Separator and battery pack

Abstract

To provide a separator that suppresses an excessive increase in reaction acting on a battery when a compression amount increases, and a battery pack comprising the same.SOLUTION: A separator comprises a base part, and a protrusion that protrudes in a first direction from the base part. The protrusion includes first and second parts that are integrally formed. The first part has a shape symmetrical about a first axis extending in the first direction. The second part has a shape asymmetrical about the first axis. In the protrusion, the volume of the first part is larger than that of the second part.SELECTED DRAWING: Figure 11

Description

Technical Field

[0001] The present technology relates to a separator and a battery module.

Background Art

[0002] A battery module in which a plurality of batteries are stacked and the stack is constrained has been conventionally known. As those disclosing conventional battery modules, Japanese Patent Application Laid-Open No. 2016-192520 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2023-518373 (Patent Document 2) can be cited.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a battery module constrained in the stacking direction, when the battery expands, a compressive force acts on a separator provided between the plurality of batteries, and the restraining force acting on the battery increases due to the reaction force. When the compression amount of the separator increases, it is required to suppress an excessive increase in the reaction force acting on the battery. The conventional structure is not necessarily sufficient from the above viewpoint.

[0005] An object of the present technology is to provide a separator in which an excessive increase in the reaction force acting on the battery is suppressed when the compression amount increases, and a battery module including the same.

Means for Solving the Problems

[0006] The present technology provides the following separator and battery module.

[0007] [1] A separator provided between a plurality of batteries arranged in a first direction or between a battery and an end plate, comprising a base portion and a protrusion portion protruding from the base portion in the first direction, the protrusion portion including a first portion and a second portion integrally formed therewith, the first portion having a shape symmetrical with respect to a first axis extending in the first direction, the second portion having a shape asymmetrical with respect to the first axis, and the volume of the first portion of the protrusion portion being larger than the volume of the second portion.

[0008] [2] The separator according to [1], wherein the first portion and the second portion are adjacent to each other in the first direction.

[0009] [3] The separator according to [1], wherein the first portion and the second portion are adjacent to each other in a second direction perpendicular to the first direction.

[0010] [4] The separator according to any one of [1] to [3], wherein the second portion is formed over the entire cross section of the protrusion in the first direction.

[0011] [5] The separator according to any one of [1] to [3], wherein the second portion is formed in a cross section of a part of the protrusion in the first direction.

[0012] [6] A battery pack comprising: a plurality of batteries arranged in the first direction; and the separator according to any one of [1] to [5] provided between the plurality of batteries. [Effects of the Invention]

[0013] According to the present technology, it is possible to provide a separator in which an excessive increase in reaction force when the amount of compression increases is suppressed, and a battery pack including the separator. [Brief explanation of the drawings]

[0014]

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Embodiments for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present technology will be described. In the following description, the same or corresponding parts may be denoted by the same reference numerals, and the description thereof may not be repeated.

[0016] In the embodiments described below, when referring to the number, amount, etc., unless otherwise specified, the scope of the present technology is not necessarily limited to the number, amount, etc. Also, in the following embodiments, each component is not necessarily essential for the present technology, unless otherwise specified. Further, the present technology is not limited to those that necessarily exhibit all the effects mentioned in the present embodiments.

[0017] In this specification, the descriptions of "comprise", "include", and "have" are in an open - ended form. That is, when a certain configuration is included, other configurations other than the said configuration may or may not be included.

[0018] Also, in this specification, when geometric terms and terms representing positional and directional relationships, such as "parallel", "orthogonal", "oblique 45°", "coaxial", "along", etc. are used, those terms allow for manufacturing errors or slight variations. When relative positional relationship terms such as "upper side" and "lower side" are used in this specification, those terms are used to indicate the relative positional relationship in one state, and the relative positional relationship can be reversed or rotated at an arbitrary angle depending on the installation direction of each mechanism (for example, turning the entire mechanism upside down, etc.).

[0019] As used herein, the "battery" is not limited to a lithium-ion battery, and may include other batteries such as nickel-metal hydride batteries and sodium-ion batteries. As used herein, the "electrode" may generically refer to a positive electrode and a negative electrode.

[0020] The "battery" herein can be mounted on a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), a battery electric vehicle (BEV), etc. However, the use of the "battery" is not limited to in-vehicle use.

[0021] FIG. 1 is a perspective view of a battery module according to the present embodiment. As shown in FIG. 1, the assembled battery 1 includes a battery 100 and a separator 200. The battery 100 and the separator 200 are alternately arranged along the Y-axis direction (the first direction).

[0022] The battery 100 is a rectangular battery cell, and a plurality of them are provided along the Y-axis direction. The plurality of batteries 100 are electrically connected to each other via a bus bar (not shown).

[0023] The separator 200 is provided between the plurality of batteries 100. The separator 200 is an insulating member that prevents unintentional electrical conduction between adjacent batteries 100. The separator 200 ensures electrical insulation between adjacent batteries 100. The separator 200 may also be provided between the battery 100 and an end plate (not shown).

[0024] FIG. 2 is a perspective view showing the battery 100. As shown in FIG. 2, the battery 100 has a rectangular shape. The battery 100 has an electrode terminal 110, a housing 120, and a gas discharge valve 130.

[0025] The electrode terminals 110 are formed on the housing 120. The electrode terminals 110 include a positive electrode terminal 111 and a negative electrode terminal 112 arranged along the X-axis direction (the second direction) orthogonal to the Y-axis direction (the first direction). The positive electrode terminal 111 and the negative electrode terminal 112 are provided apart from each other in the X-axis direction.

[0026] The housing 120 has a rectangular parallelepiped shape and forms the appearance of the battery 100. The housing 120 includes a case body 120A that houses an electrode body and an electrolytic solution (not shown) and a sealing plate 120B that seals the opening of the case body 120A. The sealing plate 120B is joined to the case body 120A by welding.

[0027] The housing 120 has an upper surface 121, a lower surface 122, a first side surface 123, a second side surface 124, and two third side surfaces 125.

[0028] The upper surface 121 is a plane orthogonal to the Z-axis direction (the third direction) orthogonal to the Y-axis direction and the X-axis direction. The electrode terminals 110 are arranged on the upper surface 121. The lower surface 122 faces the upper surface 121 along the Z-axis direction.

[0029] Each of the first side surface 123 and the second side surface 124 is a plane orthogonal to the Y-axis direction. Each of the first side surface 123 and the second side surface 124 has the largest area among the plurality of side surfaces of the housing 120. Each of the first side surface 123 and the second side surface 124 has a rectangular shape when viewed in the Y-axis direction. Each of the first side surface 123 and the second side surface 124 has a rectangular shape in which the X-axis direction is the longitudinal direction and the Z-axis direction is the short side direction when viewed in the Y-axis direction.

[0030] A plurality of batteries 100 are stacked such that the first side surfaces 123 face each other and the second side surfaces 124 face each other between adjacent batteries 100, 100 in the Y-axis direction. As a result, in the Y-axis direction in which the plurality of batteries 100 are stacked, the positive electrode terminals 111 and the negative electrode terminals 112 are arranged alternately.

[0031] The gas discharge valve 130 is provided on the upper surface 121. When the temperature of the battery 100 rises (thermal runaway) and the internal pressure of the housing 120 becomes equal to or higher than a predetermined value due to the gas generated inside the housing 120, the gas discharge valve 130 discharges the gas to the outside of the housing 120.

[0032] FIGS. 3 and 4 are front views of the separator 200. The separator 200 shown in FIG. 4 is a modified example of the separator 200 shown in FIG. 3. As shown in FIGS. 3 and 4, the separator 200 includes a base portion 210 and a protrusion portion 220 that protrudes in the Y-axis direction from the base portion 210.

[0033] The separator 200 can be made of a material having electrical insulation and elasticity. The separator 200 can be made of, for example, silicone rubber, fluororubber, urethane rubber, natural rubber, styrene-butadiene rubber, butyl rubber, ethylene-propylene rubber (EPM, EPDM), butadiene rubber, isoprene rubber, norbornene rubber, etc. The separator 200 can preferably be made of silicone rubber or fluororubber.

[0034] The hardness (Shore A hardness) of the material constituting the separator 200 is preferably about 30 or more and 90 or less, more preferably about 40 or more and 80 or less, and still more preferably about 50 or more and 70 or less.

[0035] The separator 200 according to the present embodiment has one feature in the shape or arrangement of the protrusion portion 220. Hereinafter, the aspect of the protrusion portion 220 will be described.

[0036] FIG. 5 is a diagram showing a protrusion portion 221 as an example of the protrusion portion provided on the separator 200, FIG. 6 is a cross-sectional view of the protrusion portion 221, FIG. 7 is a cross-sectional view showing a state where the protrusion portion 221 is compressed, and FIG. 8 is a diagram showing the relationship between the compression amount and the reaction force of the protrusion portion 222.

[0037] As shown in FIG. 5, the protrusion 221 has a substantially rectangular shape when viewed from the Y-axis direction, but the shape of the protrusion is not limited to this. As shown in FIGS. 6 and 7, the protrusion 221 has a cross-sectional shape that is symmetric with respect to the central axis 221A (first axis) extending in the Y-axis direction.

[0038] When a compressive force in the Y-axis direction is applied to the protrusion 221 from the state shown in FIG. 6, as shown in FIG. 7, the protrusion 221 is compressed while the central axis 221A maintains a linear shape. At this time, as shown in FIG. 8, as the amount of compression of the protrusion 221 increases, the reaction force also increases.

[0039] FIG. 9 is a view showing a protrusion 222 as another example of the protrusion provided on the separator 200, FIG. 10 is a cross-sectional view of the protrusion 222, FIG. 11 is a cross-sectional view showing a state in which the protrusion 222 is compressed, and FIG. 12 is a view showing the relationship between the amount of compression and the reaction force of the protrusion 222.

[0040] As shown in FIG. 9, the protrusion 222 has a substantially rectangular shape when viewed from the Y-axis direction. As shown in FIGS. 10 and 11, the protrusion 222 includes a main body portion 222B (first portion) having a cross-sectional shape that is symmetric with respect to the central axis 222A (first axis) extending in the Y-axis direction, and an asymmetric portion 222C that further protrudes from a part of the tip in the Y-axis direction and has an asymmetric shape with respect to the central axis 222A.

[0041] The main body portion 222B and the asymmetric portion 222C are integrally formed. In the protrusion 222, the volume of the main body portion 222B is larger than the volume of the asymmetric portion 222C.

[0042] When a compressive force in the Y-axis direction is applied to the protrusion 222 from the state shown in FIG. 10 and the compressive force exceeds a predetermined magnitude, as shown in FIG. 11, the central axis 222A of the protrusion 222 is deformed so as to bend. That is, when a compressive force exceeding a predetermined magnitude acts on the protrusion 222, the columnar protrusion 222 buckles. As shown in FIG. 12, in the region where the buckling load is exceeded, the amount of compression increases with a small load.

[0043] In the protrusions 220 of the separator 200 according to the present embodiment, by mixing the above-described protrusions 221 and 222, it is possible to suppress an excessive increase in the reaction force acting on the battery 100 when the compression amount of the separator 200 increases while ensuring the minimum necessary compression reaction force.

[0044] The arrangement and shape of the protrusions 221 and 222 in the separator 200 can be appropriately changed.

[0045] FIGS. 13 to 18 are cross-sectional views showing modified examples of the protrusion 222. As shown in FIG. 13, the asymmetric portion 222C may have a shape that protrudes in a tapered manner from the main body portion 222B in the Y-axis direction. At this time, the main body portion 222B and the asymmetric portion 222C are adjacent to each other in the Y-axis direction.

[0046] As shown in FIGS. 14 and 15, the asymmetric portion 222C may have a shape that protrudes in a tapered manner from the main body portion 222B in the X-axis direction. At this time, the main body portion 222B and the asymmetric portion 222C are adjacent to each other in the X-axis direction.

[0047] The asymmetric portion 222C may be formed only on one side in the X-axis direction with respect to the main body portion 222B (FIG. 14), or may be formed on both sides in the X-axis direction with respect to the main body portion 222B (FIG. 15). The asymmetric portion 222C may be formed over the entire Y-axis direction (FIG. 14), or may be formed on a part of the Y-axis direction (FIG. 15).

[0048] Even when the cross-sectional shape forming the asymmetric portion 222C is a rectangular shape, it is not limited to the example of FIG. 10, and may have a shape as illustrated in FIGS. 16 and 17. Further, as shown in FIG. 18, when viewed from the Y-axis direction, the asymmetric portion 222C may be formed by forming a concave portion 222D that opens in the X-axis direction in a part of the columnar protrusion 222. The concave portion 222D may open in the Z-axis direction. At this time, as indicated by the arrow in FIG. 18, deformation in the direction closing the opening of the concave portion 222D is promoted.

[0049] Figs. 19 to 22 are front views showing other modified examples of the separator 200, and each shows a modified example of the arrangement of the protrusions 220 in the separator 200.

[0050] As in the example of Fig. 19, the shape of the protrusion 220 may be a combination of a rectangular shape and a tapered shape. As in the example of Fig. 20, the protrusion 220 may be elongated when viewed from the Y-axis direction. In the example of Fig. 20, the Z-axis direction is the longitudinal direction and the X-axis direction is the short-side direction, but it may be the reverse, or the longitudinal direction may be an oblique direction (a direction intersecting both the X-axis direction and the Z-axis direction).

[0051] As in the example of Fig. 21, the protrusion 220 may have a shape in which a hole 223 is provided inside a rectangular shape. The hole 223 may be singular or plural. The number and arrangement of the holes 223 can be changed as appropriate. Also, as in the example of Fig. 22, a recess 224 may be provided in a part of the outer edge of the hole 223.

[0052] In the example of Fig. 22, the periphery of the hole 223 in which the recess 224 is formed is likely to be deformed, and this part is likely to buckle. That is, in the example of Fig. 22, the part located around the recess 224 constitutes the "asymmetric part" of the protrusion 220.

[0053] FIG. 23 illustrates a state in which protrusions 221, 222 are compressed while contacting each other. As shown in FIG. 23(A), protrusion 221 without an asymmetrical portion and protrusion 222 with an asymmetrical portion are adjacently disposed at a distance equal to or less than the height of the protrusion. When a compressive force is applied to protrusion 220 from the state shown in FIG. 23(A), protrusion 221 is compressed while remaining substantially upright, while protrusion 222 buckles and is compressed while tilting toward protrusion 221, as shown in FIG. 23(B). When the compressive force acting on protrusion 220 is further increased from the state shown in FIG. 23(B), protrusion 222, which has buckled and tilted, comes into contact with protrusion 221, as shown in FIG. 23(C). Compression proceeds as protrusion 222 tilts protrusion 221. This configuration prevents an excessive increase in the reaction force acting on battery 100 when the separator 200 is compressed to an increased degree.

[0054] In this case, a protrusion 221 without an asymmetric portion can be provided on the separator 200 facing the peripheral edge of the battery 100, so that it will not come into contact with the protrusion 222 with an asymmetric portion even if it buckles. Even if the protrusion 222 with an asymmetric portion buckles, the protrusion 221 without an asymmetric portion in this portion will not buckle, so that a distance can be maintained between adjacent batteries 100.

[0055] Fig. 24 is a diagram schematically showing an apparatus for determining the relationship between the compressibility and load of separator 200. Fig. 25 is a diagram showing the relationship between the compressibility and load of separator 200.

[0056] 24, separator 200 is compressed using jig 300, and the relationship between load F (reaction force) and compression ratio at that time is determined. The compression ratio is determined by the following formula. Compression ratio = (L0-L) / L0

[0057] 25, the slope of the compression rate-load curve up to the compression rate of 0.2 (20 percent) is defined as the "spring constant" of separator 200. The "spring constant" of separator 200 according to this embodiment is preferably about 1 MPa or more and 10 MPa or less.

[0058] As described above, the embodiments of the present technology have been explained. However, it should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present technology is indicated by the claims, and all modifications within the meaning and scope equivalent to the claims are intended to be included.

Explanation of Reference Numerals

[0059] 1 battery pack, 100 battery, 110 electrode terminal, 111 positive electrode terminal, 112 negative electrode terminal, 120 housing, 120A case body, 120B sealing plate, 121 upper surface, 122 lower surface, 123 first side surface, 124 second side surface, 125 third side surface, 130 gas discharge valve, 200 separator, 210 base portion, 220, 221, 222 protrusion, 221A, 222A central axis, 222B body portion, 222C asymmetric portion, 222D recess, 223 hole portion, 224 recess, 300 jig.

Claims

1. A separator provided between a plurality of batteries arranged in a first direction or between a battery and an end plate, comprising a base portion, and a protrusion protruding from the base portion in the first direction, wherein the protrusion includes an integrally formed first portion and a second portion, the first portion has a shape symmetric with respect to a first axis extending in the first direction, the second portion has a shape asymmetric with respect to the first axis, and in the protrusion, the volume of the first portion is larger than the volume of the second portion.

2. The separator according to claim 1, wherein the first portion and the second portion are adjacent to each other in the first direction.

3. The separator according to claim 1, wherein the first portion and the second portion are adjacent to each other in a second direction orthogonal to the first direction.

4. The separator according to any one of claims 1 to 3, wherein the second portion is formed over all cross-sections of the protrusion in the first direction.

5. The separator according to any one of claims 1 to 3, wherein the second portion is formed in a partial cross-section of the protrusion in the first direction.

6. A battery pack comprising a plurality of batteries arranged in the first direction, and the separator according to any one of claims 1 to 3 provided between the plurality of batteries.

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