U.S. patent application number 15/716910 was filed with the patent office on 2018-01-18 for battery and production method thereof.
This patent application is currently assigned to Kabushiki Kaisha Toshiba. The applicant listed for this patent is Kabushiki Kaisha Toshiba. Invention is credited to Eiki KASHIWAZAKI, Kengo KURATA, Toshifumi SHIMIZU, Natsuki TOYOTA.
Application Number | 20180019448 15/716910 |
Document ID | / |
Family ID | 44482953 |
Filed Date | 2018-01-18 |
United States Patent
Application |
20180019448 |
Kind Code |
A1 |
SHIMIZU; Toshifumi ; et
al. |
January 18, 2018 |
BATTERY AND PRODUCTION METHOD THEREOF
Abstract
According to one embodiment, there is provided a battery having
a plurality of current collector tabs extended from a plurality of
points of a current collector of at least one electrode of a
positive electrode and a negative electrode. The battery further
has a lid and a lead. The lead has a current collector tab
junctional part connected with the current collector tabs, a lid
junctional part fixed to the lid, and a vibration absorber part
linking the current collector tab junctional part to the lid
junctional part.
Inventors: |
SHIMIZU; Toshifumi;
(Saku-shi, JP) ; KURATA; Kengo; (Saku-shi, JP)
; TOYOTA; Natsuki; (Kashiwazaki-shi, JP) ;
KASHIWAZAKI; Eiki; (Annaka-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kabushiki Kaisha Toshiba |
Minato-ku |
|
JP |
|
|
Assignee: |
Kabushiki Kaisha Toshiba
Minato-ku
JP
|
Family ID: |
44482953 |
Appl. No.: |
15/716910 |
Filed: |
September 27, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14313681 |
Jun 24, 2014 |
9812675 |
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15716910 |
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13588121 |
Aug 17, 2012 |
9023501 |
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14313681 |
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PCT/JP11/53244 |
Feb 16, 2011 |
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13588121 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01M 2/024 20130101;
H01M 2/12 20130101; H01M 2/263 20130101; B23K 26/20 20130101; H01M
2/26 20130101; H01M 2/22 20130101; H01M 2/0217 20130101; B23K 26/00
20130101; Y10T 29/4911 20150115; H01M 2/0426 20130101 |
International
Class: |
H01M 2/02 20060101
H01M002/02; H01M 2/26 20060101 H01M002/26; H01M 2/04 20060101
H01M002/04; B23K 26/20 20140101 B23K026/20; B23K 26/00 20140101
B23K026/00; H01M 2/22 20060101 H01M002/22 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 17, 2010 |
JP |
2010-032952 |
Mar 15, 2010 |
JP |
2010-058181 |
Claims
1. A production method of an angular battery comprising an angular
tube-shaped metal container having a bottom; a positive electrode
and a negative electrode accommodated in the container; a lid
placed on an opening part of the container; and a terminal fixed to
the lid by caulking and connected to the positive electrode or the
negative electrode electrically, wherein the lid comprises a bottom
placed in the opening part of the container, and a stair part
located above the bottom and protruding outward beyond the bottom,
the method comprising: placing the bottom of the lid in the opening
part of the container accommodating the positive electrode and the
negative electrode, and placing the stair part of the lid on an
upper end of a side wall of the container; and irradiating a laser
from a direction vertical to a surface at which the stair part of
the lid is overlaid on the upper end of a side wall of the
container to weld the stair part of the lid to the upper end of a
side wall of the container by laser welding.
2. The method according to claim 1, wherein the stair part of the
lid has a thickness being the same as or less than a wall thickness
of the container.
3. The method according to claim 1, wherein the lid comprises a
through hole in which the terminal is fixed by caulking, and a
depression at a part corresponding to the through hole on sides in
a long side direction of the lid.
4. An angular battery produced by the method according to claim 1.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of and claims priority
under 35 U.S.C. .sctn.120 from U.S. application Ser. No. 14/313,681
filed Jun. 24, 2014, which is a division of U.S. application Ser.
No. 13/588,121 filed Aug. 17, 2012 (now U.S. Pat. No. 9,023,501
issued May 5, 2015), which is a continuation of PCT Application No.
PCT/JP2011/053244 filed Feb. 16, 2011, and claims the benefit of
priority under 35 U.S.C. .sctn.119 from Japanese Patent
Applications Nos. 2010-032952 filed Feb. 17, 2010 and 2010-058181
filed Mar. 15, 2010, the entire contents of each of which are
incorporated herein by reference.
FIELD
[0002] Embodiments described herein relate generally to a battery
and a production method thereof.
BACKGROUND
[0003] Lithium secondary battery has recently been developed as a
nonaqueous electrolyte secondary battery which is small and light,
has a high energy density, and is capable of repeated discharge and
charge, with the development of electronic devices. Lately, it has
also been desired to develop a nonaqueous electrolyte secondary
battery capable of fast charge and high output discharge, which is
suitable as a secondary battery for cars such as a hybrid car and
an electric car, or as a secondary battery for electric current
storage which is used for electricity equalization.
[0004] It is necessary to take out electric current efficiently in
order to improve a fast charge performance and a high output
discharge performance of a nonaqueous electrolyte secondary
battery. For this aim, it is desirable to derive current collector
tabs from multiple points of an electrode. These current collection
tabs are electrically connected to external terminals equipped on a
lid through a lead. The lid further has a safety valve for
releasing the pressure.
[0005] In one aspect, for example, in a case where a nonaqueous
electrolyte secondary battery is loaded in an electric car, when a
vibration or impact is applied to the battery from the outside,
vibration of an electrode in the battery may be transmitted to a
lid through a current collection tab and a lead, whereby a safety
valve may be broken. In particular, in a case of a large-sized
nonaqueous electrolyte secondary battery for a car, the electrode
is also large, which increases the influence of vibration. For this
reason, the risk of damage to a safety valve becomes large due the
transmission of vibration.
[0006] JP-A No. 2002-279962 discloses a positive electrode current
collector plate 82 in which an accordion-pressed plate 84 is linked
to a fitting hole 91 for fitting a positive electrode terminal
through a narrow section 92. The accordion-pressed plate 84 has
folded parts 85A, 85B and 85C, and several laminated positive
electrodes 87 are inserted into each folded parts. The narrow
section 92 forms a current collecting path (see FIG. 13). In the
positive electrode current collector 82 in JP-A No. 2002-279962,
however, the transmission of vibration of the electrode to a
positive electrode terminal cannot be inhibited, because the plate
84 and the fitting hole 91 are located on almost the same plane
surface.
[0007] JP-A No. 2003-346771 discloses a current collecting
connector 2 comprising a body 2a having an almost trapezoidal form
and placed horizontally at ends of two power generation elements
lined up. The current collecting connector 2 further comprises four
electrode connecting parts 2b having long and narrow form and
protruding downward from the body 2a. However, a large space is
necessary for setting of the current collecting connector 2 in JP-A
No. 2003-346771, because the electrode connecting parts 2b reach
the lower end of an electrode from the body, and an energy density
of a battery is reduced.
[0008] In another aspect, a problem occurs in which a welding yield
is lowered depending on the method used for fixing a lid to a
container. For example, if positions at which lid is fixed are not
constant, not only battery sizes but also heights of electrode
terminals attached to the lids vary. If the height of the electrode
terminal is different from others in the single batteries, welding
defects easily occur when an assembled battery is produced by
welding the electrode terminals of the single batteries to
electrically connect them. As a result, a welding yield is reduced.
In addition, when an electrode terminal is fixed to a lid by
caulking, the lid may be deformed by the caulking. When the lid is
deformed, the degree of fitting between the lid and a case is
degraded, and a gap is easily generated between the lid and the
case. As a result, a welding yield is reduced in a welded part
between the lid and the case.
[0009] A method for producing an angular sealed battery of JP-A No.
9-7557 is generally used for an alkali secondary battery such as a
nickel-hydrogen secondary battery. According to JP-A No. 9-7557,
when a fitted part between an opening end of a container and a lid
plate is laser welded to seal the fitted part, a lid plate having a
taper peripheral edge is used.
[0010] In a sealed battery in JP-A No. 10-144268, an inner
peripheral edge of an opening part of a container is formed as a
hole side taper, which is opened out, to receive a lid, and an
outer periphery of the lid is formed as an axis side taper to fit
in the taper of the opening part. Both tapers are formed so that
the welding for joining the lid and the container can be performed
from a direction toward a top surface of the lid, when the lid is
fitted in the opening part of the container. According to JP-A No.
10-144268, the joined part between the lid and the container is
welded from a direction toward the top surface of the lid in the
state in which the lid is fitted in the opening part of the
container.
[0011] In JP-A No. 9-7557 and JP-A No. 10-144268, the lids have the
taper peripheral edge and do not have flanges. If an electrode
terminal is fixed by caulking to the lid having such a shape, a
position of the lid in the container easily varies when the lid is
deformed by the caulking.
[0012] JP-A No. 2000-156219 illustrates, in FIG. 2, a sealed
battery using a lid body with a flange. In the battery according to
JP-A No. 2000-156219, the electrode terminal is hermetically sealed
to the lid body via an insulating material. Thus, the problem of
deformation of the lid body caused by the caulking does not occur
in the battery according to JP-A No. 2000-156219.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is an exploded perspective view of a main part of a
battery according to a first embodiment;
[0014] FIG. 2 is a perspective view of a lead used in the battery
according to the first embodiment;
[0015] FIG. 3 is a perspective view showing a main part of a
battery according to a second embodiment;
[0016] FIG. 4 is a perspective view of a lead used in the battery
according to the second embodiment;
[0017] FIG. 5 is a perspective view showing a lid on which the
positive and negative electrode leads shown in FIG. 4 are
fixed;
[0018] FIG. 6 is a perspective view showing a main part of an
electrode group having current collector tabs to which middle leads
are joined;
[0019] FIG. 7 is a perspective view showing a main part of a
battery according to another aspect in the second embodiment;
[0020] FIG. 8 is a perspective view showing a main part of an
electrode group having current collector tabs to which middle leads
are not joined;
[0021] FIG. 9 is a perspective view of a lead used in a battery
according to a third embodiment;
[0022] FIG. 10A is a top view of an angular battery according to a
fourth embodiment;
[0023] FIG. 10B is a cross-sectional view of a main part of the
angular battery according to the fourth embodiment, which is cut
along a long side direction;
[0024] FIG. 10C is a cross-sectional view of a main part of the
angular battery according to the fourth embodiment, which is cut
along a short side direction;
[0025] FIG. 11A is a top view of an angular battery according to a
fifth embodiment;
[0026] FIG. 11B is a cross-sectional view of a main part of the
angular battery of the fifth embodiment, which is cut along a long
side direction;
[0027] FIG. 11C is a cross-sectional view of a main part of the
angular battery according to the fifth embodiment, which is cut
along a short side direction;
[0028] FIG. 12A is a top view of a lid used in the angular battery
according to the fifth embodiment;
[0029] FIG. 12B is a cross-sectional view of the lid used in the
angular battery according to the fifth embodiment, which is cut
along a long side direction;
[0030] FIG. 12C is a cross-sectional view of the lid used in the
angular battery according to the fifth embodiment, which is cut
along a short side direction;
[0031] FIG. 13A is a top view of an opening-sealing member used in
the angular battery according to the fifth embodiment;
[0032] FIG. 13B is a cross-sectional view of the opening-sealing
member used in the angular battery according to the fifth
embodiment, which is cut along a long side direction;
[0033] FIG. 13C is a cross-sectional view of the opening-sealing
member used in the angular battery according to the fifth
embodiment, which is cut along a short side direction;
[0034] FIG. 14 is a perspective view showing a lead used in
Comparative Example 1;
[0035] FIG. 15 is a top view of a lid used in an angular battery
according to Comparative Example 3;
[0036] FIG. 16 is a top view of an opening-sealing member used in
the angular battery according to Comparative Example 3;
[0037] FIG. 17A is a top view of the angular battery of Comparative
Example 3;
[0038] FIG. 17B is a cross-sectional view of the angular battery
according to Comparative Example 3, which is cut along a long side
direction;
[0039] FIG. 17C is a cross-sectional view of the angular battery
according to Comparative Example 3, which is cut along a short side
direction;
[0040] FIG. 18 is a top view of a lid used in an angular battery
according to Comparative Example 4;
[0041] FIG. 19 is a top view of an opening-sealing member used in
an angular battery according to Comparative Example 4;
[0042] FIG. 20A is a top view of the angular battery according to
Comparative Example 4;
[0043] FIG. 20B is a cross-sectional view of the angular battery
according to Comparative Example 4, which is cut along a long side
direction; and
[0044] FIG. 20C is a cross-sectional view of the angular battery
according to Comparative Example 4, which is cut along a short side
direction.
DETAILED DESCRIPTION
[0045] In general, according to one embodiment, there is provided a
battery comprising a container; an electrode group comprising a
positive electrode and a negative electrode and being accommodated
in the container; a plurality of current collector tabs extended
from a plurality of points of a current collector of at least one
electrode of the positive electrode and the negative electrode in
the electrode group; a lid closing an opening part of the
container; a lead comprising a current collector tab junctional
part connected with the current collector tabs electrically, a lid
junctional part fixed to the lid, and a vibration absorber part
linking the current collector tab junctional part to the lid
junctional part; and a safety valve equipped on the lid.
[0046] According to another embodiment, there is provided a
production method of an angular battery. The battery comprises an
angular tube-shaped metal container having a bottom; a positive
electrode and a negative electrode accommodated in the container; a
lid placed on an opening part of the container; and a terminal
fixed to the lid by caulking and connected to the positive
electrode or the negative electrode electrically. The lid comprises
a bottom placed in the opening part of the container, and a stair
part located above the bottom and protruding outward beyond the
bottom. The method comprises placing the bottom of the lid in the
opening part of the container accommodating the positive electrode
and the negative electrode, and placing the stair part of the lid
on an upper end of a side wall of the container; and irradiating a
laser from a direction vertical to a surface at which the stair
part of the lid is overlaid on the upper end of the side wall of
the container to weld the stair part of the lid to the upper end of
a side wall of the container by laser welding.
[0047] Battery in embodiments will be explained below, referring to
the drawings. The embodiments are not limited to these
embodiments.
First Embodiment
[0048] FIG. 1 is an exploded perspective view of a sealed angular
nonaqueous electrolyte secondary battery. This battery has a
container 1, an electrode group 2 accommodated in the container 1,
a nonaqueous electrolyte solution (not shown in the drawing)
contained in the container 1, a lid 5 closing an opening part of
the container 1, a positive electrode terminal 6 and a negative
electrode terminal 7 equipped on the lid 5, and a safety valve 21
equipped on the lid 5.
[0049] The container 1 is an angular tube-shaped exterior can
having a bottom. The container 1 can be formed from, for example, a
metal such as aluminum, aluminum alloy, iron or stainless
steel.
[0050] The electrode group 2 has a flat shape, and contains a
positive electrode, a negative electrode, and a separator located
between the positive electrode and the negative electrode. The
electrode group 2 is produced, for example, by spirally winding a
laminate in which the separator is sandwiched between the positive
electrode and the negative electrode, and subjecting the resulting
product to a pressure molding. The electrode group 2, which has
been spirally wound, is fixed with a binding off tape.
[0051] The positive electrode has a positive electrode current
collector, a positive electrode active material layer, and a
positive electrode current collector tab 8. The positive electrode
current collector has a belt-like shape. The positive electrode
active material layer is formed on at least one surface of the
positive electrode current collector. The positive electrode
current collector tab 8 has a strip shape which extends from
multiple points on long sides of the positive electrode current
collector in a short side direction.
[0052] The negative electrode has a negative electrode current
collector, a negative electrode active material layer, and a
negative electrode current collector tab 9. The negative electrode
current collector has a belt-like shape. The negative electrode
active material layer is formed on at least one surface of the
negative electrode current collector. The negative electrode
current collector tab 9 has a strip shape which extends from
multiple points on long sides of the negative electrode current
collector in a short side direction.
[0053] The positive and negative electrode current collector tabs
8, 9 may be each formed by punching the current collectors. The
current collectors and the current collector tabs are formed from,
for example, a metal foil. The thickness of the metal foil, i.e.,
the thickness of one current collector tab is desirably from 5
.mu.m or more and 50 .mu.m or less. When the thickness is 5 .mu.m
or more, breakage of the current collector and the current
collector tab during production can be prevented, and high current
collection efficiency can be realized. The melting of the current
collector tab which occurs when a large electric current flows can
also be avoided. When the thickness is 50 .mu.m or less, the number
of windings of the laminate can be increased while the increase of
the thickness of the electrode group is inhibited. The thickness of
the metal foil is preferably 10 .mu.m or more and 20 .mu.m or less.
The material of the metal foil is selected depending on the kind of
the active material used in the positive electrode and the negative
electrode, and for example, aluminum, aluminum alloy, copper or
copper alloy may be used.
[0054] The multiple positive electrode current collector tabs 8 are
sandwiched together by a positive electrode backup lead 14 which is
bent in a U-shaped form.
[0055] This positive electrode backup lead 14 is also referred to
as a "positive electrode protecting lead." Similarly, the negative
electrode current collector tabs 9 are sandwiched together by a
negative electrode backup lead 15 which is bent in a U-shaped form.
The negative electrode backup lead 15 is also referred to as a
"negative electrode protecting lead."
[0056] The positive electrode backup lead 14 is electrically
connected to the positive electrode current collector tab 8, and
the negative electrode backup lead 15 is electrically connected to
the negative electrode current collector tab 9 by a method such as
laser welding, ultrasonic joining or resistance welding, preferably
by the ultrasonic joining. The positive and negative electrode
backup leads 14 and 15 are desirably formed from the same materials
as those of the current collector tabs 8, 9 of the positive and
negative electrodes, respectively. The positive and negative
electrode backup leads 14 and 15 desirably have a thickness three
times or more that of either of one positive electrode current
collector tabs 8 or one negative electrode current collector tab 9,
respectively. The thickness is more preferably in the range of 0.05
mm or more and 0.6 mm or less, further more preferably 0.1 mm or
more and 0.5 mm or less.
[0057] An opening part of the container 1 is sealed with an
opening-sealing member 10. The opening-sealing member 10 includes
the positive electrode terminal 6, the negative electrode terminal
7, gaskets 13, the lid 5, a positive electrode inner insulator 53,
a negative electrode inner insulator 54, a positive electrode lead
3 and a negative electrode lead 4. Rectangular depressions 19 are
provided in an outside surface of the lid 5 for storing the gaskets
13 therein. The positive electrode terminal 6 is stored in one
depression 19 through the gasket 13, and the negative electrode
terminal 7 is stored in the other depression 19 through the gasket
13. A through hole 20 is formed in each depression 19. An inlet 17
for introducing an electrolyte solution is opened in the lid 5, and
after the electrolyte solution is introduced, the inlet is sealed
with a sealing lid 18.
[0058] The positive electrode lead 3 and the negative electrode
lead 4 are placed inside the container 1. The positive and negative
electrode leads 3 and 4 have current collector tab junctional parts
3b and 4b to electrically connect the positive and negative
electrode leads 3 and 4 to the current collector tabs 8, 9; lid
junctional parts 3a and 4a to fix the positive and negative
electrode leads 3 and 4 to lid 5; and vibration absorber parts to
link the current collector tab junctional parts 3b and 4b to the
lid junctional parts 3a and 4a.
[0059] FIG. 2 shows the positive or negative electrode lead 3 (4)
used in the battery of the first embodiment. FIG. 2 shows the
positive or negative electrode lead 3 (4) in an opposite direction
to an installing direction of the lead in the battery, and thus the
lid junctional part 3a (4a) is located below. The positive and
negative electrode lead 3 (4) have the lid junctional part 3a (4a),
the current collector tab junctional part 3b (4b) and the vibration
absorber part 3c (4c). The lid junctional part 3a (4a) has an
almost rectangular plate-like shape whose one corner is chamfered.
The current collector tab junctional part 3b (4b) has a rectangular
plate-like shape. The area of the lid junctional part 3a (4a) is
smaller than that of the current collector tab junctional part 3b
(4b). The vibration absorber part 3c (4c) has a rectangular
plate-like shape, and is located between the lid junctional part 3a
(4a) and the current collector tab junctional part 3b (4b).
[0060] The positive and negative electrode lead 3 (4) are bent at
an almost right angle along a side separating the vibration
absorber part 3c (4c) from the lid junctional part 3a (4a). The
vibration absorber part 3c (4c) is placed almost perpendicularly to
the lid junctional part 3a (4a) by this placement. The vibration
absorber part 3c (4c) and the current collector tab junctional part
3b (4b) are located on the same plane. Thus, the current collector
tab junctional part 3b (4b) is located almost perpendicularly to
the lid junctional part 3a (4a).
[0061] The length X1 of the vibration absorber part 3c (4c) in a
longer direction is shorter than the length Y1 of the current
collector tab junctional part 3b (4b) in a longer direction, and
shorter than the length W1 of the lid junctional part 3a (4a) in a
longer direction. In this regard, the term "longer direction"
refers to a direction crossing at a right angle to an extending
direction of the positive or negative electrode current collector
tab 8 or 9. The shapes of the lid junctional part 3a (4a), the
current collector tab junctional part 3b (4b) and the vibration
absorber part 3c (4c) are not limited to the rectangular or almost
rectangular shape, and can be a square shape. In any shape, the
length of the vibration absorber part 3c (4c) in the longer
direction is shorter than the lengths of the lid junctional part 3a
(4a) and of the current collector tab junctional part 3b (4b) in
the longer direction.
[0062] The lid junctional part 3a has a through hole 3e. This
through hole 3e is the hole for installing an axis of the positive
electrode terminal 6. The lid junctional part 4a has a through hole
4e. This through hole 4e is the hole for installing an axis of the
negative electrode terminal 7.
[0063] As shown in FIG. 1, with regard to the positive electrode
lead 3, the lid junctional part 3a is laid on the inner insulator
53, which is placed on an inner surface of the lid 5. The current
collector tab junctional part 3b extends downward from a bent part
between it and the lid junctional part 3a. With regard to the
negative electrode lead 4, the lid junctional part 4a is laid on
the inner insulator 54, which is placed on an inner surface of the
lid 5. The current collector tab junctional part 4b extends
downward from a bent part between it and the lid junctional part
4a.
[0064] The inner insulator 53 for the positive electrode may have a
rectangular plate-like shape. The inner insulator 53 for the
positive electrode has a through hole 53a which communicates with
the through hole 20 of the lid 5 and with the through hole 3e of
the positive electrode lead 3. The inner insulator 53 for the
positive electrode is placed between the inner surface of the lid 5
and the lid junctional part 3a of the positive electrode lead 3,
and insulates the lid 5 and the positive electrode lead 3.
[0065] The inner insulator 54 for the negative electrode may have a
rectangular plate-like shape. The inner insulator 54 for the
negative electrode has a through hole 54a which communicates with
the through hole 20 of the lid 5 and with the through hole 4e of
the negative electrode lead 4, and a through hole 54b which
communicates with the inlet for introducing a solution 17 of the
lid 5. The inner insulator 54 for the negative electrode is placed
between the inner surface of the lid 5 and the lid junctional part
4a of the negative electrode lead 4, and insulates the lid 5 and
the negative electrode lead 4.
[0066] The positive electrode terminal 6 has a rivet-like shape,
and specifically it has a flange 6a and an axis 6b which extends
from the flange 6a. The axis 6b of the positive electrode terminal
6 is inserted into the through hole 20 of the lid 5 through the
gasket 13, and is also inserted into the through hole 53a of the
inner insulator 53 and the through hole 3e of the positive
electrode lead 3. The axis is fixed to them by caulking. Similarly,
the negative electrode terminal 7 has a rivet-like shape, and
specifically it has a flange 7a and an axis 7b which extends from
the flange 7a. The axis 7b is inserted into the through hole 20 of
the lid 5 through the gasket 13, and is also inserted into the
through hole 54a of the inner insulator 54 and the through hole 4e
of the negative electrode lead 4. The axis is fixed to them by
caulking. Thus, the positive and negative electrode terminals 6 and
7, and the lid 5 are fixed in a state in which the insulation and
the air tightness are secured. In addition, the positive and
negative electrode terminal 6 and 7 are fixed to the positive
electrode lead 3 and the negative electrode lead 4, respectively,
in a state in which an electrical connection is secured.
[0067] The positive electrode backup lead 14, which grips a tip of
the positive electrode current collector tab 8, is fixed to the
current collector tab junctional part 3b of the positive electrode
lead 3 in a state in which an electric connection is maintained. On
the other hand, the negative electrode backup lead 15, which grips
a tip of the negative electrode current collector tab 9, is fixed
to the current collector tab junctional part 4b of the negative
electrode lead 4 in a state in which an electric connection is
maintained.
[0068] The electric connection of the positive electrode lead 3
with the positive electrode backup lead 14, and the electric
connection of the negative electrode lead 4 with the negative
electrode backup lead 15 may be performed by using a method such as
laser welding, ultrasonic joining, or resistance welding. The
connection may be preferably performed by the ultrasonic
joining.
[0069] The lid 5 has a rectangular plate-like shape. The lid 5 is
welded to an opening part of the container 1, for example, by seam
welding with a laser. The lid 5 may be formed from a metal such as
aluminum, aluminum alloy, iron or stainless steel. The lid 5 is
desirably formed from the same kind of metal as that of the
container 1.
[0070] The lid 5 has the safety valve 21 for releasing an inner
pressure of the battery. The safety valve 21 is a rectangular
depression. A cross-shaped groove 22 is formed on a bottom of the
depression. This part of the groove 22 is thin. The shape of the
safety valve is not limited to this shape, and may be any shape so
long as it is capable of releasing gas to the outside by breakage
caused by the increased internal pressure of the container.
[0071] The gasket 13 is formed from, for example, polypropylene
(PP), a fluorine-containing thermoplastic resin, or the like.
Examples for the fluorine-containing thermoplastic resin include
tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA),
tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and the
like.
[0072] The positive electrode terminal 6 and the negative electrode
terminal 7 are formed from, for example, aluminum or aluminum
alloy. In a case of a lithium ion secondary battery using a carbon
material as the negative electrode active material, aluminum or
aluminum alloy can be used as a material for the positive electrode
terminal, and a metal such as copper, nickel or a nickel-plated
iron can be used as a material for the negative electrode
terminal.
[0073] The positive electrode lead 3 is formed from an electrically
conductive material. As such a material, for example, aluminum or
aluminum alloy may be used. The material can be arbitrarily changed
depending on the kind of the positive electrode active
material.
[0074] The negative electrode lead 4 is formed from an electrically
conductive material. As such a material, aluminum or aluminum alloy
may be used when the negative electrode active material is lithium
titanate. The material can be arbitrarily changed depending on the
kind of the negative electrode active material.
[0075] The electrode group 2 is vibrated in the container 1 when an
impact or vibration is applied to the nonaqueous electrolyte
secondary battery from the outside, for example, in the case it
loaded into an electric car. The vibration is transmitted to the
lid 5 through the positive and negative electrode current collector
tabs 8 and 9, and the positive and negative electrode leads 3 and
4. In the nonaqueous electrolyte secondary battery of the first
embodiment described above, however, the positive and negative
electrode leads 3 and 4 have the vibration absorber parts 3c and
4c. The vibration absorber parts 3c and 4c can absorb the
vibration. Hence, the transmission of the vibration to the lid 5
can be inhibited; as a result, breakage of the safety valve 21
equipped on the lid 5 due to the vibration can be suppressed.
[0076] Further, since the vibration is not transmitted to the lid
and thus there is no risk of breakage of the safety valve in the
battery of the first embodiment, it is possible to join the
positive and negative electrode current collector tabs 8 and 9 to
the current collector tab junctional parts 3b and 4b of the
positive and negative electrode leads 3 and 4 by ultrasonic
joining, respectively. This eliminates a welding step of a middle
lead to the current collector tab, and thus the number of
production steps can be decreased. Further, because the middle lead
is unnecessary, the number of the parts can be decreased and the
weight energy density of the battery can be improved.
[0077] The lead used in the battery of the first embodiment
preferably has a shape satisfying the following formula (1):
0.12.ltoreq.X1/Y1.ltoreq.0.2 (1)
wherein X1 is a length of the vibration absorber part 3c and 4c in
a direction crossing at a right angle to an extending direction of
the current collector tab 8 and 9; and Y1 is a length of the
current collector tab junctional part 3b and 4b in a direction
crossing at a right angle to an extending direction of the current
collector tab 8 and 9. As illustrated in FIG. 2, X1 is a length of
the vibration absorber part 3c (4c) in a longer direction. Y1 is a
length of the current collector tab junctional part 3b (4b) in a
longer direction.
[0078] The vibration absorber part satisfying X1/Y1 of 0.2 or less
is low in rigidity, and can sufficiently absorb the vibration. When
X1/Y1 is 0.12 or more, the strength of the lead can be maintained
appropriately.
[0079] When the lead which satisfies the formula (1) described
above and has a shape such that it is bent along the side
separating the vibration absorber part from the lid junctional part
is used, it can be further inhibited from transmitting the
vibration of the electrode group to the lid through the current
collector tabs, and thus breakage of the safety valve can be
further suppressed. In addition, the lead having the shape
described above has a resistance value which is almost the same as
that of a lead having no vibration absorber part, and thus it can
provide an excellent battery performance.
[0080] The length of the vibration absorber part in a longer
direction is preferably a length sufficient to maintain the
strength of the lead. This can prevent breakage of the lead.
[0081] A length M1 of the vibration absorber part in a direction
crossing at a right angle to the longer direction is not
particularly limited, and can be, for example, from 0.8 to 1.2 mm.
The transmission of the vibration can be inhibited with an increase
in the value of M1. The value of M1 may be arbitrarily determined
depending on the space in which the lead is set and the strength of
the lead.
[0082] The sizes of the lead, as shown in FIG. 2, including X1, Y1,
a length of the lid junctional part 3a (4a) in a longer direction
(W1), a length of the lid junctional part 3a (4a) in a direction
crossing at a right angle to the longer direction (R1), and a
length of the current collector tab junctional part 3b (4b) in a
direction crossing at a right angle to the longer direction (Z1)
are not particularly limited, and they may be arbitrarily
determined depending on the sizes of the battery and the electrode,
and the like.
[0083] The thickness of the lead is not particularly limited, and
can be, for example, from 0.5 to 1 mm. The transmission of the
vibration can be inhibited with an increase in the thickness of the
lead. The thickness of the lead may be arbitrarily determined
depending on the space in which the lead is set and the strength of
the lead.
[0084] According to the embodiment described above, there can be
provided a nonaqueous electrolyte battery with breakage of the
safety valve equipped on the lid caused by the transmission of the
vibration to the lid of the battery is prevented.
Second Embodiment
[0085] Next, a nonaqueous electrolyte secondary battery of a second
embodiment will be explained referring to FIG. 3. In FIG. 3, the
same numbers as those in FIGS. 1 and 2 described above denote the
same members and the explanations thereof are omitted. FIG. 4 is a
perspective view showing a positive and negative electrode leads 3
and 4 used in the battery shown in FIG. 3.
[0086] The positive and negative electrode lead 3 (4) has a lid
junctional part 3a (4a), a current collector tab junctional part 3b
(4b), and a vibration absorber part 3c (4c). The vibration absorber
part 3c (4c) has an almost quadrilateral shape, and is placed along
a side in a short side direction of a container 1. The lid
junctional part 3a (4a) has a rectangular shape, and extends
vertically from the vibration absorber part 3c (4c). The lid
junctional part 3a (4a) is formed by bending along a first side 23
of the vibration absorber part 3c (4c) (an upper side in FIG. 4).
The current collector tab junctional part 3b (4b) has a rectangular
shape, and extends vertically from the vibration absorber part 3c
(4c). The current collector tab junctional part 3b (4b) is formed
by bending along a second side 24 of the vibration absorber part 3c
(4c). The first side 23 and the second side 24 are adjacent to each
other. The lid junctional part 3a (4a) and the current collector
tab junctional part 3b (4b) extend in the same direction. There is
a gap 25 between the lid junctional part 3a (4a) and the current
collector tab junctional part 3b (4b), and the lid junctional part
3a (4a) is not directly brought into contact with the current
collector tab junctional part 3b (4b).
[0087] The lid junctional part 3a has a through hole 3e. This
through hole 3e is the hole for installing an axis of a positive
electrode terminal 6. The lid junctional part 4a has a through hole
4e. This through hole 4e is the hole for installing an axis of a
negative electrode terminal 7.
[0088] As shown in FIG. 5, the positive and negative electrode
leads 3 and 4 are laid on a lid 5 through an inner insulator which
is not shown, and are fixed by caulking with the positive and
negative electrode terminals 6 and 7. Specifically, the lid
junctional part 3a of the positive electrode lead 3, the inner
insulator (not shown in FIG. 5) and the lid 5 are laminated in this
order, and the axis of the positive electrode terminal 6 is
inserted into a through hole of the inner insulator and the through
hole 3e of the lid junctional part 3a. The positive electrode lead
3 is placed so that the longer direction of the current collector
tab junctional part 3b is the same as the longer direction of the
lid 5, and the surface of the vibration absorber part 3c is almost
parallel to the short side direction of the lid 5. The lid
junctional part 4a of the negative electrode lead 4, the inner
insulator (not shown in FIG. 5) and the lid 5 are laminated in this
order, and the axis of the negative electrode terminal 7 is
inserted into the through hole of the inner insulator and the
through hole 4e of the lid junctional part 4a. The negative
electrode lead 4 is placed so that the longer direction of the
current collector tab junctional part 4b is the same as the longer
direction of the lid 5, and the surface of the vibration absorber
part 4c is almost parallel to the short side direction of the lid
5.
[0089] As shown in FIG. 6, positive and negative electrode current
collector tabs 8 and 9 are respectively sandwiched by positive and
negative electrode backup leads 14 and 15 which are bent in
U-shaped forms. The positive and negative electrode backup leads 14
and 15 are joined to a middle lead 17 having a rectangular
plate-like shape together with the positive and negative electrode
current collector tab 8 and 9, respectively. The positive and
negative electrode backup leads 14 and 15 may be joined to the
middle lead 17 by a method such as laser welding, ultrasonic
joining or resistance welding, and are preferably joined by the
ultrasonic joining.
[0090] The positive and negative electrode current collector tab 8
and 9 and the backup leads 14 and 15 are joined to one surface each
of the middle lead 17. As shown in FIG. 3, the other surface of the
middle lead 17 is joined to the current collector tab junctional
part 3b or 4b of the positive or negative electrode lead. The
positive and negative electrode leads 3 and 4 may be joined to the
middle lead 17 by a method such as laser welding, ultrasonic
joining or resistance welding.
[0091] The positive and negative electrode leads 3 and 4 used in
this embodiment are, as shown in FIG. 4, bent along a first side 23
which separates the vibration absorber part 3c (4c) from the lid
junctional part 3a (4a) and bent along a second side 24 which is
adjacent to the first side 23 and separates the vibration absorber
part 3c (4c) from the current collector tab junctional part 3b
(4b), The positive and negative electrode leads 3 and 4 have a gap
25 between the lid junctional part 3a (4a) and the current
collector tab junctional part 3b (4b). When the lead has such a
shape, a distance between a junctional part of the positive and
negative electrode leads 3 and 4 to the lid 5 and a junctional part
of the positive and negative electrode leads 3 and 4 to the
positive or negative electrode current collector tab 8 or 9 can be
sufficiently large while maintaining a compact size enabling them
to be accommodated in the container 1, and thus the transmission of
vibration can be inhibited. The nonaqueous electrolyte secondary
battery of the second embodiment using such positive and negative
electrode leads 3 and 4 inhibits the transmission of the vibration
of an electrode group 2 to the lid 5 through the positive and
negative electrode current collector tabs 8 and 9, and the positive
and negative electrode leads 3 and 4, and thus the breakage of a
safety valve can be suppressed.
[0092] Further, since the vibration is not transmitted to the lid
and thus there is no risk of breakage of the safety valve, it is
possible to join the positive and negative electrode current
collector tab 8 and 9 to the current collector tab junctional part
3b and 4b of the positive and negative electrode lead by ultrasonic
joining, respectively. Thus, the number of production steps and the
number of parts can be decreased.
[0093] Since the positive or negative electrode lead 3 (4) having
the shape described above has vibration absorber part 3c (4c) with
a large area, the strength is high and it is hard to break.
[0094] The positive or negative electrode lead 3 (4) shown in FIG.
4 has a notch 26 around a corner at which the first side of the
vibration absorber part 3c (4c) intersects the second side, but the
lead is not limited thereto, and may have a shape with no
notch.
[0095] As shown in FIG. 4, the sizes of the lead include a length
(Z2) of the current collector tab junctional part 3b (4b) in a
direction crossing at a right angle to the extending direction of
the current collector tab 8 or 9; a length (Y2) of the current
collector tab junctional part 3b (4b) in an extending direction of
the current collector tab 8 or 9; a length (W2) of the lid
junctional part 3a (4a) in a direction crossing at a right angle to
an extending direction of the current collector tab; a length (Q2)
of the vibration absorber part 3c (4c) parallel to the first side;
and a length (R2) of the vibration absorber part 3c (4c) parallel
to the first side of the part at which the notch 26 is located. W2
is a length of the lid junctional part 3a (4a) in a longer
direction, which is a length in the same direction as a long side
direction of the container 1. These sides of the lead are not
particularly limited, and may be arbitrarily determined depending
on the sizes of the battery and the electrode, and the like.
[0096] The thickness of the lead is not particularly limited, and
can be, for example, from 0.5 to 1 mm. The transmission of
vibration can be inhibited with an increase in the thickness of the
lead. The thickness of the lead may be arbitrarily determined
depending on the space in which the lead is set and the strength of
the lead.
[0097] Next, a nonaqueous electrolyte secondary battery of another
aspect of the second embodiment will be explained referring to
FIGS. 7 and 8. In the battery of this embodiment, positive and
negative electrode leads 3 and 4 having the shape shown in FIG. 4
are used. The positive and negative electrode leads 3 and 4 are
fixed on a lid 5 in the manner as shown in FIG. 5. As shown in FIG.
7, in the battery of the aspect, the positive and negative
electrode leads 3 and 4 are joined to positive and negative
electrode backup leads 14 and 15, respectively, without having a
middle lead interposed.
[0098] As shown in FIG. 8, positive and negative electrode current
collector tabs 8 and 9 are respectively sandwiched by positive and
negative electrode backup leads 14 and 15 which are bent in
U-shaped forms. As shown in FIG. 7, one surface of the positive and
negative electrode backup leads 14 and 15 is respectively joined to
a current collector tab junctional part 3b and 4b of the positive
and negative electrode leads 3 and 4. The joining may be performed
by a method such as laser welding, ultrasonic joining or resistance
welding, and it is preferably performed by the ultrasonic
joining.
[0099] Conventionally, when positive and negative electrode leads 3
and 4 were respectively joined to positive and negative electrode
backup leads 14 and 15 by ultrasonic joining, vibration was
transmitted to a lid, resulting in a risk of breakage of a safety
valve. However, the battery of this embodiment can inhibit the
vibration transmitted to the lid, and therefore, the positive and
negative electrode leads 3 and 4 can be joined respectively to the
positive and negative electrode backup leads 14 and 15 by
ultrasonic joining. As a result, it is possible to decrease the
number of production steps and the number of parts.
[0100] According to the embodiment described above, the nonaqueous
electrolyte battery which prevents the breakage of the safety valve
provided on the lid, caused by the transmission of vibration to the
lid of the battery, can be provided.
Third Embodiment
[0101] Next, a nonaqueous electrolyte secondary battery of a third
embodiment will be explained referring to FIGS. 3 and 9. In FIG. 9,
the same numbers as those in FIG. 4 described above denote the same
members and the explanations thereof are omitted.
[0102] As shown in FIG. 9, a positive or negative electrode lead 3
(4) used in the nonaqueous electrolyte battery of the third
embodiment has a shape which is the same as that of the positive or
negative electrode lead 3 (4) used in the second embodiment, and
further has a second vibration absorber part 3d (4d) which is
brought into contact with a second side 24. The second vibration
absorber part 3d (4d) is disposed between a part at which a current
collector tab junctional part 3b (4b) is joined to a positive and
negative electrode current collector tabs 8 and 9 or a middle lead,
and a vibration absorber part 3c (4c); in other words, the second
vibration absorber part 3d (4d) is not disposed at the part at
which the current collector tab junctional part 3b (4b) is joined
to the positive and negative electrode current collector tabs 8 and
9 or the middle lead.
[0103] The positive and negative electrode leads used in the
battery of the third embodiment preferably satisfy the following
formula (2):
0.5.ltoreq.X2/Y2<1 (2)
wherein X2 is a length of the second vibration absorber part 3d
(4d) in the same direction as an extending direction of the current
collector tabs 8 and 9; and Y2 is a length of the current collector
tab junctional part 3b (4b) in the same direction as the extending
direction of the current collector tabs 8 and 9. As illustrating in
FIG. 9, X2 shows a length of the second vibration absorber part 3d
(4d) crossing at a right angle to a longer direction, and Y2 shows
a length of the current collector tab junctional part 3b (4b)
crossing at a right angle to a longer direction. The longer
direction of the second vibration absorber part 3d (4d) is the same
as the longer direction of the current collector tab junctional
part 3b (4b).
[0104] The vibration absorber part having X2/Y2 of less than 1 has
a low rigidity and thus can absorb vibration. When X2/Y2 is 0.5 or
more, the strength of lead can be appropriately maintained.
[0105] In the lead having the shape described above, a distance
between a junctional part of the lead and lid and a junctional part
of the lead and the current collector tab is large while the size
is in a compact shape for accommodating them in the container 1. In
addition, because the lead has the second vibration absorber part
3d (4d), the transmission of vibration can be further inhibited.
When the lead having the shape described above is used, it is
possible to inhibit the transmission of the vibration of an
electrode group to the lid through the current collector tab,
whereby the breakage of the safety valve can be suppressed. In
addition, because the vibration is not transmitted to the lid and
there is no risk of breakage of the safety valve, it is possible to
join the positive and negative electrode current collector tabs 8
and 9 to the current collector tab junctional part 3b and 4b of the
positive and negative electrode leads 3 and 4 by ultrasonic
joining, respectively.
[0106] The length M2 of the second vibration absorber part 3d (4d)
in the longer direction is not particularly limited, and it can be,
for example, from 4 to 8 mm. The transmission of vibration can be
inhibited with an increase in the value of M2. The value of M2 may
be arbitrarily determined depending on the strength of the
lead.
[0107] As shown in FIG. 9, the sizes of the lead include a length
(Z2) of the current collector tab junctional part 3b (4b) in a
direction crossing at a right angle to an extending direction of
the current collector tabs 8 and 9; a length (W2) of the lid
junctional part 3a (4a) in a direction crossing at a right angle to
an extending direction of the current collector tab; a length (Q2)
of the vibration absorber part 3c (4c) in a direction parallel to a
first side thereof; and a length (R2) of the vibration absorber
part 3c (4c) parallel to the first side of the part at which the
notch 26 is located. W2 is a length of the lid junctional part 3a
(4a) in a longer direction, which is a length in the same direction
as a long side direction of the container 1. The sizes of the lead
are not particularly limited, and may be arbitrarily determined
depending on the sizes of the battery and the electrode, and the
like.
[0108] The thickness of the lead is not particularly limited, and
can be, for example, from 0.5 to 1 mm. The transmission of
vibration can be inhibited with an increase in the thickness of the
lead, and it may be arbitrarily determined depending on the space
in which the lead is set and the strength of the lead.
Fourth Embodiment
[0109] Next, an angular nonaqueous electrolyte battery according to
a fourth embodiment will be explained. As shown in FIGS. 10A, 10B
and 10C, this battery has a container 31, an electrode group 32
accommodated in the container 31, a nonaqueous electrolyte solution
(not shown in the drawings) contained in the container 31, a lid 33
which closes an opening part of the container 31, and a positive
electrode terminal 34 and a negative electrode terminal 35 which
are equipped on the lid 33. The container 31 has an angular tube
shape having a bottom, and is an exterior can formed from, for
example, a metal such as aluminum, aluminum alloy, iron or
stainless steel.
[0110] The electrode group 32 contains a positive electrode (not
shown in the drawings), a negative electrode (not shown in the
drawings), and a separator (not shown in the drawings) which is
placed between the positive electrode and the negative electrode,
and has a flat shape. The electrode group 32 is produced, for
example, by putting the separator between the positive electrode
and the negative electrode, spirally winding them, and then
pressure molding them into a flat shape.
[0111] As shown in FIG. 10B, a bottom 36 of the lid 33 is defined
by a thickness from a bottom face to a stair part 37, and is placed
inside the opening part of the container 31. A part located above
the bottom 36 of the lid 33 is a stair part 37 (hereinafter
referred to as a "flange 37") which protrudes outward beyond the
bottom. The lid 33 has a positive electrode terminal 34, which
projects convexly to the outside surface (i.e., the top surface
side), and has a through hole. The negative electrode terminal 35
is fixed in the through hole by caulking. The lid 33 is formed
from, for example, a metal such as aluminum, aluminum alloy, iron
or stainless steel. The lid 33 is desirably formed from the same
metal as the container 31.
[0112] As shown in FIGS. 10B and 10C, the negative electrode
terminal 35 has a rivet-like shape. Specifically, it has a head
35a, and an axis 5b which extends from the head 35a. The negative
electrode terminal 35 is fixed in the through hole of the lid 33
through an insulating gasket 39 by caulking.
[0113] A rectangular insulating plate 40 is placed on the bottom
face of the lid 33. The insulating plate 40 has a through hole, and
the axis 35b of the negative electrode terminal 35 is fixed in the
through hole by caulking.
[0114] A rectangular negative electrode lead 41 is placed on an
undersurface of the insulating plate 40. The negative electrode
lead 41 has a through hole, and the axis 35b of the negative
electrode terminal 35 is fixed in the through hole by caulking.
[0115] One end of a negative electrode tab 42 is electrically
connected to a negative electrode of the electrode group 32, and
the other end thereof is electrically connected to the negative
electrode lead 41. When the tab has such a structure, the negative
electrode of the electrode group 32 is electrically connected to
the negative electrode terminal 35 and the negative electrode lead
41 through the negative electrode tab 42.
[0116] The negative electrode terminal 35, the negative electrode
lead 41 and the negative electrode tab 42 are formed from an
electrically conductive material, and the material is changed
depending on the kind of the negative electrode active material.
When the negative electrode active material is lithium titanate,
aluminum or aluminum alloy may be used.
[0117] The rectangular positive electrode lead 43 is electrically
connected to the positive electrode terminal 34 by fixing it on the
bottom face of the lid 33. One end of the positive electrode tab 44
is electrically connected to a positive electrode of the electrode
group 32, and the other end thereof is electrically connected to
the positive electrode lead 43. When the lead has such a structure,
the positive electrode of the electrode group 32 is electrically
connected to the positive electrode terminal 34 and the positive
electrode lead 43 through the positive electrode tab 44.
[0118] The positive electrode lead 43 and the positive electrode
tab 44 are formed from an electrically conductive material, and the
material can be changed depending on the kind of the positive
electrode active material, and for example, aluminum or aluminum
alloy may be used.
[0119] The bottom 36 of the lid 33 is placed in the opening part of
the container 31, and the flange 37 is placed above an upper end of
a side wall 31a of the container 31. The flange 37 of the lid 33 is
welded to the upper end of the side wall 31a of the container 31 by
laser seam welding. This enables the container 31 to be air-tightly
sealed by the lid 33.
[0120] A method for producing the angular battery of the fourth
embodiment will be explained below.
[0121] First, the electrode group 32 and other necessary members
are accommodated in the container 31. After the insulating gasket
39 is inserted in the through hole of the lid 33, the axis 35b of
the negative electrode terminal 35 is inserted into the insulating
gasket 39, and the through holes of the insulating plate 40 and the
negative electrode lead 41, and the axis 35b of the negative
electrode terminal 35 is deformed to have an enlarged diameter by
caulking. As a result, the axis 35b of the negative electrode
terminal 35 is fixed in the through hole of the lid 33 through the
insulating gasket 39 by caulking, and the insulating plate 40 and
the negative electrode lead 41 are fixed on the axis 35b of the
negative electrode terminal 35 by caulking.
[0122] The positive electrode of the electrode group 32 is
electrically connected to the positive electrode terminal 34 of the
lid 33 using the positive electrode tab 44, and the negative
electrode of the electrode group 32 is electrically connected to
the negative electrode terminal 35 of the lid 33 using the negative
electrode tab 42. The electrical connection method may include, for
example, laser welding, ultrasonic joining, resistance welding, and
the like.
[0123] Subsequently, the bottom 36 of the lid 33 is inserted inside
the opening part of the container 31, and the flange 37 of the lid
33 is placed at the upper end of a side wall 31a of the container
31. Laser seam welding is performed by irradiating a laser beam
from a tool 45 for welding to the flange 37 of the lid 33. A
direction of radiation L is set so as to be perpendicular to a
surface at which the flange 37 of the lid 33 is overlaid on the
upper end of a side wall 31a of the container 31. As a result, the
flange 37 of the lid 33 is welded on the upper end of a side wall
31a of the container 31 by laser seam welding.
[0124] When the negative electrode terminal 35 is fixed on the lid
33 by caulking, not only the negative electrode terminal 35 is
pressurized in an axial direction to deform to have an enlarged
diameter, but also the pressure is applied to a periphery of the
through hole. As a result, the side face of the long side of the
lid 33 is curved outward on a part corresponding to the through
hole. When the bottom 36 of the thus deformed lid 33 is inserted
into the opening part of the container 31, the bottom 36 of the lid
33 is not fitted to the side wall around the opening part of the
container 31, resulting in a gap between them. However, four sides
of the flange 37 of the lid 33 are all placed on the upper end of a
side wall 31a of the container 31, and thus, the flange 37 can
cover the opening part of the container 31. As a result, the gap
between the bottom 36 of the lid 33 and the opening part, i.e., the
inner surface of the side wall of the container 31 is not exposed
to the outside. In addition, when the welding is performed by
irradiating a laser toward the surface at which the upper end of a
side wall 31a of container 31 is overlaid on the flange 37 in a
vertical direction, welding defects resulting from the gap can be
decreased, and the container 31 can be air-tightly sealed with the
lid 33. Furthermore, the position of the lid 33 toward the
container 31 can be determined only by placing the flange 37 of the
lid 33 on the upper end of a side wall 31a of the container 31, and
therefore variation per product in a size such as a total height of
a battery or a height of a positive or negative electrode terminal
can be reduced.
[0125] When a so-called "overpick" is performed, in which the
flange 37 of the lid 33 is placed on the upper end of a side wall
31a of the container 31, and a laser is irradiated from a vertical
direction toward the surface at which the flange 37 is overlaid on
the container 31, i.e., from the top surface of the flange 37,
generation of cracks can be prevented and splashes can be decreased
at a depth of about the wall thickness of the container 31, and
accordingly a sufficient pressure capacity can be obtained. For
example, when the wall thickness of the container 31 (i.e., the
thickness of the container) is 0.5 mm, about 0.5 mm of penetration
depth is necessary. On the other hand, a pressure capacity in a
welded part of the lid 33 and the container 31 can be adjusted by
the wall thickness of the container 31 and a working pressure of
the safety valve equipped on the lid 33. Therefore, the penetration
to a depth which is the same as or greater than the wall thickness
of the container 31 is not necessary and the penetration depth may
be 0.5 mm or less. In addition, in the case of the overpick, a
welding apparatus can be biaxially controlled, and thus the
processing speed can be easily increased and the cost of equipment
can be reduced.
[0126] On the other hand, in a case of a so-called "sidepick" in
which welding is performed from a horizontal direction toward the
surface at which the flange 37 of the lid 33 is overlaid on the
upper end of a side wall 31a of the container 31, a problem arises
in which the flange 37 is not completely melted into the container
when a penetration depth is less than the wall thickness of the
container 31, and cracks are easily generated; in other words, a
penetration depth which is the same as or greater than the wall
thickness of the container 31 is necessary. For example, when the
container 31 has a wall thickness of 0.5 mm, a penetration of 0.5
mm or more is necessary. Additionally, in the case of the sidepick,
a welding apparatus is triaxially controlled, and thus it is hard
to increase the processing speed and reduce the cost of
equipment.
[0127] As stated above, the penetration depth in the case in which
the laser is irradiated from the vertical direction toward the
surface at which the flange 37 is overlaid on the container 31 can
be made less than that in the case in which the laser is irradiated
from the horizontal direction toward the overlaid surface. As a
result, the laser output can be set at a lower level, and it is
advantageous in terms of inhibition of the quantity of splashes
generated and an increase in the processing speed.
[0128] After the laser welding, an electrolyte solution is injected
from an inlet for injecting an electrolyte solution (not shown in
the drawing) equipped on the lid 33, and after that the inlet for
injecting a solution is sealed with a seal lid (not shown in the
drawing), thereby obtaining an angular nonaqueous electrolyte
battery. According to such a production method, a welding yield can
be improved.
[0129] The thickness T of the flange 37 of the lid 33 is desirably
a thickness which is the same as the wall thickness of the
container 31 or less, and it is more preferably within a range of
0.5 mm or less. Thus, a complete penetration depth of the flange 37
which is required in the overpick welding can be made less than the
wall thickness of the container 31, for example, 0.5 mm or less,
and thus the laser output can be further reduced.
[0130] The wall thickness of the container 31 is not particularly
limited so long as it is the same as the thickness T of the flange
37 or more.
[0131] The welding can be performed using a laser beam such as a
carbonic acid gas laser or YAG laser.
[0132] In a case of a lithium ion secondary battery using a carbon
material as the negative electrode active material, aluminum or
aluminum alloy is generally used as the material for the positive
electrode terminal, the positive electrode lead, the positive
electrode tab, and the like; and a metal such as copper, nickel or
nickel-plated iron is used as the material for the negative
electrode terminal, the negative electrode lead, the negative
electrode tab, and the like.
[0133] According to the fourth embodiment, a part of the lid 33 is
used as the positive electrode terminal 34, and the negative
electrode terminal 35 is attached to the lid 33 by caulking, but a
part of the lid 33 may be used as the negative electrode terminal
35, and the positive electrode terminal 34 may be attached to the
lid 33 by caulking. Alternatively, both of the positive and
negative electrode terminals 4 and 5 can be attached to the lid 33
by caulking.
[0134] According to the embodiment described above, the angular
battery having the lid with the electrode terminals attached
thereto by caulking can be provided and welding yields can be
improved in the production method thereof.
Fifth Embodiment
[0135] An angular nonaqueous electrolyte battery of a fifth
embodiment is shown in FIGS. 11A, 11B and 11C. FIG. 11 is a top
view of the angular battery of the fifth embodiment; FIG. 11B is a
cross-sectional view of a main part of the angular battery, which
is cut along a long side direction; and FIG. 11C is a
cross-sectional view of a main part of the angular battery, which
is cut along a short side direction. The battery according to this
embodiment has the same structure as that of the angular nonaqueous
electrolyte battery according to the fourth embodiment, except that
a shape of a lid and a method for attaching a positive electrode
terminal are different. Hereinafter, In the battery of the fifth
embodiment, the same numbers as those in the fourth embodiment
denote the same members and the explanations thereof are
omitted.
[0136] As shown in FIGS. 11A, 11B and 11C, in the battery according
to the embodiment, a positive electrode terminal 34 is fixed on a
lid 33 by caulking together with a negative electrode terminal
35.
[0137] As shown in FIGS. 12A, 12B and 12C, the lid 33 has a through
hole 38 to which the negative electrode terminal 35 is fixed by
caulking, and a through hole 46 to which the positive electrode
terminal 34 is fixed by caulking. As shown in FIG. 12A, a bottom 36
of the lid 33 has four depressions 47 on both side in a long side
direction. These four depression 47 are placed so that they form a
line with the through hole 38 or 46 in a short side direction of
the lid 33. By this placement, a part in which the through holes
38, 46 are crossed is made shorter than other parts, in a width of
the bottom 36 in a short side direction.
[0138] FIGS. 13A, 13B and 13C show an opening-sealing member. This
opening-sealing member is a member in which the positive and
negative electrode terminals 34, 35 are attached to the lid 33
having the shape shown in FIG. 12A, 12B and 12C by caulking. The
opening-sealing member contains the lid 33, the positive and
negative electrode terminals 34 and 35, an insulating gasket 39, an
insulating plate 40, and positive and negative electrode leads 43
and 41.
[0139] As shown in FIG. 13B, the positive electrode terminal 34 has
a rivet-like shape. Specifically, it has a head 34a and an axis 34b
which extends from the head 34a. The positive electrode terminal 34
is fixed in the through hole 46 of the lid 33 through the
insulating gasket 39 by caulking. Further, the rectangular
insulating plate 40, which is placed on the bottom face of the lid
33, and the rectangular positive electrode lead 43, which is placed
on the undersurface of the insulating plate 40, are fixed on the
axis 34b of the positive electrode terminal 34 by caulking. When
the positive electrode of the electrode group 32 has such a
structure, it is electrically connected to the positive electrode
terminal 34 through the positive electrode tab 44 and the positive
electrode lead 43.
[0140] As shown in FIGS. 13B and 13C, the negative electrode
terminal 35 has a rivet-like shape. Specifically, it has a head 35a
and an axis 35b which extends from the head 35a. The negative
electrode terminal 35 is fixed in the through hole 38 of the lid 33
through the insulating gasket 39 by caulking. Further, the
rectangular insulating plate 40, which is placed on the bottom face
of the lid 33, and the rectangular negative electrode lead 41,
which is placed on the undersurface of the insulating plate 40, are
fixed on the axis 35b of the negative electrode terminal 35 by
caulking. When the negative electrode of the electrode group 32 has
such a structure, the electrode is electrically connected to the
negative electrode terminal 35 through the negative electrode tab
42 and the negative electrode lead 41.
[0141] As shown in FIG. 13A, when the positive and negative
electrode terminals 34 and 35 are fixed on the lid 33 by caulking
in this embodiment, the bottom 36 of the lid 33 is deformed and
protrusions 47' are generated at positions corresponding to the
through holes 46 and 38. However, protrusion 47 are made in
anticipation of the deformation volumes of these protrusions 47',
and therefore, the protrusions 47' fall within a range of the
depressions 47. As a result, when the bottom 36 of the lid 33 is
inserted into an opening part of the container 31, a gap generated
between the bottom 36 of the lid 33 and a side wall around the
opening part of the container 31 can be reduced. In addition, the
flange 37 can cover the opening part of the container 31 because
the lid 33 has the flange 37. Thus, the gap generated between the
bottom 36 of the lid 33 and the side wall around the opening part
of the container 31 is not exposed to the outside. As a result,
welding defects resulting from the gap between the lid 33 and the
container 31 can be further reduced. The deformation of the lid 33
can be reduced because the deformation of the bottom 36 of the lid
33 due to the caulking occurs in the depressions 47, and therefore
variation per product in a size such as a total height of a battery
or a height of a positive or negative electrode terminal can be
further reduced. In order to assemble an assembled battery from the
angular batteries, laser welding of bus bars to the positive and
negative electrode terminals 34 and 35 equipped on the lid 33 is
necessary. According to the fifth embodiment, the variation in the
height of the battery can be reduced, and thus a yield of the laser
welding can be improved in the production of the assembled
battery.
[0142] The lids used in the fourth and fifth embodiments have a
shape in which all parts disposed above the bottom are the flange
part, but they are not limited to this shape, and, for example, it
is possible to make a stair part having a smaller area than that of
the flange at the top surface of the flange.
[0143] According to the embodiment described above, the angular
battery having the lid with the electrode terminals attached
thereto by caulking can be provided and welding yields can be
improved in the production method thereof.
Positive Electrode
[0144] The positive electrode used in the first to fifth
embodiments will be explained. The positive electrode can be
formed, for example, by coating a current collector with slurry
containing a positive electrode active material. The positive
electrode active material is not particularly limited, and oxides,
sulfides or polymers capable of occluding and releasing lithium can
be used. Examples of the preferable active material include lithium
manganese complex oxides, lithium nickel complex oxides, lithium
cobalt complex oxides, and lithium iron phosphate, which can
provide a high positive electrode potential. The current collector
can be formed, for example, from an aluminum foil or an aluminum
alloy foil.
Negative Electrode
[0145] The negative electrode used in the first to fifth
embodiments will be explained. The negative electrode can be
formed, for example, by coating a current collector with slurry
containing a negative electrode active material. The negative
electrode active material is not particularly limited, and metal
oxides, metal sulfides, metal nitrides, alloy or carbon capable of
occluding and releasing lithium can be used. Materials having an
occlusion and release potential of lithium ion of 0.4 V or more
noble to a metal lithium potential are preferably used. The
negative electrode active material having such an occlusion and
release potential of lithium ion can inhibit an alloy reaction of
the aluminum or aluminum alloy with the lithium. Therefore, it is
possible to use aluminum or aluminum alloy for forming the negative
electrode current collector and related parts of the negative
electrode. Examples of such a negative electrode active material
include titanium oxides, lithium titanium oxides, tungsten oxides,
amorphous tin oxides, tin silicon oxides, and silicon oxides.
Lithium titanium complex oxides are particularly preferable. The
current collector can be formed, for example, from an aluminum foil
or an aluminum alloy foil.
Separator
[0146] The separator used in the first to fifth embodiments will be
explained. As the separator, for example, microporous films, woven
fabrics, non-woven fabrics or laminates thereof may be used. The
laminate may be formed from the same material or different
materials. Examples of the material forming the separator include
polyethylene, polypropylene, ethylene-propylene copolymers, and
ethylene-butene copolymers.
Electrolyte Solution
[0147] The electrolyte solution used in the first to fifth
embodiments will be explained. A nonaqueous electrolyte solution
may be used as the electrolyte solution. The nonaqueous electrolyte
solution can be prepared by dissolving an electrolyte such as a
lithium salt in a nonaqueous solvent. Examples of the nonaqueous
solvent include ethylene carbonate (EC), propylene carbonate (PC),
butylene carbonate (BC), dimethyl carbonate (DMC), diethyl
carbonate (DEC), ethylmethyl carbonate (EMC), .gamma.-butyrolactone
(.gamma.-BL), sulfolane, acetonitrile, 1,2-dimethoxyethane,
1,3-dimethoxypropane, dimethyl ether, tetrahydrofuran (THF) and
2-methyltetrahydrofuran. The nonaqueous solvent may be used alone
or as a mixture of two or more kinds. Examples of the electrolyte
include lithium salts such as lithium perchlorate (LiClO.sub.4),
lithium hexafluorophosphate (LiPF.sub.6), lithium tetrafluoroborate
(LiBF.sub.4), lithium arsenic hexafluoride (LiAsF.sub.6), and
lithium trifluoromethasulfonate (LiCF.sub.3SO.sub.3). The
electrolyte may be used alone or as a mixture of two or more kinds.
The amount of the electrolyte dissolved in the nonaqueous solvent
is preferably within a range of 0.2 mol/L to 3 mol/L.
EXAMPLE
<Experiment 1>
[0148] Examples of the embodiment will be explained below. A
specimen for test in which a lead fixed on a lid was connected to a
backup lead which sandwiched a current collector tab extended from
an electrode group was made. In order to examine whether or not a
safety valve was broken by applying vibration to the lid, the lead
was joined to the backup lead by ultrasonic joining.
Specimen 1
[0149] A lead used in the battery of the first embodiment and
having a shape shown in FIG. 2 was made using aluminum. Sizes of
the lead were: X1 was 3.5 mm, Y1 was 25.5 mm, Z1 was 5.5 mm, W1 was
13.5 mm, R1 was 7.0 mm, M1 was 0.8 mm, and a thickness was 0.8 mm.
X1/Y1 was 0.137.
[0150] The lid junctional part of the lead was fixed to the lid by
caulking output terminals. Then a current collector tab junctional
part of the lead was joined to each backup lead which sandwiched a
current collector tab of a positive or negative electrode by
ultrasonic joining to make a sample.
[0151] MODEL 2000 manufactured by Branson was used as an ultrasonic
joining machine. A joined sample was A1050-H 0.8 mmt, and its horn
shape was 2 peaks (a pitch of 3.6 mm). A pressure of 450 N was
applied, amplitude was 80%, and a test time (joining time) was 0.5
seconds.
[0152] As results of the ultrasonic joining, there was no breakage
of a safety valve in 100 samples tested.
[0153] In addition, resistance values between a center of the lid
junctional part of the lead and a center of the current collector
tab junctional part were measured, and an average value thereof was
calculated. A value of 0.13 m.OMEGA. was obtained. Test conditions
and measurement results are shown in Table 1.
Specimen 2
[0154] Tests were performed in the same manner as in those for the
specimen 1 except that a lead having X1 of 5.0 mm and X1/Y1 of
0.196 was used. As results of ultrasonic joining, breakage of a
safety valve occurred in two samples of 100 samples tested. The
lead had a resistance value of 0.12 m.OMEGA.. Test conditions and
measurement results are shown in Table 1.
Specimen 3
[0155] Tests were performed in the same manner as in those for the
specimen 1 except that a lead having X1 of 2.0 mm and X1/Y1 of
0.078 was used. As for the specimen 3, tests of 100 samples were
scheduled to be performed, but leads were broken in all 30 samples
upon ultrasonic joining since the test had started, and therefore,
the experiment was stopped when the 30 samples were tested. The
lead had a resistance value of 0.14 m.OMEGA.. Test conditions and
measurement results are shown in Table 1.
Comparative Example 1
[0156] In Comparative Example 1, a lead having a shape shown in
FIG. 14 was used. This lead had a lid junctional part 103 (a), a
current collector tab junctional part 103 (b), and a linkage 103
(c) which linked the lid junctional part 103 (a) to the current
collector tab junctional part 103 (b), and had a shape which was
bent almost at a right angle along a side separating the linkage
103 (c) from the lid junctional part 103 (a).
[0157] A length A1 of the lid junctional part 103 (a) in a longer
direction was 20.5 mm, a length A2 of the lid junctional part 103
(a) crossing at a right angle to the longer direction was 7.0 mm, a
length B1 of the current collector tab junctional part 103 (b) in a
longer direction was 25.5 mm, a length B2 of the current collector
tab junctional part 103 (b) crossing at a right angle to the longer
direction was 5.5 mm, a length C1 of the linkage 103 (c) in a
longer direction was 7.5 mm, a length C2 of the linkage 103 (c)
crossing at a right angle to the longer direction was 0.9 mm, and a
thickness was 0.8 mm. C1/B1 was 0.57. Tests were performed in the
same manner as in those for the specimen 1 except that the lead
having the shape described above was used.
[0158] In Comparative Example 1, breakage of a safety valve
occurred in 78 samples among 100 samples tested. The lead had a
resistance value of 0.11 m.OMEGA.. Test conditions and measurement
results are shown in Table 1.
TABLE-US-00001 TABLE 1 Pressure Joining X1/Y1 applied Amplitude
time Resistance Results Specimen 1 0.137 450 N 80% 0.5 seconds 0.13
m.OMEGA. 0/100 pcs occurrence of breakage Specimen 2 0.196 450 N
80% 0.5 seconds 0.12 m.OMEGA. 2/100 pcs occurrence of breakage
Specimen 3 0.078 450 N 80% 0.5 seconds 0.14 m.OMEGA. Lead was
broken upon the ultrasonic joining (impossible to test) Comparative
-- 450 N 80% 0.5 seconds 0.11 m.OMEGA. 78/100 pcs occurrence of
breakage Example 1
[0159] Table 1 shows that the breakage in the specimen 1 and 2
using the lead having X1/Y1 within a range of 0.12 or more and 0.2
or less occurred less frequently than in Comparative Example 1, and
that the vibration was hardly transmitted to the lid. In addition,
it was shown that the leads in the specimens 1 and 2 had a
resistance value which was almost the same as that of the lead
having no vibration absorber part in Comparative Example 1, and a
battery performance was not influenced. On the other hand, due to
the fact that the lead in the specimen 3 was broken upon the
ultrasonic joining, the results showed that the lead having X1/Y1
of less than 0.12 had a low strength.
<Experiment 2>
[0160] Tests were performed in different ultrasonic joining
conditions.
Specimen 4
[0161] Samples were made using the same lead as that in the
specimen 1 except that a pressure of 1000 N was applied upon the
ultrasonic joining, an amplitude was 90%, and a testing time
(joining time) was one second. As results of the ultrasonic
joining, breakage of a safety valve occurred in three samples among
100 samples tested. The lead had a resistance value of 0.13
m.OMEGA.. Test conditions and measurement results are shown in
Table 2.
Specimen 5
[0162] A lead used in the battery of the second embodiment and
having a shape shown in FIG. 4 was made using aluminum. Sizes of
the lead were: Y2 was 5.5 mm, Z2 was 21 mm, W2 was 13.5 mm, R2 was
8.0 mm, Q2 was 8.5 mm, and a thickness was 0.8 mm. Ultrasonic
joining conditions were the same as those for the specimen 4.
[0163] As results of ultrasonic joining, there was no breakage of a
safety valve in 100 samples tested. The lead had a resistance value
of 0.15 m.OMEGA.. Test conditions and measurement results are shown
in Table 2.
Specimen 6
[0164] A lead used in the battery of the third embodiment and
having a shape shown in FIG. 9 was made using aluminum. Sizes of
the lead were: X2 was 4.5 mm, and M2 was 5.8 mm. X2/Y2 was 0.818.
Other sizes were the same as those of the lead used in the specimen
5. Ultrasonic joining conditions were the same as those in the
specimen 4.
[0165] As results of ultrasonic joining, there was no breakage of a
safety valve in 100 samples tested. The lead had a resistance value
of 0.15 m.OMEGA.. Test conditions and measurement results are shown
in Table 2.
Specimen 7
[0166] A lead having the same sizes as those of the lead in the
specimen 6 except that X2 was 3.0 mm and X2/Y2 was 0.545 was used.
Ultrasonic joining conditions were the same as those in the
specimen 4.
[0167] As results of ultrasonic joining, there was no breakage of a
safety valve in 100 samples tested. The lead had a resistance value
of 0.16 m.OMEGA.. Test conditions and measurement results are shown
in Table 2.
Specimen 8
[0168] A lead having the same sizes as those of the lead in the
specimen 6 except that X2 was 2.0 mm and X2/Y2 was 0.364 was used.
Ultrasonic joining conditions were the same as in the specimen
4.
[0169] As for the specimen 8, tests of 100 samples were scheduled
to be performed, but leads were broken in all 30 samples upon
ultrasonic joining since the test had started, and therefore, the
experiment was stopped when the 30 samples were tested. The lead
had a resistance value of 0.17 m.OMEGA.. Test conditions and
measurement results are shown in Table 2.
Comparative Example 2
[0170] Tests were performed in the same manner as those for the
specimen 4 except that a lead which was the same as that in
Comparative Example 1 was used. In Comparative Example 2, breakage
of a safety valve occurred in all 100 samples tested. The lead had
a resistance value of 0.11 m.OMEGA.. Test conditions and
measurement results are shown in Table 2.
TABLE-US-00002 TABLE 2 Pressure Joining X1/Y1 X2/Y2 applied
Amplitude time Resistance Results Specimen 4 0.137 -- 1,000 N 90% 1
seconds 0.13 m.OMEGA. 3/100 pcs occurrence of breakage Specimen 5
-- -- 1,000 N 90% 1 seconds 0.15 m.OMEGA. 0/100 pcs occurrence of
breakage Specimen 6 -- 0.818 1,000 N 90% 1 seconds 0.15 m.OMEGA.
0/100 pcs occurrence of breakage Specimen 7 -- 0.545 1,000 N 90% 1
seconds 0.16 m.OMEGA. 0/100 pcs occurrence of breakage Specimen 8
-- 0.364 1,000 N 90% 1 seconds 0.17 m.OMEGA. Lead was broken upon
the ultrasonic joining (impossible to test) Comparative -- -- 1,000
N 90% 1 seconds 0.11 m.OMEGA. 100/100 pcs occurrence of breakage
Example 2
[0171] It was shown that the breakage occurred less frequently in
the specimen 4 than in Comparative Example 2, and even if the
ultrasonic joining was performed at a high pressure and high
amplitude for a long period of time, transmission of the vibration
to the lid could be inhibited.
[0172] In addition, it was shown that in the specimens 5 to 7 using
the lead having X2/Y2 of 0.5 or more, no breakage occurred and even
if the ultrasonic joining was performed at a high pressure and high
amplitude for a long period of time, transmission of the vibration
to the lid could be inhibited.
[0173] On the other hand, due to the fact that the lead in the
specimen 8 was broken upon the ultrasonic joining, it was shown
that the lead having an X2/Y2 of less than 0.5 had a low
strength.
<Experiment 3>
[0174] Samples were made in the same flow, using the same leads as
in the specimen 1, the specimen 6 and Comparative Example 1, and
whether a safety valve was broken or not upon the manufacturing
flow was confirmed. Ultrasonic joining conditions were: a pressure
of 535 N was applied, amplitude was 36 .mu.m, and a joining time
was 0.8 seconds at a time. The results are shown in Table 3.
TABLE-US-00003 TABLE 3 Pressure The number applied Amplitude Test
time of samples Results Specimen 1 535 N 36 .mu.m 0.8 seconds 500
pcs No safety valve was broken at a time by ultrasonic joining
Specimen 6 535 N 36 .mu.m 0.8 seconds 500 pcs No safety valve was
broken at a time by ultrasonic joining Comparative 535 N 36 .mu.m
0.8 seconds 300 pcs Safety valve was broken at Example 1 at a time
102 pcs by ultrasonic joining
[0175] As shown in Table 3, in the samples using the leads used in
the specimens 1 and 6, there was no breakage of the safety valve in
all 500 samples. On the other hand, in the samples using the lead
used in Comparative Example 1, breakage occurred of a safety valve
in 102 samples among 300 samples.
<Experiment 4>
Example 1
[0176] Twenty angular nonaqueous electrolyte batteries were
produced in the same manner as in the fourth embodiment. The
angular nonaqueous electrolyte battery had the same structure as
that shown in FIG. 10 except that a positive electrode terminal 34
was fixed to a lid 33 by caulking shown in FIG. 11. A plate formed
from aluminum alloy of JIS-A-3003 having a plate thickness of 0.5
mm was used for a container 31. A lid formed from aluminum alloy of
JIS-A-3003, having a thickness of 0.2 mm of flange 37, and a total
thickness of 1.1 mm was used for the lid 33.
Example 2
[0177] Twenty angular nonaqueous electrolyte batteries were
produced in the same manner as those in Example 1 except that the
thickness of the flange 37 was changed to 0.4 mm.
Comparative Example 3
[0178] A lid 33 on which a flange 37 was not provided, as shown in
FIG. 15, was used. When positive and negative electrode terminals
34 and 35 were fixed in through holes 46 and 38 in this lid 33 by
caulking, respectively, parts corresponding to the through holes 46
and 38 on both sides of the lid 33 in a long side direction were
deformed outward, as shown in FIG. 16. As shown in FIG. 17A, the
lid 33 whose both sides were deformed was fitted into an opening
part of a container 31. After that, as shown in FIG. 17B, laser
seam welding was performed by irradiating a laser beam parallel to
a surface at which the side of the lid 33 was overlaid on the
opening part of the container 31 (i.e., a side wall inner surface)
from a tool for welding 45.
[0179] Twenty angular nonaqueous electrolyte batteries were
produced in the same manner as those in Example 1 except for the
procedures described above. A cross-sectional view of the angular
battery of Comparative Example 3, which was cut along a short side
direction, is shown in FIG. 17C.
[0180] As for the batteries of Examples 1 and 2 and Comparative
Example 3, an average height difference (population parameter n=20)
in some spots on a top surface of the lid 33 after laser welding
was measured. The spots where the height was measured were three
spots: a center of the lid 33 (for example, a spot C shown in FIG.
17A), one end of the lid 33 in a long side direction (for example,
a spot A shown in FIG. 17A), and the other end thereof (for example
a spot B shown in FIG. 17A). The height at the spot A and the
height at the spot B were compared with the height at the center C
of the lid 33 which was set as a standard. When the height at the
spot A or the spot B was lower than the standard, the difference
was shown as a negative value in Table 4, and when the height
thereof was higher than the standard, the difference was shown as a
positive value in Table 4.
TABLE-US-00004 TABLE 4 Center of lid Spot A C (standard) Spot B
Comparative No flange -0.08 mm 0.00 mm -0.11 mm Example 3 Example 1
Flange 0.2 mm 0.00 mm 0.00 mm +0.01 mm Example 2 Flange 0.4 mm 0.00
mm 0.00 mm 0.00 mm
[0181] As is apparent from Table 4, in Comparative Example 3 in
which the lid having no flange was used, the heights at both ends A
and B were lower by about 0.1 mm than that at the center C of the
lid which was set as the standard, and therefore the center C was
convexly formed. Additionally, as shown in FIG. 17A, there were
gaps between the lid 33 and the container 31 because the shape of
the side of the lid 33 did not fit with the shape of the opening
part of the container 31.
[0182] On the contrary, in Examples 1 and 2 in which the lids
having the flange were used, the heights at the spots A and B were
within a range of .+-.0.01 mm in both Example 1 in which the flange
thickness was 0.2 mm and Example 2 in which the thickness was 0.4
mm, which were excellent.
<Experiment 5>
Comparative Example 4
[0183] As shown in FIG. 18, a lid 33 in which four parts 48
corresponding to through holes 46 and 38 on long sides became
dented inward, and which had no flange 37 was used. When positive
and negative electrode terminals 34 and 35 were fixed in through
holes 46 and 38 of this lid 33 by caulking, respectively, parts
corresponding to the through holes 46 and 38 on both sides of the
lid 33 in a long side direction were slightly curved outward, as
shown in FIG. 19. As shown in FIG. 20A, the lid 33 whose sides were
deformed was fitted into an opening part of a container 31. After
that, as shown in FIG. 20B, laser seam welding was performed by
irradiating a laser beam parallel to a surface at which the side
face of the lid 33 was overlaid on the opening part of the
container 31 (i.e., a side wall inner surface) from a tool for
welding 45.
[0184] Angular nonaqueous electrolyte batteries were produced in
the same manner as those in Example 1 except for the procedures
described above. A cross-sectional view of the angular battery of
Comparative Example 4, which was cut along a short side direction,
is shown in FIG. 20C.
[0185] As shown in FIG. 20A, welding defects occurred because there
were gaps between a side wall around an opening part of the
container 31 and the sides of the lid 33.
[0186] While certain embodiments have been described, these
embodiments have been presented by way of example only, and are not
intended to limit the scope of the inventions. Indeed, the novel
embodiments described herein may be embodied in a variety of other
forms; furthermore, various omissions, substitutions and changes in
the form of the embodiments described herein may be made without
departing from the spirit of the inventions. The accompanying
claims and their equivalents are intended to cover such forms or
modifications as would fall within the scope and spirit of the
inventions.
* * * * *