U.S. patent application number 09/391364 was filed with the patent office on 2002-05-23 for cell.
Invention is credited to INOUE, TAKEFUMI, YOSHIDA, HIROAKI.
Application Number | 20020061438 09/391364 |
Document ID | / |
Family ID | 27334222 |
Filed Date | 2002-05-23 |
United States Patent
Application |
20020061438 |
Kind Code |
A1 |
INOUE, TAKEFUMI ; et
al. |
May 23, 2002 |
CELL
Abstract
A cell is provided in which a flat plate portion of a collector
portion is prevented from making contact with a positive or
negative electrode in a power generating element to cause a short
circuit, the application area of a material can be widened, and
edge portions of an electrode plate can be surely connected and
fixed to a collector. In a collector portion of a negative or
positive collector, press holds of a gap (groove) which opens on
the side of a basal portion are formed by bending back a
substantially vertical metal plate at an apex. The portion between
adjacent press holds of the collector portion is formed into a flat
plate-like shape. A window is formed in each of the press holds, or
a reduced thick portion is formed in a part of each of the press
holds.
Inventors: |
INOUE, TAKEFUMI; (KYOTO-SHI,
JP) ; YOSHIDA, HIROAKI; (KYOTO-SHI, JP) |
Correspondence
Address: |
JACOBSON HOLMAN PLLC
400 SEVENTH STREET N.W.
SUITE 600
WASHINGTON
DC
20004
US
|
Family ID: |
27334222 |
Appl. No.: |
09/391364 |
Filed: |
September 8, 1999 |
Current U.S.
Class: |
429/161 ;
429/211; 429/94 |
Current CPC
Class: |
Y10T 29/49108 20150115;
Y02P 70/50 20151101; Y02E 60/10 20130101; H01M 50/538 20210101;
H01M 10/0431 20130101 |
Class at
Publication: |
429/161 ;
429/211; 429/94 |
International
Class: |
H01M 002/26 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 8, 1998 |
JP |
10-253390 |
Sep 8, 1998 |
JP |
10-253391 |
Nov 24, 1998 |
JP |
10-350692 |
Claims
What is claimed is:
1. A cell wherein a collector portion of each of collectors
comprises: plural press holds in each of which two metal plate
portions are projected to be opposed via a gap that opens on a side
of a basal portion, by bending back a substantially vertical metal
plate at an apex; and flat plate portions which are formed by a
flat metal plate portion and through which adjacent ones of aid
press holds are coupled to each other on the side of the basal
portion, said collector portions are respectively placed on ends of
a winding axis of a wound type power generating element, with
respectively directing the basal portions to the ends, said power
generating element being configured by winding strip positive and
negative electrodes with a strip separator therebetween with being
mutually shifted in the winding axis direction, and edge portions
of said positive and negative electrodes which protrude in the ends
of the winding axis of said power generating element are pressingly
held in nearest press holds of said collector portions to be
connected and fixed.
2. A cell according to claim 1, wherein said edge portions of said
electrodes are inserted between said two metal plate portions of
said corresponding press hold of said collector portions, and then
connected and fixed to said two metal plate portions by crimping
and ultrasonic welding.
3. A cell according to claim 1 or 2, wherein a window is formed in
a part of one of said metal plate portions of each of said press
holds of said collector portions of said collectors, said window
communicating with said gap between said one metal plate portion
and said other metal plate portion.
4. A cell according to claim 3, wherein said edge portions of said
electrodes are connected and fixed by inserting said edge portions
between said two metal plate portions of said corresponding press
hold of said collector portions and then crimping said metal plate
portions, and also by ultrasonic welding of said window of said one
metal plate portion and said other metal plate portion, and a part
of said one metal plate portion other than said window and said
other metal plate portion.
5. A cell comprising: a power generating element in which positive
and negative electrode plates are wound or laminated with a
separator therebetween and an edge portion of one of said electrode
plates protrudes from an edge portion of another one of said
electrode plates; and collectors respectively connected to said
edge portions, wherein each of said collectors is formed by bending
a metal plate to have plural groove portions which are used for
pressingly holding and bonding said edge portion of either of said
electrode plates, and a reduced thickness portion is formed in a
part of each of said groove portions.
6. A cell according to claim 5, wherein each of said collectors is
formed by a plate member of a thickness of 0.5 to 2 mm and said
reduced thickness portion has a thickness which is 10% to 80% of
the thickness of said collector.
Description
BACKGROUND OF THE INVENTION
[0001] The invention relates to a cell having a wound type power
generating element in which strip positive and negative electrodes
are wound with a strip separator therebetween.
[0002] FIG. 9 shows a configuration example of a non-aqueous
electrolyte secondary cell having a wound type power generating
element 1 of an elliptic cylindrical shape. The power generating
element 1 is configured by winding strip negative and positive
electrodes 1a and 1b with a strip separator 1c therebetween into an
elliptic cylindrical shape. The negative and positive electrodes 1a
and 1b are wound with being slightly shifted in the vertical
direction from each other, so that only upper edge portions of the
negative electrode 1a protrude from the upper end of the power
generating element 1 and only lower edge portions of the positive
electrode 1b protrude from the lower end. In this case, the active
material is not applied to the upper edge portions of the negative
electrode 1a, and to the lower edge portions of the positive
electrode 1b, thereby allowing metal foils of the negative and
positive electrodes 1a and 1b to be respectively exposed in the
upper and lower ends of the power generating element 1. The wound
separator 1c has a width at which the portion where the negative
and positive electrodes 1a and 1b overlap with each other is surely
covered and the upper and lower edge portions are not covered.
[0003] In such a non-aqueous electrolyte secondary cell,
conventionally, a negative collector 2 such as shown in FIG. 10 is
disposed on the upper end portion of the power generating element 1
so as to perform current collection on the negative electrode 1a.
The negative collector 2 consists of a copper plate and is
configured so that a collector portion 2a is formed above one side
with respect to the center of the upper end portion of the power
generating element 1. A flat plate-like terminal connector 2b is
drawn out from the collector portion 2a and placed above one
semicircular area of the upper end portion of the power generating
element 1. In the collector portion 2a, the copper plate is
repeatedly bent into a bellow-like shape so as to form press holds
2c which upward protrude, and press insertions 2e which downward
protrude. In each of the press holds 2c, the copper plate is bent
back at the apex so that two vertical copper plate portions are
opposed via a small gap therebetween. In each of the press
insertions 2e, the copper plate is bent back at the bottom so that
the gap between two inclined copper plate portions is gradually
increased to form a V-like section shape.
[0004] In the negative collector 2, as shown in FIG. 11, plural
edge portions of the negative electrode 1a protruding in the upper
end of the power generating element 1 are pressingly held in bundle
in each of the press holds 2c of the collector portion 2a and then
connected and fixed by crimping and ultrasonic welding. In this
case, the collector portion 2a is pressed down from the upper side
to the upper end portion of the power generating element 1, thereby
pressingly inserting the downward-protruding tip ends of the press
insertions 2e into gaps between the upper edge portions of the
negative electrode 1a. As a result, the upper edge portions of the
negative electrode 1a are distributed by the inclined faces on the
both sides of the V-like section shape, and then guided into the
gaps of the press holds 2c.
[0005] A positive collector 3 such as shown in FIG. 12 is disposed
on the lower end portion of the power generating element 1 so as to
perform current collection on the positive electrode 1b. The
positive collector 3 is structured in the same manner as the
negative collector 2, and has a collector portion 3a. However, the
positive collector consists of an aluminum plate in place of a
copper plate. In the positive collector 3, edge portions of the
positive electrode 1b protruding in the lower end of the power
generating element 1 are pressingly held in each of press holds 3c
of the collector portion 3a and then connected and fixed by
crimping and ultrasonic welding. In this case, similarly, the edge
portions of the positive electrode 1b are distributedly guided by
press insertions 3e into the gaps of the press holds 3c. In this
example, however, a terminal connector 3b is drawn out above the
upper end portion of the power generating element 1. In the case
where the positive terminal 5 is to protrude from a lower portion
of the power generating element 1, also the terminal connector 3b
is disposed below the lower end portion of the power generating
element 1.
[0006] For the sake of simplicity, in the figures, the negative
electrode 1a, the positive electrode 1b, and the like of the power
generating element 1 are shown so as to be wound coarsely or with a
reduced number of turns. In an actual case, they are wound very
closely or with a large number of turns, so that many edge portions
of the negative and positive electrodes 1a and 1b are pressingly
held in the gaps of the press holds 2c and 3c of the collector
portions 2a and 3a and then connected and fixed. In some case, the
collector portions 2a and 3a of the negative and positive
collectors 2 and 3 are disposed not only in one side with respect
to the center of the power generating element 1, but also above and
below the both sides with respect to the center, thereby improving
the current collecting efficiency.
[0007] In the negative and positive electrodes 1a and 1b of the
power generating element 1, however, very thin metal foils of
copper, aluminum, or the like are exposed in the upper and lower
edge portions. When the tip ends of the press insertions 2e and 3e
of the collector portions 2a and 3a are actually pressingly
inserted between the edge portions of the negative and positive
electrodes 1a and 1b, therefore, the tip ends catch the inclined
faces on the both sides of the V-like section shape, thereby
producing a problem in that the edge portions cannot be smoothly
guided into the gaps of the press holds 2c and 3c.
[0008] Since the press insertions 2e and 3e are disposed in the
collector portions 2a and 3a, the tip ends of the press insertions
2e and 3e are pushed into the power generating element 1.
Therefore, there arise further problems in that the tip ends may
make contact with the positive or negative electrode 1b or 1a which
is not subjected to current collection, to cause a short circuit,
and that the application area of the active material is narrowed
and hence the cell capacity is reduced. When the negative electrode
1a is to be connected and fixed to the press holds 2c of the
collector portion 2a, for example, the upper end of the positive
electrode 1b which is placed with being downward shifted approaches
the tip ends of the press insertions 2e as shown in FIG. 13.
Therefore, there arises a possibility that the upper end makes
contact with the tip end so as to cause a short circuit. In order
to prevent such a short circuit from occurring, the amount of shift
in each of the negative and positive electrodes 1a and 1b may be
increased. However, this causes the area where the active material
is not applied, to be widened. Consequently, the application area
is reduced by an area corresponding to the widened area, thereby
reducing the cell capacity.
[0009] The problem that the edge portions of the negative and
positive electrodes 1a and 1b cannot be smoothly inserted into the
gaps of the press holds 2c and 3c may be solved by employing the
following configuration. Comb-like jigs which are made of a
material of a low coefficient of friction and an excellent sliding
property are prepared so as to have elongated V-like teeth in which
the tip end is smaller in angle than the press insertions 2e and
3e. The jigs are pressed into the upper and lower end portions of
the power generating element 1 so that the upper and lower edge
portions of the negative and positive electrodes 1a and 1b are
previously distributed to positions respectively corresponding to
the gaps of the press holds 2c and 3c. Thereafter, the collector
portions 2a and 3a of the negative and positive collectors 2 and 3
are inserted thereinto. However, this countermeasure also cannot
solve the problems that the tip ends of the press insertions 2e and
3e may cause a short circuit, and that the application area of the
active material is narrowed.
SUMMARY OF THE INVENTION
[0010] The invention has been conducted in view of such
circumstances. It is an object of the invention to provide a cell
in which a press hold is directly disposed in a flat metal plate,
so that a short circuit with an electrode is prevented from
occurring and the application area of the active material can be
widened.
[0011] The cell of the invention of claim 1 is characterized in
that a collector portion of each of collectors comprises: plural
press holds in each of which two metal plate portions are projected
to be opposed via a gap that opens on a side of a basal portion, by
bending back a substantially vertical metal plate at an apex; and
flat plate portions which are formed by a flat metal plate portion
and through which adjacent ones of the press holds are coupled to
each other on the side of the basal portion, the collector portions
are respectively placed on ends of a winding axis of a wound type
power generating element, with respectively directing the basal
portions to the ends, the power generating element being configured
by winding strip positive and negative electrodes with a strip
separator therebetween with being mutually shifted in the winding
axis direction, and edge portions of the positive and negative
electrodes which protrude in the ends of the winding axis of the
power generating element are pressingly held in nearest press holds
of the collector portions to be connected and fixed.
[0012] According to the invention of claim 1, the plural press
holds which connect and fix the edge portions of the corresponding
electrode are coupled to one another through the flat plate
portions, and hence the portions are not pushed into the power
generating element. Consequently, the electrode which is not
connected and fixed by the press holds is prevented from making
contact with the collector portion to cause a short circuit. This
allows the amount of shift in winding of the positive and negative
electrodes, to be reduced. As a result, the area to which the
active material is applied can be widened so as to increase the
cell capacity.
[0013] The cell of the invention of claim 2 is characterized in
that the edge portions of the electrodes are inserted between the
two metal plate portions of the corresponding press hold of the
collector portions, and then connected and fixed to the two metal
plate portions by crimping and ultrasonic welding.
[0014] According to the invention of claim 2, the edge portions of
the electrodes can be surely connected and fixed to the press holds
of the collector portions by crimping and ultrasonic welding.
[0015] The cell of the invention of claim 3 is characterized in
that, in the cell of claim 1, a window is formed in a part of one
of the metal plate portions of each of the press holds of the
collector portions of the collectors, the window communicating with
the gap between the one metal plate portion and the other metal
plate portion.
[0016] According to the invention of claim 3, the window is formed
in a part of one of the metal plate portions of each press hold,
and hence the plural electrode edge portions which are pressingly
held in the press hold can be surely welded together so as to be
connected and fixed, by welding which is performed through the
window. The edge portions of the electrodes are exposed to one side
through the window. Therefore, welding is not restricted to that
based on vibration, such as ultrasonic welding, and may be
performed by directly applying heat, as in the case of laser
welding.
[0017] The cell of the invention of claim 4 is characterized in
that the edge portions of the electrodes of the cell of claim 3 are
connected and fixed by inserting the edge portions between the two
metal plate portions of the corresponding press hold of the
collector portions and then crimping the metal plate portions, and
also by ultrasonic welding of the window of the one metal plate
portion and the other metal plate portion, and a part of the one
metal plate portion other than the window and the other metal plate
portion.
[0018] According to the invention of claim 4, the plural electrode
edge portions which are pressingly held in the press hold can be
surely held between the part of the one metal plate portion other
than the window and the other metal plate portion, by crimping and
ultrasonic welding in the same manner as the prior art. Between the
one metal plate portion and the other metal plate portion, the
plural electrode edge portions are directly ultrasonic welded, and
hence surely welded together to be firmly connected and fixed.
[0019] The cell of the invention of claim 5 is a cell comprising: a
power generating element in which positive and negative electrode
plates are wound or laminated with a separator therebetween and an
edge portion of one of the electrode plates protrude from an edge
portion of another one of the electrode plates; and collectors
respectively connected to the edge portions, and characterized in
that each of the collectors is formed by bending a metal plate to
have plural groove portions which are used for pressingly holding
and bonding the edge portion of either of the electrode plates, and
a reduced thickness portion is formed in a part of each of the
groove portions
[0020] According to the invention of claim 5, the reduced thickness
portion is formed in a part of each of the metal plates which is
used for pressingly holding edge portions of the corresponding
electrode plate. Therefore, the plural electrode edge portions
which are pressingly held in the press hold can be surely melted
and welded so as to be connected and fixed by welding which is
performed through the reduced thickness portion. Both ends of the
electrode edge portions are pressingly held by the press holds.
Even when a certain external force is applied to the edge portions
during ultrasonic welding or after the production of the cell,
therefore, the electrode is not broken. As a result, it is possible
to attain excellent environmental resistant properties.
[0021] The cell of the invention of claim 6 is characterized in
that each of the collectors of the cell of claim 5 is formed by a
plate member of a thickness of 0.5 to 2 mm and the reduced
thickness portion has a thickness which is 10% to 80% of the
thickness of the collector.
[0022] When the thickness of the reduced thickness portion is
adjusted in the range specified in claim 6, welding is not
restricted to that based on vibration, such as ultrasonic welding,
and can be performed by applying heat through the reduced thickness
portion by means of laser welding or the like.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a perspective view showing a first embodiment of
the invention and showing a negative collector which is connected
and fixed to a power generating element;
[0024] FIG. 2 is a perspective view showing the first embodiment of
the invention and showing the configuration of the negative
collector and a positive collector which are to be connected and
fixed to the power generating element;
[0025] FIG. 3 is a perspective view showing the first embodiment of
the invention and showing jigs which are used for distributing edge
portions of a negative electrode which protrude from the upper end
of the power generating element;
[0026] FIG. 4 is a partial enlarged view showing the first
embodiment of the invention and showing a state where the edge
portions of the negative electrode are pressingly held by press
holds portions of a collector portion;
[0027] FIG. 5 is a perspective view showing a second embodiment of
the invention and showing a negative collector which is connected
and fixed to a power generating element;
[0028] FIG. 6 is a partial enlarged view showing the second
embodiment of the invention and enlargedly showing a collector
portion of the negative collector;
[0029] FIG. 7 is a perspective view showing a third embodiment of
the invention and showing a negative collector which is connected
and fixed to a power generating element;
[0030] FIG. 8 is a partial enlarged view showing the third
embodiment of the invention and enlargedly showing a collector
portion of the negative collector;
[0031] FIG. 9 is a perspective view showing the configuration of a
power generating element of a usual non-aqueous electrolyte
secondary cell;
[0032] FIG. 10 is a perspective view showing a prior art example
and showing the configuration of a negative collector which is to
be connected and fixed to a power generating element;
[0033] FIG. 11 is a perspective view showing the prior art example
and showing the negative collector which is connected and fixed to
the power generating element;
[0034] FIG. 12 is a perspective view showing the prior art example
and showing the configuration of the negative collector and a
positive collector which are to be connected and fixed to the power
generating element; and
[0035] FIG. 13 is a partial enlarged view showing the prior art
example and showing a state where edge portions of the negative
electrode are pressingly held by press holds of a collector
portion.
PREFERRED EMBODIMENTS OF THE INVENTION
[0036] Hereinafter, embodiments of the invention will be described
with reference to the accompanying drawings.
[0037] FIGS. 1 to 4 show a first embodiment of the invention. FIG.
1 is a perspective view showing a negative collector which is
connected and fixed to a power generating element, FIG. 2 is a
perspective view showing the configuration of the negative
collector and a positive collector which are to be connected and
fixed to the power generating element, FIG. 3 is a perspective view
showing jigs which are used for distributing edge portions of a
negative electrode which protrude from the upper end of the power
generating element, and FIG. 4 is a partial enlarged view showing a
state where the edge portions of the negative electrode are
pressingly held by press holds of a collector portion. The
components which have the same function as those of the prior art
shown in FIGS. 9 to 13 are denoted by the same reference
numerals.
[0038] The embodiment is a non-aqueous electrolyte secondary cell
which is useful in an electric vehicle and the like and which
comprises a power generating element 1 that is wound into an
elliptic cylindrical shape. In the same manner as shown in FIG. 9,
the power generating element 1 of the non-aqueous electrolyte
secondary cell is configured so that negative and positive
electrodes 1a and 1b are wound with being slightly shifted from
each other in the vertical direction (the direction of the winding
axis), thereby causing only upper edge portions of the negative
electrode 1a to protrude from the upper end of the power generating
element 1, and only lower edge portions of the positive electrode
1b to protrude from the lower end. The negative electrode 1a is
formed by applying a negative active material such as graphite to
the surface of a strip copper foil, and the positive electrode 1b
is formed by applying a positive active material such as a lithium
cobalt complex oxide to the surface of a strip aluminum foil. In
the negative electrode 1a, the negative active material is applied
only to a portion other than the upper edge portions, and, in the
positive electrode 1b, the positive active material is applied only
to a portion other than the lower edge portions. so that the copper
foil and the aluminum foil protrude from the upper and lower ends
of the power generating element 1 while the foils are exposed
therefrom, respectively. A strip microporous plastic film is used
as a separator 1c. The separator is wound so as to have a width at
which the portion where the negative and positive electrodes 1a and
1b overlap with each other is surely covered and the upper and
lower edge portions are not covered.
[0039] Negative and positive collectors 2 and 3 such as shown in
FIG. 2 are connected to the power generating element 1. The
negative collector 2 is formed by performing a press working on a
copper plate. A collector portion 2a is placed above one side with
respect to the center of the upper end portion of the power
generating element 1. In the collector portion 2a, a press hold 2c
is formed in three positions by bending the copper plate of the
negative collector 2, and a flat plate portion 2d is disposed
between adjacent ones of the press holds 2c. Each of the press
holds 2c is formed by upward bending the horizontal flat copper
plate and then folding back the plate at the apex so that two
copper plate portions are projected to be opposed to each other. A
gap that downward opens is formed between the two opposedly
protruding copper plate portions. Each of the flat plate portions
2d is a horizontal flat plate-like portion through which the lower
portions of adjacent ones of the press holds 2c are coupled to one
another, and is disposed in order to form a gap of a substantial
degree between the press holds 2c.
[0040] One end of the collector portion 2a of the negative
collector 2 is raised to a level which is equal to or higher than
the levels of the upper end portions of the press holds 2c, and
then drawn into a space above one semicircular area of the upper
end portion of the power generating element 1, to be coupled to a
horizontal flat plate-like terminal connector 2b. A lower end
portion of a negative terminal 4 is connected and fixed to the
terminal connector 2b by crimping. The positive collector 3 is
formed by performing a press working on an aluminum plate, and
configured in a similar manner as the negative collector 2. A
collector portion 3a is formed so as to be upside down. One end of
the collector portion 3a is drawn out along the side face of the
power generating element 1 to a space above the other semicircular
area of the upper end portion to be coupled to a horizontal flat
plate-like terminal connector 3b. A lower end portion of a positive
terminal 5 is connected and fixed to the terminal connector 3b by
crimping.
[0041] In the power generating element 1, as shown in FIG. 3, a
comb-like jig 6 in which downward-directed V-like teeth are formed
is first inserted into one side of the upper end portion with
respect to the center, thereby distributedly collecting edge
portions of the negative electrode 1a protruding in the upper end
of the power generating element 1, to three places. The jig 6 is
formed by using a material of high hardness such as high density
polyethylene, and the angle of the tip end of each tooth is made
small so that the V-like shape is elongated. As a result, the edge
portions of the negative electrode 1a can be smoothly distributed
without wrinkling or breaking the copper foil exposed in the edge
portions.
[0042] Next, as shown in FIG. 1, the negative collector 2 is placed
on the upper end portion of the power generating element 1, so that
the sets of plural edge portions of the negative electrode 1a which
have been distributed by the jig 6 are pressingly held in the gaps
of the press holds 2c of the collector portion 2a, respectively.
When the edge portions of the negative electrode 1a are once
pressingly held by the press holds 2c, the jig 6 is detached from
the power generating element. In each of the press holds 2c, the
two copper plate portions are crimped, and ultrasonic welding is
performed, whereby, in the edge portions of the negative electrode
1a which are pressingly held by the press hold 2c, the areas from
which the copper foil is exposed are connected and fixed to the
collector portion 2a. The crimping work is performed by inserting
an attachment of a crimping tool on the both sides of each of the
press holds 2c, from the upper side, and then applying a force so
as to collapse the two copper plate portions. The ultrasonic
welding is performed by inserting an attachment of an ultrasonic
welder on the both sides of each of the press holds 2c, from the
upper side, and then applying ultrasonic vibration to the two
copper plate portions. In order to form a space into which such an
attachment is to be inserted, between adjacent press holds 2c, the
flat plate portions 2d are disposed so as to form a gap of a
substantial degree between the press holds, as described above. For
the sake of simplicity, in the figures, the negative electrode 1a,
the positive electrode 1b, and the like of the power generating
element 1 are shown so as to be wound coarsely or with a reduced
number of turns. In an actual case, they are wound very closely or
with a large number of turns, so that many edge portions of the
negative electrode 1a are pressingly held in the gaps of the press
holds 2c of the collector portion 2a and then connected and
fixed.
[0043] In the positive collector 3 also, in the same manner as the
negative collector 2, plural edge portions of the positive
electrode 1b protruding in the lower end of the power generating
element 1 are pressingly held in bundle, in the area from which the
aluminum foil is exposed, in each of press holds 3c of the
collector portion 3a, and then connected and fixed by crimping and
ultrasonic welding. The terminal connector 3b of the positive
collector 3 which is drawn out from the collector portion 3a to the
upper end is overlappingly placed above the collector portion 2a of
the negative collector 2. An insulation member is inserted between
the collector portions so as to prevent a short circuit from
occurring.
[0044] The power generating element 1 in which the negative and
positive collectors 2 and 3 are connected and fixed as described
above is housed in a cell case (not shown) of an elliptic
cylindrical shape, a non-aqueous electrolyte solution is then
poured into the case, and the case is hermetically sealed, thereby
producing a non-aqueous electrolyte secondary cell. The negative
and positive terminals 4 and 5 are projected from the upper portion
of the cell with being insulatingly sealed.
[0045] According to this configuration, the plural press holds 2c
and 3c which are used for connecting and fixing the edge portions
of the negative and positive electrodes 1a and 1b are coupled to
one another via the flat plate portions 2d and 3d, respectively,
and the flat plate portions 2d and 3d are not pushed into the power
generating element 1. Therefore, there is no fear of a short
circuit, and the cell capacity can be increased. When the negative
electrode 1a is connected and fixed to the press holds 2c of the
collector portion 2a as shown in FIG. 4, for example, a
sufficiently large distance is maintained between the upper end of
the positive electrode 1b which is placed with being downward
shifted, and the rear faces of the flat plate portions 2d, and
hence there is no possibility that the electrode makes contact with
the flat plate portions to cause a short circuit. As far as the
upper end of the positive electrode 1b is sufficiently separated
from the rear faces of the flat plate portions 2d in this way,
there arises no fear of a short circuit even when the amount of
shift in each of the negative and positive electrodes 1a and 1b is
reduced. This enables the area where the active material is not
applied, to be narrowed, so that the application area is increased
by an area corresponding to the narrowed area, thereby increasing
the cell capacity. This is applicable also to the case where the
positive electrode 1b is connected and fixed to the press holds 3c
of the collector portion 3a.
[0046] Next, a second embodiment of the invention will be
described.
[0047] In the first embodiment, the very thin metal foils are
exposed in the edge portions of the negative and positive
electrodes 1a and 1b of the power generating element 1. By
contrast, the metal plates constituting the press holds 2c and 3c
of the collector portions 2a and 3a in the negative and positive
collectors 2 and 3 have a substantially large thickness, in order
to allow sufficiently large charging and discharging currents to
flow therethrough and hold the power generating element 1 in the
cell case. When ultrasonic welding is performed via the two thick
metal plate portions of each of the press holds 2c or 3c,
therefore, ultrasonic vibration may not be surely transmitted to
the large number of metal foils of the edge portions of the
negative or positive electrode 1a or 1b which are pressingly held
between the metal plate portions, and, particularly, metal foils in
the vicinity of the middle of the stack fail to be sufficiently
fusion bonded. This produces a problem in that the cell properties
may be lowered as the number of the charging and discharging cycles
of the cell is increased. When the power of ultrasonic welding is
increased so as to solve this problem, there arises a new problem
in that the edge portions of the negative or positive electrode 1a
or 1b which are formed by thin metal foils may be broken by strong
ultrasonic vibration. The second embodiment can solve this
problem.
[0048] FIGS. 5 and 6 show the second embodiment of the invention.
FIG. 5 is a perspective view showing a negative collector which is
connected and fixed to a power generating element, and FIG. 6 is a
partial enlarged view enlargedly showing a collector portion of the
negative collector.
[0049] A negative collector 2 such as shown in FIG. 5 is connected
to a negative electrode 1a of the power generating element 1. The
negative collector 2 is formed by a copper plate. A collector
portion 2a is formed above one side with respect to the center of
the upper end portion of the power generating element 1. A flat
plate-like terminal connector 2b is drawn out from the collector
portion 2a so as to be placed above one semicircular area of the
upper end portion of the power generating element 1. In the
collector portion 2a, a press hold 2c is formed in three positions
by bending the copper plate of the negative collector 2, and a flat
plate portion 2d is disposed between adjacent ones of the press
holds 2c. Each of the press holds 2c is formed by upward bending
the horizontal flat copper plate and then folding back the plate at
the apex so that two copper plate portions are projected to be
opposed to each other. A gap that downward opens is formed between
the two opposedly protruding copper plate portions. A window 2f is
formed in a part of one of the two copper plate portions. In the
embodiment, as shown in FIG. 6, the window 2f is formed in two
places of the one copper plate portion so as to leave the ends and
the center. The number and positions of the windows 2f may be
arbitrarily selected. Preferably, the windows 2f are formed so as
to occupy 10% to 80% of the total area of the one copper plate
portion. The configuration will be described in which the windows
2f are opened so as to elongate from the one copper plate portion
to the whole area of the apex formed by the copper plate portions,
in order to facilitate checking of the state of ultrasonic welding
that will be described later. It is not necessary to open the apex
also.
[0050] In the power generating element 1, the comb-like jig 6 (see
FIG. 3) in which downward-directed V-like teeth are formed is first
inserted into one side of the upper end portion with respect to the
center, thereby distributedly collecting edge portions of the
negative electrode 1a protruding in the upper end of the power
generating element 1, to three places. Next, as shown in FIG. 5,
the negative collector 2 is placed on the upper end portion of the
power generating element 1, so that the sets of plural edge
portions of the negative electrode 1a which have been distributed
by the jig 6 are pressingly held in the gaps of the press holds 2c
of the collector portion 2a, respectively. In each of the press
holds 2c, the part of the one copper plate portion other than the
windows 2f and the other copper plate portion are crimped. The
crimping work is performed by inserting an attachment of a crimping
tool on the both sides of each of the press holds 2c, from the
upper side, and then applying a force so as to collapse the two
copper plate portions. In each of the press holds 2c, as indicated
by the arrow A in FIG. 6, ultrasonic welding is performed between
the part of the one copper plate portion other than the windows 2f
and the other copper plate portion, and, as indicated by the arrow
B of FIG. 6, ultrasonic welding is performed also between the
windows 2f of the one copper plate portion and the other copper
plate portion. The ultrasonic welding is performed by inserting an
attachment of an ultrasonic welder on the both sides of each of the
press holds 2c, from the upper side, and then applying ultrasonic
vibration to the two copper plate portions. In the part of the one
copper plate portion other than the windows 2f and indicated by the
arrow A, the two thick copper plate portions are crimped and the
edge portions of the negative electrode 1a between the copper plate
portions are welded. Therefore, ultrasonic welding of a high power
is performed in the part. In the windows 2f of the one copper plate
portion and indicated by the arrow B, the thin copper foils of the
edge portions of the negative electrode 1a are directly welded, and
hence ultrasonic welding of a restricted power is performed.
[0051] In also the positive collector 3 which is not shown in FIG.
5, in the same manner as the negative collector 2, plural edge
portions of the positive electrode 1b protruding in the lower end
of the power generating element 1 are pressingly held in bundle, in
the area from which the aluminum foil is exposed, in each of press
holds 3c of the collector portion 3a, and then connected and fixed
by crimping and ultrasonic welding the part other than the windows
of the one aluminum plate portion, and ultrasonic welding the
windows of the one aluminum plate portion.
[0052] According to this configuration, the windows 2f are formed
in a part of one of the metal plate portions of each of the press
holds 2c and 3c of the collector portions 2a and 3a of the negative
and positive collectors 2. Therefore, the plural edge portions of
the negative and positive electrodes 1a and 1b which are pressingly
held by the press holds can be surely welded together so as to be
connected and fixed by ultrasonic welding which is directly
performed through the windows. Therefore, there is no fear that the
cell properties are lowered in accordance with the use of the cell.
Furthermore, also the part of one of the metal plate portions of
each of the press holds 2c and 3c other than the windows 2f can
surely hold the plural edge portions of the negative or positive
electrode 1a or 1b by means of crimping and ultrasonic welding.
[0053] Next, a third embodiment of the invention will be
described.
[0054] In the second embodiment, the windows 2f are formed in a
part of one of the two metal plate portions of each of the press
holds 2c of the collector portion 2a of the negative collector 2,
and the windows communicate with the gap between the one metal
plate portion and the other metal plate portion. When the plural
edge portions of the electrode which are pressingly held in the
press holds 2c are connected and fixed by performing welding
through the windows 2f, there arises a disadvantage that the foils
which are nearest to the windows are easily broken. The third
embodiment can solve this problem.
[0055] FIGS. 7 and 8 show the third embodiment of the invention.
FIG. 7 is a perspective view showing a negative collector which is
connected and fixed to a power generating element, and FIG. 8 is a
partial enlarged view enlargedly showing a collector portion of the
negative collector.
[0056] In the embodiment, a reduced thickness portion 2g is formed
in place of disposing the windows 2f of the second embodiment, in
the following manner.
[0057] The reduced thickness portion 2g is formed in a part of one
of the two copper plate portions of the negative collector 2. In
the embodiment, as shown in FIG. 8, the reduced thickness portion
2g is formed in two places of the one copper plate portion so as to
leave the ends and the center. The number and positions of the
reduced thickness portions 2g may be arbitrarily selected.
Preferably, the reduced thickness portions 2g are formed so as to
occupy 10% to 80% of the total area of the one copper plate
portion. The configuration will be described in which the reduced
thickness portions 2g are formed so as to elongate from the one
copper plate portion to the whole area of the apex formed by the
copper plate portions, in order to facilitate checking of the state
of ultrasonic welding that will be described later. It is not
necessary to form the reduced thickness portions also in the
apex.
[0058] Preferably, the negative collector 2 is formed by a plate
member of a thickness of 0.5 to 2 mm and the reduced thickness
portions 2g have a thickness which is 10% to 80% of the thickness
of the collector. When the thickness is adjusted so as to have such
a value, welding is not restricted to that based on vibration, such
as ultrasonic welding, and can be performed by applying heat
through the reduced thickness portions 2g by means of laser welding
or the like.
[0059] In the power generating element 1, the comb-like jig 6 (see
FIG. 3) in which downward-directed V-like teeth are formed is first
inserted into one side of the upper end portion with respect to the
center, thereby distributedly collecting edge portions of the
negative electrode 1a protruding in the upper end of the power
generating element 1, to three places. Next, as shown in FIG. 7,
the negative collector 2 is placed on the upper end portion of the
power generating element 1, so that the sets of plural edge
portions of the negative electrode 1a which have been distributed
by the jig 6 are pressingly held in the gaps of the press holds 2c
of the collector portion 2a, respectively. In each of the press
holds 2c, the part of the one copper plate portion other than the
reduced thickness portions 2g and the other copper plate portion
are crimped. The crimping work is performed by inserting an
attachment of a crimping tool on the both sides of each of the
press holds 2c, from the upper side, and then applying a force so
as to collapse the two copper plate portions. In each of the press
holds 2c, as indicated by the arrow A in FIG. 8, ultrasonic welding
is performed between the part of the one copper plate portion other
than the reduced thickness portions 2g and the other copper plate
portion, and, as indicated by the arrow B of FIG. 8, ultrasonic
welding is performed also between the reduced thickness portions 2g
of the one copper plate portion and the other copper plate portion.
The ultrasonic welding is performed by inserting an attachment of
an ultrasonic welder on the both sides of each of the press holds
2c, from the upper side, and then applying ultrasonic vibration to
the two copper plate portions. In the part of the one copper plate
portion other than the reduced thickness portions 2g and indicated
by the arrow A, the two thick copper plate portions are crimped and
the edge portions of the negative electrode 1a between the copper
plate portions are welded. Therefore, ultrasonic welding of a high
power is performed in the part. In the reduced thickness portions
2g of the one copper plate portion and indicated by the arrow B,
the thin copper foils of the edge portions of the negative
electrode 1a are directly welded, and hence ultrasonic welding of a
restricted power is performed.
[0060] In also the positive collector 3 which is not shown in FIG.
7, in the same manner as the negative collector 2, plural edge
portions of the positive electrode 1b protruding in the lower end
of the power generating element 1 are pressingly held in bundle, in
the area from which the aluminum foil is exposed, in each of press
holds 3c of the collector portion 3a, and then connected and fixed
by crimping and ultrasonic welding the part other than the reduced
thickness portions of the one aluminum plate portion, and
ultrasonic welding the reduced thickness portions of the one
aluminum plate portion.
[0061] According to this configuration, the reduced thickness
portions 2g are formed in a part of one of the metal plate portions
of each of the press holds 2c and 3c of the collector portions 2a
and 3a of the negative and positive collectors 2. Therefore, the
plural edge portions of the negative and positive electrodes 1a and
1b which are pressingly held by the press holds can be surely
welded together so as to be connected and fixed by ultrasonic
welding which is directly performed through the reduced thickness
portions 2g. Therefore, there is no fear that the cell properties
are lowered in accordance with the use of the cell. Furthermore,
also the part of one of the metal plate portions of each of the
press holds 2c and 3c other than the reduced thickness portions 2g
can surely hold the plural edge portions of the negative or
positive electrode 1a or 1b by means of crimping and ultrasonic
welding.
[0062] In the embodiments described above, the power generating
element 1 is wound into an elliptic cylindrical shape. The
invention may be similarly applied also on a wound type power
generating element of another kind. In the case of a cylindrical
power generating element, for example, the press holds 2c and 3c of
the collector portions 2a and 3a must be formed so as to be curved
along the winding of the negative and positive electrodes 1a and
1b.
[0063] In the embodiments, description has been made on a
non-aqueous electrolyte secondary cell. The invention may be
implemented also on a usual cell of another kind. In the
embodiments, the negative and positive electrodes 1a and 1b are
formed by copper and aluminum plates, respectively. Depending on
the kind of the cell, a metal plate of another kind may be
used.
[0064] In the embodiments, the press holds 2c and 3c of the
negative and positive collectors 2 and 3 are crimped and then
ultrasonic welded. The invention is not restricted to this method
as far as the edge portions of the negative and positive electrodes
1a and 1b can be pressingly held so as to be fixed and connected.
For example, laser welding or the like may be used.
[0065] As apparent from the above description, according to the
cell of the invention, the flat plate portions are formed among the
plural press holds of the collector portion of each of the
collectors, and hence there is no fear that the portions are pushed
into the power generating element and make contact with another
electrode to cause a short circuit. This allows the amount of shift
in winding of the positive and negative electrodes, to be reduced.
As a result, the area to which the active material is applied can
be widened so as to increase the cell capacity.
[0066] According to the cell of the invention, the window is formed
in a part of one of the metal plate portions of each press hold,
and hence the plural electrode edge portions which are pressingly
held in the press hold can be surely welded together so as to be
connected and fixed by welding which is performed through the
window. Therefore, there is no fear that the cell properties are
lowered in accordance with the use of the cell because of
insufficient electrical connection.
[0067] According to the cell of the invention, the reduced
thickness portion is formed in a part of one of the metal plate
portions of each press hold, and hence the plural electrode edge
portions which are pressingly held in the press hold can be surely
welded together so as to be connected and fixed by welding which is
performed through the reduced thickness portion. Therefore, there
is no fear that the cell properties are lowered in accordance with
the use of the cell because of insufficient electrical
connection.
* * * * *