Battery pack and method for diagnosing deterioration of battery pack

Abstract

To make it easy to accommodate a stack compressed in a stacking direction in a case while suppressing the height of a battery pack.SOLUTION: A battery pack 1 includes a battery stack 5 in which battery cells 10 are stacked, a case 40 in which the battery stack 5 is housed while being compressed in a stacking direction D, and a first inclined surface 24A formed on an abutment surface that abuts against a wide surface of the battery cell 10 and is inclined obliquely upward at the center in the stacking direction of the battery stack 5, and a second inclined surface 22A formed on the abutment surface that abuts against the wide surface of the battery cell 10 and is inclined obliquely downward at the end side in the stacking direction of the battery stack 5.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a battery pack and a method for diagnosing deterioration of a battery pack. [Background technology]

[0002] It is known that in a battery pack, a laminate is housed in a case in a state where the laminate is compressed in the stacking direction (see, for example, Patent Document 1).

[0003] Patent Document 1 discloses a configuration in which a battery pack and a pair of wedge members are placed in a battery case while compressive forces are applied from both sides of the pair of wedge members so that the battery pack is deformed into a convex shape toward the bottom.

[0004] Incidentally, in a battery pack, it is preferable to make it easier to accommodate the laminate compressed in the stacking direction in a case while keeping the height of the battery pack small. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-096540 A Summary of the Invention [Problem to be solved by the invention]

[0006] In consideration of the above, an object of the present invention is to make it easier to accommodate a stack compressed in the stacking direction in a case while reducing the height of a battery pack. [Means for solving the problem]

[0007] A battery pack of a first aspect of the present invention comprises a stack of battery cells, a case in which the stack is housed while being compressed in the stacking direction, and a first inclined surface formed on an abutment surface abutting a wide surface of the battery cell and inclined diagonally upward at the center of the stack in the stacking direction, and a second inclined surface formed on the abutment surface abutting a wide surface of the battery cell and inclined diagonally downward at an end of the stack in the stacking direction.

[0008] In a battery pack of a second aspect of the present invention, in the battery pack of the first aspect of the present invention, the first inclined surface and the second inclined surface are formed on an intermediate member that is arranged alternately with the battery cells to form the stack.

[0009] A battery pack according to a third aspect of the present invention is the battery pack according to the first aspect of the present invention, wherein the second inclined surface is formed on an inner surface of the case in the stacking direction of the stack.

[0010] In a battery pack of a fourth aspect of the present invention, in any one of the battery packs of the first to third aspects of the present invention, a cooling member is provided on the bottom surface of the case, and at least the central side of the stack in the stacking direction is in contact with the cooling member.

[0011] A battery pack according to a fifth aspect of the present invention is the battery pack according to the fourth aspect of the present invention, wherein the cooling member is curved with respect to the stacking direction.

[0012] In a battery pack of a sixth aspect of the present invention, in any one of the battery packs of the first to fifth aspects of the present invention, the laminate is arranged to move away from the bottom surface of the case when the ambient temperature drops, and to contact the bottom surface of the case when the ambient temperature rises.

[0013] A seventh aspect of the present invention is a deterioration diagnosis method for a battery pack according to the fifth or sixth aspect of the present invention, which further comprises the steps of: calculating a compressive force of the stack based on a gap between the case and the stack; Effect of the Invention

[0014] In the battery pack of the first aspect of the present invention, a first inclined surface is formed on the contact surface that contacts the wide surface of the battery cell, and is inclined obliquely upward at the center side of the stacking direction of the stack. When the stack is compressed in the stacking direction, the center side of the stack in the stacking direction is deformed so as to bend downward. Therefore, the initial deformation mode when the stack is compressed in the stacking direction is controlled. As a result, the deformation mode that causes undulation is suppressed. Then, the stack compressed in the stacking direction can be easily accommodated in a case.

[0015] Furthermore, by providing a second inclined surface that is formed on the contact surface that contacts the wide surface of the battery cell and is inclined diagonally downward at the end side of the stack in the stacking direction, when the stack is compressed in the stacking direction, the end side of the stack in the stacking direction bends so as to extend horizontally. Therefore, when the stack is compressed in the stacking direction, the height of the stack in the up-down direction is reduced. As a result, the stack compressed in the stacking direction can be easily accommodated in the case while keeping the height of the battery pack low.

[0016] In the battery pack according to the second aspect of the present invention, the first inclined surface and the second inclined surface are formed on an intermediate member that is arranged alternately with the battery cells to form a stack, so that when the stack is compressed in the stacking direction, the center side of the stack in the stacking direction is deformed so as to bend downward. Therefore, the initial deformation mode when the stack is compressed in the stacking direction is controlled. As a result, the deformation mode that causes undulation is suppressed.

[0017] In the battery pack according to the third aspect of the present invention, the second inclined surface is formed on the inner surface of the case in the stacking direction of the stack, so that when the stack is compressed in the stacking direction, the center side of the stack in the stacking direction is deformed so as to bend downward. Therefore, the initial deformation mode when the stack is compressed in the stacking direction is controlled. As a result, the deformation mode that causes undulation is suppressed.

[0018] In the battery pack according to the fourth aspect of the present invention, at least the center side of the stack in the stacking direction is in contact with the cooling member, so that the stack is pressed against the cooling member and is in close contact with the cooling member. Therefore, heat is more efficiently transferred from the stack to the case. As a result, the thermal diffusivity of the battery pack can be improved.

[0019] In the battery pack according to the fifth aspect of the present invention, the cooling member is curved with respect to the stacking direction, so that the stack deformed to bend downward is in close contact with the cooling member. Therefore, heat is transferred from the stack to the case more efficiently. As a result, the thermal diffusivity of the battery pack can be further improved.

[0020] In the battery pack according to the sixth aspect of the present invention, the laminate is disposed so as to move away from the bottom surface of the case when the ambient temperature drops and to come into contact with the bottom surface of the case when the ambient temperature rises, so that when the ambient temperature drops and the compressive force of the laminate decreases, a gap is formed between the laminate and the case. This forms an air layer between the laminate and the case, and the laminate can be kept warm. On the other hand, when the ambient temperature rises and the compressive force of the laminate increases, the laminate comes into contact with the case. This allows the heat of the laminate to be released to the outside.

[0021] In the battery pack deterioration diagnosis method of the seventh aspect of the present invention, the compressive force of the stack is calculated based on the gap between the case and the stack, making it possible to diagnose the deterioration of the battery pack in a simple manner. [Brief description of the drawings]

[0022] [Figure 1] 1 is an exploded perspective view showing a battery pack according to a first embodiment. [Diagram 2] FIG. 2 is an exploded perspective view showing the laminate according to the first embodiment. [Diagram 3] 2 is a cross-sectional view showing the center and end portions in the stacking direction of the battery pack according to the first embodiment, showing the cross section AA in FIG. [Figure 4] 1 is an exploded cross-sectional view illustrating a battery pack according to a first embodiment. [Diagram 5] 1 is a cross-sectional view showing a schematic diagram of a battery pack according to a first embodiment. [Figure 6] FIG. 1 is a cross-sectional view showing a schematic diagram of a battery pack according to a first embodiment, illustrating a state at a cryogenic temperature. [Figure 7] 11A and 11B are cross-sectional views showing the center and end portions in the stacking direction of a battery pack according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] [First embodiment] Hereinafter, a battery pack according to an embodiment will be described with reference to the drawings. The battery pack according to the first embodiment will be described as an example of a lithium ion secondary battery used as an in-vehicle power source for an electric vehicle, a hybrid vehicle, or the like. In each drawing, the arrow UP indicates the upper side in the vertical direction of the battery pack, the arrow FR indicates the front side in the front-rear direction of the battery pack, the arrow LH indicates the left side in the left-right direction of the battery pack, and the arrow D indicates the stacking direction D of the battery stack. In the first embodiment, the stacking direction D of the battery stack coincides with the front-rear direction of the battery pack.

[0024] [Battery pack 1 configuration] As shown in FIG. 1, the battery pack 1 includes a battery stack 5 as a laminate, a cooling member 30, and a case 40 that houses the battery stack 5 and the cooling member 30.

[0025] (Battery stack 5) 1 and 2, the battery stack 5 includes a plurality of battery cells (single cells) 10, a plurality of intermediate members 20 arranged in contact with wide surfaces of the battery cells 10, and bus bars 15 that electrically connect the battery cells 10. In the battery stack 5, the battery cells 10 and the intermediate members 20 are arranged alternately in the stacking direction D.

[0026] <Battery cell 10> 2, the battery cell 10 is formed into a rectangular plate shape with the plate thickness direction being the front-rear direction. The battery cell 10 has two electrode terminals 12 on its top surface 10A. One of the two electrode terminals 12 is a positive terminal and the other is a negative terminal.

[0027] <Intermediate member 20> The intermediate member 20 is made of, for example, insulating resin. This suppresses heat transfer between the battery cells 10 and insulates the battery cells 10 from each other. The intermediate member 20 may be formed with comb-like ribs for forming air passages between the intermediate member 20 and the battery cells 10.

[0028] The intermediate member 20 includes a spacer 24 and an end plate 22 .

[0029] The spacers 24 are disposed between the battery cells 10 in the stacking direction D. The spacers 24 are formed in the shape of a rectangular plate with the plate thickness direction extending in the front-rear direction.

[0030] The end plates 22 are disposed at both ends of the battery stack 5 in the stacking direction D. The end plates are formed in a rectangular plate shape with the plate thickness direction extending in the front-rear direction.

[0031] <Busbar 15> 2, the busbar 15 is formed, for example, in a rectangular plate shape with its plate thickness direction extending in the up-down direction in the stacking direction D. The busbar 15 electrically connects the electrode terminals 12 of adjacent battery cells 10.

[0032] (Case 40) 1, the case 40 is formed by, for example, die-cast aluminum. The case 40 is formed by a bottom plate 42 and a side wall 44 in the shape of a rectangular box with an open top.

[0033] The bottom plate 42 is formed in a rectangular plate shape with its thickness direction extending approximately in the vertical direction. As shown in Fig. 4, the upper surface of the bottom plate 42 (the bottom surface of the case 40) is curved to fit along the lower surface of the battery stack 5 that has been compressed and bent in the stacking direction D. The center of the bottom plate 42 in the stacking direction D is curved to protrude downward, and the ends of the bottom plate 42 in the stacking direction D are curved to extend in the stacking direction D.

[0034] 1, the side wall 44 is formed to rise upward from the periphery of the bottom plate. The side wall 44 includes a first side wall 45 formed in a rectangular plate shape with the plate thickness direction being the front-rear direction, and a second side wall 46 formed in a rectangular plate shape with the plate thickness direction being the left-right direction.

[0035] The battery stack 5 is housed in the case 40 in a state compressed in the stacking direction D. The battery stack 5 is housed in the case 40 in a state compressed in the stacking direction D by the first side wall 45.

[0036] (cooling member 30) 1 and 3, the cooling member 30 is formed in a rectangular sheet shape with its thickness direction extending substantially in the vertical direction. The cooling member 30 is formed to be substantially the same size as the lower surface of the battery stack 5.

[0037] The cooling member 30 may be a resin sheet having thermal conductivity. The cooling member 30 may be a resin sheet formed by incorporating a highly thermally conductive filler into a flexible resin sheet mainly made of acrylic or silicone resin, for example.

[0038] The cooling member 30 is attached to the upper surface of the bottom plate 42 of the case 40 by, for example, an adhesive.

[0039] 4, the cooling member 30 attached to the bottom plate 42 is curved to fit the lower surface of the battery stack 5 that has been compressed and bent in the stacking direction D. The center of the cooling member 30 in the stacking direction D is curved to protrude downward, and the end of the cooling member 30 in the stacking direction D is curved to extend in the stacking direction D.

[0040] The cooling member 30 may be provided on the upper surface of the bottom plate 42 of the case 40 corresponding to the center of the battery stack 5 in the stacking direction D.

[0041] [Detailed configuration of intermediate member 20] 3, the spacer 24 disposed in the center of the stacking direction D of the battery stack 5 is formed into a trapezoidal cross section with a width of the upper surface narrower than the width of the lower surface. The spacer 24 disposed in the center of the stacking direction D of the battery stack 5 has a contact surface that contacts the wide surface of the battery cell 10, which is a first inclined surface 24A that is inclined obliquely upward. The first inclined surface 24A is formed on both sides in the stacking direction D.

[0042] The end plates 22 arranged at both ends of the battery stack 5 in the stacking direction D are formed into a trapezoidal cross section with an upper surface that is wider than the lower surface. The end plates 22 arranged at both ends of the battery stack 5 in the stacking direction D have a contact surface that abuts against the wide surface of the battery cell 10 and a contact surface that abuts against the first side wall 45 of the case 40, which form second inclined surfaces 22A that are inclined obliquely downward.

[0043] [How to assemble battery pack 1] 4, a jig or the like is used to compress the battery stack 5 in the stacking direction D. Then, due to the first inclined surface 24A of the spacer 24 and the second inclined surface 22A of the end plate 22, the center of the battery stack 5 in the stacking direction D is bent so as to protrude downward, and the end portion in the stacking direction D is bent so as to extend in the stacking direction D.

[0044] The central axis C1 of the battery stack 5 before compression extends in the stacking direction D. The central axis C2 of the battery stack 5 after compression is bent so as to protrude downward at the center of the stacking direction D, and is bent so as to extend in the stacking direction D at the end of the stacking direction D.

[0045] Next, the battery stack 5 in a bent state, compressed in the stacking direction D, is housed in a case 40 in which a cooling member 30 is provided.

[0046] As shown in FIG. 5, the battery stack 5 is accommodated in the case 40 with the entire lower surface of the battery stack 5, which has been compressed and bent in the stacking direction D, in contact with the cooling member 30.

[0047] [Deformation of battery stack 5 due to ambient temperature] The length of the battery stack 5 in the stacking direction D changes due to, for example, linear expansion of the intermediate member 20. By utilizing this property, the battery pack 1 of the first embodiment is formed so that the lower surface of the battery stack 5 comes into contact with the cooling member 30 when the ambient temperature rises, and the lower surface of the battery stack moves away from the cooling member 30 when the ambient temperature drops.

[0048] 5, when the ambient temperature is, for example, room temperature, a compressive force acts on the battery stack 5 in the stacking direction D, and the battery stack 5 is bent so as to protrude downward at the center of the stacking direction D. Then, the entire lower surface of the battery stack 5 comes into contact with the cooling member 30.

[0049] 6, when the ambient temperature is, for example, extremely low, the compressive force in the stacking direction D of the battery stack 5 is released, and the central part of the battery stack 5 in the stacking direction D moves upward. Then, the central part of the lower surface of the battery stack 5 in the stacking direction D moves away from the cooling member 30. At this time, a gap S1 is formed between the central part of the lower surface of the battery stack 5 in the stacking direction D and the cooling member 30.

[0050] [Battery pack 1 deterioration diagnosis method] However, if a compressive force continues to act on the battery stack 5 in the stacking direction D, creep deformation occurs in the battery stack 5. It can be estimated that the greater the creep deformation of the battery stack 5, the more advanced the deterioration of the battery pack 1 is. Also, the greater the creep deformation, the lower the compressive force on the battery stack 5 in the stacking direction D.

[0051] When the compressive force in the stacking direction D on the battery stack 5 decreases, the gap S1 between the center of the lower surface of the battery stack 5 in the stacking direction D and the cooling member 30, or the gap S2 between the center of the lower surface of the battery stack 5 in the stacking direction D and the bottom plate 42 of the case 40, widens.

[0052] Therefore, the compressive force of the battery stack 5 is calculated based on the ambient temperature measured by the temperature measuring device and the gap S1 or S2 measured by a strain gauge serving as a gap detection device. Then, the deterioration of the battery pack 1 is diagnosed based on the compressive force of the battery stack 5.

[0053] [Effect] However, when the battery stack 5 is compressed in the stacking direction D, undulations with multiple belly sections may occur in the battery stack 5. In this case, the shape of the battery stack 5 becomes unstable, making it difficult to accommodate the battery stack 5 in the case 40.

[0054] The battery pack 1 of the first embodiment comprises a battery stack 5 in which battery cells 10 are stacked, a case 40 in which the battery stack 5 is housed while being compressed in a stacking direction D, and a first inclined surface 24A formed on the abutment surface that abuts against the wide surface of the battery cell 10 and inclined obliquely upward at the center of the stacking direction of the battery stack 5, and a second inclined surface 22A formed on the abutment surface that abuts against the wide surface of the battery cell 10 and inclined obliquely downward at the end side of the stacking direction of the battery stack 5 (see FIG. 3).

[0055] The first inclined surface 24A is formed on the contact surface that contacts the wide surface of the battery cell 10 and is inclined obliquely upward at the center side of the stacking direction of the battery stack 5. When the battery stack 5 is compressed in the stacking direction D, the center side of the battery stack 5 is deformed so as to bend downward. This controls the initial deformation mode when the battery stack 5 is compressed in the stacking direction D. As a result, the deformation mode that causes undulation is suppressed. This makes it easier to accommodate the battery stack 5 compressed in the stacking direction D in the case 40.

[0056] Furthermore, by providing a second inclined surface 22A that is formed on the contact surface that contacts the wide surface of the battery cell 10 and is inclined obliquely downward at the end side of the stacking direction of the battery stack 5, when the battery stack 5 is compressed in the stacking direction D, the end side of the stacking direction of the battery stack 5 is bent so as to extend in the horizontal direction. Therefore, when the battery stack 5 is compressed in the stacking direction D, the vertical height of the battery stack 5 is reduced. As a result, the battery stack 5 compressed in the stacking direction D can be easily accommodated in the case 40 while keeping the height of the battery pack down.

[0057] In the battery pack 1 of the first embodiment, the first inclined surfaces 24A and the second inclined surfaces 22A are formed on an intermediate member 20 that is arranged alternately with the battery cells 10 to form the battery stack 5 (see FIG. 3).

[0058] The first inclined surface and the second inclined surface are formed on the intermediate members 20 that are arranged alternately with the battery cells 10 to form the battery stack 5, so that when the battery stack 5 is compressed in the stacking direction D, the center side of the battery stack 5 in the stacking direction is deformed so as to bend downward. This controls the initial deformation mode when the battery stack 5 is compressed in the stacking direction D. As a result, the deformation mode that causes undulation is suppressed.

[0059] Furthermore, when the battery stack 5 is compressed in the stacking direction D, the stacking direction end sides of the battery stack 5 are bent so as to extend in the horizontal direction. Therefore, the vertical height of the battery stack 5 is reduced when the battery stack 5 is compressed in the stacking direction D. As a result, the battery stack 5 compressed in the stacking direction D can be easily accommodated in the case 40 while reducing the height of the battery pack.

[0060] In the battery pack 1 of the first embodiment, a cooling member 30 is provided on a bottom plate 42 of a case 40, and at least the center side of the battery stack 5 in the stacking direction is in contact with the cooling member 30 (see FIG. 5).

[0061] At least the center side of the battery stack 5 in the stacking direction is in contact with the cooling member 30, so that the battery stack 5 is pressed against the cooling member 30 and is in close contact with the cooling member 30. Therefore, heat is efficiently transferred from the battery stack 5 to the case 40. As a result, the thermal diffusivity of the battery pack can be improved.

[0062] In the battery pack 1 of the first embodiment, the cooling member 30 is curved with respect to the stacking direction D (see FIG. 5).

[0063] The cooling member 30 is curved with respect to the stacking direction D, so that the battery stack 5, which is deformed so as to bend downward, comes into close contact with the cooling member 30. This allows heat to be transferred more efficiently from the battery stack 5 to the case 40. As a result, the thermal diffusivity of the battery pack can be further improved.

[0064] In the battery pack 1 of the first embodiment, the battery stack 5 is configured to move away from the bottom plate 42 of the case 40 when the ambient temperature drops, and to come into contact with the bottom plate 42 of the case 40 when the ambient temperature rises (see Figures 5 and 6).

[0065] The battery stack 5 is disposed so that it moves away from the bottom plate 42 of the case 40 when the ambient temperature drops and comes into contact with the bottom plate 42 of the case 40 when the ambient temperature rises. As a result, when the ambient temperature drops and the compressive force of the battery stack 5 decreases, a gap 2 is formed between the battery stack 5 and the case 40. This forms an air layer between the battery stack 5 and the case 40, making it possible to keep the battery stack 5 warm. On the other hand, when the ambient temperature rises and the compressive force of the battery stack 5 increases, the battery stack 5 comes into contact with the case 40. This allows the heat of the battery stack 5 to be released to the outside.

[0066] In the diagnostic method for the battery pack 1 of the first embodiment, the compressive force of the battery stack 5 is calculated based on the gap S2 between the case 40 and the battery stack 5.

[0067] By calculating the compressive force of the battery stack 5 based on the gap S2 between the case 40 and the battery stack 5, deterioration of the battery pack can be diagnosed in a simple manner.

[0068] Second Embodiment The battery pack of the second embodiment differs from the battery pack of the first embodiment in that the configuration of the second inclined portion is different. Note that the same or equivalent parts as those described in the first embodiment will be described using the same terms or symbols.

[0069] [composition] 7, the second inclined surface 145A is formed on an inner surface of the first side wall 145 in the stacking direction D. The first side wall 145 is formed to be detachable from the case 40.

[0070] [Effect] In the battery pack 1 of the second embodiment, the second inclined surface 145A is formed on the inner surface of the case 40 in the stacking direction D of the battery stack 5 (see FIG. 7).

[0071] The second inclined surface 145A is formed on the inner surface of the case 40 in the stacking direction D of the battery stack 5, so that when the battery stack 5 is compressed in the stacking direction D, the center side of the battery stack 5 in the stacking direction is deformed so as to bend downward. This controls the initial deformation mode when the battery stack 5 is compressed in the stacking direction D. As a result, the deformation mode that causes undulation is suppressed.

[0072] Other configurations and functions and effects are substantially the same as those of the first embodiment, and therefore description thereof will be omitted.

[0073] The battery pack of the present invention has been described above based on the first and second embodiments. However, the specific configuration is not limited to these embodiments, and design changes and the like are permitted as long as they do not deviate from the gist of the invention according to each claim in the scope of the claims.

[0074] In the first embodiment, an example has been shown in which the first inclined surface 24A is formed on the spacer 24 disposed in the center of the battery stack 5 in the stacking direction D, and the second inclined surfaces 22A are formed on the end plates 22 disposed at both ends of the battery stack 5 in the stacking direction D. However, the first inclined surface 24A and the second inclined surface 22A may be formed on a plurality of intermediate members 20.

[0075] In the first and second embodiments, an example has been shown in which one battery stack 5 is housed in the case 40. However, the case may house two battery stacks 5 with an intermediate plate therebetween.

[0076] In the first and second embodiments, the bottom plate 42 is curved to fit the lower surface of the battery stack 5 that is compressed and bent in the stacking direction D. However, the bottom plate 42 may be formed flat.

[0077] In the first embodiment, an example has been described in which the first inclined surface 24A and the second inclined surface 22A are formed on both sides of the intermediate member 20 in the stacking direction D. However, the first inclined surface 24A and the second inclined surface 22A may be formed on one side of the intermediate member 20 in the stacking direction D.

[0078] In the first and second embodiments, an example has been shown in which the cooling member 30 is provided on the bottom plate 42 of the case 40. However, the battery pack 1 does not necessarily have to include the cooling member 30.

[0079] In the first and second embodiments, an example has been shown in which the cooling member 30 is provided on the entire surface of the bottom plate 42 of the case 40. However, it is sufficient that the cooling member 30 is provided at least in the center of the bottom plate 42 of the case 40 in the stacking direction D.

[0080] In the first and second embodiments, the battery pack is a lithium ion secondary battery pack. However, the battery pack may be a battery pack in which a battery stack is compressed in a stacking direction D and accommodated in a case. [Explanation of symbols]

[0081] 1 Battery pack 5 Battery stack (an example of a laminate) 10 Battery Cells 20 Intermediate parts 22A 2nd slope 24A 1st slope 30 Cooling material 40 cases 42 Bottom plate 145A 2nd slope D Stacking direction S2 Gap

Claims

1. a stack of battery cells; and a case in which the laminate is accommodated while being compressed in a stacking direction; a first inclined surface that is formed on a contact surface that contacts the wide surface of the battery cell and is inclined obliquely upward at a center side in a stacking direction of the stack; a second inclined surface that is formed on a contact surface that contacts the wide surface of the battery cell and is inclined obliquely downward at an end side in the stacking direction of the stack; A battery pack comprising:

2. The first inclined surface and the second inclined surface are formed on an intermediate member that is arranged alternately with the battery cells to form the stack. The battery pack according to claim 1 .

3. The second inclined surface is formed on an inner surface of the case in the stacking direction of the stack. The battery pack according to claim 1 .

4. A cooling member is installed on the bottom surface of the case, At least a center side of the stack in the stacking direction is in contact with the cooling member. The battery pack according to claim 1 .

5. The cooling member is curved with respect to the stacking direction. The battery pack according to claim 4.

6. The laminate comprises: When the ambient temperature drops, the bottom surface of the case is separated from the bottom surface of the case. When the ambient temperature rises, the bottom surface of the case is contacted with the The battery pack according to claim 1 .

7. The method for diagnosing deterioration of a battery pack according to claim 5 or 6, further comprising the steps of: Calculating the compressive force of the stack based on the gap between the case and the stack A method for diagnosing deterioration of a battery pack.

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