Energy storage module

Abstract

To provide an energy storage module that can improve the reliability of the energy storage module while suppressing the decrease in volumetric energy density. [Solution] The energy storage module comprises a power generation element and an outer casing covering the power generation element, the outer casing having a first outer casing that covers the surface and corners of the power generation element, a folded portion that is continuous with the first outer casing and protrudes from the side of the power generation element and is folded back to the side of the power generation element, and a second outer casing that is continuous with the folded portion and covers the corners of the first outer casing.

Description

Technical Field

[0001] The present disclosure relates to a power storage module.

Background Art

[0002] Patent Document 1 discloses a power storage module in which a spacer is disposed inside a recessed portion 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 in 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 capable of improving the reliability of the power storage module while suppressing a decrease in the volume energy density.

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 and a corner portion of the power generation element, a folded-back portion continuously extending from the first exterior portion, protruding from a side surface of the power generation element, and being folded back onto the side surface of the power generation element, and a second exterior portion continuously extending from the folded-back portion and covering a corner portion of the first exterior portion.

Effects of the Invention

[0007] According to this disclosure, by folding the outer casing to increase the strength of the corners, it is possible to improve the reliability of the energy storage module while suppressing a decrease in volumetric energy density. [Brief explanation of the drawing]

[0008] [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 cross-sectional view showing the energy storage module shown in Figure 2, cut at the position of line AA. [Figure 4] Figure 4 is a side view of a modified example 1 of the energy storage module according to the embodiment, viewed from the side. [Figure 5] Figure 5 is a top view of a modified example 1 of the energy storage module according to the embodiment. [Figure 6] Figure 6 is a cross-sectional view showing a modified example 2 of the energy storage module according to the embodiment. [Modes for carrying out the invention]

[0009] A battery storage module according to an embodiment 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 a person skilled in the art.

[0010] The configuration of the energy storage module according to this embodiment will be described with reference to Figures 1 to 3. The energy storage module according to this embodiment can be 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).

[0011] The energy storage module according to this embodiment is specifically a monopolar or bipolar lithium-ion secondary battery. In the following description, it is assumed that the energy storage module according to this embodiment is a monopolar lithium-ion secondary battery.

[0012] Figure 1 is a side view of the energy storage module 1 according to the embodiment. Figure 2 is a top view of the energy storage module 1. Figure 3 is a cross-sectional view showing the energy storage module 1 shown in Figure 2 cut at the position of line AA. The energy storage module 1 comprises an outer casing 11, a power generation element 12, a positive electrode tab lead 13, and a negative electrode tab lead 14.

[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 two laminate films that cover the upper side and the lower side of the power generation element 12, respectively.

[0014] The laminate film constituting the exterior body 11 has a structure in which multiple materials are laminated. The laminate film is composed of, for example, a first resin layer made of 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 and second resin layers are made of thermoplastic resins (heat-weldable resins) as described above.

[0015] Specifically, as shown in Figure 3, the outer casing 11 is composed of a first outer casing 111, a folded portion 112, and a second outer casing 113.

[0016] The first outer casing 111 covers the surface (top and bottom) of the power generation element 12. Furthermore, as shown in section B of Figure 3, the first outer casing 111 covers the corners of the power generation element 12.

[0017] The folded-back part 112 is continuous with the first exterior part 111. Also, the folded-back part 112 protrudes outward from the side surface of the power generation element 12 and is folded back to the side surface of the power generation element 12. Further, as shown in FIG. 2, the folded-back part 112 is provided on two sides, left and right in the drawing plane, among the four sides of the rectangular exterior body 11.

[0018] The second exterior part 113 is continuous with the folded-back part 112. Also, as shown in part B of FIG. 3, the second exterior part 113 is outside the first exterior part 111 and covers the corner part of the first exterior part 111.

[0019] Thus, in the power storage module 1, both ends of the laminate film constituting the exterior body 11 are folded back, and both ends of the folded-back laminate film are respectively positioned on the upper surface and the lower surface of the power generation element 12. Also, in the power storage module 1, the first exterior part 111 and the second exterior part 113 doubly cover the corner part of the power generation element 12.

[0020] Also, in the power storage module 1, the first exterior part 111 and the second exterior part 113 are welded. Also, in the power storage module 1, the folded-back part 112 continuous from the upper first exterior part 111 and the folded-back part 112 continuous from the lower first exterior part 111 are welded.

[0021] Also, the exterior body 11 is manufactured, for example, by the following procedure. (1) Fold the laminate film as shown in FIG. 3. (2) Using a heat bar, an impulse sealer, etc., weld the first exterior part 111 and the second exterior part 113 and also weld the upper and lower folded-back parts 112. (3) Perform embossing (convex molding) using a press mold.

[0022] The power generation element 12 is composed of a laminated electrode in which multiple positive electrode plates and multiple negative electrode plates are stacked with separators in between. Each positive electrode plate constituting the power generation element 12 is connected to a positive electrode tab lead 13. Each negative electrode plate constituting the power generation element 12 is connected to a negative electrode tab lead 14.

[0023] The positive electrode tab lead 13 is connected to each positive electrode plate constituting the power generation element 12 and is led out to the outside of the casing 11. The negative electrode tab lead 14 is connected to each negative electrode plate constituting the power generation element 12 and is led out to the outside of the casing 11.

[0024] With the energy storage module 1 having the above configuration, the reliability of the energy storage module 1 can be improved while suppressing a decrease in volumetric energy density by folding the outer casing 11 to increase the strength of the corners. In other words, the energy storage module 1 has a structure in which the multilayer structure part, which is made by folding and welding the laminate film that makes up the outer casing 11, is located at the corner of the embossed laminate film. This increases the strength of the corners and improves the reliability of the energy storage module 1 without the need for spacers as in the conventional method.

[0025] Furthermore, with the energy storage module 1, the strength of the outer casing 11 can be increased by welding the first outer casing 111 of the first layer and the second outer casing 113 of the second layer. In particular, by reinforcing areas where stress concentrates due to heat and cold (corners), it becomes possible to take measures against cracks and other problems.

[0026] Furthermore, as in the energy storage module 1, even without doubling the laminate film that makes up the outer casing 11, it is possible to suppress damage to the corners by increasing the thickness of the metal layer (aluminum foil) of the laminate film. However, producing laminate film of a certain thickness or more significantly reduces productivity. Therefore, in the energy storage module 1, in order to increase the rigidity of the laminate film without reducing productivity, it is folded and made into a multi-layer structure.

[0027] (Variation 1) A modified example of the energy storage module according to the embodiment will be described with reference to Figures 4 and 5. In the energy storage module 1 described above, folded portions 112 were provided on two of the four sides of the outer casing 11, on the left and right sides of the paper (see Figure 2), but the position of the folded portions 112 is not limited to this.

[0028] The outer casing 11A of the energy storage module 1A shown in Figures 4 and 5 consists of a first outer casing 111A, a folded portion 112A, and a second outer casing 113A. Furthermore, the state of the energy storage module 1A shown in Figure 5, when cut at the CC line, is the same as in Figure 3.

[0029] The first outer casing 111A covers the surface (top and bottom) and corners of the power generation element 12. The folded portion 112A is continuous with the first outer casing 111A.

[0030] The folded portion 112A protrudes outward from the side surface of the power generation element 12 and is folded back to the side surface of the power generation element 12. Furthermore, as shown in Figure 5, the folded portion 112A is provided on two of the four sides of the rectangular outer casing 11A, specifically the top and bottom sides in the plane of the paper.

[0031] The second outer section 113A is continuous with the folded-over section 112A. Furthermore, the second outer section 113A is on the outside of the first outer section 111A and covers the corner of the first outer section 111A.

[0032] With the energy storage module 1A having the above configuration, the reliability of the energy storage module 1A can be improved while suppressing a decrease in volumetric energy density by folding the outer casing 11A to increase the strength of the corners. In other words, in the energy storage module 1A, the multilayer structure formed by folding and welding the laminate film constituting the outer casing 11A is located at the corners of the embossed laminate film. This increases the strength of the corners, and the reliability of the energy storage module 1A can be improved without the need for spacers as in the conventional method.

[0033] (Modification 2) A modified example 2 of the energy storage module according to the embodiment will be described with reference to Figure 6. In the energy storage module 1 described above, a spacer 15 may be provided inside the outer casing 11 as needed, for example, as shown in Figure 6.

[0034] The spacer 15 is made of, for example, synthetic resin and is provided at the inner end of the outer casing 11. The spacer 15 has a rectangular cross-section and is rod-shaped overall, as shown in Figure 6. The spacer 15 is provided at the position indicated by section D in Figure 2.

[0035] The spacer 15 is not for corner protection, but rather for suppressing pressure recovery during depressurization. Furthermore, since the spacer 15 is not for corner protection, it does not need to be installed at both ends inside the outer casing 11 (the two D sections in Figure 2), and it is sufficient to install it at at least one end (one of the two D sections in Figure 2).

[0036] As shown in Figure 6, when a spacer 15 is provided at the inner end of the outer casing 11, it is conceivable that the second outer casing 113 may not be located above or below the power generation element 12. The width W of the spacer 15 is set to a size corresponding to the amount of repressurized gas generated and to the minimum size that does not reduce the volumetric energy density. Although Figure 6 illustrates an example where the spacer 15 is provided on the energy storage module 1, the spacer 15 may also be provided on the energy storage module 1A.

[0037] According to the modified version 2 of the energy storage module having the above configuration, the strength of the corners can be increased by the folded structure of the outer casing 11, and the restoration of pressure during depressurization can be suppressed by providing the spacer 15.

[0038] 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.

[0039] For example, in Figures 1 to 6, the explanation was based on the assumption that the energy storage module according to the embodiment is a monopolar lithium-ion secondary battery, but the same structure can be applied even if the energy storage module according to the embodiment is a bipolar lithium-ion secondary battery. [Explanation of Symbols]

[0040] 1.1A Energy Storage Module 11,11A Outer casing 111,111A First exterior part 112,112A Folded section 113,113A Second exterior part 12 Power generation elements 13 Positive Tab Lead 14 Negative tab lead 15 Spacers

Claims

[Claim 1] Power generation elements, The outer casing covering the power generation element, Equipped with, The exterior body is, A first outer casing that covers the surface and corners of the power generation element, A folded portion extends continuously from the first outer casing, protruding from the side of the power generation element and folded back to the side of the power generation element, Continuing from the aforementioned folded portion, a second outer portion covers the corner of the first outer portion, A battery storage module.

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