U.S. patent application number 14/236209 was filed with the patent office on 2014-07-10 for electrode plate, layered electrode group, and battery.
This patent application is currently assigned to GS YUASA INTERNATIONAL LTD.. The applicant listed for this patent is Tadashi Kakeya, Manabu Kanemoto, Mitsuhiro Kodama. Invention is credited to Tadashi Kakeya, Manabu Kanemoto, Mitsuhiro Kodama.
Application Number | 20140193701 14/236209 |
Document ID | / |
Family ID | 47629091 |
Filed Date | 2014-07-10 |
United States Patent
Application |
20140193701 |
Kind Code |
A1 |
Kanemoto; Manabu ; et
al. |
July 10, 2014 |
ELECTRODE PLATE, LAYERED ELECTRODE GROUP, AND BATTERY
Abstract
A layered electrode group according to the present invention
includes a positive electrode plate, a negative electrode plate,
and a separator. The positive electrode plate is formed into a
substantial U-shape by disposing two active material retaining
portions retaining the positive active material opposite to each
other. The negative electrode plate is formed into a substantial
U-shape by disposing two active material retaining portions
retaining the negative active material opposite to each other. The
positive electrode plate and the negative electrode plate are
layered such that at least one active material retaining portion at
the positive electrode plate is sandwiched between two active
material retaining portions at the negative electrode plate.
Inventors: |
Kanemoto; Manabu; (Kyoto,
JP) ; Kakeya; Tadashi; (Kyoto, JP) ; Kodama;
Mitsuhiro; (Kyoto, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kanemoto; Manabu
Kakeya; Tadashi
Kodama; Mitsuhiro |
Kyoto
Kyoto
Kyoto |
|
JP
JP
JP |
|
|
Assignee: |
GS YUASA INTERNATIONAL LTD.
Kyoto
JP
|
Family ID: |
47629091 |
Appl. No.: |
14/236209 |
Filed: |
July 20, 2012 |
PCT Filed: |
July 20, 2012 |
PCT NO: |
PCT/JP2012/068523 |
371 Date: |
January 30, 2014 |
Current U.S.
Class: |
429/166 ;
29/623.1; 429/211 |
Current CPC
Class: |
H01M 2/18 20130101; H01M
6/02 20130101; H01M 2/0227 20130101; H01M 2/30 20130101; H01M 4/80
20130101; Y02E 60/10 20130101; H01M 2/266 20130101; H01M 10/0422
20130101; H01M 10/0459 20130101; H01M 4/78 20130101; H01M 10/045
20130101; H01M 10/0431 20130101; H01M 2/022 20130101; Y10T 29/49108
20150115 |
Class at
Publication: |
429/166 ;
429/211; 29/623.1 |
International
Class: |
H01M 2/02 20060101
H01M002/02 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 2, 2011 |
JP |
2011-169575 |
Aug 2, 2011 |
JP |
2011-169672 |
Claims
1. A layered electrode group comprising: a positive electrode plate
retaining a positive active material in a positive electrode
current collector; a negative electrode plate retaining a negative
active material in a negative electrode current collector; and a
separator interposed between the positive electrode plate and the
negative electrode plate, wherein the positive electrode plate is
formed into a substantial U-shape by disposing two active material
retaining portions retaining the positive active material opposite
to each other, the negative electrode plate is formed into a
substantial U-shape by disposing two active material retaining
portions retaining the negative active material opposite to each
other, and the positive electrode plate and the negative electrode
plate are layered such that at least one active material retaining
portion at either one of the positive electrode plate and the
negative electrode plate is sandwiched between two active material
retaining portions at the other one of the positive electrode plate
and the negative electrode plate.
2. The layered electrode group according to claim 1, wherein a
folded portion formed between the two active material retaining
portions at the positive electrode plate and a folded portion
formed between the two active material retaining portions at the
negative electrode plate face each other in stacking.
3. The layered electrode group according to claim 1, wherein the
positive electrode plates and the negative electrode plates are
layered such that one active material retaining portion at each of
the two positive electrode plates adjacent to each other is
sandwiched between the two active material retaining portions
facing each other at one of the negative electrode plates.
4. The layered electrode group according to claim 1, wherein the
positive electrode plates and the negative electrode plates are
layered such that one active material retaining portion at each of
the two negative electrode plates adjacent to each other is
sandwiched between the two active material retaining portions
facing each other at one of the positive electrode plates.
5. The layered electrode group according to claim 1, wherein the
separator is folded in half to sandwich both surfaces of the
positive electrode plate or the negative electrode plate in a state
in which the positive electrode plate or the negative electrode
plate is developed.
6. The layered electrode group according to claim 1, wherein the
positive electrode plate or the negative electrode plate has a
current collecting terminal extending from a folded portion formed
between the two active material retaining portions outward along a
folding line of the folded portion.
7. The layered electrode group according to claim 6, wherein in the
positive electrode plate or the negative electrode plate having the
current collecting terminal extending from the folded portion, the
separator is disposed to cover the positive electrode plate or the
negative electrode plate, and the separator having a cutout that is
formed at a portion corresponding to the current collecting
terminal extending from the folded portion.
8. The layered electrode group according to claim 1, wherein at
least one active material retaining portion at one of the positive
electrode plate and the negative electrode plate is sandwiched by
the other one of the positive electrode plate and the negative
electrode plate, the other one of the positive electrode plate and
the negative electrode plate includes an active material
non-retaining portion, which is not coated or filled with an active
material, and active material retaining portions, which are formed
on both sides while sandwiching the active material non-retaining
portion and are coated or filled with an active material, the
current collector is folded at the active material non-retaining
portion such that the active material retaining portions on both
sides face each other, and a part of the active material
non-retaining portion at the other one of the positive electrode
plate and the negative electrode plate is folded outward to form
the current collecting terminal.
9. A battery comprising the layered electrode group according to
claim 1.
10. A cylindrical battery comprising the layered electrode group
according to claim 1 contained in a cylindrical battery case.
11. A manufacturing method for the layered electrode group
according to claim 1, the method comprising: a negative electrode
plate folding step of folding a negative electrode plate in a
developed state in a substantial U-shape to sandwich two active
material retaining portions disposed at a positive electrode plate
in a developed state between the folded negative electrode plate;
and a positive electrode plate folding step of folding the positive
electrode plate whose two active material retaining portions are
sandwiched in the folded negative electrode plate in a substantial
U-shape.
12. The manufacturing method for the layered electrode group
according to claim 11, further comprising a separator containing
step of surrounding the positive electrode plate with a separator
to sandwich both surfaces of the positive electrode plate in the
developed state before the negative electrode plate folding
step.
13. An electrode plate formed into a substantial U-shape, in which
two active material retaining portions retaining an active material
in a current collector are disposed opposite to each other, wherein
a current collecting terminal extends along a folding line of a
folded portion formed between the two active material retaining
portions from the folded portion.
14. The electrode plate according to claim 13, wherein the
electrode plate is sandwiched at both surfaces thereof by a
separator folded in half in a developed state.
15. A layered electrode group comprising: the first electrode plate
according to claim 13; and a second electrode plate configured to
have a different polarity from that of a first electrode plate, in
which a current collector is coated or filled with an active
material, wherein the second electrode plate includes a linear
non-coated part that is not coated or filled with an active
material and coated parts that are formed on both sides while
sandwiching the non-coated part therebetween and are coated or
filled with the active material, the current collector is folded at
the non-coated part such that the coated parts on both sides face
each other, and further, a part of the non-coated part is folded
outward, thus forming a current collecting terminal, and the first
electrode plate is sandwiched between the coated parts on both
sides of the second electrode plate.
16. The electrode plate according to claim 13, configured to allow
the current collector, which is substantially rectangular, to
retain the active material, wherein the electrode plate comprises
an active material non-retaining portion that is substantially
linearly formed and does not retain any active material, the active
material retaining portions that are formed on both sides while
sandwiching the active material non-retaining portion therebetween
and retain the active material, and the current collecting terminal
disposed at the active material non-retaining portion, the current
collector is folded in a substantial U-shape at the active material
non-retaining portion such that the active material retaining
portions on both sides face each other, and the current collecting
terminal extends outward along the folding line of the folded
portion formed between the two active material retaining portions
from the folded portion.
17. The electrode plate according to claim 16, wherein the current
collector is made of a three-dimensional metallic porous
substrate.
18. An electrode plate comprising: two active material retaining
plates that retain an active material in a current collector; and a
current collecting terminal for connecting the two active material
retaining plates to each other, wherein the current collecting
terminal is folded in a substantial U-shape such that the two
active material retaining plates face each other, and the current
collecting terminal has an extension portion extending outward
along a folding line of a folded portion.
19. The electrode plate according to claim 18, wherein the current
collecting terminal is a flat plate formed into a T-shape, as
viewed on a plane.
20. The electrode plate according to claim 14, wherein the folded
portion of the separator is located on a side edge other than a
side edge on which a current collecting terminal at the electrode
plate extends outward.
Description
TECHNICAL FIELD
[0001] The present invention relates to a layered electrode group,
a manufacturing method therefor, and a battery.
BACKGROUND ART
[0002] Among conventional cylindrical batteries, there is a battery
containing a columnar electrode group obtained by winding belt-like
positive and negative electrode plates in a spiral manner via a
belt-like separator and contained in a cylindrical battery case, as
disclosed in Patent Document 1.
[0003] However, a winding misalignment may occur between the
positive and negative electrode plates during a winding process in
the battery in which the belt-like positive and negative electrode
plates and the separator are wound in the spiral manner. Then,
there arises a problem that a desired battery capacity may not be
achieved in the cylindrical battery or that an internal
short-circuit may be caused.
PRIOR ART DOCUMENTS
Patent Documents
[0004] Patent Document 1: JP-A-11-185767
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0005] In view of the above, in order to solve the winding
misalignment and various kinds of problems associated with the
winding misalignment, the inventors of the present application have
conceived containing a layered electrode group in a cylindrical
battery.
[0006] However, in the case where a layered electrode group is
contained in a battery case, current collecting terminals of a
plurality of positive electrode plates are connected to a common
current collecting plate and the current collecting plate is welded
to a lid of the battery case, or the current collecting terminal of
each of the positive electrode plates is welded to the lid, thereby
causing variations of current collecting efficiency in each of the
positive electrode plates. Moreover, work for welding the current
collecting terminal of each of the positive electrode plates to a
current collector or a battery case becomes complicated.
[0007] In view of the above, the present invention has been
accomplished in order to solve the above-described problems.
Therefore, main required problems to be solved are to commonly use
a current collecting terminal at two active material retaining
portions that retain an active material to prevent variations of
current collecting efficiency, and further, reduce the number of
current collecting terminals, thus not only simplifying a welding
work but also facilitating work for layering a plurality of
electrode plates.
Means for Solving the Problems
[0008] A layered electrode group according to the present invention
is featured by a layered electrode group comprising a positive
electrode plate retaining a positive active material in a positive
electrode current collector, a negative electrode plate retaining a
negative active material in a negative electrode current collector,
and a separator interposed between the positive electrode plate and
the negative electrode plate. The positive electrode plate is
formed into a substantial U-shape by disposing two active material
retaining portions retaining the positive active material opposite
to each other. The negative electrode plate is formed into a
substantial U-shape by disposing two active material retaining
portions retaining the negative active material opposite to each
other. The positive electrode plate and the negative electrode
plate are layered such that at least one active material retaining
portion at either one of the positive electrode plate and the
negative electrode plate is sandwiched between two active material
retaining portions at the other one of the positive electrode plate
and the negative electrode plate. Here, the substantial U-shape is
the concept encompassing a substantial V-shape, unless specifically
distinguished, in the following description.
[0009] With the above-described layered electrode group, each of
the positive electrode plate and the negative electrode plate is
formed into the substantial U-shape with the two active material
retaining portions facing each other. The common current collecting
terminal collects a current at the two active material retaining
portions, thus suppressing variations of current collecting
efficiency to enhance the current collecting efficiency. Moreover,
the current collecting terminal can be used commonly to the two
active material retaining portions, thereby reducing the number of
current collecting terminals to be welded to simplify a welding
work. Additionally, the positive electrode plate and the negative
electrode plate formed into the substantial U-shape are layered to
be interlaced each other, thus remarkably simplifying work for
layering the plurality of electrode plates, and further, making it
difficult to untie the layered electrode group after the
stacking.
[0010] A specific stacking mode of the positive electrode plate and
the negative electrode plate is conceived such that a folded
portion formed between the two active material retaining portions
at the positive electrode plate and a folded portion formed between
the two active material retaining portions at the negative
electrode plate face each other in stacking. In this manner, the
folded portion of the positive electrode plate and the folded
portion of the negative electrode plate can be most separated from
each other. When the layered electrode group is contained inside
the battery case, works for welding the current collecting terminal
of the negative electrode plate to the bottom of the battery case
and welding the current collecting terminal of the positive
electrode plate to a battery lid can be facilitated.
[0011] It is desirable that the positive electrode plates and the
negative electrode plates should be layered such that one active
material retaining portion at each of the two positive electrode
plates adjacent to each other is sandwiched between the two active
material retaining portions facing each other at one of the
negative electrode plates. In this manner, the electrode plates are
layered such that one negative electrode plate sandwiches two
positive electrode plates, thus preventing any misalignment of the
adjacent positive electrode plates as much as possible.
[0012] In the same manner, it is desirable that the positive
electrode plates and the negative electrode plates should be
layered such that one active material retaining portion at each of
the two negative electrode plates adjacent to each other is
sandwiched between the two active material retaining portions
facing each other at one of the positive electrode plates. In this
manner, the electrode plates are layered such that one positive
electrode plate sandwiches two negative electrode plates, thus
preventing any misalignment of the adjacent negative electrode
plates as much as possible.
[0013] It is desirable that the separator should be folded in half
to sandwich both surfaces of the positive electrode plate or the
negative electrode plate in a state in which the positive electrode
plate or the negative electrode plate is developed. In this manner,
the positive electrode plate or the negative electrode plate in a
developed state is contained in the separator, before the positive
electrode plate or the negative electrode plate contained in the
separator is folded, so that the separator can be securely
interposed between the positive electrode plate and the negative
electrode plate. Consequently, the arrangement of the plate that is
not contained can be designed without any restriction by the
separator, and further, a fear of a short-circuit is reduced in a
manufacturing process.
[0014] It is desirable that the positive electrode plate or the
negative electrode plate should have a current collecting terminal
extending from a folded portion formed between the two active
material retaining portions outward along a folding line of the
folded portion. In this manner, the current collecting terminal is
provided to extend outward along the folding line at the folded
portion (that is, outward on one side in a width direction
perpendicular to the direction in which the two active material
retaining portions face each other). Therefore, in the case where
the electrode plate in the developed state is contained to be
sandwiched in the separator folded in half, the folded portion of
the separator is located on a side edge other than a side edge on
which the current collecting terminal extends outward, so that the
current collecting terminal does not interfere a containing work in
the separator.
[0015] It is desirable that in the positive electrode plate or the
negative electrode plate having the current collecting terminal
extending from the folded portion, the separator should be disposed
to cover the positive electrode plate or the negative electrode
plate, the separator having a cutout that is formed at a portion
corresponding to the current collecting terminal extending from the
folded portion. In this manner, it is possible to prevent the
separator from curling up according to the deformation of the
current collecting terminal when the current collecting terminal is
folded.
[0016] It is desirable that the other one of the electrode plates
sandwiching the one electrode plate should include an active
material non-retaining portion which is not coated with an active
material, and active material retaining portions which are formed
on both sides while sandwiching the active material non-retaining
portion and are coated with an active material, wherein the current
collector is folded at the active material non-retaining portion
such that the active material retaining portions on both sides face
each other, and further, a part of the active material
non-retaining portion at the other one of the electrode plates is
folded outward, to form the current collecting terminal. In this
manner, a part of the non-coated portion is folded to form the
current collecting terminal, thereby dispensing with forming a
current collecting terminal at the coated portion or welding and
connecting a current collecting terminal to the coated portion. In
addition, the terminal can be formed at the end of the electrode
group, and therefore, the electrode group can be readily welded or
brought into contact with the battery case.
[0017] It is desirable that the electrode group of a layered
structure configured by using the electrode plate according to the
present invention should be configured as a cylindrical battery
contained in a cylindrical battery case. In the electrode group
wound in a spiral manner in the related art, the positive electrode
plate and the negative electrode plate are accidentally misaligned
during winding, thereby raising such problems that a desired
battery capacity cannot be obtained in the cylindrical battery or
an internal short-circuit occurs. However, the electrode group
having the layered structure is contained inside the cylindrical
battery case, like the present invention, thus solving winding
misalignment in the electrode group or various problems incidental
to the winding misalignment. Moreover, since the battery case is
formed into the cylindrical shape, it is resistant against an
increase in inside pressure. In addition, since the electrode group
formed into the substantially rectangular parallelepiped shape is
arranged in the cylindrical battery case, the use amount of a
substrate or a separator is reduced, thus enlarging a space defined
inside the battery case to not only prevent any increase in battery
inner pressure but also increase the amount of electrolyte solution
inside the cylindrical battery.
[0018] A manufacturing method for the layered electrode group
according to the present invention comprises: a negative electrode
plate folding step of folding a negative electrode plate in a
developed state in a substantial U-shape to sandwich two active
material retaining portions disposed on both sides of a positive
electrode plate in a developed state in the folded negative
electrode plate; and a positive electrode plate folding step of
folding the positive electrode plate in a substantial U-shape whose
two active material retaining portions are sandwiched in the folded
negative electrode plate.
[0019] With the above-described manufacturing method, after the
positive electrode plate and the negative electrode plate are
partly layered, the negative electrode plate can be folded in the
substantial U-shape at the side edge of the positive electrode
plate as a folding starting point, and therefore, the negative
electrode plate is readily folded in the substantial U-shape. In
contrast, when the positive electrode plate is folded in the
substantial U-shape, the positive electrode plate can be folded in
the substantial U-shape at the side edge of the negative electrode
plate as a folding starting point, and therefore, the positive
electrode plate is readily folded in the substantial U-shape.
[0020] It is desirable that the manufacturing method should further
comprise a separator containing step of surrounding the positive
electrode plate with a separator to sandwich both surfaces of the
positive electrode plate in the developed state before the negative
electrode plate folding step. In this manner, before the positive
electrode plate is folded in the substantial U-shape, the positive
electrode plate is surrounded by the separator, thereby
facilitating work for interposing the separator between the
positive electrode plate and the negative electrode plate that are
formed into the substantial U-shape.
[0021] An electrode plate according to the present invention is
featured by being formed into a substantial U-shape, in which two
active material retaining portions retaining an active material in
a current collector are disposed opposite to each other, wherein a
current collecting terminal extends outward along a folding line of
a folded portion formed between the two active material retaining
portions from the folded portion. As stated above, the substantial
U-shape is the concept encompassing a substantial V-shape, unless
specifically distinguished.
[0022] With the above-described electrode plate, the electrode
plate is formed into the substantial U-shape including the two
active material retaining portions and the folded portion, and
further, the current collecting terminal is disposed at the folded
portion. Consequently, the common current collecting terminal
collects a current at the two active material retaining portions,
thus suppressing variations of current collecting efficiency to
enhance the current collecting efficiency. Moreover, the current
collecting terminal can be used commonly to the two active material
retaining portions, thereby reducing the number of current
collecting terminals to be welded to simplify a welding work.
Moreover, the current collecting terminal is provided to extend
outward along the folding line at the folded portion (that is,
outward on one side in a width direction perpendicular to the
direction in which the two active material retaining portions face
each other). Therefore, in the case where the electrode plate in
the developed state is contained to be sandwiched in the separator
folded in half, the folded portion of the separator is located on a
side edge other than a side edge on which the current collecting
terminal extends outward, so that the current collecting terminal
does not interfere a containing work in the separator.
[0023] Moreover, the electrode plate according to the present
invention configured to allow a substantially rectangular current
collector to sandwich an active material is featured by comprising
an active material non-retaining portion that is substantially
linearly formed and does not retain any active material, active
material retaining portions that are formed on both sides while
sandwiching the active material non-retaining portion therebetween
and retain an active material, and a current collecting terminal
disposed at the active material non-retaining portion, wherein the
current collector is folded in a substantial U-shape at the active
material non-retaining portion in such a manner that the active
materials on both sides face each other, and the current collecting
terminal extends outward along a folding line of a folded portion
formed between the two active material retaining portions from the
folded portion.
[0024] With the above-described electrode plate, the electrode
plate is formed into the substantial U-shape comprising the two
active material retaining portions and the folded portion, and
further, the current collecting terminal is disposed at the folded
portion. Consequently, the common current collecting terminal
collects a current at the two active material retaining portions,
thus suppressing variations of current collecting efficiency to
enhance the current collecting efficiency. Moreover, the current
collecting terminal can be used commonly to the two active material
retaining portions, thereby reducing the number of current
collecting terminals to be welded to simplify a welding work.
Moreover, the current collecting terminal is provided to extend
outward along the folding line at the folded portion (that is,
outward on one side in a width direction perpendicular to the
direction in which the two active material retaining portions face
each other). Therefore, in the case where the electrode plate in
the developed state is contained to be sandwiched in the separator
folded in half, the folded portion of the separator is located on a
side edge other than a side edge on which the current collecting
terminal extends outward, so that the current collecting terminal
does not interfere a containing work in the separator. In addition,
the electrode plate can be constituted of the single current
collector, thus reducing the number of parts, and further, reducing
the number of man-hours required for welding the parts to each
other or the like.
[0025] It is desirable that the current collector should be made of
a three-dimensional metallic porous substrate. The use of the
three-dimensional metallic porous substrate facilitates the
manufacturing process more than in the case of the use of other
current collector substrate. Moreover, the use of the
three-dimensional metallic porous substrate is excellent in that
excellent current collecting characteristics can be achieved even
in the case of the use of an active material having a low
conductivity, and therefore, higher capacity of the electrode can
be achieved.
[0026] Here, the method for manufacturing the electrode plate with
the three-dimensional metallic porous substrate is conceived to
include: (1) an active material filling step of filling the entire
current collector substrate (i.e., a preform) made of a
three-dimensional metallic porous substrate with an active
material; (2) an electrode plate pressing step of pressing the
entire current collector substrate after this active material
filling step; (3) an active material removing step of removing the
active material by ultrasonic removal or the like such that an
active material non-retaining portion, which is linearly formed, is
formed at the center of the current collector substrate filled with
the active material; (4) a pressing step of pressing the active
material non-retaining portion in the current collector substrate
having the active material non-retaining portion formed thereat;
(5) a cutting step of cutting the current collector substrate
having the active material non-retaining portion pressed thereat in
a direction perpendicular to the active material non-retaining
portion; (6) a terminal welding step of welding a current collector
terminal to the active material non-retaining portion of the
current collector obtained by cutting; and (7) a folding step of
folding the current collector welded with the current collecting
terminal in a substantial U-shape at the active material
non-retaining portion. Alternatively, a method for manufacturing
the electrode plate with the three-dimensional metallic porous
substrate is conceived to include: (i) an active material filling
step of filling the entire current collector substrate (i.e., a
preform) made of a three-dimensional metallic porous substrate with
an active material; (ii) an electrode plate pressing step of
pressing the entire current collector substrate after this active
material filling step; (iii) a cutting step of cutting the pressed
current collector substrate in a developed shape of the electrode
plate; (iv) an active material removing step of removing the active
material by ultrasonic removal or the like such that an active
material non-retaining portion, which is linearly formed, is formed
at the center of the cut current collector substrate; (v) a
pressing step of pressing the active material non-retaining portion
in the current collector substrate having the active material
non-retaining portion formed thereat; (vi) a terminal welding step
of welding a current collector terminal to the pressed active
material non-retaining portion; and (vii) a folding step of folding
the current collector welded with the current collecting terminal
in a substantial U-shape at the active material non-retaining
portion. However, the active material once filled is removed in
either of the methods, thereby losing the active material.
[0027] In view of the above, it is preferable that the active
material should be filled only on both sides of the active material
non-retaining portion such that the active material non-retaining
portion that is linearly formed remains at the center of the
current collector substrate. Specifically a method is conceived to
include: (a) a pressing step of linearly pressing the center of the
current collector substrate (i.e., the preform) made of the
three-dimensional metallic porous substrate, the center serving as
the active material non-retaining portion; (b) an active material
filling step of filling a portion other than the pressed portion as
the active material non-retaining portion with the active material;
(c) an electrode plate pressing step of pressing the entire current
collector substrate after the active material filling step; (d) a
cutting step of cutting the current collector substrate having the
active material retaining portion and the active material
non-retaining portion formed thereat in a direction perpendicular
to the active material non-retaining portion; (e) a terminal
welding step of welding the current collecting terminal to the
active material non-retaining portion of the cut current collector
obtained; and (f) a folding step of folding the current collector
welded with the current collecting terminal in the substantial
U-shape at the active material non-retaining portion. With the
above-described method, it is possible to reduce the loss of the
active material, to reduce the manufacturing cost. Incidentally,
since the active material retaining portions are formed on both
sides while sandwiching the active material non-retaining portion
therebetween, the active material retaining portion and the active
material non-retaining portion are different in a percentage of
elongation, and therefore, they may be possibly broken on their
boundary. From the viewpoint of this, the manufacturing method (1)
to (7) or (i) to (vii) is preferred.
[0028] It is desirable that an electrode plate should comprise two
active material retaining plates that retain an active material in
a current collector and a current collecting terminal for
connecting the two active material retaining plates to each other,
wherein the two active material retaining plates are folded in a
substantial U-shape at the current collecting terminal to face each
other, and the current collecting terminal has an extension portion
extending outward along a folding line of a folded portion.
[0029] With the above-described electrode plate, since the
electrode plate is formed into the substantial U-shape by
connecting the two active material retaining plates via the current
collecting terminal, the common current collecting terminal
collects a current at the two active material retaining portions,
thus suppressing variations of current collecting efficiency to
enhance the current collecting efficiency. Moreover, the current
collecting terminal can be used commonly to the two active material
retaining portions, thereby reducing the number of current
collecting terminals to be welded to simplify a welding work.
Moreover, the current collecting terminal is provided with an
extension portion extending outward along the folding line at the
folded portion (that is, outward on one side in a width direction
perpendicular to the direction in which the two active material
retaining portions face each other). Therefore, in the case where
the electrode plate in the developed state is contained to be
sandwiched in the separator folded in half, the folded portion of
the separator is located on a side edge other than a side edge on
which the current collecting terminal extends outward, so that the
current collecting terminal does not interfere a containing work in
the separator.
[0030] Here, it is conceived that two strip-like terminals are
welded in a T-shape, thereby providing the current collecting
terminals. However, in order to reduce the number of parts, the
man-hours required for welding, or the like, it is desirable that
the current collecting terminal should be a flat plate formed into
a T'shape, as viewed on a plane.
[0031] It is desirable that the electrode plate should be
sandwiched at both surfaces thereof by the two-folded separator in
the developed state. At this time, particularly, the folded portion
of the separator should be desirably located on a side edge other
than a side edge on which the current collecting terminal at the
first electrode plate extends outward such that the arrangement of
the current collecting terminal of the first electrode plate can
prevent the current collecting terminal from interfering the
separator. In this manner, the folded portion of the separator is
located on the side other than the side on which the current
collecting terminal extends outward, and therefore, the
configuration in which the current collecting terminal extends
outward on one side in the width direction perpendicular to the
direction in which the two active material retaining portions face
each other can prevent the current collecting terminal from
interfering a containing work with the separator. Although an
envelope-like separator may be used, the two-folded separator can
more facilitate containing work of the electrode plate.
[0032] The electrode group, to which the electrode plate according
to the present invention is preferably applicable, has a layered
structure in which the electrode plates having different polarities
are interposed between the active material retaining portions on
both sides via the separator. In the electrode plate according to
the present invention, the active material retaining portions are
formed on both sides while sandwiching the active material
non-retaining portion that is linearly formed or the current
collecting terminal, and then, are folded at the active material
non-retaining portion or the current collecting terminal. Here, the
active material retaining portions that are folded to face each
other have the same polarity. With this configuration, the layered
electrode group can be configured only by sandwiching the electrode
plates having different polarities between the active material
retaining portions facing each other. Incidentally, a pocket type
electrode, an electrode made of a three-dimensional substrate such
as foamed nickel filled with an active material, and an electrode
having a two-dimensional substrate such as a porous steel plate
coated with the active material may be used as the electrode plate
having the different polarity. At this time, one negative electrode
plate and one positive electrode plate constitute the layered
electrode group.
[0033] An electrode plate preferably used in the relationship with
the first electrode plate comprising the electrode plate according
to the present invention desirably should include a second
electrode plate having a different polarity from that of the first
electrode plate and having a current collector coated with an
active material. The second electrode plate includes a linear
non-coated portion that is not coated with the active material and
coated portions formed on both sides while sandwiching the
non-coated portion therebetween and coated with the active
material. The current collector is folded at the non-coated portion
such that the coated portions on both sides face each other, and
further, a part of the non-coated portion is folded outward,
thereby forming the current collecting terminal. The first
electrode plate is sandwiched between the coated portions on both
sides to configure the layered structure.
[0034] With the above-described second electrode plate, the coated
portions on both sides are formed while sandwiching the linear
non-coated portion therebetween, and then, are folded at the
non-coated portion, and further, the current collecting terminal is
formed by folding a part of the non-coated portion outward.
Therefore, the common current collecting terminal collects a
current at the two coated portions, thus suppressing variations of
current collecting efficiency to enhance the current collecting
efficiency. Moreover, the current collecting terminal can be used
commonly to the two coated portions, thereby reducing the number of
current collecting terminals to be welded to simplify a welding
work. Moreover, a part of the non-coated portion is folded to form
the current collecting terminal, dispensing with forming the
current collecting terminal at the coated portion or welding and
connecting the current collecting terminal to the coated portion.
In addition, the non-coated portion is linear, and therefore, the
current collector can be coated with the active material in a strip
fashion in the manufacturing step for the second electrode plate,
thus enhancing production efficiency of the second electrode
plate.
Advantages of the Invention
[0035] According to the present invention such configured as
described above, it is possible to commonly use a current
collecting terminal at two active material retaining portions that
retain an active material to prevent variations of current
collecting efficiency, and further, reduce the number of current
collecting terminals, thus not only simplifying a welding work but
also facilitating work for layering a plurality of electrode
plates.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] FIG. 1 depicts a vertically cross-sectional view showing a
cylindrical battery in the present embodiment
[0037] FIG. 2 depicts a laterally cross-sectional view showing the
cylindrical battery in the present embodiment
[0038] FIG. 3 depicts a perspective view showing an electrode group
in the embodiment
[0039] FIG. 4 depicts a plan view, a front view, and a perspective
view showing a positive electrode plate in the embodiment
[0040] FIG. 5 depicts a plan view showing the positive electrode
plate in a developed state in the embodiment
[0041] FIG. 6 depicts views showing manufacturing processes for the
positive electrode plate in the embodiment
[0042] FIG. 7 depicts views showing a modification of the
manufacturing processes for the positive electrode plate in the
embodiment
[0043] FIG. 8 depicts a plan view, a front view, and a perspective
view showing a negative electrode plate in the embodiment
[0044] FIG. 9 depicts a plan view showing the negative electrode
plate in a developed state in the embodiment
[0045] FIG. 10 depicts views showing manufacturing processes for
the negative electrode plate in the embodiment
[0046] FIG. 11 depicts a vertically cross-sectional view showing
the electrode group in the embodiment
[0047] FIG. 12 depicts views showing a separator containing process
in the electrode group in the embodiment
[0048] FIG. 13 depicts views showing a negative electrode plate
folding process and a positive electrode plate folding process in
the electrode group in the embodiment
[0049] FIG. 14 depicts a developed perspective view showing the
cylindrical battery in the embodiment
[0050] FIG. 15 depicts a plan view, a front view, and a perspective
view showing a positive electrode plate in a modified
embodiment
[0051] FIG. 16 depicts views showing manufacturing processes for
the positive electrode plate in the modified embodiment
[0052] FIG. 17 depicts a plan view and a perspective view showing a
modification of the negative electrode plate
[0053] FIG. 18 depicts a vertically cross-sectional view showing a
cylindrical battery in a modified embodiment
[0054] FIG. 19 depicts a laterally cross-sectional view showing the
cylindrical battery in the modified embodiment;
[0055] FIG. 20 depicts a laterally cross-sectional view of a
cylindrical battery showing a modification of a spacer
[0056] FIG. 21 depicts a perspective view showing the spacer in the
modified embodiment
[0057] FIG. 22 depicts a front view showing, in partly enlargement,
the spacer in the modified embodiment
[0058] FIG. 23 depicts a view showing a state in which the spacer
and an electrode group are contained in a battery case in the
modified embodiment
[0059] FIGS. 24(A) to 24(C) depict schematic views showing a
modification of a layered pattern of a layered electrode group
[0060] FIG. 25 depicts a side view, a plan view, and a front view
showing a modification of a layered electrode group
MODE FOR CARRYING OUT THE INVENTION
[0061] A description will be given below of one embodiment of a
cylindrical battery according to the present invention with
reference to the attached drawings.
[0062] A cylindrical battery 100 in the present embodiment is an
alkaline secondary battery such as a nickel-cadmium storage battery
or a nickel-metal hydride storage battery. Specifically, the
cylindrical battery 100 may be of a low capacity type such as an AA
size battery capacity of 1800 mAh or less or an AAA size battery
capacity of 650 mAh or less. As shown in FIGS. 1 and 2, the
cylindrical battery 100 includes a metallic battery case 2 formed
into a bottomed cylindrical shape and an electrode group 3 formed
into a substantially rectangular parallelepiped shape that is
housed inside the battery case 2 and includes a positive electrode
plate 31, a negative electrode plate 32, and a separator 33.
[0063] The battery case 2 is formed into a shape of a bottomed
cylinder plated with nickel. As shown in FIG. 1, an upper opening
is sealed with a sealant 5 via an insulator 4. The back surface of
the sealant 5 is connected with a current collecting terminal 311
projecting from the upper end of the positive electrode plate 31
directly by welding or via a current collecting plate, not shown,
and thus, the sealant 5 serves as a positive electrode terminal.
Here in the present embodiment, a current collecting terminal 321
of the negative electrode plate 32 positioned at the outermost side
of the electrode group 3 is welded onto a bottom 2B of the battery
case 2, as described later.
[0064] The electrode group 3 is formed into the substantially
rectangular parallelepiped shape by layering the positive electrode
plate 31 and the negative electrode plate 32 via the separator 33
made of, for example, a polyolefin non-woven fabric (see FIG. 3).
Incidentally, the separator 33 is impregnated with an electrolyte
solution including potassium hydroxide or the like.
[0065] The positive electrode plate 31 includes a positive
electrode current collector that is made of foamed nickel and is
filled with a mixture of a nickel hydroxide active material and a
conductive cobalt compound (hereinafter simply referred to as a
positive active material) at the hollow thereof. Here, the nickel
hydroxide active material is nickel hydroxide, for example, in the
case of the nickel-cadmium storage battery or nickel hydroxide
added with calcium hydroxide in the case of the nickel-metal
hydride storage battery.
[0066] Specifically, the positive electrode plate 31 includes an
active material non-retaining portion 31A that is linearly formed
and does not retain a positive active material and active material
retaining portions 31B that are formed on both sides of the active
material non-retaining portion 31A sandwiched therebetween and
retain a positive active material, as shown in FIGS. 4 and 5. The
active material non-retaining portion 31A is symmetrically formed
in such a manner as to include the center line H1 of the positive
electrode current collector, and the active material retaining
portions 31B are symmetrically formed with respect to the active
material non-retaining portion 31A (see FIG. 5).
[0067] As shown in FIG. 4, in the positive electrode plate 31, the
positive electrode current collector is folded in a substantial
U-shape at the active material non-retaining portion 31A in such a
manner that the active material retaining portions 31B on both
sides face each other. Specifically, while the boundary between the
active material non-retaining portion 31A and each of the active
material retaining portions 31B or a slightly inward of the
boundary is used as a folded line, the positive electrode plate 31
is folded such that the active material non-retaining portion 31A
and each of the active material retaining portions 31B form right
angles with respect to each other.
[0068] Moreover, in the positive electrode plate 31, the current
collecting terminal 311 made of, for example, a nickel steel plate
is placed on the active material non-retaining portion 31A serving
as the folded portion formed between the two active material
retaining portions 31B. The current collecting terminal 311 extends
outward in one width direction perpendicular to a facing direction
in which the two active material retaining portions 31B face each
other. In FIG. 4, the current collecting terminal 311 extends
outward in one direction (i.e., forward in FIG. 4) in the same
direction as a straight direction of the active material
non-retaining portion 31A. The current collecting terminal 311 is
disposed over substantially the entire active material
non-retaining portion 31A in order to enhance current collection
efficiency of the positive electrode current collector. Besides the
positive electrode current collector that extends in the same
direction as the active material non-retaining portion 31A, the
positive electrode current collector may be inclined as long as it
extends from the side of the active material non-retaining portion
31A (an upper side edge 31m or a lower side edge 31n in the plan
view of FIG. 4 or FIG. 5). In this manner, the current collecting
terminal 311 extends outward in one width direction perpendicular
to the facing direction in which the two active material retaining
portions 31B face each other. Therefore, when the positive
electrode plate 31 in the expanded state is contained in such a
manner as to be sandwiched between the two folded portions of the
separator 33, the folded portion of the separator 33 is located at
the side 31n facing the side 31m at which the current collecting
terminal 311 extends outward, so that the current collecting
terminal 311 cannot interfere the containing work in the separator
33.
[0069] Next, brief explanation will be made on a manufacturing
method for the positive electrode plate 31 such configured as
described above.
[0070] First, as illustrated in FIG. 6, a portion serving as an
active material non-retaining portion (i.e., a non-retaining region
X1), which is linearly formed, is pressed against an elongated
preform (i.e., a current collector substrate) X made of foamed
nickel at the center along a longitudinal direction (a pressing
step). Subsequently, the preform X is filled with a positive active
material such that portions other than the non-retaining region X1
become active material retaining portions (i.e., retaining regions
X2) (an active material filling step). After the active material
filling step, the entire current collector substrate is pressed (an
electrode plate pressing step). Thereafter, the preform X is cut in
a direction perpendicular to the non-retaining region X1 in such a
manner as to form the same shape as that of the positive electrode
plate (except the terminal) in the developed state (a cutting
step). Here, broken lines in FIG. 6 indicate cutting lines. The
current collecting terminal 311 is welded to the active material
non-retaining portion 31A of the positive electrode current
collector obtained by cutting in the above-described manner (a
terminal welding step). In this manner, the positive electrode
plate 31 in the developed state is formed. With this method, it is
possible to reduce a loss of the positive active material, thus
reducing a manufacturing cost.
[0071] In the above-described method, the active material
non-retaining portion 31A can be formed without filling the preform
X with the positive active material, and then, the active material
retaining portions 31B are formed on both sides of the active
material non-retaining portion 31A while sandwiching the active
material non-retaining portion 31A therebetween. Consequently, each
of the active material retaining portions 31B and the active
material non-retaining portion 31A are different in a percentage of
elongation from each other, and thus, they may be possibly broken
at the boundary portion therebetween. In view of this, using a
method below may be conceived. That is to say, as illustrated in
FIG. 7, the entire preform X (i.e., the entire current collector
substrate) made of foamed nickel is filled with a positive active
material (an active material filling step). After this active
material filling step, the entire current collector substrate X is
pressed (an electrode plate pressing step). Subsequently, the
positive active material is removed by ultrasonic removal or the
like such that a non-retaining region X1 serving as an active
material non-retaining portion 31A, which is linearly formed, is
formed at the center of the preform X filled with the positive
active material (an active material removing step). The
non-retaining region X1 in the preform X having the non-retaining
region X1 formed therein is pressed (a pressing step). Thereafter,
the preform X having the non-retaining region X1 pressed thereat is
cut in a direction perpendicular to the non-retaining region X1 (a
cutting step). Here, broken lines in FIG. 7 indicate cutting lines.
The current collecting terminal 311 is welded to the active
material non-retaining portion 31A of the positive electrode
current collector obtained by cutting in the above-described manner
(a terminal welding step). In this manner, the positive electrode
plate 31 in the developed state is formed.
[0072] Alternatively, the cutting step may be performed between the
plate pressing step and the active material removing step. In other
words, the entire preform X (i.e., the entire current collector
substrate) made of the foamed nickel is filled with the positive
active material (an active material filling step). After this
active material filling step, the entire current collector
substrate X is pressed (an electrode plate pressing step).
Subsequently, the pressed preform X is cut into the developed shape
of the positive electrode plate 31 (a cutting step). And then, the
positive active material is removed by ultrasonic removal or the
like such that a non-retaining region X1 serving as an active
material non-retaining portion 31A, which is linearly formed, is
formed at the center of the cut preform X filled with the positive
active material (an active material removing step). The
non-retaining region X1 in the preform X having the non-retaining
region X1 formed therein is pressed (a pressing step). In the end,
the current collecting terminal 311 is welded to the active
material non-retaining portion 31A of the positive electrode
current collector (a terminal welding step).
[0073] The negative electrode plate 32 includes a negative
electrode current collector made of a plate-like porous steel plate
plated with nickel, for example, and a negative active material
coating the negative electrode current collector. Here, the
negative active material is a mixture of cadmium oxide powder and
metallic cadmium powder, for example, in the case of the
nickel-cadmium storage battery, or powder of a hydrogen storage
alloy of an AB.sub.5 type (rare earth based) or an AB.sub.2 type (a
Laves phase), for example, in the case of the nickel-metal hydride
storage battery.
[0074] Specifically, the negative electrode plate 32 includes an
active material non-retaining portion (non-coating part) 32A that
is linearly formed and does not retain a negative active material
and active material retaining portions (coating part) 32B that are
formed on both sides of the active material non-retaining portion
32A sandwiched therebetween and retain a negative active material,
as shown in FIGS. 8 and 9. The active material non-retaining
portion 32A is symmetrically formed in such a manner as to include
the center line H2 of the negative electrode current collector, and
the negative active material retaining portions 32B are
symmetrically formed with respect to the active material
non-retaining portion 32A (see FIG. 9).
[0075] As shown in FIG. 8, in the negative electrode plate 32, the
negative electrode current collector is folded in a substantial
U-shape at the active material non-retaining portion 32A in such a
manner that the negative active material retaining portions 32B on
both sides face each other. Specifically, the boundary between the
active material non-retaining portion 32A and each of the negative
active material retaining portions 32B or a slightly inward of the
boundary is used as a folded line, and then, the negative electrode
plate 32 is folded such that the active material non-retaining
portion 32A and each of the negative active material retaining
portions 32B form right angles with respect to each other.
[0076] Moreover, a part of the active material non-retaining
portion 32A is folded outward, thereby forming the current
collecting terminal 321 that is welded and connected onto the
bottom 2B of the battery case 2 in the negative electrode plate 32.
Specifically, a cutout 32C in the conformity with the desired shape
of the current collecting terminal is formed at a part of the
active material non-retaining portion 32A, and then, the inside of
the cutout 32C is folded outward, thus obtaining the current
collecting terminal 321.
[0077] In the cutout 32C, both of a cutout starting point a and a
cutout ending point b are located on the boundary between the
active material non-retaining portion 32A and the negative active
material retaining portion 32B, as illustrated in FIG. 9. A cutout
line c connecting the cutout starting point a and the cutout ending
point b to each other is contained inside the active material
non-retaining portion 32A. In the present embodiment, the desired
shape of the current collecting terminal is rectangular, and
therefore, the cutout line c is formed into a substantial U-shape,
as viewed on the plane.
[0078] While the boundary between the active material non-retaining
portion 32A and the negative active material retaining portion 32B
or slightly inward of the boundary is used as a folding line, the
current collecting terminal 321 formed inside the cutout 32C is
folded outward of the negative active material retaining portion
32B in a facing direction in which the negative active material
retaining portions 32B face each other. In the folded state, the
planar direction of the active material non-retaining portion 32A
and the planar direction of the current collecting terminal 321 are
substantially the same as each other, and further, the active
material non-retaining portion 32A and the current collecting
terminal 321 are located within substantially the same plane.
Consequently, in the state in which the negative electrode plate 32
is contained inside the battery case 2, the active material
non-retaining portion 32A can be brought into contact with the
bottom 2B of the battery case 2, and further, the current
collecting terminal 321 can be brought into contact with the bottom
2B of the battery case 2. As a consequence, when the current
collecting terminal 321 is welded, the negative electrode plate 32
can be stabilized inside the battery case 2, thereby facilitating a
welding work. In addition, the flat active material non-retaining
portion 32A can be disposed in such a manner as to be brought into
contact with the bottom 2B of the battery case 2, thus effectively
utilizing a space defined inside the battery case 2.
[0079] Next, brief explanation will be made on a manufacturing
method for the negative electrode plate 32 such configured as
described above.
[0080] First, as illustrated in FIG. 10, an elongated preform
(i.e., a current collector substrate) Y made of a porous steel
plate is coated on both sides of a linear non-coated region Y1 with
a negative active material with the non-coated region Y1 remaining
at the center along a longitudinal direction, thus forming coating
regions Y2 and Y3 (a coating step). And then, the substantially
U-shaped cutout 32C is punched in the non-coated region Y1 by using
a punch die (a punching step). Thereafter, the preform Y is cut in
conformity with the same shape as that of the developed state of
the negative electrode plate 32 (a cutting step). Here, broken
lines in FIG. 10 indicate cutting lines. In this manner, the
negative electrode plate 32 in the developed state can be formed.
Incidentally, the cutout 32C may be formed after the negative
electrode plate 32 is cut.
[0081] Hence, the layered electrode group 3 in the present
embodiment is configured by layering the positive electrode plate
31 having the two active material retaining portions 31B disposed
opposite to each other in the substantial U-shape and the negative
electrode plate 32 having the two active material retaining
portions 32B disposed opposite to each other in the substantial
U-shape in such a manner as to be interlaced with each other.
Specifically, the electrode plates are layered such that one of the
active material retaining portions 31B in the positive electrode
plate 31 is sandwiched between the two active material retaining
portions 32B in the negative electrode plate 32 whereas one of the
active material retaining portions 32B in the negative electrode
plate 32 is sandwiched between the two active material retaining
portions 31B in the positive electrode plate 31, as shown in FIG.
11. In the present embodiment, the electrode plates are layered
such that the folded portion (the active material non-retaining
portion 31A) of the positive electrode plate 31 and the folded
portion (the active material non-retaining portion 32A) of the
negative electrode plate 32 are opposite to each other. Here,
although clearances are defined between each of the electrode
plates 31 and 32 and the separator 33 in FIGS. 1, 2, 11, and the
like, for the sake of easy understanding, they are actually brought
into contact with each other in stacking.
[0082] More particularly, the layered electrode group 3 in the
present embodiment is constituted of the two negative electrode
plates 32 and one positive electrode plate 31. The electrode plates
are layered such that one active material retaining portion 32B of
each of the adjacent two negative electrode plates 32 (the active
material retaining portions 32B adjacent to each other in the two
negative electrode plates 32) is sandwiched between the two active
material retaining portions 31B of the one positive electrode plate
31.
[0083] Next, explanation will be made on a manufacturing method for
the layered electrode group 3 such configured as described
above.
[0084] First, as shown in FIGS. 12 and 13, the positive electrode
plate 31 in the developed state, the negative electrode plate 32 in
the developed state, and the separator 33 in the developed state
are prepared. As shown in FIG. 12, the positive electrode plate 31
in the developed state is placed at one half surface with respect
to a folding line 33a of the separator 33. At this time, the
positive electrode plate 31 is placed such that a side edge (i.e.,
the lower side edge 31n), opposite to a side edge (i.e., the upper
side edge 31m) on which the current collecting terminal 311 extends
outside, is aligned with the folding line 33a of the separator 33.
Then, the separator 33 is folded into two along the folding line
33a (a separator containing step). In this manner, the folded
portion of the separator 33 is located on the lower side edge 31n
of the positive electrode plate 31, so that the positive electrode
plate 31 in the developed state is contained in the separator 33
except the portion of the current collecting terminal 311 extending
outward. And then, four corners of the separator 33 containing the
positive electrode plate 31 therein or three sides of the upper,
right, and left sides except the positive electrode terminal
portion are securely welded by ultrasonic welding or the like.
Here, there are cutouts 33b at the current collecting terminal
portion of the positive electrode plate 31 in the separator 33.
Consequently, when the current collecting terminal 311 is folded,
the separator 33 can be prevented from curling up according to the
deformation of the current collecting terminal 311. Incidentally,
the use of an envelope-like separator 33 having three sides thereof
closed in advance enables the positive electrode plate 32 to be
packed.
[0085] Next, as shown in FIG. 13, the active material retaining
portions 31B disposed on the right and left of the positive
electrode plate 31 in the developed state, contained in the
separator 33 are layered on one of the active material retaining
portions 32B of the negative electrode plate 32 in the developed
state. And then, the negative electrode plate 32 in the developed
state is folded into a substantial U-shape, so that each of the two
active material retaining portions 31B of the positive electrode
plate 31 is sandwiched by the negative electrode plate 32 (a
negative electrode plate folding step). At this time, the current
collecting terminal 321 is folded outward from the active material
non-retaining portion 32A of the negative electrode plate 32.
Thereafter, the positive electrode plate 31 sandwiched on the right
and left thereof by the negative electrode plate 32 is folded into
a substantial U-shape (a positive electrode plate folding step). In
this manner, the layered electrode group 3 is formed. A bundle tape
34 is wound around the layered electrode group 3 such formed as
described above, thus preventing the layered electrode group 3 from
being untied.
[0086] Moreover, the cylindrical battery 100 in the present
embodiment includes a spacer 6 for fixing the electrode group 3 to
the battery case 2, as shown in FIGS. 1 and 2. The spacer 6 is
interposed between the inside circumferential surface of the
battery case 2 and the side surface of the electrode group 3, and
includes a pair of spacers 61 and 62 for fixing the electrode group
3 to the battery case 2. The pair of spacers 61 and 62 is disposed
in a space defined between the inside circumferential surface of
the battery case 2 and the side surface of the electrode group 3,
and then, sandwiches the electrode group 3 in a layered direction
L. Here, the layered direction L accords with the facing direction
in which the respective active material retaining portions 31B and
32B of the electrode plates 31 and 32 face each other.
[0087] The pair of spacers 61 and 62 is made of a resin such as an
acrylic resin or a polypropylene resin or a metal such as stainless
steel, and further, is formed into the same shape as each
other.
[0088] Each of the spacers 61 and 62 has the same cross-sectional
shape in a center axis direction C, and further, is brought into
contact with substantially the entire outside surfaces 3a and 3b of
the layered electrode group 3 (see FIG. 2). Moreover, each of the
spacers 61 and 62 is vertically brought into contact with the
inside circumferential surface of the battery case 2. Consequently,
the entire electrode group 3 is uniformly pressed by the pair of
spacers 61 and 62, thus enhancing electric charge-discharge
efficiency.
[0089] It is conceived that a portion of each of the spacers 61 and
62 in contact with the battery case 2 is formed into an arcuate
shape so as to be brought into contact within a predetermined range
of the battery case 2 in a circumferential direction in order to
disperse a pressing force exerted on the battery case 2. Here, in
the case where the mechanical strength of the battery case 2 can be
satisfactorily secured, a portion in contact with the battery case
2 may be formed into a square shape. When the portion in contact
with the battery case 2 is formed into a square shape, a space
defined between each of the spacers 61 and 62 and the battery case
2 can be made large, thus contributing to an increase in
electrolyte solution amount and a reduction of an increase in inner
pressure.
[0090] Subsequently, a manufacturing method for the cylindrical
battery 100 such configured as described above will be simply
described with reference to FIG. 14. Here, the bundle tape 34 is
not shown in the electrode group 3 shown in FIG. 14.
[0091] The above-described layered electrode group 3 is housed
inside the battery case 2, and then, the current collecting
terminal 321 of the negative electrode plate 32 is connected by
welding onto the bottom 2B of the battery case 2. Thereafter, the
electrode group 3 is sandwiched between the pair of spacers 61 and
62 in the layered direction L, and then, the electrolyte solution
is filled into the battery case 2. Subsequently, the current
collecting terminal 311 of the positive electrode plate 31 is
connected to the back surface of the sealant 5 directly or via the
current collecting plate, not shown, and further, the sealant 5 is
securely caulked to the upper opening formed at the battery case 2
via the insulator 4.
Effects of the Present Embodiment
[0092] With the cylindrical battery 100 in the present embodiment
such configured as described above, the positive electrode plate 31
and the negative electrode plate 32 are formed into the substantial
U-shape such that the two active material retaining portions 31B
and 32B are disposed opposite to each other. The common current
collecting terminals 311 and 321 can collect currents at the two
active material retaining portions 31B and 32B, thus suppressing
variations in current collection efficiency so as to enhance the
current collection efficiency. Moreover, the current collecting
terminals 311 and 321 can be commonly used by the two active
material retaining portions 31B and 32B, and therefore, the number
of current collecting terminals 311 and 321 to be welded can be
reduced, thereby simplifying the welding work. Additionally, the
positive electrode plate 31 and the negative electrode plate 32
formed into the substantial U-shape are layered in an interlaced
manner, and therefore, the plurality of positive electrode plates
31 and negative electrode plates 32 can be simply layered. In
addition, after the stacking, the layered electrode group 3 is
hardly untied.
[0093] Furthermore, the electrode group 3 having the positive
electrode plate 31 and the negative electrode plate 32 layered via
the separator 33 is housed inside the battery case 2, thereby
providing the cylindrical battery without winding misalignment
occurring at the electrode group 3 or various problems incidental
to such winding misalignment. Moreover, since the battery case 2 is
formed into the cylindrical shape, it can become resistant against
an increase in inside pressure. Additionally, the spacers 61 and 62
securely press the electrode group 3 inside the battery case 2,
thus preventing any play of the electrode group 3 with respect to
the battery case 2. Consequently, it is possible to suppress the
active material in the electrode plates 31 and 32 from falling so
as to not only prevent degradation of electric charge-discharge
performance but also enhance the electric charge-discharge
performance.
[0094] The present invention is not limited to the above-described
embodiment. For example, in the embodiment, in the positive
electrode plate 31, the active material non-retaining portion 31A
and the active material retaining portion 31B are constituted of
one positive electrode current collector, but it is not limited to
this. Specifically, the positive electrode plate 31 may be provided
with two active material retaining plates 31s and 31t that retain a
positive active material in a positive electrode current collector
and a current collecting terminal 31u for connecting the two active
material retaining plates 31s and 31t to each other, as shown in
FIG. 15. The active material retaining plates 31s and 31t are
formed into the same shape as each other, and specifically, are
constituted by filling a substantially rectangular foamed nickel
with a positive active material. An active material removal part
31x used for welding the current collecting terminal 31u is formed
at a part of each of the active material retaining plates 31s and
31t. The current collecting terminal 31u is formed into a
substantial T-shape, as viewed on a plane. The right and left ends
of a horizontal part 31u1 of the T-shape are welded to the active
material removal parts 31x of the active material retaining plates
31s and 31t. In this developed state, a vertical part 31u2 of the
T-shape of the current collecting terminal 31u constitutes an
extension portion extending outward of the active material
retaining plates 31s and 31t in a width direction. The positive
electrode plate 31 is folded in a substantial U-shape at the
horizontal part 31u1 of the T-shape the current collecting terminal
31u in such a manner that the two active material retaining plates
31s and 31t face each other, and further, the vertical part 31u2 of
the P-shape extends outward on one side in the width direction
perpendicular to the direction in which the two active material
retaining plates 31s and 31t face each other.
[0095] Next, brief explanation will be made on a manufacturing
method for the positive electrode plate 31 such configured as
described above. As illustrated in FIG. 16, the entire elongated
preform Z made of foamed nickel (i.e., a current collector
substrate) is filled with an active material (an active material
filling step). After the active material filling step, the entire
current collector substrate is pressed (an electrode plate pressing
step). Subsequently, the preform Z filled with the active material
is cut into the size of each of the active material retaining
portions 31s and 31t (a cutting step). And then, the positive
active material is removed by ultrasonic removing or the like so as
to form the active material removal part 31x formed into the
substantially rectangular shape at the center on the short side of
each of the cut active material retaining portions 31s and 31t (an
active material removing step). Thereafter, the respective ends of
the horizontal part 31u1 of the T-shape of the T-shaped terminal
31u are welded to the two active material removal parts 31x (a
terminal welding step). Here, the T-shaped terminal is not limited
to an integral terminal, and two current collecting terminals
formed into a strip-like shape may be welded to each other in a
T-shape. Alternatively, the two active material retaining portions
31s and 31t may be connected to each other via a connecting member
other than the current collecting terminal, and then, the current
collecting terminal may be welded to the connecting member.
[0096] Although the current collecting terminal 321 of the negative
electrode plate 32 in the above-described embodiment has been
folded outward of the active material retaining portion 32B while
using the boundary between the active material non-retaining
portion 32A and the active material retaining portion 32B as the
folding line, the folding line may not be the boundary between the
active material non-retaining portion 32A and the active material
retaining portion 32B. Additionally, as illustrated in FIG. 17, the
current collecting terminal 321 may extend outward on one side in
the width direction perpendicular to the direction in which the
active material retaining portions 32B face each other. In this
case, it is possible to increase the degree of freedom of choices
of the length of the current collecting terminal 321. Here, the
positive electrode plate 31 may adopt the configuration of the
negative electrode plate 32. Alternatively, the negative electrode
plate 32 may adopt the same configuration as that of the positive
electrode plate 31 in the above-described embodiment. Furthermore,
even if the current collecting terminal 321 is not welded to the
battery case 2, only a contact can achieve conduction.
[0097] Moreover, although the positive electrode plate and the
negative electrode plate have been formed into the substantial
U-shape obtained by folding them in the substantial U-shape in one
embodiment, they may be folded into a substantial V-shape or
literally the substantial U-shape.
[0098] Each of the spacers is not limited to that in the
above-described embodiment. Vertically (the center axis direction
C) communicating spaces S, into which welding rods for welding the
current collecting terminal 321 of the negative electrode plate 32
at the electrode group 3 onto the bottom 2B of the battery case 2,
may be formed, as shown in FIGS. 18 and 19. The space S
communicates from the bottom 2B of the battery case 2 toward the
upper opening of the battery case 2. Specifically, each of the
spacers 61 and 62 has a vertically communicating insertion hole 6H,
into which a welding rod is inserted. The insertion hole 6H may be
formed into any shapes as long as the insertion of the welding rod
achieves welding, and therefore, it is not limited to a circle but
a polygon or an ellipse. The insertion hole 6H is formed at such a
position that the current collecting terminal 321 of the negative
electrode plate 32 can be contained inside the insertion hole 6H in
the state in which the electrode group 3 is fixed by the spacers 61
and 62, and further, is determined according to the position of the
current collecting terminal 321 of the negative electrode plate
32.
[0099] In this manner, since each of the spacers 61 and 62 has the
insertion holes 6H formed thereat, the current collecting terminal
321 of the negative electrode plate 32 can be welded after the
electrode group 3 and the spacers 61 and 62 are inserted into the
battery case 2. In the case where the spacers 61 and 62 are
inserted after the current collecting terminal 321 of the negative
electrode plate 32 is welded, the position of the electrode group 3
may be possibly changed before and after the spacers 61 and 62 are
inserted, thereby raising a fear of the rupture or breakage
occurring at the welded portion. However, the welding after
insertion of the spacers 61 and 62 does not raise the problem.
[0100] Besides securing the welding spaces with the insertion holes
6H formed at the spacers 61 and 62, welding spaces may be defined
according to the shape of the outside appearance of the spacers 61
and 62 without forming the insertion holes 6H formed at the spacers
61 and 62, as shown in FIG. 20. Specifically it is conceived that
the shape of the outside appearance of the spacers 61 and 62 has
recesses 6M formed at side surfaces thereof and has the same
cross-sectional shape in a center axis direction C. In FIG. 20,
there are provided an electrode contact portion 6A in contact with
the outermost surface of the electrode group 3 in the layered
direction, a case contact portion 6B in contact with the inner
circumferential surface of the battery case 2, and the recesses 6M
formed therebetween. With this configuration, after the spacers 61
and 62 are inserted, the current collecting terminal 321 of the
negative electrode plate 32 can be welded to the bottom 2B of the
battery case 2 with the welding spaces defined by the recesses 6M
formed at the spacers 61 and 62.
[0101] Specifically, the spacer 6 is formed into an equal
cross-sectional shape having the rectangular plate-like electrode
contact portion 6A having a contact surface on one surface 6a in
contact with the substantially the entire outermost surface
(specifically, the negative electrode plate 32) of the electrode
group 3 in the layered direction L and the two case contacts GB
extending from the other surface 6b of the electrode contact
portion 6A and being brought into contact with the inside
circumferential surface 2A of the battery case 2, as shown in FIGS.
21 and 22.
[0102] The electrode contact portion 6A has substantially the same
shape as the outermost surface of the electrode group 3 in the
layered direction L. At the upper portion of the electrode contact
portion 6A is formed a projecting piece 6T facing the upper surface
of the electrode group 3. The projecting piece 6T substantially
extends perpendicularly from one surface 6a of the electrode
contact portion 6A at the upper end center of the electrode contact
portion 6A. Moreover, a wall 6P surrounding the upper corner of the
electrode group 3 is formed at an upper corner of the electrode
contact portion 6A. The surrounding wall GP includes an upper wall
6P1 facing the upper surface of the electrode group 3 and side
walls 6P2 facing right and left side surfaces of the electrode
group 3 (see FIG. 22).
[0103] The two case contacts 6B are formed in parallel along the
center axis direction C at the other surface 6b of the electrode
contact portion BA. Specifically, the two case contacts 6B are
symmetrically formed in such a manner as to sandwich the center
axis of the battery case 2 in the state contained in the battery
case 2. A contact portion with the inside circumferential surface
2A of the battery case 2 at the case contact portion 6B has
substantially the same curve as that of the inside circumferential
surface 2A of the battery case 2. As a consequence, the spacer 6 is
such configured that the case contact portion 6B and the battery
case 2 are brought into surface contact with each other (see FIG.
23).
[0104] When the electrode group 3 is disposed in the battery case 2
in such a manner as to be sandwiched in the above-described spacer
6, the projecting pieces 6T of the two spacers 6, as shown in FIG.
23, contact and press the current collecting terminal 311 of the
positive electrode plate 31. Incidentally, a free end side beyond a
portion in contact with the projecting piece 6T in the current
collecting terminal 311 is folded, to be thus welded to the sealant
5. Here, the current collecting terminal 311 rises at a position
near the projecting piece 6T. Moreover, the surrounding walls 6P of
the two spacers 6 contain therein the upper corners of the positive
electrode plate 31 and the negative electrode plate 32.
[0105] The formation of the projecting piece 6T facing the upper
surface of the electrode group 3 brings the projecting piece 6T
into contact with the current collecting terminal 311 welded to the
upper surface of the positive electrode plate 31, thus preventing
the current collecting terminal 311 from being positionally
misaligned, and further, preventing the welded portion of the
current collecting terminal 311 from being broken and peeled off.
Moreover, the formation of the surrounding wall 6P surrounding the
upper corner of the electrode group 3 at the upper portion of the
spacer 6 can prevent the battery case 2 and the positive electrode
plate 31 from being brought into contact with each other, and
further, can prevent the current collecting terminal 311 of the
positive electrode plate 31 and the negative electrode plate 32
from being brought into contact with each other. Additionally, it
is possible to prevent any misalignment of the positive electrode
plate 31 and the negative electrode plate 32 in the electrode group
3. In addition, the formation of the surrounding wall 6P can
eliminate disposing an upper insulating plate that has been
required in the related art, thus simplifying the manufacturing
process, and further, reducing a material cost.
[0106] Although the layered electrode group 3 in the embodiment has
been constituted of one positive electrode plate 31 and the two
negative electrode plates 32 in stacking, a plurality of positive
electrode plates 31 and a plurality of negative electrode plates 32
may be layered one on another.
[0107] In this case, as shown in FIG. 24A, the electrode group 3 is
conceived to be layered such that the positive electrode plate 31
sandwiches one active material retaining portion 32B in each of the
two adjacent negative electrode plates 32 therebetween whereas the
negative electrode plate 32 sandwiches one active material
retaining portion 31B in each of the two adjacent positive
electrode plates 31 therebetween except electrode plates located on
both outer sides in a layered direction (i.e., the negative
electrode plates 32 in FIG. 24A). In this manner, the positive
electrode plates 31 and the negative electrode plates 32 are
layered to be sandwiched therebetween, so that the layered
electrode group can be hardly misaligned.
[0108] Alternatively, as shown in FIG. 24B, a plurality of units,
each consisting of one positive electrode plate 31 and the two
negative electrode plates 32 in stacking in the above-described
embodiment, may be layered. In this case, an increase or decrease
in number of units can match with the size of the battery case, and
further, can readily increase or decrease the capacity of the
battery.
[0109] In addition, as shown in FIG. 24C, two active material
retaining portions 31B of one positive electrode plate 31 are
sandwiched between two active material retaining portions 32B of
one negative electrode plate 32 in stacking. In this manner, one
positive electrode plate 31 and one negative electrode plate 32 can
manufacture a unit of a minimum capacity. An increase or decrease
in number of units can finely increase or decrease the capacity of
the battery.
[0110] Moreover, the layered electrode group is not limited to the
layered configuration in which the active material non-retaining
portion 31A of the positive electrode plate 31 and the active
material non-retaining portion 32A of the negative electrode plate
32 face each other, like the above-described embodiment. As shown
in FIG. 25, the electrode group may be configured in stacking such
that the active material non-retaining portion 31A of the positive
electrode plate 31 and the active material non-retaining portion
32A of the negative electrode plate 32 do not face each other. In
other words, the active material non-retaining portion 31A of the
positive electrode plate 31 and the active material non-retaining
portion 32A of the negative electrode plate 32 may be arranged at
right angles in stacking.
[0111] The present invention may be applicable to a secondary cell
such as a lithium-ion secondary cell or to a primary cell, besides
the alkaline secondary battery. Moreover, the present invention may
be applicable to a prismatic cell, besides the cylindrical
battery.
[0112] Furthermore, it is to be understood that the present
invention should not be limited to the above-described embodiment,
and therefore, can be variously modified without departing from the
scope.
INDUSTRIAL APPLICABILITY
[0113] According to the present invention, the current collecting
terminal is commonly used by the two active material retaining
portions that retain the active material therein, thus preventing
any variations of the current collecting efficiency, and further,
the decrease in number of current collecting terminals can not only
simplify the welding work but also simplify the operation for
layering the plurality of electrode plates.
* * * * *