion of the fourth portion of the second electrode,
wherein a distance from a center of the terminal coupling portion
of the second current collector to the welding region of the second
current collector is same as, or deviates by 5% or less, from a
distance from a central portion of the first current collector to a
welding region on the tab coupling portion of the current
collector.
[0103] Preferably, the welding region of the second current
collector may have a length greater than a length of the welding
region on the tab coupling portion of the first current
collector.
[0104] In another aspect of the present disclosure, one or more
holes for injecting an electrolytic solution may be formed in the
tab coupling portion.
[0105] In another aspect of the present disclosure, a form factor
ratio obtained by dividing a diameter of the battery by a height
may be greater than 0.4.
[0106] In another aspect of the present disclosure, resistance
measured between a positive electrode and a negative electrode may
be equal to or less than 4 mohm.
[0107] A battery pack according to an embodiment of the present
disclosure includes a plurality of batteries according to an
embodiment of the present disclosure as described above.
[0108] Preferably, a plurality of batteries may be arranged in a
certain number of columns, wherein a terminal and an outer surface
of the second end of a battery housing of each of the plurality of
batteries are positioned upward.
[0109] In an aspect of the present disclosure, the battery pack may
further include a plurality of bus bars connecting the plurality of
batteries in series and in parallel, wherein each of the plurality
of bus bars is located on adjacent batteries among the plurality of
batteries, wherein each of the plurality of bus bars includes: a
body portion extending between the adjacent batteries; a plurality
of first bus bar terminals extending in a first side direction of
the body portion and electrically coupled to terminals of the
adjacent batteries located in the first side direction; and a
plurality of second bus bar terminals extending in a second side
direction of the body portion opposite the first direction and
electrically connected to an outer surface of the second end of the
battery housing of each of the adjacent batteries located in the
second side direction.
[0110] A vehicle according to an embodiment of the present
disclosure includes the battery pack according to an embodiment of
the present disclosure.
[0111] A current collector according to an embodiment of the
present disclosure includes: at least one tab coupling portion to
be coupled to a portion of an electrode of an electrode assembly;
and at least one housing coupling portion extending from the tab
coupling portion and electrically coupled to a beading portion of a
battery housing.
[0112] A battery according to another embodiment of the present
disclosure includes: an electrode assembly including a first
electrode, a second electrode, and a separator between the first
electrode and the second electrode, wherein the first electrode,
the second electrode, and the separator are wound about an axis,
wherein the first electrode has a pair of first sides and a pair of
second sides extending between the pair of first sides, a first
portion including an active material layer extending between the
pair of first sides, and a second portion extending between the
pair of first sides and exposed beyond the separator, wherein at
least a part of the second portion includes an electrode tab; a
battery housing in which the electrode assembly is accommodated
through a first opening formed at a first end; a first current
collector electrically connected to the second portion of the first
electrode and an inner surface of the battery housing; and a
sealing gasket located between the first opening of the battery
housing and the first current collector, wherein a portion of the
first current collector contacting the inner surface of the battery
housing is located between the inner surface of the battery housing
and the sealing gasket.
[0113] Preferably, the battery housing may include a beading
portion formed on an end portion adjacent to the first opening at
the first end and press-fitted inward.
[0114] In another aspect of the present disclosure, an extension
direction of a welding pattern formed between the second portion of
the first electrode and the tab coupling portion and an extension
direction of a welding pattern formed between the beading portion
and the contact portion may be perpendicular to each other.
[0115] In another aspect of the present disclosure, an innermost
point of the beading portion may be located farther inward in a
radial direction than a distal point of the crimping portion.
[0116] In another aspect of the present disclosure, the sealing
gasket may surround the cap, wherein a radial length of a portion
of the sealing gasket covering a bottom surface of the cap is less
than a radial length of a portion of the sealing gasket covering a
top surface of the cap.
[0117] In another aspect of the present disclosure, a total radial
length of the tab coupling portion T satisfies the following
formula:
JR-2*F.ltoreq.T<JR
[0118] wherein JR is an outer diameter of the electrode assembly,
and F is a height of an outermost segment of the electrode
assembly.
[0119] In another aspect of the present disclosure, a minimum value
of a distance from the innermost point of the beading portion to
the central point of the outermost welding bead in the radial
direction W1 and a distance from the innermost point of the beading
portion to the central point of an outermost welding bead in the
radial direction W satisfy the following formula:
W1=R1+0.5*W.sub.bead,min, and
W=OV-0.5*W.sub.bead,min
[0120] wherein OV is the overlap length, and R1 is a radius of
curvature of the beading portion.
[0121] In another aspect of the present disclosure, the beading
portion may have a flat section parallel to a bottom surface of the
battery housing in at least a region, and when the overlap length
is OV and a radius of curvature of the beading portion is R1, a
length of the flat section of the beading portion contacting the
first current collector may be OV-R1.
[0122] Preferably, a width in the radial direction of a welding
pattern formed between the beading portion and the contact portion
may be equal to or greater than W.sub.bead,min and equal to or less
than OV-R1.
[0123] In another aspect of the present disclosure, a ratio of the
width in the radial direction of the welding pattern to a length of
the flat section may range from 10% to 40%.
[0124] In another aspect of the present disclosure, a ratio of an
area where the first current collector does not contact a top
surface of the electrode assembly to an area of a circle having an
outer diameter of the electrode assembly may be equal to or greater
than 30% and less than 100%.
[0125] More preferably, a ratio of an area where the first current
collector does not contact a top surface of the electrode assembly
to an area of a circle having an outer diameter of the electrode
assembly may be equal to or greater than 60% and less than
100%.
[0126] In another aspect of the present disclosure, a diameter of
the circular hole of the first current collector may be less than a
diameter of a winding central hole formed in a core of the
electrode assembly.
[0127] Preferably, a diameter of the circular hole of the first
current collector is equal to or greater than 0.5*R3 and less than
R3, wherein R3 is a diameter of the winding central hole.
[0128] More preferably, a diameter of the circular hole of the
first current collector is equal to or greater than 0.7*R3 and less
than R3, wherein R3 is a diameter of the winding central hole.
Advantageous Effects
[0129] According to the present disclosure, resistance may be
greatly reduced in electrical connection between an electrode
assembly and a battery housing.
[0130] Also, according to the present disclosure, a coupling force
of a coupling portion between a current collector and a battery
housing may be improved.
[0131] In addition, according to the present disclosure, the energy
density of a battery may be improved.
[0132] Also, according to the present disclosure, when a battery is
manufactured, convenience in a welding process for electrical
connection between a battery housing and a current collector may be
improved, and thus, productivity may be improved.
[0133] However, effects obtainable from the present disclosure may
be non-limited by the above-mentioned effect. Other unmentioned
effects may be clearly understood from the following description by
one of ordinary skill in the art to which the present disclosure
pertains.
DESCRIPTION OF DRAWINGS
[0134] The accompanying drawings illustrate embodiments of the
present disclosure and together with the foregoing disclosure,
serve to provide further understanding of the technical features of
the present disclosure, and thus, the present disclosure is not
construed as being limited to the drawing.
[0135] FIG. 1a is a longitudinal sectional view illustrating a part
of a battery, according to an embodiment of the present
disclosure.
[0136] FIG. 1b is a longitudinal sectional view illustrating a part
of a battery, according to another embodiment of the present
disclosure.
[0137] FIG. 1c is an enlarged view illustrating an upper portion of
an electrode assembly of FIG. 1b.
[0138] FIG. 1d is an enlarged view illustrating an upper portion of
a first uncoated portion of FIG. 1c.
[0139] FIG. 2 is a longitudinal sectional view illustrating a part
of a battery, according to another embodiment of the present
disclosure.
[0140] FIG. 3 is a longitudinal sectional view illustrating a part
of a battery, according to another embodiment of the present
disclosure.
[0141] FIG. 4a is a view for describing a current collector
included in the battery of FIG. 3.
[0142] FIG. 4b is a view for describing an embodiment where a
bending portion is omitted in the current collector of FIG. 4a.
[0143] FIG. 5 is a view for describing a current collector
according to another embodiment of the present disclosure.
[0144] FIG. 6 is a view for describing a current collector,
according to another embodiment of the present disclosure.
[0145] FIG. 7 is a view for describing a relationship between a
current collector hole and a winding hole.
[0146] FIG. 8a is a view for describing a welding region between a
current collector and a first uncoated portion and a welding region
between the current collector and a beading portion of FIG. 4a.
[0147] FIG. 8b is a view for describing a welding region between a
current collector and a first uncoated portion and a welding region
between the current collector and a beading portion of FIG. 4b.
[0148] FIG. 9 is a view for describing a welding region between a
current collector and a first uncoated portion and a welding region
between the current collector and a beading portion of FIG. 5.
[0149] FIG. 10 is a view for describing a welding region between a
current collector and a first uncoated portion and a welding region
between the current collector and a beading portion of FIG. 6.
[0150] FIG. 11 is a view for describing a position, a length, and a
width of a welding bead formed in a welding region between a
contact portion and a beading portion.
[0151] FIG. 12 is a view for describing a relationship between a
diameter of an inner surface of a battery housing and a total
diameter of a current collector.
[0152] FIG. 13a is a view for describing a welding process of a
current collector.
[0153] FIG. 13b is a view for describing a beading process of a
battery housing.
[0154] FIG. 13c is a view for describing a crimping process of a
battery housing.
[0155] FIG. 13d is a view for describing a sizing process of a
battery housing.
[0156] FIG. 13e is a view for describing a change in a current
collector after a sizing process according to a shape of the
current collector before a sizing process.
[0157] FIG. 13f is a view for describing a shape of a current
collector for maintaining a welding region even after a sizing
process.
[0158] FIG. 13g is a view for describing a shape of a current
collector for maintaining a welding region even after a sizing
process.
[0159] FIG. 14 is a plan view illustrating an electrode plate
structure according to an embodiment of the present disclosure.
[0160] FIG. 15 is a cross-sectional view illustrating an electrode
assembly in which an uncoated portion segmentation structure of an
electrode plate is applied to a first electrode plate and a second
electrode plate, taken along a longitudinal direction Y, according
to an embodiment of the present disclosure.
[0161] FIG. 16a is a cross-sectional view illustrating an electrode
assembly in which an uncoated portion is bent, taken along the
longitudinal direction Y, according to an embodiment of the present
disclosure.
[0162] FIG. 16b is a perspective view illustrating an electrode
assembly in which an uncoated portion is bent according to an
embodiment of the present disclosure.
[0163] FIG. 17 is a top plan view illustrating a state where a
plurality of batteries are connected in series and in parallel by
using a bus bar according to an embodiment of the present
disclosure.
[0164] FIG. 18a is a view for describing a second current collector
according to an embodiment of the present disclosure.
[0165] FIG. 18b is a view for describing a second current collector
according to another embodiment of the present disclosure.
[0166] FIG. 19 is a view for describing a battery pack including a
battery according to an embodiment of the present disclosure.
[0167] FIG. 20 is a view for describing a vehicle including the
battery pack of FIG. 19.
BEST MODE
[0168] Hereinafter, embodiments of the present disclosure will be
described in detail with reference to the accompanying drawings.
Prior to the description, it should be understood that the terms
used in the specification and the appended claims should not be
construed as limited to general and dictionary meanings, but
interpreted based on the meanings and concepts corresponding to
technical aspects of the present disclosure on the basis of the
principle that the inventor is allowed to define terms
appropriately for the best explanation. Therefore, the description
provided herein are just examples for the purpose of illustrations
only, not intended to limit the scope of the disclosure, so it
should be understood that other equivalents and modifications could
be made thereto without departing from the scope of the
disclosure.
[0169] In addition, in order to help the understanding of the
present disclosure, the accompanying drawings are not drawn to
scale, but dimensions of some components may be exaggerated. Also,
the same reference signs may be assigned to the same components in
different embodiments.
[0170] When it is explained that two objects are identical, this
means that these objects are `substantially identical`.
Accordingly, the substantially identical objects may include
deviations considered low in the art, for example, deviations
within 5%. Also, when it is explained that certain parameters are
uniform in a certain region, this may mean that the parameters are
uniform in terms of an average.
[0171] Referring to FIG. 1a, a battery 1 according to an embodiment
of the present disclosure includes an electrode assembly 10, a
battery housing 20, a current collector (first current collector)
30, and a cap 40. The battery 1 may further include a terminal 50
and/or a sealing gasket G1 and/or an insulating gasket G2 and/or a
current collector (second current collector) P and/or an insulator
S. The terminal 50 may be provided opposite to an opening portion,
and may be electrically connected to a second uncoated portion
12.
[0172] The electrode assembly 10 includes a first uncoated portion
11 and the second uncoated portion 12. In more detail, the
electrode assembly may be manufactured by winding a stack formed by
sequentially stacking a first electrode, a separator, a second
electrode, and a separator at least once. That is, the electrode
assembly 10 applied to the present disclosure may be a rolled
electrode assembly. In this case, an additional separator may be
provided on an outer circumferential surface of the electrode
assembly 10 for insulating from the battery housing 20. The
electrode assembly 10 may have a rolled structure well known in the
related art without limitation.
[0173] The electrode assembly 10 may be a rolled electrode assembly
having a structure in which a first electrode current collector and
a second electrode current collector each having a sheet shape and
a separator located between the first and second electrode current
collectors are wound in one direction. The first electrode may
include the first uncoated portion 11 that is not coated with an
active material layer and is exposed to the outside of the
separator at a long side end thereof. The second electrode may
include the second uncoated portion 12 that is not coated with an
active material layer and is exposed to the outside of the
separator at a long side end thereof. At least a part of the first
uncoated portion 11 may be used as an electrode tab by itself. At
least a part of the second uncoated portion 12 itself may be used
as an electrode tab by itself.
[0174] In detail, the first electrode includes a first electrode
current collector and a first electrode active material coated on
one surface or both surfaces of the first electrode current
collector. An uncoated portion on which the first electrode active
material is not coated exists at one end in a width direction of
the first electrode current collector (direction parallel to a
height direction of the battery 1 of FIG. 1a). The uncoated portion
functions as a first electrode tab. The first uncoated portion 11
is provided in an upper portion of the electrode assembly 10
accommodated in the battery housing 20 in a height direction
(direction parallel to a height direction of the battery 1 of FIG.
1a). The first uncoated portion 11 may be, for example, a negative
electrode tab.
[0175] The second electrode includes a second electrode current
collector and a second electrode active material coated on one
surface or both surfaces of the electrode current collector. An
uncoated portion on which the second electrode active material is
not coated exists at the other end in a width direction of the
second electrode current collector (direction parallel to the
height direction of the battery 1 of FIG. 1a). The uncoated portion
functions as a second electrode tab. The second uncoated portion 12
is provided on a lower portion in a height direction of the
electrode assembly 10 accommodated in the battery housing 20. The
second uncoated portion 12 may be, for example, a positive
electrode tab.
[0176] In the present disclosure, a positive electrode active
material coated on a positive electrode plate and a negative
electrode active material coated on a negative electrode plate may
be any type of active material, provided that the active material
is well known in the art.
[0177] In an example, the positive active electrode active material
may include an alkali metal compound expressed by a general
chemical formula A[A.sub.xM.sub.y]O.sub.2+z (A includes at least
one of Li, Na, and K; M includes at least one element selected from
Ni, Co, Mn, Ca, Mg, Al, Ti, Si, Fe, Mo, V, Zr, Zn, Cu, Al, Mo, Sc,
Zr, Ru, and Cr; x.gtoreq.0, 1.ltoreq.x+y.ltoreq.2,
-0.1.ltoreq.z.ltoreq.2; and stoichiometric coefficients x, y, and z
are selected so that the compound remains electrically
neutral).
[0178] In another embodiment, the positive electrode active
material may be an alkali metal compound
xLiM.sup.1O.sub.2(1x)Li.sub.2M.sup.2O.sub.3 (M.sup.1 includes at
least one element having an average oxide state of 3; M.sup.2
includes at least one element having an average oxidation state of
4; and 0.ltoreq.x.ltoreq.1) disclosed in U.S. Pat. Nos. 6,677,082,
6,680,143, etc.
[0179] In another example, the positive electrode active material
may be lithium metal phosphate expressed by a general chemical
formula
Li.sub.aM.sup.1.sub.xFe.sub.1xM.sup.2.sub.yP.sub.1yM.sup.3.sub.zO.sub.4z
(M.sup.1 includes at least one element selected from Ti, Si, Mn,
Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, and Al; M.sup.2 includes at
least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni,
Nd, Al, Mg, Al, As, Sb, Si, Ge, V, and S; M.sup.3 includes an
element of a halogen group selectively containing F;
0<a.ltoreq.2, 0.ltoreq.x.ltoreq.1, 0.ltoreq.y.ltoreq.1,
0.ltoreq.z<1; and stoichiometric coefficients a, x, y, and z are
selected so that the compound remains electrically neutral), or
Li.sub.3M.sub.2(PO.sub.4).sub.3 [M includes at least one element
selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Al, Mg, and
Al].
[0180] Preferably, the positive electrode active material may
include primary particles and/or secondary particles in which the
primary particles are aggregated.
[0181] In an example, the negative electrode active material may
use a carbon material, lithium metal or lithium metal compounds,
silicon or silicon compounds, tin or tin compounds, etc. Metal
oxide such as TiO.sub.2 or SnO.sub.2 having a potential of less
than 2 V may be also used as the negative electrode active
material. As the carbon material, low crystalline carbon and high
crystalline carbon may be used.
[0182] The separator may include a porous polymer film, for
example, made of a polyolefin-based polymer such as an ethylene
homopolymer, a propylene homopolymer, an ethylene/butene copolymer,
an ethylene/hexene copolymer, or an ethylene/methacrylate
copolymer, in a single or stack structure thereof. In another
example, the separator may be a common porous non-woven fabric, for
example, a non-woven fabric made of glass fiber having a high melt
point or polyethylene terephthalate fiber.
[0183] At least one surface of the separator may include a coating
layer of inorganic particles. Otherwise, the separator itself may
be made of a coating layer of inorganic particles. The inorganic
particles included in the coating layer may be coupled to a binder
so that an interstitial volume exists between adjacent inorganic
particles.
[0184] The inorganic particles may include an inorganic material
having a dielectric constant of 5 or more. In a non-limiting
example, the inorganic particles may include at least one material
selected from the group consisting of Pb(Zr,Ti)O.sub.3 (PZT),
Pb.sub.1xLa.sub.xZr.sub.1yTi.sub.yO.sub.3 (PLZT),
PB(Mg.sub.3Nb.sub.2/3)O.sub.3--PbTiO.sub.3 (PMN-PT), BaTiO.sub.3,
hafnia (HfO.sub.2), SrTiO.sub.3, TiO.sub.2, Al.sub.2O.sub.3,
ZrO.sub.2, SnO.sub.2, CeO.sub.2, MgO, CaO, ZnO, and
Y.sub.2O.sub.3.
[0185] An electrolyte may be a salt having a structure such as
A.sup.+B.sup.-. Here, A.sup.+ includes an alkali metal cation such
as Li.sup.+, Na.sup.+, or K.sup.+ or a combination thereof. In
addition, B.sup.- includes at least one anion selected from the
group consisting of F.sup.-, Cl.sup.-, Br.sup.-, I.sup.-,
NO.sub.3.sup.-, N(CN).sub.2.sup.-, BF.sub.4.sup.-, ClO.sub.4.sup.-,
AlO.sub.4.sup.-, AlCl.sub.4.sup.-, PF.sub.6.sup.-, SbF.sub.6.sup.-,
AsF.sub.6.sup.-, BF.sub.2C.sub.2O.sub.4.sup.-,
BC.sub.4O.sub.8.sup.-, (CF.sub.3).sub.2PF.sub.4.sup.-,
(CF.sub.3).sub.3PF.sub.3.sup.-, (CF.sub.3).sub.4PF.sub.2.sup.-,
(CF.sub.3).sub.5PF.sup.-, (CF.sub.3).sub.6P.sup.-,
CF.sub.3SO.sub.3.sup.-, C.sub.4F.sub.9SO.sub.3.sup.-,
CF.sub.3CF.sub.2SO.sub.3.sup.-, (CF.sub.3SO.sub.2).sub.2N.sup.-,
(FSO.sub.2).sub.2N.sup.-, CF.sub.3CF.sub.2(CF.sub.3).sub.2CO.sup.-,
(CF.sub.3SO.sub.2).sub.2CH.sup.-, (SF.sub.5).sub.3C.sup.-,
(CF.sub.3SO.sub.2).sub.3C.sup.-,
CF.sub.3(CF.sub.2).sub.7SO.sub.3.sup.-, CF.sub.3CO.sub.2.sup.-,
CH.sub.3CO.sub.2.sup.-, SCN.sup.-, and
(CF.sub.3CF.sub.2SO.sub.2).sub.2N.sup.-.
[0186] The electrolyte may also be dissolved in an organic solvent.
The organic solvent may use propylene carbonate (PC), ethylene
carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC),
dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile,
dimethoxyethane, diethoxyethane, tetrahydrofuran,
N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC),
.gamma.-butyrolactone, or a mixture thereof.
[0187] The battery housing 20 is a receiving body of a
substantially cylindrical shape having an opening portion at one
side thereof, and includes a metal material having conductivity. A
side surface of the battery housing 20 and a bottom surface of the
battery housing 20, opposite to the opening portion, are generally
integrally formed with each other. That is, the battery housing 20
is generally formed so that an upper end in a height direction is
opened and a lower end except for a central portion is closed. The
bottom surface of the battery housing 20 may have a substantially
flat shape. The battery housing 20 may receive the electrode
assembly 10 through the opening portion formed at one side in the
height direction thereof. The battery housing 20 may also receive
the electrolyte through the opening portion.
[0188] The battery housing 20 may include a beading portion 21 that
is formed on an end portion adjacent to the opening portion and is
press-fitted inward. The battery housing 20 may include a crimping
portion 22 that is formed at a position between the opening portion
and the beading portion 21 and extends and is bent toward the
opening portion.
[0189] In detail, the battery housing 20 may include the beading
portion 21 formed on an upper end portion thereof. The battery
housing 20 may further include the crimping portion 22 formed above
the beading portion 21. The beading portion 21 is formed by
press-fitting an outer circumference of the battery housing 20 to a
certain depth. The beading portion 21 is formed over the electrode
assembly 10. An inner diameter of the battery housing 20 at a
region where the beading portion 21 is formed is less than a
diameter of the electrode assembly 10.
[0190] The beading portion 21 provides a support surface on which
the cap 40 may be mounted. Also, the beading portion 21 may provide
a support surface on which at least a part of a circumferential
edge of the current collector 30 described below may be mounted and
coupled. That is, on a top surface of the beading portion 21, at
least a part of a circumferential edge of the current collector 30
of the present disclosure and/or a circumferential edge of the cap
40 of the present disclosure may be mounted. As shown in FIGS. 2
and 3, in order to stably support at least a part of the
circumferential edge of the current collector 30 and/or the
circumferential edge of the cap 40, at least a part of the top
surface of the beading portion 21 may extend in a direction
substantially parallel to the bottom surface of the battery housing
20, that is, a direction substantially perpendicular to a sidewall
of the battery housing 20.
[0191] The beading portion 21 may include a beading portion top
surface located over an innermost point that is press-fitted
inward; and a beading portion bottom surface located under the
innermost point that is press-fitted inward.
[0192] For example, a press-fitting depth PD of the beading portion
21 may range from about 0.2 mm to about 10 mm. For a minimum value
of the press-fitting depth PD of the beading portion 21, a radius
of curvature R1 of the beading portion 21, a welding bead width
W.sub.bead, and a radius of curvature R2 at a boundary region
between the beading portion 21 and an inner surface of the battery
housing 20 should be considered together. For example, referring to
FIG. 11, in order to enable welding, an additional space in
addition to the radius of curvature R1 of the beading portion 21
and the radius of curvature R2 at the boundary region between the
beading portion 21 and the inner surface of the battery housing 20
is required. This is because, when the press-fitting depth PD is
R1+R2, a flat section F does not exist in the beading portion.
Furthermore, in order to enable welding, an additionally required
space should be equal to or greater than a minimum width
W.sub.bead,min of a welding bead BD. Accordingly, the minimum value
of the press-fitting depth PD satisfies the following relation.
PD.gtoreq.R.sub.1,min+R.sub.2,min+W.sub.bead,min
[0193] For example, minimum values of R.sub.1,min and R.sub.2,min
may each be about 0.05 mm, and W.sub.bead,min may be about 0.1 mm.
In this case, the minimum value of the press-fitting depth PD may
be equal to or greater than about 0.2 mm.
[0194] In another aspect, a maximum value of the press-fitting
depth PD of the beading portion 21 may vary according to a material
and a thickness of the battery housing 20. In an example, when a
material of the battery housing 20 is a steel material and a
maximum thickness of the battery housing 20 is about 1 mm, the
maximum value of the press-fitting depth PD of the beading portion
21 may be about 10 mm. Accordingly, in an embodiment, the
press-fitting depth PD of the beading portion 21 may have a value
between about 0.2 mm and about 10 mm.
[0195] In another aspect of the present disclosure, as shown in
FIG. 1a, at least one of the beading portion top surface and the
beading portion bottom surface may be inclined at a certain angle
with respect to the bottom surface of the battery housing 20.
Alternatively, as shown in FIGS. 2 and 3, at least one of the
beading portion top surface and the beading portion bottom surface
may include a section parallel to the bottom surface of the battery
housing 20 in at least a region. That is, the beading portion top
surface and the beading portion bottom surface may include the flat
section F (see FIG. 3) in at least a part.
[0196] The crimping portion 22 is formed over the beading portion
21. The crimping portion 22 extends and is bent to surround a
circumferential edge of the cap 40 located over the beading portion
21. Due to this bent shape of the crimping portion 22, the cap 40
is fixed to the beading portion 21.
[0197] In another aspect, an innermost point of the beading portion
21 may be located more inside in a radial direction than a distal
point of the crimping portion 22. For example, referring to FIG. 2,
the distal point of the crimping portion 22 may be located more
outside in the radial direction than the innermost point of the
beading portion 21. According to this structure, the flat beading
portion 21 may be maintained even after a sizing process. For
example, if the innermost point of the beading portion 21 is
located more outside in the radial direction than the distal point
of the crimping portion 22, a radial length of a top surface of the
crimping portion 22 would be greater than a radial length of the
beading portion 21. In this case, the area of the top surface of
the crimping portion 22 to which pressure is applied in the sizing
process may be increased, and thus, the beading portion 21 may not
be flat after the sizing process. Accordingly, in the present
disclosure, it is preferable that the innermost point of the
beading portion 21 is located more inside than a distal end of the
crimping portion 22 in the radial direction.
[0198] Also, the crimping portion 22 may be omitted, and the cap 40
may be fixed while covering the opening portion of the battery
housing 20 through another fixing structure. For example, a battery
in which a beading portion is omitted is disclosed in Patent
Application Publication No. KR 10-2019-0030016 A of the present
applicant, which is herein incorporated by reference, and such a
structure may be applied to the present disclosure.
[0199] The current collector (first current collector) 30 according
to an embodiment of the present disclosure will now be described
with reference to FIGS. 3 and 4a.
[0200] First, referring to FIG. 3, the current collector 30
according to an embodiment of the present disclosure is
accommodated in the battery housing 20, and is electrically
connected to the electrode assembly 10 and is also electrically
connected to the battery housing 20. That is, the current collector
30 electrically connects the electrode assembly 10 to the battery
housing 20. Preferably, the current collector 30 may be
electrically coupled to the first uncoated portion 11 and the
beading portion 21 of the battery housing 20. At least one tab
coupling portion 32 of the current collector 30 may be located at a
lower position than the beading portion bottom surface.
[0201] The current collector 30 includes the tab coupling portion
32 coupled to the first uncoated portion 11, and a housing coupling
portion 33 extending from the tab coupling portion 32 and
electrically coupled to the beading portion 21 on an inner surface
of the battery housing 20. A boundary region between the tab
coupling portion 32 and the housing coupling portion 33 may be bent
so that an end portion of the housing coupling portion 33 faces the
beading portion 21. That is, referring to FIG. 2 or the like, the
boundary region between the tab coupling portion 32 and the housing
coupling portion 33 may be bent upward.
[0202] Optionally, the current collector 30 may further include a
central portion 31, in a core region of the current collector 30.
The central portion 31 may have a substantially circular shape. The
central portion 31 may be selectively coupled to the first uncoated
portion 11. In this case, the housing coupling portion 33 may be
press-fixed by the crimping portion 22.
[0203] The current collector 30 may have at least one leg structure
extending in the radial direction in a state where the tab coupling
portion 32 and the housing coupling portion 33 are connected to
each other. Preferably, a plurality of leg structures may be
provided. For example, referring to FIGS. 4a through 6, the current
collector 30 may include four leg structures. When a plurality of
leg structures are provided, a plurality of housing coupling
portions 33 may also be provided. In this case, the plurality of
housing coupling portions 33 may be connected to one another and
may be integrally formed. The leg structures may be arranged in a
radial shape, a cross shape, or a combined shape about the central
portion 31.
[0204] The central portion 31 and at least one tab coupling portion
32 may be located over the electrode assembly 10, and when the
beading portion 21 is formed on the battery housing 20, the central
portion 31 and the at least one tab coupling portion 32 may be
located under the beading portion 21. One or more holes for
injecting an electrolytic solution may be formed in the tab
coupling portion 32.
[0205] When a total radial length of the tab coupling portion 32 is
T, an outer diameter of the electrode assembly 10 is JR, and a
height of an outermost segment 11a of the electrode assembly is F,
the following relation may be satisfied.
JR-2*F.ltoreq.T<JR
[0206] Preferably, the total radial length T of the tab coupling
portion 32 may be equal to or greater than a length obtained by
subtracting the height of the segment 11a located at the outermost
side from the outer diameter of the electrode assembly 10 twice.
When the relation is satisfied, the tab coupling portion 32 covers
an end portion of the segment 11a located at the outermost side.
That is, the current collector 30 may have an outer diameter
covering an end portion of the segment 11a that is bent at a last
winding turn of the first electrode. In this case, welding may be
performed in a state where the segments 11a that form a bent
surface 102 coupled to the tab coupling portion 32 are uniformly
pressed by the current collector 30, and even after the welding, a
close stacked state of the segments 11a may be maintained well. The
close stacked state refers to a state where there is substantially
no gap between the segments as shown in FIG. 1c. The close stacked
state contributes to lower the resistance of the battery 1 to a
level suitable for rapid charging (e.g., 4 mohm) or less.
[0207] In another aspect, the total radial length T of the tab
coupling portion 32 may be less than an outer diameter JR of the
electrode assembly 10. If the total radial length T of the tab
coupling portion 32 is greater than the outer diameter JR of the
electrode assembly 10, a dead space in the battery housing 20 may
be increased, thereby adversely affecting the energy density of the
battery 1. Accordingly, it is preferable that the total radial
length T is less than the outer diameter JR of the electrode
assembly 10.
[0208] The central portion 31 includes a circular current collector
hole H2 formed at a position corresponding to a winding central
hole H1 formed at a central portion of the electrode assembly 10.
The winding central hole H1 and the current collector hole H2
communicating with each other may function as paths for irradiating
a laser welding beam or inserting a welding rod for welding between
the terminal 50 and the current collector (second current
collector) P or welding between the terminal 50 and a lead tabor
paths for irradiating a laser welding beam.
[0209] FIG. 7 is a view for describing a relationship between a
current collector hole and a winding hole.
[0210] Referring to FIG. 7, a diameter of the current collector
hole H2 may be equal to or greater than a diameter of the winding
central hole H1 formed in a core of the electrode assembly 10. For
example, the reason why the diameter of the current collector hole
H2 is set to be greater than the diameter of the winding central
hole H1 formed in the core of the electrode assembly 10 is that it
is necessary to secure a space according to the insertion of a
welding guide, when the laser welding beam is irradiated or the
welding rod is inserted for welding between the terminal 50 and the
current collector (second current collector) P or welding between
the terminal 50 and the lead tab. When the diameter of the current
collector hole H2 is excessively less than the diameter of the
winding central hole H1, the winding central hole H1 may be covered
and may act as an interference factor during continuous resistance
welding (CRW).
[0211] Unlike the embodiment, according to another embodiment of
the present disclosure, the diameter of the current collector H2
may be less than the diameter of the winding central hole H1 formed
in the core of the electrode assembly 10. For example, when the
diameter of the winding central hole H1 is R3, the diameter of the
current collector hole H2 may be equal to or greater than 0.5*R3
and less than R3, and preferably, may be equal to or greater than
0.7*R3 and less than R3.
[0212] In general, when gas is discharged from a winding central
portion during venting, due to strong pressure, a separator or an
uncoated portion at the center of winding may be separated from a
top surface of the electrode assembly 10. In this case, when the
diameter of the current collector hole H2 is less than the diameter
of the winding central hole H1 formed in the core of the electrode
assembly 10, the separator or the uncoated portion at the center of
winding may be prevented from being separated from the top surface
of the electrode assembly 10. However, when the diameter of the
current collector hole H2 is excessively small, the injection of an
electrolytic solution may be degraded, and a space for welding
between the second current collector P and the terminal 50 is
required, and thus, it is preferable that the diameter of the
current collector hole H2 is equal to or greater than 0.5*R3 and it
is more preferable that the diameter of the current collector hole
H2 is equal to or greater than 0.7*R3.
[0213] In another aspect, the central portion 31 may have a
substantially circular plate shape. For example, referring to FIG.
4a, the central portion 31 may have an annular plate shape at the
center of which the current collector hole H2 is formed.
[0214] The at least one tab coupling portion 32 may extend
substantially radially from the central portion 31 of the current
collector 30 to a sidewall of the battery housing 20. For example,
a plurality of tab coupling portions 32 may be provided. For
example, referring to FIG. 4a, the plurality of tab coupling
portions 32 may be spaced apart from one another along a
circumference of the central portion 31. As such, because the
battery 1 of the present disclosure includes the plurality of tab
coupling portions 32, a coupling area with the first uncoated
portion 11 may be increased. Accordingly, a coupling force between
the first uncoated portion 11 and the tab coupling portion 32 may
be secured and electrical resistance may be reduced.
[0215] The tab coupling portion 32 may be welded to the first
uncoated portion 11. Examples of a welding method include, but are
not limited to, laser welding, resistance welding, and ultrasonic
welding. The tab coupling portion 32 may be welded to the first
uncoated portion 11 while being parallel to the bottom surface of
the battery housing 20. The first uncoated portion 11 and the tab
coupling portion 32 may be welded in the radial direction of the
electrode assembly 10.
[0216] FIG. 1b is a longitudinal sectional view illustrating a part
of a battery, according to another embodiment of the present
disclosure. FIG. 1c is an enlarged view illustrating an upper
portion of the electrode assembly 10 of FIG. 1b. FIG. 1d is an
enlarged view illustrating an upper portion of the first uncoated
portion 11 of FIG. 1c.
[0217] Referring to FIG. 1b, in a state where the tab coupling
portion 32 is mounted on an end portion of the first uncoated
portion 11, welding may be performed on a certain region.
Alternatively, at least a part of the first uncoated portion 11 may
include a plurality of segments 11a in a winding direction of the
electrode assembly 10. The plurality of segments 11a may be bent in
a radial direction of the electrode assembly 10 to form the bent
surface 102. The radial direction of the electrode assembly refers
to a direction toward a core or an outer circumference. For
example, as shown in FIG. 1b, at least part of the first uncoated
portion 11 may include a plurality of segments 11a divided in the
winding direction of the electrode assembly 10. The plurality of
segments 11a may be bent toward the core of the electrode assembly
10. Referring to FIGS. 1c and 1d, the plurality of segments 11a may
overlap in multiple layers in the radial direction of the electrode
assembly 10. The bent surface 102 may include a stack number
increasing section in which the number of overlapping layers of the
segments 11a is sequentially increased to a maximum value from the
outer circumference of the electrode assembly 10 to the core and a
stack number uniform section from a radius point at which the
number of overlapping layers is the maximum value to a radius point
at which an innermost segment exists.
[0218] In this case, in a state where the tab coupling portion 32
is mounted on the bent surface 102 of the first uncoated portion
11, welding may be performed on a certain region. That is, the tab
coupling portion 32 may be coupled to a region where the plurality
of segments 11a overlap in multiple layers. For example, the tab
coupling portion 32 may be coupled to the bent surface to overlap
the stack number uniform section. Referring to FIG. 1d, welding
between the tab coupling portion 32 and the first uncoated portion
11 may be performed on a region of the bent surface 102 of the
first uncoated portion 11 where the number of overlapping layers of
the first uncoated portion 11 is 10 or more. A radial ratio of a
section in which the number of overlapping layers is 10 or more may
be designed to be 25% or more based on a radius of the electrode
assembly excluding the core, by adjusting a length of the first
uncoated portion 11.
[0219] When the current collector 30 is welded to the bent surface
102 of the first uncoated portion 11, it is preferable to increase
an output of a laser in order to sufficiently secure welding
strength. When the output of the laser is increased, the laser may
pass through a region where the first uncoated portion 11 overlaps
and may penetrate into the electrode assembly 10, thereby damaging
the separator or the active material layer. Accordingly, in order
to prevent penetration of the laser, it is preferable to increase
the number of overlapping layers of the first uncoated portion 11
to a certain level or more. In order to increase the number of
overlapping layers of the first uncoated portion 11, a height of
the segment 11a should be increased. However, when the height of
the segment 11a is increased, a swell may occur in the first
uncoated portion 11 in a process of manufacturing the first
electrode current collector. Accordingly, it is preferable that the
height of the segment 11a is adjusted to an appropriate level.
[0220] As described above, when a radial length ratio of the
segment of the uncoated portion in which the number of overlapping
layers is 10 or more is designed to be 25% or more based on a
radius of the electrode assembly and the current collector 30 and a
region where the segment of the uncoated portion overlaps in 10 or
more layers are laser welded, even when an output of a laser is
increased, the overlapping portion of the uncoated portion may
sufficiently mask the laser, thereby preventing damage to the
separator and the active material layer due to the laser.
[0221] Preferably, the output of the laser may be appropriately
adjusted in a range of about 250 W to about 320 W or in a range of
about 40% to about 90% of a maximum laser output specification, but
the present disclosure is not limited thereto. When the output of
the laser satisfies the numerical range, welding strength may be
sufficiently increased. In an embodiment, welding strength may be
increased to be 2 kgf/cm.sup.2 or more, and more particularly, to 4
kgf/cm.sup.2 or more. The welding strength may be set to 8
kgf/cm.sup.2 or less, and more particularly, set to 6 kgf/cm.sup.2
or less. The welding strength is defined as a tensile force per
unit area (kgf/cm.sup.2) of the current collector 30 when the
current collector begins to be separated from the bent surface
region. In detail, a tensile force is applied to the current
collector after welding of the current collector is completed, and
a magnitude thereof is gradually increased. When the tensile force
is increased, the uncoated portion begins to be separated from a
welding interface. In this case, a value obtained by dividing the
tensile force applied to the current collector by the area of the
current collector is the welding strength.
[0222] FIG. 1d is a partial cross-sectional view illustrating a
bent surface region where, in an electrode assembly having a radius
of 22 mm and a core radius of 4 mm and included in a battery having
a form factor of 4680, the first uncoated portion 11 of the first
electrode current collector divided into a plurality of segments is
bent from an outer circumference to a core to overlap in 10 or more
layers. In FIG. 1d, an electrode assembly region and a core region
with no segments are not shown. A height of the segments starts
from 3 mm and is increased by 1 mm whenever a radius of the
electrode assembly is increased by 1 mm. After reaching a length 6
mm, 7 mm, or 8 mm in FIG. 1d, the height of the segments remains
substantially the same.
[0223] Referring to FIG. 1d it is found that the number of
overlapping layers of the first uncoated portion 11 is gradually
increased from the outer circumference to the core, and as the
length of the first uncoated portion 11 is increased, a maximum
value of the number of overlapping layers is increased.
[0224] For example, when the length of the first uncoated portion
11 is 8 mm, the number of overlapping layers of the first uncoated
portion 11 divided into a plurality of segments is increased to 18
in an interval from the outer circumference to 7 mm, is maintained
at the maximum value of 18 in an interval further 8 mm toward the
core, and is reduced by 1 or 2 in a radius interval adjacent to the
core. The height of the segment is increased stepwise from 3 mm to
8 mm in a radius interval from 7 mm to 12 mm. In the present
disclosure, the stack number uniform section is defined as a radius
interval from a radius point at which the number of overlapping
layers reaches a maximum value to a point at which an innermost
segment is located as shown in FIG. 1d. Accordingly, a ratio of the
stack number uniform section in which the segments 11a of the first
uncoated portion 11 overlap in 10 or more layers is 44.4% (8/18)
with respect to the radius of the electrode assembly excluding the
core (4 mm).
[0225] In another example, when the length of the first uncoated
portion 11 is 7 mm, the number of overlapping layers of the first
uncoated portion 11 divided into a plurality of segments is
increased to 15 in an interval from the outer circumference of the
electrode assembly to 6 mm, is maintained at the maximum value of
15 in an interval further 9 mm toward the core, and is reduced by 1
or 2 in a radius interval adjacent to the core. The height of the
segment is increased stepwise from 3 mm to 7 mm in a radius
interval from 7 mm to 11 mm. Accordingly, a ratio of the stack
number uniform section in which the segments 11a of the first
uncoated portion 11 overlap in 10 or more layers is 50% (9/18) with
respect to the radius of the electrode assembly excluding the core
(4 mm).
[0226] In another example, when the length of the first uncoated
portion 11 is 6 mm, the number of overlapping layers of the first
uncoated portion 11 divided into a plurality of segments is
increased to 12 in an interval from the outer circumference of the
electrode assembly to 5 mm, is maintained at the maximum value of
12 in an interval further 10 mm toward the core, and is reduced by
1 or 2 in a radius interval adjacent to the core. The height of the
segment is increased from 3 mm to 6 mm in a radius interval from 7
mm to 10 mm. Accordingly, a ratio of the stack number uniform
section in which the segments 11a of the first uncoated portion 11
overlap in 10 or more layers is 55.6% (10/18) with respect to the
radius of the electrode assembly excluding the core (4 mm).
[0227] According to an embodiment, it is found that a length of a
section in which the number of overlapping layers is sequentially
increased is increased from 5 mm to 7 mm as a length of the first
uncoated portion 11 is increased, and in particular, a condition
that a ratio of the stack number uniform section in which the
number of overlapping layers is 10 or more is 25% or more based on
a radius of an electrode assembly excluding a core is
satisfied.
[0228] In the present disclosure, the stack number uniform section
may be increased or decreased by a radius of the core, a minimum
value and a maximum value of a height of the segment in a segment
height variable interval, and a height increment of the segment in
a radial direction of the electrode assembly. Accordingly, it is
obvious to one of ordinary skill in the art that the ratio is
designed to be 25% or more by adjusting factors affecting the ratio
of the stack number uniform section. In an example, when both the
minimum value and the maximum value of the height of the segment
are increased in the segment height variable interval, the number
of stacked layers may be increased and the ratio of the stack
number uniform section may be reduced to about 25%.
[0229] The stack number uniform section is a region where a current
collector may be welded. Accordingly, when the ratio of the stack
number uniform section is adjusted to be 25% or more, the welding
strength of the current collector may be secured within a desirable
range and it may be advantageous in terms of the resistance of a
welding interface.
[0230] In another aspect of the present disclosure, when the first
uncoated portion 11 has such a bent shape, a space occupied by the
first uncoated portion 11 may be reduced, thereby improving energy
density. Also, because a coupling area between the first uncoated
portion 11 and the current collector 30 is increased, a coupling
force may be improved and resistance may be reduced.
[0231] FIGS. 8a through 10 are views for describing a welding
region between the current collector 30 and the first uncoated
portion 11.
[0232] Referring to FIGS. 8a through 10, a welding bead BD may be
formed in a welding region between the first uncoated portion 11
and the tab coupling portion 32. The welding bead BD refers to a
substantially circular welding portion formed when spot welding is
performed at a specific point. For example, in FIG. 11, the welding
bead BD having a substantially circular shape formed as a result of
spot welding is illustrated. When a plurality of welding beads BD
are connected, a specific welding pattern may be formed. For
example, referring to FIG. 8a, the plurality of welding beads BD
may be gathered to form a substantially linear welding pattern. In
an embodiment, the plurality of welding beads BD formed between the
first uncoated portion 11 and the tab coupling portion 32 may form
a welding pattern extending in a radial direction of the electrode
assembly 10. Preferably, the welding beads BD formed between the
first uncoated portion 11 and the tab coupling portion 32 may form
a linear welding pattern extending in the radial direction of the
electrode assembly 10. For example, a welding pattern formed
between the first uncoated portion 11 and the tab coupling portion
32 may have a linear shape in which spot welding is connected. A
width of the welding bead BD formed between the first uncoated
portion 11 and the tab coupling portion 32 may be equal to or
greater than about 0.1 mm. This is because, when laser technology
is considered, a minimum width of the welding bead BD is equal to
or greater than about 0.1 mm.
[0233] A longitudinal end portion of the tab coupling portion 32
may be located more inside than an innermost point of the beading
portion 21 formed on the battery housing 20. In more detail, a
boundary region between the tab coupling portion 32 and the housing
coupling portion 33 may be located more inside in a direction
toward the winding central hole H1 than the innermost point of the
beading portion 21 formed on the battery housing 20. According to
this structure, damage to a coupling portion between components
which may occur when the current collector 30 is excessively bent
in order to locate an end portion of the housing coupling portion
33 on the beading portion 21 may be prevented. In other words, when
viewed along a longitudinal axis of the battery housing 20, the at
least one tab coupling portion 32 may not overlap the beading
portion 21.
[0234] In order to secure a coupling force and reduce electrical
resistance by increasing a coupling area between the current
collector 30 and the electrode assembly 10, not only the tab
coupling portion 32 but also the central portion 31 may be coupled
to the first uncoated portion 11. An end portion of the first
uncoated portion 11 may be bent to be parallel to the tab coupling
portion 32. As such, when the end portion of the first uncoated
portion 11 is bent and coupled to the tab coupling portion 32 to be
parallel to the tab coupling portion 32, a coupling area may be
increased, a coupling force may be improved, and electrical
resistance may be reduced. Also, a total height of the electrode
assembly 10 may be minimized and energy density may be
improved.
[0235] The at least one housing coupling portion 33 may extend from
an end portion of the tab coupling portion 32 and may be coupled to
the beading portion 21 on an inner surface of the battery housing
20. For example, the at least one housing coupling portion 33 may
extend from the end portion of the tab coupling portion 32 to a
sidewall of the battery housing 20. A plurality of housing coupling
portions 33 may be provided. For example, referring to FIG. 4a, the
plurality of housing coupling portions 33 may be spaced apart from
one another along a circumference of the central portion 31.
Referring to FIG. 1a, the plurality of housing coupling portions 33
may be coupled to the beading portion 21 on the inner surface of
the battery housing 20. As shown in FIGS. 2 and 3, when a top
surface of the beading portion 21 extends in a direction
substantially parallel to a bottom surface of the battery housing
20, that is, a direction substantially perpendicular to the
sidewall of the battery housing 20, and the housing coupling
portion 33 also extends in the same direction, the housing coupling
portion 33 may stably contact the beading portion 21. Also, as
such, when the housing coupling portion 33 stably contacts the
beading portion 21, welding between two components may be smoothly
performed, and thus, a coupling force between the two components
may be improved and an increase in resistance at a coupling portion
may be minimized. Also, due to such a structure in which the
current collector 30 is coupled to the beading portion 21 of the
battery housing 20, not an inner surface of a cylindrical portion
of the battery housing 20, a distance between the current collector
30 and the beading portion 21 may be reduced. Accordingly, a dead
space inside the battery housing 20 may be minimized and the energy
density of the battery 1 may be improved.
[0236] Referring to FIGS. 3 and 4a, the housing coupling portion 33
includes a contact portion 33a that is coupled to the beading
portion 21 on an inner surface of the battery housing 20 and a
connecting portion 33b that connects the tab coupling portion 32 to
the contact portion 33a.
[0237] The contact portion 33a is coupled to the inner surface of
the battery housing 20. When the beading portion 21 is formed on
the battery housing 20, the contact portion 33a may be coupled to
the beading portion 21 as described above. In this case, as
described above, for stable contact and coupling, the beading
portion 21 and the contact portion 33a may extend in a direction
substantially parallel to a bottom surface of the battery housing
20, that is, a direction substantially perpendicular to a sidewall
of the battery housing 20. The contact portion 33a may have a flat
surface coupled to a top surface of the beading portion 21 facing
the opening portion. That is, the contact portion 33a includes at
least a flat portion substantially parallel to the bottom surface
of the battery housing 20.
[0238] In an embodiment of the present disclosure, referring to
FIG. 13f, the connecting portion 33b may have an upwardly convex
structure. For example, the connecting portion 33b may have an
upwardly convex curved shape. Alternatively, as shown in FIG. 13f,
the connecting portion 33b may include at least one bent part C.
Preferably, when viewed along a longitudinal axis of the battery
housing, the at least one bent part C may be bent at an obtuse
angle so as not to overlap. More preferably, a boundary point
between the contact portion 33a and the connecting portion 33b may
be bent at an obtuse angle. That is, as shown in FIG. 13f, an
inclination of the connecting portion 33b may be reduced stepwise
or gradually toward the beading portion.
[0239] In another embodiment of the present disclosure, referring
to FIG. 4a, the connecting portion 33b may include at least one
bending portion B whose extension direction is changed at least
once between the central portion 31 and the contact portion 33a.
That is, the connecting portion 33b may have a structure that may
be contracted and extended within a certain range, for example, a
spring-like structure or a bellows-like structure. The connecting
portion 33b may be elastically biased upward by the bending portion
B. According to this structure of the connecting portion 33b, even
when there is a height distribution of the electrode assembly 10
within a certain range, the contact portion 33a may be in close
contact with the beading portion 21 in a process of accommodating
the electrode assembly 10 to which the current collector 30 is
coupled in the battery housing 20. Also, according to this
structure of the connecting portion 33b, a shape may be more stably
achieved during a sizing process.
[0240] In another embodiment of the present disclosure, as shown in
FIGS. 2 and 3, a connected portion between the contact portion 33a
and the connecting portion 33b may be bent. Alternatively, as shown
in FIG. 1a, a connected portion between the contact portion 33a and
the connecting portion 33b may have a complementary shape
corresponding to an inner surface of the beading portion 21. In
particular, the connected portion between the contact portion 33a
and the connecting portion 33b may be coupled to the beading
portion 21 with no gap while having a shape matching the inner
surface of the beading portion 21. According to this structure, the
beading portion 21 may effectively support the current collector
30. Also, according to this structure, unnecessary interference
between the beading portion 21 and the connecting portion 33b may
be prevented. Accordingly, stable coupling between the contact
portion 33a and the beading portion 21 may be effectively
maintained.
[0241] According to another aspect of the present disclosure, a
protruding outermost point of the bending portion B may be spaced
by a certain interval from an innermost point of the beading
portion 21. For example, referring to FIG. 3, the bending portion B
may not contact the beading portion 21. According to this
structure, unnecessary interference between the beading portion 21
and the connecting portion 33b may be prevented. Accordingly,
stable coupling between the contact portion 33a and the beading
portion 21 may be effectively maintained.
[0242] According to another aspect of the present disclosure, due
to the bending portion B, an angle between the contact portion 33a
and the connecting portion 33b may be an acute angle. For example,
referring to FIGS. 2, 4b, and 8b, the connecting portion 33b does
not include a bending portion. Accordingly, an angle between the
contact portion 33a and the connecting portion 33b may be an obtuse
angle. In contrast, referring to FIGS. 3 and 4a, the connecting
portion 33b includes a bending portion. Accordingly, an angle
between the contact portion 33a and the connecting portion 33b may
be an acute angle. According to this structure, because an angle
between the contact portion 33a and the connecting portion 33b is
an acute angle, interference between the beading portion 21 and the
connecting portion 33b may be prevented. Accordingly, stable
coupling between the contact portion 33a and the beading portion 21
may be maintained. Although one bending portion B is provided in
the drawings of the present disclosure, the present disclosure is
not limited thereto and a plurality of bending portions B may be
provided.
[0243] It is preferable that a vertical distance between the
contact portion 33a and the central portion 31 in a state where an
external force is not applied to the current collector 30 and thus
there is no deformation is equal to a vertical distance between a
top surface of the beading portion 21 and the central portion 31
when the electrode assembly 10 to which the current collector 30 is
coupled is mounted in the battery housing 20 or is smaller within a
range in which the connecting portion 33b is stretchable. In a case
where the connecting portion 33b is configured to satisfy the above
condition, when the electrode assembly 10 to which the current
collector 30 is coupled is mounted in the battery housing 20, the
contact portion 33a may naturally be in close contact with the
beading portion 21.
[0244] In addition, according to such a contractible and
stretchable structure of the connecting portion 33b, even when
vibration and/or impact occurs during the use of the battery 1 and
thus the electrode assembly 10 vertically moves, impact according
to the movement of the electrode assembly 10 may be reduced, within
a certain range.
[0245] In another aspect of the present disclosure, the connecting
portion 33b may have an upwardly convex curved shape. For example,
the connecting portion 33b may protrude toward a winding center of
the electrode assembly 10. A shape of the connecting portion 33b is
determined to prevent damage to a coupling portion between the
current collector (first current collector) 30 and the electrode
assembly 10 and/or a coupling portion between the current collector
(first current collector) 30 and the battery housing 20 during a
sizing process.
[0246] FIGS. 13a through 13d are views for describing a process of
manufacturing the battery 1 of the present disclosure.
[0247] FIG. 13a is a view for describing a welding process of the
current collector 30. After the current collector 30 is placed on
the electrode assembly 10 that is accommodated in the battery
housing 20, a process of welding the current collector 30 and the
first uncoated portion 11 of the electrode assembly 10 which
protrudes upward is illustrated. In this case, the tab coupling
portion 32 of the current collector 30 is welded to a bent surface
formed by the plurality of segments 11a of the first uncoated
portion 11.
[0248] Next, FIG. 13b is a view for describing a beading process of
the battery housing 20. In a state where the current collector 30
is welded to the electrode assembly 10, a beading knife may move
toward the inside of the battery housing 20. Accordingly, the
beading portion 21 formed by press-fitting a part of the battery
housing 20 into the battery housing 20 is provided on a side
surface of the battery housing 20. Because the beading portion 21
is located under than the contact portion 33a of the current
collector 30, an inner surface of the beading portion 21 and the
contact portion 33a may be welded to each other.
[0249] Next, FIG. 13c is a view for describing a crimping process
of the battery housing 20. The contact portion 33a of the current
collector 30 may be placed on a top surface of the beading portion
21. The cap 40 whose end portion is surrounded by the sealing
gasket G1 may be placed on a top surface of the contact portion
33a. Next, the battery housing 20 is bent to surround a
circumferential edge of the cap 40, and fixes the cap 40 and the
current collector 30. Due to this bent shape of the crimping
portion 22, the cap 40 and the current collector 30 are fixed to
the beading portion 21.
[0250] Next, FIG. 13d is a view for describing a sizing process of
the battery housing 20. A sizing process is a compression process
for reducing a height of the beading portion 21 of the battery
housing 20 in order to reduce a total height of the battery 1, when
the battery 1 is manufactured. According to the sizing process,
because the battery housing 20 is compressed in a longitudinal
direction, a part of the electrode assembly 10 may be compressed by
the beading portion 21. In another aspect, according to the sizing
process, because the battery housing 20 is compressed in the
longitudinal direction (vertical direction), the current collector
30 may be vertically bent under pressure. That is, the tab coupling
portion 32 may be bent upward, and thus, welding between the tab
coupling portion 32 and the first uncoated portion 11 may be likely
to be damaged. Accordingly, there is a demand for a shape of the
current collector 30 in which a welding region between the tab
coupling portion 32 and the first uncoated portion 11 is not
damaged even after the sizing process.
[0251] For example, when the connecting portion 33b has an upwardly
convex shape as shown in FIG. 13f, upward lifting of the tab
coupling portion 32 may be suppressed as much as possible as shown
in FIG. 13d. That is, when the battery housing 20 of FIG. 13c is
vertically compressed, the current collector 30 of the present
disclosure vertically receives stress. However, because the
connecting portion 33b of the current collector 30 of the present
disclosure has an upwardly convex shape, stress applied to the tab
coupling portion 32 may be minimized. Accordingly, the tab coupling
portion 32 may not be bent upward, and good welding with the first
uncoated portion 11 may be maintained.
[0252] In more detail, referring to FIGS. 13f and 13g, the
connecting portion 33b before a sizing process may have an upwardly
convex shape based on an imaginary straight line that connects an
end portion of the contact portion 33a to an end portion of the tab
coupling portion 32. For example, at least one bent part C having
an obtuse angle may be provided on the connecting portion 33b. The
bent part C may be located over an imaginary plane that passes
through the center of the imaginary straight line that connects the
end portion of the contact portion 33a to the end portion of the
tab coupling portion 32, and is parallel to a bottom surface of the
battery housing 20. Preferably, a length of the connecting portion
33b between the tab coupling portion 32 and the bent part C may be
greater than a length of the connecting portion 33b between the
contact portion 33a and the bent part C.
[0253] According to this structure, during the sizing process of
receiving pressure in a vertical direction, the contact portion 33a
moves downward in an arrow direction and the connecting portion 33b
is uplifted upward in an arrow direction (see dashed line). In more
detail, the connecting portion 33b is uplifted upward to be over
the beading portion 21. That is, a profile of the housing coupling
portion 33 is changed before and after the sizing process as shown
in FIG. 13f. A degree to which the connecting portion 33b is
uplifted upward varies according to a change in a height of the
battery housing 20 during the sizing process. Unlike in the
drawing, a position of the bent part C may move upward only up to a
height of the contact portion 33a. As such, because the connecting
portion 33b may absorb most of stress due to the upward movement of
the connecting portion 33b, stress applied to a welding region
between the tab coupling portion 32 and the first uncoated portion
11 is relatively small. Accordingly, according to the present
disclosure, a phenomenon where the tab coupling portion 32 is
lifted upward may be prevented. Also, according to the above
structure, because a length of the connecting portion 33b between
the tab coupling portion 32 and the bent part C is greater than a
length of the connecting portion 33b between the contact portion
33a and the bent part C, the insertion of the current collector 30
into the battery housing 20 may be facilitated and stress
distribution may be effectively achieved.
[0254] In another embodiment of the present disclosure, referring
to FIG. 13g, a profile of the battery collector plate 30 after a
sizing process may be deformed to be different from that in FIG.
13f For example, in FIG. 13f, the connecting portion 33b may be
deformed into an upwardly convex curved shape after the sizing
process, whereas in FIG. 13g, the connecting portion 33b may be
deformed into a straight line shape that is bent at the bent part
C. In more detail, in FIG. 13g, after the sizing process, the
connecting portion 33b may be deformed to be upwardly convex while
each of a part of the connecting portion 33b between the tab
coupling portion 32 and the bent part C and a part of the
connecting portion 33b between the contact portion 33a and the bent
part C maintains a straight line shape.
[0255] As a result of examining a shape of the current collector 30
capable of preventing distortion and/or lifting of the current
collector 30, the present inventors have found that, when the
connecting portion 33b has an upwardly convex structure, damage to
welding between the tab coupling portion 32 and the first uncoated
portion 11 is significantly reduced.
[0256] FIG. 13e is a view illustrating a degree of damage to a
welding region of the current collector 30 after a sizing process
according to a shape of the current collector 30 before a sizing
process.
[0257] Referring to FIG. 13e, Experimental Example 1 is an
experimental example in which the connecting portion 33b before
sizing had a straight line shape. Experimental Example 2 is an
experimental example in which the connecting portion 33b before
sizing was convex downward. Experimental Example 3 is an
experimental example in which the connecting portion 33b before
sizing was convex upward. As a result of performing a 1 mm-sizing
process for Experimental Examples 1 through 3, in Experimental
Example 1 in which the connecting portion 33b had a straight line
shape, a welding region with the tab coupling portion 32 was lifted
by about 0.72 mm. In Experimental Example 2 in which the connecting
portion 33b was convex downward, a welding region with the tab
coupling portion was lifted by about 0.99 mm. That is, it was found
that when the connecting portion 33b was convex downward, a lifting
phenomenon was increased compared to when the connecting portion
33b had a straight line shape. In Experimental Example 3 in which
the connecting portion 33b was convex upward, a welding region with
the tab coupling portion 32 was lifted by about 0.02 mm. It means
that a lifting phenomenon was significantly reduced compared to
Experimental Examples 1 and 2. That is, in Experimental Example 3
in which the connecting portion 33b was convex upward, it was found
that damage to a welding region between the tab coupling portion
and the first uncoated portion was minimized. This is because a
degree of lifting of the current collector 30 is affected by stress
applied by the current collector 30 to the electrode assembly 10.
That is, in Experimental Example 1 in which the connecting portion
33b had a straight line shape and Experimental Example 2 in which
the connecting portion 33b was convex downward, because stress
applied to a welding portion between the current collector 30 and
the electrode assembly 10 in a sizing process was about 4.5 MPa and
about 3.7 MPa which were very large, it was found that a lifting
phenomenon of the current collector 30 was severe. In contrast, in
Experimental Example 3 in which the connecting portion 33b was
convex upward, because stress applied to a welding portion between
the current collector 30 and the electrode assembly 10 in a sizing
process was about 2.0 MPa which was lower than those in
Experimental Examples 1 and 2, it was found that a lifting
phenomenon of the current collector 30 was relatively small.
[0258] Accordingly, preferably, as shown in FIG. 13f, a gradient of
the connecting portion 33b may not be constant and a gradient of an
upper portion may be less than a gradient of a lower portion based
on a certain point (e.g., the bent part C). The certain point may
be located above a middle point of the connecting portion 33b.
Alternatively, the connecting portion 33b may have an upwardly
convex shape based on an imaginary straight line that connects the
tab coupling portion 32 to the contact portion 33a. The convex
shape may be a shape in which a straight line and a straight line
are connected, a curved shape, or a combined shape thereof. In an
example, as shown in FIG. 13f, the connecting portion 33b may
include at least one bent part C based on the certain point.
Preferably, the at least one bent part C may be bent at an obtuse
angle so as not to overlap, when viewed along a longitudinal axis
of the battery housing 20. In another modified example, an
inclination of the connecting portion 33b may be reduced stepwise
or gradually toward the beading portion 21.
[0259] In another aspect of the present disclosure, referring to
FIG. 13d, an angle .theta. between the tab coupling portion 32 and
the connecting portion 33b may range from, for example, 0.degree.
to 90.degree.. For example, when a height of an upper end of the
electrode assembly 10 is increased to correspond to a height of the
beading portion 21 in a sizing process, the tab coupling portion 32
and the contact portion 33a may be located at the same height. That
is, in this case, the angle .theta. between the tab coupling
portion 32 and the connecting portion 33b is 0.degree.. Even when
the sizing process is performed, it is not preferable that the
contact portion 33a is located under the tab coupling portion 32.
This is because, in this case, the first uncoated portion 11 may be
excessively pressed by the beading portion 21 to be damaged.
Accordingly, it is preferable that the angle .theta. between the
tab coupling portion 32 and the connecting portion 33b is equal to
or greater than 0.degree.. In another aspect, the angle .theta.
between the tab coupling portion 32 and the connecting portion 33b
may be increased up to 90.degree. according to a shape in which a
length, a thickness, or a gradient of the connecting portion 33b is
changed stepwise or gradually. However, in order to avoid contact
with the cap 40, it is not preferable that the angle .theta.
exceeds 90.degree..
[0260] In another aspect of the present disclosure, the connecting
portion 33b may support the cap 40. For example, the connecting
portion 33b may be bent upward due to a sizing process. In this
case, the connecting portion 33b that is bent upward may contact
the cap 40. In this case, the connecting portion 33b may support
the cap 40 upward. Accordingly, the current collector 30 may be
firmly fixed in a vertical direction due to the sizing process.
Accordingly, even when vibration and/or impact occurs during the
use of the battery 1, because the current collector 30 fixes the
electrode assembly 10 in the vertical direction, unnecessary
vertical movement of the electrode assembly 10 inside the battery
housing 20 may be prevented.
[0261] In another aspect of the present disclosure, a beading
portion top surface and a beading portion bottom surface may be
asymmetric with respect to an imaginary reference plane that passes
through an innermost point of the beading portion 21 to be parallel
to a bottom surface of the battery housing. For example, referring
to FIG. 13d, because the battery housing 20 is compressed in the
vertical direction due to the sizing process, the beading portion
21 is also compressed in the vertical direction. Accordingly, the
beading portion top surface and the beading portion bottom surface
may be asymmetric with respect to the imaginary reference plane
that passes through the innermost point of the beading portion
21.
[0262] In another aspect of the present disclosure, a press-fitting
depth of the beading portion 21 may be defined as PD. For example,
referring to FIG. 11, a distance from an inner surface of the
battery housing 20 to an innermost point of the beading portion 21
may be defined as the press-fitting depth PD. Meanwhile, a shortest
distance from an end portion of the contact portion 33a to a
vertical line that passes through the innermost point of the
beading portion 21 may be defined as an overlap length OV. That is,
referring to FIG. 11, when the beading portion 21 is projected in a
vertical direction, the overlap length OV refers to a radial length
of a region where the projection and the current collector 30
overlap each other. In this case, the battery 1 of the present
disclosure may satisfy the following relation.
(R.sub.1,min+W.sub.bead,min)/PD.sub.max.ltoreq.OV/PD.ltoreq.(PD.sub.max--
R.sub.2,min)/PD.sub.max
[0263] In order for the contact portion 33a of the current
collector 30 to be weldably placed on the beading portion 21, it is
preferable that the ratio is equal to or greater than
(R.sub.1,min+W.sub.bead,min)/PD.sub.max. Referring to FIG. 11, in
order for the contact portion 33a of the current collector 30 to be
weldably placed on the beading portion 21, a region that is
overlapped more than the radius of curvature R1 of the beading
portion 21 is required. For example, when the contact portion 33a
overlaps only by the radius of curvature R1 of the beading portion
21, the flat section F does not exist, and thus, the contact
portion 33a may contact the beading portion 21 at only one contact
point. That is, the contact portion 33a may not be stably placed on
the beading portion 21. Accordingly, the contact portion 33a
requires a region that is additionally overlapped in addition to
the radius of curvature R1 of the beading portion 21. In this case,
it is preferable that a length of the region that is additionally
overlapped is equal to or greater than the welding bead width
W.sub.bead. That is, the contact portion 33a and the beading
portion 21 may substantially overlap in the region that is
additionally overlapped, and welding may be performed in this
region. Accordingly, when the length of the region that is
additionally overlapped is equal to or greater than the welding
bead width W.sub.bead, stable welding may be performed without
departing from the overlapped region. That is, a minimum overlap
length required for the contact portion 33a to be weldably placed
on the beading portion 21 is R.sub.1,min+W.sub.bead,min.
[0264] In another aspect, in order for the contact portion 33a of
the current collector 30 to be weldably placed on the beading
portion 21, it is preferable that the ratio is equal to or less
than (PD.sub.max-R.sub.2,min)/PD.sub.max. Referring to FIG. 11,
there is the radius of curvature R2 at a boundary region between
the beading portion 21 and an inner surface of the battery housing
20. Accordingly, when the contact portion 33a of the current
collector 30 moves to the boundary region between the inner surface
of the battery housing 20 and the beading portion 21 at which the
radius of curvature R2 is formed, the contact portion 33a is lifted
without being closely attached to the beading portion 21 due to the
radius of curvature R2. Accordingly, a maximum overlap length
required for the contact portion 33a to be closely placed on the
beading portion 21 is PD.sub.max-R.sub.2,min.
[0265] In an example, a maximum value PD.sub.max of the
press-fitting depth PD of the beading portion 21 may be about 10
mm, minimum values R.sub.1,min and R.sub.2,min may each be about
0.05 mm, and W.sub.bead,min may be about 0.1 mm. In this case, a
ratio of the overlap length OV to the press-fitting depth PD of the
beading portion 21 may range from about 1.5% to about 99.5%. In
order for the contact portion 33a of the current collector 30 to be
weldably placed on the beading portion 21, it is preferable that
the ratio is equal to or greater than about 1.5%. A lower limit of
the OV/PD ratio may be determined from the maximum value PD.sub.max
of the press-fitting depth of the beading portion, the minimum
value R.sub.1,min of the radius of curvature R1, and a minimum
width of the contact portion 33a that should contact a top surface
of the beading portion 21 for welding of the contact portion 33a,
that is, a length of the minimum width W.sub.bead,min of the
welding bead BD. In detail, in an example, the maximum value
PD.sub.max of the press-fitting depth may be 10 mm, the minimum
contact width of the contact portion 33a required for welding of
the contact portion 33a, that is, a length of the minimum width
W.sub.bead,min of the welding bead BD may be 0.1 mm, and the
minimum value R.sub.1,min of the radius of curvature R1 may be 0.05
mm. In this condition, because a minimum value of the overlap
length OV is 0.15 mm (=0.1 mm+0.05 mm) and PD.sub.max is 10 mm, a
lower limit of the OV/PD ratio is 1.5%. Meanwhile, a point at which
the contact portion 33a of the current collector 30 may contact
with a maximum width on a flat portion of the beading portion top
surface is a point spaced by the radius of curvature R2 from an
inner surface of the battery housing. Accordingly, when an end
portion of the contact portion 33a is located at the point, the
overlap length OV is maximized. An upper limit of the OV/PD ratio
may be determined from the maximum value of the press-fitting depth
and the minimum value R.sub.2,min of the radius of curvature R2. In
detail, the maximum value of the press-fitting depth may be 10 mm,
and the minimum value of the radius of curvature R2 may be0.05 mm.
In this condition, because the maximum value of the overlap length
OV is 9.95 mm (=10 mm-0.05 mm) and PD.sub.max is 10 mm, an upper
limit of the OV/PD ratio is 99.5%.
[0266] In another aspect of the present disclosure, a welding
position where the beading portion 21 and the contact portion 33a
are welded may be defined as W. In more detail, the welding
position W may refer to a distance from an innermost point of the
beading portion 21 to a central point of an outermost welding bead
BD in a radial direction. In this case, the welding position W and
the press-fitting depth PD may satisfy the following relation.
(OV.sub.min-0.5*W.sub.bead,min)/PD.sub.max.ltoreq.W/PD.ltoreq.(OV.sub.ma-
x-0.5*W.sub.bead,min)/PD.sub.max
[0267] The welding position W of the beading portion 21 and the
contact portion 33a may be determined from an overlap length of the
contact portion 33a and the beading portion 21 and the minimum
width W.sub.bead,min of the welding bead BD. The welding position W
is a central point of the welding bead BD.
[0268] Referring to FIG. 11, a welding position when the contact
portion 33a is minimally placed on the beading portion 21 may be
defined as W1. An overlap length in this case is OV.sub.min as
described above. Because welding may be stably performed when the
welding bead BD is formed within an overlapped region, the welding
bead BD should be completely included in the overlapped region.
Accordingly, the welding position W1 should be a point spaced apart
by at least 0.5*W.sub.bead,min from OV.sub.min toward the inside of
the beading portion 21. Accordingly. W1 may satisfy the following
relation.
W .times. 1 = O .times. V min - 0.5 * W bead , min = R 1 , min + W
bead , min - 0.5 * W bead , min = R 1 , min + 0.5 * W bead , min
##EQU00001##
[0269] Because a PD value should be maximized in order to minimize
W1/PD, a minimum value of W/PD is
(OV.sub.min-0.5*W.sub.bead,min)/PD.sub.max.
[0270] In another aspect, referring to FIG. 11, a welding position
when the contact portion 33a is maximally placed on the beading
portion 21 may be defined as W2. An overlap length in this case is
OV.sub.max as described above. Because welding may be stably
performed when the welding bead is formed within an overlapped
region, the welding bead BD should be completely included in the
overlapped region. Accordingly, the welding position W2 should be a
point spaced apart by at least 0.5*W.sub.bead,min from OV.sub.max
toward the inside of the beading portion 21. Accordingly, W2 may
satisfy the following relation.
W .times. 2 = OV max - 0.5 * W bead , min = PD max - R 2 , min -
0.5 * W bead , min ##EQU00002##
[0271] In order maximize W2/PD,
{1-(R.sub.2,min+0.5*W.sub.bead,min)/PD} that is a value obtained by
dividing (PD.sub.max-R.sub.2,min-0.5*W.sub.bead,min) by PD should
be maximized. That is, when a PD value is maximized, a W2/PD value
is also maximized. Accordingly, a maximum value of W/PD is
(OV.sub.min-0.5*W.sub.bead,min)/PD.sub.max.
[0272] In an example, a minimum width required to weld the contact
portion 33a to the beading portion 21 may be 0.1 mm. That is, 0.1
mm corresponds to a minimum width of the welding bead BD that may
be formed by using laser welding. Accordingly, the welding position
W1 when the contact portion 33a minimally contacts a top surface of
the beading portion 21 corresponds to a point spaced apart by
(R.sub.1,min+0.5*0.1 mm) from an innermost point of the beading
portion 21. R.sub.1,min that is a minimum value of the radius of
curvature R1 is, for example, 0.05 mm. When a laser is irradiated
to the point, the welding bead BD having a width of 0.1 mm is
formed on a contact surface between the contact portion 33a and the
beading portion 21. A width of the welding bead BD corresponds to a
minimum contact width of the contact portion 33a. The welding
position W1 based on the press-fitting depth PD of the beading
portion 21 is a point spaced apart by 0.1 mm from the innermost
point of the beading portion 21.
[0273] When the contact portion 33a maximally contacts the top
surface of the beading portion 21, an end portion of the contact
portion 33a is located at a point spaced apart by a radius of
curvature from an inner surface of the battery housing. R.sub.2,min
that is a minimum value of the radius of curvature R2 is, for
example, 0.05 mm. In this case, the welding position W2 which may
be closest to an end of the contact portion 33a is a point spaced
apart by 0.05 mm from the end of the contact portion 33a. When a
laser is irradiated to the point, the welding bead having a minimum
width of 0.1 mm may be formed to contact the end of the contact
portion 33a. The welding position W2 when the contact portion 33a
maximally contacts the top surface of the beading portion 21 is a
point spaced apart by (PD-R.sub.2,min-0.05 mm) from the innermost
point of the beading portion 21. In an example, when R.sub.2,min is
0.05 mm, a maximum value of the welding position W2 is a point
spaced apart by PD-0.1 mm from the innermost point of the beading
portion 21.
[0274] As described above, when R.sub.1,min and R.sub.2,min are
each 0.05 mm, the welding position W of the contact portion 33a
based on the press-fitting depth PD may be set within a range of
(0.1 mm) to (PD-0.1 mm) based on the innermost point of the beading
portion 21. Because a ratio of the welding position W1 based on the
press-fitting depth PD is a value when the press-fitting depth PD
is maximized, a minimum value (%) of W1/PD is 1% (=100*0.1 mm/10
mm). Also, because a maximum value of W1/PD of the welding position
W2 based on the press-fitting depth PD is a value when the
press-fitting depth PD is maximized, a maximum value (%) of W2/PD
is 99% (=100*(10 mm-0.1 mm)/10 mm). For short, a welding position
region based on the press-fitting depth PD may be a region that is
equal to or greater than 1% and equal to or less than 99% based on
the press-fitting depth PD.
[0275] Referring to FIG. 11, a distance from an innermost point of
the beading portion 21 when the overlap length is OV to a central
point of the outermost welding bead BD in a radial direction may be
defined as W. In this case, the battery 1 may satisfy the following
relation.
W=OV-0.5*W.sub.bead,min
[0276] In another aspect, the beading portion 21 may include the
flat section F parallel to a bottom surface of the battery housing
20 in at least a region, and a length of the flat section F of the
beading portion 21 contacting the current collector 30 may be
OV-R1. That is, referring to FIG. 11, the flat section F
corresponds to a length obtained by subtracting the radius of
curvature R1 of the beading portion 21 from the overlap length
OV.
[0277] In another aspect of the present disclosure, when the
overlap length is OV, a radial width length of a welding pattern
which is a set of the welding beads BD formed between the beading
portion 21 and the contact portion 33a may be equal to or greater
than W.sub.bead,min and equal to or less than OV-R1.
[0278] Referring to FIG. 11, because a minimum width of the welding
bead BD is W.sub.bead,min, a minimum value of a radial width length
of the welding pattern which is formed between the beading portion
21 and the contact portion 33a should be at least W.sub.bead,min. A
plurality of welding beads BD may be formed over the entire flat
section F of the beading portion 21. In this case, the plurality of
welding beads BD may form a certain welding pattern. Referring to
FIG. 11, a maximum value of the radial width length of the welding
pattern which is formed between the beading portion 21 and the
contact portion 33a may satisfy the following relation.
Maximum .times. value .times. of .times. the .times. radial .times.
width .times. length .times. of .times. .times. the .times. welding
.times. which .times. is .times. formed .times. between .times. the
.times. beading .times. portion .times. 21 .times. and .times. the
.times. contact .times. portion .times. 33 .times. a = W - W
.times. 1 + minimum .times. width .times. of .times. the .times.
welding .times. bead .times. BD = [ ( O .times. V - 0.5 * W bead ,
min ) - ( R .times. 1 + 0.5 * W bead , min ) ] + W bead , min = OV
- R .times. 1 ##EQU00003##
[0279] In another aspect of the present disclosure, a ratio of the
radial width length of the welding pattern to a length of the flat
section F may range from about 10% to about 40%. Preferably, the
ratio may range from about 20% to about 30%. When the ratio
satisfies the range, welding strength may be increased as a welding
area is increased. Accordingly, the battery 1 according to the
present disclosure may secure high impact resistance.
[0280] In another aspect of the present disclosure, a ratio of the
area where the current collector 30 does not contact a top surface
of the electrode assembly 10 to the area of a circle having an
outer diameter of the electrode assembly 10 as a diameter may be
defined as an aperture ratio of the current collector 30. The
aperture ratio may be calculated as follows.
Aperture .times. ratio .times. ( % ) = 1 - ( area .times. where
.times. the .times. current .times. collector .times. contacts
.times. the .times. top .times. surface .times. of .times. the
.times. electrode .times. assembly ) / ( area .times. of .times.
the .times. circle .times. having .times. the .times. outer .times.
diameter .times. of .times. the .times. electrode .times. assembly
.times. as .times. the .times. diameter ) = ( area .times. where
.times. the .times. current .times. collector .times. does .times.
not .times. contact .times. the .times. top .times. surface .times.
of .times. the .times. electrode .times. assembly ) / ( area
.times. of .times. the .times. circle .times. having .times. the
.times. outer .times. diameter .times. of .times. the .times.
electrode .times. assembly .times. as .times. the .times. diameter
) ##EQU00004##
[0281] The aperture ratio of the current collector 30 may be, for
example, equal to or greater than about 30% and less than 10%, and
more particularly, may be equal to or greater than about 60% and
less than 100%. Assuming that the current collector 30 of FIG. 8a
is placed on and coupled to the electrode assembly 10, a region
where the current collector 30 contacts the electrode assembly 10
may be the central portion 31 and the tab coupling portion 32. That
is, a ratio of the area where the current collector 30 contacts the
electrode assembly 10 to the area of a circle having an outer
diameter of the electrode assembly 10 as a diameter may be equal to
or less than about 70%, and more particularly, may be equal to or
less than about 40%. When an aperture ratio of the current
collector 30 is within the range, an electrolytic solution may be
smoothly penetrated into the electrode assembly 10 through an
opening region of the current collector 30 having the current
collector hole H2 during injection of the electrolytic solution.
That is, when the aperture ratio of the current collector 30 is
within the range, the electrolytic solution may be penetrated into
the electrode assembly 10 through the opening region of the current
collector 30 and the winding central hole H1 formed in the
electrode assembly 10, and in particular, because there is a fine
gap between overlapped surfaces of the segments 11a and between
adjacent segments 11a, the electrolytic solution may be smoothly
penetrated into the electrode assembly 10 due to capillary action
through the gap.
[0282] Next, referring to FIG. 5, the current collector 30
according to another embodiment of the present disclosure is
illustrated. The current collector 30 according to another
embodiment of the present disclosure is only different in a shape
of the contact portion 33a from the current collector 30 of FIG.
4a, and thus, other structures of the current collector 30
described above may be substantially the same.
[0283] Referring to FIG. 5, at least a part of the contact portion
33a may extend along an inner circumferential surface of the
battery housing 20. For example, the contact portion 33a may have
an arc shape that extends along the beading portion of the battery
housing 20. Also, in order to maximize a contact area, the current
collector 30 may be configured so that a sum of an extending length
of the contact portion 33a of at least one housing coupling portion
33 is substantially the same as an inner circumference of the
battery housing 20. In this embodiment, a coupling area is
maximized, and thus, a coupling force may be improved and
electrical resistance may be reduced.
[0284] Next, referring to FIG. 6, the current collector 30
according to another embodiment of the present disclosure is
illustrated. The current collector 30 according to another
embodiment of the present disclosure is only different in shapes of
the contact portion 33a and the connecting portion 33b from the
current collector 30 of FIG. 5, and thus, other structures of the
current collector 30 described above may be substantially the
same.
[0285] Referring to FIG. 6, at least a part of the connecting
portion 33b may extend along an inner circumferential surface of
the battery housing 20. In detail, the contact portion 33a may have
an arc shape that extends along the beading portion of the battery
housing 20, and the connecting portion 33b may have an arc shape
that extends along the contact portion 33a. According to this
structure, because the area of the current collector 30 is
additionally increased when compared to the current collector 30 of
FIG. 5, the effect of reducing electrical resistance may be
maximized.
[0286] Referring to FIG. 6, the current collector 30 may not
include the bending portion B, unlike the current collector 30 of
FIGS. 4a and 5. When the current collector 30 does not include the
bending portion B, raw materials required to manufacture the
current collector 30 may be reduced. Accordingly, manufacturing
costs of the current collector 30 may be reduced.
[0287] Referring to FIG. 1a, the cap 40 covers the opening portion
formed on a side of the battery housing 20. The cap 40 may be fixed
by the crimping portion 22 formed on an upper end of the battery
housing 20. In this case, in order to improve a fixing force and
improve the sealing property of the battery housing 20, the sealing
gasket G1 may be located between the battery housing 20 and the cap
40. However, in the present disclosure, the cap 40 is not a
component that should function as a passage of current.
Accordingly, as long as the battery housing 20 and the cap 40 may
be firmly fixed and the sealing property of the opening portion of
the battery housing 20 may be secured through the application of
another structure well known in the related art, the application of
the sealing gasket G1 is not essential.
[0288] Assuming that the sealing gasket G1 is applied, the sealing
gasket G1 that is located between the opening portion of the
battery housing 20 and the current collector 30 may be configured
so that a portion of the current collector 30 contacting the
beading portion 21 is located between the beading portion 21 and
the sealing gasket G1. The sealing gasket G1 may have a
substantially annular shape surrounding the cap 40. The sealing
gasket G1 may simultaneously cover a top surface, a bottom surface,
and a side surface of the cap 40. A radial length of a portion of
the sealing gasket G1 covering the bottom surface of the cap 40 may
be equal to or less than a radial length of a portion of the
sealing gasket G1 covering the top surface of the cap 40. When a
radial length of a portion of the sealing gasket G1 covering the
bottom surface of the cap 40 is excessively large, the sealing
gasket G1 may press the current collector 30 in a process of
vertically compressing the battery housing 20 during a sizing
process, thereby damaging the current collector 30 or the battery
housing 20. In particular, when a radial length of a portion of the
sealing gasket G1 covering the bottom surface of the cap 40 is
excessively large, the sealing gasket G1 may excessively press the
connecting portion 33b in a process of vertically compressing the
battery housing 20 during a sizing process, thereby deforming the
connecting portion 33b or damaging a part of the connecting portion
33b. Accordingly, it is necessary to keep a radial length of a
portion of the sealing gasket G1 covering the bottom surface of the
cap 40 to a certain level.
[0289] In contrast, a portion of the sealing gasket G1 covering the
top surface of the cap 40 does not interfere with the current
collector 30 due to its structural and positional characteristics.
In another aspect, the battery housing 20 and the cap 40 do not
necessarily need to be insulated from each other. That is, because
a portion of the sealing gasket G1 covering the top surface of the
cap 40 needs only a sealing function and does not need insulation
or other separate functions, there are relatively few restrictions
on its length.
[0290] For example, as shown in FIG. 1a, a radial length of a
portion of the sealing gasket G1 covering the bottom surface of the
cap 40 may be the same as a radial length of a portion of the
sealing gasket G1 covering the top surface of the cap 40.
Alternatively, as shown in FIGS. 2 and 3, a radial length of a
portion of the sealing gasket G1 covering the bottom surface of the
cap 40 may be less than a radial length of a portion of the sealing
gasket G1 covering the top surface of the cap 40.
[0291] The contact portion 33a may be located and fixed between the
beading portion 21 of the battery housing 20 and the sealing gasket
G1. That is, the contact portion 33a may be fixed due to a crimping
force of the crimping portion 22 in a state where the contact
portion 33a is located between the beading portion 21 of the
battery housing 20 and the sealing gasket G1.
[0292] In this case, a thickness of the sealing gasket G1 may vary
according to a circumferential direction. For example, a thickness
of the sealing gasket G1 may be alternately increased and decreased
in the circumferential direction.
[0293] In an example, the sealing gasket G1 may have the same
compressibility in a region where the sealing gasket G1 contacts
the contact portion 33a and in a region where the sealing gasket G1
does not contact the contact portion 33a. That is, in an
uncompressed state, the sealing gasket G1 may be configured so that
a thickness of the sealing gasket G1 varies in the circumferential
direction.
[0294] In another example, the sealing gasket G1 may be configured
so that a compressibility in a region where the sealing gasket G1
does not contact the contact portion 33a is less than that in a
region where the sealing gasket G1 contacts the contact portion
33a. That is, in an uncompressed state, the sealing gasket G1 may
be configured to have a constant thickness in the circumferential
direction, and may be configured so that a thickness varies only in
a certain region when compressed due to a crimping force later.
[0295] In another example, the sealing gasket G1 may be configured
so that a thickness in a region where the sealing gasket G1 does
not contact the contact portion 33a is greater than that in a
region where the sealing gasket G1 contacts the contact portion
33a. That is the sealing gasket G1 may have a relatively high
compressibility in a region where the sealing gasket G1 contacts
the contact portion 33a.
[0296] In another aspect, a welding portion may be formed between
the beading portion 21 of the battery housing 20 and the contact
portion 33a of the current collector. For example, the fixing of
the contact portion 33a may not be reliable only with a crimping
force. In addition, when the sealing gasket G1 is contracted by
heat or the crimping portion 22 is deformed by external impact, a
coupling force between the current collector and the battery
housing 20 is likely to be reduced. Accordingly, the current
collector 30 may be fixed to the battery housing 20 through welding
in a state where the contact portion 33a is placed on the beading
portion 21 of the battery housing 20. Next, the cap 40 surrounded
by the sealing gasket G1 may be placed on an upper end of the
contact portion 33a and the crimping portion 22 may be formed, to
complete a manufacturing process of the battery 1. In this case,
examples of the welding method may include, but are not limited to,
laser welding, resistance welding, and ultrasonic welding. As such,
according to a structure in which the contact portion 33a is
located between the beading portion 21 and the sealing gasket G1
and the contact portion 33a is coupled to the beading portion 21
through welding, a coupling force of a welding portion may be
increased and surface adhesion may be ensured even with wobble for
a long time. Accordingly, safety problems such as cycle fading may
be minimized.
[0297] FIGS. 8a through 10 are views for describing a welding
region between the contact portion 33a and the beading portion
21.
[0298] Referring to FIGS. 8a through 10, the welding bead BD may be
formed in a welding region between the contact portion 33a and the
beading portion 21. For example, when a beading portion top surface
and a beading portion bottom surface are inclined at a certain
angle with respect to a bottom surface of the battery housing 20 as
shown in FIG. 1a, the contact portion 33a may be mounted on an
inclined top surface of the beading portion 21. Alternatively, as
shown in FIGS. 2 and 3, when each of the beading portion top
surface and the beading portion bottom surface includes the flat
section F parallel to the bottom surface of the battery housing 20
in at least a region, the contact portion 33a may be mounted on a
flat top surface of the beading portion 21. Next, the contact
portion 33a may be welded to the beading portion 21.
[0299] FIG. 11 is a view for describing a position, a length, and a
width of the welding bead BD formed in a welding region between the
contact portion 33a and the beading portion 21.
[0300] Referring to FIG. 11, the contact portion 33a may be welded
to a flat top surface of the beading portion 21.
[0301] Referring to 8a through 10, when a plurality of welding
beads BD may be gathered, a certain welding pattern may be formed.
For example, referring to FIG. 8a, a plurality of welding beads BD
may be gathered to form a welding pattern having a substantially
straight line shape. For example, a welding pattern formed between
the beading portion 21 and the contact portion 33a may have a
linear shape in which spot welding is connected. A width of the
welding bead BD formed between the beading portion 21 and the
contact portion 33a may be equal to or greater than about 0.1 mm.
This is because, when laser technology is considered, a minimum
width of the welding bead BD is equal to or greater than about 0.1
mm.
[0302] At least one welding bead BD may be formed between the
beading portion 21 and the contact portion 33a. For example, a
plurality of welding beads BD may be formed in a circumferential
direction between the beading portion 21 and the contact portion
33a. In particular, a plurality of welding beads BD formed between
the beading portion 21 and the contact portion 33a may be formed in
the same contact portion 33a. For example, the plurality of welding
beads BD formed in the same contact portion 33a may be
symmetrically formed in the same contact portion 33a. The plurality
of welding beads BD formed in the same contact portion 33a may be
formed at an interval of a certain angle, for example, 30.degree..
In detail, the plurality of welding beads BD formed in the same
contact portion 33a may be located within a circumferential angle
range of 30.degree. or less based on the center of a circle formed
by the beading portion 21 in the same contact portion 33a.
[0303] The welding beads BD formed between the beading portion 21
and the contact portion 33a may form a welding pattern having a
straight line shape extending in the circumferential direction.
Alternatively, the welding beads BD formed between the beading
portion 21 and the contact portion 33a may form a welding pattern
having an arc shape extending in the circumferential direction.
According to an embodiment of the present disclosure, a
circumferential length of the contact portion 33a may be the same
as a circumferential length of the tab coupling portion 32. Also, a
circumferential length of the contact portion 33a may be the same
as a circumferential length of the connecting portion 33b. For
example, as shown in FIG. 4a, the tab coupling portion 32, the
connecting portion 33b, and the contact portion 33a may extend to
have the same width.
[0304] In another aspect, an extension direction of a welding
pattern formed between the first uncoated portion 11 and the tab
coupling portion 32 and an extension direction of a welding pattern
formed between the beading portion 21 and the contact portion 33a
may be different from each other. Preferably, an extension
direction of a welding pattern formed between the first uncoated
portion 11 and the tab coupling portion 32 and an extension
direction of a welding pattern formed between the beading portion
21 and the contact portion 33a may be substantially perpendicular
to each other. Referring to FIGS. 8a and 8b, a welding pattern
formed between the first uncoated portion 11 and the tab coupling
portion 32 may be formed in a radial direction. A welding pattern
formed between the beading portion 21 and the contact portion 33a
may be formed in a circumferential direction of the battery housing
20. That is, an extension direction of the welding pattern formed
between the first uncoated portion 11 and the tab coupling portion
32 and an extension direction of the welding pattern formed between
the beading portion 21 and the contact portion 33a may be
substantially perpendicular to each other. According to this
structure, coupling strength between the current collector 30 and
the electrode assembly 10 may be increased. That is, according to
this structure, because the current collector 30 is fixed by
welding performed in various directions, even when the current
collector 30 receives vibration or impact in a specific direction,
the current collector 30 may be firmly fixed.
[0305] According to another embodiment of the present disclosure, a
circumferential length of the contact portion 33a may be greater
than a circumferential length of the tab coupling portion 32. Also,
preferably, a circumferential length of the contact portion 33a may
be greater than a circumferential length of the connecting portion
33b. For example, referring to FIGS. 5 and 6, it may be found that
a circumferential length of the contact portion 33a is greater than
a circumferential length of the tab coupling portion 32. Also,
referring to FIG. 5, it may be found that a circumferential length
of the contact portion 33a is greater than a circumferential length
of the connecting portion 33b. As such, when a circumferential
length of the contact portion 33a is large, a coupling force
between the beading portion 21 and the current collector 30 may be
improved. Furthermore, when a circumferential length of the contact
portion 33a and/or the connecting portion 33b is large, the
internal resistance of a battery may be reduced.
[0306] Referring to FIGS. 5 and 6, the contact portion 33a may have
an arc shape extending in a circumferential direction along the
beading portion 21 of the battery housing. In more detail, the
contact portion 33a may have an arc shape extending in opposite
directions along the circumferential direction, from an
intersection between the connecting portion 33b and the contact
portion 33a.
[0307] Referring to FIG. 6, the connecting portion 33b may have an
arc shape extending in the circumferential direction along the
contact portion 33a. Because the contact portion 33a has an arc
shape extending in the circumferential direction along the beading
portion 21 of the battery housing, a coupling force between the
beading portion 21 and the current collector may be improved. More
preferably, a sum of lengths of the contact portions 33a extending
in the circumferential direction may correspond to a length of an
inner circumference of the battery housing. That is, the current
collector 30 may have an annular shape in which the contact
portions 33a are connected to one another. According to this shape,
a coupling force between the beading portion 21 and the current
collector 30 may be further improved.
[0308] FIG. 12 is a view for describing a relationship between a
diameter of an inner surface of a battery housing and a total
diameter of a current collector.
[0309] Referring to FIG. 12, when a diameter of an outer surface of
the battery housing is De, a diameter of an inner surface of the
battery housing 20 is Di, and a total diameter of the current
collector 30 is d, a relationship of De>Di>d may be
satisfied.
[0310] The cap 40 may include a venting portion 41 formed to
prevent an increase in internal pressure due to gas generated
inside the battery housing 20. The venting portion 41 is formed in
a part of the cap 40, and corresponds to a region that is
structurally weaker than a peripheral region to be easily ruptured
when internal pressure is applied. The venting portion 41 may be a
region having a smaller thickness than the peripheral region.
[0311] The terminal 50 passes through the battery housing 20 from
the opposite side to the opening portion of the battery housing 20
and is electrically connected to the second uncoated portion 12 of
the electrode assembly 10. The terminal 50 may pass through a
substantially central portion of a bottom surface of the battery
housing 20. The terminal 50 may be coupled to the current collector
(second current collector) P coupled to the second uncoated portion
12 or may be coupled to a lead tab coupled to the second uncoated
portion 12, to be electrically connected to the electrode assembly
10. Accordingly, the terminal 50 may have the same polarity as a
second electrode of the electrode assembly 10, and may function as
a second electrode terminal T2. When the second uncoated portion 12
is a positive electrode tab, the terminal 50 may function as a
positive electrode terminal. Preferably, the terminal 50 has a
riveted structure. A battery to which a riveting structure of the
terminal 50 is applied may perform electrical wiring in one
direction. Also, because the terminal 50 having the riveting
structure has a large cross-sectional area and thus has low
resistance, the terminal 50 is very suitable for rapid
charging.
[0312] FIGS. 18a and 18b are views for describing the second
current collector P, according to an embodiment of the present
disclosure.
[0313] In another aspect of the present disclosure, referring to
FIGS. 2 and 3, the second current collector P may be located
between the second uncoated portion 12 and the terminal 50.
Referring to FIGS. 18a and 18b, the second current collector P
includes: a tab coupling portion P1 coupled to the second uncoated
portion 12; and a terminal coupling portion P2 coupled to the
terminal 50. The second current collector P may further include a
connecting portion P3 and/or an edge portion P4.
[0314] In an aspect of the present disclosure, a plurality of tab
coupling portions P1 may be provided. Preferably, the plurality of
tab coupling portions P1 may be arranged at the same interval.
Extending lengths of the plurality of tab coupling portions P1 may
be the same. The terminal coupling portion P2 may be surrounded by
the plurality of tab coupling portions P1.
[0315] Preferably, the terminal coupling portion P2 may be located
at a position corresponding to the winding central hole H1 formed
at a winding center of the electrode assembly 10. More preferably,
the terminal coupling portion P2 may cover the winding central hole
H1 of the electrode assembly 10. According to this structure, the
terminal 50 and the terminal coupling portion P2 located over the
winding central hole H1 of the electrode assembly 10 may be
welded.
[0316] The tab coupling portion P1 and the terminal coupling
portion P2 may be spaced apart from each other without being
directly connected to each other. For example, the tab coupling
portion P1 and the terminal coupling portion P2 may be indirectly
connected by the edge portion P4. As such, in the second current
collector P according to an embodiment of the present disclosure,
because the tab coupling portion P1 and the terminal coupling
portion P2 are connected through the edge portion P4 without being
directly connected to each other, when impact and/or vibration
occurs in the battery 1, impact applied to a coupling portion
between the tab coupling portion P1 and the second uncoated portion
12 and a coupling portion between the terminal coupling portion P2
and the terminal 50 may be distributed. Accordingly, the second
current collector P may minimize or prevent damage to a welding
portion due to external impact. The second current collector P of
the present disclosure has a structure in which stress may be
concentrated on a connected portion between the edge portion P4 and
the terminal coupling portion P2 when external impact is applied.
Because the connected portion is not a region where a welding
portion for coupling components is formed, product defects due to
damage to the welding portion caused by external impact may be
prevented.
[0317] The second current collector P may further include the
connecting portion P3 connected to the terminal coupling portion
P2. The connecting portion P3 may be narrower than the tab coupling
portion P1. In this case, electrical resistance in the connecting
portion P3 is increased and larger resistance is generated than in
another portion when current flows through the connecting portion
P3, and thus, when overcurrent occurs, a part of the connecting
portion P3 is broken, thereby blocking the overcurrent. A width of
the connecting portion P3 may be adjusted to an appropriate level
by considering an overcurrent blocking function.
[0318] The second current collector P may further include the edge
portion P4 having a substantially rim shape in which an empty space
is formed. In this case, the tab coupling portion P1 may extend
inward from the edge portion P4, and may be coupled to the second
uncoated portion 12. Although the edge portion P4 has a
substantially circular rim shape in FIG. 18a, the present
disclosure is not limited thereto. The edge portion P4 may have a
substantially quadrangular rim shape or another shape, unlike in
FIG. 18a.
[0319] In another aspect of the present disclosure, referring to
FIG. 18b, the connecting portion P3 may include a notch portion N
formed to partially reduce a width of the connecting portion P3.
When the notch portion N is provided, electrical resistance in a
region where the notch portion N is formed is increased, and thus,
when overcurrent occurs, the overcurrent may be rapidly blocked.
Preferably, a position of the notch portion N may be included in a
stack number uniform section (FIG. 1d). More preferably, a position
of the notch portion N may be included in a portion of the stack
number uniform section in which the number of overlapping layers is
maintained at a maximum. Accordingly, a byproduct generated when
the notch portion N is broken may be reliably prevented from being
penetrated into the electrode assembly.
[0320] Referring to FIGS. 2 and 3 together with FIGS. 18a and 18b,
in an aspect of the present disclosure, a longest radius from the
center of the terminal coupling portion P2 of the second current
collector P to an end of the tab coupling portion P1 may be greater
than a longest radius from a central portion of the current
collector 30 to an end of the tab coupling portion 32. For example,
a radius of the edge portion P4 having a substantially rim shape
may be greater than a longest radius from a central portion of the
current collector 30 to an end of the tab coupling portion 32. This
is because, when the beading portion 21 is press-fitted into the
battery housing 20, a welding area between the tab coupling portion
32 of the current collector 30 and the first uncoated portion 11 is
limited.
[0321] In another aspect of the present disclosure, the tab
coupling portion P1 of the second current collector P may be
coupled to a bent end portion of the second uncoated portion 12.
That is, the tab coupling portion P1 of the second current
collector P may be welded to a bent surface formed by a plurality
of segments of the second uncoated portion 12. Preferably, a
welding region may overlap a stack number uniform section (FIG. 1d)
by at least 50% in a radial direction, and the larger the overlap
ratio, the more preferable. More preferably, a welding region may
overlap a portion of the stack number uniform section in which the
number of overlapping layers is at a maximum in the radial
direction by at least 50%, and the larger the overlap ratio, the
more preferable. Substantially the same conditions as these welding
conditions may be applied to the current collector 30.
[0322] In another aspect of the present disclosure, a welding
region for coupling the tab coupling portion P1 of the second
current collector P to the bent end portion of the second uncoated
portion 12 may be further formed, and a distance from the center of
the terminal coupling portion P2 of the second current collector P
to the welding region may be the same as or may have a distance
deviation of about 5% or less from a distance from a central
portion of the current collector 30 to a welding region on the tab
coupling portion 32. In another aspect of the present disclosure,
the welding region of the second current collector P may have a
length greater than that of the welding region on the tab coupling
portion 32 of the current collector 30.
[0323] In an example, a flat portion (see FIG. 1a) of the terminal
50 and the second current collector P are welded by a laser and are
welded in a continuous or discontinuous line to have an arc
pattern, a diameter of the arc welding pattern may be equal to or
greater than 2 mm, and more particularly may be equal to or greater
than 4 mm. When the diameter of the arc welding pattern satisfies
the condition, a tensile force of a welding portion may be
increased to 2 kgf or more and thus sufficient welding strength may
be secured.
[0324] In another example, when the flat portion of the terminal 50
and the second current collector P are welded by ultrasound and are
welded in a circular pattern, it is preferable that a diameter of
the circular welding pattern is equal to or greater than 2 mm. When
the diameter of the circular welding pattern satisfies the
condition, a tensile force of a welding portion may be increased to
2 kgf or more and thus sufficient welding strength may be
secured.
[0325] A diameter of the flat portion of the terminal 50
corresponding to a weldable region may be adjusted in a range of 3
mm to 14 mm. When a radius of the flat portion of the terminal 50
is less than 3 mm, it is difficult to form a welding pattern having
a diameter of 2 mm or more by using a laser welding tool, an
ultrasonic welding tool, or the like. Also, when a radius of the
flat portion of the terminal 50 exceeds 14 mm, a size of the
terminal 50 may be excessively increased and the area occupied by
an outer surface of the bottom of the battery housing 20 may be
reduced, and thus, it is difficult to connect an electrical
connection component (bus bar) through the outer surface.
[0326] Preferably, because a diameter of a welding pattern is equal
to or greater than 2 mm and a diameter of a weldable region ranges
from 3 mm to 14 mm to secure a tensile force of a welding portion
of 2 kgf or more, a ratio of the area of the welding pattern to the
area of the weldable region may range from 2.04
(100*.pi.1.sup.2/.pi.7.sup.2)% to 44.4
(100*.pi.1.sup.2/.pi.1.5.sup.2)%.
[0327] When the polarity and function of the terminal 50 are
considered, the terminal 50 should maintain an insulated state from
the battery housing 20 having the opposite polarity. To this end,
the insulating gasket G2 may be applied between the terminal 50 and
the battery housing 20. Alternatively, insulation may be achieved
by coating an insulating material on a part of a surface of the
terminal 50.
[0328] For the same reason, the second uncoated portion 12 and/or
the current collector (second current collector) P should maintain
an insulated state from the battery housing 20. To this end, the
insulator S may be located between the second uncoated portion 12
and the battery housing 20 and/or between the current collector
(second current collector) P and the battery housing 20. When the
insulator S is applied, the terminal 50 may pass through the
insulator S for electrical connection with the second uncoated
portion 12.
[0329] Preferably, the insulator S and an inner surface of the
bottom of the battery housing 20 may be in close contact with each
other. `Close contact` means that there is no space (gap)
identified visually. In order to remove a space (gap), a distance
from the inner surface of the bottom of the battery housing 20 to
the flat portion of the terminal 50 may be equal to or slightly
less than a thickness of the insulator S.
[0330] In the present disclosure, the entire surface of the battery
housing 20 may function as a first electrode terminal T1. For
example, when the first uncoated portion 11 is a negative electrode
tab, the first electrode terminal T1 may be a negative electrode
terminal. The battery 1 according to the present disclosure has a
structure in which the terminal 50 exposed on a bottom surface of
the battery housing 20 located opposite to an opening portion and a
portion of the bottom surface of the battery housing 20 other than
a portion occupied by the terminal 50 may be respectively used as
the second electrode terminal T2 and the first electrode terminal
T1. Accordingly, in the battery 1 according to the present
disclosure, when a plurality of batteries 1 are electrically
connected, both a positive electrode and a negative electrode may
be connected, thereby simplifying an electrical connection
structure. Also, because the battery 1 has a structure in which
most of a bottom surface of the battery housing 20 located opposite
to an opening portion may be used as an electrode terminal, a
sufficient area for welding components for electrical connection
may be secured.
[0331] In another aspect, an electrode of the electrode assembly 10
may have a segmentation structure for ease of bending the uncoated
portion 11.
[0332] Referring to FIG. 14, an electrode plate includes a first
electrode current collector having a sheet shape and formed of a
conductive foil, an active material layer formed on at least one
surface of the first electrode current collector, and the first
uncoated portion 11 in which an active material is not coated on a
long side end of a first electrode.
[0333] Preferably, the first uncoated portion 11 may include a
plurality of segments 11a that are notched. The plurality of
segments 11a may be divided into a plurality of groups, and the
segments 11a included in each group may have the same height
(length in a Y direction) and/or the same width (length in an X
direction) and/or the same separation pitch. The number of segments
11a included in each group may be more or less than that
illustrated. The segment 11a has a geometric shape in which at
least one straight line and/or at least one curved line are
combined. Preferably, the segment 11a may have a trapezoidal shape,
but may be modified into any of shapes such as a quadrangular
shape, a parallelogram shape, a semicircular shape, or a
semi-elliptical shape.
[0334] Preferably, a height of the segment 11a may be increased
stepwise in one direction parallel to a winding direction of the
electrode assembly, for example, from a core side to an outer
circumference side. Also, a core side-uncoated portion 11' adjacent
to the core side may not include the segment 11a, and a height of
the core-side uncoated portion 11' may be less than that of other
uncoated regions. Also, an outer circumference-side uncoated
portion 11'' adjacent to the outer circumference side may not
include the segment 11a, and a height of the outer
circumference-side uncoated portion 11'' may be less than that of
other uncoated regions.
[0335] Optionally, an electrode plate may include an insulating
coating layer 11b covering a boundary between the active material
layer and the first uncoated portion 11. The insulating coating
layer 11b may include an insulating polymer resin, and may
optionally further include an inorganic filler. The insulating
coating layer 11b may prevent an end portion of the active material
layer from contacting a facing active material layer having the
opposite polarity through a separator, and may structurally support
bending of the segment 11a. To this end, when the electrode plate
is wound for the electrode assembly 10, it is preferable that at
least a part of the insulating coating layer 11b is exposed to the
outside from the separator.
[0336] FIG. 15 is a cross-sectional view illustrating the electrode
assembly 10, in which an uncoated portion segmentation structure of
an electrode plate is applied to a first electrode current
collector and a second electrode current collector, taken along a
longitudinal direction Y, according to an embodiment of the present
disclosure.
[0337] Referring to FIG. 15, the electrode assembly 10 may be
manufactured by using a winding method. The second uncoated portion
12 protruding downward extends from the second electrode current
collector, and the first uncoated portion 11 protruding upward
extends from the first electrode current collector.
[0338] A pattern in which heights of the first and second uncoated
portions 11, 12 are changed is schematically illustrated. That is,
heights of the uncoated portions 11, 12 may be irregularly changed
according to cut positions. For example, when a side portion of the
segment 11a having a trapezoidal shape is cut, a height of an
uncoated portion in a cross-section is less than a height of the
segment 11a. Accordingly, it should be understood that heights of
the uncoated portions 11, 12 shown in a cross-sectional view of the
electrode assembly 10 correspond to an average of uncoated portion
heights included in each winding turn.
[0339] As shown in FIGS. 16a and 16b, the uncoated portions 11, 12
may be bent in a radial direction of the electrode assembly 10, for
example, from an outer circumference side to a core side. In FIG.
15, a bent portion 101 is marked by a dashed line box. When the
uncoated portions 11, 12 are bent, the segments Ila adjacent to one
another in the radial direction overlap one another in multiple
layers to form the bent surfaces 102 over and under the electrode
assembly 10. In this case, the core-side uncoated portion 11' (see
FIG. 14) has a low thickness and thus is not bent, and a height h
of the segment 11a that is a bent innermost segment is equal to or
less than a radial length r of a winding region formed by the
core-side uncoated portion 11' with no segment structure.
Accordingly, the winding central hole H1 at the core of the
electrode assembly 10 is not closed by the bent segments 11a. When
the winding central hole H1 is not closed, there is no difficulty
in an electrolyte injection process, and electrolyte injection
efficiency is improved. Also, the terminal 50 and the second
current collector P may be easily welded by inserting a welding
tool through the winding central hole H1.
[0340] FIG. 17 is a view illustrating a state where the batteries 1
are electrically connected by using a bus bar 150, according to an
embodiment of the present disclosure.
[0341] Referring to FIG. 17, the plurality of batteries 1 may be
connected in series and in parallel in an upper portion by using
the bus bar 150. The number of batteries 1 may be increased or
decreased by considering the capacity of a battery pack 3.
[0342] In each battery 1, the terminal 50 may have a positive
polarity and an outer surface of the bottom of the battery housing
20 may have a negative polarity, or vice versa.
[0343] Preferably, the plurality of batteries 1 may be arranged in
a plurality of columns and rows. Columns are provided in a vertical
direction based on the FIG. 17, and rows are provided in a left and
right direction based on the FIG. 17. Also, in order to maximize
space efficiency, the batteries 1 may be arranged in a closest
packing structure. The closest packing structure is formed when a
regular triangle is formed by connecting the centers of the
terminals 50.
[0344] Preferably, the bus bar 150 may be located on adjacent
batteries 1, and preferably, between the terminals 50. In an
example, the bus bar 150 may be located between adjacent columns.
Alternatively, the bus bar 150 may be located between adjacent
rows.
[0345] Preferably, the bus bar 150 connects batteries arranged in
the same column in parallel, and connects batteries arranged in two
adjacent columns in series.
[0346] Preferably, the bus bar 150 may include a body portion 151,
a plurality of first bus bar terminals 152, and a plurality of
second bus bar terminals 153 for serial and parallel
connection.
[0347] The body portion 151 may extend along a column of the
batteries 1. Alternatively, the body portion 151 may extend along a
column of the batteries 1, and may be regularly bent like a zigzag
shape.
[0348] The plurality of first bus bar terminals 152 may protrude
from a side of the body portion 151 to the terminal 50 of each
battery 1, and may be electrically coupled to the terminal 50. The
electrical connection with the terminal 50 may be performed by
using laser welding, ultrasonic welding, or the like. Also, the
plurality of second bus bar terminals 153 may protrude from the
other side of the body portion 151 to the outer surface of the
bottom of the battery housing 20 of each battery 1, and may be
electrically coupled to the outer surface. The electrical
connection with the outer surface may be performed by using laser
welding, ultrasonic welding, or the like.
[0349] Preferably, the body portion 151, the plurality of first bus
bar terminals 152, and the plurality of second bus bar terminals
153 may be formed of one conductive metal plate. The metal plate
may be, but is not limited to, an aluminum plate or a copper plate.
In a modified example, the body portion 151, the plurality of first
bus bar terminals 152, and the plurality of second bus bar
terminals 153 may be manufactured as separate pieces and then may
be coupled to one another through welding or the like.
[0350] In the battery 1, because the terminal 50 having a positive
polarity and the outer surface of the bottom of the battery housing
20 having a negative polarity are located in the same direction,
the batteries 1 may be easily electrically connected by using the
bus bar 150.
[0351] Also, because the terminal 50 of the battery 1 and the outer
surface have large areas, a sufficient coupling area of the bus bar
150 may be secured and the resistance of the battery pack including
the battery 1 may be sufficiently reduced.
[0352] As described above, the battery 1 of the present disclosure
has a structure in which resistance is minimized by increasing a
contact area between components, multiplexing a current path,
minimizing a current path length, and the like. After a product is
finally manufactured, AC resistance of the battery 1 measured by
using a resistance measuring instrument between a positive
electrode and a negative electrode, that is, between a top surface
of the terminal 50 and an outer surface of a closed portion of the
battery housing 20, may be equal to or less than about 4 mohm, but
greater than 0 mohm, such as 0.01 mohm.
[0353] In the present disclosure, a battery may be, for example, a
battery in which a form factor ratio (defined as a value obtained
by dividing a diameter of the battery by a height, that is, a ratio
between a height H and a diameter D) is greater than about 0.4.
[0354] The term "form factor" used herein refers to a value
indicating a diameter and a height of a battery. The battery
according to an embodiment of the present disclosure may be, for
example, a 46110 battery, a 4875 battery, a 48110 battery, a 4880
battery, or a 4680 battery. In the numerical value indicating the
form factor, first two numbers indicate a diameter of a battery,
next two numbers indicate a height of the battery.
[0355] When a battery has recently been applied to an electric
vehicle, a form factor of a battery has increased to be larger than
1865, 2170, or the like. The increase in the form factor leads to
increased energy density, enhanced safety against thermal runaway,
and improved cooling efficiency.
[0356] The energy density of a battery may be further increased
when an unnecessary space inside a battery housing is minimized
along with the increase of the form factor. A battery according to
the present disclosure has an optimal structure in which a coupling
force of a coupling portion between a current collector and a
battery housing may be improved, the capacity of a battery may be
increased, and resistance may be reduced.
[0357] A battery according to an embodiment of the present
disclosure may be a battery having a substantially cylindrical
shape, whose diameter is about 46 mm, height is about 110 mm, and
form factor ratio is about 0.418.
[0358] A battery according to another embodiment may be a battery
having a substantially cylindrical shape, whose diameter is about
48 mm, height is about 75 mm, and form factor ratio is about
0.640.
[0359] A battery according to another embodiment may be a battery
having a substantially cylindrical shape, whose diameter is about
48 mm, height is about 110 mm, and form factor ratio is about
0.436.
[0360] A battery according to another embodiment may be a battery
having a substantially cylindrical shape, whose diameter is about
48 mm, height is about 80 mm, and form factor ratio is about
0.600.
[0361] A battery according to another embodiment may be a battery
having a substantially cylindrical shape, whose diameter is about
46 mm, height is about 80 mm, and form factor ratio is about
0.575.
[0362] In the related art, batteries having a form factor ratio of
about 0.4 or less have been used. That is, in the related art, for
example, a 1865 battery, a 2170 battery, etc. have been used. The
1865 battery has a diameter of about 18 mm, a height of about 65
mm, and a form factor ratio of about 0.277. The 2170 battery has a
diameter of about 21 mm, a height of about 70 mm, and a form factor
ratio of about 0.300.
[0363] A battery according to an embodiment of the present
disclosure may be included in a battery pack, and the battery pack
may be mounted in a vehicle. Referring to FIG. 19, a battery pack 3
according to an embodiment of the present disclosure includes a
battery assembly in which the plurality of batteries 1 according to
an embodiment of the present disclosure are electrically connected,
and a pack housing 2 in which the battery assembly is accommodated.
In FIG. 19 of the present disclosure, for convenience of
explanation, components for electrical connection such as a bus
bar, a cooling unit, and a power terminal are not shown.
[0364] Referring to FIG. 20, a vehicle 5 according to an embodiment
of the present disclosure may be, for example, an electric vehicle,
a hybrid vehicle, or a plug-in hybrid vehicle, and includes the
battery pack 3 according to an embodiment of the present
disclosure. The vehicle 5 operates by receiving power from the
battery pack 3 according to an embodiment of the present
disclosure.
[0365] Although the embodiments of the present disclosure have been
illustrated and described above, the present disclosure is not
limited to the above-described specific embodiments. Various
modified embodiments may be made by one of ordinary skill in the
art without departing from the scope of the present disclosure as
claimed in the claims.
* * * * *