Protective sheet member and battery unit equipped therewith

Abstract

To suppress advancing of a metal piece from the outside or the inside of a battery cell and protect the battery cell from vibration during steady traveling.SOLUTION: The present invention relates to a protection sheet member 30 is used for enveloping one or two or more battery cells 20 in a battery unit for storing a plurality of battery cells 20, the protection sheet member 30 including: a fiber member 32 which is made of synthetic fibers or contains synthetic fibers; and a rubber-like elastic sheet 31 which is fixed to at least one surface of the fiber member 32, and the battery unit including the protection sheet member 30.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a protective sheet member and a battery unit including the same.

Background Art

[0002] The power source of automobiles is shifting from engines using fossil fuels such as gasoline and light oil to motors using electricity from batteries. In a lithium-ion battery, which is one type of battery, generally, a plurality of battery cells (also simply referred to as "cells") are arranged in a housing.

[0003] In an electric vehicle, a battery unit equipped with a plurality of battery cells is generally arranged at the bottom of the vehicle body, that is, below the seat. A method of installing a protective plate between the battery unit and the road is known to protect the battery cells from small stones or the like that are rolled up from the road (see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When an automobile accident occurs, as a method of protecting battery cells, in addition to a method of increasing the strength of the box storing the battery cells, a method of providing a circuit breaker function that detects a large impact and turns off the power supply has been conventionally known. Even when such a method is adopted, due to damage to the box accompanying an automobile accident, a part of the box becomes a sharp blade and pierces the container of the battery cell, causing the outflow of the internal electrolyte, and as a result, the risk of a secondary disaster in which the battery cell ruptures still remains.

[0006] Furthermore, it is known that when battery cells become abnormally hot during charging and discharging, the container that makes up the battery cell expands. This expansion of the container may lead to the container rupturing and scattering of fragments outside the battery unit.

[0007] The protective plate disclosed in Patent Document 1 is merely a component for protecting the entire battery from small stones and other debris from outside the vehicle (e.g., from the road). Therefore, such a protective plate cannot prevent damage to the container due to car accidents or overheating and expansion of the battery cells. In addition, it is also important to protect the battery cells from vibrations during steady-state driving.

[0008] This invention was made to solve the above problems, and aims to suppress the progression of fragments from the outside or inside of the battery cell, as well as to protect the battery cell from vibrations during steady-state driving. [Means for solving the problem]

[0009] (1) A protective sheet member according to one embodiment for achieving the above objective is a protective sheet member for covering one or more battery cells in a battery unit containing a plurality of battery cells, A fibrous member made of synthetic fibers or containing synthetic fibers, A rubber-like elastic sheet fixed to at least one surface of the fiber member, It is equipped with. (2) In a protective sheet member according to another embodiment, preferably the rubber-like elastic sheet may be fixed to both sides of the fiber member. (3) Another protective sheet member according to another embodiment may be a protective sheet member according to any of the above embodiments, preferably an inverted cup-shaped molded body that covers the parts of one or more battery cells other than the bottom. (4) Another protective sheet member according to another embodiment may be a molded body that covers the top of one or more battery cells and one or more outer surfaces, in any of the protective sheet members according to the above embodiment. (5) In a protective sheet member according to another embodiment, in a protective sheet member according to any of the above embodiments, preferably the synthetic fiber may be a modified polyphenylene ether resin fiber or an aramid fiber. (6) In a protective sheet member according to another embodiment, in a protective sheet member according to any of the above embodiments, preferably the rubber-like elastic sheet may be a silicone rubber sheet. (7) In a protective sheet member according to another embodiment, preferably the silicone rubber sheet may be a porous sheet. (8) A battery unit according to one embodiment for achieving the above objective is: Container and A lid that covers the container, Multiple battery cells are housed in the space formed inside the container and the lid, A battery unit comprising at least the following: One of the above-mentioned protective sheet members is placed in the gap between the top of one or more of the battery cells and the lid, and on the outer surface of one of the battery cells or on the outer surface of one or more of the battery cell groups consisting of two or more of the battery cells. (9) In a battery unit according to another embodiment, preferably the protective sheet member may enclose the entire battery cell or the group of battery cells. (10) In a battery unit according to another embodiment, in a battery unit according to any of the above embodiments, preferably, one or more insulating sheet members may be arranged between the upper part of one or more battery cells and the protective sheet member. [Effects of the Invention]

[0010] According to the present invention, it is possible to suppress the progress of fragments from the outside or inside of the battery cell and protect the battery cell from vibrations during steady running.

Brief Description of the Drawings

[0011] [Figure 1] FIG. 1 shows a perspective view partially disclosing the interior of a battery unit according to an embodiment of the present invention. [Figure 2] FIG. 2 shows a perspective view of a situation where the battery cell group of FIG. 1 is covered with a protective sheet member and an enlarged view of a part A of a side end face of the protective sheet member. [Figure 3] FIG. 3 shows a perspective view of a state where, proceeding from the situation of FIG. 2, parts other than the bottom of the battery cell group are covered with a protective sheet member. [Figure 4] FIG. 4 shows a perspective view of a situation where the battery cell group of FIG. 1 is covered with a different protective sheet member from that of FIG. 2. [Figure 5] FIG. 5 shows a perspective view of a state where, proceeding from the situation of FIG. 4, parts other than the bottom of the battery cell group are covered with a protective sheet member. [Figure 6] FIG. 6 shows a longitudinal sectional view of a modified example of a structure in which the formed protective sheet member of FIG. 5 is placed over the upper part of the battery cell group and an enlarged view of a part B. [Figure 7] FIG. 7 shows a longitudinal sectional view of modified example 1 of the structure of FIG. 6 and an enlarged view of a part C (7A), and a longitudinal sectional view of modified example 2 of the structure of FIG. 6 and an enlarged view of a part D (7B).

Modes for Carrying Out the Invention

[0012] Next, embodiments of the present invention will be described with reference to the drawings. Note that the embodiments described below do not limit the invention according to the claims, and not all of the elements and combinations thereof described in the embodiments are essential for the solution means of the present invention.

[0013] FIG. 1 shows a perspective view partially disclosing the interior of a battery unit according to an embodiment of the present invention. In FIG. 1, a part of the lid is omitted to enable visual recognition of the interior of the battery unit.

[0014] The battery unit 1 according to this embodiment is, for example, a battery for an electric vehicle and includes a number of battery cells (which may simply be referred to as “cells”). The battery unit 1 includes at least a metal container 10, a metal lid 11, and a plurality of battery cells 20 stored in a space formed inside by the container 10 and the lid 11. The container 10 and the lid 11 can be closed with a seal member sandwiched between the peripheral edges of their openings. The container 10 and the lid 11 are made of a metal material in this embodiment, but may be made of a material other than metal, for example, a resin or a ceramic material. The battery unit 1 further has a protective sheet member 30 (or 40) disposed in the gap between the upper part of one or two or more battery cells 20 and the lid 11, and on the outer surface of one battery cell 20 or the outer surface of a battery cell group 25 composed of two or more battery cells 20. The protective sheet member 30 has the form of a flexible sheet. The protective sheet member 40 has the form of a molded body obtained by shaping a sheet. The battery unit 1 may be provided with either type of member of the protective sheet members 30 and 40.

[0015] The protective sheet member 30 (or 40) is a member for covering one or more battery cells 20 within a battery unit 1 that houses multiple battery cells 20. The protective sheet member 30 (or 40) does not necessarily have to cover all outer surfaces of the battery cells 20 or all outer surfaces of the battery cell group 25; it may cover one or more of the outer surfaces of the battery cells 20 or battery cell group 25. Furthermore, the protective sheet member 30 (or 40) may be positioned within the battery unit 1 to enclose not only the battery cells 20 or battery cell group 25, but also cooling plates located at the bottom of the battery cells 20 or battery cell group 25. Thus, the protective sheet member 30 (or 40) may enclose the entire battery cells 20 or battery cell group 25.

[0016] Figure 2 shows a perspective view of the battery cell group in Figure 1 covered with a protective sheet member, and an enlarged view of a part A of the side end face of the protective sheet member. Figure 3 shows a perspective view of the battery cell group, further developed from the situation in Figure 2, with the protective sheet member covering everything except the bottom.

[0017] The battery cell group 25 is an assembly of two or more battery cells 20 arranged in a row. The battery cells 20 may be arranged in a single row in the width direction, or in two or more rows. In this embodiment, a fire-spread prevention sheet 21 is placed between the battery cells 20. The fire-spread prevention sheet 21 is a sheet that minimizes the spread of fire to adjacent battery cells 20 even if one battery cell 20 overheats and, in the worst case, ignites. The fire-spread prevention sheet 21 may be made only of highly heat-resistant silicone rubber, or a sheet with a plate-like member having better heat resistance than the silicone rubber on one or both sides of the silicone rubber. However, the fire-spread prevention sheet 21 is not an essential component of the battery cell group 25 and does not have to be provided in the battery cell group 25.

[0018] In this application, the battery cell 20 is provided with two electrodes 22 on its upper surface. The side on which the electrodes 22 are located is referred to as the "upper part" or "upper surface" of the battery cell 20 or battery cell group 25. The side of the battery cell 20 or battery cell group 25 opposite to the upper part or upper surface is referred to as the "bottom part" or "bottom surface." The parts of the battery cell 20 or battery cell group 25 other than the upper part (or upper surface) and the bottom part (or bottom surface) are referred to as the "outer surface."

[0019] As shown in the enlarged view of a part A of the side end face of the protective sheet member in Figure 2, the protective sheet member 30 comprises a fiber member 32 made of synthetic fibers or containing synthetic fibers, and a rubber-like elastic sheet 31 fixed to both sides of the fiber member 32. The fiber member 32 may be a woven fabric made of synthetic fibers, a nonwoven fabric in which synthetic fibers are intertwined without weaving, or a synthetic fiber dispersed resin in which synthetic fibers are dispersed in a resin, and is preferably a woven fabric from the viewpoint of improving strength. The protective sheet member 30 is a single flexible sheet that can cover all but the bottom of the battery cell group 25, i.e., the top and the four outer surfaces.

[0020] The synthetic fibers constituting the fiber member 32 include any fiber that is stronger than the rubber-like elastic sheet 31. Examples of synthetic fibers include aramid fibers (especially para-aramid fibers), polyarylate fibers, modified polyphenylene ether resin fibers, or ultra-high-strength polyethylene fibers. Among these examples of fibers, modified polyphenylene ether resin fibers or aramid fibers are more preferred. Examples of modified polyphenylene ether resin fibers include PPE / PS alloys, PA / PPE alloys, PP / PPE alloys, and PPS / PPE alloys. PPE / PS alloys are perfectly compatible alloys. PA / PPE alloys, PP / PPE alloys, and PPS / PPE alloys are incompatible alloys.

[0021] The rubber-like elastic sheet 31 is composed of, for example, thermosetting elastomers such as silicone rubber, urethane rubber, isoprene rubber, ethylene propylene rubber, natural rubber, ethylene propylene diene rubber, nitrile rubber (NBR), or styrene butadiene rubber (SBR); thermoplastic elastomers such as urethane-based, ester-based, styrene-based, olefin-based, butadiene-based, and fluorine-based elastomers, or composites thereof. As the rubber-like elastic sheet 31, in addition to ethylene propylene rubber, a silicone rubber sheet with excellent heat resistance is preferred. Furthermore, as the rubber-like elastic sheet 31, a porous sheet (also called a sponge sheet) with high elasticity is preferred. In this embodiment, a porous sheet made of silicone rubber is used as a more preferred form of the rubber-like elastic sheet 31.

[0022] The protective sheet member 30 has a three-layer structure in which rubber-like elastic sheets 31 are fixed to both sides of a fiber member 32, and therefore exhibits the following effects. First, by providing the protective sheet member 30 with rubber-like elastic sheets 31, vibrations during steady-state driving can be reduced by the rubber-like elastic sheets 31, and the battery cells 20 can be protected from vibration. The hardness of the rubber-like elastic sheet 31 is preferably 10° to 80° according to the hardness scale of JIS K 6253. It is also preferable to use a foamed elastic body with a specific gravity of 0.2 to 0.6 as the rubber-like elastic sheet 31. Furthermore, a hardness in the range of 0.1 to 0.2 MPa when compressed is desirable. As a result, sufficient softness to protect the battery cells 20 when an impact occurs and sufficient shock absorption can be achieved. The preferred thickness of the rubber-like elastic sheet 31 on the side closer to the battery cells 20 (referred to as the cell-side elastic body) is 7 to 15 mm, more preferably 9 to 12 mm. The cell-side elastic body is required to maintain a sufficient insulation distance from the electrodes 22 of the battery cell 20, and also to absorb the irregularities of the busbars (not shown) connecting the electrodes 22. From this viewpoint, the thickness of the cell-side elastic body is preferably within the above range. On the other hand, the rubber-like elastic sheet 31 on the lid 11 side only needs to be able to absorb vibrations transmitted from the outside and satisfy a cushioning function against minor impacts. For this reason, its thickness is preferably 2 to 7 mm, more preferably 4 to 6 mm.

[0023] The fiber member 32 has the effect of reducing risks that cannot be prevented by the rubber-like elastic sheet 31. One such risk is that the battery unit 1 may be damaged in an automobile accident, and some of it may break off as metal fragments or the like, piercing the container of the battery cell 20. Another risk is that the battery cell 20 may expand due to abnormal overheating, causing its container to rupture and releasing metal fragments or the like, which may pierce the container of another battery cell 20. Because the fiber member 32 is tougher than the rubber-like elastic sheet 31, it can reduce the risk of such fragments penetrating the protective sheet member 30. There are no particular restrictions on the thickness of the fiber member 32. Even if the thickness of the fiber member 32 is less than the thickness of the rubber-like elastic sheet 31, sufficient cut-resistant effect can be obtained. From the viewpoint of making the protective sheet member 30 as thin as possible, the preferred thickness of the fiber member 32 is 0.3 to 1.0 mm, and a more preferred thickness is 0.4 to 0.6 mm.

[0024] There are no particular restrictions on the method of fixing the fiber member 32 and the rubber-like elastic sheet 31. A preferred fixing method is adhesion. As the adhesive, an adhesive that can hold the rubber-like elastic sheet 31 after curing is preferred, such as a silicone RTV adhesive. This allows the adhesive to intertwine with the fibers of the fiber member 32, enabling high-strength adhesion. An example of an adhesion method is to print the adhesive onto the rubber-like elastic sheet 31 using a silkscreen method, attach the fiber member 32 to it, and leave it to cure. The adhesive can be used after diluting it with a solvent such as acetone.

[0025] Figure 4 shows a perspective view of the battery cell group in Figure 1 being covered with a different protective sheet material than that used in Figure 2. Figure 5 shows a perspective view of the battery cell group in which all parts except the bottom are covered with the protective sheet material, progressing from the situation in Figure 4.

[0026] The protective sheet member 40 shown in Figures 4 and 5 is not a single flexible sheet like the protective sheet member 30 described above, but an inverted cup-shaped molded body that covers all but the bottom of one or more battery cells 20 (including groups of two or more battery cells 25). The protective sheet member 40 is the same as the protective sheet member 30 in terms of material, thickness, etc., except that it is in a pre-molded form. The method of fixing the rubber-like elastic sheet 31 and the fiber member 32 may be adhesive-free. The protective sheet member 40 has an opening 45 for inserting the battery cell group 25.

[0027] Figure 6 shows a longitudinal cross-sectional view and a magnified view of a part of B of a modified structure in which the molded protective sheet member from Figure 5 is placed over the battery cell group from above.

[0028] The protective sheet member 40 in the structure of Figure 6 is the same as the protective sheet member 40 in Figure 5. The structure of Figure 6 differs from the structure of Figure 5 in that it is equipped with an insulating film 50 and an insulating sheet 51 on top of the battery cell group 25 (above the electrodes 22). The insulating film 50 covers the electrodes 22. The insulating sheet 51 is placed on top of the insulating film 50. The insulating sheet 51 is preferably thicker than the insulating film 50. The insulating film 50 and insulating sheet 51 are placed between the battery cell group 25 and the protective sheet member 40 to prevent electrical contact between the electrodes 22 and unintended current flow between the electrodes 22 and external components. The insulating film 50 and insulating sheet 51 are examples of insulating sheet members. A polyimide film can be exemplified as the insulating film 50. A resin sheet such as polyolefin, polyamide, polyimide, polyethylene terephthalate, or polycarbonate can be exemplified as the insulating sheet 51. Thus, in the battery unit 1 of Figure 1, one or more insulating sheet members, such as an insulating film 50 and / or insulating sheet 51, can be placed between the top of one or more battery cells 20 and the protective sheet member 40.

[0029] Figure 7 shows a longitudinal section view and a magnified view of part C (7A) of modified example 1 of the structure in Figure 6, and a longitudinal section view and a magnified view of part D (7B) of modified example 2 of the structure in Figure 6.

[0030] The difference between the structure of (7A) and the structure of Figure 6 is that the protective sheet member 40a has a two-layer structure consisting of a fiber member 32 and a rubber-like elastic sheet 31. Similarly, the difference between the structure of (7B) and the structure of Figure 6 is that the protective sheet member 40b has a two-layer structure consisting of a fiber member 32 and a rubber-like elastic sheet 31. The protective sheet member 40a has the fiber member 32 on the side of the battery cell group 25. On the other hand, the protective sheet member 40b has the rubber-like elastic sheet 31 on the side of the battery cell group 25.

[0031] Thus, unlike the protective sheet member 40 in Figure 2, the protective sheet members 40a and 40b have a two-layer structure consisting of a fiber member 32 and a single rubber-like elastic sheet 31. Even with such a two-layer structure, the protective sheet members 40a and 40b can exhibit the effect of reducing the transmission of vibrations during steady operation to the battery cell 20 and the effect of suppressing the movement of fragments such as metal pieces caused by automobile accidents or abnormal expansion of battery cells. However, a three-layer structure like that of the protective sheet member 40 is preferable.

[0032] The battery unit 1 in Figure 1 allows for the placement of one or more insulating sheet members, such as an insulating film 50 and / or insulating sheet 51, between the top of one or more battery cells 20 and a protective sheet member 40a (or protective sheet member 40b).

[0033] The present invention is not limited to the embodiments described above and can be modified in various ways.

[0034] The protective sheet members 30, 40, 40a, and 40b (referred to as protective sheet members 30, etc.) are sheets or molded bodies that cover the top and one or four outer surfaces of one or more battery cells 20. The protective sheet members 30, etc. are not limited to sheets or molded bodies that cover four outer surfaces, but may also be sheets or molded bodies that cover the top and one, two, or three outer surfaces of the battery cell 20. Furthermore, if the battery cell 20 is not a rectangular parallelepiped but has a polygonal prism shape with a top and bottom surface of five or more sides, the number of outer surfaces will be five or more. In such cases, the protective sheet members 30, etc. may cover all or part of those outer surfaces. Note that the battery cell 20 covered by the protective sheet members 30, etc. may be read as a battery cell group 25, which is an assembly of two or more battery cells 20. [Industrial applicability]

[0035] This invention can be used, for example, in automobile batteries. [Explanation of symbols]

[0036] 1...Battery unit, 10...Container, 11...Lid, 20...Battery cell, 21...Fire prevention sheet, 22...Electrode, 25...Battery cell group, 30, 40, 40a, 40b...Protective sheet material, 31...Rubber-like elastic sheet, 32...Fiber material, 50...Insulating film (example of insulating sheet material), 51...Insulating sheet (example of insulating sheet material).

Claims

1. A protective sheet member for covering one or more battery cells in a battery unit containing multiple battery cells, A fibrous member made of synthetic fibers or containing synthetic fibers, A rubber-like elastic sheet fixed to at least one surface of the fiber member, Equipped with, A protective sheet member characterized by being an inverted cup-shaped molded body that covers all but the bottom of one or more of the battery cells.

2. The protective sheet member according to claim 1, characterized in that the rubber-like elastic sheet is fixed to both sides of the fiber member.

3. The protective sheet member according to claim 1, characterized in that it is a molded body that covers the upper part and one or more outer surfaces of one or more of the battery cells.

4. The protective sheet member according to claim 1, characterized in that the synthetic fiber is a modified polyphenylene ether resin fiber or an aramid fiber.

5. The protective sheet member according to claim 1, characterized in that the rubber-like elastic sheet is a silicone rubber sheet.

6. The protective sheet member according to claim 5, characterized in that the silicone rubber sheet is a porous sheet.

7. Container and A lid that covers the container, Multiple battery cells are housed in the space formed inside the container and the lid, A battery unit comprising at least the following: The gap between the top of one or more of the battery cells and the lid, and the outer surface of one of the battery cells or the outer surface of one or more of the battery cell group consisting of two or more of the battery cells, A protective sheet member for covering one or more battery cells within a battery unit containing multiple battery cells, comprising a fibrous member made of synthetic fiber or containing synthetic fiber, and a rubber-like elastic sheet fixed to at least one surface of the fibrous member, A battery unit characterized in that one or more insulating sheet members are arranged between the upper parts of one or more battery cells and the protective sheet member.

8. The battery unit according to claim 7, characterized in that the protective sheet member encloses the entire battery cell or the group of battery cells.

9. The battery unit according to claim 7, characterized in that the protective sheet member is an inverted cup-shaped molded body that covers all but the bottom of one or more of the battery cells.

10. The battery unit according to claim 7, wherein the protective sheet member is characterized in that the rubber-like elastic sheet is fixed to both sides of the fiber member.

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