JPH0745258A - Secondary battery jar - Google Patents

Abstract

PURPOSE:To provide a secondary battery jar in which improving volumetric energy density can be realized to facilitate manufacture. CONSTITUTION:Cell chambers c1 to c10 aligned in a line are formed by partitioning the inside of an outer case 1 by internal partitions 12. Battery cells 2 of the same shape are stored one by one each other in the cell chambers c1 to c10, to laminate positive and negative poles of each battery cell 2 in a battery cell arranging direction. Here, a laminating directional width of the cell chambers c1, c10 in the end part is formed larger than a laminating directional width of the cell chamber c2 to c9 in the central part and further smaller than a maximum value of the laminating directional width in an unlocked condition of each battery cell 2. In the battery cells 2 in both ends, by a charge, since the laminating directional width of the cell chambers c1, c10 is relatively large formed, when expanded a little in a laminating direction, a wall part 11a of the outer case 11 and internal partitions 12a, 12i in the outermost side hold pressing force, mainly in a laminating directional outside of the battery cell 2, carried. Thus without reinforcing the wall part 11a of the outer case 11, laminating directional dimension of the battery jar is contracted, and volumetric energy density can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery case for a secondary battery in which three or more battery cells in which a sheet-shaped positive electrode and a negative electrode are laminated with a separator interposed therebetween are arranged in series.

[0002]

2. Description of the Related Art An example of a conventional secondary battery is shown in FIG. The battery case 1 is composed of an outer case 11 made of a resin and inner partition walls 12 that are parallel to each other and partition the inside of the outer case 11 into a large number of cell chambers c. Each cell chamber c includes a hydrogen secondary battery. The cells 2 are individually housed. Each battery cell 2 is formed by stacking positive and negative electrodes via a separator, and the stacking direction of the positive and negative electrodes is aligned with the arrangement direction of the battery cells 2.

Here, since the width of the battery cell 2 in the stacking direction (hereinafter referred to as the stacking direction width) becomes maximum at the completion of charging due to the increase in volume due to charging, the maximum value of the stacking direction width of the battery cell 2 at the completion of charging. W (with unrestricted charging)
The dimension Wc of each cell chamber c in the stacking direction is determined in consideration of max, and thereby the stress applied to the wall portion 11a of the outer box 11 is reduced. For example, Wc is set to a maximum value Wmax of the width of the battery cells 2 in the stacking direction.

In Japanese Patent Laid-Open No. 2-306533, in order to prevent the wall portion of the outer box from expanding due to an increase in the width of each battery cell in the stacking direction, a high-strength reinforcing plate that is insert-molded is used. Reinforcing the walls of the box is disclosed. In addition, it has been proposed that the battery case be sandwiched between a pair of holding plates in the stacking direction and both holding plates be fastened with a belt or long bolts.

[0005]

However, when the dimension Wc in the stacking direction of each cell chamber c is determined to be large in advance in consideration of the increase in the volume of the battery cell 2, the dimension in the stacking direction of the outer box 11 increases, and The problem is that the volumetric energy density is reduced accordingly. Usually, the width in the stacking direction of the battery cell 2 made of a hydrogen secondary battery changes 1.5 times before and after charging under an unrestrained state, that is, under the condition that displacement in the stacking direction is not regulated.

Further, in the technique of the above publication, the reinforcing plate is generally a metal plate, but as a result, there is a fear that a short circuit will occur between the battery cell and the reinforcing plate, and the outer box will not be manufactured. It gets complicated. Furthermore, when using a restraint plate, a belt or long bolts, the volume energy density is reduced by the amount of the restraint plate,
Moreover, the assembling process and the structure are complicated.

The present invention has been made in view of the above problems, and it is an object to be solved to provide a battery case for a secondary battery which can realize an improvement in volumetric energy density and is easy to manufacture. .

[0008]

A battery case for a secondary battery according to the present invention comprises a rectangular outer box having electrical insulation properties, a periphery of which is fixed to the rectangular box, and the inside of the rectangular box is divided into three or more. In the battery case of the secondary battery, which has parallel plate-like internal partition walls that form the cell chambers in a row in parallel with each other and individually accommodates the battery cells of the same shape in each cell chamber, and is located at the end portion in the stacking direction. The width of the cell chamber in the stacking direction is larger than the width of the cell chamber in the center part in the stacking direction and smaller than the width of the battery cell in the stacking direction at the time of maximum expansion in the unrestrained state.

[0009]

The inner partition wall divides the inside of the outer box to form three or more cell chambers arranged in a line. Battery cells of the same shape are housed in each cell chamber, and the positive and negative electrodes of each battery cell are stacked in the battery cell array direction. Here, the width of the end cell chamber in the stacking direction is set to be larger than the width of the center cell chamber in the stacking direction and smaller than the maximum value of the stacking direction width of each battery cell in the unrestrained state.

Although a detailed description will be given later, a brief description will be given. Although the battery cells at both ends have a relatively large width in the stacking direction of the cell chambers due to charging, they slightly expand in the stacking direction. Is smaller than the maximum width of the battery cells in the stacking direction, the expansion of the battery cells at both ends is partly suppressed, and to that extent, the wall part of the outer box is outwardly in the stacking direction and the outermost inner partition wall is inwardly in the stacking direction. , Push with the first force.

On the other hand, since the remaining battery cells are accommodated in a narrower cell chamber, the expansion in the stacking direction due to charging is further restricted, and as a result, these remaining battery cells have the internal partition walls in contact with each other in the stacking direction. Push with a second force stronger than the above first force. As a result, the wall portion of the outer box is pushed outward by the first force in the stacking direction, and the outermost inner partition wall is pushed outward by the difference between the first force and the second force in the stacking direction. The partition wall is pushed by the second force from both sides, and eventually the wall portion of the outer box is bent outward by the first force in the stacking direction, and the outermost inner partition wall is stacked by the difference between the first force and the second force. Bend outward in the direction.

[0012]

As described above, in the battery case of the secondary battery of the present invention, the width of the end cell chamber in the stacking direction is larger than the width of the center cell chamber in the stacking direction, and Since it is set to be smaller than the width in the stacking direction at the time of maximum expansion in the restrained state, the dimension in the stacking direction of the battery case can be shortened and the volume energy density can be improved.

Further, since the pressure applied to the wall portion of the outer box as the cell chamber is reduced is shared by the outermost inner partition wall,
It is not necessary to reinforce the wall of the outer box, and the manufacturing process can be simplified.

[0014]

EXAMPLE A schematic cross-sectional view of a hydrogen secondary battery adopting the battery case of the present invention is shown in FIG. This battery includes a prismatic battery case 1, a battery cell 2 housed in the battery case 1, a positive electrode terminal 3 and a negative electrode terminal 4 provided in the battery case 1, and the positive and negative electrodes of each battery cell 2 are connected. (Not shown) are connected in series, the positive electrode (not shown) of the rightmost battery cell 2 is electrically connected to the positive electrode terminal 3, and the negative electrode (not shown) of the leftmost battery cell 2 is electrically connected to the negative electrode terminal 4. Has been done.

The battery case 1 is composed of a rectangular outer box 11 made of an electrically insulating resin and eight parallel inner sections which divide the inside of the outer box 11 into ten cell chambers c1 to c10 arranged in a line. Comprising partition walls 12a to 12i, each cell chamber c1 to c10
The battery cells 2 made of hydrogen secondary batteries are individually housed therein. The width in the stacking direction of the cell chambers c1 and c10 at both ends is 30.
mm, the width in the stacking direction of the remaining eight cell chambers c2 to c9 is 20
mm, the thickness of the wall portion 11a of the outer box 11 is 2 mm, and the thickness of the inner partition walls 12a to 12i is 2 mm.

The battery case 1 is actually manufactured as follows. First, a box portion having an upper opening formed by integrally molding the wall portion 11a, the bottom portion 11b, and the internal partition walls 12a to 12i of the outer box 11,
A flat lid 11c having parallel slits into which the internal partition walls 12a to 12i can be fitted is prepared, and the battery cells 2 and electrical connection members (not shown) for various electrical connections are housed in the box portion. 11 c is covered on the upper end opening of the box portion, the internal partition walls 12 a to 12 i are individually fitted into the parallel slits of the flat lid, and the necessary portions are welded, whereby the sealed battery case 1 is formed. Therefore, the outer box 11 has a closed rectangular box shape, and the entire peripheral edges of the inner partition walls 12a to 12i are the wall portion 11a, the bottom portion 11b, and the flat lid 11c of the outer box 11.
It is fixed to.

Each battery cell 2 has a positive and negative electrode (not shown) and an ion-permeable and electrically insulating separator (not shown).
The positive and negative electrodes are stacked with the battery cells 2 arranged in the same direction. Battery cell 2 is
The width of the battery cell 2 in the stacking direction before being housed in the battery case 1 is about 20 mm,
The width in the stacking direction immediately after the completion of charging is about 30 mm.
More specifically, the positive electrode was formed by using an expanded metal made of nickel as a current collector and press-bonding nickel hydroxide paste thereto. The negative electrode is MmNi
A hydrogen storage alloy powder having a composition of _3.5 Co _0.7 Al _0.8 is mechanically made into a powder of 100 mesh or less, and electroless copper plating is performed using a commercially available plating solution so that the plating amount becomes 20% of the total amount. 1.3g to 25g of plating alloy powder
PTFE dispersion (D-1 manufactured by Daikin Industries, Ltd.) was added, kneaded, and preformed into a sheet shape, and then 300 degrees Celsius on both surfaces of the nickel expanded metal.
The pressure is 300 kg / cm ² . Each of the positive and negative electrodes was wound with a separator (not shown) made of polypropylene nonwoven fabric sandwiched therebetween to produce each battery cell 2.

[0018] Prepared as described above and using a 5N KOH + 1N LiOH aqueous solution as an electrolyte, a nominal 100A
A prismatic battery pack of h and 12 V was manufactured. Hereinafter, the function and effect that characterize the present embodiment will be described. When the negative electrode occludes hydrogen by charging, each battery cell 2 tries to expand. When the battery cell 2 is unrestrained, its volume increases due to free expansion, and when it is pressurized by a strong external force, the voids inside the negative electrode decrease and the volume hardly increases, and it is pressurized by a weak external force. Then, the voids inside the negative electrode are slightly reduced and the volume is also slightly increased. After all, the increase in the volume of the battery cell 2 after charging has a positive correlation with the applied pressure.

In this embodiment, since the battery cells 2 at both ends are accommodated in the cell chambers c1 and c10 having a relatively large width in the stacking direction, the battery cells 2 expand in the stacking direction, and this expansion causes the outer case 11 to expand.
11a is pushed outward by the force f1 in the stacking direction, the outermost inner partition walls 12a, 12i are pushed inward by the force f1 in the stacking direction, and the wall 11a of the outer box 11 pushes the abutting battery cell 2 in the stacking direction. Push inward with force f1 to balance the forces.

On the other hand, the above-mentioned outermost internal partition wall 12a,
Focusing on 12i, the outermost inner partition walls 12a, 1
2i is pushed from the outermost battery cells 2 inward in the stacking direction by force f1 as described above, and the cell chambers c2, c9
The battery cell 2 is pushed outward by the force f2 in the stacking direction. Since the width of the cell chambers c2 and c9 in the stacking direction is smaller than that of the cell chambers c1 and c10, the force f2 is larger than the force f1. Therefore, the inner partition walls 12a and 12i are deformed outward due to the force difference f2-f1 in the stacking direction.
a and 12i are forces f2 to the inner battery cell 2 inward in the stacking direction.
-Press f1 to balance the force. Internal partition 12a, 1
The cell chambers c2 to c9 are slightly expanded by the deformation of 2i to the outside in the stacking direction, so that the width of the battery cells 2 in the cell chambers c2 to c9 in the stacking direction is slightly increased.

Next, paying attention to the inner partition walls 12b and 12h, the inner partition walls 12b and 12h are pushed by the force f2 from the outer battery cells 2 toward the inner side in the stacking direction and the cell chamber c.
It is pushed by the force f3 from the battery cells 3 and c8 to the outside in the stacking direction. Since the cell chambers c2 and c9 are slightly deformed outward in the stacking direction as described above, the force f2 is slightly smaller than the force f3, and as a result, the internal partition walls 12b and 12h are also slightly deformed outward in the stacking direction.

Similarly, the inner partition walls 12c to 12g are slightly deformed outward in the stacking direction, but the remaining inner partition walls 12c.
The deformation of ~ 12g is small and can be ignored. As a result, the internal partition walls 12c to 12g are pressed from the battery cells 2 on both sides after charging to the opposite sides in the stacking direction with almost equal force, and as a result, the stacking of the battery cells 2 in the remaining cell chambers c3 to c8 is performed. The direction width hardly increases.

On the other hand, the cell chambers c2 and c9 have internal partition walls 12
When a and 12i are deformed outward in the stacking direction, they are widened in the stacking direction, and eventually the inner partition walls 12a and 12i and the wall portion 11a of the outer box 11 mainly carry the pressing force in the stacking direction of the battery cells 2. Therefore, in this embodiment, all the above forces are applied to the outer case 1.
It is possible to prevent it from hanging on the wall portion 11a of No. 1 and to reduce the dimension in the stacking direction of the battery case 1 without reinforcing the wall portion 11a of the outer box 11. (Test) The volume energy density and the weight energy density of the battery of the above example and the batteries of the following comparative examples 1 and 2 were examined.

However, Comparative Example 1 is the battery of Example 1 in which the width of each cell chamber c in the stacking direction is 30 mm. In Comparative Example 2, in the battery of Example 1, the width of each cell chamber c in the stacking direction was set to 20 mm, the outer box 11 was further sandwiched from both sides in the stacking direction by ABS resin plates having a thickness of 15 mm, and these ABS resin plates were separated by a belt. It has been concluded. As shown in FIGS. 2 and 3, it was found that the battery of this example was the best in terms of volume energy density and weight energy density. (Modification) In the above embodiment, only the outermost cell chamber c in each cell chamber c is expanded in the stacking direction, but the outermost cell chamber c is expanded in the stacking direction width toward the inner cell chamber c. If they are gradually reduced, a difference occurs in the pressing force in the stacking direction between the outer battery cells 2 and the inner battery cells 2 sandwiching any internal partition wall 12,
As a result, each internal partition wall 12 and the wall portion 11a of the outer box 11 share and carry the pressing force outward in the stacking direction of the battery cells 2, and the above-mentioned pressing force to the wall portion 11a of the outer box 11 is held. It is possible to prevent concentration and also to prevent concentration of the pressing force on some of the internal partition walls 12.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention,

2 is a characteristic diagram showing test results of the battery of FIG. 1,

FIG. 3 is a characteristic diagram showing test results of the battery of FIG.

FIG. 4 is a cross-sectional view of a conventional battery,

[Explanation of symbols]

1 is a battery case, 2 is a battery cell, 11 is an outer box, 11a is a wall of the outer box, 12 is an internal partition wall, c is a cell chamber,

Claims (1)

[Claims] 1. A rectangular outer box having electrical insulation, a peripheral portion of which is fixed to the rectangular box and a partitioning inside the rectangular box.
Positioned at the end in the stacking direction in the battery case of a secondary battery that has parallel plate-like internal partition walls that form the above-mentioned cell chambers in a row and individually accommodates the same-shaped battery cells in each cell chamber. The width in the stacking direction of the cell chamber is larger than the width in the stacking direction of the cell chamber at the central portion in the stacking direction and smaller than the width in the stacking direction at the time of maximum expansion of the battery cells in the unrestrained state. Rechargeable battery case.