Battery pack manufacturing method

Abstract

To reduce thermal damage to bipolar batteries caused by the heat generated by curable resin compositions. [Solution] The method for manufacturing a battery pack includes the following steps in this order: (a) stacking multiple bipolar batteries to form a battery stack. (b) placing the battery stack inside a housing. (c) filling the gap between the battery stack and the housing inside the housing with a first cured resin product. (d) injecting a liquid curable resin composition into at least a portion of the remaining gap. (e) curing the curable resin composition to form a second cured resin product.

Description

Technical Field

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

Background Art

[0002] JP-A-2008-166256 discloses a bipolar battery.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Large-sized battery packs are being considered. The battery pack includes a housing and a battery laminate. The housing houses the battery laminate. The battery laminate is formed by laminating a plurality of bipolar batteries. Each bipolar battery has a large area. In the housing, the gap between the battery laminate and the housing is filled with a potting material. Generally, the potting material is a curable resin composition. In a large-sized battery pack, the amount of the curable resin composition used also increases. The curable resin composition can generate heat during curing. When a large amount of the curable resin composition generates heat, the bipolar battery may be damaged by heat.

[0005] An object of the present disclosure is to reduce heat damage to the bipolar battery caused by heat generation of the curable resin composition.

Means for Solving the Problems

[0006] 1. The method for manufacturing a battery pack includes the following (a) to (e) in this order. (a) A battery laminate is formed by laminating a plurality of bipolar batteries. (b) The battery laminate is disposed in the housing. (c) Inside the housing, the first resin curing material is filled into the gap between the battery stack and the housing. (d) Inject a liquid curable resin composition into at least a portion of the remaining gap. (e) A second cured resin product is formed by curing the curable resin composition.

[0007] The potting material of this disclosure includes a first resin cured product and a second resin cured product. The first resin cured product is formed by pre-curing a curable resin composition. The formation of the first resin cured product can be carried out in advance, for example, outside the housing. After filling with the first resin cured product, the curable resin composition is injected to fill the remaining gaps. The second resin cured product is formed by the curing of the injected curable resin composition. Since the first resin cured product is pre-cured, the heat generated is only that of the second resin cured product. By reducing the heat generated, thermal damage to the bipolar cell can be reduced.

[0008] 2. The method for manufacturing the battery pack described in "1" above may include, for example, the following configuration: The first resin cured product is formed by heat curing of a curable resin composition.

[0009] Heat-curing resin cured products tend to have high material strength. On the other hand, they tend to generate a large amount of heat during curing. In this disclosure, since the first resin cured product is cured in advance, a heat-curing resin cured product can be formed without causing thermal damage to the bipolar battery.

[0010] 3. The method for manufacturing the battery pack described in "1" or "2" above may include, for example, the following configuration: The second resin cured product is formed by room temperature curing of the curable resin composition.

[0011] The fact that the second resin cured product is room-temperature curing type can further reduce the amount of heat generated.

[0012] 4. The method for manufacturing a battery pack described in any one of items "1" to "3" above may include, for example, the following configuration: The volume fraction of the first resin cured product to the total volume of the first resin cured product (heat curing type) and the second resin cured product (room temperature curing type) is 60% or more and 99% or less.

[0013] Heat-curing resins tend to generate a large amount of heat and have high material strength. Room-temperature curing resins tend to generate a small amount of heat and have low material strength. By having a relatively high volume fraction of the first resin cured product (heat-curing type), a potting material can be formed that combines the advantages of both heat-curing and room-temperature curing resins.

[0014] Hereinafter, one embodiment of the present disclosure (which may be abbreviated as "this embodiment") and one example of the present disclosure (which may be abbreviated as "this example") will be described. However, this embodiment and this example will not limit the technical scope of the present disclosure. This embodiment and this example are illustrative in all respects. This embodiment and this example are not restrictive. The technical scope of the present disclosure includes all modifications within the meaning and scope equivalent to the claims. For example, it is intended from the outset that any configuration may be extracted from this embodiment and combined in any way. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic flowchart of the manufacturing method of the battery pack in this embodiment. [Figure 2] This is a first schematic diagram showing the manufacturing process of the battery pack in this embodiment. [Figure 3] This is a schematic cross-sectional view of a bipolar battery. [Figure 4] This is a second schematic diagram showing the manufacturing process of the battery pack in this embodiment. [Figure 5] This is a third schematic diagram showing the manufacturing process of the battery pack in this embodiment. [Figure 6] This is a fourth schematic diagram showing the manufacturing process of the battery pack in this embodiment. [Figure 7]It is a graph showing the results of the compression test.

Mode for Carrying Out the Invention

[0016] Method for manufacturing a battery pack FIG. 1 is a schematic flowchart of the method for manufacturing a battery pack in the present embodiment. Hereinafter, the method for manufacturing a battery pack in the present embodiment may be abbreviated as "this method". This method includes, in this order, "(a) formation of a laminate", "(b) exterior", "(c) filling of a first resin cured product", "(d) injection of a curable resin composition", and "(e) curing".

[0017] (a) Formation of a laminate FIG. 2 is a first schematic diagram showing the manufacturing process of a battery pack in the present embodiment. This method includes forming a battery laminate 15 by laminating a plurality of bipolar batteries 10. Each of the plurality of bipolar batteries 10 may have, for example, a plate-like outer shape. The bipolar battery 10 may have a large area. The bipolar battery 10 may have a planar size of, for example, 1000 mm to 2000 mm × 1000 mm to 2000 mm. The bipolar batteries 10 may be joined to each other by, for example, an adhesive. The battery laminate 15 may further include, for example, a current collector plate, a cooler, etc. in addition to the bipolar batteries 10. The current collector plate and the cooler may be disposed between the bipolar batteries 10.

[0018] FIG. 3 is a schematic cross-sectional view of a bipolar battery. The bipolar battery 10 may be, for example, a lithium-ion battery. The bipolar battery 10 includes an electrode laminate 5. The electrode laminate 5 is formed by laminating bipolar electrodes 1. A separator 2 is disposed between the bipolar electrodes 1. A current collector plate 6 is disposed at an end in the stacking direction (Z direction). In the plane direction (Z direction), each of the plurality of bipolar electrodes 1 includes a positive electrode layer 1a, a current collector 1c, and a negative electrode layer 1b in this order. The positive electrode layer 1a contains a positive electrode active material. The negative electrode layer 1b contains a negative electrode active material. The positive electrode layer 1a and the negative electrode layer 1b are in a front-back positional relationship.

[0019] The current collector 1c may be formed, for example, by bonding together an Al foil and a Cu foil. The current collector 1c extends outward in the in-plane direction (XY direction) beyond the positive electrode layer 1a and the negative electrode layer 1b. The sealing material 3 may include a first sealing material 3a and a second sealing material 3b. The first sealing material 3a seals the gaps between adjacent current collectors 1c, thereby partitioning the cells 4. A cell 4 is the smallest unit of a battery. Electrolyte can be injected into each of the multiple cells 4. Since the bipolar battery 10 includes multiple cells 4, it may also be called a "bipolar module". The second sealing material 3b can seal the gap between the first sealing material 3a and the outer casing 9. The outer casing 9 may include, for example, an aluminum laminate film.

[0020] (b) Exterior As shown in Figure 2, the method includes placing the battery stack 15 inside the housing 20. The housing 20 may be, for example, a container made of resin or metal. The housing 20 may be composed of, for example, multiple parts. The housing 20 may include, for example, an upper case and a lower case.

[0021] (c) Filling of the first resin curing product Figure 4 is a second schematic diagram showing the manufacturing process of the battery pack in this embodiment. This method includes filling the gap between the battery stack 15 and the housing 20 with the first cured resin 31 inside the housing 20.

[0022] Prior to filling, a first cured resin product 31 is prepared. The first cured resin product 31 may have any form. For example, the first cured resin product 31 may be bead-shaped. The beads may be spherical, for example. It is thought that the spherical shape of the beads facilitates close packing. The beads may be molded to be smaller than the gaps to which they are to be filled, for example. The beads may be of a size such that they do not become liquid-repellent to the liquid curable resin composition 35 that is subsequently injected.

[0023] The first cured resin product 31 may, for example, contain a thermosetting resin. The first cured resin product 31 may, for example, be a cured product of a liquid curable resin composition. The first cured resin product 31 may, for example, be a cured product of a two-component epoxy resin. The first cured resin product 31 may, for example, be a heat-curing type. The curing temperature may be, for example, 70°C to 150°C.

[0024] (d) Injection of curable resin composition Figure 5 is a third schematic diagram showing the manufacturing process of the battery pack in this embodiment. This method includes injecting a liquid curable resin composition 35 into at least a portion of the remaining gap filled with the first cured resin 31. The liquid curable resin composition 35 may be, for example, a two-component epoxy resin. The liquid curable resin composition 35 may be filled into a portion of the remaining gap. The liquid curable resin composition 35 may be filled into the entire remaining gap.

[0025] The curable resin composition 35 may be liquid and may not contain fillers. A liquid curable resin composition 35 may have low viscosity. A low-viscosity curable resin composition 35 is expected to penetrate even fine gaps easily.

[0026] (e) Hardening Figure 6 is a fourth schematic diagram showing the manufacturing process of the battery pack in this embodiment. This method includes forming a second cured resin product 32 by curing a curable resin composition 35. The battery pack 100 can be manufactured by forming the second cured resin product 32.

[0027] For example, the curable resin composition may be cured at room temperature. That is, the second cured resin product 32 may be a room-temperature curing type. The curing temperature may be, for example, 15°C to 35°C.

[0028] The first resin cured product 31 and the second resin cured product 32 form a potting material 30. In the potting material 30, the volume fraction of the first resin cured product 31 relative to the total volume of the first resin cured product 31 and the second resin cured product 32 may be, for example, 60% or more and 99% or less. This volume fraction may also be, for example, 70% or more, 80% or more, or 90% or more. The volume fraction of each resin cured product is determined from the cross-sectional area of ​​each resin cured product in the cross-section of the potting material 30. The higher the volume fraction of the second resin cured product 32 (heat-curing type), the greater the expected improvement in material strength.

[0029] The second resin cured product 32 may also contain a thermosetting resin, similar to the first resin cured product 31. The first resin cured product 31 and the second resin cured product 32 may each independently contain at least one selected from the group consisting of, for example, epoxy resin, urethane resin, and silicone resin. For example, both the first resin cured product 31 and the second resin cured product 32 may be epoxy resins. The first resin cured product 31 may contain a heat-curing epoxy resin. The second resin cured product 32 may contain a room-temperature curing epoxy resin.

[0030] Note (Manufacturing method for bipolar batteries) Furthermore, this method can also be applied to the manufacturing method of the bipolar battery 10. For example, in Figure 3, the first cured resin 31 and the second cured resin 32 may be applied to at least one of the first encapsulant 3a and the second encapsulant 3b.

[0031] In other words, the method for manufacturing the bipolar battery 10 may include, for example, the following (a) to (e). (a) An electrode stack 5 is formed by stacking multiple bipolar electrodes 1. (b) The electrode stack 5 is covered with an outer casing 9. (c) The gap between the electrode laminate 5 and the outer casing 9 is filled with the first cured resin 31. (d) Inject the liquid curable resin composition 35 into at least a portion of the remaining gap. (e) The curable resin composition 35 is cured to form a second cured resin product 32.

[0032] In the manufacturing method of the bipolar battery 10, it is expected that thermal damage to components such as the bipolar electrode 1, separator 2, and electrolyte will be reduced. [Examples]

[0033] Sample No. 1 (with resin beads) Resin beads were formed by molding a two-part epoxy resin into bead shapes at room temperature. The resin beads were annealed (heat-cured) in a 120°C oven for 3 hours to form a first cured resin product. The first cured resin product (resin beads) was filled into a cubic mold. Furthermore, two-part epoxy resin was injected into the remaining space in the mold. A second cured resin product was formed by curing the two-part epoxy resin at room temperature. Sample No. 1, a cubic sample, was prepared by demolding the cured resin product. The sample size was 12mm x 12mm x 12mm. Sample No. 1 contained both the first cured resin product (resin beads) and the second cured resin product.

[0034] Sample No. 2 (without resin beads) A two-part epoxy resin was poured into a cubic mold. At room temperature, the two-part epoxy resin cured, forming a cured resin product. By demolding the cured resin product, a cubic sample No. 2 was prepared. The sample size was 12mm x 12mm x 12mm. Sample No. 2 consisted of the second cured resin product (room temperature type).

[0035] Evaluation of material strength The compressive strength was measured by compressing the sample between two parallel compression plates. The test conditions were as follows: Testing equipment: High-precision universal testing machine "AGX-50kN" manufactured by Shimadzu Corporation. Measurement item: Compressive strength [N] Test speed: 5 mm / min Stroke length: 5mm

[0036] Figure 7 is a graph showing the results of the compression test. It was confirmed that sample No. 1 (with resin beads) had a higher compressive strength than sample No. 2 (without resin beads). [Explanation of Symbols]

[0037] 1 Bipolar electrode, 1a Positive electrode layer, 1b Negative electrode layer, 1c Current collector, 2 Separator, 3 Encapsulating material, 3a First encapsulating material, 3b Second encapsulating material, 4 Cell, 5 Electrode laminate, 6 Current collector plate, 9 Outer casing, 10 Bipolar battery, 15 Battery laminate, 20 Housing, 30 Potting material, 31 First cured resin, 32 Second cured resin, 35 Curable resin composition, 100 Battery pack.

Claims

[Claim 1] (a) Forming a battery stack by stacking multiple bipolar batteries, (b) Placing the battery stack inside the housing, (c) Fill the gap between the battery stack and the housing within the housing with the first cured resin, (d) Injecting a liquid curable resin composition into at least a portion of the remaining gap, (e) Forming a second cured resin product by curing the curable resin composition. It includes in this order, A method for manufacturing battery packs.

Images