Energy storage module and method for manufacturing an energy storage module

Abstract

To provide an energy storage module and a method for manufacturing the energy storage module that can improve the strength of the exterior body without managing gaps using spacers. [Solution] The energy storage module comprises a power generation element and an outer casing that covers the power generation element, the outer casing having a first outer casing that covers the surface of the power generation element and a second outer casing that covers the corners of the power generation element, and the first outer casing and the second outer casing are welded together so as to overlap at the positions where the corners of the power generation element are located.

Description

Technical Field

[0001] The present disclosure relates to a power storage module and a method for manufacturing the power storage module.

Background Art

[0002] Patent Document 1 discloses a power storage module in which a spacer is disposed inside a corner of a recess of an exterior body in order to suppress damage to the exterior body covering a power generation element.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a spacer is disposed inside an exterior body as in the power storage module disclosed in Patent Document 1, there is a problem that the volume energy density decreases.

[0005] The present disclosure has been made in view of the above, and an object thereof is to provide a power storage module and a method for manufacturing the power storage module that can improve the strength of an exterior body without performing gap management by a spacer.

Means for Solving the Problems

[0006] The power storage module according to the present disclosure includes a power generation element and an exterior body covering the power generation element, the exterior body having a first exterior portion covering a surface of the power generation element and a second exterior portion covering a corner portion of the power generation element, and the first exterior portion and the second exterior portion being welded so as to overlap at a position where the corner portion of the power generation element is disposed.

[0007] The method for manufacturing an energy storage module according to this disclosure includes a step of welding a first outer casing that covers the surface of a power generation element and a second outer casing that covers the corners of the power generation element so that they overlap at the positions where the corners of the power generation element are located. [Effects of the Invention]

[0008] According to this disclosure, by welding a multi-layered structure to the corners of the power generation element, the strength of the exterior can be improved without managing gaps with spacers. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a side view of the energy storage module according to this embodiment, viewed from the side. [Figure 2] Figure 2 is a top view of the energy storage module according to this embodiment. [Figure 3] Figure 3 is a diagram illustrating the first step of the manufacturing method for an energy storage module according to an embodiment. [Figure 4] Figure 4 is a diagram illustrating the second step of the manufacturing method for the energy storage module according to the embodiment. [Figure 5] Figure 5 is a diagram illustrating the third step in the manufacturing method of the energy storage module according to the embodiment. [Figure 6] Figure 6 is a diagram illustrating the fourth step in the manufacturing method of the energy storage module according to the embodiment. [Figure 7] Figure 7 is a diagram illustrating the fifth step in the manufacturing method of the energy storage module according to the embodiment. [Figure 8] Figure 8 is a diagram illustrating a modified example of the first step in the manufacturing method of the energy storage module according to the embodiment. [Modes for carrying out the invention]

[0010] A battery storage module and a method for manufacturing the battery storage module according to the embodiments of this disclosure will be described with reference to the drawings. Note that the components in the following embodiments include those that are easily substituted or substantially identical to those that are easily substituted by those skilled in the art.

[0011] (Energy storage module) The configuration of the energy storage module according to this embodiment will be described with reference to Figures 1 and 2. The energy storage module according to this embodiment is used as a battery for, for example, a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), or a battery electric vehicle (BEV). Specifically, the energy storage module according to this embodiment is a bipolar lithium-ion secondary battery.

[0012] Figure 1 is a side view of the energy storage module 1 according to an embodiment. Figure 2 is a top view of the energy storage module 1. The energy storage module 1 comprises an outer casing 11 and a power generation element 12.

[0013] The outer casing 11 is for covering the power generation element 12. The outer casing 11 houses the power generation element 12, for example, together with the electrolyte. As shown in Figure 2, the outer casing 11 is composed of a first outer casing 1111, a second outer casing 112, and a folded portion 113.

[0014] The first outer casing 111 is a current collector foil for supplying current from the power generation element 12. The outer casing 11 is a sheet-like conductive material, and is composed of metal foil such as aluminum, stainless steel, iron, copper, titanium, or nickel.

[0015] As shown in FIG. 1, the first exterior part 111 covers the surfaces (upper surface and lower surface) of the power generation element 12. That is, the first exterior part 111 is provided on the upper side and the lower side of the power storage module 1, respectively. Further, as shown in FIG. 2, the first exterior part 111 is formed in a rectangular shape as a whole. Also, the first exterior part 111 is welded to the second exterior part 112 at the position of the outer edge part. The position of the outer edge part of the first exterior part 111 is, in other words, the position where the corner parts of the power generation element 12 are arranged.

[0016] The second exterior part 112 is composed of a laminate film. The laminate film constituting the second exterior part 112 has a structure in which a plurality of materials are laminated. The laminate film is composed of, for example, a first resin layer made of a nylon resin (polyamide resin), an adhesive layer, a metal layer made of aluminum foil, and a second resin layer made of PE (polyethylene) or PP (polypropylene). The first resin layer and the second resin layer are composed of the above-mentioned thermoplastic resin (heat-weldable resin).

[0017] As shown in part A of FIG. 2, the second exterior part 112 covers the corner parts (the entire circumference of the corner parts) of the power generation element 12. Also, like the first exterior part 111, the second exterior part 112 is provided on the upper side and the lower side of the power storage module 1, respectively. Further, as shown in FIG. 2, the second exterior part 112 is formed in a frame shape (square frame shape) as a whole. Also, the second exterior part 112 is welded to the first exterior part 111 at the position of the inner edge part. The position of the inner edge part of the second exterior part 112 is, in other words, the position where the corner parts of the power generation element 12 are arranged. Also, the outer edge parts of the pair of second exterior parts 112 arranged above and below the power generation element 12 are welded to each other.

[0018] The folded-back portion 113 is provided at the corner position of the inner edge portion of the second exterior portion 112. This folded-back portion 113 is a portion where the laminate film constituting the second exterior portion 112 is folded back, and is a portion responsible for reinforcing the corner portion of the power generation element 12. In FIG. 2, an example is shown where folded-back portions 113 are provided at the four corner positions of the inner edge portion of the second exterior portion 112, but the folded-back portion 113 may be provided at at least one of the four corner positions of the inner edge portion of the second exterior portion 112.

[0019] The power generation element 12 is a current collector for bipolar electrodes. This current collector is composed of a first metal foil and a second metal foil adhered via a conductive adhesive layer, and a negative electrode active material layer and a positive electrode active material layer applied to the first metal foil and the second metal foil, respectively.

[0020] The first metal foil and the second metal foil are composed of, for example, copper foil, copper alloy foil, nickel foil, aluminum foil, aluminum alloy foil, stainless steel foil, carbon sheet, etc. The first metal foil is, for example, copper foil, and the negative electrode active material layer is applied. Also, the second metal foil is, for example, aluminum foil, and the positive electrode active material layer is applied.

[0021] (Method for manufacturing a power storage module) Regarding the process flow of the method for manufacturing the power storage module according to the embodiment, it will be described while referring to FIGS. 3 to 8. In the method for manufacturing the power storage module 1, a first step, a second step, a third step, a fourth step, and a fifth step are performed.

[0022] <First step> In the first step, as shown in FIG. 3, a laminate film 13 cut to a predetermined size is prepared. The laminate film 13 is formed in a rectangular shape.

[0023] <Second step> In the second step, as shown in Figure 4, the central part of the laminate film 13 is punched out in a predetermined shape. After punching out, four protrusions 114 are formed on the laminate film 13. These protrusions 114 are located at the corners (inner corners) of the inner edge of the laminate film 13 that has been punched out in a frame shape.

[0024] <Third step> In the third step, as shown in Figure 5, the four protrusions 114 are folded back and welded. This creates the second exterior part 112 with the folded-back portion 113. The protrusions 114 can be welded using, for example, a heat bar or an impulse sealer.

[0025] <Fourth process> In the fourth step, as shown in Figure 6, the first outer casing 111 for covering the surface of the power generation element 12 and the second outer casing 112 for covering the corners of the power generation element 12 are welded together so that they overlap at the positions where the corners of the power generation element 12 are located. In this case, the first outer casing 111 is positioned on the far side of the second outer casing 112 in the paper, and the outer edge of the first outer casing 111 and the inner edge of the second outer casing 112 overlap. The welding of the first outer casing 111 and the second outer casing 112 can be performed using, for example, a heat bar or an impulse sealer.

[0026] <Fifth process> In the fifth step, the outer casing 11, consisting of the first outer casing 111 and the second outer casing 112, is placed above and below the power generation element 12, and embossing (convex molding) is performed using a press mold as shown in Figure 7. The energy storage module 1 is manufactured by following these steps.

[0027] In the first step described in Figure 3, a rectangular laminate film 13 was prepared. However, as shown in Figure 8, for example, a laminate film 13A made by combining multiple segment-shaped laminate films may also be prepared. This laminate film 13A is formed in a frame shape as a whole.

[0028] By using the pre-formed frame-shaped laminate film 13A in this way, the amount of laminate film to be punched out in the second step can be reduced, thereby improving the yield when manufacturing the energy storage module 1. In the second step using the laminate film 13A, for example, a protrusion 114 is formed at the position of part B in Figure 8.

[0029] According to the energy storage module 1 and the manufacturing method for the energy storage module 1 described above, the strength of the outer casing 11 can be improved without managing gaps with spacers by welding the outer casing 11 in a multi-layer structure at the corners of the power generation element 12. Furthermore, since no spacers are used in the energy storage module 1 and the manufacturing method for the energy storage module 1, the volumetric energy density does not decrease.

[0030] Furthermore, to improve the reliability of the storage module's casing, it is necessary to control the gap between the embossed corners of the casing and the corners of the power generation elements to be below a certain level. For example, if the gap exceeds a certain level during depressurization, wrinkles will form, and repeated expansion and contraction can cause stress to concentrate, potentially leading to fracture.

[0031] On the other hand, in the energy storage module 1 and the method for manufacturing the energy storage module 1, the strength of the outer casing 11 can be improved by folding the laminate film that constitutes the outer casing 11 and welding it to form a multilayer structure. Furthermore, there is no need to manage the gap between the corners of the outer casing 11 and the corners of the power generation element 12. In addition, in the energy storage module 1 and the method for manufacturing the energy storage module 1, by folding from the first outer casing 111 side, it is possible to improve the strength of the corners while suppressing a deterioration in yield.

[0032] Further effects and modifications can be readily derived by those skilled in the art. Therefore, broader aspects of the present invention are not limited to the specific details and representative embodiments expressed and described above. Accordingly, various modifications are possible without departing from the spirit or scope of the overall concept of the invention as defined by the appended claims and their equivalents. [Explanation of symbols]

[0033] 1. Energy storage module 11 Exterior 111 First exterior part 112 Second exterior part 113 Folded section 114 Protrusion 12 Power generation elements 13,13A Laminating Film

Claims

1. Power generation elements, The outer casing covering the power generation element, Equipped with, The exterior body is, A first outer casing covering the surface of the power generation element, A second outer casing covering the corner of the aforementioned power generation element, It has, The first outer casing and the second outer casing are welded together so as to overlap at the position where the corner of the power generation element is located. Energy storage module.

2. A method for manufacturing an energy storage module, comprising the step of welding a first outer casing that covers the surface of a power generation element and a second outer casing that covers the corners of the power generation element so that they overlap at the positions where the corners of the power generation element are located.

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