Battery pack

Abstract

To provide a battery pack which enables secure fixture of battery cells and efficient cooling of the battery cells.SOLUTION: A battery pack 100 includes: multiple battery cells 11 laminated; a case body 21 which holds the multiple battery cells 11; an adhesion member 51 which is inserted between the battery cell 11 and the case body 21 and bonds the battery cells 11 to the case body 21; and a heat transmission member 41 which has an elastic modulus smaller than that of the adhesion member 51 and is inserted between the battery cells 11 and the case body 21.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a battery pack. [Background technology]

[0002] For example, U.S. Patent No. 11005131 (Patent Document 1) discloses a battery box comprising a housing, a plurality of cells contained in the housing, and a thermally conductive structural adhesive filled between the bottom of the housing and the plurality of cells.

[0003] Furthermore, JP 2016-15328 A (Patent Document 2) discloses an electricity storage device including a case, a power generating element disposed within the case, a cooling member disposed on the underside of the case and forming a flow passage through which a refrigerant flows, and a heat transfer member disposed between the cooling member and the case and made of a material with higher thermal conductivity than air.

[0004] In addition, JP 2014-60088 A (Patent Document 3) discloses a secondary battery device comprising an outer case having a battery accommodating chamber, a battery cell accommodated in the battery accommodating chamber, and an adhesive that adheres and fixes the battery cell to the inner surface of the outer case. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 11005131 [Patent Document 2] JP 2016-15328 A [Patent Document 3] JP 2014-60088 A Summary of the Invention [Problem to be solved by the invention]

[0006] As disclosed in the above-mentioned patent documents, there is known a battery pack including a plurality of battery cells and a holding member such as a case body for holding the plurality of battery cells. In such a battery pack, it is required to reliably fix the battery cells to the holding member while efficiently cooling the battery cells, which are heat generating bodies.

[0007] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to solve the above-mentioned problems and to provide a battery pack that is capable of both reliably fixing battery cells and efficiently cooling the battery cells. [Means for solving the problem]

[0008] A battery pack according to the present invention includes a plurality of stacked battery cells, a holding member that holds the plurality of battery cells, an adhesive member that is interposed between the battery cells and the holding member and that adheres the battery cells and the holding member, and a heat transfer member that has a smaller elastic modulus than the adhesive member and is interposed between the battery cells and the holding member.

[0009] According to the battery pack configured in this manner, the battery cells can be reliably fixed to the holding member by the adhesive member. In addition, since the heat transfer member has a smaller elastic modulus than the adhesive member and is more easily deformed than the adhesive member, the heat transfer member can be easily deformed to follow the deformation of the battery cells. This makes it possible to efficiently transfer heat generated in the battery cells to the holding member through the heat transfer member, thereby efficiently cooling the battery cells.

[0010] Also preferably, the heat transfer member has a higher thermal conductivity than the adhesive member. According to a battery pack configured in this manner, heat from the battery cells can be transferred more efficiently to the holding member through the heat transfer member.

[0011] Preferably, the battery cell includes a rectangular bottom surface having short sides extending in a stacking direction of the battery cells and long sides extending in a direction perpendicular to the stacking direction of the battery cells, the adhesive member is disposed on both ends of the bottom surface in the direction perpendicular to the stacking direction of the battery cells, and the heat transfer member is disposed in a center of the bottom surface in the direction perpendicular to the stacking direction of the battery cells.

[0012] In the battery pack configured in this manner, adhesive members that are less likely to deform are disposed at both ends of the bottom surface that are subject to a relatively small amount of deformation when the battery cells deform, and a heat transfer member that is more easily deformed is disposed at the center of the bottom surface that is subject to a relatively large amount of deformation when the battery cells deform. This makes it possible to more reliably fix the battery cells to the holding member while more efficiently cooling the battery cells.

[0013] Preferably, the battery cell has a bottom surface and a side surface rising from the bottom surface and having an area smaller than that of the bottom surface, the adhesive member is disposed on the side surface, and the heat transfer member is disposed on the bottom surface.

[0014] In the battery pack configured in this manner, the adhesive member that is less likely to deform is disposed on the side surface that is subject to a relatively small amount of deformation when the battery cell deforms, and the heat transfer member that is more easily deformed is disposed on the bottom surface that is subject to a relatively large amount of deformation when the battery cell deforms. This makes it possible to more reliably fix the battery cell to the holding member while more efficiently cooling the battery cell.

[0015] Also preferably, the contact area of ​​the heat transfer member with respect to the battery cell is larger than the contact area of ​​the adhesive member with respect to the battery cell.

[0016] According to a battery pack configured in this manner, heat from the battery cells can be transferred more efficiently to the holding member through the heat transfer member.

[0017] Preferably, the battery cells have a thin plate shape with a thickness direction aligned with a stacking direction of the battery cells. When viewed in the stacking direction of the battery cells, the heat transfer members are disposed symmetrically on both sides of a center line of the battery cells extending in the vertical direction.

[0018] A battery pack configured in this manner can cool the battery cells in a balanced manner on both sides of the center line of the battery cells.

[0019] Preferably, the plurality of battery cells form a cell stack, the holding member has an opposing surface facing the cell stack, the adhesive member is provided in a frame shape along a periphery of the opposing surface, and the heat transfer member is made of a heat transfer material having flowability and is provided in a central region of the opposing surface surrounded by the adhesive member.

[0020] According to the battery pack configured in this manner, a mechanism for fastening the heat transfer member having fluidity to the opposing surface can be easily configured. Effect of the Invention

[0021] As described above, according to the present invention, it is possible to provide a battery pack that is capable of both reliably fixing the battery cells and efficiently cooling the battery cells. [Brief description of the drawings]

[0022] [Figure 1] 1 is a cross-sectional view showing a battery pack according to an embodiment of the present invention. [Diagram 2] 2 is a perspective view showing a battery cell that constitutes the battery pack in FIG. 1. [Diagram 3] FIG. 2 is an exploded view showing the battery pack in FIG. [Figure 4] 2 is a perspective view showing a schematic diagram of an assembly process of the battery pack in FIG. 1. [Diagram 5] 1A to 1C are diagrams illustrating the deformation of a battery cell (bottom surface). [Figure 6] 1. FIG. 4 is a cross-sectional view showing a first modified example of the battery pack in FIG. [Figure 7] 11A and 11B are diagrams illustrating the deformation of a battery cell (a bottom surface and a fourth side surface). [Figure 8] 1. FIG. 4 is a perspective view showing a second modified example of the battery pack in FIG. [Figure 9]1. FIG. 4 is a perspective view showing a third modified example of the battery pack in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described with reference to the accompanying drawings, in which the same or corresponding components are designated by the same reference numerals.

[0024] Fig. 1 is a cross-sectional view showing a battery pack in an embodiment of the present invention, Fig. 2 is a perspective view showing a battery cell constituting the battery pack in Fig. 1, Fig. 3 is an exploded view showing the battery pack in Fig. 1.

[0025] 1 to 3, a battery pack 100 is used as a power source for driving a vehicle such as a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), or a battery electric vehicle (BEV).

[0026] In this specification, for the convenience of explaining the structure of the battery pack 100, the stacking direction of the multiple battery cells 11 described later and the axis extending horizontally are referred to as the "Y-axis," the direction perpendicular to the Y-axis and extending horizontally are referred to as the "X-axis," and the axis extending vertically are referred to as the "Z-axis."

[0027] The battery pack 100 has a plurality of battery cells 11 and a case body 21. The plurality of battery cells 11 are stacked in the Y-axis direction. The case body 21 holds the plurality of battery cells 11. The case body 21 holds the plurality of battery cells 11 in a space 70 described below. In this embodiment, the case body 21 corresponds to the "holding member" of the present invention.

[0028] 2, the battery cell 11 is a lithium ion battery. The battery cell 11 is square and has a rectangular thin plate shape. The multiple battery cells 11 are stacked so that the thickness direction of the battery cell 11 is the Y-axis direction.

[0029] The battery cell 11 has an exterior body 12. The exterior body 12 is made of a rectangular parallelepiped housing, and forms the external appearance of the battery cell 11. The exterior body 12 contains an electrode assembly and an electrolyte.

[0030] Exterior body 12 has a first side surface 13, a second side surface 14, a third side surface 19, a fourth side surface 20, a top surface 15, and a bottom surface 16. Each of first side surface 13 and second side surface 14 is a plane perpendicular to the Y axis. First side surface 13 and second side surface 14 face opposite each other in the Y axis direction. Each of first side surface 13 and second side surface 14 has the largest area among the multiple side surfaces that exterior body 12 has.

[0031] Each of the third side surface 19 and the fourth side surface 20 is a plane perpendicular to the X-axis. The third side surface 19 and the fourth side surface 20 face in opposite directions in the X-axis direction. Each of the third side surface 19 and the fourth side surface 20 has an area smaller than that of the bottom surface 16. Each of the third side surface 19 and the fourth side surface 20 has the smallest area among the multiple side surfaces that the exterior body 12 has.

[0032] Top surface 15 and bottom surface 16 each consist of a plane perpendicular to the Z-axis. Top surface 15 faces upward. Bottom surface 16 faces downward. Top surface 15 is provided with a gas exhaust valve 17 for exhausting gas to the outside of exterior body 12 when the internal pressure of exterior body 12 exceeds a predetermined value due to gas generated inside exterior body 12.

[0033] Each of the first side surface 13, the second side surface 14, the third side surface 19, the fourth side surface 20, the top surface 15, and the bottom surface 16 has a rectangular shape. Each of the first side surface 13 and the second side surface 14 has a rectangular shape in which the X-axis direction is the longitudinal direction and the Z-axis direction is the short side direction. Each of the third side surface 19 and the fourth side surface 20 has a rectangular shape in which the Z-axis direction is the longitudinal direction and the Y-axis direction is the short side direction. Each of the top surface 15 and the bottom surface 16 has a rectangular shape in which the X-axis direction is the longitudinal direction and the Y-axis direction is the short side direction.

[0034] The battery cell 11 further has electrode terminals 18, each of which is a pair of a positive terminal 18P and a negative terminal 18N. The electrode terminals 18 are provided on the top surface 15. The positive terminal 18P and the negative terminal 18N are provided apart from each other in the X-axis direction. The positive terminal 18P and the negative terminal 18N are provided on either side of the gas release valve 17 in the X-axis direction.

[0035] The multiple battery cells 11 are stacked such that the first side surfaces 13 face each other and the second side surfaces 14 face each other between the battery cells 11, 11 adjacent to each other in the Y-axis direction. As a result, the positive electrode terminals 18P and the negative electrode terminals 18N are arranged alternately in the Y-axis direction in which the multiple battery cells 11 are stacked.

[0036] Between the battery cells 11, 11 adjacent to each other in the Y-axis direction, the positive electrode terminals 18P and negative electrode terminals 18N aligned in the Y-axis direction are connected to each other by a bus bar (not shown). The multiple battery cells 11 are electrically connected to each other in series.

[0037] A cell stack 10 is composed of multiple battery cells 11 stacked in the Y-axis direction. The cell stack 10 has a rectangular parallelepiped shape. The length of the cell stack 10 in the Y-axis direction is greater than the length of the cell stack 10 in the Z-axis direction, and is greater than the length of the cell stack 10 in the X-axis direction.

[0038] The case body 21 is a box having a rectangular parallelepiped appearance. The length of the case body 21 in the Y-axis direction is greater than the length of the case body 21 in the Z-axis direction, and is greater than the length of the case body 21 in the X-axis direction. The case body 21 has a case bottom 22, a case side 23, and a case top 24.

[0039] The case bottom 22 is disposed at the bottom of the case body 21. The case bottom 22 is made of a plate material extending horizontally, with the thickness direction being in the Z-axis direction. The case bottom 22 is provided with a refrigerant passage 31 for circulating a refrigerant. The refrigerant passage 31 extends in the Y-axis direction. The case side 23 rises upward from the periphery of the case bottom 22. A space 70 that opens upward and accommodates the multiple battery cells 11 (cell stack 10) is defined on the case bottom 22 at a position surrounded by the case side 23. The multiple battery cells 11 are restrained by the case side 23 at both ends in the Y-axis direction. The case side 23 applies a restraining force (compressive force) in the Y-axis direction to the multiple battery cells 11.

[0040] Case top 24 is disposed opposite case bottom 22 in the Z-axis direction. Case top 24 is detachably attached to the upper end of case side 23, and forms a lid that closes the opening of space 70.

[0041] Coolant passage 31 for circulating the coolant is not limited to case bottom 22 , and may be provided in a member separate from case body 21 and connected to case bottom 22 , for example.

[0042] Fig. 4 is a perspective view that typically illustrates an assembly process of the battery pack in Fig. 1. Only case bottom 22 of case body 21 is illustrated in Fig. 4 and in Figs. 8 and 9 described below. With reference to Figs. 1 to 4, battery pack 100 further includes heat transfer member 41 and adhesive members 51 (51A, 51B).

[0043] The heat transfer member 41 is made of a material different from the adhesive member 51. The elastic modulus of the heat transfer member 41 is smaller than the elastic modulus of the adhesive member 51. The thermal conductivity of the heat transfer member 41 is larger than the thermal conductivity of the adhesive member 51. The heat transfer member 41 may be made of an adhesive material (adhesive) or a non-adhesive material.

[0044] The heat transfer member 41 may be a heat transfer sheet, a heat transfer grease, a gap filler, or a heat transfer gel. The heat transfer member 41 is made of a material such as acrylic, urethane, silicone, or modified silicone. The adhesive member 51 is made of a material such as epoxy, acrylic, urethane, silicone, or cyanoacrylate.

[0045] The adhesive member 51 is interposed between the battery cell 11 and the case body 21. The adhesive member 51 is interposed between the multiple battery cells 11 (cell stack 10) and the case body 21. The adhesive member 51 bonds the battery cells 11 and the case body 21. The multiple battery cells 11 (cell stack 10) are fixed to the case body 21 by the adhesive member 51.

[0046] The heat transfer member 41 is interposed between the battery cells 11 and the case body 21. The heat transfer member 41 is interposed between the plurality of battery cells 11 (cell stack 10) and the case body 21.

[0047] The adhesive members 51 are interposed between the bottom surfaces 16 of the battery cells 11 and the case bottom 22 of the case body 21. The heat transfer members 41 are interposed between the bottom surfaces 16 of the battery cells 11 and the case bottom 22 of the case body 21. The adhesive members 51 are disposed at both ends of the bottom surface 16 in the X-axis direction. The heat transfer member 41 is disposed in the center of the bottom surface 16 in the X-axis direction.

[0048] The heat transfer member 41 extends in a strip shape in the Y-axis direction on the case bottom 22. The adhesive members 51A and 51B each extend in a strip shape in the Y-axis direction on the case bottom 22. The heat transfer member 41 is disposed between the adhesive members 51A and 51B in the X-axis direction. When viewed in the Z-axis direction, the heat transfer member 41 is provided at a position overlapping the gas exhaust valve 17. When viewed in the Z-axis direction, the adhesive members 51A and 51B are provided at positions shifted on both sides in the X-axis direction from the gas exhaust valve 17.

[0049] The heat transfer member 41 and the adhesive member 51 are provided so as to cover the entire surface of the bottom surface 16. The contact area of ​​the heat transfer member 41 with the battery cell 11 is larger than the contact area of ​​the adhesive member 51 with the battery cell 11. The contact area of ​​the heat transfer member 41 with the battery cell 11 may be equal to or smaller than the contact area of ​​the adhesive member 51 with the battery cell 11.

[0050] In FIG. 1, in which the battery pack 100 is viewed in the Y-axis direction, a center line 110 of the battery cell 11 extending in the Z-axis direction (up-down direction) is shown. The battery cell 11 (exterior body 12) has a shape that is symmetrical with respect to the center line 110. The positive electrode terminal 18P is provided on one side in the X-axis direction with respect to the center line 110, and the negative electrode terminal 18N is disposed on the other side in the X-axis direction with respect to the center line 110. The length between the center line 110 and the positive electrode terminal 18P in the X-axis direction is equal to the length between the center line 110 and the negative electrode terminal 18N in the X-axis direction. The heat transfer member 41 is disposed symmetrically on both sides of the center line 110. The heat transfer member 41 has a shape that completely overlaps when folded in the Y-axis-Z axis plane including the center line 110. The adhesive members 51 (51A, 51B) are disposed symmetrically on both sides of the center line 110.

[0051] Fig. 5 is a diagram that illustrates the deformation of a battery cell (bottom surface). Referring to Fig. 5, the battery cell 11 (exterior body 12) deforms (expands) as it is charged and discharged. Focusing on the deformation of the bottom surface 16 at this time, the amount of deformation of the bottom surface 16 in the Z-axis direction is relatively large at the center of the bottom surface 16 in the X-axis direction and relatively small at both ends of the bottom surface 16 in the X-axis direction (Da>Db). This is because the exterior body 12, which has a rectangular parallelepiped appearance, is less likely to deform at positions along its edges, and the amount of deformation increases the further away from the edges.

[0052] 1 to 5, in the present embodiment, the battery cell 11 can be reliably fixed to the case body 21 by adhesive members 51 (51A, 51B) interposed between the battery cell 11 and the case body 21.

[0053] Furthermore, since the heat transfer member 41 has a smaller elastic modulus than the adhesive member 51, it is easier to deform than the adhesive member 51, and the heat transfer member 41 can be easily deformed to follow the deformation of the battery cell 11. This makes it possible to prevent the formation of a gap that acts as a heat insulating layer between the heat transfer member 41 and the battery cell 11 due to the deformation of the battery cell 11. As a result, it becomes possible to efficiently transfer heat generated in the battery cell 11 through the heat transfer member 41 to the case bottom 22 of the case body 21 in which the refrigerant passage 31 is provided, and the battery cell 11, which is a heat generating body, can be efficiently cooled.

[0054] In particular, in this embodiment, adhesive members 51 (51A, 51B) that are difficult to deform are arranged at both ends of the bottom surface 16 where the amount of deformation is relatively small, and the heat transfer member 41 that is easy to deform is arranged at the center of the bottom surface 16 where the amount of deformation is relatively large. With this configuration, it is possible to suppress the occurrence of gaps both between the adhesive members 51 and the battery cells 11 and between the heat transfer members 41 and the battery cells 11 due to deformation of the battery cells 11. In addition, the thermal conductivity of the heat transfer member 41 is greater than that of the adhesive members 51. Therefore, the battery cells 11 can be more reliably fixed to the case body 21, while the battery cells 11 can be more efficiently cooled.

[0055] In addition, because the contact area of ​​the heat transfer members 41 with the battery cells 11 is larger than the contact area of ​​the adhesive members 51 with the battery cells 11, it is possible to promote heat transfer from the battery cells 11 to the case body 21. In addition, because the heat transfer members 41 are disposed symmetrically across the center line 110 of the battery cells 11, it is possible to cool the battery cells 11 in a balanced manner on both sides of the center line 110.

[0056] Fig. 6 is a cross-sectional view showing a first modified example of the battery pack in Fig. 1. Fig. 6 shows a cross-section of the battery pack corresponding to Fig. 1. Fig. 7 is a diagram showing a schematic view of a state in which a battery cell (a bottom surface and a fourth side surface) is deformed.

[0057] 6 and 7, in this modification, adhesive members 51 (51A, 51B) are interposed between the third side surface 19 and the fourth side surface 20 of the battery cell 11 and the case side portion 23 of the case body 21. A heat transfer member 41 is interposed between the bottom surface 16 of the battery cell 11 and the case bottom portion 22 of the case body 21.

[0058] Heat transfer member 41 extends in a band shape in the Y-axis direction on case bottom 22. Heat transfer member 41 is disposed symmetrically on both sides of center line 110. Adhesive members 51A and 51B each extend in a band shape in the Y-axis direction on case side 23. Adhesive members 51 (51A, 51B) are disposed symmetrically on both sides of center line 110.

[0059] 7, when attention is paid to the deformation of the bottom surface 16 and the fourth side surface 20 (the third side surface 19 is similar to the fourth side surface 20) when the battery cell 11 expands, the amount of deformation of the bottom surface 16 in the Z-axis direction is greater than the amount of deformation of the fourth side surface 20 (the third side surface 19) in the X-axis direction (Dc>De). This is because the bottom surface 16 has a larger area than each of the third side surface 19 and the fourth side surface 20, and is more easily deformed.

[0060] In this modified example, adhesive members 51 (51A, 51B) that are difficult to deform are arranged on the third side surface 19 and the fourth side surface 20, which experience a relatively small amount of deformation, and heat transfer member 41 that is easy to deform is arranged on the bottom surface 16, which experiences a relatively large amount of deformation.

[0061] Fig. 8 is a perspective view showing a second modified example of the battery pack in Fig. 1. Fig. 8 corresponds to Fig. 4. Referring to Fig. 8, case body 21 (case bottom 22) has an opposing surface 22a. Opposing surface 22a defines space 70 and faces cell stack 10. Opposing surface 22a has a rectangular shape with the Y-axis direction as the longitudinal direction and the X-axis direction as the lateral direction.

[0062] In this modification, the adhesive member 51 is provided in a frame shape along the periphery of the opposing surface 22a. The adhesive member 51 is provided along the edge of the rectangular opposing surface 22a. The heat transfer member 41 is made of a heat transfer material having fluidity (heat transfer grease, heat transfer gel, etc.). The heat transfer member 41 is provided in the central region of the opposing surface 22a surrounded by the adhesive member 51.

[0063] According to this configuration, when assembling the battery pack, the adhesive member 51 is applied to the facing surface 22a, and then the heat transfer member 41 is placed inside the adhesive member 51. The cell stack 10 is placed on the adhesive member 51 and the heat transfer member 41, and the adhesive member 51 is cured. This allows the heat transfer member 41, which is made of heat transfer grease, heat transfer gel, or the like, to be attached to the facing surface 22a by using the adhesive member 51.

[0064] Fig. 9 is a perspective view showing a third modified example of the battery pack in Fig. 1. Fig. 9 corresponds to Fig. 4. Referring to Fig. 9, the battery pack in this modified example further has a bind bar 61. The bind bar 61 extends in the Y-axis direction. The bind bar 61 is provided at positions facing the third side surface 19 and the fourth side surface 20 of the battery cell 11 in the X-axis direction.

[0065] The adhesive member 51 is interposed between the third side surface 19 and fourth side surface 20 of the battery cell 11 and the bind bar 61. The bind bar 61 holds the multiple battery cells 11 together. The bind bar 61 is connected to the case side portion 23 of the case body 21. The heat transfer member 41 is interposed between the bottom surface 16 of the battery cell 11 and the case bottom portion 22 of the case body 21. In this modified example, the case body 21 and the bind bar 61 correspond to the holding member of the present invention.

[0066] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0067] 10 cell stack, 11 battery cell, 12 exterior body, 13 first side, 14 second side, 15 top surface, 16 bottom surface, 17 gas exhaust valve, 18 electrode terminal, 18N negative electrode terminal, 18P positive electrode terminal, 19 third side, 20 fourth side, 21 case body, 22 case bottom, 22a opposing surface, 23 case side, 24 case top, 31 refrigerant passage, 41 heat transfer member, 51, 51A, 51B adhesive member, 61 bind bar, 70 space, 100 battery pack, 110 center line.

Claims

1. A plurality of stacked battery cells; A holding member that holds a plurality of the battery cells; an adhesive member interposed between the battery cell and the holding member and configured to bond the battery cell and the holding member; a heat transfer member having a smaller elastic modulus than the adhesive member and interposed between the battery cell and the holding member; the battery cell includes a bottom surface having a rectangular shape with short sides extending in a stacking direction of the battery cells and long sides extending in a direction perpendicular to the stacking direction of the battery cells; the adhesive member includes a first adhesive member disposed at one end of the bottom surface in a direction perpendicular to the stacking direction of the battery cells, and a second adhesive member disposed at the other end of the bottom surface in the direction perpendicular to the stacking direction of the battery cells and separate from the first adhesive member, the heat transfer member is disposed in a central portion of the bottom surface in a direction perpendicular to the stacking direction of the battery cells, and is arranged so as to fill a space between the first adhesive member and the second adhesive member in the direction perpendicular to the stacking direction of the battery cells.

2. A plurality of stacked battery cells; A holding member that holds a plurality of the battery cells; an adhesive member interposed between the battery cell and the holding member and configured to bond the battery cell and the holding member; a heat transfer member having a smaller elastic modulus than the adhesive member and interposed between the battery cell and the holding member; The plurality of battery cells form a cell stack, the holding member has an opposing surface facing the cell stack, The adhesive member is provided in a frame shape along a periphery of the opposing surface, The heat transfer member is made of a heat transfer material having flowability and is provided in a central region of the opposing surface surrounded by the adhesive member.

3. The battery pack according to claim 1 , wherein the heat transfer member has a thermal conductivity greater than that of the adhesive member.

4. The battery pack according to claim 1 , wherein a contact area of ​​the heat transfer member with respect to the battery cell is larger than a contact area of ​​the adhesive member with respect to the battery cell.

5. The battery cells have a thin plate shape in which the stacking direction of the battery cells is a thickness direction, 5 . The battery pack according to claim 1 , wherein, when viewed in a stacking direction of the battery cells, the heat transfer members are arranged symmetrically on both sides of a center line of the battery cells extending in a vertical direction.

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