battery pack

Abstract

A battery pack is provided that provides thermal insulation between adjacent batteries, suppresses unintended effects on adjacent batteries during thermal runaway, and reduces the overall size of the battery pack. [Solution] The separator includes a first layer having a melting point of 950°C or higher and 2715°C or lower, a second layer having a thermal conductivity of 0.02 W / m·K or higher and 0.15 W / m·K or lower in an environment at a temperature of 700°C and a pressure of 0.2 MPa, and a third layer in which the compressive load acting on a rectangular test piece having dimensions of 50 mm square when viewed from a first direction is 0.7 kN or higher when the thickness is 5 mm and 8 kN or lower when the thickness is 2.5 mm, and the first, second, and third layers are arranged so as to be aligned in the first direction.

Description

[Technical Field]

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

[0002] 2. Description of the Related Art In a battery pack in which a plurality of batteries are stacked, it has been common practice to interpose a member having the function of suppressing heat transfer or cushioning surface pressure between adjacent batteries.

[0003] Examples of conventional devices include those described in Japanese Patent Laid-Open No. 2020-165483 (Patent Document 1) and Japanese Patent Laid-Open No. 2007-165698 (Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-165483 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-165698 Summary of the Invention [Problem to be solved by the invention]

[0005] In battery packs, it is necessary to ensure thermal insulation between adjacent batteries. It is also necessary to prevent unintended effects on adjacent batteries when thermal runaway occurs in one battery that constitutes the battery pack. From a different perspective, it is also necessary to reduce the size of the battery pack.

[0006] From the viewpoint of meeting these demands, there is still room for improvement in conventional battery packs.

[0007] The objective of this technology is to provide a battery pack that provides thermal insulation between adjacent batteries, suppresses unintended effects on adjacent batteries in the event of thermal runaway, and reduces the overall size of the battery pack. [Means for solving the problem]

[0008] The present technology provides the following assembled battery.

[0009] [1] An assembled battery comprising: a plurality of batteries arranged in a first direction; and separators provided between the plurality of batteries, wherein the separators include a first layer having a melting point of 950°C or higher and 2715°C or lower; a second layer having a thermal conductivity of 0.02 W / m·K or higher and 0.15 W / m·K or lower in an environment at a temperature of 700°C and a pressure of 0.2 MPa; and a third layer such that a compressive load acting on a rectangular test piece having dimensions of 50 mm square when viewed from the first direction is 0.7 kN or higher at a thickness of 5 mm and 8 kN or lower at a thickness of 2.5 mm, and the first layer, second layer, and third layer are arranged so as to be aligned in the first direction.

[0010] [2] The battery pack according to [1], wherein the first layer includes a portion having a wave shape or a curved shape.

[0011] [3] The battery pack according to [1] or [2], wherein the first layer is disposed so as to be sandwiched between the second layer and the third layer in the first direction.

[0012] [4] An assembled battery comprising: a plurality of batteries arranged in a first direction; and separators arranged between the plurality of batteries, wherein the separators comprise a first layer having a melting point of 950°C or higher and 2000°C or lower; and a second layer having a thermal conductivity of 0.02 W / m·K or higher and 0.15 W / m·K or lower in an environment at a temperature of 700°C and a pressure of 0.2 MPa; the first layer includes a portion having a corrugated or curved shape; and the first layer and the second layer are arranged so as to be aligned in the first direction.

[0013] [5] The battery pack according to any one of [1] to [4], wherein the first layer is made of metal, ceramic, or glass.

[0014] [6] The battery pack according to any one of [1] to [5], wherein the first layer has a thickness of 0.3 mm or more and 2.0 mm or less. [Effects of the Invention]

[0015] According to the present technology, it is possible to provide a battery pack that provides thermal insulation between adjacent batteries, suppresses unintended effects on adjacent batteries in the event of thermal runaway, and reduces the overall size of the battery pack. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 2 is a perspective view showing a battery pack. [Figure 2] FIG. [Figure 3] FIG. 1 is a cross-sectional view of a separator (part 1). [Figure 4] FIG. 2 is a cross-sectional view of the separator (part 2). [Figure 5] FIG. 3 is a cross-sectional view of the separator (part 3). [Figure 6] FIG. 4 is a cross-sectional view of the separator. [Figure 7] FIG. 5 is a cross-sectional view of the separator. [Figure 8] FIG. 6 is a cross-sectional view of the separator. [Figure 9] FIG. 7 is a cross-sectional view of the separator. [Figure 10] FIG. 8 is a cross-sectional view of the separator. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present technology will be described. Note that the same or corresponding parts are denoted by the same reference characters, and description thereof may not be repeated.

[0018] In the embodiments described below, when numbers, amounts, etc. are mentioned, the scope of the present technology is not necessarily limited to those numbers, amounts, etc., unless otherwise specified. Furthermore, in the following embodiments, each component is not necessarily essential to the present technology, unless otherwise specified. Furthermore, the present technology is not necessarily limited to those that achieve all of the effects and advantages mentioned in the present embodiments.

[0019] In this specification, the terms "comprise," "include," and "have" are open-ended. That is, when a certain feature is included, other features may or may not be included.

[0020] Furthermore, when geometric terms and terms expressing positional and directional relationships are used in this specification, such as "parallel," "orthogonal," "45° diagonal," "coaxial," and "along," these terms allow for manufacturing errors and slight variations. When terms expressing relative positional relationships, such as "upper side" and "lower side," are used in this specification, these terms are used to indicate relative positional relationships in a single state, and the relative positional relationships can be reversed or rotated to any angle depending on the installation direction of each mechanism (for example, by turning the entire mechanism upside down).

[0021] In this specification, the term "battery" is not limited to lithium-ion batteries, but may include other batteries such as nickel-metal hydride batteries and sodium-ion batteries. In this specification, the term "electrode" may collectively refer to a positive electrode and a negative electrode.

[0022] In this specification, a "battery" can be installed in a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), an electric vehicle (BEV), etc. However, the use of a "battery" is not limited to being installed in a vehicle.

[0023] Fig. 1 is a perspective view showing a battery pack. As shown in Fig. 1, the battery pack 1 includes batteries 100, separators 200, and end plates 300. The batteries 100 and separators 200 are arranged alternately along the Y-axis direction (first direction). The end plates 300 are provided at both ends in the Y-axis direction.

[0024] The batteries 100 are rectangular batteries, and a plurality of batteries 100 are provided along the Y-axis direction. The plurality of batteries 100 are electrically connected to each other via bus bars (not shown).

[0025] Separators 200 are provided between multiple batteries 100. The separators 200 are insulating members that prevent unintended electrical conduction between adjacent batteries 100. The separators 200 ensure electrical insulation between adjacent batteries 100. Separators 200 are also provided between the batteries 100 and the end plates 300.

[0026] The end plates 300 provided at both ends in the Y-axis direction are connected to each other by restraining members (not shown). At this time, the stack of multiple batteries 100 and separators 200 is held in a compressed state in the Y-axis direction by the end plates 300. As a reaction, a reaction force from the batteries 100 acts on the end plates 300, and a tensile stress in the Y-axis direction is generated in the restraining members.

[0027] 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, a gas release valve 130, and a liquid injection hole 140.

[0028] The electrode terminal 110 is formed on the housing 120. The electrode terminal 110 has a positive electrode terminal 111 and a negative electrode terminal 112 that are aligned along the X-axis direction (second direction) that is perpendicular to the Y-axis direction. The positive electrode terminal 111 and the negative electrode terminal 112 are spaced apart from each other in the X-axis direction.

[0029] The housing 120 has a rectangular parallelepiped shape and forms the external appearance of the battery 100. The housing 120 includes a case body 120A that contains electrode assemblies (for example, the three electrode assemblies 180 illustrated in FIG. 4) and an electrolyte, 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.

[0030] 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. The upper surface 121, the lower surface 122, the first side surface 123, the second side surface 124, and the third side surface 125 each have a rectangular shape.

[0031] The upper surface 121 is a plane perpendicular to the Z-axis direction (third direction) that is perpendicular to the Y-axis direction and the X-axis direction. The electrode terminals 110 are disposed on the upper surface 121. The lower surface 122 faces the upper surface 121 along the Z-axis direction.

[0032] Each of the first side surface 123 and the second side surface 124 is made of a plane perpendicular 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 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 when viewed in the Y-axis direction, with the X-axis direction being the longitudinal direction and the Z-axis direction being the lateral direction.

[0033] The multiple batteries 100 are stacked such that the first side surfaces 123 and the second side surfaces 124 of the batteries 100 adjacent to each other in the Y-axis direction face each other. As a result, the positive electrode terminals 111 and the negative electrode terminals 112 are arranged alternately in the Y-axis direction in which the multiple batteries 100 are stacked.

[0034] Case body 120A and sealing plate 120B are made of metal, specifically aluminum, aluminum alloy, iron, iron alloy, or the like.

[0035] The case body 120A is formed so that it is longer in the width direction (X-axis direction) of the battery 100 than in the thickness direction (Y-axis direction) and height direction (Z-axis direction) of the battery 100. That is, when the battery 100 is viewed from the Y-axis direction, the housing 120 (case) of the battery 100 has a substantially rectangular shape with the X-axis direction (second direction) as the longitudinal direction and the Z-axis direction (third direction) as the lateral direction.

[0036] Gas release valve 130 is provided on top surface 121. When the temperature of battery 100 rises (thermal runaway) and the internal pressure of housing 120 exceeds a predetermined value due to gas generated inside housing 120, gas release valve 130 releases the gas to the outside of housing 120.

[0037] The liquid inlet 140 is provided on the top surface 121. The electrolyte is injected into the housing 120 through the liquid inlet 140. The liquid inlet 140 is sealed with a sealing member. For example, a blind rivet or other metal member can be used as the sealing member.

[0038] The positions of the gas exhaust valve 130 and the liquid injection hole 140 are not limited to those shown in FIG. 2, and can be changed as appropriate.

[0039] Next, the structure of the separator 200 will be described with reference to Figures 3 to 10. Figures 3 to 10 are cross-sectional views of the separator 200 as viewed from the X-axis direction.

[0040] 3, the separator 200 includes a first layer 210, a second layer 220, and a third layer 230. The first layer 210, the second layer 220, and the third layer 230 are arranged to be aligned in the Y-axis direction. The first layer 210 is disposed so as to be sandwiched between the second layer 220 and the third layer 230.

[0041] The melting point of first layer 210 is about 950°C or higher (preferably about 1000°C or higher, and more preferably about 1200°C or higher). The melting point of first layer 210 is preferably about 2715°C or lower, and more preferably about 2000°C or lower. First layer 210 is preferably made of metal, ceramic, or glass.

[0042] Examples of metals having a melting point of about 950°C or higher include gold (1064°C), silver (962°C), titanium (1668°C), copper (1085°C), nickel (1455°C), and stainless steel (about 1400 to 1500°C).

[0043] Examples of ceramics having a melting point of 950°C or higher include alumina (approximately 2050°C to 2070°C) and zirconia (2715°C). Examples of glasses having a melting point of 950°C or higher include magnesium fluoride glass (1255°C).

[0044] For example, if the housing 120 of the battery 100 is made of aluminum, the melting point of aluminum is approximately 660°C, and therefore the melting point of the first layer 210 (950°C or higher) is higher than the melting point of the housing 120. Furthermore, the thickness of the first layer 210 is preferably approximately 0.3 mm or more and 2.0 mm or less.

[0045] Second layer 220 has a thermal conductivity of approximately 0.02 W / m·K or more and 0.15 W / m·K or less in a high-temperature, high-pressure environment of a temperature of 700°C and a pressure of 0.2 MPa. Second layer 220 can be formed from, for example, nanosilica, glass fiber, nonwoven fabric, etc. The thickness of second layer 220 is preferably approximately 3 mm or less.

[0046] The third layer 230 has the function of absorbing an increase in the reaction force from the battery 100 when the battery 100 expands. A rectangular test piece measuring 50 mm square when viewed from the Y-axis direction is cut out of the material constituting the third layer 230, and a compressive load is applied to the test piece. At this time, the thickness of the test piece and the compressive load acting on the test piece are measured simultaneously. It is preferable that the measurement results show that the compressive load is approximately 0.7 kN or more when the thickness is 5 mm, and the compressive load is 8 kN or less when the thickness is 2.5 mm. The third layer 230 can be formed from an elastic material such as rubber (EPDM), silicone, foam rubber, or foam silicone.

[0047] When thermal runaway occurs in one of the batteries 100 that make up the battery pack 1, it is necessary to prevent unintended effects on adjacent batteries 100. This point is evaluated in a performance test of the battery pack.

[0048] For example, in an evaluation test of a battery pack including the battery pack 1, a specific battery 100 (trigger cell) in the battery pack 1 may be forced to go into thermal runaway, and the subsequent behavior of the battery pack as a whole (whether or not spreading of fire can be prevented, etc.) may be evaluated. Specifically, the trigger cell may be forced to short-circuit by inserting a nail, heated by a heater, or the like.

[0049] Examples of standards for the above evaluation tests include those specified in the United Nations Convention Regulation "UN ECE-R100," China's "National Standard (GB)," and Japan Industrial Standards' "JIS C 8715."

[0050] The separator 200 according to this embodiment is provided with a first layer 210 having a melting point of approximately 950°C or higher and 2715°C or lower, so that even when thermal runaway occurs in one of the batteries 100 constituting the battery pack 1, melting of the first layer 210 provided between the adjacent batteries 100 can be suppressed or delayed. Therefore, the batteries 100 adjacent to the battery 100 in which thermal runaway has occurred can be protected. The first layer 210 functions as a heat-resistant layer when thermal runaway occurs.

[0051] In separator 200 according to this embodiment, second layer 220 having a thermal conductivity of approximately 0.02 W / m·K or more and 0.15 W / m·K or less (under an environment of a temperature of 700°C and a pressure of 0.2 MPa) is provided, thereby ensuring thermal insulation between adjacent batteries 100 in a temperature range that does not lead to thermal runaway. Furthermore, if second layer 220 has a melting point similar to that of first layer 210, even during thermal runaway, second layer 220 can cooperate with first layer 210 to function to protect batteries 100 adjacent to the battery 100 experiencing thermal runaway.

[0052] In separator 200 according to this embodiment, third layer 230 made of an elastic material with a predetermined deformation absorption property is provided, and therefore, even when casing 120 expands during use of battery 100, an increase in reaction force from battery 100 can be absorbed. Therefore, a mechanism for absorbing reaction force can be built into separator 200, and the battery pack 1 as a whole can be made smaller and more space-saving in the Y-axis direction.

[0053] In this manner, with the separator 200 according to the present embodiment, the first layer 210, the second layer 220, and the third layer 230 work together to provide thermal insulation between the batteries 100, suppress unintended effects on adjacent batteries 100 during thermal runaway, and reduce the size of the entire battery pack 1.

[0054] 3, the first layer 210 is arranged so as to be sandwiched between the second layer 220 and the third layer 230, but the scope of the present technology is not limited thereto, and for example, as shown in Fig. 4, the second layer 220 may be arranged so as to be sandwiched between the first layer 210 and the third layer 230, or as shown in Fig. 5, the third layer 230 may be arranged so as to be sandwiched between the first layer 210 and the second layer 220. Furthermore, as shown in Fig. 6, the second layer 220 and the third layer 230 may be arranged so as to be sandwiched between two first layers 210.

[0055] When the first layer 210 is disposed in a position where it contacts the battery 100, as in the examples of FIGS. 4 to 6, the first layer 210 is configured so that at least the surface thereof has insulating properties.

[0056] 7 to 10 are characterized in that the first layer 210 includes a portion having a wavy shape (FIGS. 7, 9, and 10) or a curved shape (FIG. 8). Note that the wavy and curved shapes are not limited to those shown in FIGS. 7 to 10.

[0057] 7 to 10, the corrugated or curved portions of the first layer 210 elastically deform, thereby absorbing an increase in the reaction force from the battery 100. As in the examples of Figures 7 to 9, the corrugated or curved portions may be used in combination with the third layer 230, or, if the function of the third layer 230 can be substituted by providing the first layer 210 with a corrugated portion (or curved portion), the separator 200 may be formed of only the first layer 210 and the second layer 220, as in the example of Figure 10.

[0058] In the present embodiment, the gas release valve 130, the liquid inlet 140, and the electrode terminal 110 are arranged on the same surface of the housing 120, but the scope of the present technology is not limited thereto, and the gas release valve 130, the liquid inlet 140, and the electrode terminal 110 may be arranged on different surfaces of the housing 120. Furthermore, the electrode terminal 110 may be arranged on a surface other than the top surface 121, and the positive electrode terminal 111 and the negative electrode terminal 112 may be arranged on different surfaces of the housing 120.

[0059] Although the embodiments of the present technology have been described above, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present technology is defined by the claims, and it is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0060] 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 release valve, 140 liquid injection hole, 180 electrode body, 200 separator, 210 first layer, 220 second layer, 230 third layer, 300 end plate.

Claims

1. a plurality of batteries arranged in a first direction; a separator disposed between the plurality of batteries; The separator is a first layer having a melting point of 950°C or higher and 2715°C or lower; a second layer having a thermal conductivity of 0.02 W / m·K or more and 0.15 W / m·K or less in an environment of a temperature of 700°C and a pressure of 0.2 MPa; a third layer in which a compressive load acting on a rectangular test piece having dimensions of 50 mm square when viewed from the first direction is 0.7 kN or more when the thickness is 5 mm and 8 kN or less when the thickness is 2.5 mm; The battery pack, wherein the first layer, the second layer, and the third layer are arranged side by side in the first direction.

2. The battery pack according to claim 1 , wherein the first layer includes a portion having a wave-shaped or curved shape.

3. 3. The battery pack according to claim 1, wherein the first layer is disposed so as to be sandwiched between the second layer and the third layer in the first direction.

4. a plurality of batteries arranged in a first direction; a separator disposed between the plurality of batteries; The separator is a first layer having a melting point of 950°C or higher and 2000°C or lower; a second layer having a thermal conductivity of 0.02 W / m·K or more and 0.15 W / m·K or less in an environment of a temperature of 700°C and a pressure of 0.2 MPa; the first layer includes a portion having a wave-shaped or curved shape; The battery pack, wherein the first layer and the second layer are arranged side by side in the first direction.

5. 5. The battery pack according to claim 1, wherein the first layer is made of metal, ceramic, or glass.

6. 5. The battery pack according to claim 1, wherein the first layer has a thickness of 0.3 mm or more and 2.0 mm or less.

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