Title: Prismatic sealed battery module
Abstract: A prismatic sealed battery module includes: a prismatic battery case; an electrode plate group constituted by alternately layering positive and negative electrode plates with a separator arranged therebetween; and an electrolyte. The positive or negative electrode plates protruding from each end face of the electrode plate group are bonded to a collector member. A metal connector is fixed to the central part of the collector member facing the inner surface of the side end wall of the battery case. The collector member is connected, at the metal connector, to an external terminal using an externally connecting bolt.
Patent Number: 7,022,432 Issued on 04/04/2006 to Asahina, et al.
| Inventors:
|
Asahina; Takashi (Toyohashi, JP);
Hamada; Shinji (Toyohashi, JP);
Fukuda; Shinsuke (Moriguchi, JP);
Eto; Toyohiko (Toyota, JP)
|
| Assignee:
|
Matsushita Electric Industrial Co., Ltd. (Osaka, JP);
Toyota Jidosha Kabushiki Kaisha (Aichi, JP)
|
| Appl. No.:
|
213799 |
| Filed:
|
August 6, 2002 |
Foreign Application Priority Data
| Aug 06, 2001[JP] | 2001-237752 |
| Current U.S. Class: |
429/179; 429/153; 429/181 |
| Current Intern'l Class: |
H01M 2/02 (20060101); H01M 2/30 (20060101) |
| Field of Search: |
429/153,178,179,181
|
References Cited [Referenced By]
U.S. Patent Documents
| 4150201 | Apr., 1979 | Silveyra.
| |
| 4882242 | Nov., 1989 | Kilb et al.
| |
| 5302473 | Apr., 1994 | Bennett.
| |
| Foreign Patent Documents |
| 0 962 993 | Dec., 1999 | EP.
| |
| 1 087 449 | Mar., 2001 | EP.
| |
| 1 096 582 | May., 2001 | EP.
| |
| 1 211 739 | Jun., 2002 | EP.
| |
| 1 098 879 | Aug., 1955 | FR.
| |
| 790025 | Jan., 1958 | GB.
| |
| 59-108264 | Jun., 1984 | JP.
| |
| 2001/-093503 | Apr., 2001 | JP.
| |
| 2001/-093508 | Apr., 2001 | JP.
| |
| 2002093402 | Mar., 2002 | JP.
| |
| 2002231214 | Aug., 2002 | JP.
| |
Primary Examiner: Cantelmo; Gregg
Attorney, Agent or Firm: Jordan and Hamburg LLP
Claims
What is claimed is:
1. A prismatic sealed battery module comprising:
electrode plate groups each constituted by alternately layering positive and
negative electrode plates with a separator interposed therebetween;
an electrolyte;
a prismatic battery case for accommodating the electrode plate groups and the electrolyte;
the positive or negative electrode plates protruding from an end face of at least
one of the electrode plate groups being bonded to a first collector member,
an external terminal connected to a central part of the first collector member
facing an inner surface of a side end wall of the battery case,
said electrode plate groups having side edges;
a second collector member directly contacting and connecting the side edges of
adjacent ones of the electrode plate groups, said second collector member being
located between said side edges to serve as both a collector member and a partition
wall between said adjacent electrode plate groups and provide a current path limited
to a space between said side edges of said adjacent electrode plate groups.
2. The prismatic sealed battery module according to claim 1, further comprising:
the prismatic battery case having a plurality of prismatic cell cases with the
second collector member forming a common wall between two of said prismatic cell
cases, each of said electrode plate groups being disposed within each of the cell
cases; and
another external terminal being connected to a central part of a third collector
member facing an inner surface of another side end wall of the battery case at
an opposing end from the external terminal of the prismatic battery case.
3. The prismatic sealed battery module according to claim 1, wherein the collector
member extends substantially the entire length of side edges of adjacent electrode
plate groups.
4. The prismatic sealed battery module according to claim 1, wherein said electrode
plate groups comprise side edges and a single collector member connects the side
edges of adjacent electrode plate groups.
5. The prismatic sealed battery module according to claim 1, wherein said electrode
plate groups comprise side edges and a collector member connects the side edges
of adjacent electrode plate groups such that no additional connection is necessary
to electrically connect the electrode plate groups.
6. The prismatic sealed battery module according to claim 1, wherein the collector
member is corrugated.
7. The prismatic sealed battery module according to claim 1, wherein an end of
the collector member is fluid-tightly bonded to a side wall of the prismatic battery case.
8. The prismatic sealed battery according to claim 1, wherein said current path
has a length equal to a distance between said side edges of said adjacent electrode
plate groups.
9. A prismatic sealed battery module comprising:
at least one electrode plate group constituted by alternately layering positive
and negative electrode plates with a separator interposed therebetween;
an electrolyte; and
a prismatic battery case for accommodating the at least one electrode plate group
and the electrolyte, wherein
the positive or negative electrode plates protruding from both end faces of the
at least one electrode plate group are bonded to a collector member,
an external terminal is connected to a central part of the collector member facing
an inner surface of a side end wall of the prismatic battery case,
a metal connector is fixed to the central part of the collector member facing
the inner surface of the side end wall,
a sealing material is arranged at an outer periphery of a contact surface between
the metal connector and the inner surface of the side end wall, and
an externally connecting bolt is fastened through the side end wall to the metal connector.
10. The prismatic sealed battery module according to claim 9, wherein the external
terminal is fixed to a connection plate which is arranged on an outer surface of
the side end wall of the battery case and is fastened thereto by the externally
connecting bolt.
11. The prismatic sealed battery module according to claim 9, wherein the externally
connecting bolt is provided with the external terminal.
12. The prismatic sealed battery module according to claim 9, further comprising:
an externally connection plate having a substantially L-shaped cross-sectional
profile, which includes a fitting portion and a connecting portion adjoining thereto,
the fitting portion making contact with an outer surface of the side end wall of
the battery case, and the connecting portion making contact with an end of a longer
side surface of the battery case, wherein
the fitting portion of the externally connection plate is fastened down by the
externally connecting bolt, so that interconnection between juxtaposed prismatic
sealed battery modules is effected by bringing their connecting portions into contact
with each other.
13. The prismatic sealed battery module according to claim 12, further comprising
a U-shaped elastic portion arranged at a bend of the externally connection plate
between the fitting portion and connecting portion.
14. The prismatic sealed battery module according to claim 12, wherein a press-contact
projection is protrudingly formed in the connecting portion of the externally connection plate.
Description
The present disclosure relates to subject matter contained in priority Japanese
Patent Application No. 2001-237752, filed on Aug. 6, 2001, the contents of which
is herein expressly incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a prismatic sealed battery module, and more
particularly to a prismatic sealed battery module which succeeds in reducing connection
resistance with respect to an external terminal.
2. Description of Related Art
A conventional rechargeable battery module is typically composed of a plurality
of cells connected together to obtain a desired electric power capacity. Such a
rechargeable battery module is constructed by stackingly arranging a plurality
of prismatic cells such that longer side surfaces of battery cases are arranged
opposite each other, followed by placing an end plate outside the battery case
of each endmost cell, further followed by binding them together with a tie band.
In the rechargeable battery module, each of the cells is connected, via a lead
extended upward from an upper end of its electrode plate, to an external terminal
attached to a cover of the battery case. Then, the external terminals are connected
with each other by connection plates, thus effecting interconnection between the cells.
In this conventional construction, due to the complexity of interconnection between
the cells, a large number of constitution parts are required. Moreover, the connection
paths between the cells are long and the connection points are large in number.
This leads to an undesirable increase in the cost. In addition, occurrence of unduly
large part resistance makes it difficult to improve power output and service life
characteristics in the rechargeable battery module.
In light of the foregoing, the present applicant has previously proposed a prismatic
sealed battery module 101 shown in FIG. 5 that incorporates a plurality
of cells 102. In the figure, the reference numeral 103 denotes a
prismatic battery case. The prismatic battery case 103 is formed in the
shape of a flat prism by integrally and contiguously arranging prismatic battery
cases 104 of the cells 102 with a shorter side surface and a longer
side surface, each of whose shorter side surfaces is common to adjacent such battery
cases as a partition wall 105. Upper openings of the battery cases 104
are sealed with an integrally-formed cover 106. Connection holes 107
are formed outside the shorter side surface of each endmost battery case 104
and in the upper part of the partition wall 105 between adjacent battery
cases 104.
The battery cases 104 each accommodate an electrolyte and an electrode
plate group 108 formed by layering rectangular positive and negative electrode
plates with a separator interposed therebetween. Thereby, the cell 102 is
realized. Part of the positive and negative electrode plates of the electrode plate
group 108 extend sideways in mutually different directions, so as to form
leads 109
a and 109
b. The leads 109
a and
109
b of the positive and negative electrode plates have their edges
connected to collector plates 110
a and 110
b, respectively,
by welding or other means.
At an upper part of the collector plate 110
a, 110
b is
protrudingly formed a connecting projection 111 which is fitted in the connection
hole 107. Interconnection between adjacent battery cases 104 is effected
by connecting together the connecting projections 111 of the positive/negative
collector plates 110
a and 110
b by welding. Fitted in
the connection hole 107 formed on the outer shorter side surface of the
endmost battery case 104 is a positive or negative external terminal 112,
whose connecting projection 113 is connected to the connecting projection
111 of the collector plate 110
a or 110
b by welding.
In this way, a plurality of the cells 102 accommodated in the prismatic
battery case 103 are connected in series with each other, so that power
output is produced between the endmost external terminals 112.
However, the construction shown in FIG. 5 has the following disadvantage.
Although a current-carrying path from the positive or negative electrode plate,
through its respective lead 109
a or 109
b, to the collector
plate 110
a or 110
b can be made short, in order to complete
the current-carrying path between the collector plate and the external terminal
112, current must take a path reaching the upper end of the collector plate
110
a, 110
b first, and then pass through a welding point
between the two front ends of the connecting projection 111 of the upper
end and the connecting projection 113 of the external terminal 112.
Consequently, the length of the entire current-carrying path becomes unduly long,
and also the connection resistance is increased because of the necessity of energizing
a portion having a small sectional area, giving rise to a-great loss induced by
electrical connection resistance.
Another problems with the construction are that: since interconnection between
the cells 102 is effected by weld-connecting together the front ends of
the connecting projections 111 respectively formed at the upper ends of
the collector plates 110
a and 110
b, the connection
path must be made to take a detour, resulting in an increase in the length of the
connection path; since the weld-connection is made only at one point, the resistance
is increased; using the collector plates 110
a and 110
b
leads to an increase in the cost; and the collector plates 110
a and
110
b are arranged on both sides of the electrode plate group 108,
and their upper parts need to be so formed as to extend beyond the upper end of
the electrode plate group 108, resulting in an increase in the volume of
the battery case 104.
SUMMARY OF THE INVENTION
The present invention has been devised in light of the above-mentioned problems
with the conventional art, and accordingly an object of the present invention is
to provide a prismatic sealed battery module in which connection resistance between
an electrode plate group and an external terminal is suppressed to reduce a loss
induced by electrical connection resistance.
To achieve the above object, according to one aspect of the present invention,
there is provided a prismatic sealed battery module including: a prismatic battery
case; an electrode plate group constituted by alternately layering positive and
negative electrode plates with a separator interposed therebetween; and an electrolyte,
wherein the positive or negative electrode plates protruding from both end faces
of the electrode plate group are bonded to a collector member, and the collector
member, which faces an inner surface of a side end wall of the battery case, has
its central part connected to an external terminal. With this construction, a current-carrying
path from each portion of the electrode plate to the collector member is made short,
and the collector member has its central part connected to an external terminal.
This helps suppress the connection resistance with respect to the external terminal,
and thus a loss induced by electrical connection resistance is reduced.
According to another aspect of the invention, there is provided a prismatic
sealed battery module including a prismatic battery case consisting of a plurality
of prismatic cell cases, and the electrode plate group is disposed within each
of the cell cases. Moreover, the electrode plates included in the electrode plate
group are bonded to the collector member constituting at least part of a partition
wall between adjacent cell cases, and the collector member, which faces the inner
surface of the side end wall of the cell case at each end of the prismatic battery
case, has its central part connected to the external terminal. With this construction,
interconnection between the cells, of which each is constituted by disposing an
electrode plate group in a cell case, is effected by directly connecting together
the electrode plates of their electrode plate groups via the collector member.
This makes it possible to obtain a short and straight connection path and thus
reduce the connection resistance. Moreover, since the collector member constitutes
part of the partition wall, no collector member is additionally provided. This
makes cost reduction possible. Further, since there is no need to secure a space
above the electrode plate group for establishing connection, the cell case is made
smaller in volume, and thus the volumetric efficiency is improved.
According to still another aspect of the invention, there is provided a
prismatic sealed battery module which includes an externally connection plate having
a substantially L-shaped cross-sectional profile, which includes a fitting portion
and a connecting portion adjoining thereto, the fitting portion making contact
with the outer surface of the side end wall of the cell case, and the connecting
portion making contact with an end of a longer side of the cell case. The fitting
portion of the externally connection plate is fastened down by an externally connecting
bolt, so that interconnection between the juxtaposed prismatic sealed battery modules
is effected by bringing their connecting portions into contact with each other.
With this construction, the externally connection plate functions as an external
terminal, and thus prismatic sealed battery modules are connected together simply
by being juxtaposed and bound together. Since there is no need to use a part for
providing connection between the battery modules, such as a bus bar module, the
number of constitution parts is reduced and also connecting operation becomes unnecessary.
Consequently, both cost reduction and miniaturization are achieved.
While novel features of the invention are set forth in the preceding, the invention,
both as to organization and content, can be further understood and appreciated,
along with other objects and features thereof, from the following detailed description
and examples when taken in conjunction with the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1A and 1B are views showing a prismatic sealed battery module according
to a first embodiment of the present invention, with FIG. 1A being a partial longitudinal
sectional view, and FIG. 1B being a side view;
FIGS. 2A and 2B are views showing a prismatic sealed battery module according
to a second embodiment of the invention, with FIG. 2A being a partial longitudinal
sectional view, and FIG. 2B being a side view;
FIGS. 3A and 3B are views showing a prismatic sealed battery module according
to a third embodiment of the invention, with FIG. 3A being a partial longitudinal
sectional view, and FIG. 3B being a side view;
FIGS. 4A and 4B are views showing the structure of a principal portion of the
third embodiment, with FIG. 4A being an enlarged horizontal sectional plan view,
and FIG. 4B being a horizontal sectional plan view of an externally connection
plate in an unconnected state; and
FIG. 5 is a partial longitudinal sectional view of a prismatic sealed battery
module of a conventional example.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
First Embodiment
Hereinafter, a first embodiment of a prismatic sealed battery module
according to the present invention will be described with reference to FIGS. 1A
and 1B.
In FIGS. 1A and 1B, a prismatic sealed battery module
1 of the first embodiment
incorporates a plurality of cells
2 made of nickel-metal hydride rechargeable
batteries. The reference numeral
3 denotes a prismatic battery case, which
is formed in the shape of a flat prism by juxtaposing prismatic cell cases
4
with a shorter side surface and a longer side surface, each of whose shorter side
surfaces is common to adjacent such cell cases. An upper opening of the prismatic
battery case
3 is sealed with an integrally-formed cover
6. The cell
2 is constituted by housing in the cell case
4 an electrolyte and
an electrode plate group
8 formed by layering rectangular positive and negative
electrode plates with a separator interposed therebetween. Part of the positive
and negative electrode plates of the electrode plate group
8 extend sideways
in mutually different directions so as to form leads
9a and
9b.
Between the adjacent cell cases
4 and inside the shorter-side wall
of each end of the prismatic battery case
3 are disposed collector members
16 each formed by folding an electrically conductive plate material in a
corrugated shape (refer to FIG. 4A). After inserting the leads
9a and
9b of the positive and negative electrode plates into each concavely-curved
part of the corrugation of the collector member
16, the corrugation is caulked
and compressed, thus connecting the positive and negative electrode plates to the
collector member
16.
The collector member
16 has its lengthwise ends fluid-tightly bonded,
via a sealing material such as a pitch, to the side walls of the prismatic battery
case
3, and also has its upper and lower ends integrally bonded to sealing
partition materials
17 made of rubber or the like. The upper sealing partition
material
17 is fluid-tightly bonded, via a sealing material such as a pitch,
to a ceiling surface of the cover
6, and similarly the lower sealing partition
material
17 is fluid-tightly bonded via a sealing material to an inner bottom
surface of the prismatic battery case
3. In this way, the collector member
16 provides part of the partition wall between the adjacent cell cases
4,
so that a plurality of the cells
2 housed in the prismatic battery case
3 are connected in series with one another via the collector members
16
constituting part of the partition wall.
In the manufacturing process, a predetermined number of electrode plate groups
8 are connected together via the collector members
16, and the assembly
is intactly arranged in the prismatic battery case
3. Then, each end of
the collector member
16 is fluid-tightly bonded to the side wall of the
prismatic battery case
3, thus constituting the cell case
4 in which
the electrode plate group
8 is arranged.
The electrode plate group
8 is constituted by alternately arranging a
plurality of positive and negative electrode plates. More specifically, the positive
electrode plates are each covered with a bag-like separator having an opening in
the lateral direction, so that the positive and negative electrode plates are layered
together with the separator interposed therebetween. The positive electrode plate,
apart from the lead
9a, is formed by filling nickel hydroxide in
Ni foamed metal. The lead
9a is formed by compressing foamed metal
under pressure, and its one surface is seam-welded to a lead plate by ultrasonic
welding. The negative electrode plate, apart from the lead
9b, is
formed by coating a negative electrode material containing hydrogen-absorption
alloy on Ni punched metal.
To the central part of the collector member
16, facing the inner surface
of a side end wall
3a of the prismatic battery case
3, is
fixed a metal connector
18 with a weld portion
19. The metal connector
18 has a screw hole
20 formed at its end face facing the side end
wall
3a. The side end wall
3a has a bolt hole
21
formed concentrically with the screw hole
20. Around the screw hole
20
is disposed an O ring
22, acting as a sealing material, to secure fluid
tightness. On the outer surface of the side end wall
3a is arranged
a connection plate
24 to which a plate
25a for mounting an
external terminal
25 is fixed with a spot weld portion
26. An externally
connecting bolt
23, penetrating through the connection plate
24 and
the bolt hole
21, is threadedly engaged in the screw hole
20, thus
allowing the connection plate
24 to be fastened to the side end wall
3a.
According to the prismatic sealed battery module
1 thus constructed,
in each of the cells
2, the electrode plates are connected together by disposing
the collector member
16 at each end of the electrode plate group
8.
This arrangement helps reduce the length of the current-carrying path from each
electrode plate to the collecting member
16. Moreover, the connection is
established by inserting the leads
9a and
9b into each
concavely-curved part of the corrugated collector member
16, followed by
caulking. This makes it possible to increase the contact area of the connecting
portions, and thereby obtain a highly reliable connection condition and reduce
the connection resistance. Further, interconnection between the cells
2
is effected by directly connecting together the electrode plates of the electrode
plate group
8 via the collector member
16. This makes it possible
to obtain a short and straight connection path, to increase the connection area,
to reduce the connection resistance, and to suppress the internal resistance.
The collector member
16 constitutes part of the partition wall between
the adjacent cell cases
4. This eliminates the need to additionally provide
a collector member, and thus makes cost reduction possible. Moreover, since there
is no need to secure a space above the electrode plate group
8 for providing
connection between the cells
2, the cell case
4 is made smaller in
volume, and thus the volumetric efficiency is improved.
The collector member
16 and the external terminal
25 are connected
together as follows. Firstly, the metal connector
18 is welded to the central
part of the collector member
16 facing the inner surface of the side end
wall
3a of the prismatic battery case
3. Thereafter, the connection
plate
24, to which the external terminal
25 is attached, is arranged
on the outer surface of the side end wall
3a. Subsequently, the connection
plate
24 is fastened to the metal connector
18 using the externally
connecting bolt
23. With this procedure, a sufficiently large current-carrying
area is provided in the connecting portion and thus the connection resistance is
reduced. Hence, a loss induced by electrical connection resistance is suppressed.
Since the external terminal
25 is provided independently of the externally
connecting bolt
23 by means of the connection plate
24, the external
terminals
25 of the prismatic sealed battery modules
1, juxtaposed
as shown in FIG. 1B, are connected together without adversely affecting the junction
between the externally connecting bolt
23 and the collector member
16.
Hence, a highly reliable connection condition is achieved.
Second Embodiment
Next, a second embodiment of the prismatic sealed battery module according
to the invention will be described with reference to FIGS. 2A and 2B. Note that,
in the descriptions connected to the second embodiment, such elements as are found
also in the previous embodiment are identified with the same reference numerals
and symbols, and the descriptions thereof will be omitted. That is, only the points
of difference will be described below.
In this embodiment, instead of the externally connecting bolt
23 of the
first embodiment, an externally connecting bolt
27 is used that is provided
integrally with a concentrically-formed external terminal
25.
According to the second embodiment, there is no need to additionally provide
the connection plate
24, to which the external terminal
25 is fixed,
as used in the first embodiment. Thus, the number of constitution parts is reduced,
thereby making cost reduction possible.
Third Embodiment
Next, a third embodiment of the prismatic sealed battery module according to
the invention will be described with reference to FIGS. 3A through 4B.
In this embodiment, instead of the connection plate
24 of the first embodiment
with the external terminal
25 attached to it, there is provided an externally
connection plate
28 having a substantially L-shaped cross-sectional profile.
As shown in FIGS. 3A through 4B, the external connection plate
28 includes
a fitting portion
29 and a connecting portion
30 adjoining thereto.
The fitting portion
29 makes contact with the outer surface of the side
end wall
3a of the prismatic battery case
3, and the connecting
portion
30 makes contact with the end of the longer side of the prismatic
battery case
3. The fitting portion
29 is fastened to the metal connector
18 with the externally connecting bolt
23. In a bend between the
fitting portion
29 and the connecting portion
30 is provided a U-shaped
elastic portion
31. As shown in FIG. 4B, the connecting portion
30
has a press-contact projection
32 formed so as to protrude toward the outer surface.
According to the third embodiment, as shown in FIGS. 3B and 4A, a plurality
of prismatic sealed battery modules
1 are connected together simply by being
juxtaposed and bound together in the juxtaposition direction, because the connecting
portions
30 of the externally connection plates
28 are brought into
contact with each other. Thus, there is no need to prepare a part for providing
connection between the external terminals
25, such as a bus bar module,
and the connecting operation becomes unnecessary. Consequently, both cost reduction
and miniaturization are achieved.
Moreover, the U-shaped elastic portion
31 is provided between the
fitting portion
29 and connecting portion
30 of the externally connection
plate
28. Since this U-shaped elastic portion
31 serves to absorb
the dimensional tolerance of the prismatic battery case
3 or the externally
connection plate
28, a stable connection condition is ensured. In addition,
since the press-contact projection
32 is protrudingly formed in the connecting
portion
30, it is possible to ensure that the connecting portions
30
are kept press-contacted to each other. Consequently, the connection resistance
is suppressed stably.
The embodiments described hereinabove exemplify the prismatic sealed battery
module
1 of the type that incorporates a plurality of cells
2 and
in which the cells
2 are directly connected together via the collector member
16 constituting part of the partition wall between the adjacent cell cases
4 of the cells
2. Alternatively, even if the prismatic sealed battery
module
1 is composed of a single cell, by applying the present invention,
the connection resistance between the electrode plate group and the external terminal
is suppressed. Moreover, a collector member in use is not limited to the corrugated
collector member
16, but may be of a collector member shaped like a flat
plate. In this case, the lead
9a or
9b of each electrode
plate of the electrode plate group
8 may be connected to the collector member
by bonding using solder or an electrically conductive adhesive, or by press contacting,
or by resistance welding in a press-contacted state. It is also possible to employ
such a structure that the electrode plate group
8 has its side ends each
bonded to the collector member and these collector members are bonded together.
As described heretofore, according to the prismatic sealed battery module embodying
the present invention, the positive or negative electrode plate, protruding from
each end face of the electrode plate group, is bonded to the collector member,
and the external terminal is connected to the central part of the collector member
facing the inner surface of the side end wall of the battery case. Thus, the current-carrying
path from each portion of the electrode plate to the collector member is made short.
Moreover, since the external terminal is connected to the central part of the collector
member, the connection resistance with respect to the external terminal is reduced.
Hence, a loss induced by electrical connection resistance is successfully suppressed.
Further, there is provided the prismatic sealed battery module including
the prismatic battery case composed of a plurality of prismatic cell cases. The
electrode plates of the electrode plate group within each cell case is bonded to
the collector member constituting at least part of the partition wall between the
adjacent cell cases, and the external terminal is connected to the central part
of the collector member facing the inner surface of the side end wall of the cell
case at each end of the prismatic battery case. Thereupon, interconnection between
the cells is effected by directly connecting together the electrode plates of their
electrode plate groups via the collector member. This makes it possible to obtain
a short and straight connection path and thus reduce the connection resistance.
Moreover, the collector member constitutes part of the partition wall, and this
eliminates the need to additionally provide a collector member. Thus, cost reduction
is achieved. Further, since there is no need to secure a space above the electrode
plate group for providing connection, the cell case is made smaller in volume,
and thus the volumetric efficiency is improved.
Although the present invention has been fully described in connection with
the preferred embodiment thereof, it is to be noted that various changes and modifications
apparent to those skilled in the art are to be understood as included within the
scope of the present invention as defined by the appended claims unless they depart therefrom.
*
