Secondary battery

Abstract

To provide a secondary battery that can reduce temperature rises due to heat generation from an electrode body group including a plurality of electrode bodies, even when the electrode body group is housed in a case.SOLUTION: A secondary battery includes an electrode body group including a first electrode body and a second electrode body, a first heat sink disposed between the first and second electrode bodies, a case housing the electrode body group and the first heat sink, and a second heat sink housed in the case and disposed between an outer circumferential surface of the electrode body group and the case. The first and second heat sinks each have a thermal conductivity of 25 W / m K or more and a volume resistivity of 1×1013 Ω cm or more.SELECTED DRAWING: Figure 5

Description

[Technical Field]

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

[0002] In order to reduce the weight of a secondary battery, it is known to house a plurality of electrode bodies in a case (for example, Patent Document 1, etc.). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-45560 Summary of the Invention [Problem to be solved by the invention]

[0004] Secondary batteries generate heat as the electrode assembly is charged and discharged, causing the temperature to rise and resulting in a decrease in battery performance. Secondary batteries that house multiple electrode assemblies in a case tend to generate a large amount of heat, so it is necessary to suppress the temperature rise that occurs when the secondary battery is charged and discharged.

[0005] An object of the present invention is to provide a secondary battery that can reduce the temperature rise caused by heat generation of an electrode assembly even when the electrode assembly assembly including a plurality of electrode assemblies is housed in a case. [Means for solving the problem]

[0006] [1] An electrode body group including a first electrode body and a second electrode body; a first heat sink disposed between the first electrode body and the second electrode body; a case that accommodates the electrode group and the first heat sink; a second heat sink housed in the case and disposed between the outer circumferential surface of the electrode assembly and the case, The first heat sink and the second heat sink each have a thermal conductivity of 25 W / m·K or more and a thermal conductivity of 1×10 13A secondary battery with a volume resistivity of Ω·cm or higher. [2] The secondary battery according to [1], wherein the first heat sink and the second heat sink are formed to be heat-transferable. [3] The secondary battery according to [1] or [2], wherein the first heat sink and the second heat sink each have a thermal conductivity of 130 W / m·K or more. [4] The secondary battery according to any one of [1] to [3], wherein the first heat sink and the second heat sink each contain aluminum nitride. [5] The secondary battery according to any one of [1] to [4], wherein the second heat sink is an electrode assembly holder that houses the electrode assembly group in its internal space. [6] The first electrode body and the second electrode body each have a structure in which a negative electrode, a positive electrode, and a separator interposed between the negative electrode and the positive electrode are stacked, the first electrode body and the second electrode body in the electrode body group are arranged so that the stacking directions of the negative electrode, the positive electrode, and the separator are the same; the electrode body group has a first electrode tab group arranged at a first end and a second electrode tab group arranged at a second end opposite the first end, an outer peripheral surface of the electrode body group has a first end surface on which the first electrode tab group is provided and a second end surface on which the second electrode tab group is provided; The secondary battery according to any one of [1] to [5], wherein in the electrode body group, the length in a first direction in which the first end surface and the second end surface are aligned is greater than the length in the stacking direction and is greater than the length in a second direction perpendicular to the first direction and the stacking direction. [7] The secondary battery according to [6], wherein the second heat sink is disposed between the case and all surfaces of the outer peripheral surface of the electrode assembly except for the first end surface and the second end surface. [8] In the first direction, when the length of the first heat sink is Lhx and the length of the separator in the first electrode body or the second electrode body is Lsx, the following formula (I) is satisfied: 0.97≦Lhx / Lsx<1 (I) The secondary battery according to [6] or [7], which satisfies the relationship: [Effects of the Invention]

[0007] According to the secondary battery of the present disclosure, even if an electrode assembly including a plurality of electrode assemblies is housed in a case, the temperature rise due to heat generation of the electrode assembly can be reduced. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view showing a configuration of a secondary battery according to an embodiment. [Figure 2] 2 is a front view showing the configuration of the secondary battery shown in FIG. [Figure 3] FIG. 3 is a front cross-sectional view of the secondary battery shown in FIG. [Figure 4] FIG. 10 is a perspective view showing a state in which a second heat dissipation plate is attached to the electrode assembly. [Figure 5] FIG. 2 is a VV cross-sectional view of the secondary battery shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] 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.

[0010] In the embodiments described below, when numbers, amounts, etc. are mentioned, unless otherwise specified, the scope of the present technology is not necessarily limited to those numbers, amounts, etc. Furthermore, in the embodiments described below, 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 mentioned in the present embodiments.

[0011] In this specification, the words "comprise," "include," and "have" are open-ended, meaning that when a certain feature is included, other features may or may not be included.

[0012] When geometric terms and terms expressing positional or directional relationships, such as "parallel," "orthogonal," and "along," are used in this specification, these terms allow for manufacturing errors and slight variations. When terms expressing relative positional relationships, such as "top," "bottom," and "side," are used in this specification, these terms are used to indicate relative positional relationships in one 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).

[0013] In this specification, unless otherwise specified, a numerical range such as "m to n" includes both the upper and lower limits. That is, "m to n" represents a numerical range of "m or more and n or less." Any numerical value selected from within the numerical range may be used as a new upper or lower limit. For example, a new numerical range may be set by arbitrarily combining a numerical value within the numerical range with a numerical value described elsewhere in this specification.

[0014] In this specification, the term "secondary battery" is not limited to lithium ion batteries, but may include other secondary batteries such as nickel-metal hydride batteries and sodium ion batteries.

[0015] In the drawings, if the electrode body of the secondary battery is a laminated electrode body, the longitudinal direction of the laminated surface is the X direction (first direction), and if the electrode body is a wound electrode body, the direction along the winding axis is the X direction (first direction). The shorter side direction of the electrode body as viewed from the X direction is the Y direction (lamination direction), and the direction perpendicular to the X and Y directions, i.e., the longitudinal direction of the electrode body as viewed from the X direction and perpendicular to the X direction, is the Z direction (second direction). To facilitate understanding of the invention, the dimensions of each component in the drawings may be altered from their actual dimensions.

[0016] In this specification, the "X direction," "Z direction," and "Y direction" used to describe a secondary battery, an electrode body, an electrode body group, a case body, etc. may be referred to as the "width direction," "height direction," and "thickness direction," respectively.

[0017] (Overall configuration of secondary battery) Fig. 1 is a perspective view showing the configuration of a secondary battery according to an embodiment. Fig. 2 is a front view showing the configuration of the secondary battery shown in Fig. 1. Fig. 3 is a front cross-sectional view of the secondary battery shown in Fig. 2. Fig. 4 is a perspective view showing a state in which a second heat sink is attached to an electrode body group. Fig. 5 is a VV cross-sectional view of the secondary battery shown in Fig. 1.

[0018] As shown in FIGS. 1 to 5, the secondary battery 1 includes a case 100, an electrode assembly 200, an electrode terminal 300, a current collector 400, and a heat sink 700.

[0019] The case 100 houses the electrode assembly 200 and a heat sink 700. As shown in FIGS. 4 and 5, the heat sink 700 includes a first heat sink 701 and a second heat sink 702, which will be described later. The first heat sink 701 and the second heat sink 702 are housed in the case 100 together with the electrode assembly 200. The electrode assembly 200 is housed in the case 100 together with an electrolyte, in a state where it is disposed in an internal space formed by the second heat sink 702 (FIG. 4). The electrolyte is a non-aqueous solvent such as an organic solvent containing an electrolyte. The second heat sink 702 is disposed between the electrode assembly 200 and the case 100, and may be an electrode holder that houses the electrode assembly 200 in the internal space.

[0020] The case 100 can include a case body 110, a first sealing plate 120, and a second sealing plate 130. The case body 110 is cylindrical, preferably rectangular. The corners of the rectangular cylinder may be rounded. The case body 110, the first sealing plate 120, and the second sealing plate 130 are each made of metal, such as aluminum, an aluminum alloy, iron, or an iron alloy.

[0021] In this embodiment, the length of the case body 110 in the width direction (X direction) of the secondary battery 1 is greater than the lengths of the secondary battery 1 in the thickness direction (Y direction) and height direction (Z direction). The dimension (width) of the case body 110 in the X direction is preferably 30 cm or more. This allows for the construction of a relatively large (high-capacity) secondary battery 1. The dimension (height) of the case body 110 in the Z direction is preferably 20 cm or less, more preferably 15 cm or less, and even more preferably 10 cm or less. This allows for the construction of a relatively low-height secondary battery 1, which improves the mountability in, for example, a vehicle.

[0022] The case main body 110 includes a pair of first side surface portions 111 and a pair of second side surface portions 112. The pair of first side surface portions 111 constitute part of the side surfaces of the case 100. The pair of second side surface portions 112 constitute the bottom surface portion and the top surface portion of the case 100. The pair of first side surface portions 111 and the pair of second side surface portions 112 are arranged to intersect with each other. The pair of first side surface portions 111 and the pair of second side surface portions 112 are connected at their respective ends. The area of ​​each of the pair of first side surface portions 111 is preferably larger than the area of ​​each of the pair of second side surface portions 112.

[0023] A first opening is provided at an end of case body 110 on a first side in the X direction. As shown in FIGS. 1 to 3, the first opening is sealed by a first sealing plate 120, and case body 110 and first sealing plate 120 are joined by a joint. The first opening and first sealing plate 120 have a roughly rectangular shape with the Y direction as the short side direction and the Z direction as the long side direction. The roughly rectangular shape includes a rectangular shape or a substantially rectangular shape such as a rectangular shape with rounded corners.

[0024] A negative electrode terminal 301 (electrode terminal 300) is provided on the first sealing plate 120. The position of the negative electrode terminal 301 can be changed as appropriate. The negative electrode terminal 301 is electrically connected to the negative electrode of the electrode assembly 200. The negative electrode terminal 301 is attached to the first sealing plate 120, i.e., the case 100. The negative electrode terminal 301 can be made of a conductive material, and can be made of a metal such as copper or a copper alloy, for example.

[0025] A second opening is provided at the end of a second side of case body 110 opposite the end of the first side in the X direction. The second opening is located at the end opposite the first opening, and the first and second openings face each other. As shown in FIGS. 1 to 3, the second opening is sealed with a second sealing plate 130, and case body 110 and second sealing plate 130 are joined by a joint. The second opening and second sealing plate 130 have a substantially rectangular shape with the Y direction as the short side and the Z direction as the long side.

[0026] A positive electrode terminal 302 (electrode terminal 300) and a liquid inlet 134 are provided on the second sealing plate 130. The positions of the positive electrode terminal 302 and the liquid inlet 134 can be changed as appropriate. The positive electrode terminal 302 is electrically connected to the positive electrode of the electrode assembly 200. The positive electrode terminal 302 is attached to the second sealing plate 130, i.e., the case 100. The positive electrode terminal 302 can be made of a conductive material, and can be made of a metal such as aluminum or an aluminum alloy. The liquid inlet 134 is sealed with a sealing member (not shown). For example, a blind rivet or other metal member can be used as the sealing member.

[0027] The electrode assembly 200 includes a first electrode assembly 201 and a second electrode assembly 202 (hereinafter simply referred to as "electrode assembly 201, 202"). The electrode assembly 200 is sufficient as long as it includes at least the electrode assembly 201, 202, and may include electrode assembly other than the electrode assembly 201, 202. The number of electrode assembly included in the electrode assembly 200 is not particularly limited, but is preferably 2 to 4, more preferably 2 or 4, and even more preferably 2.

[0028] Each of the electrode bodies 201 and 202 has a structure in which a negative electrode, a positive electrode, and a separator interposed between the negative and positive electrodes are stacked. Each of the electrode bodies 201 and 202 may be a stacked electrode body in which a plurality of negative electrodes and a plurality of positive electrodes are alternately stacked with separators interposed therebetween, or may be a wound electrode body in which a strip-shaped laminate in which a strip-shaped negative electrode and a strip-shaped positive electrode are stacked with a strip-shaped separator interposed therebetween is wound. When the electrode bodies 201 and 202 are wound electrode bodies, they preferably have a flat shape that is pressed after being wound.

[0029] The electrode bodies 201, 202 in the electrode body group 200 are arranged so that the stacking directions of the respective negative electrodes, positive electrodes, and separators are the same. For example, in the secondary battery 1 shown in FIGS. 1 to 5, the stacking direction of the negative electrodes, positive electrodes, and separators is the Y direction, and the first electrode body 201 and the second electrode body 202 are arranged in this Y direction. When the electrode bodies 201, 202 are stacked electrode bodies, the electrode body group 200 is formed so that the electrode bodies 201, 202 are arranged so that the respective negative electrodes, positive electrodes, and separators are stacked in the Y direction. When the electrode bodies 201, 202 are wound electrode bodies, the electrode body group 200 is formed so that the electrode bodies 201, 202 are arranged in the Y direction so that the winding axes of each are parallel to each other. As a result, the electrode bodies 201, 202, which are wound electrode bodies, are also arranged so that the stacking directions of the negative electrodes, positive electrodes, and separators are the same. The first electrode body 201 and the second electrode body 202 in the electrode body group 200 are preferably arranged so that the faces with the largest areas among the faces constituting the outer surfaces (in this embodiment, the faces of the electrode bodies 201, 202 facing the pair of first side surface portions 111 of the case body 110) face each other (FIG. 4).

[0030] As shown in FIGS. 3 and 4 , the electrode assembly 200 includes a main body portion, a negative electrode tab group 220 (first electrode tab group), and a positive electrode tab group 250 (second electrode tab group). The main body portion is a portion where the negative electrodes, positive electrodes, and separators of the electrode assemblies 201, 202 are stacked, and corresponds to the rectangular portion excluding the negative electrode tab group 220 and the positive electrode tab group 250. The negative electrode tab group 220 is a portion where the negative electrode tabs of the electrode assemblies 201, 202 are stacked. The positive electrode tab group 250 is a portion where the positive electrode tabs of the electrode assemblies 201, 202 are stacked. The negative electrode tab group 220 and the positive electrode tab group 250 are formed to protrude from the main body portion toward the first sealing plate 120 and the second sealing plate 130, respectively. The negative electrode tab group 220 is arranged at a first end, that is, in this embodiment, at one end of the electrode body group 200 in the X direction relative to the main body. The first end side in this embodiment is the first sealing plate 120 side. The positive electrode tab group 250 is arranged at a second end opposite the first end, that is, the end opposite the first end side of the electrode body group 200 in the X direction relative to the main body. The second end side in this embodiment is the second sealing plate 130 side.

[0031] The outer peripheral surface of the electrode assembly 200 has a first end face on which the negative electrode tab group 220 is provided at a first end, and a second end face on which the positive electrode tab group 250 is provided at a second end opposite the first end. In this embodiment, the second end face is located opposite the first end face in the X direction, which is the first direction in which the first end face and the second end face are aligned. In the electrode assembly 200, the length in the X direction (first direction) is longer than the length in the stacking direction (Y direction) of the negative electrodes, positive electrodes, and separators, and is also longer than the length in the Z direction (second direction) perpendicular to the X direction and the stacking direction. Similarly, the length in the X direction (width direction, first direction) of the electrode assemblies 201 and 202 is longer than the lengths in the Y direction (thickness direction, stacking direction) and the Z direction (height direction, second direction). The electrode assembly 200 is housed in the case 100 so that its longitudinal direction is parallel to the X direction.

[0032] The negative electrode includes a negative electrode current collector foil and a negative electrode active material layer formed on the negative electrode current collector foil. The negative electrode current collector foil is copper foil or copper alloy foil. The negative electrode active material layer can be formed on one or both sides of the negative electrode current collector foil. The negative electrode active material layer includes a negative electrode active material such as graphite, and may further include a binder such as carboxymethyl cellulose and styrene butadiene rubber, and a conductive additive such as carbon black and fibrous carbon. One end of the negative electrode is provided with a negative electrode tab formed from a negative electrode current collector foil on which no negative electrode active material layer is formed. When the electrode bodies 201 and 202 are laminated electrode bodies, the negative electrode tabs provided on each negative electrode are stacked to form the negative electrode tab group 220. When the electrode bodies 201 and 202 are wound electrode bodies, the negative electrode tab group 220 is formed by stacking multiple negative electrode tabs formed on strip-shaped negative electrodes. The length and shape of each of the multiple negative electrode tabs in the protruding direction are adjusted appropriately taking into consideration the state in which negative electrode tab group 220 is connected to negative electrode current collector 401.

[0033] The positive electrode includes a positive electrode current collector foil and a positive electrode active material layer formed on the positive electrode current collector foil. The positive electrode current collector foil is an aluminum foil or an aluminum alloy foil. The positive electrode active material layer can be formed on one or both sides of the positive electrode current collector foil. The positive electrode active material layer includes a positive electrode active material such as a lithium transition metal composite oxide, and may further include a binder such as polyvinylidene fluoride and a conductive additive such as carbon black and fibrous carbon. A positive electrode tab formed from a positive electrode current collector foil on which no positive electrode active material layer is formed is provided at one end of the positive electrode. When the electrode bodies 201 and 202 are laminated electrode bodies, the positive electrode tabs provided on each positive electrode are stacked to form a positive electrode tab group 250. When the electrode bodies 201 and 202 are wound electrode bodies, the positive electrode tab group 250 is formed by stacking multiple positive electrode tabs formed on strip-shaped positive electrodes. The length and shape of each of the multiple positive electrode tabs in the protruding direction are adjusted appropriately taking into consideration the state in which the positive electrode tab group 250 is connected to the positive electrode current collector 402.

[0034] 3, the current collector 400 includes a negative electrode current collector 401 and a positive electrode current collector 402. The negative electrode current collector 401 and the positive electrode current collector 402 are each formed of a plate-like member. The electrode assembly 200 is electrically connected to the negative electrode terminal 301 via the negative electrode tab group 220 and the negative electrode current collector 401, and is electrically connected to the positive electrode terminal 302 via the positive electrode tab group 250 and the positive electrode current collector 402.

[0035] The negative electrode current collector 401 is disposed on the first sealing plate 120 via a resin insulating member. The negative electrode current collector 401 is electrically connected to the negative electrode tab group 220 and the negative electrode terminal 301. The negative electrode current collector 401 can be formed from a conductive material, for example, a metal such as aluminum or an aluminum alloy. The negative electrode current collector 401 has a first conductive member 410 (FIG. 4) joined to the negative electrode tab group 220, and a second conductive member joined to the negative electrode terminal 301. The first conductive member 410 and the second conductive member are electrically connected to form the negative electrode current collector 401 (FIG. 3).

[0036] The positive electrode current collector 402 is disposed on the second sealing plate 130 via a resin insulating member. The positive electrode current collector 402 is electrically connected to the positive electrode tab group 250 and the positive electrode terminal 302. The positive electrode current collector 402 can be formed from a conductive material, for example, a metal such as aluminum or an aluminum alloy. The positive electrode current collector 402 has a third conductive member 420 (FIG. 4) joined to the positive electrode tab group 250, and a fourth conductive member joined to the positive electrode terminal 302. The third conductive member 420 and the fourth conductive member are electrically connected to form the positive electrode current collector 402 (FIG. 3).

[0037] A first spacer 601 is disposed between the first sealing plate 120 and the main body of the electrode assembly 200 (FIG. 4). A second spacer 602 is disposed between the second sealing plate 130 and the main body of the electrode assembly 200 (FIG. 4). The first spacer 601 and the second spacer 602 (hereinafter also referred to as "spacers 601, 602") are formed of an insulating material. The negative electrode tab group 220 passes through the inside of the first spacer 601 and is thereby protected by the first spacer 601. The positive electrode tab group 250 passes through the inside of the second spacer 602 and is thereby protected by the second spacer 602. This prevents electrical contact between the negative electrode tab group 220 and the positive electrode tab group 250 and the first sealing plate 120 and the second sealing plate 130. It is also possible to prevent electrical contact between the negative electrode tab group 220 and the positive electrode tab group 250 and the first side surface portion 111 and the second side surface portion 112 of the case body 110. The secondary battery 1 may be configured without the spacers 601, 602.

[0038] A part of the spacers 601, 602 can have a plate portion facing a part of the first end face (described above) and a part of the second end face (described above) of the electrode assembly 200. The plate portion may abut against the main body portion of the electrode assembly 200, and even if it does not abut against the main body portion, the shortest distance to the electrode assembly 200 is preferably within 2 mm, more preferably within 1 mm.

[0039] Examples of insulating materials for forming the spacers 601, 602 include resin materials such as polypropylene (PP), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyimide (PI), and polyolefin (PO); and materials for forming the heat sink 700 described below. When the spacers 601, 602 are formed from a material for forming the heat sink 700, the spacers 601, 602 can also function as the heat sink 700 described below.

[0040] (Structure and characteristics of heat sink) 4 and 5, heat dissipation plate 700 includes a first heat dissipation plate 701 and a second heat dissipation plate 702, which will be described later. First heat dissipation plate 701 and second heat dissipation plate 702 may be separate members, or may be formed integrally.

[0041] As shown in FIG. 5 , the first heat sink 701 is housed in the case 100 together with the electrode assembly 200. The first heat sink 701 is disposed between the first electrode assembly 201 and the second electrode assembly 202 housed in the case 100. There may be a gap between the first electrode assembly 201 and the first heat sink 701, so that they do not come into contact with each other. From the viewpoint of improving the heat dissipation efficiency of the first heat sink 701, the first electrode assembly 201 and the first heat sink 701 may come into contact with each other. There may be a gap between the second electrode assembly 202 and the first heat sink 701, so that they do not come into contact with each other. From the viewpoint of improving the heat dissipation efficiency of the first heat sink 701, the first heat sink 701 and the electrode assembly 200 may come into contact with each other.

[0042] The first heat sink 701 is preferably disposed in a range facing the main body portion (the portion where the negative electrodes and positive electrodes are stacked with the separator interposed therebetween) of the electrode body group 200. The first heat sink 701 is preferably not disposed in a position facing the negative electrode tab group 220 and the positive electrode tab group 250.

[0043] As shown in FIG. 3, when the length of the first heat sink 701 in the X direction (first direction) is Lhx and the length of the separator in the first electrode body 201 or the second electrode body 202 is Lsx, it is preferable that the secondary battery 1 satisfies the relationship of formula (I). 0.97≦Lhx / Lsx<1 (I)

[0044] Lsx is the length in the X direction of the separator on the surface of the electrode assemblies 201, 202 facing the first heat sink 701. Lsx may be the length of the separator of the first electrode assembly 201, or may be the length of the separator of the second electrode assembly 202. Lhx / Lsx may be 0.98 to 0.99. When Lhx / Lsx is within the above range, in the secondary battery 1, the heat sink area of ​​the first heat sink 701 can be increased while reducing contact between the negative electrode tab group 220 and the positive electrode tab group 250 and the first heat sink 701.

[0045] As shown in FIG. 5, when the length of the first heat sink 701 in the Z direction (height direction) is Lhz and the length of the electrode body group 200 in the Z direction is Lez, it is preferable that the secondary battery 1 satisfies the relationship of formula (II). Lhz / Lez≧1 (II)

[0046] Lez is the length in the Z direction of the surface of the electrode assemblies 201, 202 facing the first heat sink 701. In this embodiment, the Z direction is the direction perpendicular to the X direction of the surface of the electrode assemblies 201, 202 facing the first heat sink 701. Lhz / Lez may be greater than 1, may be 1 to 1.2, may be greater than 1 but not greater than 1.1, or may be 1.01 to 1.07. When Lhz / Lez is within the above range, the heat dissipation area of ​​the heat sink 702 can be increased. When the secondary battery 1 satisfies the relationship of formulas (I) and (II), the heat dissipation area of ​​the second heat sink 702 can be increased, thereby improving heat dissipation efficiency.

[0047] The second heat sink 702 is housed in the case 100 and is disposed between the outer peripheral surface of the electrode assembly 200 and the case 100. As shown in FIGS. 4 and 5, the second heat sink 702 is disposed so as to face at least a portion of the outer peripheral surface of the electrode assembly 200. The second heat sink 702 faces 50% or more, and more preferably 70% or more, of the area of ​​the outer peripheral surface of the electrode assembly 200. A gap may exist between the second heat sink 702 and the electrode assembly 200, and the second heat sink 702 and the electrode assembly 200 may not be in contact with each other. From the viewpoint of improving the heat dissipation efficiency of the second heat sink 702, it is preferable that the second heat sink 702 and the electrode assembly 200 be in contact with each other.

[0048] When secondary battery 1 has spacers 601, 602 between first sealing plate 120 and second sealing plate 130 and the main body of electrode assembly 200 (FIG. 4), second heat dissipation plate 702 may also be disposed between the outer peripheral surfaces of spacers 601, 602 and case 100. In this case, second heat dissipation plate 702 may be fixed to the outer peripheral surfaces of spacers 601, 602. Methods for fixing second heat dissipation plate 702 to spacers 601, 602 include thermal welding, taping, adhesive bonding, fitting, hooking, etc.

[0049] When the secondary battery 1 has spacers 601, 602, the second heat sink 702 may include the spacers 601, 602, i.e., a portion of the second heat sink 702 may function as the entire spacers 601, 602 or as part of the spacers 601, 602. For example, the second heat sink 702 may constitute the plate portions (described above) of the spacers 601, 602 that face the first end surface and the second end surface of the electrode assembly 200, i.e., the second heat sink 702 may include the plate portions. Alternatively, the second heat sink 702 may constitute the spacers 601, 602. The second heat sink 702 may include only one of the spacers 601, 602, or may include only one of the plate portions of the first spacer 601 and the second spacer 602.

[0050] The second heat sink 702 is preferably not disposed between the first end face (the face on which the negative electrode tab group 220 is provided) of the electrode assembly 200 and the case 100, and between the second end face (the face on which the positive electrode tab group 250 is provided) and the case 100. The second heat sink 702 is preferably disposed between all faces of the outer circumferential surface of the electrode assembly 200 except for the first and second end faces (hereinafter also referred to as "the remaining faces") and the case 100. The second heat sink 702 that faces all the remaining faces may face only a portion of each of the remaining faces, may face only the entirety of each of the remaining faces, or may be a mixture of these.

[0051] The second heat sink 702 is preferably arranged to face the entire outer peripheral surface of the main body portion of the electrode assembly 200, and more preferably, to face at least the base sides (portions on the main body portion side) of the negative electrode tab group 220 and the positive electrode tab group 250. The second heat sink 702 may be arranged to face the main body portion, the entire surface of the negative electrode tab group 220, and the entire positive electrode tab group 250. By arranging the second heat sink 702 to face the negative electrode tab group 220 and the positive electrode tab group 250, electrical contact between the negative electrode tab group 220 and the positive electrode tab group 250 and the case 100 is reduced, thereby maintaining insulation between the electrode assembly 200 and the case 100. As described above, the second heat sink 702 arranged between the negative electrode tab group 220 and the positive electrode tab group 250 and the case 100 may be the spacers 601, 602.

[0052] 4 and 5, the second heat sink 702 is preferably formed in a cylindrical shape so as to face all of the remaining surfaces of the electrode assembly 200. This increases the heat dissipation area of ​​the second heat sink 702, improving heat dissipation efficiency and making it easier to maintain insulation between the electrode assembly 200 and the case 100. The cylindrical second heat sink 702 may be formed by bending a plate-shaped or sheet-shaped member. The bent plate-shaped or sheet-shaped member may be formed into a cylindrical shape by abutting the edges together, or by overlapping the edges together.

[0053] It is preferable that first heat sink 701 and second heat sink 702 are formed to be heat conductive. Methods for forming them to be heat conductive include a method of connecting first heat sink 701 and second heat sink 702 by bringing them into contact with each other, a method of integrally forming first heat sink 701 and second heat sink 702 by bending a single plate-like member or a single sheet-like member to form first heat sink 701 and second heat sink 702, or a combination of these. This allows heat from first heat sink 701 to be transferred to second heat sink 702, so that the heat from first heat sink 701 can be efficiently dissipated from second heat sink 702.

[0054] The first heat sink 701 and the second heat sink 702 (hereinafter simply referred to as "heat sinks 701, 702") each have a thermal conductivity of 25 W / m·K or more and a thermal conductivity of 1×10 13 It has a volume resistivity of Ω·cm or more. In this specification, thermal conductivity and volume resistivity are each values ​​at a temperature of 25°C.

[0055] The thermal conductivity of each of the heat sinks 701 and 702 may be 100 W / m·K or more, preferably 130 W / m·K or more, 150 W / m·K or more, or even 200 W / m·K or more. The thermal conductivity of the heat sinks 701 and 702 is typically 250 W / m·K or less. The thermal conductivities of the heat sinks 701 and 702 may be the same or different from each other. When the second heat sink 702 includes spacers 601 and 602, the portions of the second heat sink 702 that are surrounded by the spacers 601 and 602 and the remaining portions of the second heat sink 702 may have the same or different thermal conductivities. The thermal conductivity of the heat sinks 701 and 702 is determined by a method in accordance with ASTM D5470.

[0056] The volume resistivity of the heat sinks 701 and 702 is 5×10 13 It may be 1×10 Ω·cm or more. 14 It may be 5×10 Ω·cm or more. 14 The volume resistivity of the heat sinks 701 and 702 may be 1×10 16 The volume resistivity of the heat sinks 701, 702 may be the same as or different from each other. When the second heat sink 702 includes the spacers 601, 602, the spacer 601, 602 portions of the second heat sink 702 and the remaining portions may have the same or different volume resistivities. The volume resistivity of the heat sinks 701, 702 is determined by a method conforming to JIS C2141.

[0057] The thermal conductivity and volume resistivity of the heat sinks 701 and 702 can be arbitrarily combined within the respective ranges described above. The thermal conductivity and volume resistivity of the heat sinks 701 and 702 may be the same or different, or the thermal conductivity may be the same but the volume resistivity is different, or the volume resistivity may be the same but the thermal conductivity is different.

[0058] The heat sinks 701 and 702 can be formed using a material having the above-described thermal conductivity and volume resistivity. Such materials include one or more selected from the group consisting of aluminum nitride, silicon nitride, aluminum oxide, and diamond-like carbon. The materials forming the heat sinks 701 and 702 may be the same or different. From the viewpoint of achieving excellent thermal conductivity and volume resistivity, it is preferable that the heat sinks 701 and 702 each contain aluminum nitride.

[0059] The secondary battery 1 generates heat as the electrode assembly 200 housed in the case 100 is charged and discharged. The amount of heat generated increases when the secondary battery 1 is rapidly charged. The secondary battery 1 includes a first heat sink 701 disposed between the two electrode assemblies 201 and 202 included in the electrode assembly 200, and a second heat sink 702 disposed between the outer circumferential surface of the electrode assembly 200 and the case 100. Therefore, heat generated in the electrode assembly 200 can be dissipated from the heat sinks 701 and 702. The secondary battery 1 includes the first heat sink 701, which increases the heat dissipation area compared to a battery having only the second heat sink 702, thereby improving heat dissipation efficiency. Furthermore, heat generated in the electrode assembly 200 can be efficiently dissipated even when the secondary battery 1 is rapidly charged. This shortens the charging time of the secondary battery 1 and increases the number of times it can be charged per day, thereby providing a secondary battery 1 with excellent rapid charging performance.

[0060] Because the heat sinks 701 and 702 have the above-described volume resistivity, they can maintain insulation between the first electrode body 201 and the second electrode body 202 and between the electrode body group 200 and the case 100. Therefore, the second heat sink 702 can be used not only as a heat sink member, but also as an electrode body holder that is disposed between the electrode body group 200 and the case 100 and that insulates the electrode body group 200 from the case 100. When the second heat sink 702 is an electrode body holder, the first heat sink 701 can be used as a partition wall that divides the inside of the electrode body holder and forms internal spaces that accommodate the first electrode body 201 and the second electrode body 202, respectively.

[0061] In this embodiment, the case where the electrode body group 200 has the electrode bodies 201 and 202 has been described, but the electrode body group 200 may include three or more electrode bodies. When the electrode body group 200 includes three or more electrode bodies, it is sufficient that the first heat dissipation plate 701 is disposed somewhere between adjacent electrode bodies, but it is preferable to dispose the first heat dissipation plate 701 between all adjacent electrode bodies.

[0062] In this embodiment, the case where the negative electrode tab group 220 and the positive electrode tab group 250 are respectively arranged at each end of the electrode body group 200 in the X direction (first direction) has been described, but this is not limiting. For example, in the electrode body group 200, the negative electrode tab group 220 and the positive electrode tab group 250 may be arranged at the same end.

[0063] In this embodiment, a case has been described in which the length of the electrode group 200 in the X direction (first direction) is greater than the lengths in the Y direction (stacking direction) and the Z direction (second direction), but this is not limited to this, and the length in each direction can be set appropriately.

[0064] 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]

[0065] 1 secondary battery, 100 case, 110 case body, 111 first side surface portion, 112 second side surface portion, 120 first sealing plate, 130 second sealing plate, 134 liquid inlet, 200 electrode assembly group, 201 first electrode assembly, 202 second electrode assembly, 220 negative electrode tab assembly (first electrode tab assembly), 250 positive electrode tab assembly (second electrode tab assembly), 300 electrode terminal, 301 negative electrode terminal (electrode terminal), 302 positive electrode terminal (electrode terminal), 400 current collector, 401 negative electrode current collector (current collector), 402 positive electrode current collector (current collector), 410 first conductive member (negative electrode current collector), 420 third conductive member (positive electrode current collector), 601 first spacer, 602 second spacer, 700 heat sink, 701 1st heat sink (heat sink), 702 2nd heat sink (heat sink).

Claims

1. an electrode body group including a first electrode body and a second electrode body; a first heat sink disposed between the first electrode body and the second electrode body; a case that accommodates the electrode group and the first heat sink; a second heat sink housed in the case and disposed between the outer circumferential surface of the electrode assembly and the case, The first heat sink and the second heat sink each have a thermal conductivity of 25 W / m·K or more, and １３ A secondary battery having a volume resistivity of Ω·cm or more.

2. The secondary battery according to claim 1 , wherein the first heat dissipation plate and the second heat dissipation plate are formed to be heat transferable.

3. The secondary battery according to claim 1 , wherein the first heat sink and the second heat sink each have a thermal conductivity of 130 W / m·K or more.

4. The secondary battery according to claim 1 , wherein the first heat sink and the second heat sink each contain aluminum nitride.

5. The secondary battery according to claim 1 , wherein the second heat sink is an electrode assembly holder that accommodates the electrode assembly in an internal space thereof.

6. the first electrode body and the second electrode body each have a structure in which a negative electrode, a positive electrode, and a separator interposed between the negative electrode and the positive electrode are stacked; the first electrode body and the second electrode body in the electrode body group are arranged so that the stacking directions of the negative electrode, the positive electrode, and the separator are the same; the electrode body group has a first electrode tab group arranged at a first end and a second electrode tab group arranged at a second end opposite the first end, an outer peripheral surface of the electrode body group has a first end surface on which the first electrode tab group is provided and a second end surface on which the second electrode tab group is provided; 2. The secondary battery of claim 1, wherein the length of the electrode assembly in a first direction in which the first end surface and the second end surface are aligned is greater than the length in the stacking direction and greater than the length in a second direction perpendicular to the first direction and the stacking direction.

7. The secondary battery according to claim 6 , wherein the second heat sink is disposed between the case and all surfaces of the outer circumferential surface of the electrode assembly except for the first end surface and the second end surface.

8. In the first direction, when the length of the first heat dissipation plate is Lhx and the length of the separator in the first electrode body or the second electrode body is Lsx, the following formula (I) is satisfied: 0.97≦Lhx / Lsx<1 (I) The secondary battery according to claim 6 or 7, which satisfies the relationship:

Images