Battery pack manufacturing method

Abstract

To form a thermally conductive layer interposed between a first member and a second member to have an appropriate thickness and area.SOLUTION: A battery pack manufacturing method is a method for manufacturing a battery pack including a first member, a second member having a higher rigidity than the first member, and a thermally conductive layer provided between the first member and the second member. This manufacturing method includes a first application step, a second application step, and an assembly step. The first application step is a step of applying a first thermally conductive agent to the first member. The second application step is a step of applying a second thermally conductive agent having a higher elastic modulus than the first thermally conductive agent on the first thermally conductive agent applied in the first application step. The assembly step is a step of applying a load by the second member from above the second thermally conductive agent applied in the second application step, thereby forming a thermally conductive layer between the first member and the second member.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] Patent Document 1 discloses a battery pack. The battery pack includes a battery, a cooler, and a viscoelastic layer (thermal conduction layer). The viscoelastic layer is interposed between the heat dissipation surface of the battery and the cooling surface of the cooler, and transfers heat from the battery to the cooler. The battery pack also includes an expansion restriction portion that restricts the viscoelastic layer from expanding to reduce its thickness. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-009672 A Summary of the Invention [Problem to be solved by the invention]

[0004] A battery pack including a first member, a second member, and a thermally conductive layer provided between the first member and the second member has the following problem. That is, when a thermally conductive layer is formed by applying a thermally conductive agent to the first member (one member) and applying a load to the thermally conductive agent by the second member (the other member), if the rigidity of the first member is low, the first member itself will deform. As a result, it may be difficult to form a thermally conductive layer with an appropriate thickness and area.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a manufacturing method for a battery pack that enables a thermally conductive layer interposed between a first member and a second member to be formed so as to have an appropriate thickness and area. [Means for solving the problem]

[0006] The manufacturing method of a battery pack according to the present disclosure is a method for manufacturing a battery pack including a first member, a second member having a higher rigidity than the first member, and a thermally conductive layer provided between the first member and the second member. This manufacturing method includes a first application step, a second application step, and an assembly step. The first application step is a step of applying a first thermally conductive agent to the first member. The second application step is a step of applying a second thermally conductive agent having a higher elastic modulus than the first thermally conductive agent on the first thermally conductive agent applied in the first application step. The assembly step is a step of applying a load by the second member from above the second thermally conductive agent applied in the second application step, thereby forming a thermally conductive layer between the first member and the second member. Effect of the Invention

[0007] The manufacturing method of the battery pack according to the present disclosure makes it possible to form a thermally conductive layer having an appropriate thickness and area. [Brief description of the drawings]

[0008] [Figure 1] 1 is a perspective view showing an example of a main configuration of a battery pack manufactured by a manufacturing method according to an embodiment; [Diagram 2] 1A and 1B are diagrams for explaining problems that arise when forming a thermally conductive layer between a first member and a second member of a battery pack. [Diagram 3] 5A to 5C are diagrams for explaining a manufacturing method of a battery pack according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] 1. Battery pack configuration Fig. 1 is a perspective view showing an example of a main configuration of a battery pack 10 manufactured by a manufacturing method according to an embodiment. The battery pack 10 is mounted on an electric vehicle such as a battery electric vehicle (BEV). As shown in Fig. 1, the battery pack 10 includes a battery module 12, a case (housing) including a lower case 14, a cooler 16, and a thermally conductive layer 18.

[0010] 1, a battery pack 10 includes a plurality of battery modules 12. Each battery module 12 includes a plurality of stacked battery cells. A lower case 14 is formed to house the battery modules 12. The cooler 16 is, for example, a water-cooled type.

[0011] 1, the thermally conductive layer 18 is applied to an inner surface 14i (see FIG. 3) of the bottom wall of the lower case 14, and is formed so as to be interposed between the inner surface 14i and the bottom surface 12b of each battery module 12. The thermally conductive layer 18 is also applied to an outer surface 14o (see FIG. 3) of the bottom wall of the lower case 14, and is formed so as to be interposed between the outer surface 14o and an upper surface 16u of the cooler 16.

[0012] In the battery pack 10 shown in Fig. 1, the lower case 14 corresponds to an example of a "first member" according to the present disclosure. The battery module 12 and the cooler 16 each correspond to an example of a "second member" according to the present disclosure. The battery module 12 (second member) is formed to have higher rigidity than the lower case 14 (first member). The cooler 16 (second member) is also formed to have higher rigidity than the lower case 14 (first member).

[0013] 2. Battery pack manufacturing method FIG. 2 is a diagram (cross-sectional view) for explaining the problem when forming a thermally conductive layer between a first member and a second member of a battery pack. According to a general method for forming a thermally conductive layer, as shown in FIG. 2, first, a thermally conductive agent is applied onto a first member placed on a table (not shown). Next, a load is applied to the thermally conductive agent by pressing the second member against the first member. More specifically, the load is based on the weight of the second member and a force applied from the outside to the second member.

[0014] Regarding the formation of the thermally conductive layer, it is required to form the thermally conductive layer with an appropriate thickness and area by appropriately crushing the thermally conductive agent using the load from the second member. However, if the rigidity of the first member that receives the load is low, the first member itself will deform (bend) due to the reaction force of the thermally conductive agent pressing against it. As a result, it becomes difficult to properly transmit the load to the thermally conductive agent. In addition, due to the variation in the shapes of the first member and the second member, the space S (see Figure 2) for crushing the thermally conductive agent will vary. This variation in the space S can also be an obstacle to properly crushing the thermally conductive agent.

[0015] Fig. 3 is a diagram (cross-sectional view) for explaining a manufacturing method of a battery pack 10 according to an embodiment. In consideration of the above-mentioned problems, the manufacturing method according to the present embodiment includes a "first application step", a "second application step", and an "assembly step" as shown in Fig. 3. Note that, although Fig. 3 shows a battery module 12 as an example of the "second member", the manufacturing method shown in Fig. 3 can be similarly applied to an example in which a cooler 16 corresponds to the second member.

[0016] In this embodiment, two types of thermal conductive agents having different elastic moduli (N / mm), namely, first and second thermal conductive agents 20 and 22, are used to form the thermal conductive layer 18. The elastic modulus of the second thermal conductive agent 22 is higher than that of the first thermal conductive agent 20. That is, the first thermal conductive agent 20 is a liquid that is more easily crushed than the second thermal conductive agent 22. In other words, the second thermal conductive agent 22 is a liquid that is less easily crushed than the first thermal conductive agent 20. The difference in elastic modulus referred to here can be realized, for example, by selecting a material for the first thermal conductive agent 20 that has a lower content of reactant than the second thermal conductive agent 22. Alternatively, the difference can be realized, for example, by selecting a material for the first thermal conductive agent 20 that has a lower reaction force of the thermal conductive agent (for example, a material that includes a plasticizer or a material that has a higher content of plasticizer).

[0017] First, in the first application step, a first thermally conductive agent 20 having a low elastic modulus is applied to an inner surface 14i of a bottom wall of a lower case 14 (first member) having a low rigidity, as shown in Fig. 3. In an example in which the cooler 16 corresponds to the second member, the first thermally conductive agent 20 is applied to an outer surface 14o of the bottom wall.

[0018] The second application step is performed after the first application step. In the second application step, a second thermally conductive agent 22 having a high elastic modulus is applied onto the first thermally conductive agent 20 applied to the lower case 14 in the first application step.

[0019] The assembly process is performed after the second application process. In the assembly process, a load is applied from above the second thermally conductive agent 22 applied in the second application process to the second thermally conductive agent 22 and the first thermally conductive agent 20 by the battery module 12 (second member). This forms a thermally conductive layer 18 between the lower case 14 and the battery module 12. In addition, the thermally conductive layer 18 thus formed has a two-layer structure of a layer made of the first thermally conductive agent 20 and a layer made of the second thermally conductive agent 22, as shown in FIG. 3. The thermal resistances of these two layers are different from each other.

[0020] As described above, according to the manufacturing method of the battery pack 10 of the present embodiment, the first thermal conductive agent 20 having a low elastic modulus (i.e., easily crushed) is applied onto the first member (lower case 14) on the side of low rigidity. As a result, in comparison with a comparative example in which only the second thermal conductive agent 22 having a high elastic modulus is used, the first thermal conductive agent 20 is crushed while favorably following the deformation of the lower case 14 and the variation in the space S (see FIG. 2) caused by the pressing reaction force of the thermal conductive agents (the first thermal conductive agent 20 and the second thermal conductive agent 22) as shown in FIG. 3. Furthermore, the inclusion of the second thermal conductive agent 22 having a high elastic modulus makes it possible to appropriately secure the elastic modulus of the thermal conductive layer 18 as a whole. Therefore, according to this manufacturing method, it becomes possible to form the thermal conductive layer 18 so as to have an appropriate thickness and area.

[0021] In addition, according to the present manufacturing method, since the thermally conductive layer 18 can be formed to have an appropriate thickness and area as described above, it is possible to suppress a decrease in the thermal conductivity of the thermally conductive layer 18. Moreover, compared to the comparative example in which only the second thermally conductive agent 22 having a high elastic modulus is used, it is possible to suppress deformation of the lower case 14 (first member) itself. [Explanation of symbols]

[0022] 10 battery pack, 12 battery module, 14 lower case, 16 cooler, 18 thermally conductive layer, 20 first thermally conductive material, 22 second thermally conductive material

Claims

1. A method for manufacturing a battery pack including a first member, a second member having a higher rigidity than the first member, and a thermally conductive layer provided between the first member and the second member, comprising: a first application step of applying a first thermal conductive agent to the first member; a second coating step of coating a second thermal conductive agent having a higher elastic modulus than the first thermal conductive agent on the first thermal conductive agent coated in the first coating step; an assembly process in which a load is applied by the second member from above the second thermally conductive agent applied in the second application process, thereby forming the thermally conductive layer between the first member and the second member; A manufacturing method of a battery pack comprising:

2. The first member is a case of the battery pack. The method for manufacturing a battery pack according to claim 1 .

3. The second member is a battery module housed in the battery pack.

3. The method for manufacturing a battery pack according to claim 1 or 2.

4. The second member is a cooler that cools a battery module housed in the battery pack.

3. The method for manufacturing a battery pack according to claim 1 or 2.

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