Battery manufacturing method

Abstract

To provide a manufacturing method for a battery, by which a battery with higher reliability can be achieved.SOLUTION: A manufacturing method for a battery disclosed herein is a manufacturing method for a battery including a wound electrode body in which a first separator 71 with a band shape, a positive electrode sheet 22, a second separator 72, and a negative electrode sheet 24 are wound, in which the positive electrode sheet 22 and the first separator 71 are attached together by a first adhesive layer 81 and the positive electrode sheet 22 and the second separator 72 are attached together by a second adhesive layer 82. This manufacturing method includes an adhesive layer forming step of forming the first adhesive layer 81 on at least one surface of the positive electrode sheet 22 and the first separator 71 and forming the second adhesive layer 82 on at least one surface of the positive electrode sheet 22 and the second separator 72, and a wound electrode body manufacturing step of manufacturing a wound electrode body 20 by winding the first separator 71 with a band shape, the positive electrode sheet 22 with a band shape, the second separator 72 with a band shape, and the negative electrode sheet 24 with a band shape.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a battery. [Background technology]

[0002] Conventionally, batteries have been known that include a wound electrode assembly in which a strip-shaped positive electrode sheet having a positive electrode active material layer and a strip-shaped negative electrode sheet having a negative electrode active material layer are wound in the longitudinal direction with a strip-shaped separator interposed therebetween.For example, Patent Document 1 discloses a battery manufacturing method that includes the steps of preparing a separator having an adhesive layer formed on its surface, placing the separator between a positive electrode sheet and a negative electrode sheet, and winding the stack to form an electrode assembly, and hot-pressing the electrode assembly to integrate at least one of the positive electrode sheet and the negative electrode sheet with the separator. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5328034 Summary of the Invention [Problem to be solved by the invention]

[0004] By arranging an adhesive layer at a desired position on the electrode assembly, for example, the formability of the electrode assembly can be suitably improved, thereby improving the reliability of the battery. However, for example, if a separator with an adhesive layer is wound around a reel or the like and then unwrapped to produce a wound electrode assembly, the adhesive layer may be damaged or deformed. In addition, in recent years, the required battery capacity and the size and number of stacking of the electrode assembly tend to be appropriately changed accordingly. Therefore, the position where the adhesive layer should be arranged varies depending on the size of each electrode assembly. However, if separators and positive electrode sheets with adhesive layer positions changed to match each electrode assembly are prepared, costs may increase. The present invention has been made in consideration of these issues and aims to provide a battery manufacturing method that realizes batteries with higher reliability. [Means for solving the problem]

[0005] The battery manufacturing method disclosed herein includes a wound electrode body formed by winding a first strip-shaped separator, a strip-shaped positive electrode sheet, a second strip-shaped separator, and a strip-shaped negative electrode sheet, the positive electrode sheet and the first separator being bonded together by a first adhesive layer, and the positive electrode sheet and the second separator being bonded together by a second adhesive layer. The manufacturing method includes an adhesive layer forming step of forming the first adhesive layer on at least one surface of the positive electrode sheet and the first separator and forming the second adhesive layer on at least one surface of the positive electrode sheet and the second separator, and a wound electrode body fabricating step of fabricating the wound electrode body by winding the first strip-shaped separator, the positive electrode sheet, the second strip-shaped separator, and the negative electrode sheet.

[0006] According to this configuration, the wound electrode assembly fabrication process is carried out continuously after the adhesive layer formation process. This makes it easier to control the position where the adhesive layer is formed, allowing the adhesive layer to be suitably positioned in the desired position of the electrode assembly. Furthermore, since the adhesive layer is not wound on a reel or the like after it is formed, the adhesive layer is not damaged, and an electrode assembly with a higher quality adhesive layer can be fabricated. Therefore, according to this manufacturing method, for example, it is possible to improve the formability of the electrode assembly and provide a more reliable battery. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view schematically showing a battery according to one embodiment. [Figure 2] FIG. 2 is a schematic vertical cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is a schematic vertical cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a schematic cross-sectional view taken along line IV-IV in FIG. [Figure 5] FIG. 5 is a perspective view that schematically shows the electrode body attached to the sealing plate. [Figure 6] FIG. 6 is a perspective view that schematically shows an electrode assembly to which a positive electrode second current collecting portion and a negative electrode second current collecting portion are attached. [Figure 7] FIG. 7 is a schematic diagram showing the configuration of a wound electrode body. [Figure 8] FIG. 8 is an enlarged view that schematically shows the interfaces between the positive electrode sheet, the negative electrode sheet, the first separator, and the second separator of the wound electrode body. [Figure 9] FIG. 9 is a diagram schematically illustrating a manufacturing method according to an embodiment. [Figure 10] FIG. 10 is a diagram showing a schematic configuration of a winding machine. [Figure 11] FIG. 11 is a cross-sectional view that schematically shows the winding core disposed at the first position. [Figure 12] FIG. 12 is a diagram showing a schematic configuration of a winding machine. [Figure 13] FIG. 13 is a view of the battery according to the second embodiment, corresponding to FIG. [Figure 14] FIG. 14 is a diagram schematically illustrating another example of the configuration of the winding machine. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the technology disclosed herein will be described with reference to the drawings. It should be noted that matters other than those specifically mentioned in this specification that are necessary for implementing the technology disclosed herein (e.g., the general configuration and manufacturing process of a battery that do not characterize the technology disclosed herein) can be understood as design matters for a person skilled in the art based on prior art in the relevant field. The technology disclosed herein can be implemented based on the content disclosed in this specification and common technical knowledge in the relevant field. In this specification, the expression "A to B" indicating a range means "A or more and B or less," as well as "greater than A" and "less than B."

[0009] In this specification, the term "battery" refers to any power storage device capable of extracting electrical energy, and is a concept that encompasses primary batteries and secondary batteries. Furthermore, in this specification, the term "secondary battery" refers to any power storage device that can be repeatedly charged and discharged by the movement of charge carriers between a positive electrode and a negative electrode via an electrolyte, and is a concept that encompasses so-called storage batteries (chemical batteries) such as lithium-ion secondary batteries and nickel-metal hydride batteries, and capacitors (physical batteries) such as electric double-layer capacitors.

[0010] The battery manufacturing method disclosed herein is a method for manufacturing a battery including a wound electrode assembly in which a strip-shaped first separator, a strip-shaped positive electrode sheet, a strip-shaped second separator, and a strip-shaped negative electrode sheet are wound together, the positive electrode sheet and the first separator being bonded together by a first adhesive layer, and the positive electrode sheet and the second separator being bonded together by a second adhesive layer. This manufacturing method includes at least an adhesive layer forming step of forming the first adhesive layer and the second adhesive layer, and a wound electrode assembly fabricating step of fabricating the wound electrode assembly. Here, we will first describe the configuration of a battery manufactured by this manufacturing method, and then describe the manufacturing method disclosed herein.

[0011] <Battery configuration> An embodiment of a battery manufactured by the manufacturing method disclosed herein will be described below with reference to FIGS. 1 to 7. FIG. 1 is a perspective view of a battery 100. FIG. 2 is a schematic longitudinal cross-sectional view taken along line II-II in FIG. 1. FIG. 3 is a schematic longitudinal cross-sectional view taken along line III-III in FIG. 1. FIG. 4 is a schematic transverse cross-sectional view taken along line IV-IV in FIG. 1. FIG. 5 is a schematic perspective view of an electrode assembly attached to a sealing plate. FIG. 6 is a perspective view of an electrode assembly to which a positive electrode second current collector and a negative electrode second current collector are attached. FIG. 7 is a diagram showing the configuration of a wound electrode assembly. In the following description, the symbols L, R, F, Rr, U, and D in the drawings represent left, right, front, rear, top, and bottom. In addition, the symbol X in the drawings indicates the "short side direction of the battery," the symbol Y indicates the "long side direction of the battery," and the symbol Z indicates the "vertical direction of the battery." However, these directions are merely for the convenience of explanation and do not limit the installation form of the battery 100 in any way.

[0012] 1 and 2, the battery 100 includes a wound electrode body 20 and a battery case 10 that houses the wound electrode body 20. Although not shown, the battery 100 further includes an electrolyte. The battery 100 is preferably a non-aqueous electrolyte secondary battery, such as a lithium ion secondary battery.

[0013] The battery case 10 is a housing that houses the wound electrode body 20. Here, as shown in FIG. 1, the battery case 10 has a rectangular parallelepiped (square) outer shape with a bottom. The material of the battery case 10 may be the same as that conventionally used, and is not particularly limited. The battery case 10 is preferably made of metal. Examples of materials for the battery case 10 include aluminum, aluminum alloy, iron, and iron alloy.

[0014] As shown in FIGS. 1 and 2, the battery case 10 includes an exterior body 12 and a sealing plate 14. The exterior body 12 is a flat, bottomed, rectangular container having an opening 12h on its top surface. The exterior body 12 includes a bottom wall 12a that is substantially rectangular in plan view, a pair of long side walls 12b that extend from the bottom wall 12a and face each other, and a pair of short side walls 12c that extend from the bottom wall 12a and face each other. The area of ​​the short side walls 12c is smaller than the area of ​​the long side walls 12b. The sealing plate 14 is a member that closes the opening 12h of the exterior body 12 and is a plate-like member that is substantially rectangular in plan view. The battery case 10 is integrated by joining (e.g., welding) the sealing plate 14 to the periphery of the opening 12h of the exterior body 12. The battery case 10 is hermetically sealed (sealed).

[0015] As shown in Fig. 2, sealing plate 14 is provided with injection hole 15, gas release valve 17, and two terminal extraction holes 18 and 19. Injection hole 15 is a through-hole for injecting the electrolyte into battery case 10 after sealing plate 14 is assembled to exterior body 12. Injection hole 15 is sealed with sealing member 16 after the electrolyte is injected. Gas release valve 17 is a thin-walled portion configured to break when the pressure inside battery case 10 reaches or exceeds a predetermined value, thereby releasing gas inside battery case 10 to the outside.

[0016] The battery case 10 can accommodate an electrolyte together with the wound electrode assembly 20 as described above. Any electrolyte used in conventionally known batteries can be used without any particular limitation. As an example, a non-aqueous electrolyte solution in which a supporting salt is dissolved in a non-aqueous solvent can be used. Examples of non-aqueous solvents include carbonate-based solvents such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. Examples of supporting salts include fluorine-containing lithium salts such as LiPF6. The non-aqueous electrolyte solution may contain various additives as needed. The electrolyte may be solid (solid electrolyte) and integrated with the electrode assembly.

[0017] A positive electrode terminal 30 is attached to one end of the sealing plate 14 in the long side direction Y (the left side in FIGS. 1 and 2). A negative electrode terminal 40 is attached to the other end of the sealing plate 14 in the long side direction Y (the right side in FIGS. 1 and 2). The positive electrode terminal 30 and the negative electrode terminal 40 are inserted through the terminal lead-out holes 18 and 19 and are exposed on the outer surface of the sealing plate 14. The positive electrode terminal 30 is electrically connected to a plate-shaped positive electrode external conductive member 32 on the outside of the battery case 10. The negative electrode terminal 40 is electrically connected to a plate-shaped negative electrode external conductive member 42 on the outside of the battery case 10. The positive electrode external conductive member 32 and the negative electrode external conductive member 42 are connected to other secondary batteries or external devices via external connection members such as bus bars. The positive electrode external conductive member 32 and the negative electrode external conductive member 42 are preferably made of a metal with excellent conductivity, such as aluminum, an aluminum alloy, copper, or a copper alloy. However, the positive electrode external conductive member 32 and the negative electrode external conductive member 42 are not essential and may be omitted in other embodiments.

[0018] As shown in Figures 3 to 5, the battery 100 here has a plurality of (three) wound electrode bodies 20 housed in a battery case 10. The detailed structure of the wound electrode bodies 20 will be described later, but each wound electrode body 20 is provided with a positive electrode tab group 25 and a negative electrode tab group 27 (see Figure 4). As shown in Figure 4, these electrode tab groups (positive electrode tab group 25 and negative electrode tab group 27) are bent with their electrode current collectors (positive electrode current collector 50 and negative electrode current collector 60) joined together.

[0019] The positive electrode tab groups 25 of each of the multiple wound electrode bodies 20 are connected to a positive electrode terminal 30 via a positive electrode current collector 50. The positive electrode current collector 50 is housed inside the battery case 10. As shown in FIGS. 2 and 5, the positive electrode current collector 50 includes a positive electrode first current collector 51 and a positive electrode second current collector 52. The positive electrode first current collector 51 is a plate-shaped conductive member extending in the long side direction Y along the inner surface of the sealing plate 14. The positive electrode second current collector 52 is a plate-shaped conductive member extending in the up-down direction Z of the battery 100. The lower end 30c of the positive electrode terminal 30 is inserted into the battery case 10 through the terminal lead-out hole 18 of the sealing plate 14 and is connected to the positive electrode first current collector 51 (see FIG. 2). 4 to 6, the battery 100 includes positive electrode second current collecting members 52 in a number corresponding to the number of the plurality of wound electrode bodies 20. Each positive electrode second current collecting member 52 is connected to a positive electrode tab group 25 of the wound electrode body 20. As shown in FIG. 4, the positive electrode tab group 25 of the wound electrode body 20 is bent so that the positive electrode second current collecting member 52 faces one side surface 20e of the wound electrode body 20. This electrically connects the upper end of the positive electrode second current collecting member 52 to the positive electrode first current collecting member 51. The positive electrode terminal 30 and the positive electrode current collecting part 50 are preferably made of a metal with excellent conductivity. The positive electrode terminal 30 and the positive electrode current collecting part 50 may be made of, for example, aluminum or an aluminum alloy.

[0020] Meanwhile, the negative electrode tab groups 27 of each of the multiple wound electrode bodies 20 are connected to the negative electrode terminal 40 via a negative electrode current collector 60. The connection structure on the negative electrode side is substantially the same as the connection structure on the positive electrode side described above. Specifically, as shown in FIGS. 2 and 5, the negative electrode current collector 60 includes a negative electrode first current collector 61 and a negative electrode second current collector 62. The negative electrode first current collector 61 is a plate-shaped conductive member extending in the long side direction Y along the inner surface of the sealing plate 14. The negative electrode second current collector 62 is a plate-shaped conductive member extending in the up-down direction Z of the battery 100. The lower end 40c of the negative electrode terminal 40 is inserted into the battery case 10 through the terminal pull-out hole 19 and connected to the negative electrode first current collector 61 (see FIG. 2). As shown in FIGS. 4 to 6, the battery 100 includes negative electrode second current collecting members 62, the number of which corresponds to the number of the wound electrode bodies 20. Each negative electrode second current collecting member 62 is connected to a negative electrode tab group 27 of the wound electrode body 20. As shown in FIGS. 4 and 5, the negative electrode tab group 27 of the wound electrode body 20 is bent so that the negative electrode second current collecting member 62 faces the other side surface 20h of the wound electrode body 20. This electrically connects the upper end of the negative electrode second current collecting member 62 to the negative electrode first current collecting member 61. The negative electrode terminal 40 and the negative electrode current collecting part 60 are preferably made of a metal with excellent conductivity. The negative electrode terminal 40 and the negative electrode current collecting part 60 may be made of, for example, copper or a copper alloy.

[0021] In the battery 100, various insulating members are attached to prevent electrical conduction between the wound electrode body 20 and the battery case 10. For example, as shown in FIGS. 1 and 2, the positive electrode external conductive member 32 and the negative electrode external conductive member 42 are insulated from the sealing plate 14 by an external insulating member 92. Also, as shown in FIG. 2, a gasket 90 is attached to each of the terminal lead-out holes 18, 19 of the sealing plate 14. This prevents electrical conduction between the positive electrode terminal 30 (or the negative electrode terminal 40) inserted into the terminal lead-out holes 18, 19 and the sealing plate 14. An internal insulating member 94 is disposed between the positive electrode current collector 50 and the negative electrode current collector 60 and the inner surface of the sealing plate 14. This prevents electrical conduction between the positive electrode current collector 50 and the negative electrode current collector 60 and the sealing plate 14. The internal insulating member 94 may have a protrusion that protrudes toward the wound electrode body 20. Furthermore, the plurality of wound electrode bodies 20 are placed inside the exterior body 12 while covered with an electrode body holder 29 made of an insulating resin sheet. This prevents direct contact between the wound electrode body 20 and the exterior body 12. The material of each of the insulating members described above is not particularly limited as long as it has a predetermined insulating property. Examples of such materials include synthetic resin materials such as polyolefin resins such as polypropylene (PP) and polyethylene (PE), and fluorine-based resins such as perfluoroalkoxyalkane and polytetrafluoroethylene (PTFE).

[0022] As shown in FIG. 3, three wound electrode bodies 20 are housed in the exterior housing 12. However, the number of wound electrode bodies arranged inside one exterior housing 12 is not particularly limited and may be four or more, or may be one. The wound electrode body 20 is a wound electrode body in which a strip-shaped first separator 71, a strip-shaped positive electrode sheet 22, a strip-shaped second separator 72, and a strip-shaped negative electrode sheet 24 are wound together. Here, the positive electrode sheet 22 and the first separator 71 are bonded by a first adhesive layer 81 (see FIG. 8). Furthermore, the positive electrode sheet 22 and the second separator 72 are bonded by a second adhesive layer 82 (see FIG. 8). The wound electrode body 20 is preferably flat. As shown in FIG. 3, the wound electrode body 20 has, for example, a flat shape and has a pair of curved portions 20r that face the bottom wall 12a and the sealing plate 14 of the outer casing 12, and a flat portion 20f that connects the pair of curved portions 20r and faces the long side wall 12b of the outer casing 12. In this specification, a flat wound electrode body refers to a wound electrode body that is approximately oval in cross section, or a so-called racetrack shape (see FIG. 3).

[0023] As shown in Fig. 7, the wound electrode body 20 is configured by stacking a strip-shaped positive electrode sheet 22 and a strip-shaped negative electrode sheet 24 insulated from each other via strip-shaped first separator 71 and second separator 72, and winding them longitudinally around a winding axis WL. The wound electrode body 20 is disposed inside the exterior housing 12 with the winding axis WL (see Fig. 7) oriented parallel to the long side direction Y of the exterior housing 12. In other words, the wound electrode body 20 is disposed inside the exterior housing 12 with the winding axis WL oriented parallel to the bottom wall 12a and perpendicular to the short side wall 12c. An end face of the wound electrode body 20 (in other words, the stacking surface where the positive electrode sheet 22 and the negative electrode sheet 24 are stacked) faces the short side wall 12c.

[0024] As shown in FIG. 7, the positive electrode sheet 22 is a strip-shaped member. The positive electrode sheet 22 includes a strip-shaped positive electrode collector 22c, and a positive electrode active material layer 22a and a positive electrode protective layer 22p, which are fixed to at least one surface of the positive electrode collector 22c. However, the positive electrode protective layer 22p is not essential and may be omitted in other embodiments. For each component of the positive electrode sheet 22, any conventionally known material that can be used in a general battery (e.g., a lithium-ion secondary battery) can be used without any particular restrictions. For example, the positive electrode collector 22c is preferably made of a conductive metal such as aluminum, an aluminum alloy, nickel, or stainless steel. Here, the positive electrode collector 22c is a metal foil, specifically, an aluminum foil.

[0025] As shown in FIG. 7, the positive electrode sheet 22 has a plurality of positive electrode tabs 22t provided at one end (the left end in FIG. 7) in the long side direction Y of the wound electrode body 20. The plurality of positive electrode tabs 22t are provided at predetermined intervals (intermittently) along the longitudinal direction. The positive electrode tabs 22t are connected to the positive electrode sheet 22. Here, the positive electrode tab 22t is a part of the positive electrode current collector 22c and is made of metal foil (specifically, aluminum foil). The positive electrode tab 22t is a region where the positive electrode active material layer 22a is not formed and the positive electrode current collector 22c is exposed. However, the positive electrode tab 22t may be partially provided with the positive electrode active material layer 22a and / or the positive electrode protective layer 22p, or may be a member separate from the positive electrode current collector 22c. Here, each of the plurality of positive electrode tabs 22t is trapezoidal. However, the shape of the positive electrode tabs 22t is not limited thereto. Furthermore, the size of the plurality of positive electrode tabs 22t is not particularly limited. The shape and size of the positive electrode tab 22t can be appropriately adjusted by its formation position, for example, taking into consideration the state of connection to the positive electrode current collecting part 50. As shown in FIG. 4, the multiple positive electrode tabs 22t are stacked at one end of the positive electrode sheet 22 in the long side direction Y (the left end in FIG. 4) to form a positive electrode tab group 25.

[0026] As shown in FIG. 7, the positive electrode active material layer 22a is provided in a strip shape along the longitudinal direction of the strip-shaped positive electrode current collector 22c. The positive electrode active material layer 22a contains a positive electrode active material (e.g., a lithium transition metal composite oxide such as lithium nickel cobalt manganese composite oxide) that can reversibly store and release charge carriers. The positive electrode active material layer 22a preferably contains a lithium transition metal composite oxide as the positive electrode active material, and more preferably, the lithium transition metal composite oxide has a high nickel (Ni) content. For example, in the lithium transition metal composite oxide, the nickel content relative to the total of metal elements other than lithium is preferably 55 mol % or more, more preferably 70 mol % or more, and even more preferably 75 mol % or more. This allows the battery 100 to have a higher capacity.

[0027] When the total solid content of the positive electrode active material layer 22a is taken as 100% by mass, the positive electrode active material may account for approximately 80% by mass or more, typically 90% by mass or more, for example 95% by mass or more. The positive electrode active material layer 22a may contain optional components other than the positive electrode active material, such as a conductive material, a binder, various additive components, etc. An example of the conductive material is a carbon material such as acetylene black (AB). An example of the binder is a fluorine-based resin such as polyvinylidene fluoride (PVdF).

[0028] Although not particularly limited, when the weight per unit area of ​​the positive electrode active material layer 22a is a (g) and the amount of moisture generated when the positive electrode active material layer 22a is heated from 150°C to 300°C is b (g), it is preferable that the ratio (b / a) of the moisture amount b to the weight a be less than 0.2%.

[0029] The positive electrode protective layer 22p is a layer configured to have lower electrical conductivity than the positive electrode active material layer 22a. As shown in FIG. 7, the positive electrode protective layer 22p is provided at the boundary between the positive electrode collector 22c and the positive electrode active material layer 22a in the long side direction Y. Here, the positive electrode protective layer 22p is provided at one end of the positive electrode collector 22c in the long side direction Y (the left end in FIG. 7). However, the positive electrode protective layer 22p may be provided at both end portions in the long side direction Y. The provision of the positive electrode protective layer 22p can prevent the positive electrode collector 22c and the negative electrode active material layer 24a from coming into direct contact with each other when the first separator 71 and the second separator 72 are damaged, thereby preventing an internal short circuit in the battery 100.

[0030] The positive electrode protective layer 22p contains an insulating inorganic filler, for example, ceramic particles such as alumina. When the total solid content of the positive electrode protective layer 22p is taken as 100 mass%, the inorganic filler may account for approximately 50 mass% or more, typically 70 mass% or more, for example 80 mass% or more. The positive electrode protective layer 22p may contain optional components other than the inorganic filler, such as a conductive material, a binder, various additive components, etc. The conductive material and binder may be the same as those exemplified as those that may be contained in the positive electrode active material layer 22a.

[0031] As shown in FIG. 7, the negative electrode sheet 24 is a strip-shaped member. The negative electrode sheet 24 has a strip-shaped negative electrode current collector 24c and a negative electrode active material layer 24a fixed to at least one surface of the negative electrode current collector 24c. For each component of the negative electrode sheet 24, any conventionally known material that can be used in a general battery (e.g., a lithium-ion secondary battery) can be used without particular limitation. For example, the negative electrode current collector 24c is preferably made of a conductive metal such as copper, a copper alloy, nickel, or stainless steel. Here, the negative electrode current collector 24c is a metal foil, specifically, a copper foil.

[0032] As shown in FIG. 7, the negative electrode sheet 24 has multiple negative electrode tabs 24t provided at one end (the right end in FIG. 7) in the long side direction Y of the wound electrode body 20. The multiple negative electrode tabs 24t are provided at predetermined intervals (intermittently) along the longitudinal direction. The negative electrode tabs 24t are connected to the negative electrode sheet 24. Here, the negative electrode tab 24t is part of the negative electrode current collector 24c and is made of metal foil (specifically, copper foil). Here, the negative electrode tab 24t is a region where the negative electrode active material layer 24a is not formed and the negative electrode current collector 24c is exposed. However, the negative electrode tab 24t may partially have the negative electrode active material layer 24a formed thereon or may be a member separate from the negative electrode current collector 24c. Here, each of the multiple negative electrode tabs 24t is trapezoidal. However, the shape and size of the multiple negative electrode tabs 24t can be adjusted as appropriate, similar to the positive electrode tab 22t. As shown in FIG. 4, the negative electrode tabs 24t are stacked at one end in the long side direction Y of the negative electrode sheet 24 (the right end in FIG. 4) to form a negative electrode tab group 27.

[0033] As shown in FIG. 7, the negative electrode active material layer 24a is provided in a strip-like shape along the longitudinal direction of the strip-shaped negative electrode current collector 24c. The negative electrode active material layer 24a contains a negative electrode active material (e.g., a carbon material such as graphite) capable of reversibly absorbing and releasing charge carriers. The width (length in the long side direction Y; the same applies hereinafter) of the negative electrode active material layer 24a is preferably greater than the width of the positive electrode active material layer 22a. When the total solid content of the negative electrode active material layer 24a is taken as 100% by mass, the negative electrode active material may account for approximately 80% by mass or more, typically 90% by mass or more, for example, 95% by mass or more. The negative electrode active material layer 24a may contain optional components other than the negative electrode active material, such as a conductive material, a binder, a dispersant, and various additives. Examples of binders include rubbers such as styrene butadiene rubber (SBR). Examples of dispersants include celluloses such as carboxymethyl cellulose (CMC).

[0034] The first separator 71 and the second separator 72 are strip-shaped members. The first separator 71 and the second separator 72 are insulating sheets formed with a plurality of fine through-holes through which charge carriers can pass. The widths of the first separator 71 and the second separator 72 are greater than the width of the negative electrode active material layer 24a. By interposing the first separator 71 and the second separator 72 between the positive electrode sheet 22 and the negative electrode sheet 24, contact between the positive electrode sheet 22 and the negative electrode sheet 24 is prevented and charge carriers (e.g., lithium ions) can be transferred between the positive electrode sheet 22 and the negative electrode sheet 24.

[0035] FIG. 8 is an enlarged view schematically illustrating the interfaces between the positive electrode sheet 22, the negative electrode sheet 24, the first separator 71, and the second separator 72 of the wound electrode body 20. As described above, in the battery 100 disclosed herein, the positive electrode sheet 22 and the first separator 71 are bonded together by a first adhesive layer 81, and the positive electrode sheet 22 and the second separator 72 are bonded together by a second adhesive layer 82. The first adhesive layer 81 may be provided on the surface of the first separator 71 that faces the positive electrode sheet 22. Alternatively, the first adhesive layer 81 may be provided on the surface of the positive electrode sheet 22 that faces the first separator 71. Furthermore, the second adhesive layer 82 may be provided on the surface of the second separator 72 that faces the positive electrode sheet 22. Alternatively, the second adhesive layer 82 may be provided on the surface of the positive electrode sheet 22 that faces the second separator 72. The "surface of the positive electrode sheet" may be the surface of the positive electrode active material layer or the surface of the positive electrode current collector. When the first adhesive layer and / or the second adhesive layer is provided on the surface of the positive electrode sheet, preferably, the positive electrode sheet has a positive electrode active material layer on both sides of the positive electrode current collector, and the first adhesive layer and / or the second adhesive layer is provided on the surface of the positive electrode active material layer.

[0036] The positions of the first adhesive layer 81 and the second adhesive layer 82 are not particularly limited as long as the first adhesive layer 81 and the second adhesive layer 82 can adhere the positive electrode sheet 22, the first separator 71, and the second separator 72 to each other. For example, the first adhesive layer 81 may be provided on the surface of the positive electrode sheet 22 that faces the first separator 71, and the second adhesive layer 82 may be provided on the surface of the positive electrode sheet 22 that faces the second separator 72. Preferably, the first adhesive layer 81 is provided on the surface of the first separator 71 that faces the positive electrode sheet 22, and the second adhesive layer 82 is provided on the surface of the positive electrode sheet 22 that faces the second separator 72. More preferably, the first adhesive layer 81 is provided on the surface of the first separator 71 that faces the positive electrode sheet 22, and the second adhesive layer 82 is provided on the surface of the second separator 72 that faces the positive electrode sheet 22. This allows the first adhesive layer 81 and the second adhesive layer 82 to more effectively exert their adhesion.

[0037] In a configuration in which the first adhesive layer 81 is provided on the surface of the first separator 71, the first adhesive layer 81 may be disposed on the outermost surface of the first separator 71. In a configuration in which the second adhesive layer 82 is provided on the surface of the second separator 72, the second adhesive layer 82 may be disposed on the outermost surface of the second separator 72. Although not particularly limited, the first separator 71 preferably has, for example, a base material layer 85, a heat-resistant layer 87 provided on the base material layer 85, and a first adhesive layer 81 provided on the heat-resistant layer 87. In addition, the second separator 72 preferably has, for example, a base material layer 85, a heat-resistant layer 87 provided on the base material layer 85, and a second adhesive layer 82 provided on the heat-resistant layer 87. However, the first adhesive layer 81 and the second adhesive layer 82 may each be provided directly on the surface of the base material layer 85. Alternatively, the first adhesive layer 81 and the second adhesive layer 82 may be provided on the base material layer 85 via any other layer.

[0038] As the substrate layer 85, any microporous film used in a separator of a conventionally known battery can be used without particular limitation. The substrate layer 85 is preferably, for example, a porous sheet-like member. The substrate layer 85 may have a single-layer structure or a two- or more-layer structure, for example, a three-layer structure. The substrate layer 85 is preferably made of a polyolefin resin. This ensures sufficient flexibility of the separator and facilitates the production of the wound electrode body 20 (winding and press molding). Polyolefin resins are preferably polyethylene (PE), polypropylene (PP), or a mixture thereof, and more preferably made of PE. Furthermore, although not particularly limited, the thickness of the substrate layer 85 is preferably 3 μm to 25 μm, more preferably 3 μm to 18 μm, and even more preferably 5 μm to 14 μm.

[0039] Here, the heat-resistant layer 87 is provided on the base material layer 85. The heat-resistant layer 87 may be provided directly on the surface of the base material layer 85, or may be provided on the base material layer 85 via another layer. However, the heat-resistant layer 87 is not essential and may be omitted in other embodiments. The basis weight of the heat-resistant layer 87 here is uniform in the longitudinal and width directions of the separator. Although not particularly limited, the thickness of the heat-resistant layer 87 is preferably 0.3 μm or more and 6 μm or less, more preferably 0.5 μm or more and 6 μm or less, and even more preferably 1 μm or more and 4 μm or less.

[0040] The heat-resistant layer 87 preferably contains an inorganic filler and a heat-resistant layer binder. Any inorganic filler conventionally known for this type of application can be used without any particular limitation. The inorganic filler preferably contains insulating ceramic particles. Among these, inorganic oxides such as alumina, zirconia, silica, and titania, metal hydroxides such as aluminum hydroxide, and clay minerals such as boehmite are preferred in consideration of heat resistance and availability, with alumina and boehmite being more preferred. Furthermore, from the viewpoint of suppressing thermal shrinkage of the separator, compounds containing aluminum are particularly preferred. The proportion of the inorganic filler relative to the total mass of the heat-resistant layer 87 is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0041] As the binder for the heat-resistant layer, any binder that has been conventionally used for this type of application can be used without any particular limitation. Specific examples include acrylic resins, fluorine-based resins, epoxy resins, urethane resins, and ethylene vinyl acetate resins. Among these, acrylic resins are preferred.

[0042] The first adhesive layer 81 and the second adhesive layer 82 are bonded to the electrodes (positive electrode sheet 22 and / or negative electrode sheet 24) by, for example, heating or pressing (typically, press molding), etc. The first adhesive layer 81 and the second adhesive layer 82 may have the same configuration or different configurations.

[0043] The first adhesive layer 81 and the second adhesive layer 82 contain an adhesive layer binder. Any conventionally known resin material having a certain viscosity relative to the electrode can be used as the adhesive layer binder, without any particular restrictions. Specific examples include acrylic resins, fluorine-based resins, epoxy resins, urethane resins, and ethylene vinyl acetate resins. Fluorine-based resins and acrylic resins are preferred because they have high flexibility and can more effectively exhibit adhesiveness to the electrode. Examples of fluorine-based resins include polyvinylidene fluoride (PVdF) and polytetrafluoroethylene (PTFE). The type of adhesive layer binder may be the same as or different from the heat-resistant layer binder. The proportion of the adhesive layer binder relative to the total mass of the adhesive layer is preferably 25% by mass or more, may be 50% by mass or more, and more preferably 80% by mass or more. This allows the desired adhesiveness to the electrode to be accurately exhibited.

[0044] The first adhesive layer 81 and the second adhesive layer 82 may contain other materials (such as the inorganic filler listed as a component of the heat-resistant layer 73) in addition to the adhesive layer binder. When the adhesive layer contains an inorganic filler, the proportion of the inorganic filler relative to the total mass of the adhesive layer is preferably 75 mass% or less, more preferably 50 mass% or less, and even more preferably 20 mass% or less. The thickness of the first adhesive layer 81 and the second adhesive layer 82 is preferably approximately 0.3 μm or more and 6 μm or less, more preferably 0.5 μm or more and 6 μm or less, and even more preferably 1 μm or more and 4 μm or less.

[0045] 8, the first separator 71 has a first surface 71a and a second surface 71b. Here, the first surface 71a of the first separator 71 faces one surface of the positive electrode sheet 22, and the second surface 71b faces one surface of the negative electrode sheet 24. In addition, the second separator 72 has a third surface 72a and a fourth surface 72b. Here, the third surface 72a of the second separator 72 faces the other surface of the positive electrode sheet 22, and the fourth surface 72b faces the other surface of the negative electrode sheet 24.

[0046] As shown in FIG. 8, the first surface 71a of the first separator 71 is provided with a first adhesive layer 81, and is preferably bonded to one surface of the positive electrode sheet 22. Although not particularly limited, the basis weight A (g / m 2 ) is 0.005 to 1.0 g / m 2 is preferable, and 0.02 to 0.04 g / m 2 However, the first adhesive layer 81 does not necessarily have to be provided over the entire area of ​​the first surface 71a. That is, the first surface 71a may have an area where no adhesive layer is formed.

[0047] 8, the third surface 72a of the second separator 72 is preferably provided with a second adhesive layer 82 and is bonded to the other surface of the positive electrode sheet 22. Although not particularly limited, the basis weight C (g / m 2 ) is 0.005 to 1.0 g / m 2 is preferable, and 0.02 to 0.04 g / m 2 However, the second adhesive layer 82 does not necessarily have to be provided over the entire area of ​​the third surface 72a. That is, the third surface 72a may have an area where no adhesive layer is formed.

[0048] The second surface 71b of the first separator 71 may or may not have an adhesive layer. When an adhesive layer is formed on the second surface 71b of the first separator 71, the basis weight B (g / m 2 ) is the basis weight A (g / m 2 ) is preferably smaller than 0.5 g / m. For example, the ratio (B / A) of the basis weight B of the adhesive layer on the second surface 71b to the basis weight A of the adhesive layer on the first surface 71a is preferably 0.5 or less, more preferably 0.25 or less, and particularly preferably 0.1 or less. Furthermore, although not particularly limited, when an adhesive layer is formed on the second surface 71b, the basis weight B is preferably 0.002 to 0.5 g / m. 2 is preferable, and 0.01 to 0.02 g / m 2 is more preferred.

[0049] The fourth surface 72b of the second separator 72 may or may not have an adhesive layer. When an adhesive layer is formed on the fourth surface 72b of the second separator 72, the basis weight D (g / m 2 ) is the basis weight C (g / m 2 ) is preferably smaller than the ratio (D / C) of the basis weight D of the adhesive layer on the fourth surface 72b to the basis weight C of the adhesive layer on the third surface 72a. For example, the ratio (D / C) of the basis weight D of the adhesive layer on the fourth surface 72b to the basis weight C of the adhesive layer on the third surface 72a is preferably 0.5 or less, more preferably 0.25 or less, and particularly preferably 0.1 or less. Furthermore, although not particularly limited, when an adhesive layer is formed on the fourth surface 72b, the basis weight D is preferably 0.002 to 0.5 g / m 2 is preferable, and 0.01 to 0.02 g / m 2 is more preferred.

[0050] The adhesive layer may be formed over the entire surface or may have a predetermined pattern, such as a dotted, striped, wavy, banded (stripe), or dashed pattern in plan view, or a combination thereof.

[0051] <Battery manufacturing method> The configuration of the battery 100 according to this embodiment has been described above. Next, a method for manufacturing the battery 100 will be described. Fig. 9 is a diagram schematically illustrating the manufacturing method disclosed herein. Figs. 10 and 12 are diagrams schematically illustrating a winding machine 200 that can be suitably used in the manufacturing method disclosed herein. Fig. 11 is a cross-sectional view schematically illustrating a winding core. First, the configuration of the winding machine 200 will be described with reference to Fig. 10.

[0052] As shown in FIG. 10 , the winding machine 200 is a device for winding a strip-shaped first separator 71, a strip-shaped positive electrode sheet 22, a strip-shaped second separator 72, and a strip-shaped negative electrode sheet 24. As shown in FIG. 10 , the winding machine 200 includes a turret 220, multiple winding cores (a first winding core 241, a second winding core 242, and a third winding core 243), a cutter 251, a presser jig 252, multiple rollers 261 to 266, a winding stop device 270, and a control device 300. The turret 220 is further provided with an index unit 280, and the index unit 280 is provided with multiple index rollers 281 to 283. Each component of the winding machine 200 has a required actuator, as appropriate. The control device 300 is configured to control each component of the winding machine 200 so that required operations are performed at predetermined timing according to a preset program. The control device 300 may be embodied by a computer such as a microcontroller, for example.

[0053] The positive electrode sheet 22, the negative electrode sheet 24, the first separator 71, and the second separator 72 are each prepared in a state of being wound around a reel (not shown) or the like. The positive electrode sheet 22, the negative electrode sheet 24, the first separator 71, and the second separator 72 are each transported along predetermined transport paths k1 to k4. The transport path k1 is a path along which the positive electrode sheet 22 is fed from a reel (not shown) toward the turret 220. The transport path k2 is a path along which the negative electrode sheet 24 is fed from a reel (not shown) toward the turret 220. The transport path k3 is a path along which the first separator 71 is fed from a reel (not shown) toward the turret 220. The transport path k4 is a path along which the second separator 72 is fed from a reel (not shown) toward the turret 220. The conveyance path k1 of the positive electrode sheet 22 preferably merges with the conveyance path k3 of the first separator 71 and the conveyance path k4 of the second separator 72 before reaching the winding core 241 arranged at the first position P1. The positive electrode sheet 22, the first separator 71, and the second separator 72 may be bonded together by adhesive layers (more specifically, the first adhesive layer 81 and the second adhesive layer 82) formed in an adhesive layer forming step described below. The conveyance path k1 of the negative electrode sheet 24 preferably merges with the conveyance path k4 of the second separator 72 before reaching the winding core 241 arranged at the first position P1. A dancer roll mechanism for removing slack in the positive electrode sheet 22, the negative electrode sheet 24, the first separator 71, and the second separator 72 being fed, a tensioner for adjusting tension, and the like may be appropriately disposed on each of the conveyance paths k1 to k4.

[0054] The turret 220 is a rotating disk with a rotation axis set at the center C1. As shown in FIG. 10, the turret 220 is provided with multiple (three in this embodiment) winding cores (a first winding core 241, a second winding core 242, and a third winding core 243). Note that, hereinafter, the first to third winding cores 241 to 243 will be referred to as winding cores 240 when they are not particularly distinguished from one another. Furthermore, when the first to third winding cores 241 to 243 are distinguished from one another, they will be appropriately distinguished as the first winding core 241, the second winding core 242, and the third winding core 243. The multiple winding cores 240 are each a substantially cylindrical shaft that can rotate independently. Here, the shafts of the multiple winding cores 240 are each arranged so as to be parallel to the central axis of the turret 220. The first winding core 241, the second winding core 242, and the third winding core 243 are arranged at equal intervals in the circumferential direction around the central axis of the turret 220. The first winding core to the third winding core 241 to 243 preferably have the same configuration. Although not shown, the turret 220 is equipped with a required actuator (for example, a servo motor) and rotates at an appropriate angle at an appropriate timing.

[0055] The turret 220 has a first position P1, a second position P2, and a third position P3 around its center C1. are set in advance. In FIG. 10, the first winding core 241 is disposed at the first position P1, the third winding core 243 is disposed at the second position P2, and the second winding core 242 is disposed at the third position P3. However, the positions of the first to third winding cores 241 to 243 are not fixed to the positions shown in FIG. 10. Here, the turret 220 rotates counterclockwise as indicated by the arrow. The first to third winding cores 241 to 243 also rotate counterclockwise as indicated by the arrow. The first to third winding cores 241 to 243 move sequentially between the first position P1, the second position P2, and the third position P3 as the turret 220 rotates. Although not shown, the first to third winding cores 241 to 243 are equipped with required actuators (for example, servo motors) and rotate at appropriate timing and speeds.

[0056] 11 is a cross-sectional view schematically showing the winding core 240 arranged at the first position P1. The winding core 240 is a substantially cylindrical member. In this embodiment, the winding core 240 is substantially cylindrical, but a flat winding core may be used when winding into a flat shape. The winding core may also be a winding core divided along the radial direction, and the diameter of the winding core may be variable.

[0057] FIG. 11 shows a view of the winding core 240 from the axial direction, and schematically illustrates the state in which the first separator 71 and the second separator 72 are wound around the winding core 240, which is positioned at the first position P1. The winding core 240 has a function of holding the first separator 71 and the second separator 72 wound around its side circumferential surface. Here, the winding core 240 has a suction hole 240a, a suction path 240b, and a groove 240c. The suction hole 240a is a hole for adsorbing the first separator 71 and / or the second separator 72 wound around its side circumferential surface. The suction hole 240a may have a circular or rectangular shape in a plan view. Alternatively, the suction hole 240a may be slit-shaped. The suction path 240b is a flow path formed inside the winding core 240 and connected to the suction hole 240a. The suction path 240b is a flow path for creating a negative pressure in the suction hole 240a. The suction path 240b may be configured to be connected to an external vacuum line (not shown), for example, as appropriate, to create a negative pressure. In this embodiment, the groove 240c is formed on the outer peripheral surface of the winding core 240 along the axial direction of the winding core 240. The groove 240c can function as a receiving portion onto which the blade 251a of the cutter 251 is lowered when the first separator 71 and the second separator 72 are cut in the cutting process described below. This prevents damage to the winding core 240 or the cutter 251 due to contact between the winding core 240 and the blade 251a of the cutter 251.

[0058] The cutter 251 is a cutter that cuts the first separator 71 and the second separator 72. The cutter 251 is an example of a cutting tool. The cutter 251 is preferably configured to cut the first separator 71 and the second separator 72 by pressing the blade 251a against the first separator 71 and the second separator 72 held by the winding core 240 arranged at the first position P1. The cutter 251 may be configured to be able to be pushed along a guide to a predetermined position where the blade 251a is pressed against the separators held by the winding core 240, and to be able to retract from that position. Although not shown, the cutter 251 is operated by an actuator (for example, a cylinder mechanism) so as to operate at an appropriate timing. The blade 251a may be, for example, a serrated blade (a saw-like blade).

[0059] The pressing jig 252 is a jig that presses the first separator 71 and the second separator 72 against the winding core 240 that is positioned at the first position P1. The first separator 71 and the second separator 72 are wound by the pressing jig 252 against the winding core 240 that is positioned at the first position P1. Although not particularly limited, the pressing jig 252 is preferably configured to press the fourth surface 72b of the second separator 72 immediately after the first separator 71 and the second separator 72 are wound around the winding core 240 (for example, after about one or two turns have been made). The pressing jig 252 may be configured to press the first separator 71 and the second separator 72 against the winding core 240 that is positioned at the first position P1 with an appropriate pressure, for example, by a mechanism that incorporates a spring or the like. Although not shown, the holding jig 252 is moved by a guide and an actuator between a position where it is pressed against the first separator 71 and the second separator 72 wound around the winding core 240 arranged at the first position P1, and a position where it is separated from the winding core 240. One holding jig 252 may be provided in the width direction of the winding core 240, or multiple holding jig 252 may be arranged intermittently in the width direction of the winding core 240.

[0060] The pressing jig 252 is preferably a roller, for example, as shown in FIG. 11 . More preferably, the pressing jig 252 is a roller having a plurality of protrusions 252a formed on its outer circumferential surface. When the two first and second separators 71 and 72 are pressed against the winding core 240 by the pressing jig 252 having the protrusions 252a, the force is locally concentrated by the protrusions 252a, and the first and second separators 71 and 72 are pressed firmly against each other. This allows the first and second separators 71 and 72 to be more effectively pressed against each other. The pressing roller is preferably, for example, substantially cylindrical, and has a knurled outer surface.

[0061] The plurality of rollers 261 to 264 are arranged on the transport paths k1 to k4 of the positive electrode sheet 22, the negative electrode sheet 24, the first separator 71, and the second separator 72, respectively. The plurality of rollers 261 to 264 are an example of a transport device. The plurality of rollers 261 to 264 are arranged at predetermined positions to define the respective transport paths k1 to k4. The positive electrode sheet 22, the negative electrode sheet 24, the first separator 71, and the second separator 72 are transported by the plurality of rollers 261 to 264, respectively.

[0062] As shown in Figure 10, the index unit 280 is provided in the center of the turret 220. As described above, the three winding cores 241 to 243 are evenly arranged around the turret 220. The index unit 280 has a substantially equilateral triangular base that rotates together with the turret 220. Index rollers 281 to 283 are arranged at the vertices of the base, and the index rollers 281 to 283 are respectively arranged between the three winding cores 241 to 243.

[0063] 12 shows a state in which the winding core (here, the first winding core 241) around which the positive electrode sheet 22 and the negative electrode sheet 24 are wound moves to the second position P2, a new winding core (here, the second winding core 242) moves to the first position P1, and the first separator 71 and the second separator 72 are cut. When the winding core 241 around which the positive electrode sheet 22, the first separator 71, the negative electrode sheet 24, and the second separator 72 are wound moves from the first position P1 to the second position P2, the index unit 280 has the index roller 281, of the index rollers 281 to 283, which is positioned between the first position P1 and the second position P2, press against the first separator 71 and the second separator 72 from their inner diameter sides, as shown in FIG. The index roller 281 and roller 266 allow the first separator 71 and the second separator 72 to be fed without slack between the first position P1 and the second position P2. At the timing shown in Fig. 12, the index roller 281 presses against the first separator 71 and the second separator 72 from the inner diameter side, but the index unit 280 rotates together with the rotation of the turret 220. Therefore, the index rollers 281 to 283 of the index unit 280 function in sequence as rollers that press against the first separator 71 and the second separator 72 from the inner diameter side when the winding core 240, on which the positive electrode sheet 22, the first separator 71, the negative electrode sheet 24, and the second separator 72 have been wound, moves from the first position P1 to the second position P2.

[0064] For example, as shown in FIG. 12 , the winding core 241, which has wound up the positive electrode sheet 22, the first separator 71, the negative electrode sheet 24, and the second separator 72, moves from the first position P1 to a second position P2 away from the first position P1. Then, after the first separator 71 and the second separator 72 are cut, the cut first separator 71 and the cut second separator 72 are wound up to the cut ends. The winding stop device 270 is disposed at the second position P2. The winding stop device 270 includes, for example, a pressure roller 271 and a tape application device 272. The pressure roller 271 is pressed against the outermost second separator 72 wound around the winding core 241 when the winding core 240, which has moved to the second position P2, winds up the cut positive electrode sheet 22, the first separator 71, the negative electrode sheet 24, and the second separator 72 up to the cut ends. As a result, the cut positive electrode sheet 22, first separator 71, negative electrode sheet 24, and second separator 72 are each wound up without loosening. The tape application device 272 is a device that applies tape to secure the cut end of the outermost second separator 72 or first separator 71. This winding stop process may be performed, for example, in parallel with the process of winding the first separator 71, positive electrode sheet 22, second separator 72, and negative electrode sheet 24 onto the winding core 242 newly placed at the first position P1.

[0065] In this embodiment, as shown in FIG. 12 , for example, the winding machine 200 performs a winding stop process and winds the positive electrode sheet 22, the first separator 71, the negative electrode sheet 24, and the second separator 72 onto the winding core 242 positioned at the first position P1, and then the turret 220 rotates. The winding core 241 on which the winding stop process has been performed moves to the third position P3, the winding core 242 moves to the second position P2, and another winding core is positioned at the first position P1. At this time, the first separator 71 and the second separator 72 wound onto the winding core 242 positioned at the second position P2 are held connected to each other on the outer peripheral surface of the winding core 243 positioned at the first position P1. Then, after the first separator 71 and the second separator 72 are cut, the winding stop process is performed on the winding core 242 at the second position P2. At the first position P1, the positive electrode sheet 22, the first separator 71, the negative electrode sheet 24, and the second separator 72 are newly wound around the winding core 243. At the third position P3, the wound body 20a is removed from the winding core 241. After being removed, the wound body 20a is pressed flat and can be handled as the wound electrode body 20. In this manner, the winding cores 241 to 243 provided on the turret 220 move sequentially between the first position P1 and the third position P3. The positive electrode sheet 22, the first separator 71, the negative electrode sheet 24, and the second separator 72 are then continuously wound around the winding cores 241 to 243 in that order.

[0066] The battery manufacturing method disclosed herein includes at least an adhesive layer forming step and a wound electrode body fabricating step. The adhesive layer forming step is a step of forming a first adhesive layer 81 on the surface of at least one of the positive electrode sheet 22 and the first separator 71, and forming a second adhesive layer 82 on the surface of at least one of the positive electrode sheet 22 and the second separator 72. The wound electrode body fabrication process is a process of fabricating the wound electrode body 20 by winding a strip-shaped first separator 71, a strip-shaped positive electrode sheet 22, a strip-shaped second separator 72, and a strip-shaped negative electrode sheet 24. In the battery manufacturing method disclosed herein, the wound electrode body fabrication process is performed immediately after the adhesive layer formation process. This allows for control of the position where the adhesive layer is formed, allowing the adhesive layer to be positioned more appropriately in the wound electrode body 20. Furthermore, the positive electrode sheet 22, the first separator 71, and the second separator 72, on which the adhesive layer is formed, are continuously fed onto a winding core without being wound onto a reel or the like, to fabricate the wound electrode body 20. Therefore, the wound electrode body 20 is fabricated immediately after the adhesive layer is formed. This allows for fabrication of a wound electrode body 20 in which the positive electrode sheet 22, the first separator 71, and the second separator 72 are bonded with higher quality. This allows for the provision of a highly reliable battery 100, in which the shape stability of the wound electrode body 20 is high.

[0067] As described above, the manufacturing method disclosed herein is characterized in that the wound electrode body fabrication step is performed immediately after the adhesive layer formation step. Note that the manufacturing method disclosed herein is characterized in that the wound electrode body fabrication step is performed immediately after the adhesive layer formation step, and the remaining manufacturing processes may be the same as conventional ones. Furthermore, other steps may be included at any stage.

[0068] As shown in FIG. 9 , in the manufacturing method disclosed herein, a first adhesive layer 81 is formed on a first separator 71 and a second adhesive layer 82 is formed on a second separator 72, for example, by a coating device 150. After that, the first separator 71 and the second separator 72 are wound around a winding machine 200 (more specifically, a winding core 240) to produce a wound electrode body 20 without being wound around a reel or the like. That is, the adhesive layer forming process and the electrode body producing process are performed consecutively while the first separator 71 and the second separator 72 are transported along transport paths k3 and k4. This makes it possible to produce a wound electrode body 20 with high-quality adhesive layers at desired positions. Therefore, the positive electrode sheet 22, the first separator 71, and the second separator 72 are suitably bonded to each other, making it possible to provide a highly reliable battery 100.

[0069] Preferably, the distance between the position where the adhesive layer is formed and the position where the wound electrode body 20 is produced is less than 50 m. For example, as shown in FIG. 9, the coating device 150 that forms the adhesive layer and the winding machine 200 that produces the wound electrode body 20 are preferably installed at positions less than 50 m apart, and may be installed at positions less than 10 m or less than 3 m. Furthermore, the time from when the adhesive layer is formed on the positive electrode sheet 22 and / or separator to when winding to produce the wound electrode body 20 begins is preferably less than 60 minutes, and may be less than 20 minutes or less than 5 minutes. The positions where the adhesive layer is formed and the position where the wound electrode body 20 is produced can be changed as appropriate depending on, for example, the desired thickness and type of adhesive layer.

[0070] 9, in the adhesive layer forming step, a first adhesive layer 81 and a second adhesive layer 82 are formed using an applicator 150. For example, a first applicator 150a for forming the first adhesive layer 81 and a second applicator 150b for forming the second adhesive layer 82 are arranged on one side of a vertical line L1 that passes through the center C2 of the winding core 242 and extends in the vertical direction. In the manufacturing method disclosed herein, the first adhesive layer 81 and the second adhesive layer 82 are formed so that one surface of the positive electrode sheet 22 and one surface of the first separator 71 are bonded by the first adhesive layer 81, and the other surface of the positive electrode sheet 22 and one surface of the second separator 72 are bonded by the second adhesive layer 82. For example, the first adhesive layer 81 is formed on the surface of the first separator 71 that faces the positive electrode sheet 22 (here, the first surface 71a). Alternatively, the first adhesive layer 81 is formed on the surface of the positive electrode sheet 22 that faces the first separator 71. The second adhesive layer 82 is formed on the surface of the second separator 72 that faces the positive electrode sheet 22 (here, the third surface 72a). Alternatively, the second adhesive layer 82 is formed on the surface of the positive electrode sheet 22 that faces the second separator 72. That is, the first adhesive layer 81 and the second adhesive layer 82 may be formed on both surfaces of the positive electrode sheet 22, respectively.

[0071] From the viewpoint of maintaining the formed adhesive layer in a more suitable state, it is preferable that the adhesive layer be formed on a surface that does not come into contact with the plurality of rollers 261 to 264. Therefore, for example, it is preferable that the first adhesive layer 81 be formed on the first surface 71a of the first separator 71, and the second adhesive layer 82 be formed on the third surface 72a of the second separator 72. Alternatively, it is preferable that the first adhesive layer 81 be formed on the first surface 71a of the first separator 71, and the second adhesive layer 82 be formed on the surface of the positive electrode sheet 22 that faces the second separator 72.

[0072] The method for forming the adhesive layer is not particularly limited. For example, the adhesive layer can be formed by applying a binder liquid from a coating device 150 along the conveyance direction of the positive electrode sheet 22, the first separator 71, and the second separator 72. The binder liquid contains, for example, the adhesive layer binder described above and a solvent. From the viewpoint of reducing environmental impact, a so-called aqueous solvent is preferably used as the solvent for the binder liquid. In this case, water or a mixed solvent mainly containing water can be used. As the solvent component other than water constituting such a mixed solvent, one or more organic solvents (lower alcohols, lower ketones, etc.) that are uniformly miscible with water can be appropriately selected and used. For example, it is preferable to use an aqueous solvent in which 80% by mass or more (more preferably 90% by mass or more, and even more preferably 95% by mass or more) of the aqueous solvent is water. A particularly preferred example is an aqueous solvent that is essentially composed of water. The solvent for the binder liquid is not limited to a so-called aqueous solvent, but may also be a so-called organic solvent. Examples of organic solvents include N-methylpyrrolidone. For example, a suitable example of the binder liquid is one in which water is used as a solvent and an acrylic resin (e.g., polymethacrylic acid ester resin) is mixed as a binder. Note that the binder liquid may contain one or more additives such as known thickeners or surfactants for the purpose of improving wettability with respect to the positive electrode sheet 22 and the separator, as long as the effects of the technology disclosed herein are not impaired.

[0073] The binder liquid is applied in a predetermined pattern to desired regions along the longitudinal direction of the positive electrode sheet 22, the first separator 71, and the second separator 72. The method for applying the binder liquid is not particularly limited, and various coating machines, printing machines, etc. can be used. Specific examples that can be used include inkjet printing, various intaglio printing machines such as gravure roll coaters, spray coaters, slit coaters, comma coaters, capillary coaters (CAP coaters), and other die coaters, and lip coaters.

[0074] Although not particularly limited, in the wound electrode assembly fabrication process described below, it is preferable to apply a binder liquid to the region that contacts the winding core 240 so that the basis weight of the adhesive layer is small. For example, it is preferable that the basis weight of the region of the second surface 71b of the first separator 71 that contacts the winding core 240 is smaller than the basis weight of the same region of the first surface 71a. More preferably, as shown in FIG. 11 , an adhesive layer is not formed in the region of the second surface 71b of the first separator 71 that contacts the winding core 240. Also, although not shown, it is preferable that the basis weight of the region of the fourth surface 72b of the second separator 72 that contacts the winding core 240 is smaller than the basis weight of the same region of the third surface 72a. More preferably, it is preferable that an adhesive layer is not formed in the region of the fourth surface 72b of the second separator 72 that contacts the winding core 240. This allows the wound electrode assembly 20 to be conveniently removed from the winding core 240.

[0075] Furthermore, when the wound electrode body 20 is produced, it is preferable to apply a binder liquid to the surface that will become the outermost periphery so that the basis weight of the adhesive layer is small. Specifically, on the fourth surface 72b of the second separator 72, the basis weight of the adhesive layer in a region that corresponds to the outermost periphery is preferably smaller than the basis weight of the same region on the third surface 72a. More preferably, on the fourth surface 72b of the second separator 72, no adhesive layer is formed in a region that corresponds to the outermost periphery. Also, on the second surface 71b of the first separator 71, the basis weight of the adhesive layer in a region that corresponds to the outermost periphery is preferably smaller than the basis weight of the same region on the first surface 71a. More preferably, on the second surface 71b of the second separator 72, no adhesive layer is formed in a region that corresponds to the outermost periphery. This improves the handleability of the wound electrode body 20, for example, allowing the wound electrode body 20 to be smoothly accommodated in the electrode body holder 29.

[0076] Although not particularly limited, it is preferable to form the first adhesive layer 81 on the first separator 71 when passing through a region of ±30° with respect to the vertical line L1 on the conveying path k3, and it is preferable to form the second adhesive layer 82 on the second separator 72 when passing through a region of ±30° with respect to the vertical line L1 on the conveying path k4. In other words, it is preferable to arrange the first coating device 150a in a region of ±30° with respect to the vertical line L1 on the conveying path k3, and it is preferable to arrange the second coating device 150b in a region of ±30° with respect to the vertical line L1 on the conveying path k4. This can improve, for example, coating unevenness in the width direction of the separator, and form a more uniform adhesive layer. It is preferable to form the adhesive layer when passing through a region of ±15° with respect to the vertical line L1 on the conveying path, and more preferably, it is preferable to form the adhesive layer when passing through a region of approximately vertical with respect to the vertical line L1 on the conveying path.

[0077] Furthermore, although not particularly limited, in the adhesive layer forming step, it is preferable that an adhesive layer be formed on the surface that does not come into contact with the plurality of rollers 261 to 264. For example, it is preferable that the first adhesive layer 81 be formed on the surface of the first separator 71 that does not come into contact with the roller 263. It is also preferable that the first adhesive layer 81 and / or the second adhesive layer 82 be formed on the surface of the positive electrode sheet 22 that does not come into contact with the roller 261. It is also preferable that the second adhesive layer 82 be formed on the surface of the second separator 72 that does not come into contact with the roller 264. This allows the wound electrode body fabrication step to be carried out while the formed adhesive layer is favorably maintained.

[0078] In the wound electrode assembly fabrication step, a strip-shaped first separator 71, a strip-shaped positive electrode sheet 22, a strip-shaped second separator 72, and a strip-shaped negative electrode sheet 24 are wound to fabricate the wound electrode assembly 20. This wound electrode assembly fabrication step can be preferably performed using, for example, the winding machine 200 described above. When winding using such a winding machine 200, as shown in FIG. 9, the first separator 71, the positive electrode sheet 22, the second separator 72, and the negative electrode sheet 24 are supplied to the winding core 240 from one side of the vertical line L1. The arrangement of the components is not particularly limited, but it is preferable that the first separator 71, the positive electrode sheet 22, the second separator 72, and the negative electrode sheet 24 are arranged from below in this order and supplied to the winding machine 200 (more specifically, the winding core 240) as shown in FIG. 9.

[0079] The angle at which the positive electrode sheet 22 is supplied to the winding core 240 is preferably smaller than the angle at which the negative electrode sheet 24 is supplied to the winding core 240. Here, "the angle at which the positive electrode sheet is supplied to the winding core" refers to the angle with respect to a horizontal line L2 that passes through the center C2 of the winding core 242 and extends horizontally. Also, "the angle at which the negative electrode sheet is supplied to the winding core" refers to the angle with respect to the horizontal line L2. As shown in FIG. 9 , the angle at which the positive electrode sheet 22 is supplied to the winding core 240 is preferably approximately horizontal (i.e., 0°) with respect to the horizontal line L2, and the angle at which the negative electrode sheet 24 is supplied may be larger. In general, the positive electrode sheet 22 is less flexible than the negative electrode sheet 24. Therefore, by reducing the angle at which the positive electrode sheet is supplied to the winding core 240 (the angle with respect to the horizontal direction), the positive electrode sheet 22 can be wound in a state of higher quality.

[0080] 10, the first separator 71, the positive electrode sheet 22, the second separator 72, and the negative electrode sheet 24, which have been transported along predetermined transport paths k1 to k4, are wound around a winding core 240 disposed at a first position P1. At this time, as shown in FIG. 11, the first separator 71 and the second separator 72 are preferably wound around the winding core 241 such that the second surface 71b of the first separator 71 abuts against the winding core 240 and the first surface 71a of the first separator 71 abuts against the third surface 72a of the second separator 72. Although not particularly limited, it is preferable that the first surface 71a of the first separator 71 and the third surface 72a of the second separator 72 are bonded by at least one of a first adhesive layer 81 and a second adhesive layer 82. This allows the positive electrode sheet 22, the first separator 71, and the second separator 72 to be wound around the winding core 240 in a state where they are properly bonded together.

[0081] 11 , in the winding start region of the wound electrode body 20, the first separator 71 and the second separator 72 may be wound around the winding core 240 without the positive electrode sheet 22 interposed therebetween. In this case, the first surface 71a of the first separator 71 and the third surface 73a of the second separator 72 are preferably bonded together by only one of the first adhesive layer 81 and the second adhesive layer 82. Although not shown, when the first adhesive layer 81 is formed on the first surface 71a of the first separator 71 and the second adhesive layer 82 is formed on the surface of the positive electrode sheet 22 facing the second separator 72, it is preferable that the first surface 71a of the first separator 71 and the third surface 72a of the second separator 72 are bonded together by the first adhesive layer 81 in the opposing region without the positive electrode sheet 22 interposed therebetween. Furthermore, although not shown, when a first adhesive layer 81 is formed on the surface of the positive electrode sheet 22 facing the first separator 71 and a second adhesive layer 82 is formed on the third surface 72a of the second separator 72, it is preferable that the first surface 71a of the first separator 71 and the third surface 72a of the second separator 72 are bonded by the second adhesive layer 82 in the region that faces each other without the positive electrode sheet 22 in between. This ensures favorable bonding at the start of winding during winding, making it possible to prevent misalignment during winding and the like. Furthermore, the thickness of the electrode body can be reduced without reducing the battery capacity.

[0082] In the manufacturing method disclosed herein, a winding core 240 having a plurality of suction holes 240a may be used as the winding core 240, as shown in FIG. 11 . Although not particularly limited, in the wound electrode assembly manufacturing process, it is preferable to fix the second surface 71b of the first separator 71 to the winding core 240 by suction. More preferably, as shown in FIG. 11 , the first separator 71 and the second separator 72 are preferably suctioned and fixed in a stacked state. At this time, if an adhesive layer is formed on the first surface 71a of the first separator 71 and / or the third surface 72a of the second separator 72, the first separator 71 and the second separator 72 can be fixed to the winding core 240 in a suitably bonded state. As described above, the first separator 71 and the second separator 72 are porous. Therefore, suction by suction holes 240a of winding core 240 is effectively exerted, and first separator 71 and / or second separator 72 can be fixed onto the outer peripheral surface of winding core 240.

[0083] The wound electrode body fabrication process preferably includes a cutting process in which the first separator 71 and the second separator 72 are cut while they are stacked. In this cutting process, a cutting tool (cutter 251 in this case) is pressed against the first separator 71 and the second separator 72 that are stacked and held on the winding core 240, to cut the first separator 71 and the second separator 72. At this time, as shown in Fig. 12, the first separator 71 and the second separator 72 that have been wound around a winding core (winding core 241 in this case) that is further away from the first position P1 are preferably cut on or near another winding core (winding core 242 in this case) that is arranged at the first position P1, while being held in a state where they are stacked on the outer peripheral surface of that other winding core. That is, the cut portions of the first separator 71 and the second separator 72 become the winding end of the previous wound body (here, wound body 20a wound around winding core 241) and also become the winding start end of the next wound body. This allows the next wound body to be produced continuously after the first separator 71 and the second separator 72 are cut, improving productivity.

[0084] Although not particularly limited, it is preferable that the basis weight of the first adhesive layer 81 in the region of the first separator 71 that is cut in the cutting process is smaller than the basis weight of the first adhesive layer 81 in the region facing the positive electrode sheet 22. For example, the basis weight E (g / m 2 ) of the first adhesive layer 81 in the area to be cut by the cutting process. 2 ) is preferably 0.5 or less, and may be 0.25 or less. More preferably, the first adhesive layer 81 is not formed in the region of the first separator 71 that will be cut in the cutting process. This allows the first separator 71 to be cut stably.

[0085] Furthermore, although not particularly limited, it is preferable that the basis weight of the second adhesive layer 82 in the region of the second separator 72 that will be cut in the cutting process be smaller than the basis weight of the second adhesive layer 82 in the region facing the positive electrode sheet 22. For example, the basis weight G (g / m 2 ) of the second adhesive layer 82 in the area to be cut by the cutting process. 2 ) is preferably 0.5 or less, and may be 0.25 or less. More preferably, the second adhesive layer 82 is not formed in the region of the second separator 72 that will be cut in the cutting process. This allows the first separator 71 and the second separator 72 to be cut stably even when the first separator 71 and the second separator 72 are sucked onto the winding core 240 in a stacked state. The basis weight of the areas of the first separator 71 and the second separator 72 that are cut by the cutting process can be controlled by reducing the amount of binder liquid applied to the areas to be cut in the adhesive layer formation process described above, or by not applying binder liquid at all.

[0086] The wound body 20a produced using the above-described winding machine 200 is removed from the winding core 240, and the wound body 20a is pressed flat to produce the wound electrode body 20. The prepared wound electrode body 20 is then inserted into the battery case 10 and sealed, thereby producing the battery 100.

[0087] For example, as shown in FIG. 6, a positive electrode second current collecting member 52 is joined to the positive electrode tab group 25 of the wound electrode body 20, and a negative electrode second current collecting member 62 is joined to the negative electrode tab group 27. Then, as shown in FIG. 5, multiple (three in this example) wound electrode bodies 20 are arranged so that the flat portions 20f face each other. A sealing plate 14 is placed above the multiple wound electrode bodies 20, and the positive electrode tab group 25 of each wound electrode body 20 is bent so that the positive electrode second current collecting member 52 faces one side surface 20e of the wound electrode body 20. This connects the positive electrode first current collecting member 51 and the positive electrode second current collecting member 52. Similarly, the negative electrode tab group 27 of each wound electrode body 20 is bent so that the negative electrode second current collecting member 62 faces the other side surface 20h of the wound electrode body 20. This connects the negative electrode first current collecting member 61 and the negative electrode second current collecting member 62. As a result, the wound electrode body 20 is attached to the sealing plate 14 via the positive electrode current collecting part 50 and the negative electrode current collecting part 60. Next, the wound electrode body 20 attached to the sealing plate 14 is covered with an electrode body holder 29 (see FIG. 3 ) and then housed inside the exterior body 12. As a result, the flat portion 20f of the wound electrode body 20 faces the long side wall 12b of the exterior body 12 (i.e., the flat surface of the battery case 10). In addition, the upper curved portion 20r faces the sealing plate 14, and the lower curved portion 20r faces the bottom wall 12a of the exterior body 12. Then, after the opening 12h on the top surface of the exterior body 12 is closed with the sealing plate 14, the exterior body 12 and the sealing plate 14 are joined (welded) to construct the battery case 10. Thereafter, the electrolyte is injected into the battery case 10 through the injection hole 15 of the sealing plate 14, and the injection hole 15 is closed with the sealing member 16. In this manner, the battery 100 can be manufactured.

[0088] In the above-described embodiment, the wound electrode body 20 is disposed inside the exterior housing 12 with the winding axis WL parallel to the long-side direction Y of the exterior housing 12. However, the wound electrode body may also be disposed inside the exterior housing 12 with the winding axis WL parallel to the up-down direction Z of the exterior housing 12. FIG. 13 is a diagram corresponding to FIG. 2 of a battery 400 according to the second embodiment. As shown in FIG. 13, the battery 400 includes a wound electrode body 420 instead of the wound electrode body 20. In the battery 400, the arrangement of the wound electrode body 420 differs from that of the first embodiment. Therefore, the battery 400 includes a positive electrode tab group 425 and a negative electrode tab group 427 instead of the positive electrode tab group 25 and the negative electrode tab group 27. The battery 400 includes a positive electrode current collector 450 and a negative electrode current collector 460 instead of the positive electrode current collector 50 and the negative electrode current collector 60. The battery 400 includes an internal insulating member 494 instead of the internal insulating member 94. Other than these, the battery 400 may be similar to the battery 100 of the first embodiment described above. According to the manufacturing method disclosed herein, the battery 400 of the second embodiment can also be suitably manufactured by substantially the same method as the battery 100 of the first embodiment.

[0089] The wound electrode body 420 is accommodated inside the battery case 10 so that the winding axis WL here substantially coincides with the up-down direction Z. In other words, the wound electrode body 420 is disposed inside the battery case 10 with the winding axis WL substantially parallel to the long side wall and the short side wall 12c and substantially perpendicular to the bottom wall 12a and the sealing plate 14. The pair of curved portions face the short side walls 12c of the exterior body 12. The pair of flat portions face the long side walls of the exterior body 12. The end faces of the wound electrode body 420 (i.e., the stacking surfaces where the positive electrode sheet 22 and the negative electrode sheet 24 are stacked) face the pair of bottom walls 12a and the sealing plate 14. The materials, configurations, etc. of the components constituting the wound electrode body 420 may be the same as those of the wound electrode body 20 of the first embodiment.

[0090] The positive electrode tab group 425 and the negative electrode tab group 427 are provided at one end (the upper end in FIG. 13 ) in the up-down direction Z of the wound electrode body 420. A positive electrode current collector 450 is attached to the positive electrode tab group 425. The positive electrode tab group 425 is electrically connected to the positive electrode terminal 30 via the positive electrode current collector 450. A negative electrode current collector 460 is attached to the negative electrode tab group 427. The negative electrode tab group 427 is electrically connected to the negative electrode terminal 40 via the negative electrode current collector 460.

[0091] <Battery uses> The above-mentioned battery can be used for various purposes, and can be suitably used, for example, as a power source (driving power source) for motors mounted on vehicles such as passenger cars and trucks. The type of vehicle is not particularly limited, and examples include plug-in hybrid electric vehicles (PHEVs), hybrid electric vehicles (HEVs), and battery electric vehicles (BEVs). The battery can also be suitably used in the construction of assembled batteries.

[0092] Although several embodiments of the present invention have been described above, the above embodiments are merely examples. The present invention can be implemented in various other forms. The present invention can be implemented based on the contents disclosed in this specification and the common general technical knowledge in the relevant field. The technology described in the claims includes various modifications and alterations of the above-exemplified embodiments. For example, it is possible to replace part of the above-described embodiments with other modified embodiments, and it is also possible to add other modified embodiments to the above-described embodiments. Furthermore, if a technical feature is not described as essential, it may be deleted as appropriate.

[0093] For example, a drying step may be included after the adhesive layer forming step and before the wound electrode body fabricating step. In this drying step, the solvent of the binder liquid applied to the positive electrode sheet 22, the first separator 71, and the second separator 72 is removed. The drying method is not particularly limited, and methods such as ventilation drying, heat drying, and vacuum drying can be used. Note that the drying step is not an essential step and can be omitted as appropriate.

[0094] Furthermore, for example, in the above example, the wound electrode body 20 was produced using a winding machine 200 as shown in FIG. 10 . However, the winding machine is not limited to this. FIG. 14 is a diagram showing another example of a winding machine. As shown in FIG. 14 , the wound electrode body 20 can also be produced using a winding machine 500 having a first slit S1 and a second slit S2 in a substantially cylindrical winding core. The first slit S1 and the second slit S2 are arranged at positions 180° apart around the winding axis of the winding core 540. To produce the wound electrode body 20, the leading edge of the first separator 71 is sandwiched in one of the first slit S1 and the second slit S2 of the winding core 540, and the leading edge of the second separator 72 is sandwiched in the other. Then, the winding core 540 is slightly wound, and the leading edge of the positive electrode sheet 22 is inserted between the second separator 72 wound around the winding core 540 and the first separator 71 wound around the winding core 540. Furthermore, the leading end of the negative electrode sheet 24 is inserted between the first separator 71 wound around the winding core 540 and the second separator 72 wound around the winding core 540. Thereafter, the winding core 540 is further rotated to wind up the first separator 71, the positive electrode sheet 22, the second separator 72, and the negative electrode sheet 24. The cylindrical wound body wound around the winding core 540 is then removed from the winding core and pressed flat, thereby producing the wound electrode body 20.

[0095] As described above, specific aspects of the technology disclosed herein include those described in the following sections. Item 1: A method for manufacturing a battery comprising a wound electrode body formed by winding a strip-shaped first separator, a strip-shaped positive electrode sheet, a strip-shaped second separator, and a strip-shaped negative electrode, wherein the positive electrode sheet and the first separator are bonded together with a first adhesive layer, and the positive electrode sheet and the second separator are bonded together with a second adhesive layer, the method comprising: an adhesive layer forming step of forming the first adhesive layer on at least one surface of the positive electrode sheet and the first separator, and forming the second adhesive layer on at least one surface of the positive electrode sheet and the second separator; and a wound electrode body fabricating step of fabricating a wound electrode body by winding the strip-shaped first separator, the strip-shaped positive electrode sheet, the strip-shaped second separator, and the strip-shaped negative electrode. Item 2: A manufacturing method according to item 1, wherein the first separator has a first surface and a second surface, the second separator has a third surface and a fourth surface, the first adhesive layer is formed on the first surface of the first separator, and the second adhesive layer is formed on the third surface of the second separator, and the wound electrode body manufacturing step involves winding the first separator and the second separator around the winding core such that the second surface of the first separator abuts against the winding core and the first surface of the first separator abuts against the third surface of the second separator. Item 3: The manufacturing method according to Item 2, wherein the first surface of the first separator and the third surface of the second separator are bonded together by at least one of the first adhesive layer and the second adhesive layer. Item 4: The manufacturing method according to Item 2, wherein in a region where the first separator and the second separator face each other without the positive electrode sheet in between, the first surface of the first separator and the third surface of the second separator are bonded by only one of the first adhesive layer and the second adhesive layer. Item 5: The manufacturing method according to any one of Items 2 to 4, wherein in the wound electrode body fabrication step, the second surface of the first separator is fixed by being attracted to the winding core. Item 6: The manufacturing method according to any one of Items 2 to 5, wherein the wound electrode body fabrication step includes a cutting process in which the first separator and the second separator are arranged in a stacked state on the outer peripheral surface of the winding core, and a cutting jig is pressed against the first separator and the second separator, thereby cutting the first separator and the second separator. Item 7: The manufacturing method according to Item 6, wherein the basis weight of the first adhesive layer in the region of the first separator that is cut in the cutting process is smaller than the basis weight of the first adhesive layer formed in the region of the first separator that faces the positive electrode sheet. Item 8: The manufacturing method according to Item 6 or 7, wherein the first adhesive layer is not formed in the area of ​​the first separator that will be cut in the cutting process. Item 9: A manufacturing method according to any one of items 1 to 8, wherein in the adhesive layer forming step, the first adhesive layer is formed on the first separator when the first separator passes through a region of ±30° relative to the vertical direction in a transport path along which the first separator is transported, and the second adhesive layer is formed on the second separator when the second separator passes through a region of ±30° relative to the vertical direction in a transport path along which the second separator is transported. Item 10: The manufacturing method according to any one of Items 1 to 9, wherein in the adhesive layer forming step, the first adhesive layer is applied to a surface of the first separator that does not come into contact with a conveying device, and a second adhesive layer is applied to a surface of the positive electrode sheet that does not come into contact with a conveying device. [Explanation of symbols]

[0096] 10 Battery case 12 Exterior body 14 Sealing plate 20 Wound electrode body 20a wound body 22 Positive electrode sheet 24 Negative electrode sheet 30 Positive terminal 40 Negative terminal 50 Positive electrode current collector 60 Negative electrode current collector 71 First separator 71a 1st page 71b 2nd side 72 Second separator 72a 3rd page 72b Side 4 81 1st adhesive layer 82 Second adhesive layer 100 batteries 150 Coating equipment 200 Winding machine 220 Turret 240 core 240a Suction hole 240b Suction path 240c groove 251 Cutter 252 Presser jig 270 Winding stop device 280 Index Unit 300 control device 400 batteries 420 Wound electrode body

Claims

1. a wound electrode body in which a strip-shaped first separator, a strip-shaped positive electrode sheet, a strip-shaped second separator, and a strip-shaped negative electrode sheet are wound together; a method for manufacturing a battery in which the positive electrode sheet and the first separator are bonded together by a first adhesive layer, and the positive electrode sheet and the second separator are bonded together by a second adhesive layer, an adhesive layer forming step of forming the first adhesive layer on a surface of the first separator and forming the second adhesive layer on a surface of the second separator; a wound electrode body fabrication step of fabricating a wound electrode body by winding the strip-shaped first separator, the strip-shaped positive electrode sheet, the strip-shaped second separator, and the strip-shaped negative electrode sheet around a winding core; Including, the adhesive layer forming step is performed on the strip-shaped first separator and the strip-shaped second separator being transported toward the winding core, the adhesive layer forming step is followed by the wound electrode body fabricating step without winding up the first separator and the second separator.

2. the wound electrode body fabrication step includes a cutting process of cutting a portion of the first separator that will become a winding end end, 2. The manufacturing method according to claim 1, wherein a basis weight of the first adhesive layer in a region of the first separator that is cut in the cutting process is smaller than a basis weight of the first adhesive layer formed in a region of the first separator that faces the positive electrode sheet.

3. The manufacturing method according to claim 2 , wherein the first adhesive layer is not formed in an area of ​​the first separator that is to be cut in the cutting process.

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