Winding electrode

Abstract

To provide a wound electrode body that can improve heat dissipation on the inside of the winding. [Solution] The wound electrode body 10 is a wound electrode body 10 in which a first electrode 11A and a second electrode 11B having a different polarity from the first electrode 11A are wound in a flat shape via a separator 12. In the wound electrode body 10, the first electrode 11A includes a resin substrate, a conductive layer provided on the surface of the resin substrate, and a first active material layer 200A provided on the main surface of the conductive layer located on the side opposite to the side where the resin substrate is located relative to the conductive layer. The portion of the resin substrate located on the inside of the wound electrode body 10 has higher heat dissipation than the portion located on the outside of the wound electrode body 10.

Description

Technical Field

[0001] This disclosure relates to a wound electrode body.

Background Art

[0002] As a current collector used in a conventional wound electrode body, Japanese Patent Application Laid-Open No. 2019-186195 (Patent Document 1) discloses a structure including an insulating layer and a conductive layer, and provided with a plurality of through holes penetrating the insulating layer (resin foil) and the conductive layer in the current collector.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When forming a wound electrode body by winding a sheet-like electrode in which an active material layer is coated on a conductive layer provided on the surface of a resin foil (resin base material), since the resin foil has poor heat dissipation compared to a metal foil, heat easily accumulates inside the winding in the wound electrode body.

[0005] This disclosure has been made in view of the above problems, and an object of this disclosure is to provide a wound electrode body capable of enhancing heat dissipation inside the winding.

Means for Solving the Problems

[0006] The wound electrode body according to this disclosure is a wound electrode body in which a first electrode and a second electrode having a different polarity from the first electrode are wound in a flat shape with a separator in between. In the wound electrode body, the first electrode includes a resin substrate, a conductive layer provided on the surface of the resin substrate, and a first active material layer provided on the main surface of the conductive layer, which is located on the side opposite to the side where the resin substrate is located relative to the conductive layer. The portion of the resin substrate located on the inside of the wound electrode body has higher heat dissipation than the portion located on the outside of the wound electrode body.

[0007] According to the above configuration, the portion of the resin substrate located on the inside of the wound electrode body has higher heat dissipation properties than the portion located on the outside of the wound electrode body, thereby improving heat dissipation on the inside of the wound electrode body.

[0008] In the wound electrode body according to the above disclosure, the heat dissipation properties of the resin substrate may gradually or stepwise increase as it moves towards the inside of the wound electrode body.

[0009] According to the above configuration, heat dissipation can be gradually or stepwise increased toward the inside of the wound electrode body.

[0010] In the wound electrode body according to the above disclosure, the resin substrate may be composed of a first resin member and a second resin member having higher heat dissipation properties than the first resin member. When the direction parallel to the winding axis of the wound electrode body is defined as the width direction, the proportion of the second resin member in the width direction may increase as the resin substrate moves towards the inside of the wound electrode body, compared to the proportion of the first resin member in the width direction.

[0011] As shown in the above configuration, by adjusting the ratio of the first resin member and the second resin member that occupy the width direction of the resin substrate, the heat dissipation inside the winding can be improved.

[0012] In the wound electrode body according to the above disclosure, the resin substrate may be constructed by laminating a first resin member and a second resin member having higher heat dissipation properties than the first resin member. The resin substrate may have a proportion of the second resin member in the thickness direction that is greater than the proportion of the first resin member in the thickness direction as it moves towards the inside of the wound electrode body.

[0013] As shown in the above configuration, by adjusting the ratio of the first resin member and the second resin member that occupy the thickness direction of the resin substrate, the heat dissipation inside the winding can be improved.

[0014] In the wound electrode body according to the above disclosure, the resin substrate includes an inner end located at one end in the winding direction of the wound electrode body and an outer end located at the other end in the winding direction. The resin substrate may be composed of a first resin member located on the outer end side and a second resin member located on the inner end side, which has higher heat dissipation properties than the first resin member, joined together. The proportion of the second resin member arranged along the winding direction may be greater than the proportion of the first resin member arranged along the winding direction.

[0015] As shown in the above configuration, by adjusting the ratio of the first resin member and the second resin member along the winding direction, the heat dissipation inside the winding can be improved.

[0016] In the wound electrode body described above, the first resin member may be joined to the second resin member in a state in which it is embedded along the winding direction.

[0017] According to the above configuration, the first resin member bites into the second resin member, thereby stabilizing the bond between the first resin member and the second resin member.

[0018] In the wound electrode body based on the above disclosure, the second resin member may have self-extinguishing properties.

[0019] According to the above configuration, the wound electrode body can be provided with a self-extinguishing function, and the flame retardancy of the wound electrode body can be easily achieved.

Effects of the Invention

[0020] According to the present disclosure, a wound electrode body capable of enhancing the heat dissipation property on the inner side of the winding can be provided.

Brief Description of the Drawings

[0021] [Figure 1] It is a perspective view showing the battery according to Embodiment 1. [Figure 2] It is an exploded perspective view of the battery according to Embodiment 1. [Figure 3] It is a cross-sectional view of the battery in Fig. 1 seen in the direction of the arrow III-III. [Figure 4] It is a cross-sectional view of the electrode body in Fig. 3 seen in the direction of the arrow IV-IV. [Figure 5] It is a cross-sectional view of the electrode body in Fig. 3 seen in the direction of the arrow V-V. [Figure 6] It is a schematic cross-sectional view of the electrode body in Fig. 3 partially seen in the direction of the arrow VI-VI. [Figure 7] It is a developed view of the first electrode. [Figure 8] It is a partial cross-sectional view showing an enlarged view of region VIII of the first electrode in Fig. 5. [Figure 9] It is a partial cross-sectional view showing an enlarged view of region IX of the electrode body in Fig. 5. [Figure 10] It is a developed view of the resin base material according to Embodiment 1. [Figure 11] It is a developed view of the resin base material according to Embodiment 2. [Figure 12] It is a developed view of the resin base material according to Embodiment 3. [Figure 13] It is a developed view of the resin base material according to Embodiment 4. [Figure 14] It is a developed view of the resin base material according to Embodiment 5.

Modes for Carrying Out the Invention

[0022] Current collectors and batteries according to each embodiment of this disclosure will be described with reference to the drawings. In the drawings referred to below, the same or equivalent components are given the same numbers.

[0023] (Embodiment 1) Figure 1 is a perspective view showing a battery according to Embodiment 1. As shown in Figure 1, the battery 1 according to Embodiment 1 is a so-called prismatic battery. Battery 1 may be a rechargeable secondary battery such as a lithium-ion battery or a nickel-metal hydride battery. Battery 1 can be used, for example, as a cell included in an energy storage module mounted on an electric vehicle.

[0024] Figure 2 is an exploded perspective view of the battery according to Embodiment 1. Figure 3 is a cross-sectional view of the battery in Figure 1, viewed in the direction of the arrow III-III. As shown in Figures 1 to 3, the battery 1 according to Embodiment 1 of the present disclosure comprises a wound electrode body 10, a case 20, a first external terminal 30A, a second external terminal 30B, a first connecting member 40A, a second connecting member 40B, a first seal ring 50A, a second seal ring 50B, a first terminal support portion 60A, a second terminal support portion 60B, an insulating member 70, and a fuse protection portion 80. First, the components of the battery 1 other than the wound electrode body 10 will be described.

[0025] Case 20 is conductive. The conductive portion of Case 20 is made of a metal such as aluminum. Case 20 houses the wound electrode body 10. Case 20 also houses an electrolyte (not shown).

[0026] Case 20 includes a case body 21 and a lid 22. The case body 21 includes a bottom wall 21a and a peripheral wall 21b that rises from the bottom wall 21a.

[0027] The bottom wall 21a includes the bottom body 21aa, the pressure relief valve 21ab, the outer protective film 21ac, and the inner protective film 21ad. The peripheral wall 21b rises from the bottom body 21aa. The pressure relief valve 21ab is provided on the bottom body 21aa. The outer protective film 21ac covers the pressure relief valve 21ab from the outside. The inner protective film covers the pressure relief valve 21ab from the inside. The bottom body 21aa and the pressure relief valve 21ab are made of a metal such as aluminum.

[0028] An opening is formed at the upper end of the peripheral wall 21b. The peripheral wall 21b has a substantially rectangular outer shape when viewed from the direction of the opening (normal direction to the opening surface). The opening and the bottom wall 21a are aligned in a first direction D1. The first direction D1 may be the height direction or vertical direction of the battery 1. The peripheral wall 21b is made of a metal such as aluminum.

[0029] The lid 22 includes a lid body 22a, a sealing plug 22b, a plug cover 22c, and an insulating cover 22d.

[0030] The lid body 22a is joined to the peripheral wall 21b by welding or the like so as to close the opening in the peripheral wall 21b. The lid body 22a has a first connecting hole 22aa, a second connecting hole 22ab, and an electrolyte injection hole 22ac formed therein. The electrolyte injection hole 22ac is a through hole for injecting electrolyte into the case body 21 during the manufacturing process of the battery 1.

[0031] The sealing plug 22b seals the injection hole 22ac. The plug cover 22c covers the injection hole 22ac and the sealing plug 22b. The insulating cover 22d covers the injection hole 22ac, the sealing plug 22b, and the plug cover 22c.

[0032] The first external terminal 30A and the second external terminal 30B are provided so as to be exposed to the outside in the battery 1. The first connecting member 40A and the second connecting member 40B are conductive. At least a portion of the first connecting member 40A and the second connecting member 40B are located inside the case 20.

[0033] The first external terminal 30A or the first connecting member 40A is inserted through the first connecting hole 22aa. The first external terminal 30A and the first connecting member 40A are joined to each other. The first connecting member 40A is joined to the wound electrode body 10. As a result, the first external terminal 30A is electrically connected to the wound electrode body 10.

[0034] The second external terminal 30B or the second connecting member 40B is inserted through the second connecting hole 22ab. The second external terminal 30B and the second connecting member 40B are joined to each other. The second connecting member 40B is joined to the wound electrode body 10. As a result, the second external terminal 30B is electrically connected to the wound electrode body 10.

[0035] In this embodiment, the first external terminal 30A is the positive terminal, and the second external terminal 30B is the negative terminal. The first external terminal 30A and the second external terminal 30B are aligned in the second direction D2. The second direction D2 is perpendicular to the first direction D1.

[0036] The first seal ring 50A is provided along the first connecting hole 22aa. The first seal ring 50A is provided in the gap between the lid body 22a and the first external terminal 30A, and seals this gap. The second seal ring 50B is provided along the second connecting hole 22ab. The second seal ring 50B is provided in the gap between the lid body 22a and the second external terminal 30B, and seals this gap. The first seal ring 50A and the second seal ring 50B have electrical insulating properties.

[0037] The first terminal support portion 60A is locked to the lid body 22a. The first terminal support portion 60A supports the first external terminal 30A from the outer circumference of the first external terminal 30A. The first terminal support portion 60A includes a first locking ring 61A and a first covering ring 62A. The first locking ring 61A extends in an annular shape so as to surround the first connecting hole 22aa and is locked directly to the lid body 22a. The first covering ring 62A covers the first locking ring 61A. The first locking ring 61A supports the first external terminal 30A via the first covering ring 62A. The first covering ring 62A is made of a resin material that is electrically insulating or has relatively weak conductivity.

[0038] The second terminal support portion 60B is locked to the lid body 22a. The second terminal support portion 60B supports the second external terminal 30B from the outer circumference of the second external terminal 30B. The second terminal support portion 60B includes a second locking ring 61B and a second covering ring 62B. The second locking ring 61B extends in an annular shape so as to surround the second connecting hole 22ab and is locked directly to the lid body 22a. The second covering ring 62B covers the second locking ring 61B. The second locking ring 61B supports the second external terminal 30B via the second covering ring 62B. The second covering ring 62B is made of an electrically insulating resin material.

[0039] The insulating member 70 has electrical insulating properties. The insulating member 70 is positioned between the wound electrode body 10 and the case 20. The insulating member 70 electrically insulates the wound electrode body 10 and the case 20 from each other. The insulating member 70 includes an insulating bracket 71, a circumferential insulating portion 72, and a bottom insulating portion 73.

[0040] The insulating bracket 71 is positioned between the wound electrode body 10 and the lid body 22a. The insulating bracket 71 is relatively rigid and is in contact with both the wound electrode body 10 and the lid body 22a. As a result, the wound electrode body 10 is fixed to the case 20 in the first direction D1.

[0041] The circumferential insulating portion 72 is positioned between the wound electrode body 10 and the circumferential wall 21b. The wound electrode body 10 is made of a film-like material.

[0042] The bottom insulating portion 73 is positioned between the wound electrode body 10 and the bottom wall 21a. The bottom insulating portion 73 is made of a film-like material. In this embodiment, the bottom insulating portion 73 is adhered to the wound electrode body 10. Furthermore, the bottom insulating portion 73 covers only a portion of the bottom surface of the wound electrode body 10. The detailed configuration of the bottom insulating portion 73 will be described below together with the configuration of the wound electrode body 10.

[0043] As shown in Figure 2, the battery 1 according to this embodiment comprises a plurality of wound electrode bodies 10. Typically, the battery 1 comprises two wound electrode bodies 10. These wound electrode bodies 10 are aligned in a third direction D3. The third direction D3 is perpendicular to both the first direction D1 and the second direction D2. The circumferential insulating portion 72 may integrally cover the plurality of wound electrode bodies 10 so that they are fixed to each other. In this embodiment, the insulating member 70 also includes a plurality of bottom insulating portions 73 so as to correspond one-to-one with the plurality of wound electrode bodies 10.

[0044] In the following description, one of the multiple wound electrode bodies 10 will be explained. Note that each of the multiple wound electrode bodies 10 may have the configuration shown below.

[0045] Figure 4 is a cross-sectional view of the electrode body in Figure 3, viewed in the direction of the IV-IV arrow. Figure 5 is a cross-sectional view of the electrode body in Figure 3, viewed in the direction of the VV arrow. Figure 6 is a schematic cross-sectional view of the electrode body in Figure 3, partially viewed in the direction of the VI-VI arrow. As shown in Figures 2 to 6, the wound electrode body 10 includes a first electrode 11A, a second electrode 11B, a separator 12, and a tape member 13. The wound electrode body 10 is wound such that the first electrode 11A, the second electrode 11B, and the separator 12 surround the winding axis Z. In Figures 4 to 6, the separator 12 is schematically shown by a dashed line.

[0046] The first electrode 11A and the second electrode 11B have a sheet-like outer shape. The wound electrode body 10 is composed of a group of electrode plates in which the first electrode 11A and the second electrode 11B are wound around one or more separators 12.

[0047] In this embodiment, the first electrode 11A is the positive electrode and the second electrode 11B is the negative electrode. However, the first electrode 11A may be the negative electrode and the second electrode 11B may be the positive electrode.

[0048] The separator 12 is provided between the first electrode 11A and the second electrode 11B. The separator 12 separates the first electrode 11A and the second electrode 11B while allowing ions to move between them. The ions are, for example, lithium ions. The separator 12 has electrical insulating properties.

[0049] Of the first electrode 11A, the second electrode 11B, and the separator 12, the separator 12 is located on the innermost side with respect to the winding axis Z. Also, of the first electrode 11A, the second electrode 11B, and the separator 12, the separator 12 is located on the outermost side with respect to the winding axis Z. The outer edge of the separator 12 in the winding direction DR is fixed by a tape member 13 placed on the outer surface of the separator 12.

[0050] The separator 12 may contain, for example, a polyolefin resin. The separator 12 may be substantially made of a polyolefin resin. The polyolefin resin may contain, for example, at least one selected from the group consisting of polyethylene (PE) and polypropylene (PP).

[0051] The first electrode 11A includes a first current collector 100A, a first active material layer 200A, a first protective section 300, and a second protective section 400.

[0052] Figure 7 is an unfolded view of the first electrode. That is, Figure 7 shows the state before the first electrode 11A is wound. Figure 8 is a magnified partial cross-sectional view of region VIII of the first electrode in Figure 5. Figure 9 is a magnified partial cross-sectional view of region IX of the electrode body in Figure 5. As shown in Figures 5 to 9, the first current collector 100A includes a resin substrate 110, a first conductive layer 120, a second conductive layer 130, and a plurality of first tabs 150A.

[0053] The resin substrate 110 is made of an electrically insulating resin composition. Therefore, the first current collector 100A is a composite current collector consisting of a conductive member and an electrically insulating member. Furthermore, the resin substrate 110 is made of a material with higher rigidity than the separator 12. This allows the resin substrate 110 to be made relatively thin.

[0054] The resin substrate 110 includes a main body portion 111 and a plurality of protruding pieces 112. The orthogonal direction DO, which is perpendicular to the thickness direction DT of the main body portion 111, is substantially parallel to the first direction D1. That is, the main body portion 111 extends substantially parallel to the first direction D1. Each of the plurality of protruding pieces 112 protrudes from the main body portion 111 in the first direction. The plurality of protruding pieces 112 are spaced apart from each other in the winding direction DR. Each of the plurality of protruding pieces 112 is provided with a first tab 150A, which will be described later.

[0055] The thickness of the resin substrate 110 is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less, in order to reduce the overall thickness of the wound electrode body 10. The thickness of the resin substrate 110 is not particularly limited as long as it has the desired rigidity. The thickness of the resin substrate 110 may be, for example, 2 μm or more.

[0056] The first conductive layer 120 is in contact with the main body 111 on one side in the thickness direction DT. In this embodiment, the first conductive layer 120 is located on the side of the winding axis Z when viewed from the main body 111. Furthermore, the first conductive layer 120 is in contact with the main body 111 over its entire surface on one side in the thickness direction DT.

[0057] The second conductive layer 130 is in contact with the main body 111 on the other side in the thickness direction DT. In this embodiment, the second conductive layer 130 is located on the side opposite to the winding axis Z when viewed from the main body 111. Furthermore, the second conductive layer 130 is in contact with the main body 111 over its entire surface on the other side in the thickness direction DT.

[0058] The first conductive layer 120 and the second conductive layer 130 are each made of a metal. In this embodiment, the first conductive layer 120 and the second conductive layer 130 are made of a metal containing aluminum. As a result, the first current collector 100A can be suitably used as a positive electrode current collector. The first current collector 100A may also be a negative electrode current collector, and the first conductive layer 120 and the second conductive layer 130 may be made of a metal containing copper.

[0059] The thickness of the first conductive layer 120 and the thickness of the second conductive layer 130 are thinner than the thickness of the resin substrate 110. The thickness of the first conductive layer 120 and the second conductive layer 130 is, for example, 5 μm or less, more preferably 2 μm or less, and even more preferably 1 μm or less, in order to reduce the overall thickness of the wound electrode body 10. The thickness of the first conductive layer 120 and the second conductive layer 130 may be, for example, 0.1 μm or more, in order to prevent the electrical resistance of the first conductive layer 120 and the second conductive layer 130 from becoming too high.

[0060] The first conductive layer 120 and the second conductive layer 130 are provided, for example, by depositing a metal containing aluminum onto the main body 111. The first conductive layer 120 and the second conductive layer 130 may each be film-like members bonded to the main body 111.

[0061] Each of the multiple first tabs 150A is joined to the first conductive layer 120 and the second conductive layer 130, for example, by ultrasonic welding. Each of the multiple first tabs 150A extends from the resin substrate 110 along the projection direction from which the protruding piece 112 protrudes from the main body 111.

[0062] Multiple first tabs 150A are arranged so as to be aligned with each other in the third direction D3 (see Figure 5). Multiple first tabs 150A are joined to each other, for example by ultrasonic welding. Multiple first tabs 150A are joined to the first connecting member 40A, for example by ultrasonic welding (see Figures 2 and 3).

[0063] As shown in Figure 8, each of the multiple first tabs 150A includes a first foil portion 151 and a second foil portion 152.

[0064] The first foil portion 151 is located on the opposite side of the resin substrate 110 when viewed from the first conductive layer 120. The first foil portion 151 is joined to the first conductive layer 120. The second foil portion 152 is located on the opposite side of the resin substrate 110 when viewed from the second conductive layer 130. The second foil portion 152 is joined to the second conductive layer 130. The second foil portion 152 is joined to the first foil portion 151. These components are joined to each other, for example, by ultrasonic welding.

[0065] In this embodiment, the length of the first foil portion 151 in the orthogonal direction DO, perpendicular to the thickness direction DT, is longer than the length of the second foil portion 152 in the orthogonal direction DO. The first foil portion 151 is joined to the first connecting member 40A, while the second foil portion 152 is not joined to the first connecting member 40A. However, the configuration of the first tab 150A is not limited thereto. The first foil portion 151 or the second foil portion 152 may be joined to the first connecting member 40A. The length of the second foil portion 152 in the orthogonal direction DO may be longer than the length of the first foil portion 151 in the orthogonal direction DO.

[0066] The first active material layer 200A is laminated on the first conductive layer 120. The first active material layer 200A is a positive electrode active material layer, but may also be a negative electrode active material layer. In this embodiment, the first active material layer 200A is also laminated on the second conductive layer 130. The first active material layer 200A includes a first inner active material layer 210A and a first outer active material layer 220A. The first inner active material layer 210A is laminated on the first conductive layer 120. The first outer active material layer 220A is laminated on the second conductive layer 130.

[0067] The upper edge of the first active material layer 200A is separated from each of the multiple first tabs 150A. The upper edge of the first inner active material layer 210A is separated from each of the first foil portions 151 of the multiple first tabs 150A. The upper edge of the first outer active material layer 220A is separated from each of the second foil portions 152 of the multiple first tabs 150A.

[0068] As shown in Figure 9, the lower edge of the first active material layer 200A is aligned with the lower edge of the main body 111.

[0069] Furthermore, the separator 12 is laminated on the first active material layer 200A in the radial direction centered on the winding axis Z. The separator 12 is laminated on the first inner active material layer 210A in the same radial direction. The separator 12 is also laminated on the first outer active material layer 220A in the same radial direction.

[0070] The first protective part 300 has electrical insulating properties and is made of, for example, ceramic. The first protective part 300 covers the upper part of the first active material layer 200A. The first protective part 300 further covers the first current collector 100A between the first tab 150A and the first active material layer 200A.

[0071] The first protective section 300 includes a first inner protective section 310 and a first outer protective section 320. The first inner protective section 310 covers the upper part of the first inner active material layer 210A. The first inner protective section 310 covers the first conductive layer 120 between the first foil section 151 and the first inner active material layer 210A. The first outer protective section 320 covers the upper part of the first outer active material layer 220A. The first outer protective section 320 covers the second conductive layer 130 between itself and the first outer active material layer 220A.

[0072] The second protective part 400 has electrical insulating properties and is made of, for example, ceramic. The second protective part 400 covers the lower part of the first active material layer 200A. The second protective part 400 also covers the lower end surface of the resin substrate 110.

[0073] The second protective section 400 includes a second inner protective section 410 and a second outer protective section 420. The second inner protective section 410 covers the lower part of the first inner active material layer 210A. The second outer protective section 420 covers the lower part of the first outer active material layer 220A. The first electrode 11A does not necessarily include the second protective section 400.

[0074] As shown in Figures 4 to 6 and Figure 9, the second electrode 11B is laminated on the first active material layer 200A via the separator 12 in the radial direction. More specifically, the second electrode 11B is laminated on the first inner active material layer 210A via the separator 12, and is also laminated on the first outer active material layer 220A via the separator 12.

[0075] The second electrode 11B includes a second current collector 100B and a second active material layer 200B. The second current collector 100B includes a conductive support portion 140 and a plurality of second tabs 150B (see Figure 6). The conductive support portion 140 extends along the orthogonal direction DO (first direction D1). The plurality of second tabs 150B extend from the upper end of the conductive support portion 140. The plurality of second tabs 150B are joined to each other by ultrasonic welding and are also joined to the second connecting member 40B (see Figures 2 and 3).

[0076] The multiple second tabs 150B and conductive support portion 140 are made of a single integrated material, for example, metal foil. In this embodiment, the multiple second tabs 150B and conductive support portion 140 are made of a metal including copper, for example. This allows the second current collector 100B to be suitably used as a negative electrode current collector. If the first current collector 100A is a negative electrode current collector, the multiple second tabs 150B and conductive support portion 140 may be made of a metal including aluminum.

[0077] The second active material layer 200B is laminated on both sides of the conductive support portion 140 of the second current collector 100B. In this embodiment, the second electrode 11B is the negative electrode. Therefore, the second active material layer 200B is the negative electrode active material layer. Also, as shown in Figure 9, the edge of the second active material layer 200B in the first direction D1 is located ahead of the edge of the first active material layer 200A. Therefore, the edge of the second electrode 11B in the first direction D1 is located ahead of the edge of the first conductive layer 120, the second conductive layer 130, and the edge of the first active material layer 200A. The second active material layer 200B may also be the positive electrode active material layer.

[0078] Figure 10 is an exploded view of the resin substrate according to Embodiment 1. The detailed structure of the resin substrate 110 according to Embodiment 1 will be described with reference to Figure 10.

[0079] As shown in Figure 10, the resin substrate 110 has a first resin member 110A and a second resin member 110B. The second resin member 110B has higher heat dissipation properties than the first resin member 110A. For example, the first resin member 110A can be a resin member such as PPS (polyphenylene sulfide) or PET (polyethylene terephthalate). As the second resin member 110B, for example, a resin such as PPE (polyphenylene ether) or polyimide can be used. PPE has high self-extinguishing properties.

[0080] The resin substrate 110 has an outer end 110a and an inner end 110b at both ends in the winding direction DR. The outer end 110a constitutes the end located on the outside in the winding direction when the resin substrate 110 is wound. The inner end 110b constitutes the end located on the inside in the winding direction when the resin substrate 110 is wound.

[0081] The resin substrate 110 has higher heat dissipation properties in the portion located inside the wound electrode body 10 than in the portion located outside the wound electrode body 10.

[0082] Specifically, when the direction parallel to the winding axis of the wound electrode body 10 is defined as the width direction of the resin substrate 110, the proportion of the second resin member in the width direction of the resin substrate 110 becomes larger than the proportion of the first resin member 110A in the width direction as it moves towards the inside of the wound electrode body 10. The width direction is parallel to the first direction D1.

[0083] The outer end 110a and inner end 110b described above each have one end and the other end on one side and the other side in the width direction, respectively.

[0084] In the unfolded state of the resin substrate 110, the region is divided into two parts along a diagonal line connecting one end of the outer end 110a to the other end of the inner end 110b. The region located on one end in the width direction is composed of the second resin member 110B, and the region located on the other end in the width direction is composed of the first resin member 110A. The first resin member 110A and the second resin member 110B are joined together, for example, by welding.

[0085] With the resin substrate 110 configured in this way, in the wound electrode body 10 with the resin substrate 110 wound around it, the proportion of the second resin member 110B located on the inside in the winding direction is greater than the proportion of the first resin member 110A located on the inside in the winding direction. On the other hand, in the wound electrode body 10, the proportion of the first resin member 110A located on the outside in the winding direction is greater than the proportion of the second resin member 110B located on the outside in the winding direction. As a result, the heat dissipation performance of the portion located on the inside of the wound electrode body 10 can be made higher than that of the portion located on the outside of the wound electrode body 10.

[0086] Furthermore, by arranging the second resin member 110B as described above, all of the multiple protruding pieces 112 can be made of the second resin member 110B, which has high heat dissipation properties. This also improves the heat dissipation from the protruding pieces 112.

[0087] Furthermore, by making the second resin member 110B a resin member with high self-extinguishing properties, the wound electrode body 10 can be given a self-extinguishing function, and the flame retardancy of the wound electrode body 10 can be easily achieved.

[0088] In the above description, an example was given in which the boundary between the first resin member 110A and the second resin member 110B is straight, and the heat dissipation gradually increases towards the inside of the wound electrode body 10, but the invention is not limited to this. The boundary between the first resin member 110A and the second resin member 110B may be stepped, with the number of steps increasing from the inner end 110b to the outer end 110a, and the heat dissipation may increase in stages towards the inside of the wound electrode body 10.

[0089] (Embodiment 2) Figure 11 is an unfolded view of the resin substrate according to Embodiment 2. The resin substrate 110X according to Embodiment 2 will be described with reference to Figure 11.

[0090] The resin substrate 110X according to Embodiment 2 differs from the resin substrate 110 according to Embodiment 1 in the arrangement of the first resin member 110A and the second resin member 110B. The other configurations are substantially the same. Furthermore, the resin substrate 110X according to Embodiment 2 can be used in place of the resin substrate 110 according to Embodiment 1 for the wound electrode body 10.

[0091] In this embodiment as well, the resin substrate 110X is configured such that the portion located inside the wound electrode body 10 has higher heat dissipation properties than the portion located outside the wound electrode body 10.

[0092] In the resin substrate 110X, the first resin member 110A is positioned on one side in the winding direction DR, and the second resin member 110B is positioned on the other side in the winding direction DR. That is, the first resin member 110A is located on the outer end 110a side, and the second resin member 110B is located on the inner end 110b side.

[0093] The proportion of the second resin member 110B arranged along the winding direction DR is greater than the proportion of the first resin member 110A arranged along the winding direction DR. Specifically, the length of the first resin member 110A along the winding direction DR is shorter than the length of the second resin member 110B along the winding direction DR. The first resin member 110A and the second resin member 110B are joined together along a direction parallel to the winding axis.

[0094] As described above, the resin substrate 110X is configured such that, even in the wound electrode body 10 with the resin substrate 110X wound around it, the heat dissipation of the portion located on the inside of the wound electrode body 10 can be made higher than the heat dissipation of the portion located on the outside of the wound electrode body 10.

[0095] Furthermore, by arranging the second resin member 110B as described above, the proportion of the multiple protruding pieces 112 that are composed of the second resin member 110B, which has high heat dissipation properties, can be increased. This also improves the heat dissipation from the protruding pieces 112.

[0096] (Embodiment 3) Figure 12 is an unfolded view of the resin substrate according to Embodiment 3. The resin substrate 110Y according to Embodiment 3 will be described with reference to Figure 12.

[0097] The resin substrate 110Y according to Embodiment 3 differs from the resin substrate 110X according to Embodiment 2 in the joining method (more specifically, the shape of the joining portion) of the first resin member 110A and the second resin member 110B. The other configurations are substantially the same. Furthermore, the resin substrate 110Y according to Embodiment 3 can be used in place of the resin substrate 110 according to Embodiment 1 in the wound electrode body 10.

[0098] In the resin substrate 110Y according to Embodiment 3, the first resin member 110A is located on the outer end 110a side, and the second resin member 110B is located on the inner end 110b side. Furthermore, the proportion of the second resin member 110B arranged along the winding direction DR is larger than that of the first resin member 110A arranged along the winding direction DR.

[0099] In Embodiment 3, the first resin member 110A is joined to the second resin member 110B in a state where it is embedded in the winding direction DR. This makes it possible to stabilize the joint between the first resin member 110A and the second resin member 110B.

[0100] (Embodiment 4) Figure 13 is an unfolded view of the resin substrate according to Embodiment 4. The resin substrate 110Z according to Embodiment 34 will be described with reference to Figure 13.

[0101] The resin substrate 110Z according to Embodiment 4 differs from the resin substrate 110 according to Embodiment 1 in that it is constructed by laminating a first resin member 110A and a second resin member 110B. Furthermore, the resin substrate 110Z according to Embodiment 4 can be used in place of the resin substrate 110 according to Embodiment 1 for the wound electrode body 10.

[0102] In this embodiment as well, the resin substrate 110Z is configured such that the portion located inside the wound electrode body 10 has higher heat dissipation properties than the portion located outside the wound electrode body 10.

[0103] Specifically, as the resin substrate 110Z moves towards the inside of the wound electrode body, the proportion of the second resin member 110B in the thickness direction DT becomes larger than the proportion of the first resin member 110A in the thickness direction DT.

[0104] In its unfolded state, the resin substrate 110Z has one end 110c and the other end 110d on one and the other side in the thickness direction DT, respectively. In the unfolded state, the region is divided into two parts along a diagonal line connecting the other end 110d in the thickness direction DT located at the outer end 110a to the one end 110c in the thickness direction DT located at the inner end 110b. The region located on one side in the thickness direction DT is composed of the first resin member 110A. The region located on the other side in the thickness direction DT is composed of the second resin member 110B.

[0105] Even in this configuration, the heat dissipation performance of the portion located on the inside of the wound electrode body 10 can be made higher than that of the portion located on the outside of the wound electrode body 10, even in the wound electrode body 10 with the resin substrate 110Z wound around it.

[0106] (Embodiment 5) Figure 14 is an exploded view of the resin substrate according to Embodiment 5. The resin substrate 110W according to Embodiment 4 will be described with reference to Figure 14.

[0107] The resin substrate 110W according to Embodiment 5 differs from the resin substrate 110 according to Embodiment 1 in that it controls heat dissipation by adjusting the amount of filler 115 dispersed in a single resin member. The resin substrate 110W according to Embodiment 5 can be used in place of the resin substrate 110 according to Embodiment 1 for the wound electrode body 10.

[0108] As shown in Figure 14, the amount of filler 115 dispersed is greater on the inside of the wound electrode body 10 than on the outside. As a result, the heat dissipation of the portion located on the inside of the wound electrode body 10 is higher than that of the portion located on the outside of the wound electrode body 10. The amount of filler 115 dispersed may gradually increase towards the inside of the wound electrode body 10, or it may increase in steps. For example, metal particles such as aluminum can be used as the filler 115. Even with the above configuration, substantially the same effects as in Embodiment 1 can be obtained.

[0109] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure is indicated by the claims rather than the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended. [Explanation of Symbols]

[0110] 1 Battery, 10 Winding electrode body, 11A First electrode, 11B Second electrode, 12 Separator, 13 Tape material, 20 Case, 21 Case body, 21a Bottom wall, 21aa Bottom body, 21ab Pressure relief valve, 21ad Inner protective film, 21b Peripheral wall, 22 Lid, 22a Lid body, 22aa First connecting hole, 22ab Second connecting hole, 22b Sealing plug, 22c Plug cover, 22d Insulating cover, 30A First external terminal, 30B Second external terminal, 40A First connecting member, 40B Second connecting member, 50A First sealing ring, 50B Second sealing ring, 60A First terminal support part, 60B Second terminal support part, 61A First locking ring, 61B Second locking ring, 62A First covering ring, 62B Second covering ring, 70 Insulating material, 71 Insulating bracket, 72 Peripheral insulating part, 73 Bottom insulating part, 80 Fuse protection part, 100A First current collector, 100B Second current collector, 110, 110W, 110X, 110Y, 110Z Resin substrate, 110A First resin member, 110B Second resin member, 110a Outer end, 110b Inner end, 110c One end, 110d Other end, 111 Main body part, 112 Protruding piece part, 115 Filler, 120 First conductive layer, 130 Second conductive layer, 140 Conductive support part, 150A First tab, 150B Second tab, 151 First foil part, 152 Second foil part, 200A First active material layer, 200B Second active material layer, 210A First inner active material layer, 220A First outer active material layer, 300 First protective section, 310; first inner protective section, 320; first outer protective section, 400; second protective section, 410; second inner protective section, 420; second outer protective section; D1 first direction; D2 second direction; D3 third direction; DO orthogonal direction; DR winding direction; DT thickness direction; IX, VIII region; Z winding axis.

Claims

1. A wound electrode body in which a first electrode and a second electrode having a different polarity from the first electrode are wound in a flattened shape via a separator, The first electrode includes a resin substrate, a conductive layer provided on the surface of the resin substrate, and a first active material layer provided on the main surface of the conductive layer, which is located on the side opposite to the side where the resin substrate is located relative to the conductive layer. A wound electrode body wherein the portion of the resin substrate located on the inside of the wound electrode body has higher heat dissipation properties than the portion located on the outside of the wound electrode body.

2. The heat dissipation properties of the resin substrate gradually or stepwise increase towards the inside of the wound electrode body, as described in claim 1.

3. The resin substrate is composed of a first resin member and a second resin member having higher heat dissipation properties than the first resin member. The winding electrode body according to claim 1, wherein, when the direction parallel to the winding axis of the winding electrode body is defined as the width direction, the proportion of the second resin member in the width direction of the resin substrate becomes larger than the proportion of the first resin member in the width direction as it moves towards the inside of the winding electrode body.

4. The resin substrate is constructed by laminating a first resin member and a second resin member having higher heat dissipation properties than the first resin member. The wound electrode body according to claim 1, wherein, as the resin substrate moves toward the inside of the wound electrode body, the proportion of the second resin member in the thickness direction becomes larger than the proportion of the first resin member in the thickness direction.

5. The resin substrate includes an inner end located at one end in the winding direction of the wound electrode body and an outer end located at the other end in the winding direction. The resin substrate is constructed by joining together a first resin member located on the outer end side and a second resin member located on the inner end side, which has higher heat dissipation properties than the first resin member. The wound electrode body according to claim 1, wherein the proportion of the second resin member arranged along the winding direction is greater than the proportion of the first resin member arranged along the winding direction.

6. The wound electrode body according to claim 5, wherein the first resin member is joined to the second resin member in a state in which it bites into the winding direction.

7. The second resin member is a self-extinguishing wound electrode body according to any one of claims 3 to 6.

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