Battery pack

Abstract

The invention relates to a battery pack. An insulating member (200) provided between a plurality of batteries (100) includes a first portion (211, 210) and a second portion (212, 220) arranged in a first direction, the first portion (211, 210) being provided in a first region including a region of a case (120) of the plurality of batteries (100) when viewed from the first direction, the second portion (212, 220) being provided in a second region formed further inward than the region of the case (120) of the plurality of batteries (100) when viewed from the first direction, and the first portion (211, 210) being provided in a second region formed further inward than the region of the case (120) of the plurality of batteries (100) when viewed from the first direction. The second portion (212, 220) is in contact with at least one battery (100) among the plurality of batteries (100) positioned on both sides of the insulating member (200), and the heat insulation property of the first portion (211, 210) is greater than or equal to the heat insulation property of the second portion (212, 220).

Description

TECHNICAL FIELD

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

[0002] In the past, in a battery pack in which a plurality of batteries are arranged, an insulating member is disposed between the plurality of batteries. As a conventional battery pack, for example, a battery pack described in Japanese Patent Application Publication No. 2022-149419 (JP 2022-149419 A) can be cited.

[0003] It is required to prevent heat from spreading (heat spread) between adjacent batteries by disposing an insulating member. In addition, it is also required to stably hold a plurality of batteries. From the viewpoint of giving consideration to both prevention of heat spread and holding of batteries, there is still room for improvement for the conventional battery pack. SUMMARY

[0004] An object of the present technology is to provide a battery pack that gives consideration to both prevention of heat spread and holding of batteries.

[0005] The present technology provides the following battery pack. [1]

[0007] A battery pack includes a plurality of batteries arranged in a first direction, each of the plurality of batteries including a case that houses an electrode body; and an insulating member disposed between the plurality of batteries, the insulating member including a first portion and a second portion arranged in the first direction, the first portion being disposed in a first region including a region of the case of the plurality of batteries when viewed in the first direction, the second portion being disposed in a second region formed inward of the region of the case of the plurality of batteries when viewed in the first direction, the second portion abutting against at least one of the plurality of batteries on a side of the insulating member, and a thermal insulation property of the first portion being equal to or higher than a thermal insulation property of the second portion. [2]

[0009] In the battery pack described in [1], the first portion and the second portion are composed of the same raw material. [3]

[0011] In the battery pack described in [1], the thermal insulation property of the first portion is higher than the thermal insulation property of the second portion. [4]

[0013] In the battery pack described in [1], the second portion has a lower elastic modulus than the first portion. [5]

[0015] The battery pack according to any one of [1] to [4], in which the elastic coefficient of the insulating member is 1 MPa or more and 10 MPa or less, when the slope of the compression rate-load curve until the compression rate of the insulating member becomes 20% is determined as the elastic coefficient of the insulating member. [6]

[0017] The battery pack according to any one of [1] to [5], in which the thermal conductivity of the first portion is 0.15 W / mK or less. [7]

[0019] The battery pack according to any one of [1] to [6], in which the thickness of the insulating member in the first direction is 20 mm or less.

[0020] The above and other objects, features, aspects and advantages of the present application will become more apparent from the following detailed description of the present application when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a perspective view showing a battery pack.

[0022] Figure 2 is a perspective view showing a battery constituting the battery pack.

[0023] Figure 3 is a view showing the structure of an insulating member (separator) according to Embodiment (1).

[0024] Figure 4 is a view showing the structure of an insulating member (separator) according to Embodiment (2).

[0025] Figure 5 is a view (1) for explaining the distribution of load acting on a secondary battery.

[0026] Figure 6 is a view (2) for explaining the distribution of load acting on a secondary battery.

[0027] Figure 7 is a view schematically showing an apparatus for finding the relationship between the compression rate and load of a separator.

[0028] Figure 8 is a view showing the relationship between the compression rate and load of a separator. DETAILED DESCRIPTION

[0029] Hereinafter, an embodiment of the present technology will be described. Furthermore, the same reference numerals are sometimes attached to the same or equivalent portions, and the description thereof is not repeated.

[0030] Further, in the embodiments described below, in the case where a number, an amount, and the like are mentioned, unless otherwise specifically described, the scope of the present technology is not necessarily limited to the number, the amount, and the like. Further, in the embodiments described below, unless otherwise specifically described, each of the constituent elements is not necessarily essential for the present technology. Further, the present technology is not limited to necessarily exert all the functional effects mentioned in the present embodiments.

[0031] Further, in the present specification, the description of "comprise" and "include" and "have" is in an open form. That is, in the case of including a certain structure, other structures can be further included, or can not be included.

[0032] Further, in the present specification, in the case where a geometrical term and a term indicating a positional relationship, a directional relationship, such as "parallel", "orthogonal", "oblique by 45°", "coaxial", "along", and the like are used, these terms allow a manufacturing error or a certain variation. In the case where a term indicating a relative positional relationship, such as "upper side", "lower side", and the like is used in the present specification, these terms are used as terms indicating a relative positional relationship in one state, and the relative positional relationship can be reversed or rotated to an arbitrary angle depending on the setting direction of each mechanism (for example, reversing the entire mechanism upside down, or the like).

[0033] In the present specification, "battery" is not limited to a lithium-ion battery, and can include a nickel-hydrogen battery, a sodium-ion battery, and other batteries. In the present specification, the positive electrode and the negative electrode can be collectively referred to as "electrode".

[0034] The "battery" in the present specification can be mounted on a hybrid vehicle (HEV: Hybrid Electric Vehicle), a plug-in hybrid vehicle (PHEV: Plug-in Hybrid Electric Vehicle), an electric vehicle (BEV: Battery Electric Vehicle), and the like. However, the use of the "battery" is not limited to vehicle-mounted use.

[0035] Figure 1 is a perspective view of a battery module to which the present embodiment is applied. As shown in Figure 1 , the battery pack 1 includes a battery 100 and a separator 200. The battery 100 and the separator 200 are alternately arranged in the Y-axis direction (first direction). The arranged battery 100 and the separator 200 are held by restraining them in the Y-axis direction using a restraining member (a band and an end plate) and a battery pack case, which are not shown.

[0036] The battery 100 is a square battery, and a plurality of batteries 100 are provided in the Y-axis direction. The plurality of batteries 100 are electrically connected to each other via a bus bar, which is not shown.

[0037] A separator 200 is provided between the plurality of batteries 100. The separator 200 is an insulating member that prevents the adjacent batteries 100 from being electrically conducted by accident. The separator 200 ensures the electrical insulation of the adjacent batteries 100. The separator 200 can also be provided between the battery 100 and an end plate not shown.

[0038] Figure 2 is a perspective view of the battery 100. As shown in Figure 2 , the battery 100 has a square shape. The battery 100 has an electrode terminal 110, a case 120, and an exhaust valve 130.

[0039] The electrode terminal 110 is formed on the case 120. The electrode terminal 110 has a positive electrode terminal 111 and a negative electrode terminal 112 arranged along an X-axis direction (2nd direction) orthogonal to a Y-axis direction (1st direction). The positive electrode terminal 111 and the negative electrode terminal 112 are disposed apart from each other in the X-axis direction.

[0040] The case 120 has a rectangular parallelepiped shape, and forms the appearance of the battery 100. The case 120 includes a case main body 120A that houses an electrode body and an electrolyte solution not shown, and a sealing plate 120B that seals an opening of the case main body 120A. The sealing plate 120B is joined to the case main body 120A by welding.

[0041] The case 120 has an upper surface 121, a lower surface 122, a 1st side surface 123, a 2nd side surface 124, and two 3rd side surfaces 125.

[0042] The upper surface 121 is a plane orthogonal to a Z-axis direction (3rd direction) orthogonal to the Y-axis direction and the X-axis direction. The electrode terminal 110 is disposed on the upper surface 121. The lower surface 122 is opposite to the upper surface 121 along the Z-axis direction.

[0043] Each of the 1st side surface 123 and the 2nd side surface 124 is constituted by a plane orthogonal to the Y-axis direction. Each of the 1st side surface 123 and the 2nd side surface 124 has the largest area among the plurality of side surfaces of the case 120. Each of the 1st side surface 123 and the 2nd side surface 124 has a rectangular shape when viewed in the Y-axis direction. Each of the 1st side surface 123 and the 2nd side surface 124 has a rectangular shape in which the X-axis direction becomes a long side direction and the Z-axis direction becomes a short side direction when viewed in the Y-axis direction.

[0044] The plurality of batteries 100 are stacked in a manner that the 1st side surfaces 123 face each other and the 2nd side surfaces 124 face each other between the batteries 100, 100 adjacent in the Y-axis direction. Thus, the positive electrode terminals 111 and the negative electrode terminals 112 are alternately arranged in the Y-axis direction in which the plurality of batteries 100 are stacked.

[0045] An exhaust valve 130 is provided to the upper surface 121. The exhaust valve 130 exhausts gas to the outside of the case 120 in a case where the temperature of the battery 100 rises (thermal runaway) so that the internal pressure of the case 120 becomes a prescribed value or more due to the gas generated in the inside of the case 120.

[0046] Figure 3 is a view that shows the structure of the separator 200 (insulating member) according to one embodiment.

[0047] As shown in Figure 3 , the separator 200 is configured by a thermal insulating member 210. The thermal insulating member 210 includes a first portion 211 and a second portion 212. In the example shown in Figure 3 , the first portion 211 and the second portion 212 are configured by a single member, and are configured by the same raw material. Therefore, the thermal insulating properties of the first portion 211 and the second portion 212 are the same as each other.

[0048] The first portion 211 and the second portion 212 are provided in a manner of being arranged in the Y-axis direction. In the example shown in Figure 3 , the second portion 212 is formed on both sides of the first portion 211 in the Y-axis direction. The second portion 212 abuts against the two batteries 100 located on both sides of the separator 200, respectively. However, the second portion 212 can be provided on only one side of the first portion 211 in the Y-axis direction.

[0049] In the example shown in Figure 3 , a region (first region) in which the first portion 211 is provided is the same as the region of the case 120 when viewed in the Y-axis direction. However, the first portion 211 can be provided in a region including the region of the case 120, or in a range wider than the region of the case 120. In addition, a region (second region) in which the second portion 212 is provided is formed inside the case 120 of the battery 100 when viewed in the Y-axis direction.

[0050] Figure 4 is a view that shows the structure of the separator 200 (insulating member) according to another embodiment.

[0051] In the example shown in Figure 4 , the separator 200 includes a thermal insulating member 210 (first portion) and an elastic body 220 (second portion). The thermal insulating member 210 and the elastic body 220 are configured by different members, and are configured by different raw materials. Specifically, the thermal insulating property of the thermal insulating member 210 is higher than the thermal insulating property of the elastic body 220. In addition, the elastic body 220 is more easily deformed than the thermal insulating member 210. Therefore, the coefficient of elasticity of the elastic body 220 is lower than the thermal insulating member 210.

[0052] The thermal insulator 210 and the elastic body 220 are provided in a manner arranged in the Y-axis direction. In Figure 4 In the example shown, the elastic body 220 is formed on one side of the thermal insulator 210 in the Y-axis direction. The elastic body 220 abuts against the battery 100 on one side of the diaphragm 200. However, the elastic body 220 can also be provided on both sides of the thermal insulator 210 in the Y-axis direction. In addition, the thermal insulator 210 can also be provided on both sides of the elastic body 220.

[0053] In Figure 4 In the example shown, the region in which the thermal insulator 210 is provided (first region) is the same as the region of the case 120 when viewed in the Y-axis direction. However, the thermal insulator 210 can also be provided in a region that includes the outside of the case 120. In addition, the region in which the elastic body 220 is provided (second region) is formed on the inside of the case 120 of the battery 100 when viewed in the Y-axis direction.

[0054] Figure 3 Figure 4 The thermal insulator 210 in the example is preferably composed of a raw material (thermal insulating material) having a prescribed thermal insulating property. As examples of the thermal insulating material, for example, glass wool, asbestos, cellulose fiber, aerogel, and the like can be given. In addition, a mixed molding material of inorganic filler and a binder, a cured material of inorganic fiber and inorganic powder, and a foamed resin containing air in the layer, and the like can also be used.

[0055] The thermal conductivity of the thermal insulator 210 is preferably to the extent of 0.15 W / mK or less, and more preferably to the extent of 0.1 W / mK or less.

[0056] Figure 4 The elastic body 220 in the example is preferably composed of a raw material (elastic body) having a prescribed elasticity. As examples of the elastic body 220, 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, and the like can be given.

[0057] However, in addition to the modulus of elasticity of the elastic body 220, the coefficient of elasticity of the diaphragm 200 as a whole can also be adjusted by the shape of the diaphragm 200.

[0058] The thickness of the diaphragm 200 (gap between the batteries 100) is preferably to the extent of 20 mm or less. In Figure 4 In the laminated structure of the thermal insulator 210 and the elastic body 220 shown, the thermal insulator 210 and the elastic body 220 are each preferably to the extent of 10 mm or less, and each more preferably to the extent of 5 mm or less.

[0059] ​One function of the separator 200 is to prevent heat transfer (heat diffusion) between adjacent batteries 100. Due to the... Figure 3 , Figure 4 In the diaphragm 200 shown, a first portion 211 with constant thermal insulation is provided in a region including at least the area of ​​the housing 120, so that heat conduction caused by radiation or convection at the outer periphery of the housing 120 can be suppressed, and the spread of heat between adjacent batteries 100 can be effectively suppressed.

[0060] Next, use Figure 5 , Figure 6 The distribution of loads (constraint forces) acting on the battery 100 will be explained. In the battery pack 1, multiple batteries 100 are constrained and held in place along the Y-axis direction. Here, it is required that the multiple batteries 100 be held stably. Especially when the battery pack 1 is mounted on a vehicle or other means of transportation, from the viewpoint of improving vibration resistance, it is preferable to stably hold the electrode body 140 within the housing 120. By stably holding the electrode body 140, movement of the electrode body 140 within the housing 120 is suppressed, thereby suppressing malfunctions caused by damage to the connection between the electrode body 140 and the current collector (not shown).

[0061] On the other hand, the square housing 120 has the characteristic of high rigidity at its ends (the outer periphery of the first side 123 and the second side 124).

[0062] exist Figure 6 In the example shown (comparative example), since the diaphragm 200 has the same thickness throughout the entire area of ​​the housing 120, there is a tendency for the constraint force to be large at the ends of the rigid housing 120 and small at the center of the electrode body 140.

[0063] In contrast, Figure 5 In the example shown (an embodiment of the present technology), since the area where the elastomer 220 is provided (the abutting area of ​​the diaphragm 200) is defined, the thickness of the diaphragm 200 is reduced at the end of the housing 120, so that the restraining force can be concentrated in the central part of the electrode body 140, thereby stably holding the electrode body 140 within the housing 120.

[0064] Here, the area of ​​the long side surface (first side surface 123 and second side surface 124) of the battery 100 is set as S1, and the area of ​​the thick-walled portion of the separator 200 (in the form of...) is... Figure 7 In the case of a component with multiple protrusions, the area of ​​the region formed by connecting the multiple protrusions located on the outermost periphery) or the contact portion ( Figure 5When the area of the elastic body 220 in the example (the area of the elastic body 220 in the example) is set to S2, the ratio of S1 to S2 (S1 / S2) is preferably 1.05 or more and 1.67 or less. In addition, S2 is preferably 85% or less of S1 (1.18 or less of S1 / S2).

[0065] However, the ratio of S1 to S2 is not limited to the above range. In general, the smaller the battery 100, the more the value of S1 / S2 preferably tends to be large.

[0066] In addition, the thick wall portion or the abutting portion (S2) of the separator 200 is preferably 80% or more, and more preferably 90% or more, of the area of the contact portion where the electrode body 140 contacts the inner surface of the case 120 (the area excluding the R portion in the case of the electrode body 140 being a jelly-roll type).

[0067] Figure 7 is a graph schematically showing a device for finding the relationship between the compression rate and the load of the separator 200. Figure 8 is a graph showing the relationship between the compression rate and the load of the separator 200.

[0068] As shown in Figure 7 , 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 found. The compression rate is found by the following equation.

[0069] Compression rate = (L0 - L) / L0

[0070] As shown in Figure 8 , the slope of the compression rate-load curve until the compression rate becomes 0.2 (20%) is determined as the "elastic coefficient" of the separator 200. The "elastic coefficient" of the separator 200 according to the present embodiment is preferably 1 MPa or more and 10 MPa or less.

[0071] The embodiments of the present application have been described, but it should be considered that the embodiments disclosed this time are illustrative in all respects and are not restrictive. The scope of the present application is shown by the claims, and is intended to include all modifications equivalent in meaning and scope to the claims.

Claims

1. A battery pack characterized by comprising: Possessing: a plurality of batteries arranged in a first direction, each including a case that houses an electrode body; and an insulating member provided between the plurality of batteries, the insulating member includes a first portion and a second portion arranged in the first direction, the first portion is provided in a first region including a region of the case of the plurality of batteries when viewed in the first direction, the second portion is provided in a second region formed inward of the region of the case of the plurality of batteries when viewed in the first direction, the second portion abuts against at least one of the batteries on a side of the insulating member, the thermal insulation property of the first portion is equal to or higher than that of the second portion.

2. The battery pack according to claim 1, wherein the first portion and the second portion are composed of the same raw material.

3. The battery pack according to claim 1, wherein the thermal insulation property of the first portion is higher than that of the second portion.

4. The battery pack according to claim 1, wherein the elastic coefficient of the second portion is lower than that of the first portion.

5. The battery pack according to any one of claims 1 to 4, wherein in a case where a slope of a compression rate-load curve until a compression rate of the insulating member becomes 20% is determined as the elastic coefficient of the insulating member, the elastic coefficient of the insulating member is 1 MPa or higher and 10 MPa or lower.

6. The battery pack according to any one of claims 1 to 4, wherein the thermal conductivity of the first portion is 0.15 W / mK or lower.

7. The battery pack according to any one of claims 1 to 4, wherein a thickness of the insulating member in the first direction is 20 mm or lower.

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