Separator and battery pack

Abstract

The separator (200) is provided with a base portion (210) and a protrusion portion (222) protruding from the base portion (210) in a first direction, the protrusion portion (222) includes a first portion (222B) and a second portion (222C) integrally formed, the first portion (222B) has a shape symmetrical about a first axis (222A) extending in the first direction, the second portion (222C) has a shape asymmetrical about the first axis (222A), and in the protrusion portion (222), the volume of the first portion (222B) is larger than the volume of the second portion (222C).

Description

Technical Field

[0001] The present technology relates to a separator and a battery pack. Background Art

[0002] There has been conventionally known a battery pack in which a plurality of batteries are laminated and the laminate is bound. As documents disclosing conventional battery packs, Japanese Patent Application Laid-Open No. 2016-192520 and Japanese Patent Application Laid-Open No. 2023-518373 can be cited. Summary of the Invention

[0003] In a battery pack bound in the stacking direction, if the battery expands, a compressive force acts on the separator provided between the plurality of batteries, and due to the reaction force, the binding force acting on the battery increases. It is desired to suppress an excessive increase in the reaction force acting on the battery when the compression amount of the separator increases. From the above viewpoints, the conventional structures are not sufficient to cope with this.

[0004] An object of the present technology is to provide a separator that can suppress an excessive increase in the reaction force acting on the battery when the compression amount increases, and a battery pack including the separator.

[0005] The present technology provides the following separator and battery pack.

[0006] [1] A separator provided between a plurality of batteries arranged in a first direction or between a battery and an end plate, wherein the separator includes: a base portion; and a protrusion portion that protrudes from the base portion in the first direction, the protrusion portion includes a first portion and a second portion formed integrally, the first portion has a shape symmetric about a first axis extending in the first direction, the second portion has a shape asymmetric about the first axis, and in the protrusion portion, the volume of the first portion is larger than the volume of the second portion.

[0007] [2] The separator according to [1], wherein the first portion and the second portion are adjacent to each other in the first direction.

[0008] [3] The separator according to [1], wherein the first portion and the second portion are adjacent to each other in a second direction orthogonal to the first direction.

[0009] [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 portion in the first direction.

[0010] [5] The separator according to any one of [1] to [3], wherein the second portion is formed in a part of the cross-section of the protrusion portion in the first direction.

[0011] [6] A battery pack, wherein the battery pack includes: a plurality of batteries arranged along the first direction; and the separator according to any one of [1] to [5], the separator being provided between the plurality of batteries.

[0012] The above and other objects, features, configurations, and advantages of the present invention will become apparent from the following detailed description of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a perspective view showing the battery pack.

[0014] Figure 2 is a perspective view of the battery constituting the battery pack.

[0015] Figure 3 is a front view of the separator constituting the battery pack.

[0016] Figure 4 is a front view of a modified example of the separator.

[0017] Figure 5 is a view showing an example of the protrusion provided on the separator.

[0018] Figure 6 is Figure 5 a cross-sectional view of the shown protrusion.

[0019] Figure 7 is a view showing Figure 5 the state where the shown protrusion is compressed.

[0020] Figure 8 is a view showing Figure 5 the relationship between the compression amount and the reaction force of the shown protrusion.

[0021] Figure 9 is a view showing another example of the protrusion provided on the separator.

[0022] Figure 10 is Figure 9 a cross-sectional view of the shown protrusion.

[0023] Figure 11 is a view showing Figure 9 the state where the shown protrusion is compressed.

[0024] Figure 12 is a view showing Figure 9 the relationship between the compression amount and the reaction force of the shown protrusion.

[0025] Figure 13 is a cross-sectional view (Part 1) showing a modified example of the protrusion.

[0026] Figure 14 It is a cross-sectional view (the second one) showing a modified example of the protrusion.

[0027] Figure 15 It is a cross-sectional view (the third one) showing a modified example of the protrusion.

[0028] Figure 16 It is a cross-sectional view (the fourth one) showing a modified example of the protrusion.

[0029] Figure 17 It is a cross-sectional view (the fifth one) showing a modified example of the protrusion.

[0030] Figure 18 It is a cross-sectional view (the sixth one) showing a modified example of the protrusion.

[0031] Figure 19 It is a front view (the first one) showing another modified example of the partition plate.

[0032] Figure 20 It is a front view (the second one) showing another modified example of the partition plate.

[0033] Figure 21 It is a front view (the third one) showing another modified example of the partition plate.

[0034] Figure 22 It is a front view (the fourth one) showing another modified example of the partition plate.

[0035] Figures 23A to 23C It is a diagram showing a state where the protrusions are compressed while being in contact with each other on one side.

[0036] Figure 24A And Figure 24B It is a diagram schematically showing a device for obtaining the relationship between the compression rate and the load of the partition plate.

[0037] Figure 25 It is a diagram showing the relationship between the compression rate and the load of the partition plate. Detailed implementation mode

[0038] Hereinafter, the implementation modes of the present technology will be described. In addition, the same or equivalent parts are denoted by the same reference numerals, and the description thereof may not be repeated sometimes.

[0039] In addition, in the implementation modes described below, when referring to the number, quantity, etc., unless otherwise specified, the scope of the present technology does not have to be limited to that number, quantity, etc. In addition, in the following implementation modes, each constituent element is not an essential constituent for the present technology unless otherwise specified. In addition, the present technology is not limited to a configuration that necessarily exhibits all the effects mentioned in the present implementation mode.

[0040] In addition, in this specification, the descriptions such as "comprise", "include", and "have" are not restrictive forms. That is, when including a certain component, other components other than this component may or may not be included.

[0041] In addition, in this specification, when using geometric terms and terms indicating positional and directional relationships such as "parallel", "orthogonal", "oblique 45°", "coaxial", "along", etc., these terms allow manufacturing errors or slight variations. In this specification, when using terms indicating relative positional relationships such as "upper side" and "lower side", these terms are used as terms indicating relative positional relationships in one state, and according to the installation direction of each mechanism (for example, turning the entire mechanism upside down), the relative positional relationship can be reversed or rotated at any angle.

[0042] In this specification, the "battery" is not limited to lithium-ion batteries, and may also include other batteries such as nickel-metal hydride batteries and sodium-ion batteries. In this specification, the positive electrode and the negative electrode may be collectively referred to as "electrodes".

[0043] The "battery" in this specification can be mounted on a hybrid electric vehicle (HEV: Hybrid Electric Vehicle), a plug-in hybrid electric vehicle (PHEV: Plug-in Hybrid Electric Vehicle), a battery electric vehicle (BEV: Battery Electric Vehicle), etc. However, the use of the "battery" is not limited to on-vehicle use.

[0044] Figure 1 It is a perspective view of the battery module according to the embodiment. As Figure 1 shown, the battery pack 1 includes the battery 100 and the separator 200. The battery 100 and the separator 200 are alternately arranged along the Y-axis direction (the first direction).

[0045] The battery 100 is a square battery cell, and a plurality of them are arranged along the Y-axis direction. The plurality of batteries 100 are electrically connected to each other via a bus bar (not shown).

[0046] The separator 200 is provided between the plurality of batteries 100. The separator 200 is an insulating member that prevents accidental conduction between adjacent batteries 100. The separator 200 ensures the electrical insulation between adjacent batteries 100. The separator 200 may also be provided between the battery 100 and an end plate (not shown).

[0047] Figure 2 It is a perspective view showing the battery 100. As Figure 2As shown, the battery 100 has a square shape. The battery 100 has electrode terminals 110, a casing 120, and a gas discharge valve 130.

[0048] The electrode terminals 110 are formed on the casing 120. The electrode terminals 110 have 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 arranged separately from each other in the X-axis direction.

[0049] The casing 120 has a rectangular parallelepiped shape and presents the appearance of the battery 100. The casing 120 includes a casing main body 120A that houses an electrode body and an electrolytic solution not shown, and a sealing plate 120B that seals the opening of the casing main body 120A. The sealing plate 120B is joined to the casing main body 120A by welding.

[0050] The casing 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.

[0051] 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.

[0052] Each of the first side surface 123 and the second side surface 124 is formed by 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 multiple side surfaces of the casing 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 with the X-axis direction as the long side direction and the Z-axis direction as the short side direction when viewed in the Y-axis direction.

[0053] A plurality of batteries 100 are stacked in such a manner that the first side surfaces 123 face each other and the second side surfaces 124 face each other between the batteries 100 and 100 adjacent in the Y-axis direction. Thus, 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 alternately arranged.

[0054] The gas discharge valve 130 is provided on the upper surface 121. When the gas generated inside the casing 120 due to the temperature rise (thermal runaway) of the battery cell 100 causes the internal pressure of the casing 120 to become equal to or higher than a specified value, the gas discharge valve 130 discharges the gas to the outside of the casing 120.

[0055] Figure 3 、 Figure 4 is the front view of the separator 200. Figure 4 The shown separator 200 isFigure 3 A modified example of the partition plate 200 shown. As Figure 3 and Figure 4 shown, the partition plate 200 includes a base portion 210 and a protrusion portion 220 that protrudes from the base portion 210 in the Y-axis direction.

[0056] The partition plate 200 can be made of a material having electrical insulation and elasticity. The partition plate 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 partition plate 200 is preferably made of silicone rubber or fluororubber.

[0057] The hardness (Shore A hardness) of the material constituting the partition plate 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.

[0058] The partition plate 200 according to the present embodiment has a feature in the shape and arrangement of the protrusion portion 220. Hereinafter, the form of the protrusion portion 220 will be described.

[0059] Figure 5 FIG. is a view showing a protrusion portion 221 as an example of the protrusion portion provided on the partition plate 200, Figure 6 is a cross-sectional view of the protrusion portion 221, Figure 7 is a cross-sectional view showing the state where the protrusion portion 221 is compressed. In addition, Figure 8 is a view showing the relationship between the compression amount and the reaction force of the protrusion portion 221.

[0060] As Figure 5 shown, the protrusion portion 221 has a substantially rectangular shape when viewed from the Y-axis direction, but the shape of the protrusion portion is not limited thereto. As Figure 6 , Figure 7 shown, the protrusion portion 221 has a cross-sectional shape that is symmetric about a central axis 221A (first axis) extending in the Y-axis direction.

[0061] If a compressive force in the Y-axis direction is applied to the protrusion portion 221 from the state shown in Figure 6 , then as Figure 7 shown, the protrusion portion 221 is compressed while keeping the central axis 221A in a straight shape. At this time, as Figure 8 shown, as the compression amount of the protrusion portion 221 increases, its reaction force also increases.

[0062] Figure 9 FIG. is a view showing a protrusion portion 222 as another example of the protrusion portion provided on the partition plate 200, Figure 10 is a cross-sectional view of the protrusion portion 222, Figure 11It is a cross-sectional view showing the state where the protrusion 222 is compressed. Figure 12 It is a graph showing the relationship between the amount of compression of the protrusion 222 and the reaction force.

[0063] As Figure 9 shown, the protrusion 222 has a substantially rectangular shape when viewed from the Y-axis direction. As Figure 10 、 Figure 11 shown, the protrusion 222 includes: a main body portion 222B (first portion) having a cross-sectional shape symmetric about a central axis 222A (first axis) extending in the Y-axis direction; and an asymmetric portion 222C (second portion) that further protrudes from a part of the end in the Y-axis direction and has a shape asymmetric about the central axis 222A.

[0064] 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.

[0065] If a compressive force in the Y-axis direction is applied to the protrusion 222 from the state shown in Figure 10 and this compressive force exceeds a specified magnitude, then as Figure 11 shown, the central axis 222A of the protrusion 222 is bent and deformed. That is, if a compressive force exceeding a specified magnitude acts on the protrusion 222, the columnar protrusion 222 buckles. As Figure 12 shown, in the region exceeding the buckling load, the amount of compression increases with a small load.

[0066] In the protrusion 220 of the separator 200 according to the present embodiment, by mixing the above-mentioned protrusions 221 and 222, the required minimum compressive reaction force can be ensured, and at the same time, an excessive increase in the reaction force acting on the battery 100 due to an increase in the amount of compression of the separator 200 can be suppressed.

[0067] Regarding the arrangement and shape of the protrusions 221 and 222 in the separator 200, they can be appropriately changed.

[0068] Figures 13 to 18 It is a cross-sectional view showing a modified example of the protrusion 222. As Figure 13 shown, the asymmetric portion 222C may also be a shape that protrudes conically 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.

[0069] As Figure 14 、 Figure 15 shown, the asymmetric portion 222C may also be a shape that protrudes conically 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.

[0070] The asymmetric portion 222C can be formed only on one side in the X-axis direction with respect to the main body portion 222B ( Figure 14 ), or can be formed on both sides in the X-axis direction with respect to the main body portion 222B ( Figure 15 ). The asymmetric portion 222C can be formed over the entire Y-axis direction ( Figure 14 ), or can be formed on a part of the Y-axis direction ( Figure 15 ).

[0071] In the case where the cross-sectional shape of the asymmetric portion 222C is a rectangular shape, it is not limited to the example of Figure 10 , and it can also be a shape such as Figure 16 , Figure 17 illustrated. In addition, as shown in Figure 18 , when viewed from the Y-axis direction, the asymmetric portion 222C can also be formed by forming a concave portion 222D that opens in the X-axis direction in a part of the columnar protrusion portion 222. The concave portion 222D can also open in the Z-axis direction. At this time, as shown by the arrow in Figure 18 , deformation in the direction of closing the opening of the concave portion 222D can be promoted.

[0072] Figures 19 to 22 is a front view showing other modified examples of the partition plate 200, and shows modified examples of the arrangement of the protrusion portions 220 in the partition plate 200, respectively.

[0073] As in the example of Figure 19 , the shape of the protrusion portion 220 can also be a shape obtained by combining a rectangular shape and a conical shape. As in the example of Figure 20 , the protrusion portion 220 can also be a shape that is slender when viewed from the Y-axis direction. In the example of Figure 20 , the Z-axis direction is the long side direction and the X-axis direction is the short side direction, but it can also be the opposite, and the long side direction can also be an inclined direction (a direction that intersects both the X-axis direction and the Z-axis direction).

[0074] As in the example of Figure 21 , the protrusion portion 220 can also have a shape in which a hole portion 223 is provided inside a rectangular shape. The hole portion 223 can be single or multiple. The number and arrangement of the hole portions 223 can be appropriately changed. In addition, as in the example of Figure 22 , a concave portion 224 can also be provided on a part of the outer edge of the hole portion 223.

[0075] In the example of Figure 22 , the periphery of the hole portion 223 in which the concave portion 224 is formed is likely to be deformed, and this part is likely to be buckled. That is, in Figure 22In the example, the portion around the recess 224 constitutes the "asymmetric portion" of the protrusion 220.

[0076] Figures 23A to 23C FIG. is a view showing a state in which the protrusions 221 and 222 are compressed while being in contact with each other. As Figure 23A shown, the protrusion 221 without an asymmetric portion and the protrusion 222 with an asymmetric portion are adjacently provided at a distance below the height of the protrusion. If Figure 23A from the state shown, a compressive force is applied to the protrusion 220, then as Figure 23B shown, the protrusion 221 is compressed while remaining substantially vertically erected. On the other hand, the protrusion 222 is compressed while being bent and inclined toward the protrusion 221. If Figure 23B from the state shown, the compressive force applied to the protrusion 220 is further increased, then as Figure 23C shown, the bent and inclined protrusion 222 comes into contact with the protrusion 221, and the protrusion 222 pushes down the protrusion 221 while the compression progresses. By setting it in this way, it is possible to suppress an excessive increase in the reaction force applied to the battery 100 when the compression amount of the separator 200 increases.

[0077] At this time, the protrusion 221 that does not come into contact with the protrusion 222 even when the protrusion 222 is bent can be provided on the separator 200 facing the peripheral portion of the battery 100. Since the protrusion 221 of this portion is not bent even when the protrusion 222 is bent, the distance from the adjacent battery 100 can be ensured.

[0078] Figure 24A And Figure 24B FIG. is a view schematically showing an apparatus for obtaining the relationship between the compression rate and the load of the separator 200. Figure 25 FIG. is a view showing the relationship between the compression rate and the load of the separator 200.

[0079] As Figure 24A And Figure 24B shown, the separator 200 is compressed using the jig 300, and the relationship between the load F (reaction force) and the compression rate at this time is obtained. The compression rate is obtained by the following formula.

[0080] Compression rate = (L0 - L) / L0

[0081] As Figure 25 shown, the slope of the compression rate - load curve until the compression rate becomes 0.2 (20%) is defined as the "elastic constant" of the separator 200. The "elastic constant" of the separator 200 according to the present embodiment is preferably about 1 MPa or more and 10 MPa or less.

[0082] The above describes the embodiments of the present invention, but it should be considered that the disclosed embodiments are illustrative rather than restrictive in all aspects. The scope of the present invention is represented by the claims and is intended to include the equivalent meaning of the claims and all modifications within the scope.

Claims

1. A separator, which is disposed between a plurality of batteries arranged in a first direction or between a battery and an end plate, wherein, the above-mentioned separator comprises: a base portion; and a protrusion portion that protrudes from the above-mentioned base portion in the above-mentioned first direction, the above-mentioned protrusion portion includes a first portion and a second portion integrally formed, the above-mentioned first portion has a shape symmetric about a first axis extending in the above-mentioned first direction, the above-mentioned second portion has a shape asymmetric about the above-mentioned first axis, in the above-mentioned protrusion portion, the volume of the above-mentioned first portion is larger than the volume of the above-mentioned second portion.

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

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

4. The separator according to any one of claims 1 to 3, wherein, the above-mentioned second portion is formed throughout the entire cross-section of the above-mentioned protrusion portion in the above-mentioned first direction.

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

6. A battery pack, wherein, the above-mentioned battery pack comprises: a plurality of batteries arranged in a first direction; and the separator according to any one of claims 1 to 3, which is disposed between the above-mentioned plurality of batteries.

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