Battery module

Abstract

A battery module (1) is provided with a stack 20 configured by stacking, along the Y direction, battery cells (30a to 30e) and compression pads (40a to 40f) capable of following expansion and contraction of the battery cells. The battery cell includes an electrode region (31) where an electrode portion (34) is disposed, and a joining region (32) where a joining portion (37) in which current collecting foils (35, 36) and a tab (33) are joined is disposed. The battery module further includes cooling parts (50a to 50j) disposed so as to overlap the joining portions when viewed from the Y direction, and capable of cooling the joining portions. The compression pad has heat storage property and is arranged so as to overlap the joining portion and the cooling part when viewed from the Y direction.

Description

Battery module

[0001] The present invention relates to a battery module.

[0002] BACKGROUND ART A battery module is known that includes a cell stack in which a plurality of cells are stacked, and a compression pad that is disposed on the outer surface of the cell stack (Patent Document 1).

[0003] Special Publication No. 2023-554629

[0004] In recent years, as cells have become more powerful, the joint between the current collector foil and the tab generates heat due to the large current. However, the above-mentioned conventional technology has the problem that the joint cannot be sufficiently cooled, resulting in high temperatures near the joint.

[0005] The problem to be solved by the present invention is to provide a battery module capable of sufficiently cooling joints.

[0006] The present invention solves the above problem by arranging a cooling section so as to overlap with a joint when viewed from the first direction, and arranging an absorption layer having heat storage properties so as to overlap with the joint and the cooling section when viewed from the first direction, in a battery module having a stack in which battery cells and absorption layers are stacked in a first direction.

[0007] According to the present invention, the joint can be cooled sufficiently.

[0008] Fig. 1 is a plan view showing a battery module in an embodiment of the present invention. Fig. 2 is an enlarged cross-sectional view of part II in Fig. 1. Fig. 3 is a plan view showing a battery cell in an embodiment of the present invention. Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 1.

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] Fig. 1 is a plan view showing a battery module 1 according to this embodiment. Fig. 2 is an enlarged cross-sectional view of part II in Fig. 1. Fig. 3 is a plan view showing battery cells 30a to 30e according to this embodiment. Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 1.

[0011] The battery module 1 is, but is not limited to, an in-vehicle battery module. For example, the battery module 1 is mounted under the floor of a cabin of a vehicle. However, the battery module 1 may also be used for purposes other than in-vehicle use.

[0012] The battery module 1 in this embodiment includes a module case 10 and a stacked body 20. The module case 10 houses the stacked body 20. The module case 10 is made of, for example, a metal material. The module case 10 in this embodiment includes a bottom plate 11, a pair of end plates 12, a pair of side plates 13, and a top plate 14 (see FIG. 4 ).

[0013] As shown in Fig. 4, the bottom plate 11 is a plate member that forms the bottom of the module case 10 and supports the stack 20. End plates 12 are provided upright on this bottom plate 11. As shown in Fig. 1, the pair of end plates 12 are plate members that form the sides of the module case 10 and are arranged to sandwich the stack 20. The end plates 12 in this embodiment press the stack 20 in the Y direction in the figure.

[0014] A pair of side plates 13 are also erected on the bottom plate 11. The pair of side plates 13 are plate members that form the sides of the module case 10. The side plates 13 are spaced apart from the stack 20. In this embodiment, the side plates 13 face the tabs 33. The pair of side plates 13 are connected to the pair of end plates 12, thereby forming a frame shape together with the pair of end plates 12.

[0015] 4, the top plate 14 is a plate member that forms a lid portion of the module case 10. The top plate 14 covers the stacked body 20 from above.

[0016] 1, the stack 20 is housed in a module case 10 and is sandwiched and compressed between end plates 12. The stack 20 includes a plurality of battery cells 30a-30e, a plurality of compression pads 40a-40f, and a plurality of cooling sections 50a-50j. The compression pads 40a-40f in this embodiment are an example of the "absorbent layer" in the present invention.

[0017] The battery cells 30a-30e and the compression pads 40a-40f are stacked alternately along the Y direction (stacking direction) in the figure. The cooling units 50a-50j are stacked so as to be sandwiched between the battery cells 30a-30e and the compression pads 40a-40f. The Y direction in this embodiment corresponds to an example of the "first direction" in the present invention.

[0018] As shown in Fig. 3, the battery cells 30a to 30e are flat-plate battery cells. The battery cells 30a to 30e each include an electrode region 31, a bonding region 32, and a tab 33. The electrode region 31 is an area where an electrode portion 34 is disposed. The electrode portion 34 includes a positive electrode (not shown), a positive electrode current collector foil 35, a negative electrode (not shown), a negative electrode current collector foil 36, and an electrolyte (not shown). The electrode portion 34 may include a solid electrolyte as the electrolyte.

[0019] The bonding region 32 is a region where a bonding portion 37 is disposed, where the positive electrode current collector foil 35 or the negative electrode current collector foil 36 is overlapped and bonded to the tab 33. The bonding region 32 in this embodiment is provided at the end of the side surface of the electrode region 31 in the Y direction.

[0020] A tab 33 extends from this joining region 32. As shown in Fig. 1 , the tab 33 is disposed so as to face the tab 33 of an adjacent battery cell, and is joined to the tab 33 of the adjacent battery cell. Note that in this embodiment, the tabs 33 are joined directly to each other, but this is not limiting, and the tabs 33 may also be electrically connected to each other via a bus bar or the like.

[0021] 3, in this embodiment, the bonding regions 32 are provided on both the −X and +X sides of the battery cell in the drawing, but this is not limited thereto, and the bonding regions 32 may be provided on only one side of the battery cell. In this case, the two tabs 33 are joined to the positive and negative electrode current collector foils 35 and 36, respectively, at the bonding regions 32 and extend in one direction from the bonding regions 32.

[0022] 1, the compression pads 40a to 40f are sheet-like members that contact the battery cells 30a to 30e. In this embodiment, the compression pads 40a to 40f are arranged so as to overlap the bonding portion 37 (see FIG. 3) of the bonding region 32 and the cooling portions 50a to 50j when viewed from the Y direction.

[0023] The compression pads 40a-40f are elastic and can accommodate the expansion and contraction of the battery cells 30a-30e. In particular, if the electrolyte layer contains a solid electrolyte, the battery cells 30a-30e will expand and contract significantly. However, the compression pads 40a-40f in this embodiment can accommodate the expansion and contraction of the battery cells 30a-30e that contain a solid electrolyte. Furthermore, the compression pads 40a-40f contract slightly due to the pressure applied by the end plates 12, and use their elastic force to press against the battery cells 30a-30e.

[0024] The compression pads 40a-40f also have heat storage properties and can exchange heat between the battery cells 30a-30e and the cooling units 50a-50j. Specifically, the compression pads 40a-40f can receive heat from the electrode regions 31 of the battery cells 30a-30e and transfer the transferred heat to the cooling units 50a-50j or the end plates 12.

[0025] Examples of materials that can be used to make these compression pads 40a-40f include Alpha Gel with dispersed beads, foamed resin with dispersed beads, and elastomer with dispersed beads. Examples of beads include capsules made of plastic or the like that contain a heat transfer material or heat storage material. Examples of heat transfer materials include alumina, and examples of heat storage materials include normal paraffin.

[0026] The compression pad 40a is interposed between the battery cell 30a and the end plate 12. The compression pad 40a presses the joining area 32 of the battery cell 30a towards the cooling portions 50a, 50b.

[0027] Furthermore, the compression pad 40b is interposed between the battery cell 30a and the battery cell 30b. This compression pad 40b is in contact with the cooling portions 50a to 50d, and presses the cooling portions 50a and 50b toward the joining region 32 of the battery cell 30a, and presses the cooling portions 50c and 50d toward the joining region 32 of the battery cell 30b.

[0028] The compression pad 40c is interposed between the battery cells 30b and 30c. The compression pad 40c presses the joining area 32 of the battery cell 30b toward the cooling sections 50c and 50d, and presses the joining area 32 of the battery cell 30c toward the cooling sections 50e and 50f.

[0029] The compression pad 40d is interposed between the battery cells 30c and 30d. This compression pad 40d is in contact with the cooling portions 50e to 50h, and presses the cooling portions 50e and 50f toward the joining region 32 of the battery cell 30c, and presses the cooling portions 50g and 50h toward the joining region 32 of the battery cell 30d.

[0030] The compression pad 40e is interposed between the battery cells 30d and 30e. The compression pad 40e presses the bonding area 32 of the battery cell 30d toward the cooling sections 50g and 50h, and presses the bonding area 32 of the battery cell 30e toward the cooling sections 50i and 50j.

[0031] The compression pad 40f is interposed between the battery cell 30e and the end plate 12. The compression pad 40f presses the cooling portions 50i, 50j toward the joining region 32 of the battery cell 30e.

[0032] The cooling units 50a to 50j are interposed between the compression pads 40a to 40f and the bonding regions 32 of the battery cells 30a to 30e. When viewed from the Y direction, the cooling units 50a to 50j are arranged to overlap the bonding regions 37 (see FIG. 3) of the bonding regions 32, and cool the bonding regions 37.

[0033] The cooling units 50a to 50j are, but are not limited to, heat pipes. The structure of the cooling unit 50i is shown as an example of the structure of this heat pipe. As shown in FIG. 2, the cooling unit 50i in this embodiment includes a case 51 and a wick 52. The case 51 is, but is not limited to, a flat metal member. The internal space of the case 51 is a closed space. The wick 52 is formed on the inner wall of the case 51. The wick 52 has a capillary structure, and can move the working fluid 53 contained inside the heat pipe by capillary action.

[0034] In this heat pipe, the working fluid 53 evaporates in the portion sandwiched between the bonded region 32 and the compression pad 40f due to heat transferred from the bonded region 32 and the compression pad 40f. The vapor generated by this evaporation then moves to the portion not sandwiched between the bonded region 32 and the compression pad 40f, where it is cooled and condenses. The working fluid generated by condensation then returns to the portion sandwiched between the bonded region 32 and the compression pad 40f via the wick 52 due to capillary action. By repeating this phase change of the working fluid, heat can be transferred from the bonded region 32 and the compression pad 40f to the heat pipe. In other words, the heat pipe can cool the bonded region 32.

[0035] In this embodiment, the cooling section 50i has a rectangular cross-sectional shape. As a result, the cooling section 50i is in contact with the side surface 31a of the electrode region 31 and the joint portion 37 (see FIG. 3 ). This allows the cooling section 50i to be in close contact with the electrode region 31 and the joint portion 37, thereby improving cooling performance. Furthermore, such a cooling section 50i facilitates assembly of the stack 20, improving productivity.

[0036] The thickness T of the cooling portion 50i in the Y direction １ is the width W of the side surface 31a of the electrode region 31 １ This allows the cooling portion 50i to be in close contact with the electrode region 31 and the joint portion 37, thereby improving the cooling performance. １ is the width of the electrode region 31 in a compressed state under pressure.

[0037] As shown in FIG. 4, the cooling section 50i extends in the Z direction in the figure. The cooling section 50i includes a contact section 54 that comes into contact with the bottom plate 11. The contact section 54 is cooled by the bottom plate 11, and the vapor inside the contact section 54 can be efficiently returned to the working liquid. The contact section 54 increases the number of heat diffusion paths, thereby improving cooling performance. This improves the input / output characteristics of the battery cells 30a to 30e.

[0038] Furthermore, by using a heat pipe as the cooling unit 50i, the risk of leakage of the cooling fluid can be reduced and the cooling structure can be simplified. For example, when using a piping structure that supplies the cooling fluid from outside the battery module 1, joints or the like are required, which can lead to leakage of the fluid from the connection portions of the joints. On the other hand, when a heat pipe is used as the cooling unit 50i in this embodiment, joints or the like are basically not required, which can reduce the possibility of fluid leakage. However, the piping structure as described above may also be used for the cooling units 50a to 50j.

[0039] The cooling sections 50a to 50h and 50j basically have the same structure as the cooling section 50i. However, as shown in FIG. ２ is the width W of the cooling portion 50i ３ (See Figure 2).

[0040] That is, in this embodiment, the cooling sections 50c to 50h arranged closer to the center of the stack 20 than the cooling section 50i in the Y direction have a width W ３ Wider width W ２ Accordingly, the compression pads 40b to 40c extend to the edges of the cooling portions 50c to 50h. The cooling portions 50a, 50b, 50i, and 50j in this embodiment correspond to an example of a "first cooling portion" in the present invention, and the cooling portions 50c to 50h in this embodiment correspond to an example of a "second cooling portion" in the present invention.

[0041] The central region of the stack 20 is prone to high temperatures, so the width W of the cooling sections 50c to 50h ２ By increasing the distance between the battery cells located in the center of the stack 20 and the cooling sections 50c to 50h, the amount of heat transferred from the battery cells located in the center of the stack 20 to the cooling sections 50c to 50h can be increased, thereby dispersing the heat bias. This makes it possible to suppress temperature variations in the stack 20.

[0042] According to the battery module 1 of this embodiment, the cooling units 50a-50j can cool the joints 37 of the joint area 32 and the positive and negative current collector foils 35, 36. Furthermore, the compression pads 40a-40f press the cooling units 50a-50j to bring the joint area 32 into close contact with the cooling units 50a-50j, improving the cooling efficiency of the joints 37. Furthermore, the compression pads 40a-40f have heat storage properties. Therefore, the compression pads 40a-40f can increase the diffusion paths for heat generated at the joints 37 of the joint area 32, improving the cooling efficiency of the joints 37. As a result, the input / output characteristics of the battery cells 30a-30e can be improved.

[0043] DESCRIPTION OF SYMBOLS 1... Battery module 10... Module case 20... Laminated body 30a to 30e... Battery cells 31... Electrode area 32... Bonding area 33... Tab 40a to 40f... Compression pad 50a to 50j... Cooling section

Claims

1. A battery module comprising a laminate formed by alternately stacking battery cells and absorption layers capable of following the expansion and contraction of the battery cells multiple times along a first direction, wherein the battery cells include: electrode regions in which electrode portions are arranged; and junction regions in which junction portions are arranged where a current collecting foil and a tab are joined; the battery module further comprises a cooling portion that is arranged to overlap with the junction portions when viewed from the first direction and cools the junction portions, and that is in contact with the electrode regions and cools the electrode regions; and the absorption layer has heat storage properties, and is arranged to overlap with the junction portions and the cooling portion when viewed from the first direction.

2. A battery module according to claim 1, wherein the cooling section includes a heat pipe.

3. A battery module according to claim 1 or 2, wherein the cross-sectional shape of the cooling section is rectangular, and the cooling section is in contact with the side surface of the electrode region and the joint section.

4. A battery module according to claim 3, wherein the thickness of said cooling section in said first direction is the same as the width of said side surface in said first direction.

5. A battery module according to any one of claims 1 to 4, further comprising a module case that houses the stack, and the cooling section is in contact with the module case.

6. A battery module according to any one of claims 1 to 5, comprising a plurality of cooling sections, the plurality of cooling sections including: a first cooling section; and a second cooling section that is arranged closer to the center of the stack than the first cooling section in the first direction and has a width greater than that of the first cooling section, and the absorption layer in contact with the second cooling section extends to the edge of the second cooling section.

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