JP2022010534A - Battery module - Google Patents

Abstract

To provide a battery module capable of providing a desired large restraint load.SOLUTION: The battery module includes a restraint member 9, which connects a pair of end plates 7, 8 and restrains single batteries 10 in a stacking direction, a pair of wedge members 30 disposed between the single batteries 10 and applying a restraint load, and a strain member 60, which is disposed between the pair of wedge members 30 and applies a restraint load by transverse strain caused by compressive load.SELECTED DRAWING: Figure 7

Description

The present disclosure relates to a battery module in which a cell is laminated.

In secondary batteries such as nickel-metal hydride batteries and lithium-ion batteries, the electrode plate inside the electrode expands and contracts due to charge / discharge and temperature changes. When the distance between the electrode plates increases, the electron conductivity of the positive electrode active material layer and the negative electrode active material layer decreases, so that the internal resistance increases and the battery performance deteriorates. For this reason, in a battery module (assembled battery) in which a plurality of cells (battery cells) are stacked so that the distance between the electrode plates does not increase, pressure (constrained load) should be applied to the cells constituting the battery module. Is desirable.

For example, in Patent Document 1, an assembled battery in which a plurality of cells are laminated is held by an arm of a manufacturing robot, inserted into a housing in a state of being preloaded so as to be compressed in the laminated direction, and the preloaded battery is released. Holds in a compressed state between the inner walls of the housing.

Japanese Unexamined Patent Publication No. 2019-145396

In this configuration, the constraining load of the assembled battery (battery module) may vary greatly depending on the accuracy of the dimensions of the housing and the cell. Further, since the constraining load is obtained by releasing the preload from the state in which the battery module is preloaded so as to be compressed in the stacking direction, it is difficult to apply a large constraining load to the battery module.

It is an object of the present disclosure to provide a battery module capable of applying a desired large restraining load.

The battery module of the present disclosure is a battery module in which a plurality of cell cells are laminated between a pair of end plates, and includes a restraining member that connects the pair of end plates and restrains the cell cells in the stacking direction. The battery module is arranged between a pair of wedge members and a pair of wedge members that are arranged between the cells and apply a restraining load in the stacking direction by applying a load in a direction orthogonal to the stacking direction. A strain member is provided, which receives a compressive load when a load is applied to the wedge member in a direction orthogonal to the stacking direction and applies a restraining load in the stacking direction by lateral strain due to the compressive load.

According to this configuration, the plurality of cells stacked between the pair of end plates are constrained by the restraining member. By applying a load to the pair of wedge members arranged between the cells in the direction orthogonal to the stacking direction, a restraining load is applied from the wedge members in the stacking direction. The strain member arranged between the pair of wedge members receives a compressive load when a load is applied to the wedge member in a direction orthogonal to the stacking direction, and a restraining load is applied in the stacking direction by the lateral strain due to the compressive load. do. Since the restraining load is applied by the pair of wedge members and the strain member, a large restraining load can be obtained. The magnitude of the restraint load can be controlled by the magnitude of the load applied to the wedge member in the direction orthogonal to the stacking direction, and a desired restraint load can be applied.

According to the present disclosure, it is an object of the present invention to provide a battery module capable of applying a desired large restraining load.

It is a perspective view of the battery module 1 which concerns on this embodiment. FIG. 1 is a cross-sectional view taken along the line AA of FIG. 1, showing a wedge member 30 and cells 10 on both sides of the wedge member 30. It is a three-sided view of a wedge 31. It is a three-sided view of a wedge receiver 32. It is a figure which shows the assembling method of the wedge member 30. It is a figure which showed the relationship of the force applied to the wedge 31 and the wedge receiver 32. It is a figure for demonstrating the restraint load, and is the same cross-sectional view as FIG. It is a figure explaining the modification, and is the figure corresponding to FIG. 5C.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals and the description thereof will not be repeated.

FIG. 1 is a perspective view of the battery module 1 according to the present embodiment. As shown in FIG. 1, the battery module 1 includes a pair of end plates 7 and 8, a restraint band 9, a plurality of cell cells 10, and a plurality of spacers 20. The plurality of cells 10 are square batteries, and a plurality of the cells 10 are arranged in a row along the stacking direction thereof. Further, the plurality of cell cells 10 are arranged so that the end faces in the thickness direction face the end faces in the thickness direction of the adjacent cell cells 10. The plurality of spacers 20 are provided in each of the plurality of cell cells 10.

The cell 10 is laminated between the pair of end plates 7 and 8, and the end plates 7 and 8 are provided with a restraint band 9 so as to suppress an increase in the distance between the end plates 7 and 8. Be done.

The restraint band 9 that functions as a restraint member surrounds the pair of end plates 7 and 8 and the plurality of cell cells 10, and the end plate 7 is connected by the restraint band 9 to connect the pair of end plates 7 and 8. , The increase in the distance between 8 is suppressed. The restraint band 9 is made of, for example, a seamless annular metal or a seamless annular carbon fiber reinforced plastic (CFRP).

The cell 10 is a sealed square secondary battery, for example, a lithium ion battery. The cell 10 includes a rectangular battery case 11 having an opening on the upper surface, a lid 13 that closes (seals) the opening, and a flat electrode body (not shown) housed in the battery case 11. ) And. The lid 13 is provided with a safety valve 13j, a positive electrode external terminal 15a, and a negative electrode external terminal 15b. The entire circumference of the lid 13 is joined to the opening of the battery case 11 by welding. As a result, the inside of the cell 10 is sealed. When the internal pressure of the cell 10 rises and the valve opening pressure is reached, the safety valve 13j opens the sealed state of the cell 10 by opening the safety valve 13j, and discharges the gas in the cell 10 to the outside of the battery.

The battery module 1 has the cell 10 connected in series, and the positive electrode external terminal 15a and the negative electrode external terminal 15b of the cell 10 adjacent to each other in the stacking direction are electrically connected by the bus bar 3. The battery module 1 may be a cell module 10 connected in parallel.

In the battery module 1, a wedge member 30 is arranged at the center of the cell 10 in the stacking direction. The wedge member 30 is arranged between the cell 10 and the cell 10. On both sides of the wedge member 30, side members 40 made of an elastic body are arranged between the cell 10 and the cell 10.

FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1, showing a wedge member 30 and cells 10 on both sides of the wedge member 30. As shown in FIG. 2, a pair of wedge members 30 are arranged between the cell 10 and the cell 10 at intervals in the vertical direction. A metal plate 50 is arranged between the wedge member 30 and the cell 10, and the restraining load by the wedge member 30 and the strain member 60 is transmitted to the cell 10 via the metal plate 50.

The wedge member 30 is composed of a wedge 31 and a pair of wedge receivers 32. FIG. 3 is a three-view view of the wedge 31. As shown in FIG. 3, the wedge 31 is provided with a pair of inclined surfaces 31b, the side surfaces thereof are formed in a substantially trapezoidal shape, and a plurality of resin injection holes 31a are provided. FIG. 4 is a three-view view of the wedge receiver 32. As shown in FIG. 4, the wedge receiver 32 includes an inclined surface 32b that abuts on the inclined surface 31b of the wedge 31, and a vertical surface 32c that abuts on the metal plate 50. Further, a plurality of adhesive grooves 32a into which the adhesive is injected are formed on the vertical surface 32c of the wedge receiver 32.

FIG. 5 is a diagram showing a method of assembling the wedge member 30. By adhering the vertical surface 32c of the wedge receiver 32 to the metal plate 50 with an adhesive having a small adhesive force, the pair of wedge receivers 32 are temporarily fixed in the vertical direction of the metal plate 50. As shown in FIG. 5A, a pair of metal plates 50 to which the wedge receiver 32 is temporarily fixed are arranged between the cell 10 and the cell 10, and the metal plate 50 and the cell 10 are brought into contact with each other. After connecting the pair of end plates 7 and 8 with the restraint band 9, a preload is applied in the direction of the end plates 7 and 8 by the jig 100 as shown in FIG. 5 (A).

Subsequently, as shown in FIG. 5B, the wedge 31 is inserted between the pair of wedge receivers 32 in the left-right direction from the vertical direction, and is held by a predetermined load. Resin is injected from the resin injection hole 31a of the upper wedge 31 in a state where the inclined surface 31b of the wedge 31 (see FIG. 3) and the inclined surface 32b of the wedge receiver 32 (see FIG. 4) are in contact with each other. As a result, the space surrounded by the upper and lower wedge members 30 and the left and right metal plates 50 is filled with resin, and the air and excess resin existing in the space are discharged from the resin injection hole 31a of the lower wedge 31. The resin to be injected may be, for example, a polyurethane resin, a polyethylene resin, or the like, and a resin having a large Poisson ratio after curing is desirable. When the injected resin is cured, the strain member 60 is formed.

When the resin is cured and the strain member 60 is formed, a load is applied to the wedge 31 from the vertical direction (the wedge 31 is driven) as shown in FIG. 5 (C). At this time, the temporary fixing of the metal plate 50 and the wedge receiver 32, which had been temporarily fixed with an adhesive having a small adhesive force, is released, and the wedge receiver 32 becomes movable relative to the metal plate 50. FIG. 6 is a diagram showing the relationship between the force applied to the wedge 31 and the wedge receiver 32. In FIG. 6, the magnitude of the restraining load applied to the metal plate 50 (cell 10) from the wedge receiver 32 is defined as F0. Assuming that the coefficient of friction between the metal plate 50 and the wedge receiver 32 is μ ₁ and the coefficient of friction between the wedge 31 and the wedge receiver 32 is μ ₂ , the friction force between the metal plate 50 and the wedge receiver 32 is μ ₁ F0. Become. When the angle between the inclined surface 31b of the wedge 31 (the inclined surface 32b of the wedge receiver 32) and the vertical direction is θ, the vertical drag applied to the inclined surface 32b of the wedge receiver 32 is F0cosθ, and the wedge 31 and the wedge due to this vertical resistance The frictional force between the receivers 32 is μ ₂ F0 cos θ. Therefore, assuming that the load applied to the wedge 31 is F3, F3 / 2 is larger than μ ₂ F0cos ² θ (because the wedge receiver 31 is a pair), and the friction coefficient μ ₁ and the friction coefficient μ ₂ are “μ ₁ <. In the relationship of "μ ₂ cos ² θ", the wedge 31 is strained by the wedge 31 and the wedge receiver 32 (wedge member 30) moving relative to the metal plate 50 while applying a restraining load to the wedge receiver 32. The member 60 is compressed. The friction coefficient μ ₁ and the friction coefficient μ ₂ are set to, for example, the surface roughness of the wedge member 30 (wedge 31 and wedge receiver 32) and the metal plate 50 so that the relationship of “μ ₁ <μ ₂ cos ² θ” is established. You may adjust.

When the strain member 60 is compressed by the wedge member 30, a lateral strain is generated in the strain member 60 due to the compressive load. Due to this lateral strain, the strain member 60 applies a restraining load to the metal plate 50 (cell 10).

When the wedge 31 is driven in and a desired restraining load is applied to the cell 10 (metal plate 50) by the wedge member 30 and the strain member 60, an adhesive is applied to the adhesive groove 32a of the wedge receiver 32 as shown in FIG. 5 (D). After pouring, the wedge receiver 32 and the metal plate 50 are fixed, and the assembly of the wedge member 30 is completed. The wedge 31 is held by the frictional force with the wedge receiver 32.

FIG. 7 is a diagram for explaining a restraint load, and is a cross-sectional view similar to FIG. 2. As shown in FIG. 7, a pair of wedge members 30 (wedge 31, wedge receiver 32) applies a restraining load F1 in the stacking direction of the cell 10, and a lateral strain of the strain member 60 imparts a restraining load F2. .. The angle of the inclined surface 31b of the wedge 31 and the size of the wedge receiver 32 so that the sizes of the restraint load F1 and the restraint load F2 applied to the cell 10 (metal plate 50) per unit area are almost the same. It is desirable that the contact area with the metal plate 50), the size (volume) of the strain member 60, and the Poisson's ratio of the strain member 60 be selected, whereby the load can be made uniform on the restraint surface. However, this requirement is not mandatory.

In the present embodiment, since the restraint load is applied to the cell 10 by the pair of wedge members 30 and the strain member 60, a large restraint load can be obtained. The magnitude of the restraint load can be controlled by the magnitude of the load (F4) applied to the wedge member 30 in the direction orthogonal to the stacking direction, and a desired restraint load can be applied.

In a restraint band having a seam (for example, the seam is welded or bonded), it is difficult to secure the strength of the seam, so that a large restraint load may not be applied. However, in the present embodiment, the restraint band 9 has a seam. Since a non-annular metal or a seamless annular carbon fiber reinforced plastic is used, a large restraining load can be applied.

In the present embodiment, the wedge member 30 and the strain member 60 are arranged in the central portion in the stacking direction of the cell 10, but the place where the wedge member 30 and the strain member 60 are arranged is not limited to the central portion. .. Further, the wedge member 30 and the strain member 60 may be provided at a plurality of places.

(Modification example)
In the above embodiment, the friction coefficient μ ₁ and the friction coefficient μ ₂ are set to have a relationship of “μ ₁ <μ ₂ cos ² θ”, and the wedge 31 is driven into the wedge holder 32 to restrain the load. The wedge 31 and the wedge receiver 32 (wedge member 30) moved relative to the metal plate 50 and compressed the strain member 60. In the modified example, even if the relationship between the friction coefficient μ ₁ and the friction coefficient μ ₂ does not hold “μ ₁ <μ ₂ cos ² θ”, the wedge 31 is constrained to the wedge receiver 32 by driving the wedge 31. The wedge 31 and the wedge receiver 32 (wedge member 30) move relative to the metal plate 50 so that the strain member 60 can be compressed.

FIG. 8 is a diagram illustrating a modified example, and is a diagram corresponding to FIG. 5 (C). In FIG. 8, 110 is a jig that applies a load to the wedge receiver 32 in the direction in which the wedge 31 is driven. At the same time as applying a load to the wedge 31 from above and below (driving the wedge 31), a load is applied to the wedge receiver 32 by the jig 110. By adjusting the magnitude of the load applied to the wedge 31 and the load applied to the wedge receiver 32, the strain member 60 is compressed by the load applied to the wedge 31 while applying a restraining load to the wedge receiver 32, and the strain member 60 is compressed into the wedge receiver 32. The strain member 60 is compressed by the applied load. With this configuration, even if the relationship between the friction coefficient μ ₁ and the friction coefficient μ ₂ does not hold “μ ₁ <μ ₂ cos ² θ”, the strain member 60 is provided by the wedge member 30 (wedge 31, wedge receiver 32). A compressive load can be applied to the metal plate 50 (cell 10) due to the lateral strain of the strain member 60.

By exemplifying the embodiments in the present disclosure, the following embodiments can be exemplified.

1) A battery module (1) in which a plurality of cell cells (10) are laminated between a pair of end plates (7, 8), and the pair of end plates (7, 8) are connected to the cell cell (10). ) Is placed between the restraining member (9) that restrains the stacking direction and the cell (10), and the load is applied in the direction orthogonal to the stacking direction to apply the restraining load in the stacking direction. It is placed between the wedge member (30) and the pair of wedge members (30), receives a compressive load when a load is applied to the wedge member (30), and is constrained in the stacking direction due to lateral strain due to the compressive load. A battery module comprising a strain member (60), which imparts.

2) In 1, the wedge member (30) is composed of a pair of wedge receivers (32) and a wedge (31) arranged between the wedge receivers (32), and is formed by the wedge (31) and the wedge receiver (32). , A compressive load is applied to the strain member (60).

3) In 2, the wedge receiver (32) is in contact with the plate (50), and a restraining load of the cell (10) is applied via the plate (50).

4) In 3, a resin injection hole (31a) is formed in the wedge (31), and the resin injected from the resin injection hole (31a) is formed in the pair of wedge members (30) and the pair of plates (50). The strain member (60) is formed by filling the space formed between them and curing the resin.

According to this configuration, since the strain member (60) fills the space formed between the pair of wedge members (30) and the pair of plates (50), the lateral force generated by the compressive load on the strain member (60). The strain can be efficiently applied to the cell (10) (plate (50)) as a restraining load.

5) In 4, the wedge member (30) (wedge (31) and wedge holder (32)) while applying a restraining load to the wedge receiver (32) by driving the wedge (31) after the resin is cured. Moves relative to the plate 50, and the strain member 60 receives a compressive load, which causes lateral strain and applies a restraining load.

6) In step 5, after applying the desired restraining load, the wedge receiver (32) and the plate (50) are adhered and fixed.

The embodiments disclosed this time should be considered to be exemplary and not restrictive in all respects. The scope of the present invention is shown by the scope of claims rather than the description of the embodiments described above, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 Battery module, 7 end plate, 8 end plate, 9 restraint band, 10 cell, 20 spacer, 30 wedge member, 31 wedge, 31a resin injection hole, 31b inclined surface, 32 wedge receiving, 32a adhesive groove, 32b inclined surface , 32c vertical plane, 40 side members, 50 metal plates, 60 strain members.

Claims (1)

A battery module in which multiple cells are stacked between a pair of end plates.
A restraining member that connects the pair of end plates and restrains the cell in the stacking direction.
A pair of wedge members arranged between the cells and applying a restraining load in the stacking direction by applying a load in a direction orthogonal to the stacking direction.
A strain member which is arranged between the pair of wedge members, receives a compressive load when the load is applied to the wedge member, and applies a restraining load in the stacking direction by lateral strain due to the compressive load. Equipped with a battery module.

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