Heat dissipation structure and battery module

Abstract

To improve the heat dissipation capability of battery cells while suppressing the positional deviation of the battery cells.SOLUTION: A heat dissipation structure 1 comprises: a battery cell 11 having an electrode body 111 and an outer package 112 for accommodating the electrode body 111; a cooler 12 that is located so as to face a bottom face 112A of the outer package 112; and a heat dissipation material 13 which is located between the bottom face 112A and the cooler 12 and is in contact with the bottom face 112A and the cooler 12. The bottom face 112A is deformed in a convex form to the cooler 12 side by heat generated by the electrode body 111, and a heat dissipation material 13 includes a first member 131 having a first elongation rate, and a second member 132 having a second elongation rate higher than the first elongation rate. The first member 131 is located at a position which is at least in contact with an apex 112A1 of the bottom face 112A that is deformed in the convex form, and the second member 132 is located at a position which is adjacent to the first member 131 and in contact with a recess 112A2 whose amount of deformation to the cooler 12 side is smaller than that of the apex 112A1 of the bottom face 112A.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a heat dissipation structure and a battery module. [Background technology]

[0002] A battery pack mounted on a vehicle includes a battery module, and the battery module includes a plurality of battery cells. The lower surface of the battery cell is cooled by a cooler. A heat dissipation material disposed between the lower surface of the battery cell and the upper surface of the cooler has a role of conducting heat from the battery cell to the cooler. When one of the plurality of battery cells included in the battery module generates abnormal heat, it becomes important to transmit heat from the abnormally heated battery cell to the cooler via the heat dissipation material in order to suppress the transmission of heat to the battery cells adjacent to the abnormally heated battery cell. When the vehicle is moving forward, a load called an external input (e.g., a load in the front-rear direction of the vehicle) may be applied to the battery pack due to the contact of the front guard of the vehicle with a ground object such as a curb. In order to suppress the positional deviation of the battery cell with respect to the cooler, for example, in the front-rear direction of the vehicle, when the external input is applied to the battery pack, a heat dissipation material having a predetermined hardness is used. Patent Document 1 discloses a curable thermally conductive grease that efficiently transfers heat radiated from a heating element to a heat sink even when the distance between the heating element and the heat sink is large. In the technology described in Patent Document 2, dot-like portions called wafer portions formed from a heat dissipating material with a high content of heat dissipating filler are arranged in a scattered manner in a direction perpendicular to the thickness direction of the sheet (i.e., in the surface direction of the sheet), and the multiple wafer portions are arranged side by side on the same line in the thickness direction of the sheet. That is, in the technology described in Patent Document 2, the multiple wafer portions are arranged like islands in the surface direction of the sheet, and the multiple wafer portions are arranged side by side in the thickness direction of the sheet at the respective positions of the multiple wafer portions scattered in the surface direction of the sheet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2015 / 092889 [Patent Document 2] JP 2013-080916 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the case of a sheet-type heat dissipation material such as that described in Patent Document 2, the adhesiveness of the heat dissipation material is low, so the heat dissipation material cannot follow the expansion of the battery cell when abnormal heat is generated, and there is a risk that the heat dissipation material will peel off from the battery cell. In the case of a hardening type heat dissipation material such as that described in Patent Document 1, the heat dissipation material is hard and inelastic after hardening, so the heat dissipation material cannot follow the expansion of the battery cell when abnormal heat is generated, and there is a risk that the heat dissipation material will peel off from the battery cell. As a result, in the cases of the techniques described in Patent Documents 1 and 2, when the battery cell becomes hot, the heat generated by the battery cell cannot be sufficiently conducted to the cooler, and there is a risk that heat dissipation will be insufficient.

[0005] In view of the above, an object of the present disclosure is to provide a heat dissipation structure and a battery module that can improve the heat dissipation performance of a battery cell while suppressing misalignment of the battery cell. [Means for solving the problem]

[0006] (1) One aspect of the present disclosure is a heat dissipation structure comprising: a battery cell having an electrode body and an exterior body that houses the electrode body; a cooler arranged to face a bottom surface of the exterior body; and a heat dissipation material arranged between the bottom surface and the cooler and in contact with the bottom surface and the cooler, wherein the bottom surface is deformed in a convex shape toward the cooler and the heat dissipation material due to heat generated by the electrode body, and the heat dissipation material comprises a first member having a first elongation rate and a second member having a second elongation rate higher than the first elongation rate, wherein the first member is arranged at a position where it abuts at least an apex of the convexly deformed bottom surface, and the second member is arranged at a position adjacent to the first member and where it abuts a recess that is a portion of the bottom surface that deforms less toward the cooler than the apex.

[0007] (3) One aspect of the present disclosure is a battery module having the heat dissipation structure of (1), in which a plurality of the battery cells are arranged in a row, the top of each of the plurality of battery cells abuts the first member, and the recess of each of the plurality of battery cells abuts the second member. Effect of the Invention

[0008] According to the present disclosure, it is possible to improve the heat dissipation performance of the battery cells while suppressing misalignment of the battery cells. [Brief description of the drawings]

[0009] [Figure 1] 2A to 2C are diagrams illustrating an example of a battery cell that constitutes a part of the heat dissipation structure of the first embodiment. [Diagram 2] 13 is a diagram showing an example of a battery cell in a state in which the bottom surface of the exterior body is deformed into a convex shape due to heat generation from the electrode body. FIG. [Diagram 3] FIG. 2 is a diagram illustrating an example of a heat dissipation structure according to the first embodiment. [Figure 4] 4 is a diagram showing the heat dissipation structure etc. of the first embodiment in a state in which the bottom surface of the exterior body of the battery cell is deformed into a convex shape due to heat generation from the electrode body of the battery cell. FIG. [Diagram 5]4A to 4C are diagrams for explaining an example of the heat dissipation structure of the first embodiment when an external input is applied. [Figure 6] FIG. 11 is a diagram illustrating an example of a battery module according to a second embodiment. [Figure 7] FIG. 11 is a diagram for explaining the apex, recesses, etc. of the bottom surface of the exterior body of multiple battery cells when the bottom surface of the exterior body of multiple battery cells is deformed into a convex shape due to heat generation from the electrode body of multiple battery cells included in the battery module of the second embodiment. [Figure 8] FIG. 13 is a graph showing the relationship between the area ratio of a first member and the shear adhesive strength of the first member. [Figure 9] FIG. 13 is a diagram showing the relationship between the area ratio of the second member and the shear adhesive strength of the second member. [Figure 10] 10 is a diagram showing the relationship between the contact area retention rate between the bottom surface of the exterior body of the battery cell and the first member and the amount of heat transferred to a cooler via the first member. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of a heat dissipation structure and a battery module according to the present disclosure will be described with reference to the drawings.

[0011] First Embodiment Fig. 1 is a diagram that shows an example of a battery cell 11 that constitutes a part of the heat dissipation structure 1 (see Fig. 3) of the first embodiment. In detail, Fig. 1 shows an example of a battery cell 11 in a state where no deformation occurs in the bottom surface 112A of the exterior body 112 of the battery cell 11 due to heat generation from the electrode body 111 of the battery cell 11. Fig. 2 shows an example of a battery cell 11 in a state where the bottom surface 112A of the exterior body 112 is deformed into a convex shape due to heat generation from the electrode body 111. Fig. 3 is a diagram that shows an example of the heat dissipation structure 1 of the first embodiment. In detail, Figure 3(A) is a side view of an example of the heat dissipation structure 1 of the first embodiment in a state in which there is no deformation of the bottom surface 112A of the exterior body 112 due to heat generation by the electrode body 111, Figure 3(B) is a top view of the heat dissipation material 13 shown in Figure 3(A) with the battery cell 11 seen through (the outline of the battery cell 11 is shown by a dashed line), and Figure 3(C) is a top view of the battery cell 11 and heat dissipation material 13 shown in Figure 3(A).

[0012] 1 to 3, a heat dissipation structure 1 of the first embodiment includes a battery cell 11, a cooler 12, and a heat dissipation material 13. The battery cell 11 is, for example, a lithium ion battery, a nickel-metal hydride battery, an all-solid-state battery, a lead battery, or the like.

[0013] The battery cell 11 has an electrode body 111 and an exterior body 112. The electrode body 111 has a positive electrode and a negative electrode. In detail, the electrode body 111 is composed of a positive electrode active material, a negative electrode active material, a positive electrode current collector, a negative electrode current collector, a separator, and the like. The exterior body 112 accommodates the electrode body 111 and an electrolyte, and has, for example, a rectangular shape. The exterior body 112 is composed of a metal material with good thermal conductivity. Examples of such metal materials include aluminum, stainless steel, and nickel-plated steel. The walls constituting the exterior body 112 are composed of wide side wall portions formed at both ends of the thickness direction of the battery cell 11 (left and right direction in FIG. 1), narrow side wall portions formed at both ends of the width direction of the battery cell 11 (up and down direction in FIG. 3(C)), an upper wall portion (lid portion), and a bottom wall portion. A positive electrode terminal electrically connected to the positive electrode of the electrode body 111 and a negative electrode terminal electrically connected to the negative electrode of the electrode body 111 are provided on the upper wall of the exterior body 112 . The cooler 12 is disposed to face the bottom surface 112A of the exterior body 112 (i.e., the lower surface of the bottom wall portion of the exterior body 112), and cools the battery cells 11. The cooler 12 is, for example, a cooling plate equipped with piping through which a refrigerant (e.g., air, cooling liquid, etc.) flows. In other examples, the cooler 12 may not include refrigerant piping, such as a heat sink, heat dissipation fins, etc.

[0014] In the example shown in FIGS. 1 to 3, the heat dissipation material 13 is disposed between the bottom surface 112A of the exterior body 112 of the battery cell 11 and the cooler 12. The heat dissipation material 13 abuts against the bottom surface 112A of the exterior body 112 of the battery cell 11 and also abuts against the cooler 12. The heat dissipation material 13 functions as a heat transfer member, and heat generated by the electrode body 111 of the battery cell 11 is conducted to the cooler 12 via the heat dissipation material 13. The heat dissipation material 13 includes a first member 131 having a first elongation rate and a second member 132 having a second elongation rate higher than the first elongation rate. The hardness of the first member 131 is higher than the hardness of the second member 132, and the adhesive strength of the first member 131 is higher than the adhesive strength of the second member 132.

[0015] 1 to 3, the characteristics of the first member 131 are that the thermal conductivity of the first member 131 is 3.0 [W / mK] or more, the hardness (Asker C: Asker hardness scale C type) of the first member 131 is 85 to 95, the adhesive strength of the first member 131 is 1.3 [MPa] or more, and the elongation rate of the first member 131 is 10 [%] or more (less than 20 [%]). The characteristics of the second member 132 are that the thermal conductivity of the second member 132 is 3.0 [W / mK] or more, the hardness (Asker C: Asker hardness scale C type) of the second member 132 is 10 or less, the adhesive strength of the second member 132 is 0.01 [MPa] or more (less than 1.3 [MPa]), and the elongation rate of the second member 132 is 20 [%] or more. In other examples, the characteristics of the first member 131 and the characteristics of the second member 132 may be different from those described above.

[0016] 1 to 3, bottom surface 112A of exterior body 112 of battery cell 11 is deformed in a convex shape toward cooler 12 and heat dissipation material 13 (the lower side in FIG. 2) as shown in FIG. 2 due to heat generated by electrode body 111. In other words, as shown in FIG. 2, when bottom surface 112A is deformed in a convex shape, bottom surface 112A has top portion 112A1 and recessed portion 112A2 which is a portion that is less deformed (protrudes) toward cooler 12 (the lower side in FIG. 2) than top portion 112A1. 1 to 3, the first member 131 of the heat dissipation material 13 is disposed at a position where it abuts at least the top 112A1 of the bottom surface 112A of the exterior body 112 of the battery cell 11 that deforms into a convex shape as the electrode body 111 of the battery cell 11 generates heat. Furthermore, the second member 132 of the heat dissipation material 13 is disposed at a position adjacent to the first member 131 of the heat dissipation material 13 and where it abuts against the concave portion 112A2 of the bottom surface 112A of the exterior body 112 of the battery cell 11.

[0017] Specifically, in the example shown in FIG. 1 to FIG. 3, the first member 131 and the second member 132 of the heat dissipation material 13 are hardening type heat dissipation materials. A method using a general dispenser can be adopted as a method for applying the first member 131 and the second member 132 of the heat dissipation material 13 to the cooler 12. In particular, it is preferable to mix two liquids, a base agent and a hardener, immediately before application. This is because, since the two liquids are mixed immediately before application, they are unlikely to harden during the application process, are easy to store, and can be quickly hardened after application. In the heat dissipation structure 1 of the first embodiment, the first member 131 and the second member 132 are used as the heat dissipation material 13 (that is, two types of materials are used as the heat dissipation material 13), it is preferable to apply them in the order of applying one of the first member 131 and the second member 132 with a dispenser and then applying the other of the first member 131 and the second member 132.

[0018] It is preferable that the sum of the contact area between the first member 131 and the bottom surface 112A of the exterior body 112 of the battery cell 11 and the contact area between the second member 132 and the bottom surface 112A of the exterior body 112 of the battery cell 11 is 90% or more of the entire area of ​​the bottom surface 112A of the exterior body 112 of the battery cell 11.

[0019] Fig. 4 is a diagram showing the heat dissipation structure 1 of the first embodiment etc. in a state in which the bottom surface 112A of the exterior body 112 of the battery cell 11 is deformed into a convex shape due to heat generation from the electrode body 111 of the battery cell 11. In detail, Fig. 4(A) shows an example of the heat dissipation structure 1 of the first embodiment in a state in which the bottom surface 112A of the exterior body 112 of the battery cell 11 is deformed into a convex shape due to heat generation from the electrode body 111 of the battery cell 11, and Fig. 4(B) shows the heat dissipation structure R1 of the comparative example in a state in which the bottom surface of the exterior body R112 of the battery cell R11 is deformed into a convex shape due to heat generation from the electrode body R111 of the battery cell R11. 4(B), the hardness (Asker C: Asker hardness scale type C) of the heat dissipation material R13 is 80, and the heat dissipation material R13 is hard, so that the heat dissipation material R13 cannot follow the deformation of the bottom surface of the exterior body R112 of the battery cell R11 caused by heat generation of the electrode body R111 of the battery cell R11, and the heat dissipation material R13 peels off from the bottom surface of the exterior body R112 of the battery cell R11. As a result, the contact area between the bottom surface of the exterior body R112 of the battery cell R11 and the heat dissipation material R13 becomes small, and the heat generated by the battery cell R11 cannot be sufficiently conducted to the cooler R12, which may result in insufficient heat dissipation. 4(A), the hardness (Asker C: Asker hardness scale type C) of the second member 132 of the heat dissipation material 13 is 10 or less, and the second member 132 of the heat dissipation material 13 is soft, so that the second member 132 of the heat dissipation material 13 can follow the deformation of the bottom surface 112A of the exterior body 112 of the battery cell 11 associated with heat generation of the electrode body 111 of the battery cell 11 without peeling off from the recess 112A2 of the bottom surface 112A of the exterior body 112 of the battery cell 11. In other words, the second member 132 of the heat dissipation material 13 can have a complementary shape to the recess 112A2 of the bottom surface 112A of the exterior body 112 of the battery cell 11 after deformation associated with heat generation of the electrode body 111 of the battery cell 11. Therefore, the contact area between the bottom surface 112A of the exterior body 112 of the battery cell 11 and the first member 131 and the second member 132 of the heat dissipation material 13 is maintained without being reduced. As a result, the heat generated by the battery cell 11 can be sufficiently conducted to the cooler 12, and the heat can be dissipated appropriately.

[0020] In one example of the heat dissipation structure 1 of the first embodiment, as shown in Figure 4 (A), in order for the second member 132 of the heat dissipation material 13 to follow the deformation of the bottom surface 112A of the exterior body 112 of the battery cell 11 due to heat generation from the electrode body 111 of the battery cell 11, it is preferable that the contact area between the second member 132 and the bottom surface 112A of the exterior body 112 of the battery cell 11 be 50% or more of the entire area of ​​the bottom surface 112A of the exterior body 112 of the battery cell 11.

[0021] Fig. 5 is a diagram for explaining an example of the heat dissipation structure 1 of the first embodiment when an external input is applied. In detail, Fig. 5(A) is a diagram for explaining an example of the heat dissipation structure 1 of the first embodiment when an external input is applied, and Fig. 5(B) is a diagram for explaining the heat dissipation structure R1 of the comparative example when an external input is applied. In the comparative example shown in Fig. 5(B), when an external input is applied to the heat dissipation structure R1 of the comparative example and an inertial force indicated by a rightward arrow in Fig. 5(B) is generated in the battery cell R11, the large adhesive force of the heat dissipation material R13 prevents the battery cell R11 from shifting in position to the right in Fig. 5(B) relative to the cooler R12. In the comparative example shown in Fig. 5(B), the hardness (Asker C: Asker rubber hardness scale type C) of the heat dissipation material R13 is 80, similar to the comparative example shown in Fig. 4(B). In the example shown in Figure 5(A), when an external input is applied to the heat dissipation structure 1 of the first embodiment, and an inertial force indicated by a rightward arrow in Figure 5(A) is generated in the battery cell 11, the large adhesive force of the first member 131 of the heat dissipation material 13 prevents the battery cell 11 from shifting in position to the right in Figure 5(A) relative to the cooler 12.

[0022] In one example of the heat dissipation structure 1 of the first embodiment, as shown in FIG. 5(A), in order to prevent the battery cell 11 from shifting in position relative to the cooler 12 to the right in FIG. 5(A) when an external input is applied to the heat dissipation structure 1 of the first embodiment, it is preferable that the contact area between the first member 131 and the bottom surface 112A of the exterior body 112 of the battery cell 11 be 37% or more of the entire area of ​​the bottom surface 112A of the exterior body 112 of the battery cell 11.

[0023] In one example of the heat dissipation structure 1 of the first embodiment, it is preferable that the ratio of the area of ​​the contact surface between the first member 131 of the heat dissipation material 13 and the cooler 12 to the area of ​​the contact surface between the second member 132 of the heat dissipation material 13 and the cooler 12 is, for example, 4 / 6 to 6 / 4.

[0024] In one example of the heat dissipation structure 1 of the first embodiment, aluminum hydroxide and / or aluminum oxide is preferably used as a filler that ensures the thermal conductivity of the first member 131 and the second member 132 of the heat dissipation material 13. Aluminum hydroxide and aluminum oxide have high thermal conductivity and low specific gravity, and therefore can suppress separation of the filler from the resin component as a filler contained in the first member 131 and the second member 132. In addition, the shape of the filler contained in the first member 131 and the second member 132 is preferably spherical so as to enable high filling and not reduce fluidity.

[0025] In one example of the heat dissipation structure 1 of the first embodiment, the resin component serving as a filler contained in the first member 131 and the second member 132 of the heat dissipation material 13 is preferably an addition reaction type liquid polymer. The addition reaction type liquid polymer has small shrinkage upon curing. When the first member 131 and the second member 132 of the heat dissipation material 13 harden while being sandwiched between the battery cell 11 and the cooler 12, if the hardening shrinkage of the first member 131 and the second member 132 is large, gaps may occur between the battery cell 11 and the first member 131 and the second member 132, or between the cooler 12 and the first member 131 and the second member 132. In view of this, in one example of the heat dissipation structure 1 of the first embodiment, the resin component as a filler contained in the first member 131 and the second member 132 is an addition reaction type liquid polymer, and has small shrinkage upon curing. Therefore, it is possible to suppress gaps occurring between the battery cell 11 and the first member 131 and the second member 132, and to suppress gaps occurring between the cooler 12 and the first member 131 and the second member 132. Examples of the addition reaction type liquid polymer used for the resin component as a filler contained in the first member 131 and the second member 132 of the heat dissipation material 13 include polyurethane, epoxy resin, olefin-based polymer, silicone, etc.

[0026] In one example of the heat dissipation structure 1 of the first embodiment, a dispersant, a flame retardant, a coupling agent, a plasticizer, an antioxidant, a colorant, a catalyst, and the like may be added to the curable heat dissipation material 13. When the above-mentioned substances are added to the curable heat dissipation material 13, the above-mentioned substances are mixed into the curable heat dissipation material 13 to produce the curable heat dissipation material 13 to which the above-mentioned substances have been added.

[0027] 4(A) and 5(A), the heat dissipation material 13 includes a first member 131 having a first elongation rate and a second member 132 having a second elongation rate higher than the first elongation rate, the hardness of the first member 131 is higher than the hardness of the second member 132, and the adhesive strength of the first member 131 is higher than the adhesive strength of the second member 132. Therefore, when the electrode body 111 of the battery cell 11 generates (abnormal) heat, the second member 132 having the second elongation rate higher than the first elongation rate (i.e., the soft second member 132) follows the deformation of the bottom surface 112A of the exterior body 112 of the battery cell 11 that accompanies the heat generation of the electrode body 111 of the battery cell 11, and abuts against the recess 112A2 of the bottom surface 112A of the exterior body 112 of the battery cell 11. Furthermore, when an external input is applied to the heat dissipation structure 1, the high hardness and strong adhesive strength of the first member 131 can prevent the battery cell 11 from shifting in position relative to the cooler 12 to the right in Figure 5(A). In other words, in one example of the heat dissipation structure 1 of the first embodiment, it is possible to simultaneously satisfy the physical properties of the heat dissipation material 13 required when the electrode body 111 of the battery cell 11 generates (abnormal) heat, and the physical properties of the heat dissipation material 13 required when an external input is applied to the heat dissipation structure 1.

[0028] In the examples shown in Figures 3(A) to 3(C), 4(A) and 5(A), the heat dissipation material 13 has second members 132 on both sides of a central first member 131, but in other examples, the heat dissipation material 13 may have second members 132 on only one side of the central first member 131.

[0029] <Second embodiment> The heat dissipation structure 1 included in the battery module M of the second embodiment is configured similarly to the heat dissipation structure 1 of the above-described first embodiment, except for the points that will be described later.

[0030] Fig. 6 is a diagram that illustrates an example of a battery module M of the second embodiment. In detail, Fig. 6 illustrates a state in which no deformation occurs in the bottom surface 112A of the exterior body 112 of the multiple battery cells 11 (11-1, 11-2) associated with heat generation from the electrode body 111 of the multiple battery cells 11 included in the battery module M of the second embodiment. Fig. 7 is a diagram for explaining the top portion 112A1, the recessed portion 112A2, etc. of the bottom surface 112A of the exterior body 112 in a state in which the bottom surface 112A of the exterior body 112 of the multiple battery cells 11 is deformed into a convex shape associated with heat generation from the electrode body 111 of the multiple battery cells 11 included in the battery module M of the second embodiment. In detail, Figure 7(A) shows the tops 112A1 (112A1-1, 112A1-2) and recesses 112A2 (112A21-1, 112A22-1, 112A21-2, 112A22-2) of the bottom surface 112A (112A-1, 112A-2) of the exterior body 112 when the bottom surface 112A of the exterior body 112 of the multiple battery cells 11 is deformed into a convex shape due to heat generation by the electrode body 111 of the multiple battery cells 11 included in the battery module M of the second embodiment. Figure 7(B) shows the first members 131 (131-1, 131-2) and second members 132 (132-1, 132-2, 132-3) of the heat dissipation material 13 in a state in which the bottom surface 112A of the outer casing 112 of the multiple battery cells 11 has been deformed into a convex shape due to heat generation from the electrode body 111 of the multiple battery cells 11 included in the battery module M of the second embodiment.

[0031] In the examples shown in Figs. 6 and 7, a battery module M of the second embodiment has the heat dissipation structure 1 shown in Fig. 3(A). The battery module M includes a plurality of battery cells 11, a cooler 12 for cooling the plurality of battery cells 11, a heat dissipation material 13 arranged between the plurality of battery cells 11 and the cooler 12, and an end plate M1. The plurality of battery cells 11 are arranged side by side. The heat insulating material M2 has a function of suppressing the transfer of heat generated by one of the plurality of battery cells 11, for example, when the battery cell 11 abnormally heats up, to another adjacent battery cell 11. The heat generated by the battery cell 11 is released to the cooler 12 via the heat dissipation material 13.

[0032] 7(A), in a battery module M of the second embodiment, when the bottom surface 112A of the exterior body 112 of the multiple battery cells 11 is deformed into a convex shape due to heat generation from the electrode body 111 of the multiple battery cells 11, the top portions 112A1 (112A1-1, 112A1-2) of the multiple battery cells 11 abut against the first members 131 of the heat dissipation material 13. That is, in the example shown in FIGS. 6 and 7, the heat dissipation material 13 has the same number of first members 131 as the multiple battery cells 11. Furthermore, in the battery module M of the second embodiment, as shown in Figures 7(A) and 7(B), when the bottom surface 112A of the exterior body 112 of the multiple battery cells 11 is deformed into a convex shape due to heat generation from the electrode body 111 of the multiple battery cells 11, each of the recesses 112A2 (112A21-1, 112A22-1, 112A21-2, 112A22-2) on the bottom surface 112A of the exterior body 112 of the multiple battery cells 11 abuts against the second member 132 of the heat dissipation material 13.

[0033] 6 and 7, the multiple battery cells 11 included in the battery module M include a first battery cell 11-1 and a second battery cell 11-2 arranged next to the first battery cell 11-1. As shown in Fig. 7(A), the bottom surface 112A-1 of the first battery cell 11-1 includes a top 112A1-1 of the first battery cell 11-1, a first recess 112A21-1 of the first battery cell 11-1 located on the opposite side to the second battery cell 11-2 from the top 112A1-1 of the first battery cell 11-1 (left side in Fig. 7(A)), and a second recess 112A22-1 of the first battery cell 11-1 located on the second battery cell 11-2 side from the top 112A1-1 of the first battery cell 11-1 (right side in Fig. 7(A)). The bottom surface 112A-2 of the second battery cell 11-2 includes a top 112A1-2 of the second battery cell 11-2, a first recess 112A21-2 of the second battery cell 11-2 located on the side of the first battery cell 11-1 (left side in Figure 7(A)) relative to the top 112A1-2 of the second battery cell 11-2, and a second recess 112A22-2 of the second battery cell 11-2 located on the opposite side of the first battery cell 11-1 (right side in Figure 7(A)) relative to the top 112A1-2 of the second battery cell 11-2. As shown in Figure 7(B), the first member 131 of the heat dissipation material 13 includes a first part 131-1 of the first member 131 abutting the top 112A1-1 of the first battery cell 11-1, and a second part 131-2 of the first member 131 abutting the top 112A1-2 of the second battery cell 11-2. The second member 132 of the heat dissipation material 13 includes a first portion 132-1 of the second member 132 that abuts against the first recess 112A21-1 (see FIG. 7(A)) of the first battery cell 11-1, a second portion 132-2 of the second member 132 that abuts against the second recess 112A22-1 (see FIG. 7(A)) of the first battery cell 11-1 and the first recess 112A21-2 (see FIG. 7(A)) of the second battery cell 11-2, and a third portion 132-3 of the second member 132 that abuts against the second recess 112A22-2 (see FIG. 7(A)) of the second battery cell 11-2. That is, in the example shown in FIGS. 6 and 7, the second portion 132-2 of the second member 132 of the heat dissipation material 13 is shared by the first battery cell 11-1 and the second battery cell 11-2.

[0034] In the comparative battery module using a sheet-type heat dissipation material, the heat dissipation material cannot absorb the dimensional tolerances of the battery cells. Also, because the compressive stress during assembly of the battery cells and the heat dissipation material is high, even if an attempt is made to compress the heat dissipation material by pressing the battery cells against it, the heat dissipation material cannot be compressed to the target thickness. On the other hand, in one example of the battery module M of the second embodiment, the heat dissipation material 13 is of a hardening type, so that the heat dissipation material 13 can be compressed by pressing the multiple battery cells 11 against the heat dissipation material 13, and the dimensional tolerance of the multiple battery cells 11 can be absorbed by the heat dissipation material 13.

[0035] [First Example] The results of the study on the external input of the first member 131 and the second member 132 of the heat dissipation material 13 are shown below. As the first member 131, a two-component curing urethane-based heat dissipation material manufactured by Dupont having the following characteristics was used. The thermal conductivity was 3.0 [W / mK], the hardness (Asker C: Asker hardness C type) was 87, the adhesive strength was 1.3 [MPa], and the elongation rate was 10 [%]. As the second member 132, a two-component curing silicone-based heat dissipation material manufactured by Wacker Asahi Kasei Silicone having the following characteristics was used. The thermal conductivity was 3.0 [W / mK], the hardness (Asker C: Asker hardness C type) was 10, the adhesive strength was 0.01 [MPa], and the elongation rate was 20 [%].

[0036] FIG. 8 is a diagram showing the relationship between the area ratio (ratio of adhesive area) of the first member 131 and the shear adhesive strength (shear adhesive strength [MPa]) of the first member 131. FIG. 9 is a diagram showing the relationship between the area ratio (ratio of adhesive area) of the second member 132 and the shear adhesive strength (shear adhesive strength [MPa]) of the second member 132. Since a lateral force is applied to the battery cell 11 during external input, the shear adhesive strength was confirmed by performing a tensile test (tensile shear adhesive strength test: JIS K 6850). In the tensile test, the dimensions of the first member 131 and the second member 132 were set to 25 mm × 12.5 mm × thickness 2.0 mm, and the tensile speed was set to 50 mm / min. As shown in FIG. 8, the shear adhesive strength required for suppressing the lateral positional displacement of the battery cell 11 by the first member 131 became 0.45 MPa or more, and the adhesive area of ​​the battery cell 11 with the bottom surface 112A of the exterior body 112 became 37% or more. As shown in FIG. 9, even if the adhesive area between the second member 132 and the bottom surface 112A of the exterior body 112 of the battery cell 11 is 100%, the shear adhesive strength is less than 0.45 MPa, and therefore it was found that the lateral displacement of the battery cell 11 cannot be suppressed by the second member 132 alone.

[0037] [Second Example] The results of an investigation into abnormal heat generation in the battery cells 11 of the first member 131 and the second member 132 of the heat dissipation material 13 are shown below. When the bottom surface 112A of the exterior body 112 of the battery cell 11 is deformed into a convex shape due to heat generation from the electrode body 111 of the battery cell 11, the concave portion 112A2 of the bottom surface 112A of the exterior body 112 of the battery cell 11 peels off from the first member 131, and the contact area between the bottom surface 112A of the exterior body 112 of the battery cell 11 and the first member 131 decreases to 30%. Therefore, it was found that if the heat dissipation material 13 were composed only of the first member 131, the necessary heat conductivity could not be ensured. Fig. 10 is a diagram showing the relationship between the contact area retention rate [%] between the bottom surface 112A of the exterior body 112 of the battery cell 11 and the first member 131 and the amount of heat transferred [W] to the cooler 12 via the first member 131. As shown in Fig. 13, when the bottom surface 112A of the exterior body 112 of the battery cell 11 is deformed into a convex shape (when the cell generates abnormal heat), it was found that the amount of heat transferred to the cooler 12 via the first member 131 needs to be 73 [W] or more, and therefore the contact area retention rate between the bottom surface 112A of the exterior body 112 of the battery cell 11 and the first member 131 needs to be 80 [%] or more. From the above results, it was found that when the thermal conductivity of the first member 131 and the thermal conductivity of the second member 132 are equal, in order to suppress lateral displacement of the battery cell 11 when an external input applies a lateral force to the battery cell 11 (heat dissipation structure 1), the proportion of the first member 131 in the heat dissipation material 13 needs to be 37% or more, and in order to ensure heat transfer to the cooler 12 via the heat dissipation material 13 when the bottom surface 112A of the outer casing 112 of the battery cell 11 is deformed into a convex shape (when the cell generates abnormal heat), the proportion of the second member 132 in the heat dissipation material 13 needs to be 50% (80% to 30%).

[0038] As described above, the heat dissipation structure and the battery module according to the present disclosure have been described with reference to the drawings, but the heat dissipation structure and the battery module according to the present disclosure are not limited to the above-described embodiments, and may be modified as appropriate without departing from the spirit and scope of the present disclosure. The configurations of the examples of the above-described embodiments may be combined as appropriate. [Explanation of symbols]

[0039] 1...heat dissipation structure, 11...battery cell, 11-1...first battery cell, 11-2...second battery cell, 111...electrode body, 112...exterior body, 112A...bottom surface, 112A-1...bottom surface, 112A-2...bottom surface, 112A1...top portion, 112A1-1...top portion, 112A1-2...top portion, 112A2...recess, 112A21-1...first recess, 112A22- 1...second recess, 112A21-2...first recess, 112A22-2...second recess, 12...cooler, 13...heat dissipation material, 131...first member, 131-1...first part, 131-2...second part, 132...second member, 132-1...first part, 132-2...second part, 132-3...third part, M...battery module, M1...end plate, M2...thermal insulation material

Claims

1. A battery cell having an electrode assembly and an exterior body that houses the electrode assembly; A cooler arranged to face a bottom surface of the exterior body; a heat dissipation material disposed between the bottom surface and the cooler and in contact with the bottom surface and the cooler; the bottom surface is deformed in a convex shape toward the cooler and the heat dissipation material by the heat generated by the electrode body, The heat dissipation material includes a first member having a first elongation rate and a second member having a second elongation rate higher than the first elongation rate, The first member is disposed at a position where it abuts at least on an apex of the bottom surface that is deformed into a convex shape, A heat dissipation structure, wherein the second member is positioned adjacent to the first member and in abutment against a recess, which is a portion of the bottom surface that deforms less toward the cooler than the top portion.

2. the hardness of the first member is higher than the hardness of the second member; The heat dissipation structure according to claim 1 , wherein an adhesive strength of the first member is greater than an adhesive strength of the second member.

3. A battery module having the heat dissipation structure according to claim 1, A plurality of the battery cells are arranged side by side, the top portion of each of the plurality of battery cells abuts against the first member; the recessed portion of each of the plurality of battery cells abuts against the second member.

4. The heat dissipation structure according to claim 1 , wherein a ratio of an area of ​​a contact surface between the first member and the cooler to an area of ​​a contact surface between the second member and the cooler is from 4 / 6 to 6 / 4.

5. The plurality of battery cells includes at least a first battery cell and a second battery cell arranged next to the first battery cell, a bottom surface of the first battery cell includes a top portion of the first battery cell, a first recess portion of the first battery cell located on the opposite side of the top portion of the first battery cell to the second battery cell, and a second recess portion of the first battery cell located on the side of the second battery cell to the top portion of the first battery cell, a bottom surface of the second battery cell includes a top portion of the second battery cell, a first recess portion of the second battery cell located closer to the first battery cell than the top portion of the second battery cell, and a second recess portion of the second battery cell located on the opposite side of the first battery cell than the top portion of the second battery cell, the first member includes at least a first portion of the first member that abuts against a top portion of the first battery cell and a second portion of the first member that abuts against a top portion of the second battery cell, 4. The battery module of claim 3, wherein the second member includes at least a first portion of the second member abutting against a first recess of the first battery cell, a second portion of the second member abutting against the second recess of the first battery cell and the first recess of the second battery cell, and a third portion of the second member abutting against the second recess of the second battery cell.

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