Battery

Abstract

To provide a technology capable of obtaining a wound electrode body with ease.SOLUTION: A battery 100 comprises a wound electrode body 20 configured by winding a belt-like positive electrode 22 and a belt-like negative electrode 24 via a belt-like separator 70 in a predetermined winding direction D1 around a winding shaft WL. A first separator 70A and a second separator 70B are provided as a separator 70. The second separator 70B has a region located outside a winding terminal end part 70a2 of the first separator. The second separator 70B has an extension part 28 extended from the winding terminal end part 70a2 of the first separator in the winding direction D1. A second adhesive layer 74b2 is formed at least at a part of a surface inside the extension part 28. The extension part 28 and a region S located inside the extension part 28 in the second separator 70B are adhered with each other with the second adhesive layer 74b2.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present disclosure relates to batteries. [Background technology]

[0002] For example, the following Patent Document 1 discloses a wound electrode body in which a negative electrode sheet, a first separator sheet, a positive electrode sheet, and a second separator sheet are wound together. It is described that such a wound electrode body can be manufactured using an electrode manufacturing device equipped with a winding roller. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6260608 Summary of the Invention [Problem to be solved by the invention]

[0004] In the manufacture of a wound electrode assembly, a stop tape is used to fix the end of the separator to the wound assembly, but the mechanism for applying the stop tape tends to complicate the configuration of the electrode manufacturing device. Therefore, there is a need for further development of a technology that can easily obtain a wound electrode assembly.

[0005] The present disclosure has been made in consideration of the above circumstances, and a main object of the present disclosure is to provide a technique that can easily obtain a wound electrode body. [Means for solving the problem]

[0006] In order to achieve this objective, the present disclosure provides a battery including a wound electrode body in which a strip-shaped positive electrode and a strip-shaped negative electrode are wound in a predetermined winding direction around a winding axis via a strip-shaped separator, the battery including a first separator and a second separator as the separators, the second separator having a region located outside the winding end end of the first separator, the second separator having an extension portion that extends beyond the winding end end of the first separator in the winding direction, a second adhesive layer being formed on at least a portion of the inner surface of the extension portion, and the extension portion and a region of the second separator located inside the extension portion being adhered by the second adhesive layer.

[0007] According to the present disclosure, in the manufacture of a wound electrode assembly, the winding end end of the separator can be suitably fixed to the wound body. That is, a technique can be provided that can easily obtain a wound electrode assembly. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing a battery according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a schematic vertical cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 2 is a schematic cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a schematic vertical cross-sectional view taken along line IV-IV in FIG. 2. [Figure 5A] FIG. 2 is a schematic diagram showing the configuration of a wound electrode body according to one embodiment. [Figure 5B] FIG. 2 is a schematic diagram showing a wound electrode body according to one embodiment. [Figure 6A] FIG. 6 is a schematic vertical cross-sectional view taken along line VI-VI in FIG. 5B. [Figure 6B] FIG. 6 is a schematic vertical cross-sectional view taken along line VI-VI in FIG. 5B. [Figure 6C] FIG. 6 is a schematic vertical cross-sectional view taken along line VI-VI in FIG. 5B. [Figure 7] FIG. 6B is an enlarged view of the dashed frame in FIG. 6A. [Figure 8] FIG. 6B is an enlarged view of the area enclosed by the dashed dotted line in FIG. 6A. [Figure 9] FIG. 6B is an enlarged view of the solid-line frame in FIG. 6A. [Figure 10] FIG. 2 is a schematic diagram showing the configurations of a first separator and a second separator according to one embodiment. [Figure 11] 5A to 5C are explanatory diagrams for explaining a manufacturing method of a wound electrode body according to one embodiment. [Figure 12] FIG. 11 is a schematic diagram showing the configurations of a first separator and a second separator according to a second embodiment. [Figure 13] FIG. 11 is a schematic diagram showing the configurations of a first separator and a second separator according to a third embodiment. [Figure 14] FIG. 13 is a schematic diagram showing the configurations of a first separator and a second separator according to a fourth embodiment. [Figure 15] FIG. 13 is a schematic diagram showing the configurations of a first separator and a second separator according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, some 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 and necessary for implementing the technology disclosed herein (for example, the general configuration and manufacturing process of a battery that does not characterize the present invention) can be understood as design matters of a person skilled in the art based on the conventional technology in the field. The technology disclosed here can be implemented based on the contents disclosed in this specification and the technical common sense in the field. It should be noted that the expression "A to B" indicating a range in this specification includes the meaning of "A or more and B or less", as well as "greater than A" and "less than B".

[0010] In this specification, the term "battery" refers to a general term for an electricity storage device capable of extracting electric energy, and is a concept that includes primary batteries and secondary batteries. In addition, in this specification, the term "secondary battery" refers to a general electricity 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. The electrolyte may be any of a liquid electrolyte (electrolytic solution), a gel electrolyte, and a solid electrolyte. Such secondary batteries include so-called storage batteries (chemical batteries) such as lithium ion secondary batteries and nickel metal hydride batteries, as well as capacitors (physical batteries) such as electric double layer capacitors. In the following, an embodiment in which a lithium ion secondary battery is the subject will be described.

[0011] FIG. 1 is a perspective view showing a battery 100 according to the first embodiment. The battery 100 is preferably a secondary battery, and more preferably a nonaqueous electrolyte secondary battery such as a lithium ion secondary battery. FIG. 2 is a schematic longitudinal sectional view taken along line II-II in FIG. 1. FIG. 3 is a schematic transverse sectional view taken along line III-III in FIG. 1. FIG. 4 is a schematic longitudinal sectional view taken along line IV-IV in FIG. 2. 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 100, the symbol Y indicates the long side direction of the battery 100, and the symbol Z indicates the up-down direction of the battery 100. However, these are merely directions for convenience of description, and do not limit the installation form of the battery 100 in any way. In addition, D1 in the drawings indicates the winding direction, but it is not intended to limit the winding direction to such a direction.

[0012] As shown in Figs. 1 to 3, the battery 100 includes a battery case 10 (see Fig. 1), a plurality of wound electrode assemblies 20 (see Figs. 2 and 3), a positive electrode terminal 30 (see Figs. 1 and 2), a negative electrode terminal 40 (see Figs. 1 and 2), a positive electrode current collector 50 (see Fig. 2), and a negative electrode current collector 60 (see Fig. 2). Although not shown, the battery 100 further includes an electrolyte. The battery 100 is a nonaqueous electrolyte secondary battery. The specific configuration of the battery 100 will be described below.

[0013] The battery case 10 is a housing that houses the wound electrode body 20. As shown in FIG. 1, the battery case 10 has a flat, bottomed rectangular parallelepiped (rectangular) outer shape. The material of the battery case 10 may be the same as that used conventionally, and is not particularly limited. The battery case 10 is preferably made of a metal, and more preferably made of, for example, aluminum, an aluminum alloy, iron, an iron alloy, or the like. As shown in FIG. 2, the battery case 10 includes an exterior body 12 having an opening 12h, and a sealing plate (lid body) 14 that seals the opening 12h. The exterior body 12 and the sealing plate 14 have sizes according to the number of wound electrode bodies 20 to be housed (one or more; here, more than one), the size, and the like.

[0014] As can be seen from Figs. 1 and 2, the exterior body 12 is a bottomed, rectangular container having an opening 12h on the upper surface. As shown in Fig. 1, the exterior body 12 includes a bottom wall 12a, a pair of long side walls 12b that extend upward from the long side of the bottom wall 12a and face each other, and a pair of short side walls 12c that extend upward from the short side of the bottom wall 12a and face each other. The bottom wall 12a is substantially rectangular. The bottom wall 12a faces the opening 12h (see Fig. 2). The long side wall 12b and the short side wall 12c are examples of "side walls". The sealing plate 14 is a flat, substantially rectangular plate-like member attached to the exterior body 12 so as to close the opening 12h of the exterior body 12. The sealing plate 14 faces the bottom wall 12a of the exterior body 12. The sealing plate 14 is substantially rectangular. The battery case 10 is integrated by joining (for example, welding) a sealing plate 14 to the periphery of the opening 12h of the exterior body 12. This makes the battery case 10 airtightly sealed (sealed).

[0015] 2, the sealing plate 14 is provided with a liquid injection hole 15, a gas exhaust valve 17, and terminal withdrawal holes 18 and 19. The liquid injection hole 15 is a through hole for injecting an electrolyte into the battery case 10 after the sealing plate 14 is assembled to the exterior body 12. The liquid injection hole 15 is sealed with a sealing member 16 after the electrolyte is injected. The gas exhaust valve 17 is a thin-walled portion configured to break when the pressure inside the battery case 10 reaches or exceeds a predetermined value, thereby discharging gas inside the battery case 10 to the outside.

[0016] The electrolyte may be any electrolyte used in conventional batteries without any particular limitations. An example of the electrolyte is a non-aqueous electrolyte in which a supporting salt is dissolved in a non-aqueous solvent. An example of the non-aqueous solvent is a carbonate-based solvent such as ethylene carbonate, dimethyl carbonate, or ethyl methyl carbonate. An example of the supporting salt is a fluorine-containing lithium salt such as LiPF6. The electrolyte may contain an additive as necessary.

[0017] The positive electrode terminal 30 is attached to one end of the sealing plate 14 in the long side direction Y (the left end in FIG. 1 and FIG. 2). The negative electrode terminal 40 is attached to the other end of the sealing plate 14 in the long side direction Y (the right end in FIG. 1 and FIG. 2). The positive electrode terminal 30 and the negative electrode terminal 40 are inserted through the terminal pull-out holes 18, 19 and 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 and 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 having excellent electrical conductivity, for example, aluminum, an aluminum alloy, copper, a copper alloy, or the like. 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 FIG. 3 and FIG. 4, in the battery 100 of this embodiment, a plurality of (specifically, two) wound electrode bodies 20 are accommodated in the battery case 10. However, the number of wound electrode bodies arranged inside one exterior body 12 is not particularly limited, and may be three or more (multiple), or may be one. The detailed structure of the wound electrode body 20 will be described later, but as shown in FIG. 2, a positive electrode tab group 25 and a negative electrode tab group 27 protrude from the upper part of the wound electrode body 20. The battery 100 has a so-called upper tab structure in which the positive electrode tab group 25 and the negative electrode tab group 27 are located above the wound electrode body 20. As shown in FIG. 4, the positive electrode tab group 25 is curved in a state where it is joined to the positive electrode current collector 50. Although not shown, the negative electrode tab group 27 is similarly curved in a state where it is joined to the negative electrode current collector 60.

[0019] The positive electrode current collecting part 50 electrically connects the positive electrode tab group 25 of the wound electrode body 20 and the positive electrode terminal 30. As shown in FIG. 2, the positive electrode current collecting part 50 is a plate-shaped conductive member extending in the long side direction Y along the inner surface of the sealing plate 14. One end (the right side in FIG. 2) of the positive electrode current collecting part 50 is electrically connected to the positive electrode tab group 25. The other end (the left side in FIG. 2) of the positive electrode current collecting part 50 is electrically connected to the lower end part 30c of the positive electrode terminal 30. The positive electrode terminal 30 and the positive electrode current collecting part 50 are preferably made of a metal having excellent conductivity, for example, aluminum or an aluminum alloy.

[0020] The negative electrode current collecting part 60 electrically connects the negative electrode tab group 27 of the wound electrode body 20 and the negative electrode terminal 40. As shown in FIG. 2, the negative electrode current collecting part 60 is a plate-shaped conductive member extending in the long side direction Y along the inner surface of the sealing plate 14. One end (left side in FIG. 2) of the negative electrode current collecting part 60 is electrically connected to the negative electrode tab group 27. The other end (right side in FIG. 2) of the negative electrode current collecting part 60 is electrically connected to the lower end part 40c of the negative electrode terminal 40. The negative electrode terminal 40 and the negative electrode current collecting part 60 are preferably made of a metal having excellent conductivity, for example, copper or a copper alloy.

[0021] In the battery 100, various insulating members are used to prevent conduction between the wound electrode body 20 and the battery case 10. For example, as shown in FIG. 1, 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 pull-out holes 18 and 19 of the sealing plate 14. This can prevent the positive electrode terminal 30 and the negative electrode terminal 40 inserted into the terminal pull-out holes 18 and 19 from being conducted to the sealing plate 14. Also, 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 side of the sealing plate 14. This can prevent the positive electrode current collector 50 and the negative electrode current collector 60 from being conducted to the sealing plate 14. The internal insulating member 94 may have a protrusion that protrudes toward the wound electrode body 20.

[0022] Furthermore, the multiple wound electrode bodies 20 are arranged inside the exterior body 12 while being covered with an electrode body holder 29 (see FIG. 3) made of an insulating resin sheet. This can prevent the wound electrode body 20 from coming into direct contact with 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).

[0023] 5A is a schematic diagram showing the configuration of the wound electrode body 20. As shown in FIG. 5A, the wound electrode body 20 is configured by stacking a strip-shaped positive electrode 22 and a strip-shaped negative electrode 24 in a state insulated via two strip-shaped separators 70, and winding them in the longitudinal direction around a winding axis WL. The symbol LD in FIG. 5A etc. indicates the longitudinal direction (i.e., the conveying direction) of the wound electrode body 20 and the separator 70 manufactured in a strip shape. The symbol WD is a direction substantially perpendicular to the longitudinal direction LD, and indicates the winding axis direction (also the width direction) of the wound electrode body 20 and the separator 70. The winding axis direction WD is substantially parallel to the up-down direction Z of the battery 100 described above.

[0024] The wound electrode body 20 here has a flat outer shape. The wound electrode body 20 is preferably flat. The flat wound electrode body 20 can be formed, for example, by press-molding an electrode body (cylindrical body) wound into a cylindrical shape into a flat shape. As shown in FIG. 3, the flat wound electrode body 20 has a pair of curved portions 20r whose outer surfaces are curved, and a pair of flat portions 20f whose outer surfaces are flat and connect the pair of curved portions 20r.

[0025] In the battery 100, the wound electrode body 20 is accommodated in the battery case 10 such that the winding axis direction WD is substantially parallel to the long side wall 12b and the short side wall 12c, and is substantially perpendicular to the bottom wall 12a and the sealing plate 14. As shown in FIG. 3, the pair of curved portions 20r face the pair of short side walls 12c of the exterior body 12. The pair of flat portions 20f face the long side walls 12b of the exterior body 12. The end faces of the wound electrode body 20 (i.e., the stacking surfaces where the positive electrode 22 and the negative electrode 24 are stacked, both ends in the winding axis direction WD in FIG. 5A) face the bottom wall 12a and the sealing plate 14.

[0026] As shown in Fig. 5A, the positive electrode 22 is a strip-shaped member. The positive electrode 22 includes a strip-shaped positive electrode collector 22c, and a positive electrode active material layer 22a and a positive electrode protective layer 22p fixed on at least one surface of the positive electrode collector 22c. From the viewpoint of battery performance, the positive electrode active material layer 22a is preferably formed on both sides of the positive electrode collector 22c.

[0027] 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 each member constituting the positive electrode 22. For example, the positive electrode current collector 22c is preferably made of a conductive metal such as aluminum, an aluminum alloy, nickel, or stainless steel, and is a metal foil, specifically an aluminum foil, in this embodiment.

[0028] As shown in FIG. 5A, the positive electrode 22 has a plurality of positive electrode tabs 22t protruding from one end side in the winding axis direction WD toward the outside (upper side in FIG. 5A). The plurality of positive electrode tabs 22t are provided at a predetermined interval (intermittently) along the longitudinal direction LD. The positive electrode tabs 22t are a part of the positive electrode 22 here. The positive electrode tab 22t is a region where the positive electrode active material layer 22a is not formed. A positive electrode protective layer 22p is provided on a part of the positive electrode tab 22t here. However, the positive electrode protective layer 22p may not be provided on the positive electrode tab 22t. The positive electrode current collector 22c is exposed on at least a part of the positive electrode tab 22t. The positive electrode tab 22t may be a member separate from the positive electrode 22.

[0029] Here, each of the positive electrode tabs 22t has a trapezoidal shape. However, the shape of the positive electrode tabs 22t is not limited to this. The size of the positive electrode tabs 22t is also not particularly limited. The shape and size of the positive electrode tabs 22t can be appropriately adjusted depending on the formation position and the like, taking into consideration the state of connection to the positive electrode current collecting part 50, for example. The positive electrode tabs 22t are stacked at one end (the upper end in FIG. 5A) of the positive electrode 22 in the winding axis direction WD, and form a positive electrode tab group 25 (see FIG. 2).

[0030] As shown in FIG. 5A, the positive electrode active material layer 22a is provided in a strip shape along the longitudinal direction LD of the positive electrode current collector 22c. The width of the positive electrode active material layer 22a (length in the winding axis direction WD; the same applies below) is smaller than the width of the negative electrode active material layer 24a. The positive electrode active material layer 22a contains a positive electrode active material capable of reversibly absorbing and releasing charge carriers. The positive electrode active material is preferably a lithium transition metal composite oxide, and more preferably contains Ni. An example of a lithium transition metal composite oxide containing Ni is lithium nickel cobalt manganese composite oxide. The positive electrode active material layer 22a may contain any component other than the positive electrode active material, such as a binder, a conductive material, various additive components, and the like. The positive electrode active material layer 22a preferably contains a binder and a conductive material in addition to the positive electrode active material. The binder is typically made of resin, and fluorine-based resin such as polyvinylidene fluoride (PVdF) is particularly preferable. As the conductive material, a carbon material such as acetylene black (AB) is preferable.

[0031] 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. 5A, the positive electrode protective layer 22p is provided in a strip shape along the longitudinal direction LD of the positive electrode collector 22c. 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 winding axis direction WD. Here, the positive electrode protective layer 22p is provided at one end of the positive electrode collector 22c in the winding axis direction WD, specifically, at the end on the side where the positive electrode tab 22t is located (the upper end of FIG. 5A). By providing the positive electrode protective layer 22p, it is possible to prevent the positive electrode 22 from directly contacting the negative electrode active material layer 24a when the separator 70 is damaged, and the battery 100 from being internally short-circuited.

[0032] The positive electrode protective layer 22p contains an insulating inorganic filler. An example of the inorganic filler is ceramic particles such as alumina. The positive electrode protective layer 22p may contain any component other than the inorganic filler, such as a binder, a conductive material, and various additive components. The binder and the conductive material may be the same as those exemplified as those that may be contained in the positive electrode active material layer 22a. However, the positive electrode protective layer 22p is not essential and may be omitted in other embodiments.

[0033] As shown in Fig. 5A, the negative electrode 24 is a strip-shaped member. The negative electrode 24 includes a strip-shaped negative electrode current collector 24c and a negative electrode active material layer 24a fixed on at least one surface of the negative electrode current collector 24c. From the viewpoint of battery performance, the negative electrode active material layer 24a is preferably formed on both sides of the negative electrode current collector 24c.

[0034] 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 each member constituting the negative electrode 24. 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, and is a metal foil, specifically a copper foil, in this embodiment.

[0035] As shown in FIG. 5A, in the negative electrode 24, a negative electrode tab 24t protrudes from one end side in the winding axis direction WD toward the outside (upper side in FIG. 5A). The negative electrode tabs 24t are provided (intermittently) at a predetermined interval along the longitudinal direction LD. In the winding axis direction WD, the negative electrode tab 24t is provided at the end on the same side as the positive electrode tab 22t. Here, the negative electrode tab 24t is a part of the negative electrode 24. 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, a part of the negative electrode active material layer 24a may protrude and be attached to the negative electrode tab 24t. In addition, the negative electrode tab 24t may be a member separate from the negative electrode 24.

[0036] Here, each of the negative electrode tabs 24t has a trapezoidal shape. However, the shape and size of the negative electrode tabs 24t can be appropriately adjusted, similar to the positive electrode tabs 22t. The negative electrode tabs 24t are stacked at one end (the upper end in FIG. 5A) of the negative electrode 24 in the winding axis direction WD to form a negative electrode tab group 27 (see FIG. 2).

[0037] As shown in FIG. 5A, the negative electrode active material layer 24a is provided in a strip shape along the longitudinal direction LD of the negative electrode current collector 24c. The width of the negative electrode active material layer 24a is larger than the width of the positive electrode active material layer 22a. The width of the negative electrode active material layer 24a refers to the length in the winding axis direction WD of a portion having a substantially constant thickness, and does not include the portion of the negative electrode tab 24t even if a part of the negative electrode active material layer 24a protrudes and adheres to the negative electrode tab 24t. The negative electrode active material layer 24a contains a negative electrode active material capable of reversibly absorbing and releasing charge carriers. The negative electrode active material is preferably, for example, a carbon material such as graphite or a silicon material. The negative electrode active material layer 24a may contain any component other than the negative electrode active material, such as a binder, a conductive material, various additive components, and the like. The negative electrode active material layer 24a preferably contains a binder in addition to the negative electrode active material. The binder preferably contains rubbers such as styrene butadiene rubber (SBR) and celluloses such as carboxymethyl cellulose (CMC). The negative electrode active material layer 24a may contain a carbon material as a conductive material as necessary.

[0038] As shown in FIG. 5A and FIG. 11, the separator 70 is a strip-shaped member. The separator 70 is an insulating sheet having a plurality of fine through-holes through which charge carriers can pass. The width of the separator 70 is greater than the width of the negative electrode active material layer 24a. By interposing the separator 70 between the positive electrode 22 and the negative electrode 24, contact between the positive electrode 22 and the negative electrode 24 can be prevented, and charge carriers (e.g., lithium ions) can be moved between the positive electrode 22 and the negative electrode 24. Although not particularly limited, the thickness of the separator 70 (length in the stacking direction MD; the same applies below) is preferably 3 μm or more, more preferably 5 μm or more. The thickness of the separator 70 is preferably 25 μm or less, more preferably 18 μm or less, and even more preferably 14 μm or less.

[0039] Here, two separators 70 are used for one wound electrode body 20. As in this embodiment, it is preferable that two separators 70, that is, a first separator and a second separator, are included for one wound electrode body 20. Also, here, the two separators have different configurations, but they may have the same configuration.

[0040] As the substrate layer 72, a microporous film used in a separator of a conventionally known battery can be used without any particular limitation. The substrate layer 72 is preferably a porous sheet-like member. The substrate layer 72 may have a single-layer structure or a structure of two or more layers, for example a three-layer structure. At least the surface of the substrate layer 72 facing the negative electrode 24 is preferably made of a polyolefin resin. It is more preferable that the substrate layer 72 is entirely made of a polyolefin resin. This ensures sufficient flexibility of the separator 70, and makes it easy to manufacture the wound electrode body 20 (winding and press molding). As the polyolefin resin, polyethylene (PE), polypropylene (PP), or a mixture thereof is preferable, and it is more preferable that the substrate layer 72 is made of PE.

[0041] Although not particularly limited, the thickness of the base layer 72 (length in the stacking direction MD; the same applies below) is preferably 3 μm or more, and more preferably 5 μm or more. The thickness of the base layer 72 is preferably 25 μm or less, more preferably 18 μm or less, and even more preferably 14 μm or less. The air permeability of the base layer 72 is preferably 30 sec / 100 cc to 500 sec / 100 cc, more preferably 30 sec / 100 cc to 300 sec / 100 cc, and even more preferably 50 sec / 100 cc to 200 sec / 100 cc. The base layer 72 may have an adhesiveness to such an extent that it can be bonded to the negative electrode active material layer 24a by, for example, heating or press molding.

[0042] The heat-resistant layer 73 is provided on the substrate layer 72. The heat-resistant layer 73 is preferably formed on the substrate layer 72. The heat-resistant layer 73 may be provided directly on the surface of the substrate layer 72, or may be provided on the substrate layer 72 via another layer. However, the heat-resistant layer 73 is not essential and may be omitted in other embodiments. The heat-resistant layer 73 is provided on the entire surface of the substrate layer 72 facing the positive electrode 22. This can more accurately suppress the thermal contraction of the separator 70 and contribute to improving the safety of the battery 100. The heat-resistant layer 73 does not have enough adhesiveness to be bonded to the positive electrode active material layer 22a by, for example, heating or press molding. The basis weight of the heat-resistant layer 73 is uniform in the longitudinal direction LD and the winding axis direction WD of the separator 70. Although not particularly limited, the thickness of the heat-resistant layer 73 (length in the stacking direction MD; the same applies below) is preferably 0.3 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more. The thickness of the heat-resistant layer 73 is preferably equal to or less than 6 μm, and more preferably equal to or less than 4 μm. The heat-resistant layer 73 preferably contains an inorganic filler and a heat-resistant layer binder.

[0043] As the inorganic filler, any inorganic filler that has been publicly known and used for this type of application can be used without any particular limitation. The inorganic filler preferably contains insulating ceramic particles. Among them, in consideration of heat resistance, availability, and the like, inorganic oxides such as alumina, zirconia, silica, titania, metal hydroxides such as aluminum hydroxide, and clay minerals such as boehmite are preferred, and alumina and boehmite are more preferred. In addition, from the viewpoint of suppressing thermal contraction of the separator 70, compounds containing aluminum are particularly preferred. The ratio of the inorganic filler to the total mass of the heat-resistant layer 73 is preferably 85 mass% or more, more preferably 90 mass% or more, and even more preferably 95 mass% or more.

[0044] The heat-resistant layer binder may be any binder that has been conventionally used for this type of application 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.

[0045] The adhesive layer 74 is provided on a surface facing the positive electrode 22 and is in contact with the positive electrode 22. As shown in FIG. 11, the adhesive layer 74 is preferably formed at least on the surface of the separator 70 on the positive electrode 22 side. This allows the above-mentioned effects to be more effectively exhibited. The adhesive layer 74 is bonded to the positive electrode 22 by, for example, heating or pressing (typically, press molding). Although not particularly limited, the thickness of the adhesive layer 74 (length in the stacking direction MD; the same applies below) is preferably 0.3 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more. The thickness of the adhesive layer 74 is preferably 6 μm or less, and more preferably 4 μm or less.

[0046] The adhesive layer 74 is provided on the heat-resistant layer 73 here. The adhesive layer 74 is preferably formed on the heat-resistant layer 73. The adhesive layer 74 may be provided directly on the surface of the heat-resistant layer 73, or may be provided on the heat-resistant layer 73 via another layer. The adhesive layer 74 may be provided directly on the surface of the base layer 72, or may be provided on the base layer 72 via a layer other than the heat-resistant layer 73. The configuration of the adhesive layer 74 is not particularly limited and may be the same as that of a conventionally known layer. The adhesive layer 74 may be a layer that has a relatively high affinity with the electrolyte compared to, for example, the heat-resistant layer 73, and swells by absorbing the electrolyte. The adhesive layer 74 contains an adhesive layer binder.

[0047] As the adhesive layer binder, a conventionally known resin material having a certain viscosity with respect to the positive electrode 22 can be used without any particular limitation. Specific examples include acrylic resins, fluorine resins, epoxy resins, urethane resins, ethylene vinyl acetate resins, polyallylamine (PAA) resins, cellulose resins such as carboxymethyl cellulose (CMC), and the like. Among them, fluorine resins and acrylic resins are preferred because they have high flexibility and can more suitably exhibit adhesiveness to the positive electrode 22. Examples of fluorine resins include polyvinylidene fluoride (PVdF) and polytetrafluoroethylene (PTFE). The type of the adhesive layer binder may be the same as or different from the heat-resistant layer binder. The ratio of the heat-resistant layer binder to the total mass of the adhesive layer 74 is preferably 20% by mass or more, more preferably 50% by mass or more, and even more preferably 70% by mass or more. This allows the separator 70 to accurately exhibit a predetermined adhesiveness to the positive electrode 22 and to be easily deformed during press molding.

[0048] The adhesive layer 74 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 74 contains an inorganic filler, the proportion of the inorganic filler to the total mass of the adhesive layer 74 is preferably 80 mass % or less, more preferably 50 mass % or less, and even more preferably 30 mass % or less.

[0049] Next, the configuration of the wound electrode body 20 will be described with reference to the drawings as appropriate. Here, Figs. 6A to 6C are schematic longitudinal sectional views taken along the line VI-VI in Fig. 5B. Fig. 7 is an enlarged view of the area enclosed by the dashed line in Fig. 6A. Fig. 8 is an enlarged view of the area enclosed by the dashed line in Fig. 6A. Fig. 9 is an enlarged view of the area enclosed by the solid line in Fig. 6A. In the following description, the adhesive layer formed on the first separator 70A is referred to as the first adhesive layer, and the adhesive layer formed on the second separator 70B is referred to as the second adhesive layer. The first adhesive layer 74a includes a region facing the positive electrode 22. Of the second adhesive layers, the second adhesive layer including a region facing the positive electrode 22 is referred to as the second adhesive layer 74b1, and the second adhesive layer formed on the inner surface of the extension 28 is referred to as the second adhesive layer 74b2.

[0050] As shown in FIG. 6A, the wound electrode body 20 includes a first separator 70A and a second separator 70B as separators. The second separator 70B has a region located outside the winding end end 70a2 of the first separator. As shown in FIG. 6A and FIG. 7, the second separator 70B has an extension 28 that extends beyond the winding end end 70a2 of the first separator in the winding direction D1, and a second adhesive layer 74b2 is formed on at least a part of the inner surface of the extension 28. The extension 28 and a region S of the second separator 70B located inside the extension 28 are bonded by the second adhesive layer 74b2. According to this configuration, even if a stop tape is not used in the manufacture of the wound electrode body 20, the winding end end of the separator (here, the winding end end 70b2 of the second separator) can be suitably fixed to the wound body. This makes it possible to omit a mechanism for applying a stop tape that can complicate the configuration of the electrode body manufacturing apparatus, and therefore the wound electrode body 20 can be easily obtained by the electrode body manufacturing apparatus.

[0051] As shown in FIG. 6B, in this embodiment, the wound electrode body 20 has a second separator 70B on the outermost surface, which does not face the positive electrode 22. Here, the length of the extension portion 28 in the winding direction D1 is, for example, 10% or more when the length of the outermost circumference of the wound electrode body 20 (corresponding to P in FIG. 6B) is taken as 100%, and from the viewpoint of suitably fixing the extension portion 28 to the wound body, it is preferably 15% or more, and more preferably 20% or more. In addition, the upper limit of the length of the extension portion 28 in the winding direction D1 is, for example, 40% or less of the length of the outermost circumference of the wound electrode body 20, and from the viewpoint of reducing costs, etc., it is preferably 30% or less. However, it is not limited to these.

[0052] As shown in FIG. 6C, when the length of the second separator between V and W in the winding direction D1 is 360°, the end of the extension portion 28 (i.e., the winding end 70b2 of the second separator) is located at, for example, 370° or more (e.g., 372° or more) from the point V, and may be located at a position of 390° or more, or may be located at a position of 400° or more (e.g., 405° or more). In addition, the end of the extension portion 28 is located at, for example, 720° or less from the point V, and may be located at a position of 700° or less. However, this is not limited to these. Note that the points V and W indicate positions of the second separator 70B corresponding to the winding end 24T of the negative electrode.

[0053] The length of the extension portion 28 in the winding direction D1 is, for example, 250 mm or more, and from the viewpoint of suitably fixing the extension portion 28 to the winding body, it is preferably 300 mm or more (for example, 310 mm or more or 350 mm or more), more preferably 400 mm or more (for example, 410 mm or more), and even more preferably 450 mm or more (for example, 460 mm or more). The upper limit of the length of the extension portion 28 in the winding direction D1 is, for example, 700 mm or less, and from the viewpoint of reducing costs, etc., it is preferably 600 mm or less, and more preferably 500 mm or less. However, it is not limited to these.

[0054] The area of ​​the second adhesive layer 74b2 formed on the extension portion 28 is, for example, 10% or more when the area corresponding to the extension portion 28 on the surface of the second separator 70B on the side in contact with the positive electrode 22 (corresponding to 70B1 in FIG. 5A and FIG. 9) is taken as 100%, and from the viewpoint of suitably improving the adhesion between the extension portion 28 and the region S located on the inside of the extension portion 28 in the second separator 70B, it may be preferably 20% or more, for example 30% or more, or 40% or more. In addition, the area of ​​the second adhesive layer 74b2 formed on the extension portion 28 may be 100% (i.e., a mode in which the second adhesive layer 74b2 is formed on the entire surface of the extension portion 28, corresponding to this embodiment), or from the viewpoint of reducing costs, it may be preferably 90% or less, for example 80% or less, 70% or less, 60% or less, or 50% or less.

[0055] In this embodiment, in the second separator 70B, the basis weight of the second adhesive layer 74b2 on the inner surface of the extension portion 28 is greater than the basis weight of the second adhesive layer 74b1 in the region facing the positive electrode 22. This configuration is preferable because it can suitably improve the adhesion between the extension portion 28 and the region S of the second separator 70B that is located more inward than the extension portion 28. In this specification and claims, the term "basis weight" refers to the value obtained by dividing the mass of the adhesive layer by the area of ​​the formation region (mass of the adhesive layer / area of ​​the formation region).

[0056] Here, in the second separator 70B, when the basis weight of the second adhesive layer 74b2 on the inner surface of the extension portion 28 is X and the basis weight of the second adhesive layer 74b1 in the region facing the positive electrode 22 is Y, the value of the ratio (X / Y) is not particularly limited as long as the effect of the technology disclosed herein is exhibited. On the other hand, from the viewpoint of suitably improving the adhesion between the extension portion 28 and the region S located on the inner side of the extension portion 28 in the second separator 70B, the ratio is preferably 1.1 or more, and may be, for example, 1.2 or more, 1.3 or more. In addition, from the viewpoint of reducing costs, the upper limit of the ratio (X / Y) is preferably 2.0 or less, and may be, for example, 1.8 or less, 1.5 or less. Note that in other embodiments, the value of the ratio (X / Y) may be less than 1 or may be 1. The same applies to the second adhesive layers 174b1 and 174b2, 374b1 and 374b2 described later.

[0057] Although not particularly limited, the basis weight of the second adhesive layer 74b1 in the region facing the positive electrode 22 is, for example, 0.005 g / m 2 or more, preferably 0.01 g / m 2 More preferably, it is 0.02 g / m or more. 2 The upper limit of the basis weight of the second adhesive layer 74b1 is, for example, 2.0 g / m 2 or less, preferably 1.0 g / m 2 More preferably, it is 0.05 g / m or less. 2 The following is the result.

[0058] Although not particularly limited, the basis weight of the second adhesive layer 74b2 on the inner surface of the extension portion 28 is, for example, 0.005 g / m 2 or more, preferably 0.01 g / m 2 More preferably, it is 0.02 g / m or more. 2 The upper limit of the basis weight of the second adhesive layer 74b2 is, for example, 2.0 g / m 2 or less, preferably 1.0 g / m 2 More preferably, it is 0.05 g / m or less. 2 The following is the result.

[0059] As shown in FIG. 8, in this embodiment, the second separator 70B has a second adhesive layer 74b1 formed in a region facing the positive electrode 22, and the second separator 70B and the positive electrode 22 are bonded by the second adhesive layer 74b1. In addition, the first separator 70A has a first adhesive layer 74a formed in a region facing the positive electrode 22, and the first separator 70A and the positive electrode 22 are bonded by the first adhesive layer 74a. Here, the force that the wound electrode body 20 tries to restore from a flat shape to a cylindrical shape (so-called springback) is said to be mainly caused by the expansion of the positive electrode 22 based on the charge and discharge of the battery 100. As in this embodiment, by fixing the positive electrode 22 by the first adhesive layer 74a and the second adhesive layer 74b1, the expansion of the positive electrode 22 can be suppressed, and thus the springback can be suitably suppressed.

[0060] As shown in FIG. 8, in this embodiment, the first adhesive layer is not formed in the region of the first separator 70A facing the negative electrode 24, and the second adhesive layer is not formed in the region of the second separator 70B facing the negative electrode 24. As described above, when the expansion of the positive electrode 22 is suppressed by the first adhesive layer 74a and the second adhesive layer 74b1, it is not necessary to form an adhesive layer in the region facing the negative electrode 24 (or, even if an adhesive layer is formed, its formation area may be small). According to this configuration, the amount of the adhesive layer to be applied can be reduced, which is preferable from the viewpoint of reducing costs, etc. In addition, by reducing the amount of the adhesive layer, the thickness of the wound electrode body 20 can be suitably reduced and the absorption of the electrolyte can be suitably suppressed.

[0061] Here, when the area of ​​the surface of the second separator 70B that contacts the negative electrode 24 (corresponding to 70B2 in Figures 5A and 9) is taken as 100%, the area of ​​the second adhesive layer (or the first adhesive layer) in the region of the second separator 70B that faces the negative electrode 24 (or the region of the first separator 70A that faces the negative electrode 24) is, for example, 50% or less, and from the standpoint of reducing costs, reducing the thickness of the wound electrode body 20, suppressing absorption of the electrolyte, etc., it is preferably 40% or less, 30% or less, and may be, for example, 20% or less, 10% or less, 5% or less (0% in this embodiment).

[0062] As shown in FIG. 9, in this embodiment, the first adhesive layer is not formed in the winding start region of the first separator 70A on the surface of the first separator 70A that contacts the positive electrode 22 (corresponding to 70A1 in FIG. 5A and FIG. 9). Also, 70A2 in FIG. 5A and FIG. 9 shows the surface of the first separator 70A that contacts the negative electrode 24. According to this configuration, the amount of adhesive layer to be applied can be reduced, which is preferable from the viewpoint of reducing costs, etc. Also, by reducing the amount of adhesive layer, the thickness of the wound electrode body 20 can be suitably reduced and the absorption of the electrolyte can be suitably suppressed. In this specification and claims, the "winding start region of the first separator" may mean, for example, a region of the first separator 70A from the winding start end 70a1 to one turn (corresponding to the region between C and D in FIG. 9), preferably a region to two turns.

[0063] In another embodiment, a first adhesive layer may be formed in the winding start region of the first separator 70A on the surface of the side of the first separator 70A that contacts the positive electrode 22. In such a case, the basis weight of the first adhesive layer in the winding start region of the first separator is preferably smaller than the basis weight of the first adhesive layer 74a in the region facing the positive electrode 22. Here, when the basis weight of the first adhesive layer 74a in the region facing the positive electrode 22 is taken as 100%, the basis weight of the first adhesive layer in the winding start region of the first separator is, for example, 50% or less, and from the viewpoints of reducing costs, reducing the thickness of the wound electrode body 20, suppressing absorption of the electrolyte, and the like, it is preferably 40% or less, 30% or less, and may be, for example, 20% or less, 10% or less.

[0064] As shown in FIG. 9, in this embodiment, the second adhesive layer is not formed in the winding start region of the second separator 70B on the surface of the side of the second separator 70B that contacts the positive electrode 22 (corresponding to 70B1 in FIG. 5A and FIG. 9). With this configuration, the amount of adhesive layer to be applied can be reduced, which is preferable from the viewpoint of cost reduction and the like. Furthermore, by reducing the amount of adhesive layer, the thickness of the wound electrode body 20 can be suitably reduced and the absorption of the electrolyte can be suitably suppressed. In this specification and claims, the "winding start region of the second separator" may mean, for example, a region of the second separator 70B from the winding start end 70b1 of the second separator to one turn (corresponding to the region between EF in FIG. 9), preferably a region to two turns.

[0065] In another embodiment, a second adhesive layer may be formed in the winding start region of the second separator 70B on the surface of the side of the second separator 70B that contacts the positive electrode 22. In such a case, the basis weight of the second adhesive layer in the winding start region of the second separator is preferably smaller than the basis weight of the second adhesive layer 74b1 in the region facing the positive electrode 22. Here, when the basis weight of the second adhesive layer 74b1 in the region facing the positive electrode 22 is taken as 100%, the basis weight of the second adhesive layer in the winding start region of the second separator is, for example, 50% or less, and from the viewpoints of reducing costs, reducing the thickness of the wound electrode body 20, suppressing absorption of the electrolyte, and the like, it is preferably 40% or less, 30% or less, and may be, for example, 20% or less, 10% or less.

[0066] As shown in FIG. 6B, in this embodiment, a second adhesive layer is not formed on the outer surface of the second separator located on the outermost surface of the wound electrode body 20 (see P in FIG. 6B). With this configuration, the amount of adhesive layer to be applied can be reduced, which is preferable from the viewpoint of reducing costs, etc. Also, it is preferable from the viewpoint of ease of handling the wound electrode body 20. Furthermore, by reducing the amount of adhesive layer, the thickness of the wound electrode body 20 can be suitably reduced, and absorption of the electrolyte can be suitably suppressed.

[0067] In another embodiment, a second adhesive layer may be formed on the outer surface of the second separator 70B located on the outermost surface of the wound electrode body 20. In this case, the basis weight of the second adhesive layer on such an outer surface is preferably smaller than the basis weight of the second adhesive layer 74b1 in the region facing the positive electrode 22. Here, when the basis weight of the second adhesive layer 74b1 in the region facing the positive electrode 22 is taken as 100%, the basis weight of the second adhesive layer on the outermost surface of the second separator 70B located on the outermost surface of the wound electrode body 20 can be approximately 50% or less, and from the viewpoints of reducing costs, reducing the thickness of the wound electrode body 20, suppressing absorption of the electrolyte, etc., it is preferably 40% or less, 30% or less, and may be, for example, 20% or less, 10% or less.

[0068] As shown in FIG. 6B, in this embodiment, the second adhesive layer is not formed on the outer surface of the second separator 70B located on the outermost surface of the wound electrode assembly 20 (see P in FIG. 6B). That is, the area of ​​the second adhesive layer on the outer surface of the second separator 70B located on the outermost surface of the wound electrode assembly 20 is 30% or less of the area of ​​the outer surface. With this configuration, the amount of adhesive layer to be applied can be reduced, which is preferable from the viewpoint of reducing costs, etc. Also, when the area of ​​the adhesive layer on the outermost surface of the wound electrode assembly 20 is small, it is preferable from the viewpoint of ease of handling. Note that the area of ​​the second adhesive layer on the outer surface of the second separator 70B located on the outermost surface of the wound electrode assembly 20 may be 20% or less, 10% or less (0% in this embodiment) of the area of ​​the outer surface.

[0069] In this embodiment, the basis weight of the second adhesive layer in the entire second separator 70B is greater than the basis weight of the first adhesive layer in the entire first separator 70A. Specifically, the basis weight of the second adhesive layer in the entire second separator 70B is greater because the basis weight of the second adhesive layer 74b2 is greater. This configuration makes it possible to optimize the total amount of adhesive layers (in other words, to prevent excessive adhesive layers from being formed), which is preferable because it realizes the following: suppressing the thickness of the wound electrode body 20, improving the impregnation of the electrolyte, suppressing absorption of the electrolyte, etc. In addition, when two types of second adhesive layers (i.e., second adhesive layer 74b1 and second adhesive layer 74b2) with different basis weights are formed, as in the second separator 70B of this embodiment, the basis weight of the second adhesive layers of the entire second separator 70B refers to the sum of the masses of second adhesive layer 74b1 and second adhesive layer 74b2 divided by the sum of the areas of the formation regions of second adhesive layer 74b1 and second adhesive layer 74b2 {(mass of second adhesive layer 74b1 + mass of second adhesive layer 74b2) / (area of ​​the formation region of second adhesive layer 74b1 + area of ​​the formation region of second adhesive layer 74b2)}.

[0070] Here, when the basis weight of the adhesive layer 74 of the entire second separator 70B is M and the basis weight of the adhesive layer 74 of the entire first separator 70A is N, the value of the ratio (M / N) is not particularly limited as long as the effects of the technology disclosed herein are exhibited. On the other hand, from the viewpoint of preferably obtaining the effects as described above, the ratio is preferably 1.1 or more, more preferably 1.2 or more, and may be, for example, 1.3 or more. Furthermore, the upper limit of the ratio (M / N) is, for example, 2.0 or less, and may be 1.8 or less, or 1.5 or less.

[0071] 6A, in this embodiment, the first separator 70A and the second separator 70B are bonded to each other on the winding start side of the winding start end 22S of the positive electrode 22 in the winding direction D1, without the positive electrode 22 therebetween. Also, the first separator 70A and the second separator 70B are bonded to each other on the winding end side of the winding end end 22T of the positive electrode 22 in the winding direction D1, without the positive electrode 22 therebetween. Note that 24S in FIG. 6A indicates the winding start end of the negative electrode 24.

[0072] As shown in Fig. 6A, in this embodiment, in the second separator 70B, there is a region where the second adhesive layer 74b1 is not formed in the region facing the positive electrode 22 and the region between the extensions 28 (the region corresponding to the region between G and H in Fig. 6A). With this configuration, the amount of adhesive layer to be applied can be reduced, which is preferable from the viewpoint of reducing costs, etc. Furthermore, by reducing the adhesive layer, the thickness of the wound electrode body 20 can be suitably reduced, and absorption of the electrolyte can be suitably suppressed.

[0073] As shown in FIG. 6A, in this embodiment, the difference in winding direction D1 between the winding start end 70a1 of the first separator and the winding start end 70b1 of the second separator is smaller than the difference in winding direction D1 between the winding end end 70a2 of the first separator and the winding end end 70b2 of the second separator.

[0074] Although not particularly limited, when the length of second separator 70B in the longitudinal direction (LD direction in FIG. 5A) is Q and the length of first separator 70A in the longitudinal direction is R, the value of the ratio (Q / R) is, for example, 1.1 or more, and may be 1.2 or more, or 1.3 or more. The upper limit of the ratio (Q / R) is, for example, 1.5 or less, and may be 1.4 or less.

[0075] In this embodiment, the first separator 70A has a region where the first adhesive layer is not formed in the rolling start region and the rolling end region of the first separator 70A. The second separator 70B has a region where the second adhesive layer is not formed in the rolling start region and the rolling end region of the second separator 70B. In this specification and claims, the "rolling end region of the first separator" may mean, for example, the region that is the outermost surface of the first separator 70A (the region corresponding to the IJ region in FIG. 6C). In addition, the "rolling end region of the second separator" may mean, for example, the region that is the outermost surface of the second separator 70B (the region corresponding to the KL region in FIG. 6C).

[0076] As shown in FIG. 6A, in this embodiment, the winding end 22T of the positive electrode is located at one of the pair of curved portions 20r, and the winding end 24T of the negative electrode is located at one of the pair of curved portions 20r. With this configuration, it is possible to suppress the generation of a convex portion in the flat portion 22f of the wound electrode body 20. This makes it possible to prevent localized stress (especially when used in a battery pack), and therefore to suitably suppress reaction unevenness and the like. In this embodiment, the winding end 24T of the negative electrode extends further in the winding direction D1 than the winding end 22T of the positive electrode. In addition, as in this embodiment, it is preferable that the winding end 22T of the positive electrode is disposed on one side in the winding direction D1 with respect to the center line L1, and the winding end 24T of the negative electrode is disposed on the other side in the winding direction D1. The winding end of the separator (here, the winding end 70b2 of the second separator) may be located on either the flat portion 20f or the curved portion 20r of the wound electrode body 20, but it is preferable that it is located on the flat portion 20f of the wound electrode body 20, as in this embodiment, because winding can be more reliably stopped.

[0077] As shown in FIG. 6A, in this embodiment, a stop tape (a member for fixing the end of the separator to the winding body) is not applied to the end 70b2 of the second separator. Here, for example, if a stop tape is used, the electrolyte tends to be absorbed by the glue contained in the stop tape, which is considered to be undesirable from the viewpoint of battery performance. In addition, with regard to the thickness of the winding body, it is considered to be undesirable because a convex part is generated at the part where the stop tape is applied, which may cause reaction unevenness. On the other hand, as in the wound electrode body 20 according to this embodiment, if the end of the winding is a separator with a small thickness (here, the second separator 70B) and further, no stop tape is applied, it is preferable because the above-mentioned problems can be solved. Furthermore, in a battery 100 in which a plurality of wound electrode bodies 20 are housed in a battery case 10 as in this embodiment, each wound electrode body 20 has a winding end, so that the above-mentioned effects are particularly easy to obtain.

[0078] The internal insulating member 94 has a protrusion that protrudes from the inner surface of the sealing plate 14 toward the wound electrode body 20. This restricts movement of the wound electrode body 20 in the vertical direction Z. Therefore, even if the wound electrode body 20 is subjected to an impact such as vibration or dropping, it becomes difficult for the wound electrode body 20 to interfere with the sealing plate 14, and damage to the wound electrode body 20 can be suppressed.

[0079] <Battery manufacturing method> Next, a method for manufacturing the battery 100 will be described. Note that the battery 100 disclosed herein is characterized by the method for manufacturing the wound electrode body 20, and other steps related to the method for manufacturing the battery can be performed according to conventionally known methods. Therefore, only the method for manufacturing the wound electrode body 20 will be described below.

[0080] FIG. 10 is a schematic diagram showing the configuration of the first separator and the second separator. FIG. 11 is an explanatory diagram for explaining the manufacturing method of the wound electrode body. As shown in FIG. 11, in the manufacturing of the wound electrode body 20, first, the first separator 70A, the positive electrode 22, the second separator 70B, and the negative electrode 24 are prepared. Here, the first adhesive layer 74a, the second adhesive layer 74b1, and the second adhesive layer 74b2 are preferably formed in a dot-like, striped, wavy, band-like (striped), dashed line-like, or a combination thereof in a plan view. This can improve the impregnation of the electrolyte into the inside of the wound electrode body 20. In this specification, "the formation region is formed in a linear shape" means that the formation region is linear, and the adhesive layer itself may be in a dot-like shape, etc.

[0081] Next, each member is wound by the winding roller 200. Thereafter, the wound body is pressed with a predetermined pressure to obtain the wound electrode body 20. As described above, in the technique of the present disclosure, the second adhesive layer 74b2 is formed on at least a part of the inner surface of the extension portion 28, so that the winding end end of the separator (here, the winding end end 70b2 of the second separator) can be suitably fixed to the wound body. This makes it possible to easily obtain the wound electrode body 20 without complicating the configuration of the electrode body manufacturing apparatus.

[0082] <Battery uses> Battery 100 can be used for various purposes, but can be suitably used, for example, as a power source (driving power source) for a motor mounted on a vehicle such as a passenger car or truck. The type of vehicle is not particularly limited, but examples include a plug-in hybrid electric vehicle (PHEV), a hybrid electric vehicle (HEV), and a battery electric vehicle (BEV). Battery 100 has reduced variation in battery reaction, and can therefore be suitably used to construct a battery pack.

[0083] 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 technical common sense in the field. The technology described in the claims includes various modifications and changes to the above-exemplified embodiments. For example, it is possible to replace a part of the above-mentioned embodiment with another modified form, and it is also possible to add another modified form to the above-mentioned embodiment. Furthermore, if a technical feature is not described as essential, it is also possible to delete it as appropriate.

[0084] For example, in the above embodiment, the wound electrode body 20 has a configuration in which multiple positive electrode tabs 22t and multiple negative electrode tabs 24t protrude outward from one end edge in the winding axis direction WD, but is not limited to this. The technology disclosed here can also be applied to a wound electrode body in which, for example, multiple positive electrode tabs 22t protrude outward from one end edge in the winding axis direction WD and multiple negative electrode tabs 24t protrude outward from the other end edge in the winding axis direction WD. The technology disclosed here can also be applied to a wound electrode body in which the positive electrode tabs 22t and the negative electrode tabs 24t are not formed.

[0085] For example, in the above embodiment, the winding end end 70b2 of the second separator is not provided with a winding stop tape, but the present invention is not limited to this. For example, the winding end end 70b2 of the second separator may be provided with a winding stop tape. The winding stop tape can be provided by manual work or the like after the wound body is produced by an electrode body manufacturing device. Note that as the winding stop tape, any conventionally known tape used for this type of battery can be used without any particular limitation.

[0086] For example, in the above embodiment, the winding end 22T of the positive electrode and the winding end 24T of the negative electrode are located in the curved portion 22r of the wound electrode body 20, but this is not limited thereto. For example, the winding end 24T of the positive electrode may be located in the curved portion 20r of the wound electrode body 20, and the winding end 24T of the negative electrode may be located in the flat portion 20f of the wound electrode body 20. This configuration is preferable because it is possible to suppress the generation of a convex portion in the flat portion 22f of the wound electrode body 20 and the shape of the curved portion 20r is stable.

[0087] FIG. 12 is a schematic diagram showing the configuration of the first separator 170A and the second separator 170B according to the second embodiment. In the second embodiment, the second adhesive layer 174b2 is formed in a state in which it is divided into a plurality of rectangular regions (three regions in this case). The basis weight of the second adhesive layer 174b2 is greater than the basis weight of the second adhesive layer 174b1. The shape of the second adhesive layer 174b2 in a plan view is not particularly limited as long as the effect of the technology disclosed herein is exhibited, and may be, for example, a circular shape, an elliptical shape, or various other shapes. The first adhesive layer 174a is formed on the first separator 170A. It is preferable that the formation regions of the first adhesive layer and the second adhesive layer are the minimum necessary from the viewpoint of ensuring the wettability of the electrolyte.

[0088] 13 is a schematic diagram showing the configuration of a first separator 270A and a second separator 270B according to the third embodiment. In the third embodiment, in the first separator 270A, a first adhesive layer 274a is formed from a winding start end 270a1 of the first separator to a winding end end 270a2 of the first separator. In addition, in the second separator 270B, a second adhesive layer 274b is formed from a winding start end 270b1 of the second separator to a winding end end 270b2 of the second separator.

[0089] 14 is a schematic diagram showing the configuration of a first separator 370A and a second separator 370B according to the fourth embodiment. In the fourth embodiment, a first adhesive layer 374a is formed in the first separator 370A from a winding start end 370a1 to a winding end end 370a2 of the first separator. In addition, a second adhesive layer 374b1 and a second adhesive layer 374b2 are formed in the second separator 370B. The basis weight of the second adhesive layer 374b2 is larger than the basis weight of the second adhesive layer 374b1.

[0090] 15 is a schematic diagram showing the configuration of a first separator 470A and a second separator 470B according to the fifth embodiment. In the fifth embodiment, a first adhesive layer 474a is formed in a region of the first separator 470A other than the winding start region and the winding end region. Also, a second adhesive layer 474b is formed in a region of the second separator 470B other than the winding start region.

[0091] 12 to 15 correspond to 72 in FIG. 10, and 173, 273, 373, and 473 correspond to 73 in FIG.

[0092] As described above, specific aspects of the technology disclosed herein include those described in the following items. Item 1: A battery including a wound electrode body in which a strip-shaped positive electrode and a strip-shaped negative electrode are wound in a predetermined winding direction around a winding axis, with a strip-shaped separator interposed therebetween, the battery including a first separator and a second separator as the separators, the second separator having a region located outside the winding end end of the first separator, the second separator having an extension portion that extends beyond the winding end end of the first separator in the winding direction, a second adhesive layer being formed on at least a part of the inner surface of the extension portion, and the extension portion and a region of the second separator located inside the extension portion being bonded by the second adhesive layer. Item 2: The battery according to item 1, wherein the extension portion is not provided with a winding stop tape. Item 3: The battery according to item 1 or 2, wherein the second separator has a second adhesive layer formed in a region facing the positive electrode, and the second separator and the positive electrode are bonded by the second adhesive layer, and the first separator has a first adhesive layer formed in a region facing the positive electrode, and the first separator and the positive electrode are bonded by the first adhesive layer. Item 4: The battery according to any one of Items 1 to 3, wherein the second adhesive layer is not formed on an outer surface of the second separator located on the outermost surface of the wound electrode body, or the second adhesive layer is formed on the outer surface, and when the second adhesive layer is formed, the basis weight of the second adhesive layer on the outer surface is smaller than the basis weight of the second adhesive layer in a region facing the positive electrode. Item 5: The battery according to any one of items 1 to 4, wherein the area of ​​the second adhesive layer on the outer surface of the second separator located on the outermost surface of the wound electrode body is 30% or less of the area of ​​the outer surface. Item 6: The battery according to any one of items 1 to 5, wherein the second adhesive layer is not formed in a winding start region of the second separator on a surface of the second separator that contacts the positive electrode, or the second adhesive layer is formed therein, and if the second adhesive layer is formed, the basis weight of the second adhesive layer in the winding start region of the second separator is smaller than the basis weight of the second adhesive layer in a region facing the positive electrode. Item 7: The battery according to any one of items 1 to 6, wherein a first adhesive layer is not formed in a winding start region of the first separator on a surface of the first separator that contacts the positive electrode, or the first adhesive layer is formed, and if the first adhesive layer is formed, the basis weight of the first adhesive layer in the winding start region of the first separator is smaller than the basis weight of the first adhesive layer in a region facing the positive electrode. Item 8: The battery according to any one of items 1 to 7, wherein the wound electrode body is formed in a flat shape and has a pair of curved portions with curved outer surfaces and a flat portion with a flat outer surface that connects the pair of curved portions, a winding end end of the positive electrode is located at one of the pair of curved portions, and a winding end end of the negative electrode is located at one of the pair of curved portions. [Explanation of symbols]

[0093] 10 Battery case 12 Exterior body 12a Bottom wall 12b long side wall 12c short side wall 12h opening 14 Sealing plate 15 Liquid injection hole 16 Sealing member 17 Gas exhaust valve 18 Terminal extraction hole 20 Wound electrode body 20f flat area 20r curved section 22 Positive electrode 22a Cathode active material layer 22c Positive electrode current collector 22p positive electrode protective layer 22t Positive electrode tab 24 Negative electrode 24a Negative electrode active material layer 24c Negative electrode current collector 24t negative electrode tab 25 Positive electrode tab group 27 Negative electrode tab group 29 Electrode holder 30 Positive terminal 30c bottom end 32 Positive electrode external conductive member 34 Heat-resistant layer 40 Negative terminal 40c bottom end 42 Negative electrode external conductive member 50 Positive electrode current collector 60 Negative electrode current collector 70 Separator 70A, 170A, 270A, 370A, 470A First separator 70B, 170B, 270B, 370B, 470B Second separator 72,172,272,372,472 Base material layer 73,173,273,373,473 Heat resistant layer 74 Adhesive layer 74a,174a,274a,374a,474a 1st adhesive layer 74b1,74b2,174b1,174b2,274b,374b1,374b2,474b 2nd adhesive layer 90 Gasket 92 External insulating material 94 Internal insulation material 100 batteries 200 Winding roller LD Longitudinal U upward WL winding shaft Y Longitudinal direction Z vertical direction

Claims

1. A battery including a wound electrode body in which a strip-shaped positive electrode and a strip-shaped negative electrode are wound in a predetermined winding direction around a winding axis with a strip-shaped separator interposed therebetween, The positive electrode includes a positive electrode active material layer, The separator includes a first separator and a second separator, the second separator has a region located outside a winding end of the first separator, the second separator has an extension portion that extends beyond a winding end portion of the first separator in the winding direction, a second adhesive layer is formed on at least a portion of the inner surface of the extension portion; the second adhesive layer is formed in a region of the second separator facing the positive electrode active material layer, and the second separator and the positive electrode active material layer are bonded to each other by the second adhesive layer; the extension portion and a region of the second separator located on the inner side of the extension portion are bonded to each other by the second adhesive layer, The second adhesive layer is formed in a divided state on the second separator, a region in which the second adhesive layer is not provided is formed between a region in the second separator that is bonded to the positive electrode active material layer by the second adhesive layer and a region in the second separator that is bonded to a region located more inward than the extended portion by the second adhesive layer, in a longitudinal direction of the second separator; The battery, wherein the extension portion is not provided with a winding stop tape.

2. A battery comprising a wound electrode body in which a strip-shaped positive electrode and a strip-shaped negative electrode are wound in a predetermined winding direction around a winding axis via a strip-shaped separator, The positive electrode includes a positive electrode active material layer, The separator includes a first separator and a second separator, the second separator has a region located outside a winding end of the first separator, the second separator has an extension portion that extends beyond a winding end portion of the first separator in the winding direction, a second adhesive layer is formed on at least a portion of the inner surface of the extension portion; the second adhesive layer is formed in a region of the second separator facing the positive electrode active material layer, and the second separator and the positive electrode active material layer are bonded to each other by the second adhesive layer; the extension portion and a region of the second separator located on the inner side of the extension portion are bonded to each other by the second adhesive layer, a weight per unit area of ​​the second adhesive layer in a region bonded to a region located on the inner side of the extension portion is greater than a weight per unit area of ​​the second adhesive layer in a region bonded to the positive electrode active material layer, The battery, wherein the extension portion is not provided with a winding stop tape.

3. A battery as described in claim 1 or 2, wherein a first adhesive layer is formed in the area of ​​the first separator facing the positive electrode, and the first separator and the positive electrode are adhered by the first adhesive layer.

4. The outer surface of the second separator located on the outermost surface of the wound electrode body has The second adhesive layer is not formed or the second adhesive layer is formed, 3 . The battery according to claim 1 , wherein when the second adhesive layer is formed, a basis weight of the second adhesive layer on the outer surface is smaller than a basis weight of the second adhesive layer in a region facing the positive electrode.

5. 3 . The battery according to claim 1 , wherein an area of ​​the second adhesive layer on an outer surface of the second separator located on the outermost surface of the wound electrode body is 30% or less of an area of ​​the outer surface.

6. On a surface of the second separator that contacts the positive electrode, The second separator has a winding start region, The second adhesive layer is not formed or the second adhesive layer is formed, 3. The battery according to claim 1, wherein when the second adhesive layer is formed, a basis weight of the second adhesive layer in a winding start region of the second separator is smaller than a basis weight of the second adhesive layer in a region facing the positive electrode.

7. On a surface of the first separator that contacts the positive electrode, The winding start region of the first separator includes: The first adhesive layer is not formed or the first adhesive layer is formed, 3. The battery according to claim 1, wherein when the first adhesive layer is formed, a basis weight of the first adhesive layer in a winding start region of the first separator is smaller than a basis weight of the first adhesive layer in a region facing the positive electrode.

8. The wound electrode body is formed in a flat shape, A pair of curved portions having curved outer surfaces, and a flat portion having a flat outer surface connecting the pair of curved portions, a winding end portion of the positive electrode is located at one of the pair of curved portions, 3. The battery according to claim 1, wherein a winding end of the negative electrode is located at one of the pair of curved portions.

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