Winding electrode

Abstract

To provide a wound electrode body that can suppress damage to the curved portion. [Solution] A winding electrode body 10 is provided in which a positive electrode 11 and a negative electrode 12 are wound in a flat shape via a separator 13, and has a pair of flat portions 91 facing each other with respect to the winding center, and a pair of curved portions 92 connecting the ends of the pair of flat portions 91, wherein the positive electrode 11 includes a first base material in which a first metal foil 111 and a first resin member 112 are alternately joined along the winding direction of the winding electrode body 10, and the negative electrode 12 includes a second base material in which a second metal foil 121 and a second resin member 122 are alternately joined along the winding direction, in each of the pair of flat portions 91 the first metal foil 111 and the second metal foil 121 are alternately arranged in the direction in which the pair of flat portions 91 face each other, and in each of the pair of curved portions 92 the first resin member 112 and the second resin member 122 are alternately arranged in the radial direction of the winding electrode body 10.

Description

Technical Field

[0001] The present disclosure relates to a wound electrode body.

Background Art

[0002] As a conventional electrode body, Japanese Patent Application Laid-Open No. 2016-042433 (Patent Document 1) discloses a wound electrode body in which a separator is interposed between a positive electrode having a first metal foil and a positive electrode active material layer formed on the first metal foil, and a negative electrode having a second metal foil and a negative electrode active material layer formed on the second metal foil, and the positive electrode and the negative electrode are wound.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the wound electrode body, a pair of flat portions facing each other across the winding center and a pair of curved portions connecting the ends of the pair of flat portions are formed. In the wound electrode, the pair of curved portions are maintained in a bent state, and a higher stress is applied to the pair of curved portions than to the pair of flat portions.

[0005] The present disclosure has been made in view of the above problems, and an object of the present disclosure is to provide a wound electrode body capable of suppressing breakage of the curved portion.

Means for Solving the Problems

[0006] The wound electrode body according to this disclosure is a wound electrode body in which a positive electrode and a negative electrode are wound in a flat shape via a separator, and has a pair of flat portions facing each other with respect to the winding center, and a pair of curved portions connecting the ends of the pair of flat portions. In the wound electrode body, the positive electrode includes a first base material in which a first metal foil and a first resin member are alternately joined along the winding direction of the wound electrode body. The negative electrode includes a second base material in which a second metal foil and a second resin member are alternately joined along the winding direction. In each of the pair of flat portions, the first metal foil and the second metal foil are alternately arranged in the direction in which the pair of flat portions face each other. In each of the pair of curved portions, the first resin member and the second resin member are alternately arranged in the radial direction of the wound electrode body.

[0007] According to the above configuration, in each of the pair of curved sections, the first resin member and the second resin member are alternately arranged in the radial direction of the wound electrode body. Compared to a configuration in which metal foil is arranged in the curved section, the curved section is more prone to bending deformation and less prone to breakage. As a result, even when high stress is applied to the curved section, damage to the curved section can be suppressed.

[0008] In the wound electrode body according to the above disclosure, the first boundary, which is the boundary between the first metal foil and the first resin member, in a cross section perpendicular to the winding axis of the wound electrode body, may be located at the boundary between the pair of flat portions and the pair of curved portions. The second boundary, which is the boundary between the second metal foil and the second resin member, may be located at the boundary between the pair of flat portions and the pair of curved portions.

[0009] With the above configuration, the entire curved section is made of resin material. This further suppresses damage to the curved section.

[0010] In the wound electrode body according to the above disclosure, in the cross section perpendicular to the winding axis, the first boundary and the second boundary at each boundary between the pair of flat portions and the pair of curved portions may be arranged alternately in the direction in which the first metal foil and the second metal foil are arranged alternately.

[0011] In the above configuration, the entire curved section is made of resin material. This further suppresses damage to the curved section.

[0012] In the wound electrode body according to the present disclosure described above, when the direction perpendicular to the direction in which the winding axis and the pair of flat portions face each other is defined as the width direction, the first boundary and the second boundary may be alternately arranged in the cross section perpendicular to the winding axis, such that at each boundary between the pair of flat portions and the pair of curved portions, the boundary moves inward in the width direction as the winding electrode body moves from the outer circumference to the inner circumference.

[0013] According to the above configuration, the curved portion can be formed in a fan shape, making it easier to deform. This prevents the curved portion from breaking when stress is applied to it.

[0014] In the wound electrode body according to the above disclosure, when the width direction is defined as the direction perpendicular to the direction in which the winding axis and the pair of flat portions face each other, the first boundary and the second boundary may be alternately arranged in the cross section perpendicular to the winding axis, such that at each boundary between the pair of flat portions and the pair of curved portions, the first boundary and the second boundary move outward in the width direction as the winding electrode body moves from the outer circumference to the inner circumference.

[0015] According to the above configuration, in a pair of flat sections, the proportion (length) of metal foil placed inside the wound electrode body is greater than the proportion (length) of metal foil placed outside the wound electrode body.

[0016] Generally, heat tends to accumulate inside wound electrode bodies, but by using the above configuration, the proportion of metal foil inside the wound electrode body can be increased, thereby improving heat dissipation.

[0017] In the wound electrode body according to the above disclosure, the thickness of the first resin member may be thinner than that of the first metal foil.

[0018] According to the above configuration, since the thickness of the first resin member is thinner than that of the first metal foil, the curved portion is more easily bent.

[0019] In the wound electrode body based on the present disclosure, the thickness of the second resin member may be thinner than that of the second metal foil.

[0020] According to the above configuration, since the thickness of the second resin member is thinner than that of the second metal foil, the curved portion is more easily bent.

Advantages of the Invention

[0021] According to the present disclosure, it is possible to provide a wound electrode body capable of suppressing damage to the curved portion.

Brief Description of the Drawings

[0022] [Figure 1] It is a perspective view showing a 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 shown in FIG. 1 as viewed in the direction of the arrow III-III. [Figure 4] It is a cross-sectional view of the wound electrode body shown in FIG. 3 as viewed in the direction of the arrow IV-IV. [Figure 5] It is a cross-sectional view of the positive electrode of the wound electrode body shown in FIG. 3 in a developed state. [Figure 6] It is a cross-sectional view of the negative electrode of the wound electrode body shown in FIG. 3 in a developed state. [Figure 7] It is a cross-sectional view of the wound electrode body according to Embodiment 2. [Figure 8] It is a cross-sectional view of the wound electrode body according to Embodiment 3.

Modes for Carrying Out the Invention

[0023] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the embodiments shown below, the same or common parts are denoted by the same reference numerals in the drawings, and the description thereof will not be repeated.

[0024] (Embodiment 1) Figure 1 is a perspective view showing a battery according to Embodiment 1. The battery 1 according to Embodiment 1 will be described with reference to Figure 1.

[0025] As shown in Figure 1, battery 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 installed in an electric vehicle.

[0026] Figure 2 is an exploded perspective view of the battery according to Embodiment 1. Figure 3 is a cross-sectional view of the battery of Figure 1, viewed in the direction of the arrow III-III.

[0027] As shown in Figures 1 to 3, the battery 1 comprises a plurality of wound electrode bodies 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 sealing ring 50A, a second sealing ring 50B, a first terminal support part 60A, a second terminal support part 60B, an insulating member 70, and a fuse protection part 80. First, the components of the battery 1 other than the wound electrode bodies 10 will be described.

[0028] 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).

[0029] 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.

[0030] 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.

[0031] 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.

[0032] The lid 22 includes a lid body 22a, a sealing plug 22b, a plug cover 22c, and an insulating cover 22d.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] The insulating member 70 has electrical insulating properties. The insulating member 70 is positioned between the multiple wound electrode bodies 10 and the case 20. The insulating member 70 electrically insulates the multiple wound electrode bodies 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.

[0043] The insulating bracket 71 is positioned between the multiple wound electrode bodies 10 and the lid body 22a. The insulating bracket 71 is relatively rigid and is in contact with both the wound electrode bodies 10 and the lid body 22a. As a result, the wound electrode bodies 10 are fixed to the case 20 in the first direction D1.

[0044] The circumferential insulating portion 72 is positioned between the multiple wound electrode bodies 10 and the circumferential wall 21b. The circumferential insulating portion 72 is made of a film-like material.

[0045] The bottom insulating portion 73 is positioned between each 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. However, the bottom insulating portion 73 may cover the entire bottom surface.

[0046] The wound electrode body 10 is provided with a plurality of first tabs 150A and a plurality of second tabs 150B. One end of the plurality of first tabs 150A is connected to the first metal foil 111 (see Figure 4) of the positive electrode 11 (see Figure 4), which will be described later. The other end of the plurality of first tabs 150A is joined to the first connecting member 40A by ultrasonic welding or the like.

[0047] One end of each of the multiple second tabs 150B is connected to the second metal foil 121 (see Figure 4) of the negative electrode 12 (see Figure 4), which will be described later. The other end of each of the multiple second tabs 150B is joined to the second connecting member 40B described above by ultrasonic welding or the like.

[0048] 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.

[0049] Figure 4 is a cross-sectional view of the wound electrode body shown in Figure 3, viewed in the direction of the arrow along the line IV-IV. Referring to Figure 4, the details of the wound electrode body 10 according to Embodiment 1 will be described.

[0050] As shown in Figure 4, the wound electrode body 10 is constructed by winding a positive electrode 11 and a negative electrode 12 in a flattened shape via a separator 13. Separators 13 are positioned at the innermost and outermost ends of the wound electrode body 10. The outer edge of the separator 13 in the winding direction DR is fixed by a tape member 15 positioned on the outer surface of the separator 13.

[0051] The separator 13 is provided between the positive electrode 11 and the negative electrode 12. The separator 13 separates the positive electrode 11 and the negative electrode 12 while allowing ions to move between them. The ions are, for example, lithium ions. The separator 13 has electrical insulating properties.

[0052] The separator 13 may contain, for example, a polyolefin resin. The separator 13 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).

[0053] The wound electrode body 10 has as its constituent parts a pair of flat portions 91 facing each other with the winding center in between, and a pair of curved portions 92 connecting the ends of the pair of flat portions.

[0054] The pair of flat portions 91 have a thin plate shape parallel to the winding axis Z. In this embodiment, the pair of flat portions 91 face a third direction D3 perpendicular to the winding axis Z direction. The pair of curved portions 92 constitute both ends of the wound electrode body 10 in a direction perpendicular to both the thickness direction (third direction D3) of the flat portions 91 and the winding axis Z direction. Specifically, the pair of curved portions 92 constitute both ends of the wound electrode body 10 in the second direction D2. Each of the pair of curved portions 92 bulges outward in the second direction D2. Each of the pair of curved portions 92 is curved so as to be convex outward in the second direction D2.

[0055] Figure 5 is a cross-sectional view of the positive electrode of the wound electrode body shown in Figure 3 in an unfolded state. As shown in Figure 5, the positive electrode 11 has a sheet shape that extends in the longitudinal direction when unfolded. The longitudinal direction is the winding direction of the wound electrode body 10 when the positive electrode 11 is wound. The positive electrode 11 includes a first base material 110 and a positive electrode active material layer 113 provided on the first base material 110. In the unfolded state, the first base material 110 includes first metal foils 111 and first resin members 112 that are alternately joined in the longitudinal direction. The boundaries between the first metal foils 111 and the first resin members 112 are shown as first boundaries P1 in Figure 5. The thickness of the first resin member 112 in the thickness direction DT may be thinner than that of the first metal foils 111. The thickness direction DT of the first base material 110 is substantially parallel to the third direction D3 in the flat portion 91.

[0056] The first metal foil 111 can be, for example, a metal component containing aluminum. The first resin component 112 can be, for example, polyethylene (PE), polypropylene (PP), PPS (polyphenylene sulfide), or PET (polyethylene terephthalate). The first resin component 112 may have insulating properties. To reduce the electrical resistance of the first substrate 110, the first resin component 112 may contain conductive fine particles.

[0057] The first metal foil 111 and the first resin member 112 have a first main surface and a second main surface aligned in the thickness direction DT. The positive electrode active material layer 113 is provided on the first and second main surfaces of the first metal foil 111 and the first and second main surfaces of the first resin member 112. Known materials can be used as the positive electrode active material layer 113.

[0058] Figure 6 is a cross-sectional view of the negative electrode of the wound electrode body shown in Figure 3 in an unfolded state. As shown in Figure 6, the negative electrode 12 has a sheet shape that extends in the longitudinal direction when unfolded. The longitudinal direction is the winding direction of the wound electrode body 10 when the negative electrode 12 is wound. The negative electrode 12 includes a second base material 120 and a negative electrode active material layer 123 provided on the second base material 120. In the unfolded state, the second base material 120 includes a second metal foil 121 and a second resin member 122 that are alternately joined in the longitudinal direction. The boundaries between the second metal foil 121 and the second resin member 122 are shown as second boundaries P2 in Figure 5. The thickness of the second resin member 122 in the thickness direction DT may be thinner than that of the second metal foil 121. The thickness direction DT of the second base material 120 is substantially parallel to the third direction D3 in the flat portion 91.

[0059] The second metal foil 121 can be, for example, a metal component containing copper. The second resin component 122 can be, for example, polyethylene (PE), polypropylene (PP), PPS (polyphenylene sulfide), or PET (polyethylene terephthalate). The second resin component 122 may have insulating properties. To reduce the electrical resistance of the first substrate 110, the second resin component 122 may contain conductive fine particles.

[0060] The second metal foil 121 and the second resin member 122 have a first main surface and a second main surface aligned in the thickness direction DT. The negative electrode active material layer 123 is provided on the first and second main surfaces of the second metal foil 121 and on the first and second main surfaces of the second resin member 122. Known materials can be used as the negative electrode active material layer 123.

[0061] Referring to Figures 4 to 6, in the wound electrode body 10, the first base material 110 of the positive electrode 11 has the first metal foil 111 and the first resin member 112 alternately joined along the winding direction. Similarly, in the wound electrode body 10, the second base material 120 of the negative electrode 12 has the second metal foil 121 and the second resin member 122 alternately joined along the winding direction.

[0062] In each of the pair of flat sections 91 described above, the first metal foil 111 and the second metal foil 121 are arranged alternately in the direction in which the pair of flat sections face each other. In each of the pair of curved sections 92, the first resin member 112 and the second resin member 122 are arranged alternately in the radial direction of the wound electrode body 10.

[0063] As the first resin member 112 and the second resin member 122 are arranged alternately in the radial direction in the curved portion 92, the curved portion 92 is more prone to bending and deformation and less prone to breakage compared to a configuration in which metal foil is arranged in the curved portion 92. This makes it possible to suppress damage to the curved portion 92 even when high stress is applied to it.

[0064] Furthermore, in a cross-section perpendicular to the winding axis Z of the wound electrode body 10, the first boundary P1, which is the boundary between the first metal foil 111 and the first resin member 112, is located at the boundaries B1 and B2 between a pair of flat sections 91 and a pair of curved sections 92, and the second boundary P2, which is the boundary between the second metal foil 121 and the second resin member 122, is located at the boundary between a pair of flat sections 91 and a pair of curved sections 92. As a result, the entire curved section 92 is made of resin material. This further suppresses damage to the curved section 92.

[0065] More specifically, at each boundary between the pair of flat sections 91 and the pair of curved sections 92, the first boundary P1 and the second boundary P2 are arranged alternately in the direction in which the first metal foil 111 and the second metal foil 121 are arranged alternately from the inner circumference to the outer circumference of the wound electrode body 10. That is, each boundary between the pair of flat sections 91 and the pair of curved sections 92 is parallel to the third direction D3.

[0066] Even in this configuration, the entire curved portion 92 is made of resin material. This further suppresses damage to the curved portion 92.

[0067] Furthermore, because the thickness of the first resin member 112 is thinner than the thickness of the first metal foil 111, the curved portion 92 becomes easier to bend. Also, because the thickness of the second resin member 122 is thinner than the thickness of the second metal foil 121, the curved portion 92 becomes easier to bend. This further suppresses damage to the curved portion 92.

[0068] (Embodiment 2) Figure 7 is a cross-sectional view of the wound electrode body according to Embodiment 2. Note that Figure 7 is a cross-sectional view corresponding to the battery shown in Figure 1 in Embodiment 1, viewed in the direction of the arrow III-III. The wound electrode body 10X according to Embodiment 2 will be described with reference to Figure 7.

[0069] As shown in Figure 7, the wound electrode body 10X according to Embodiment 2 differs from the wound electrode body 10 according to Embodiment 1 in that the boundaries between the pair of flat portions 91 and the pair of curved portions 92 are in different positions. The other configurations are substantially the same.

[0070] When the width direction is defined as the direction in which the pair of flat portions 91 face each other and the direction perpendicular to the winding axis Z of the wound electrode body 10, in a cross section perpendicular to the winding axis Z of the wound electrode body 10, the boundaries between the pair of flat portions 91 and the pair of curved portions 92 are inclined inward in the width direction as they move from the outer circumference to the inner circumference of the wound electrode body 10. The width direction is parallel to the second direction D2.

[0071] In a cross-section perpendicular to the winding axis Z of the wound electrode body 10, the first boundary P1 and the second boundary P2 are alternately arranged at each boundary between the pair of flat portions 91 and the pair of curved portions 92, such that they move inward in the width direction as you move from the outer circumference to the inner circumference of the wound electrode body 10X.

[0072] Even when configured as described above, the wound electrode body 10X according to Embodiment 2 provides substantially the same effects as that of Embodiment 1. In addition, because the boundary positions of the pair of flat portions 91 and the pair of curved portions 92 are as described above, the curved portions 92 can be formed in a fan shape, making the curved portions 92 more easily deformable. This makes it possible to suppress the bending of the curved portions 92 when stress is applied to them.

[0073] (Embodiment 3) Figure 8 is a cross-sectional view of the wound electrode body according to Embodiment 3. Note that Figure 8 is a cross-sectional view corresponding to the battery shown in Figure 1 in Embodiment 1, viewed in the direction of the arrow III-III. The wound electrode body 10Y according to Embodiment 3 will be described with reference to Figure 8.

[0074] As shown in Figure 8, the wound electrode body 10Y according to Embodiment 3 differs from the wound electrode body 10 according to Embodiment 1 in that the boundaries between the pair of flat portions 91 and the pair of curved portions 92 are in different positions. The other configurations are substantially the same.

[0075] When the width direction is defined as the direction in which the pair of flat sections 91 face each other and the direction perpendicular to the winding axis Z of the wound electrode body 10, in a cross section perpendicular to the winding axis Z of the wound electrode body 10Y, the boundaries between the pair of flat sections 91 and the pair of curved sections 92 are inclined outward in the width direction as they move from the outer circumference to the inner circumference of the wound electrode body 10. The width direction is parallel to the second direction D2.

[0076] In a cross-section perpendicular to the winding axis Z of the wound electrode body 10Y, the first boundary P1 and the second boundary P2 are alternately arranged at the boundaries between the pair of flat portions 91 and the pair of curved portions 92, such that they move outward in the width direction as you move from the outer circumference to the inner circumference of the wound electrode body 10.

[0077] Even when configured as described above, the wound electrode body 10Y according to Embodiment 3 can obtain substantially the same effects as that of Embodiment 1. In addition, by having the boundary positions of the pair of flat portions 91 and the pair of curved portions 92 as described above, the proportion (length) of metal foil arranged inside the wound electrode body 10 in the pair of flat portions 91 can be made larger than the proportion (length) of metal foil arranged outside the wound electrode body 10.

[0078] Generally, heat tends to accumulate inside a wound electrode body. However, by using the above configuration, the proportion of metal foil inside the wound electrode body 10Y can be increased, thereby improving heat dissipation inside the wound electrode body 10Y.

[0079] (Other variations) In embodiments 1 to 3 described above, the first resin member 112 is thinner than the first metal foil 111 and the second resin member 122 is thinner than the second metal foil 121, but the invention is not limited to these cases. The thicknesses of the first resin member 112 and the first metal foil 111 may be the same, or the first resin member 112 may be thicker than the first metal foil 111. Similarly, the thicknesses of the second resin member 122 and the second metal foil 121 may be the same, or the second resin member 122 may be thicker than the second metal foil 121.

[0080] The embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, and all modifications are within the meaning and scope equivalent to the claims. [Explanation of Symbols]

[0081] 1 Battery, 10,10X,10Y wound electrode body, 11 Positive electrode, 12 Negative electrode, 13 Separator, 15 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 member, 71 insulating bracket, 72 circumferential insulating part, 73 bottom insulating part, 80 fuse protection part, 91 flat part, 92 curved part, 110 first base material, 111 first metal foil, 112 first resin member, 113 positive electrode active material layer, 120 second base material, 121 second metal foil, 122 second resin member, 123 negative electrode active material layer, 150A first tab, 150B second tab, B1, B2 boundary, D1 first direction, D2 second direction, D3 third direction, DT thickness direction, P1 first boundary, P2 second boundary, Z winding axis.

Claims

1. A wound electrode body having a positive electrode and a negative electrode wound in a flat shape via a separator, a pair of flat portions facing each other with respect to the winding center, and a pair of curved portions connecting the ends of the pair of flat portions, The positive electrode includes a first substrate in which a first metal foil and a first resin member are alternately bonded along the winding direction of the wound electrode body. The negative electrode includes a second base material in which a second metal foil and a second resin member are alternately bonded along the winding direction. In each of the pair of flat portions, the first metal foil and the second metal foil are arranged alternately in the direction in which the pair of flat portions face each other. A wound electrode body in which, in each of the pair of curved portions, the first resin member and the second resin member are arranged alternately in the radial direction of the wound electrode body.

2. In a cross-section perpendicular to the winding axis of the wound electrode body, The first boundary, which is the boundary between the first metal foil and the first resin member, is located at the boundary between the pair of flat portions and the pair of curved portions. The wound electrode body according to claim 1, wherein the second boundary, which is the boundary between the second metal foil and the second resin member, is located at the boundary between the pair of flat portions and the pair of curved portions.

3. In the cross-section perpendicular to the winding axis, The wound electrode body according to claim 2, wherein at each boundary between the pair of flat portions and the pair of curved portions, the first boundary and the second boundary are arranged alternately in the direction in which the first metal foil and the second metal foil are arranged alternately.

4. When the direction perpendicular to the direction in which the winding shaft and the pair of flat portions face each other is defined as the width direction, In the cross-section perpendicular to the winding axis, The wound electrode body according to claim 2, wherein at each boundary between the pair of flat portions and the pair of curved portions, the first boundary and the second boundary are alternately arranged such that they move inward in the width direction as you move from the outer circumference to the inner circumference of the wound electrode body.

5. When the direction perpendicular to the direction in which the winding shaft and the pair of flat portions face each other is defined as the width direction, In the cross-section perpendicular to the winding axis, The wound electrode body according to claim 2, wherein at each boundary between the pair of flat portions and the pair of curved portions, the first boundary and the second boundary are alternately arranged such that they move outward in the width direction as you move from the outer circumference to the inner circumference of the wound electrode body.

6. The wound electrode body according to any one of claims 1 to 5, wherein the thickness of the first resin member is thinner than that of the first metal foil.

7. The wound electrode body according to claim 6, wherein the thickness of the second resin member is thinner than that of the second metal foil.

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