U.S. patent application number 09/843637 was filed with the patent office on 2002-01-17 for combined battery.
Invention is credited to Eto, Toyohiko, Iwase, Masayoshi, Marukawa, Shuhei, Miki, Takahiko, Watanabe, Ko, Yamauchi, Tomokazu.
Application Number | 20020006545 09/843637 |
Document ID | / |
Family ID | 18640593 |
Filed Date | 2002-01-17 |
United States Patent
Application |
20020006545 |
Kind Code |
A1 |
Marukawa, Shuhei ; et
al. |
January 17, 2002 |
Combined battery
Abstract
The combined battery of the present invention includes two end
plates and a plurality of general cells stacked adjacent each other
and bound by two end plates. The general cells are provided with a
battery container made of resin, and bound by two end plates with a
binding force equal to or lower than a threshold value determined
based on the number and the compressibility of the cells and the
stiffness of the battery container, in such a manner that no more
than a predetermined amount of irreversible deformation will be
caused in the battery container.
Inventors: |
Marukawa, Shuhei; (Aichi,
JP) ; Watanabe, Ko; (Aichi, JP) ; Eto,
Toyohiko; (Aichi, JP) ; Iwase, Masayoshi;
(Aichi, JP) ; Yamauchi, Tomokazu; (Aichi, JP)
; Miki, Takahiko; (Aichi, JP) |
Correspondence
Address: |
MERCHANT & GOULD PC
P.O. BOX 2903
MINNEAPOLIS
MN
55402-0903
US
|
Family ID: |
18640593 |
Appl. No.: |
09/843637 |
Filed: |
April 26, 2001 |
Current U.S.
Class: |
429/156 ;
429/176 |
Current CPC
Class: |
H01M 10/613 20150401;
H01M 50/227 20210101; H01M 10/647 20150401; H01M 10/6551 20150401;
H01M 50/20 20210101; H01M 50/209 20210101; H01M 50/116 20210101;
Y10T 29/49108 20150115; H01M 50/278 20210101; H01M 50/258 20210101;
Y02E 60/10 20130101; H01M 10/6557 20150401 |
Class at
Publication: |
429/156 ;
429/176 |
International
Class: |
H01M 002/02; H01M
002/10 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 28, 2000 |
JP |
2000-131758 |
Claims
What is claimed is:
1. A combined battery comprising two end plates and a plurality of
cells stacked adjacent each other and bound by the two end plates,
wherein the cells are provided with a battery container made of
resin, and the plurality of cells are bound by the two end plates
with a binding force equal to or lower than a threshold value
determined based on a number and a compressibility of the cells and
stiffness of the battery container, in such a manner that no more
than a predetermined amount of irreversible deformation will be
caused in the battery container.
2. A combined battery according to claim 1, wherein the cell
includes an electrode plate group containing positive electrode
plates and negative electrode plates stacked adjacent each other
with separators interposed therebetween, and the cells are stacked
in a direction corresponding to a stacking direction of the
electrode plate group.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a combined battery
including a plurality of cells.
[0003] 2. Description of the Related Art In recent years, secondary
cells have come into wide use even in equipment requiring a high
capacity and a high voltage. Such equipment uses a combined battery
in which a number of secondary cells are connected in series or in
parallel. Examples of the combined battery include those of the
monoblock type, which accommodate a plurality of electrode plate
groups in one battery container, and those of binding type in which
a plurality of cells (secondary cells) are bound by using end
plates or binding bands. If there are about 10 electrode plate
groups, the monoblock type is effective because of its satisfactory
volumetric efficiency. However, in the case of constructing a
combined battery by using 10 or more electrode plate groups,
cooling efficiency will decrease.
[0004] On the other hand, according to the binding type, by forming
convex portions such as ribs on a battery container or placing a
spacer between battery containers, cooling efficiency can be
enhanced. Furthermore, even in the case where one of the cells has
a defect, only the defective cell needs to be exchanged. Thus, the
binding type is excellent in working efficiency.
[0005] However, in the combined battery of the conventional binding
type, when the battery container of one cell expands, the
surrounding normal cells receive a load generated by the expansion,
which may deform the battery container irreversibly. In particular,
when convex portions are not formed on side surfaces of the battery
container on which an electrode plate group is disposed, the
battery container is likely to expand due to the expansion of the
electrode plate group, and the battery container may be deformed
irreversibly.
SUMMARY OF THE INVENTION
[0006] Therefore, with the foregoing in mind, it is an object of
the present invention to provide a combined battery capable of
suppressing irreversible deformation of a battery container to no
more than a predetermined amount.
[0007] In order to achieve the above-mentioned object, the combined
battery of the present invention includes two end plates and a
plurality of cells stacked adjacent each other and bound by the two
end plates, wherein the cells are provided with a battery container
made of resin, and the plurality of cells are bound by the two end
plates with a binding force equal to or lower than a threshold
value determined based on a number and a compressibility of the
cells and stiffness of the battery container, in such a manner that
no more than a predetermined amount of irreversible deformation
will be caused in the battery container. Because of the
above-mentioned structure, a combined battery is obtained that can
suppress irreversible deformation in the battery container to no
more than a predetermined amount. In the present specification, the
term "cell" includes a "unit cell".
[0008] In the above-mentioned combined battery, it is preferable
that the cell includes an electrode plate group containing positive
electrode plates and negative electrode plates stacked adjacent
each other with separators interposed therebetween, and the cells
are stacked in the direction of the stacking direction of the
electrode plate group.
[0009] These and other advantages of the present invention will
become apparent to those skilled in the art upon reading and
understanding the following detailed description with reference to
the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a perspective view showing an exemplary combined
battery of the present invention.
[0011] FIG. 2 is a perspective view showing an exemplary unit cell
used in the combined battery of the present invention.
[0012] FIG. 3 is a partial cross-sectional view of the unit cell in
FIG. 2.
[0013] FIG. 4 is a partial cross-sectional view of the unit cell in
FIG. 2.
[0014] FIGS. 5A and 5B illustrate the relationship between the load
and the cell width.
[0015] FIGS. 6A and 6B illustrate the relationship between the load
and the cell width.
[0016] FIGS. 7A and 7B illustrate the relationship between the load
and the cell width.
[0017] FIGS. 8A and 8B illustrate the relationship between the load
and the cell width.
[0018] FIG. 9 illustrates the relationship between the load and the
cell width.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] Hereinafter, the present invention will be described by way
of illustrative embodiment with reference to the drawings.
[0020] FIG. 1 shows an exemplary combined battery 10 of the present
invention. Referring to FIG. 1, the combined battery 10 includes a
plurality of stacked unit cells 20, two end plates 11 disposed at
both ends of the stacked unit cells 20 in a stacking direction, and
binding bands 12 disposed so as to connect two end plates 11.
[0021] The end plate 11 is made of, for example, a metal plate such
as stainless steel and nickel-plated iron. The binding band 12 is
made of a plate or a bar of the same material as that of the end
plate 11.
[0022] FIG. 2 shows a perspective view of the unit cell 20.
Referring to FIG. 2, the unit cell 20 includes an integrated
battery container 22 covered with a lid 21, an electrode terminal
23 disposed on the integrated battery container 22, and safety
valves 24 disposed on the lid 21.
[0023] The lid 21 and the integrated battery container 22 are made
of resin such as polypropylene (PP), polyphenylene ether (PPE), or
ABS.
[0024] The integrated battery container 22 has a plurality of ribs
25 placed at a predetermined interval on each side surface 22a with
the largest area among those of the battery container 22. The ribs
25 are formed at positions corresponding to partition walls 31 of
the unit cell shown in FIG. 3, and each rib 25 has substantially
the same height from the side surface 22a. The lid 21 and the
integrated battery container 22 have a plurality of convex portions
26 at a border between the lid 21 and the integrated battery
container 22 on the side surface 22a. The integrated battery
container 22 includes a plurality of convex portions 27 on the side
surface 22a. The ribs 25, and the convex portions 26 and 27 come
into contact with an adjacent unit cell 20 in the combined battery
10. The ribs 25, and the convex portions 26 and 27 (in particular,
ribs 25) function to transmit a load given by the end plates 11 to
the adjacent unit cell 20. Furthermore, the ribs 25, and the convex
portions 26 and 27 function to easily cool the unit cell 20 by
forming a space between the adjacent unit cells 20.
[0025] FIG. 3 shows a cross-sectional view of the combined battery
10 in a direction parallel to the side surface 22a of the
integrated battery container 22. The unit cell 20 includes a
plurality of battery containers 32 partitioned by a plurality of
partition walls 31 in the integrated battery container 22. The ribs
25 are formed at positions corresponding to the partition walls 31.
In each battery container 32, an electrode plate group 33 and an
electrolyte (not shown) are disposed, and each battery container 32
constitutes a cell. The partition walls 31 extend from the bottom
surface of the integrated battery container 22 to the vicinity of
the lid 21.
[0026] FIG. 4 shows a cross-sectional view of the electrode plate
group 33 taken along line A-A in FIG. 3. Referring to FIG. 4, the
electrode plate group 33 includes a plurality of positive electrode
plates 35 and a plurality of negative electrode plates 36 stacked
adjacent each other with separators 34 interposed therebetween. As
shown in FIG. 4, the positive electrode plates 35 and the negative
electrode plates 36 are disposed in a direction parallel to the
side surface 22a. More specifically, in the electrode plate group
33, the positive electrode plates 35 and the negative electrode
plates 36 are stacked adjacent each other in a direction vertical
to the side surface 22a. As the positive electrode plates 35 and
the negative electrode plates 36, those which are used for a
general secondary cell can be used, respectively. For example, a
positive electrode plate containing nickel and a negative electrode
plate containing a hydrogen-storing alloy can be used.
[0027] As described above, in the combined battery 10, a plurality
of unit cells 20 are stacked adjacent each other so that the
adjacent unit cells 20 are opposed at the side surface 22a, and
bound and fixed by the end plates 11 and the binding bands 12. The
end plates 11 are disposed at both ends of the stacked unit cells
20, and bound by the binding bands 12. The unit cells 20 are
stacked in a direction corresponding to a direction in which the
positive electrode plates 35 and the negative electrode plates 36
are stacked.
[0028] The internal pressure of a cell is increased due to
overcharge and overdischarge. In the case where the internal
pressure of a plurality of cells is increased simultaneously, loads
thereof cancel each other, whereby the cells maintain an initial
binding size. However, in the case where the internal pressure of
only several cells among a plurality of cells is increased, only
the cells with their internal pressure increased expand, and
compress other cells whose internal pressure is not increased. As a
result, the expanded cells further expand. Furthermore, the
integrated battery container 22 has an expansion limit. When
expansion exceeding the limit occurs, irreversible deformation is
caused in the integrated battery container 22. As factors
influencing the expansion of the integrated battery container 22,
the number of unit cells 20 to be bound, the compressibility of the
unit cells 20, the stiffness of the integrated battery container
22, and the internal pressure of a cell can be considered. The
internal pressure of a cell mainly is determined in terms of the
performance of a cell. Therefore, it is difficult to handle the
internal pressure of a cell as a factor for controlling the
expansion of a cell. Thus, the remaining three factors are required
to be controlled so that the expansion of a cell becomes equal to
or lower than the limit. Hereinafter, the influence of varying the
number of unit cells 20 to be bound, the compressibility of the
unit cells 20, and the stiffness of the integrated battery
container 22 will be described in this order.
[0029] First, the influence of varying the number of unit cells 20
will be described. FIG. 5A schematically shows the case where one
unit cell 20 is interposed between two end plates 11. Herein, it is
assumed that a width S of the unit cell 20 before binding (distance
between the highest portion of the ribs 25 formed on one side
surface 22a and the highest portion of the ribs 25 formed on the
other side surface 22a) is 19.8 mm. FIG. 5B shows a relationship
between a load F applied to the unit cell 20 by the end plates 11
and the width S of the unit cell 20. Hereinafter, a curve
representing the relationship between the load F and the width S
may be referred to as an F-S curve. As shown in FIG. 5B, when the
load F is varied, the width S is changed.
[0030] FIG. 6A schematically shows the case where a unit cell 20a
and a unit cell 20b are interposed between two end plates 11. The
unit cells 20a and 20b are similar to the unit cell 20. It is
assumed that the width S of the unit cell 20a before binding is
19.65 mm, and that of the unit cell 20b before binding is 19.8 mm.
In FIG. 6A, the unit cells 20a and 20b are bound to each other so
that the distance between two end plates 11 becomes 39 mm. At this
time, each width S of the bound unit cells 20a and 20b can be
obtained by using the F-S curves of the unit cells 20a and 20b. The
F-S curve of the unit cell 20a and the F-S curve of the unit cell
20b are represented by (a) and (b) in FIG. 6B. In FIG. 6B, the
horizontal axes of the F-S curves are reversed between the unit
cells 20a and 20b so that the total of the width S of the unit cell
20a and the width S of the unit cell 20b becomes 39 mm (19.5
mm.times.2). In FIG. 6B, a crossing point between the F-S curves of
the unit cells 20a and 20b corresponds to a balance position P
where the loads of both the unit cells are matched with each other.
It is understood from FIG. 6B that after binding, the width S of
the unit cell 20a becomes 19.4 mm, and the width S of the unit cell
20b becomes 19.6 mm. Herein, when the width S of the unit cell 20
exceeds the limit of a predetermined amount of irreversible
deformation of the integrated battery container 22, the
predetermined amount of irreversible deformation is caused in the
integrated battery container 22. Therefore, by prescribing the
balance position P so that the width S does not exceed the limit of
a predetermined amount of irreversible deformation of the
integrated battery container 22, the predetermined amount of
irreversible deformation of the integrated battery container 22 can
be prevented. The balance position P can be changed by varying a
binding force. As described above, in the combined battery 10, each
cell can be bound with a binding force equal to or lower than a
threshold value at which a predetermined amount of irreversible
deformation is not caused in the integrated battery container
22.
[0031] FIG. 7A schematically shows the case where unit cells 20c,
20d, and 20e are interposed between two end plates 11. The unit
cells 20c to 20e are similar to the unit cell 20. Herein, it is
assumed that the width S of the unit cells 20c and 20d before
binding is 19.65 mm, and the width S of the unit cell 20e before
binding is 19.8 mm. In FIG. 7A, the unit cells 20c to 20e are bound
to each other so that the distance between two end plates 11
becomes 58.5 mm (19.5 mm.times.3). In this case, the unit cells 20c
and 20d are compressed by the same amount. Therefore, the F-S curve
of a virtual unit cell 20cd (combination of the unit cells 20c and
20d) has a horizontal axis which is twice that of the F-S curve of
the unit cell 20c. The F-S curves of the unit cell 20c, the virtual
unit cell 20cd, and the unit cell 20e are represented by (c) and
(d), (cd), and (e) in FIG. 7B. As is apparent from FIG. 7B, the
width S of the unit cell 20e (which is larger than those of the
other cells; hereinafter, which may be referred to as an "expanded
cell") at the balance position P becomes larger, compared with the
case where two unit cells 20 are bound. In this manner, by varying
the number of cells to be bound, the expansion coefficient of the
expanded cell at the balance position P can be changed. For
example, by decreasing the number of cells to be bound, the width S
of the expanded cell at the balance position P can be decreased.
Thus, a predetermined amount of irreversible deformation can be
prevented in the integrated battery cell 22.
[0032] Next, the influence of varying the compressibility of a cell
will be described. FIG. 8A shows the F-S curves of the unit cells
20a and 20b described with reference to FIG. 6. In FIG. 8A, (a-1)
represents an initial F-S curve of the unit cell 20a, (a-2)
represents an F-S curve in which the compressibility of a cell is
increased, and (a-3) represents an F-S curve in which the
compressibility of a cell is further increased. Furthermore, in
FIG. 8A, (b) represents the F-S curve of the unit cell 20b. As
shown in FIG. 8A, by varying the compressibility of a cell, the
slope of the F-S curve can be changed. More specifically, by
varying the compressibility of the unit cells 20 to be bound, the
width S of the unit cell 20 at the balance position P can be
changed. Similarly, even in the case where the number of unit cells
20 to be bound is 3 or more, the slope of the F-S curve can be
changed by varying the compressibility of the unit cell 20. FIG. 8B
shows F-S curves in the case where three unit cells are bound. In
FIG. 8B, (cd-1) represents an initial F-S curve of the virtual unit
cell 20cd described in FIGS. 7A and 7B. As the unit cell 20cd is
compressed, the F-S curve changes to (cd-2) and (cd-3).
[0033] Next, the influence of varying the stiffness of the
integrated battery container 22 will be described. The load applied
to the unit cell 20 is classified into a load from the electrode
plate groups 33 and a load from the integrated battery container
22. FIG. 9 schematically shows a relationship between each load and
the F-S curve. Herein, it is difficult to change F-S
characteristics of the electrode plate groups, depending upon the
design of a cell. However, the load from the integrated battery
container 22 can be controlled. In order to vary the stiffness of
the integrated battery container 22, the height of the partition
walls 31 (height from the bottom surface of the battery container
32 to the lid 21), the thickness of the partition walls 31, the
material of the integrated battery container 22 (Young's modulus of
the integrated battery container 22), or the like can be changed.
By varying the stiffness of the integrated battery container 22,
the width S of the unit cell at the balance position P can be
changed. For example, when the stiffness of the integrated battery
container 22 is increased, the slope of the F-S curve is increased,
and the width S of the expanded cell at the balance position P is
decreased.
[0034] In the combined battery 10 of the present invention, the
maximum binding force (threshold value A) is obtained that does not
generate the predetermined amount of deformation in the integrated
battery container 22, considering the above-mentioned factors, and
the unit cells 20 are bound to each other with a binding force
equal to or lower than the threshold value A. Thus, in the combined
battery 10 of the present invention, the predetermined amount of
irreversible deformation can be prevented in the integrated battery
container 22.
[0035] According to another aspect, the present invention relates
to a method for designing (or producing) a combined battery. More
specifically, according to the method for designing a combined
battery of the present invention, a binding force, the distance
between two end plates, the number of unit cells, the
compressibility of the unit cell, and the stiffness of the
integrated battery container are varied so that the width S of the
unit cell at the balance position P does not exceed the limit of a
predetermined amount of irreversible deformation of the integrated
battery container, based on the F-S curves of the unit cells to be
bound.
[0036] In the above-mentioned embodiment, the case has been
described where the cells to be bound are unit cells with a
plurality of cells (provided with only one electrode plate group).
However, cells may be bound.
[0037] As described above, according to the present invention, a
combined battery is obtained that can prevent a predetermined
amount of irreversible deformation in a battery container.
[0038] The invention may be embodied in other forms without
departing from the spirit or essential characteristics thereof. The
embodiments disclosed in this application are to be considered in
all respects as illustrative and not limiting. The scope of the
invention is indicated by the appended claims rather than by the
foregoing description, and all changes which come within the
meaning and range of equivalency of the claims are intended to be
embraced therein.
* * * * *