Battery pack and method for manufacturing battery pack

Abstract

To provide a battery pack in which the adhesion area of at least one of double-sided adhesive sheets located on the inner side in the thickness direction of a battery cell can be made smaller than the adhesion area of a double-sided adhesive sheet located on the outermost side.SOLUTION: The battery pack includes a double-sided adhesive sheet that is provided between two battery cells adjacent to each other in a thickness direction of the battery cells and bonds the two battery cells to each other, and the double-sided adhesive sheet has an adhesive area capable of obtaining a holding force larger than a product of a total mass of the battery cells located inside the double-sided adhesive sheet in the thickness direction of the battery cells and a predetermined impact acceleration. In addition, in the double-sided adhesive sheets adjacent to each other in the thickness direction of the battery cell, the adhesive area of the double-sided adhesive sheet located inside is equal to or smaller than the adhesive area of the double-sided adhesive sheet located outside, and the adhesive area of the double-sided adhesive sheet located innermost in the thickness direction of the battery cell is smaller than the adhesive area of the double-sided adhesive sheet located outermost.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a battery pack and a method for manufacturing a battery pack. [Background technology]

[0002] Patent Document 1 discloses a battery pack in which multiple battery cells are stacked in the thickness direction of the battery cells. This battery pack includes a double-sided sheet between every two adjacent battery cells in the thickness direction of the battery cells, which bonds the two battery cells to each other. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-127250 Summary of the Invention [Problem to be solved by the invention]

[0004] In the battery pack described above, the force acting between two adjacent battery cells in the thickness direction of the battery cells varies depending on the position (stacking position) of the two battery cells, while the holding strength of the double-sided adhesive sheet is determined by the adhesive properties and the adhesive area of ​​the double-sided adhesive sheet. Therefore, if two adjacent battery cells are bonded to each other with a double-sided adhesive sheet of the same adhesive area regardless of the positions of the two adjacent battery cells, the holding strength of the double-sided adhesive sheet may be greater than necessary depending on the positions of the two adjacent battery cells. In such cases, the double-sided adhesive sheet is wasted.

[0005] In view of the above circumstances, an object of at least one embodiment of the present invention is to provide a battery assembly in which the adhesive area of ​​at least one double-sided adhesive sheet located on the inner side in the thickness direction of the battery cell can be made smaller than the adhesive area of ​​the double-sided adhesive sheet located on the outermost side, and a method for manufacturing the battery assembly. [Means for solving the problem]

[0006] (1) In at least one embodiment of the present invention, an assembled battery is an assembled battery in which at least four or more battery cells are stacked in the thickness direction of the battery cells, and includes a double-sided adhesive sheet between every two adjacent battery cells in the thickness direction of the battery cells, bonding the two battery cells to each other, the double-sided adhesive sheet having an adhesive area that provides a holding force greater than the product of the total mass of battery cells located inside the double-sided adhesive sheet in the thickness direction of the battery cells and a predetermined impact acceleration, and the adhesive area of ​​the double-sided adhesive sheet located inside the adjacent double-sided adhesive sheets in the thickness direction of the battery cells is equal to or less than the adhesive area of ​​the double-sided adhesive sheet located outside, and the adhesive area of ​​the double-sided adhesive sheet located innermost in the thickness direction of the battery cells is smaller than the adhesive area of ​​the double-sided adhesive sheet located outermost.

[0007] According to the above configuration (1), the adhesive area of ​​at least one of the double-sided adhesive sheets positioned on the inner side in the thickness direction of the battery cell can be made smaller than the adhesive area of ​​the double-sided adhesive sheet positioned on the outermost side.

[0008] (2) In some embodiments, in the configuration of (1) above, the at least four battery cells are at least six battery cells, and at least one of the double-sided adhesive sheets has an adhesive area equal to an adhesive area of ​​the double-sided adhesive sheet located on the outer side of the double-sided adhesive sheets adjacent to the battery cell in the thickness direction.

[0009] According to the above configuration (2), there is no need to use a double-sided adhesive sheet with a different adhesive area for each position of two adjacent battery cells in the thickness direction of the battery cells, and the number of double-sided adhesive sheet items can be reduced.

[0010] (3) In some embodiments, in the configuration of (1) above, the adhesive area of ​​the double-sided adhesive sheet located on the inside of the double-sided adhesive sheets adjacent to each other in the thickness direction of the battery cell is smaller than the adhesive area of ​​the double-sided adhesive sheet located on the outside.

[0011] According to the above configuration (3), the adhesive area of ​​the double-sided adhesive sheets adjacent to each other in the thickness direction of the battery cell can be gradually reduced from the outside toward the inside.

[0012] (4) In some embodiments, in any one of the configurations (1) to (3) above, the double-sided adhesive sheet has an adhesive area such that the pressure on the battery cell due to a load in the thickness direction of the battery cell is equal to or less than a predetermined pressure.

[0013] According to the above configuration (4), the pressure on the battery cells due to the load in the thickness direction of the battery cells is kept below a predetermined pressure, so that short circuits and the like of the battery cells can be prevented.

[0014] (5) In at least one embodiment of the present invention, a method for manufacturing a battery pack is a method for manufacturing a battery pack in which at least four or more battery cells are stacked in the thickness direction of the battery cells, the method comprising the step of installing a double-sided adhesive sheet between every two adjacent battery cells in the thickness direction of the battery cells to bond the two battery cells to each other, wherein the step of installing the double-sided adhesive sheet includes the step of calculating an adhesive area that provides a holding force greater than the product of the total mass of battery cells located more inward than the double-sided adhesive sheet in the thickness direction of the battery cells and a predetermined impact acceleration, the adhesive area being equal to or less than the adhesive area of ​​the double-sided adhesive sheet located outermost in the thickness direction of the battery cells and smaller than the adhesive area of ​​the double-sided adhesive sheet located outermost.

[0015] According to the manufacturing method (5) above, the adhesive area of ​​at least one of the double-sided adhesive sheets positioned on the inner side in the thickness direction of the battery cell can be made smaller than the adhesive area of ​​the double-sided adhesive sheet positioned on the outermost side.

[0016] (6) In some embodiments, in the manufacturing method of (5) above, the adhesive area at which the holding power is obtained is calculated from the relationship between the adhesive area of ​​the double-sided adhesive sheet measured in advance and the holding power of the double-sided adhesive sheet.

[0017] According to the manufacturing method (6) above, it is possible to calculate an adhesive area that can provide a holding force greater than the product of the total mass of the battery cells located inside the double-sided adhesive sheet in the thickness direction of the battery cells and a predetermined impact acceleration. [Effects of the Invention]

[0018] According to at least one embodiment of the battery pack of the present invention, the adhesive area of ​​at least one of the double-sided adhesive sheets located on the inner side in the thickness direction of the battery cell can be made smaller than the adhesive area of ​​the double-sided adhesive sheet located on the outermost side.

[0019] According to at least one embodiment of the manufacturing method for a battery pack of the present invention, the adhesive area of ​​at least one of the double-sided adhesive sheets located on the inner side in the thickness direction of the battery cells can be made smaller than the adhesive area of ​​the double-sided adhesive sheet located on the outermost side. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a diagram schematically illustrating a battery pack according to an embodiment; [Figure 2] FIG. 2 is a diagram schematically illustrating the battery cell shown in FIG. [Figure 3] FIG. 1 is a diagram schematically illustrating a battery pack in which four battery cells are stacked in the thickness direction of the battery cells. [Figure 4] 1 is a diagram schematically illustrating an example of a battery pack in which six battery cells are stacked in the thickness direction of the battery cells. [Figure 5] FIG. 10 is a diagram schematically illustrating another example of a battery pack in which six battery cells are stacked in the thickness direction of the battery cells. [Figure 6] FIG. 10 is a diagram showing the relationship between the adhesive area of ​​a double-sided adhesive sheet and the holding power of the double-sided adhesive sheet. [Figure 7] 3 is a flowchart schematically showing a method for manufacturing a battery pack according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, several embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention. Furthermore, although the height direction of the battery pack is indicated by an arrow in the accompanying drawings, the height direction of the battery pack is merely relative.

[0022] [Battery applications] The battery pack according to the embodiment is mounted on an electric vehicle such as an electric vehicle (BEV), a hybrid vehicle (HV), or a fuel cell vehicle (FCV). Hybrid vehicles include plug-in hybrid vehicles (PHV, PHEV) that can be charged (externally charged) from an external device (e.g., a quick charger) while parked, and plug-in hybrid vehicles (PHEV) that can be externally charged while parked and can supply power (externally power supply) to an external device (e.g., a general household) while parked.

[0023] [Battery pack] As shown in FIG. 1 , the battery assembly 1 according to the embodiment is an assembled battery in which at least four or more battery cells (cells) 10 are stacked in the thickness direction of the battery cells 10. In the battery assembly 1 according to the embodiment, a collar 12 is provided for each battery cell 10. Note that the collars 12 are not an essential component. In addition, in the battery assembly 1 according to the embodiment, a heat transfer plate 14 is provided for every predetermined number of battery cells 10 that are adjacent in the thickness direction of the battery cells 10. Heat generated inside the battery cells 10 is transferred through the heat transfer plate 14 and dissipated to the outside of the battery assembly 1. Note that the heat transfer plate 14 is not an essential component. In the battery assembly 1 according to the embodiment, a double-sided adhesive sheet 16 is provided between every two battery cells 10, 10 that are adjacent in the thickness direction of the battery cells 10, to bond the two battery cells 10, 10 to each other. When a heat transfer plate 14 is provided between two battery cells 10, 10, the double-sided adhesive sheet 16 is composed of two sheets: a sheet 16a that bonds the battery cell 10 to the heat transfer plate 14, and a sheet 16b that bonds the heat transfer plate 14 to the battery cell 10. In the battery pack 1 according to this embodiment, the battery cells 10 stacked in the thickness direction of the battery cells 10 are sandwiched between a pair of pressure plates 18, 18. Note that the pressure plates 18, 18 are not essential components. When the battery cells 10 stacked in the thickness direction of the battery cells 10 are sandwiched between a pair of pressure plates 18, 18, the battery pack 1 has a double-sided adhesive sheet 20 between the battery cells 10 and the pressure plates 18. The surface adhesive sheet 20 bonds the battery cells 10 and the pressure plates 18 to each other.

[0024] The battery pack 1 shown in Fig. 1 has fourteen battery cells 10 stacked in the thickness direction of the battery cells 10, but the number of stacked battery cells 10 is not limited to this. The battery cells 10 that make up the battery pack 1 are lithium ion batteries (secondary batteries) that charge and discharge by the movement of lithium ions between the positive and negative electrodes, but are not limited to this. Although not specifically shown, a lithium ion battery has a separator provided between the positive and negative electrodes, and an electrolyte sealed between the positive and negative electrodes.

[0025] 2, the battery cell 10 according to the embodiment is plate-shaped, with a surface perpendicular to the thickness direction being rectangular (rectangular), but this is not limited thereto. Also, the exterior of the battery cell 10 according to the embodiment is made of a flexible laminate film, and the positive electrode tab 22 and the negative electrode tab 24 extend from one side of the film, but this is not limited thereto.

[0026] The double-sided adhesive sheet 16 is an adhesive sheet having adhesive surfaces on both the front and back surfaces. The shape of the double-sided adhesive sheet 16 is similar to the shape of the surface perpendicular to the thickness direction of the battery cell 10. However, the shape of the double-sided adhesive sheet 16 does not have to be similar to the shape of the surface perpendicular to the thickness direction of the battery cell 10. The double-sided adhesive sheet 16 is arranged so that its center coincides with the center of the surface perpendicular to the thickness direction of the battery cell 10. However, the center of the double-sided adhesive sheet 16 does not have to coincide with the center of the surface perpendicular to the thickness direction of the battery cell 10. In the example shown in FIG. 2 , the double-sided adhesive sheet 16 has a rectangular shape, the same as the shape of the surface perpendicular to the thickness direction of the battery cell 10. Furthermore, the double-sided adhesive sheet 16 is arranged so that its center coincides with the center of the shape of the surface perpendicular to the thickness direction of the battery cell 10.

[0027] The double-sided adhesive sheet 16 according to the embodiment has an adhesive area that provides a holding force greater than the product of the total mass of the battery cells 10 located inside the double-sided adhesive sheet 16 in the thickness direction of the battery cells 10 and a predetermined impact acceleration. When a heat transfer plate 14 is provided between the battery cells 10 located inside the double-sided adhesive sheet 16, the total mass of the battery cells may include the mass of the heat transfer plate 14.

[0028] As shown in FIG. 3 , in an assembled battery 1A in which four battery cells 10A, 10B, 10C, and 10D are stacked in the thickness direction of the battery cells 10, the battery cell 10 located inside the double-sided adhesive sheet 16A provided between the first battery cell 10A and the second battery cell 10B from the bottom is the second battery cell 10B from the bottom. That is, the third battery cell 10C from the bottom (second battery cell from the top) is excluded (the second battery cell 10C from the top is not a battery cell located inside the double-sided adhesive sheet 16A). Therefore, the total mass of the battery cells 10 located inside the double-sided adhesive sheet 16A is the mass of the second battery cell 10B from the bottom. Similarly, the battery cell 10 located inside the double-sided adhesive sheet 16C provided between the first battery cell 10D and the second battery cell 10C from the top is the second battery cell 10C from the top. That is, the third battery cell 10B from the top (second from the bottom) is excluded (the second battery cell 10B from the bottom is not a battery cell located inside the double-sided adhesive sheet 16C). Therefore, the total mass of the battery cells 10 located inside the double-sided adhesive sheet 16C is the mass of the second battery cell 10C from the top.

[0029] 4 and 5, in an assembled battery 1B (1C) in which six battery cells 10E (10L), 10F (10M), 10G (10N), 10H (10P), 10J (10Q), and 10K (10R) are stacked in the thickness direction of the battery cells 10, the battery cells 10 located inside a double-sided adhesive sheet 16E (16L) provided between the first battery cell 10E (10L) and the second battery cell 10F (10M) from the bottom are the second battery cell 10F (10M) and the third battery cell 10G (10N). In other words, the total mass of the battery cells 10 located inside the double-sided adhesive sheet 16E (16L) is the sum of the masses of the second battery cell 10F (10M) from the bottom and the third battery cell 10G (10N) from the bottom. Furthermore, the battery cell 10 located more inward than the double-sided adhesive sheet 16F (16M) provided between the second-to-the-bottom battery cell 10F (10M) and the third-to-the-bottom battery cell 10G (10N) is the third-to-the-bottom battery cell 10G (10N), and the battery cell 10 located more inward than the double-sided adhesive sheet 16F (16M) is the third-to-the-bottom battery cell 10G (10N). In other words, the total mass of the battery cells 10 located more inward than the double-sided adhesive sheet 16F (16M) is the mass of the third-to-the-bottom battery cell 10G (10N).

[0030] The impact acceleration is the acceleration applied to the battery cells 10, and is assumed to be the acceleration applied to the battery pack 1 when an electric vehicle is hit, for example. The acceleration can be set arbitrarily depending on the collision conditions, etc., and the product of the total mass of the battery cells 10 and a predetermined impact acceleration can be regarded as the collision force.

[0031] The holding force is the force required to maintain the relative positions of two adjacent battery cells 10 in the thickness direction of the battery cells 10, and the double-sided adhesive sheet 16 is required to have a holding force greater than the collision force in order to withstand the collision force. The adhesive area of ​​the double-sided adhesive sheet 16 is determined from the relationship between the adhesive area of ​​the double-sided adhesive sheet 16 and the holding force of the double-sided adhesive sheet 16, as shown in Figure 6. The relationship between the adhesive area of ​​the double-sided adhesive sheet 16 and the holding force of the double-sided adhesive sheet 16 can be determined by a verification test, for example, a method of measuring a tensile shear load parallel to the adhesive surface of the double-sided adhesive sheet 16, but the method is not limited to this.

[0032] In the battery pack 1 according to this embodiment, the double-sided adhesive sheet 20 provided between the pressure plate 18 and the battery cells 10 has an adhesive area that provides a holding force greater than the product of the total mass of the battery cells 10 located inside the double-sided adhesive sheet 20 and a predetermined impact acceleration, just like the double-sided adhesive sheets 16 provided between each pair of adjacent battery cells 10 in the thickness direction of the battery cells 10. Note that if a heat transfer plate 14 is provided between the battery cells 10 located inside the double-sided adhesive sheet 20, the total mass of the battery cells may include the mass of the heat transfer plate 14.

[0033] The adhesive area of ​​the double-sided adhesive sheet 20 provided between the pressure plate 18 and the battery cell 10 is equal to or greater than the adhesive area of ​​the double-sided adhesive sheet 16 located at the outermost position in the thickness direction of the battery cell 10. The adhesive area of ​​the double-sided adhesive sheet 20 may be the same as the adhesive area of ​​the double-sided adhesive sheet 16 located at the outermost position in the thickness direction of the battery cell 10, or may be larger than the adhesive area of ​​the double-sided adhesive sheet 16 located at the outermost position in the thickness direction of the battery cell 10.

[0034] Furthermore, the adhesive area of ​​the double-sided adhesive sheet 16 located on the inner side of the double-sided adhesive sheets 16 adjacent to each other in the thickness direction of the battery cell 10 is equal to or smaller than the adhesive area of ​​the double-sided adhesive sheet 16 located on the outer side. With regard to the areas of the double-sided adhesive sheets 16, the adhesive area of ​​the double-sided adhesive sheet 16 located on the innermost side in the thickness direction of the battery cell 10 is smaller than the adhesive area of ​​the double-sided adhesive sheet 16 located on the outermost side. Therefore, the adhesive area of ​​the double-sided adhesive sheet 16 located on the inner side of the double-sided adhesive sheets 16 adjacent to each other in the thickness direction of the battery cell 10 may be the same as the adhesive area of ​​the double-sided adhesive sheet 16 located on the outer side, but the adhesive area of ​​the double-sided adhesive sheet 16 located on the innermost side in the thickness direction of the battery cell 10 is smaller than the adhesive area of ​​the double-sided adhesive sheet 16 located on the outermost side.

[0035] As shown in FIG. 3, the battery pack 1A is formed by stacking four battery cells 10A, 10B, 10C, and 10D in the thickness direction of the battery cell 10. The battery pack 1A has a double-sided adhesive sheet 16A between the first battery cell 10A and the second battery cell 10B from the bottom, a double-sided adhesive sheet 16B between the second battery cell 10B and the third battery cell 10C from the bottom, and a double-sided adhesive sheet 16C between the third battery cell 10C and the fourth battery cell 10D from the bottom. The adhesive area of ​​the double-sided adhesive sheet 16B (the double-sided adhesive sheet 16 located on the inside) is smaller than the adhesive area of ​​the double-sided adhesive sheet 16A (the double-sided adhesive sheet 16 located on the outside) and the adhesive area of ​​the double-sided adhesive sheet 16C (the double-sided adhesive sheet 16 located on the outside). The adhesive area of ​​the double-sided adhesive sheet 16C is equal to the adhesive area of ​​the double-sided adhesive sheet 16A.

[0036] As shown in Fig. 4, the battery pack 1B is formed by stacking at least six battery cells 10E, 10F, 10G, 10H, 10J, and 10K in the thickness direction of the battery cells 10. The battery pack 1B has a double-sided adhesive sheet 16E between the first-lowest battery cell 10E and the second-lowest battery cell 10F, a double-sided adhesive sheet 16F between the second-lowest battery cell 10F and the third-lowest battery cell 10G, a double-sided adhesive sheet 16G between the third-lowest battery cell 10G and the fourth-lowest battery cell 10H, a double-sided adhesive sheet 16H between the fourth-lowest battery cell 10H and the fifth-lowest battery cell 10J, and a double-sided adhesive sheet 16J between the fifth-lowest battery cell 10J and the sixth-lowest battery cell 10K. At least one of the double-sided adhesive sheets 16 of the battery pack 1B has the same adhesive area as the adhesive area of ​​the outermost double-sided adhesive sheet 16 between adjacent double-sided adhesive sheets 16 in the thickness direction of the battery cells 10. 4, the adhesive areas of double-sided adhesive sheets 16F, 16G, and 16H are the same. Also, the adhesive areas of double-sided adhesive sheets 16E and 16J are the same. Furthermore, the adhesive areas of double-sided adhesive sheets 16F, 16G, and 16H (double-sided adhesive sheets 16 located on the inside) are smaller than the adhesive areas of double-sided adhesive sheets 16E and 16J (double-sided adhesive sheets 16 located on the outside).

[0037] 5, the battery pack 1C is formed by stacking at least six battery cells 10L, 10M, 10N, 10P, 10Q, and 10R in the thickness direction of the battery cells 10. The battery pack 1C has a double-sided adhesive sheet 16L between the first-lowest battery cell 10L and the second-lowest battery cell 10M, a double-sided adhesive sheet 16M between the second-lowest battery cell 10M and the third-lowest battery cell 10N, a double-sided adhesive sheet 16N between the third-lowest battery cell 10N and the fourth-lowest battery cell 10P, a double-sided adhesive sheet 16P between the fourth-lowest battery cell 10P and the fifth-lowest battery cell 10Q, and a double-sided adhesive sheet 16Q between the fifth-lowest battery cell 10Q and the sixth-lowest battery cell 10R. In the battery pack 1C, the adhesive area of ​​the double-sided adhesive sheet 16 located on the inner side of adjacent double-sided adhesive sheets 16 in the thickness direction of the battery cells 10 is smaller than the adhesive area of ​​the double-sided adhesive sheet 16 located on the outer side. In the example shown in FIG. 5, the adhesive area of ​​double-sided adhesive sheet 16N (double-sided adhesive sheet 16 located on the inside) is smaller than the adhesive areas of double-sided adhesive sheet 16M and double-sided adhesive sheet 16P (double-sided adhesive sheets 16 located on the outside). The adhesive area of ​​double-sided adhesive sheet 16M is equal to the adhesive area of ​​double-sided adhesive sheet 16P. Furthermore, the adhesive areas of double-sided adhesive sheet 16M and double-sided adhesive sheet 16P (double-sided adhesive sheets 16 located on the inside) are smaller than the adhesive areas of double-sided adhesive sheet 16L and double-sided adhesive sheet 16Q (double-sided adhesive sheets 16 located on the outside).

[0038] The double-sided adhesive sheet 16 has an adhesive area such that the pressure on the battery cells 10 due to a load in the thickness direction of the battery cells 10 is equal to or less than a predetermined pressure. The load in the thickness direction of the battery cells 10 is set based on the load acting on the assembled battery. The predetermined pressure is a pressure required to prevent the battery cells 10 from shorting out, and is set, for example, based on the results of a verification test. This determines the minimum adhesive area of ​​the double-sided adhesive sheet 16.

[0039] [Battery assembly effect] According to the battery pack 1 of embodiment 1, the adhesive area of ​​at least one of the double-sided adhesive sheets 16 located on the inner side in the thickness direction of the battery cells 10 can be made smaller than the adhesive area of ​​the double-sided adhesive sheet 16 located on the outermost side.

[0040] In the example shown in Figure 3, the adhesive area of ​​the double-sided adhesive sheet 16B located between the second-lowest battery cell 10B and the third-lowest battery cell 10C can be made smaller than the adhesive area of ​​the double-sided adhesive sheet 16A located between the first-lowest battery cell 10A and the second-lowest battery cell 10B and the adhesive area of ​​the double-sided adhesive sheet 16C located between the third-lowest battery cell 10C and the fourth-lowest battery cell 10D.

[0041] In the example shown in FIG. 4 , the adhesive area of ​​the double-sided adhesive sheet 16G located between the third battery cell 10G and the fourth battery cell 10H from the bottom is the same as the adhesive area of ​​the double-sided adhesive sheet 16F located between the second battery cell 10F and the third battery cell 10G from the bottom, and the adhesive area of ​​the double-sided adhesive sheet 16H located between the fourth battery cell 10H and the fifth battery cell 10J from the bottom. Therefore, there is no need to use double-sided adhesive sheets 16 with different adhesive areas for each position of two adjacent battery cells 10 in the thickness direction of the battery cells 10, and the number of types of double-sided adhesive sheets 16 can be reduced.

[0042] In the example shown in FIG. 5 , the adhesive area of ​​the double-sided adhesive sheet 16N located between the third battery cell 10N and the fourth battery cell 10P from the bottom is smaller than the adhesive area of ​​the double-sided adhesive sheet 16M located between the second battery cell 10M and the third battery cell 10N and the adhesive area of ​​the double-sided adhesive sheet 16P located between the fourth battery cell 10P and the fifth battery cell 10Q from the bottom, and the adhesive areas of the double-sided adhesive sheet 16M located between the second battery cell 10M and the third battery cell 10N and the adhesive area of ​​the double-sided adhesive sheet 16P located between the fourth battery cell 10P and the fifth battery cell 10Q from the bottom are smaller than the adhesive area of ​​the double-sided adhesive sheet 16L located between the first battery cell 10L and the second battery cell 10M and the adhesive area of ​​the double-sided adhesive sheet 16Q located between the fifth battery cell 10Q and the sixth battery cell 10R from the bottom.

[0043] Furthermore, in the battery pack 1, the pressure on the battery cells 10 due to the load in the thickness direction of the battery cells 10 is equal to or less than a predetermined pressure. Therefore, the battery pack 1 can prevent short circuits and the like of the battery cells 10.

[0044] [Manufacturing method of assembled battery] The manufacturing method of the battery assembly 1 according to the embodiment is a manufacturing method of a battery assembly in which at least four or more battery cells 10 are stacked in the thickness direction of the battery cells 10. The manufacturing method of the battery assembly 1 includes a step (S10) of placing a double-sided adhesive sheet 16 between every two battery cells 10 adjacent to each other in the thickness direction of the battery cells 10 to bond the two battery cells 10 to each other.

[0045] The step (S10) of installing the double-sided adhesive sheet 16 includes a step (S12) of calculating an adhesive area that provides a holding force greater than the product of the total mass of the battery cells 10 located inside the double-sided adhesive sheet 16 in the thickness direction of the battery cells 10 and a predetermined impact acceleration, is equal to or smaller than the adhesive area of ​​the double-sided adhesive sheet 16 located outside of the double-sided adhesive sheets 16 adjacent to each other in the thickness direction of the battery cells 10, and is smaller than the adhesive area of ​​the double-sided adhesive sheet 16 located innermost in the thickness direction of the battery cells 10. The total mass of the battery cells 10 located inside the double-sided adhesive sheet 16 in the thickness direction of the battery cells 10 and the predetermined impact acceleration are the same as those described for the battery pack.

[0046] The adhesive area at which a holding force can be obtained is calculated from the relationship between the adhesive area of ​​the double-sided adhesive sheet 16 measured in advance and the holding force of the double-sided adhesive sheet 16. The relationship between the adhesive area of ​​the double-sided adhesive sheet 16 and the holding force of the double-sided adhesive sheet 16 is the same as that described for the battery pack.

[0047] [Battery assembly manufacturing method effects] According to the manufacturing method of the battery pack 1 of the embodiment, the adhesive area of ​​at least one of the double-sided adhesive sheets 16 located on the inner side in the thickness direction of the battery cell 10 can be made smaller than the adhesive area of ​​the double-sided adhesive sheet 16 located on the outermost side.

[0048] The present invention is not limited to the above-described embodiments, and includes modifications to the above-described embodiments and appropriate combinations of these modifications. [Explanation of symbols]

[0049] 1 battery pack 10, 10A~10D, 10E~10K, 10L~10R battery cells 12 colors 14 Heat transfer plate 16, 16A~16C, 16E~16J, 16L~16Q double-sided adhesive sheet 16a, 16b seats 18 Pressure plate 20 double-sided adhesive sheet 22 Positive electrode tab 24 Negative electrode tab

Claims

1. A battery pack in which at least four battery cells are stacked in the thickness direction of the battery cells, a double-sided adhesive sheet for adhering the two battery cells to each other between each two adjacent battery cells in a thickness direction of the battery cells; the double-sided adhesive sheet has an adhesive area that provides a holding force greater than the product of the total mass of battery cells located more inward than the double-sided adhesive sheet in the thickness direction of the battery cells and a predetermined impact acceleration, and the adhesive area of ​​the double-sided adhesive sheet located innermost in the thickness direction of the battery cells is equal to or less than the adhesive area of ​​the double-sided adhesive sheet located outermost, and the adhesive area of ​​the double-sided adhesive sheet located innermost in the thickness direction of the battery cells is smaller than the adhesive area of ​​the double-sided adhesive sheet located outermost.

2. The at least four battery cells are at least six battery cells, 2. The battery pack according to claim 1, wherein at least one of the double-sided adhesive sheets has an adhesive area equal to an adhesive area of ​​an outermost double-sided adhesive sheet of the double-sided adhesive sheets adjacent to each other in the thickness direction of the battery cell.

3. 2. The battery pack according to claim 1, wherein the adhesive area of ​​the double-sided adhesive sheet positioned inside the adjacent double-sided adhesive sheets in the thickness direction of the battery cells is smaller than the adhesive area of ​​the double-sided adhesive sheet positioned outside.

4. The battery pack according to claim 1 , wherein the double-sided adhesive sheet has an adhesive area such that a pressure on the battery cell due to a load in a thickness direction of the battery cell is equal to or less than a predetermined pressure.

5. A method for manufacturing a battery pack in which at least four battery cells are stacked in a thickness direction of the battery cells, a step of placing a double-sided adhesive sheet between two adjacent battery cells in a thickness direction of the battery cells to bond the two battery cells to each other; the step of installing the double-sided adhesive sheets includes a step of calculating an adhesive area such that a holding force greater than the product of a total mass of battery cells located more inward than the double-sided adhesive sheets in the thickness direction of the battery cells and a predetermined impact acceleration is obtained, the adhesive area is equal to or less than the adhesive area of ​​the double-sided adhesive sheet located outermost in the thickness direction of the battery cells among the double-sided adhesive sheets adjacent to each other in the thickness direction of the battery cells, and the adhesive area of ​​the double-sided adhesive sheet located innermost in the thickness direction of the battery cells is smaller than the adhesive area of ​​the double-sided adhesive sheet located outermost.

6. The method for manufacturing a battery pack according to claim 5 , wherein the adhesive area at which the holding force is obtained is calculated from a relationship between a previously measured adhesive area of ​​the double-sided adhesive sheet and the holding force of the double-sided adhesive sheet.

Images