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 thinning due to expansion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-009672 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 and second members has the following problem: When a thermally conductive layer is formed by applying a thermally conductive agent to the first member (one of the members) and applying a load to the thermally conductive agent using 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 method for manufacturing a battery pack that enables a thermally conductive layer interposed between a first member and a second member to be formed to have an appropriate thickness and area. [Means for solving the problem]

[0006] A battery pack manufacturing method according to the present disclosure is a method for manufacturing a battery pack including a first member, a second member having higher rigidity than the first member, and a thermally conductive layer provided between the first member and the second member. The 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. [Effects of the Invention]

[0007] The manufacturing method of the battery pack according to the present disclosure makes it possible to form the thermally conductive layer so as to have an appropriate thickness and area. [Brief explanation 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; [Figure 2] 10A and 10B are diagrams for explaining problems that arise when a thermally conductive layer is formed between a first member and a second member of a battery pack. [Figure 3] 5A to 5C are diagrams for explaining a manufacturing method of a battery pack according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] 1. Battery pack configuration 1 is a perspective view schematically illustrating an example of the configuration of a main part 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] In the example shown in Fig. 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. A cooler 16 is, for example, a water-cooled type.

[0011] 1, the thermally conductive layer 18 is applied to the 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 the 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 the 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 issues involved in forming a thermally conductive layer between a first member and a second member of a battery pack. According to a typical method for forming a thermally conductive layer, as shown in FIG. 2, a thermally conductive agent is first applied to 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 externally applied to the second member.

[0014] To form a thermally conductive layer, it is necessary to use the load from the second component to appropriately compress the thermally conductive agent, resulting in a thermally conductive layer with the appropriate thickness and area. However, if the rigidity of the first component, which receives the load, is low, deformation (bending) occurs in the first component itself due to the reaction force from the thermally conductive agent. As a result, it becomes difficult for the load to be properly transmitted to the thermally conductive agent. Furthermore, variations in the shapes of the first component and the second component result in variations in the space S (see Figure 2) for compressing the thermally conductive agent. These variations in the space S can also hinder proper compression of the thermally conductive agent.

[0015] 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 this embodiment includes a "first application step," a "second application step," and an "assembly step," as shown in FIG. 3. Note that while FIG. 3 shows a battery module 12 as an example of the "second member," the manufacturing method shown in FIG. 3 can also be applied to an example in which a cooler 16 corresponds to the second member.

[0016] In this embodiment, two types of thermally conductive agents, namely, first and second thermally conductive agents 20 and 22, which have different elastic moduli (N / mm), are used to form the thermally conductive layer 18. The elastic moduli of the second thermally conductive agent 22 are higher than that of the first thermally conductive agent 20. That is, the first thermally conductive agent 20 is a liquid that is more easily crushed than the second thermally conductive agent 22. In other words, the second thermally conductive agent 22 is a liquid that is less easily crushed than the first thermally conductive agent 20. This difference in elastic moduli can be achieved, for example, by selecting a material for the first thermally conductive agent 20 that has a lower content of reactant than the second thermally conductive agent 22. Alternatively, this difference can be achieved, for example, by selecting a material for the first thermally conductive agent 20 that has a reduced reaction force of the thermally conductive agent (for example, a material that includes a plasticizer or a material with 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 consisting 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 this embodiment, the first thermally conductive agent 20, which has a low elastic modulus (i.e., is easily crushed), is applied to the first member (lower case 14) on the less rigid side. As a result, compared to a comparative example in which only the second thermally conductive agent 22, which has a high elastic modulus, the first thermally conductive agent 20 can better follow and crush in response to deformation of the lower case 14 and variations in the space S (see FIG. 2 ) caused by the pressing reaction force of the thermally conductive agents (first thermally conductive agent 20 and second thermally conductive agent 22), as shown in FIG. 3 . Furthermore, the inclusion of the second thermally conductive agent 22, which has a high elastic modulus, ensures that the overall elastic modulus of the thermally conductive layer 18 is appropriately maintained. Therefore, according to this manufacturing method, the thermally conductive layer 18 can be formed to have an appropriate thickness and area.

[0021] In addition, according to the present manufacturing method, it is possible to form the thermally conductive layer 18 to have an appropriate thickness and area as described above, thereby suppressing a decrease in the thermal conductivity of the thermally conductive layer 18. Furthermore, compared to a comparative example in which only the second thermally conductive agent 22 with a high elastic modulus is used, deformation of the lower case 14 (first member) itself can also be suppressed. [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 higher rigidity than the first member, and a thermally conductive layer provided between the first member and the second member, comprising: a first applying step of applying a first thermal conductive agent to the first member; a second application step of applying a second thermal conductive agent having a higher elastic modulus than the first thermal conductive agent on the first thermal conductive agent applied in the first application 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 the battery modules housed in the battery pack.

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

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