Battery

Abstract

To provide a battery capable of favorably combining the formability of a wound electrode body and the liquid injection performance.SOLUTION: A battery comprises a wound electrode body configured by winding a belt-like positive electrode with a positive electrode active material layer and a belt-like negative electrode with a negative electrode active material layer via a belt-like separator 70. The separator 70 has an adhesive layer at least on one surface. The adhesive layer is formed to change the coating weight of the adhesive layer in a longitudinal direction LD of the separator 70.SELECTED DRAWING: Figure 7

Description

[Technical field]

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

[0002] Conventionally, there is known a battery having a wound electrode body in which a strip-shaped positive electrode having a positive electrode active material layer and a strip-shaped negative electrode 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 wound electrode body in which an adhesive is applied to the entire surface of the separator to integrate the separator with at least one of the positive electrode and the negative electrode. [Prior art documents] [Patent documents]

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

[0004] However, according to the results of the studies by the present inventors, when an adhesive is applied to the entire surface of the separator, it becomes difficult for the electrolyte to penetrate into the wound electrode body, and there is a risk that the electrolyte injection property of the wound electrode body may be reduced. On the other hand, when an adhesive is not applied to the separator, there is a risk that the formability of the wound electrode body may be reduced. The present invention has been made in view of such points, and has an object to provide a battery in which the formability and electrolyte injection property of the wound electrode body are favorably compatible. [Means for solving the problem]

[0005] The battery disclosed herein includes a wound electrode body in which a strip-shaped positive electrode having a positive electrode active material layer and a strip-shaped negative electrode having a negative electrode active material layer are wound with a strip-shaped separator interposed therebetween. The separator has an adhesive layer on at least one surface. The adhesive layer is formed so that the basis weight of the adhesive layer changes in the longitudinal direction of the separator.

[0006] By providing an adhesive layer with a predetermined basis weight on the separator, the shape of the wound electrode body can be sufficiently maintained, and the moldability of the wound electrode body can be improved. Moreover, in the above configuration, excessive formation of the adhesive layer on the separator is suppressed, and the liquid injectability of the wound electrode body is sufficiently ensured. Therefore, a battery in which the moldability and liquid injectability of the wound electrode body are favorably compatible is realized. In this specification, the term "basis weight of adhesive layer (g / m2)" refers to the 2 ) is the area (m 2 ) is the mass of the adhesive layer (g) [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view showing a schematic diagram of a battery according to an embodiment. [Diagram 2] FIG. 2 is a schematic vertical cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 3 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. [Diagram 5] FIG. 5 is a schematic diagram showing the configuration of the wound electrode body according to the first embodiment. [Figure 6] FIG. 6 is a diagram showing a schematic configuration of the separator. [Figure 7] FIG. 7 is a plan view that illustrates an example of the surface of a separator. [Figure 8] FIG. 8 is a diagram showing a schematic example of the positions at which the first formation region and the second formation region are formed in the wound electrode body. [Figure 9] FIG. 9 is a plan view diagrammatically illustrating another example of the surface of the separator. [Figure 10] FIG. 10 is a plan view that illustrates another example of the surface of the separator. [Figure 11]FIG. 11 is a diagram showing a schematic diagram of another example of the positions at which the first formation region and the second formation region are formed in the wound electrode body. [Figure 12] FIG. 12 is a plan view that illustrates another example of the surface of the separator. [Figure 13] FIG. 13 is an enlarged view that illustrates a schematic diagram of the interface between the positive electrode, the negative electrode, and the separator. [Figure 14] FIG. 14 is a view of the battery according to the second embodiment, corresponding to FIG. [Figure 15] FIG. 15 is a diagram corresponding to FIG. 8 and diagrammatically illustrates an example of the positions at which the first formation region and the second formation region are formed in the wound electrode body according to the second embodiment. [Figure 16] FIG. 16 is a view of a separator according to a first modified example, which corresponds to FIG. [Figure 17] FIG. 17 is a view of a separator according to a second modified example, which corresponds to FIG. [Figure 18] FIG. 18 is a view of a separator according to a third modified example, which corresponds to FIG. [Figure 19] FIG. 19 is a diagram for explaining the formation angle of the second formation region according to the third modified example. [Figure 20] FIG. 20 is a view of a separator according to a fourth modified example, which corresponds to FIG. [Figure 21] FIG. 21 is a diagram for explaining the formation angle of the second formation region according to the fourth modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, the embodiments of the technology disclosed herein will be described with reference to the drawings. Note 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 do not characterize the technology disclosed herein) can be understood as design matters of a person skilled in the art based on the conventional technology in the field. The technology disclosed herein can be implemented based on the contents disclosed in this specification and the technical common sense in the field. Note 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".

[0009] In this specification, the term "battery" refers to any power 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 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 includes 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] First Embodiment FIG. 1 is a perspective view of a battery 100. The battery 100 is preferably a secondary battery, and more preferably 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", the symbol Y indicates the "long side direction of the battery", and the symbol Z indicates the "up-down direction of the battery". However, these are merely directions for convenience of description, and do not limit the installation form of the battery 100 in any way.

[0011] As shown in Fig. 1 and Fig. 2, the battery 100 includes a battery case 10, a plurality of wound electrode bodies 20, a positive electrode terminal 30, a negative electrode terminal 40, a positive electrode current collector 50, and a negative electrode current collector 60. Although not shown, the battery 100 further includes an electrolyte. The battery 100 is a non-aqueous electrolyte secondary battery. The specific configuration of the battery 100 will be described below.

[0012] The battery case 10 is a housing that houses the wound electrode body 20. Here, the battery case 10 has an external shape of a rectangular parallelepiped (square) with a bottom. 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 closes the opening 12h. The exterior body 12 and the sealing plate 14 have sizes according to the number of wound electrode bodies 20 housed (one or more; here, more than one), the size, and the like.

[0013] As shown in FIG. 1, the exterior body 12 includes a bottom wall 12a, a pair of long side walls 12b extending from the bottom wall 12a and facing each other, and a pair of short side walls 12c extending from the bottom wall 12a and facing each other. The bottom wall 12a is substantially rectangular. The bottom wall 12a faces an opening 12h (see FIG. 2). The sealing plate 14 is 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 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).

[0014] 2, the sealing plate 14 is provided with a liquid injection hole 15, a gas exhaust valve 17, and two terminal extraction 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.

[0015] The battery case 10 may house an electrolyte together with the wound electrode body 20 as described above. As the electrolyte, any electrolyte used in conventionally known batteries may be used without any particular limitation. As an example, a non-aqueous electrolyte in which a supporting salt is dissolved in a non-aqueous solvent may be used. As an example of the non-aqueous solvent, a carbonate-based solvent such as ethylene carbonate, dimethyl carbonate, or ethyl methyl carbonate may be used. As an example of the supporting salt, a fluorine-containing lithium salt such as LiPF6 may be used.

[0016] 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.

[0017] 3 and 4, the battery 100 here has a plurality (two) of wound electrode bodies 20 housed in a battery case 10. A detailed structure of the wound electrode body 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 FIG. 2). These electrode tab groups (positive electrode tab group 25 and negative electrode tab group 27) are connected in a curved state to the electrode current collectors (positive electrode current collector 50 and negative electrode current collector 60).

[0018] 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 side of the sealing plate 14. One side (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. In addition, the other side (right side in FIG. 2) of the positive electrode current collecting part 50 is electrically connected to the positive electrode tab group 25. The positive electrode terminal 30 and the positive electrode current collecting part 50 are preferably made of a metal having 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.

[0019] 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 side of the sealing plate 14. One side (the 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. In addition, the other side (the left side in FIG. 2) of the negative electrode current collecting part 60 is electrically connected to the negative electrode tab group 27. The negative electrode terminal 40 and the negative electrode current collecting part 60 are preferably made of a metal having 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.

[0020] In the battery 100, various insulating members are attached 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, 19 of the sealing plate 14. This can prevent the positive electrode terminal 30 (or the negative electrode terminal 40) inserted into the terminal pull-out holes 18, 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. Note that, as shown in the second embodiment described later, the internal insulating member 94 may have a protruding portion protruding toward the wound electrode body 20.

[0021] 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. 2) made of an insulating resin sheet. This can prevent 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] Here, two wound electrode bodies 20 are housed in the exterior body 12. 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. In addition, as shown in Fig. 3, the wound electrode body 20 has a pair of curved portions 20r that face the short side wall 12c of the exterior body 12, and a flat portion 20f that connects the pair of curved portions 20r and faces the long side wall 12b of the exterior body 12.

[0023] FIG. 5 is a schematic diagram showing the configuration of the wound electrode body 20. As shown in FIG. 5, 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 of being insulated via two strip-shaped separators 70, 71, and winding them in the longitudinal direction around the winding axis WL. The symbol LD in FIG. 5 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 longitudinal direction LD is a direction that coincides with the long side direction Y of the above-mentioned battery 100. The symbol TD is a direction perpendicular to the longitudinal direction LD and indicates the width direction of the wound electrode body 20 and the separator 70. The width direction TD is a direction that coincides with the up-down direction Z of the above-mentioned battery 100. In the following description, the left side of the longitudinal direction LD in FIG. 5 etc. is the winding start side of the wound electrode body 20, and the right side is the winding end side of the wound electrode body 20.

[0024] The wound electrode body 20 is disposed inside the exterior body 12 with the winding axis WL (see FIG. 5) oriented parallel to the up-down direction Z of the exterior body 12. In other words, the wound electrode body 20 is disposed inside the exterior body 12 with the winding axis WL oriented parallel to the short side wall 12c and perpendicular to the bottom wall 12a. An end face of the wound electrode body 20 (in other words, the layered surface where the positive electrode 22 and the negative electrode 24 are layered, the end face in the width direction TD in FIG. 5) faces the bottom wall 12a and the sealing plate 14.

[0025] As shown in FIG. 5, the positive electrode 22 is a strip-shaped member. The positive electrode 22 has 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. However, the positive electrode protective layer 22p is not essential and can be omitted in other embodiments. For each member constituting the positive electrode 22, a conventionally known material that can be used in a general battery (e.g., a lithium ion secondary battery) can be used without any particular restriction. 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.

[0026] As shown in FIG. 5, in the positive electrode 22, a plurality of positive electrode tabs 22t protrude from one end side in the width direction TD of the wound electrode body 20 toward the outside (upper side in FIG. 5). The plurality of positive electrode tabs 22t are provided (intermittently) at a predetermined interval along the longitudinal direction LD. The positive electrode tabs 22t are connected to the positive electrode 22. Here, the positive electrode tab 22t is a part of the positive electrode collector 22c, and is made of a 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 collector 22c is exposed. However, the positive electrode tab 22t may be provided with the positive electrode active material layer 22a and / or the positive electrode protective layer 22p in a part thereof, and may be a member different from the positive electrode collector 22c. Here, each of the plurality of positive electrode tabs 22t is trapezoidal. However, the shape of the positive electrode tab 22t is not limited thereto. The size of the plurality of positive electrode tabs 22t is also not particularly limited. The shape and size of the positive electrode tab 22t can be appropriately adjusted by its formation position, etc., taking into consideration, for example, the state of connection to the positive electrode current collecting part 50. The multiple positive electrode tabs 22t are stacked at one end (the upper end in FIG. 5) in the width direction TD of the positive electrode 22 to form a positive electrode tab group 25 (see FIG. 2).

[0027] As shown in FIG. 5, the positive electrode active material layer 22a is provided in a strip shape along the longitudinal direction LD of the strip-shaped positive electrode current collector 22c. The positive electrode active material layer 22a contains a positive electrode active material (for example, a lithium transition metal composite oxide such as a lithium nickel cobalt manganese composite oxide) capable of reversibly absorbing and releasing charge carriers. When the entire solid content of the positive electrode active material layer 22a is taken as 100 mass%, the positive electrode active material may occupy approximately 80 mass% or more, typically 90 mass% or more, for example 95 mass% or more. The positive electrode active material layer 22a may contain any component 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] 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. 5, the positive electrode protective layer 22p is provided in a strip shape along the longitudinal direction LD of the strip-shaped positive electrode collector 22c. As shown in FIG. 5, 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 width direction TD. Here, the positive electrode protective layer 22p is provided at one end (the upper end in FIG. 5) of the positive electrode collector 22c in the width direction TD. However, the positive electrode protective layer 22p may be provided at both ends in the width direction TD. By providing the positive electrode protective layer 22p, it is possible to prevent the positive electrode collector 22c and the negative electrode active material layer 24a from coming into direct contact with each other when the separators 70 and 71 are damaged, and thus prevent the battery 100 from being internally short-circuited.

[0029] The positive electrode protective layer 22p contains an insulating inorganic filler, for example, ceramic particles such as alumina. When the entire solid content of the positive electrode protective layer 22p is taken as 100 mass%, the inorganic filler may occupy approximately 50 mass% or more, typically 70 mass% or more, for example 80 mass% or more. The positive electrode protective layer 22p may contain any component other than the inorganic filler, for example, a conductive material, a binder, various additive components, and the like. The conductive material and the binder may be the same as those exemplified as those that may be contained in the positive electrode active material layer 22a.

[0030] The negative electrode 24 is a strip-shaped member as shown in FIG. 5. The negative electrode 24 has 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. For each member constituting the negative electrode 24, a 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.

[0031] As shown in FIG. 5, in the negative electrode 24, a negative electrode tab 24t protrudes from one end side in the width direction TD of the wound electrode body 20 toward the outside (upper side in FIG. 5). The multiple negative electrode tabs 24t are provided (intermittently) at a predetermined interval along the longitudinal direction LD. The negative electrode tab 24t is connected to the negative electrode 24. Here, the negative electrode tab 24t is a part of the negative electrode collector 24c, and is made of a 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 collector 24c is exposed. However, the negative electrode tab 24t may have the negative electrode active material layer 24a formed in a part thereof, and may be a member different from the negative electrode 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 appropriately adjusted in the same manner as the positive electrode tab 22t. The negative electrode tabs 24t are stacked at one end of the negative electrode 24 in the width direction TD (the upper end in FIG. 5) to form a negative electrode tab group 27 (see FIG. 2).

[0032] The negative electrode active material layer 24a is provided in a strip shape along the longitudinal direction LD of the strip-shaped negative electrode current collector 24c. The negative electrode active material layer 24a contains a negative electrode active material (for example, a carbon material such as graphite) that can reversibly store and release charge carriers. The width of the negative electrode active material layer 24a (the length in the width direction TD; the same applies below) is preferably larger than the width of the positive electrode active material layer 22a. When the entire solid content of the negative electrode active material layer 24a is taken as 100 mass%, the negative electrode active material may occupy approximately 80 mass% or more, typically 90 mass% or more, for example 95 mass% or more. The negative electrode active material layer 24a may contain any component other than the negative electrode active material, such as a conductive material, a binder, a dispersant, various additive components, etc. An example of the binder is a rubber such as styrene butadiene rubber (SBR). An example of the dispersant is a cellulose such as carboxymethyl cellulose (CMC).

[0033] The separators 70 and 71 are strip-shaped members. The separators 70 and 71 are insulating sheets having a plurality of fine through-holes through which charge carriers can pass. The width of the separators 70 and 71 is greater than the width of the negative electrode active material layer 24a. By interposing the separators 70 and 71 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.

[0034] As shown in FIG. 6, the separators 70 and 71 have an adhesive layer 74 formed on at least one surface. It is sufficient that the adhesive layer 74 is formed on at least one of the separators 70 and 71. Preferably, the adhesive layer 74 is formed on both the separators 70 and 71. The separators 70 and 71 typically have a base layer 72 made of a porous resin and an adhesive layer 74 having an adhesive component. As shown in FIG. 6, the separators 70 and 71 further have a heat-resistant layer 73 between the base layer 72 and the adhesive layer 74.

[0035] As the substrate layer 72, a microporous film used in a separator of a conventionally known battery can be used without any particular restriction. 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. The substrate layer 72 is preferably made of a polyolefin resin. This ensures sufficient flexibility of the separator 70, and facilitates the production of the wound electrode body 20 (winding and press molding). As the polyolefin resin, polyethylene (PE), polypropylene (PP), or a mixture thereof is preferable, and PE is more preferable.

[0036] Although not particularly limited, the thickness t1 of the base layer 72 is preferably 3 μm or more and 25 μm or less, more preferably 3 μm or more and 18 μm or less, and even more preferably 5 μm or more and 14 μm or less. Although not particularly limited, the air permeability of the base layer 72 is preferably 30 sec / 100 cc or more and 500 sec / 100 cc or less, more preferably 30 sec / 100 cc or more and 300 sec / 100 cc or less, and even more preferably 50 sec / 100 cc or more and 200 sec / 100 cc or less. Furthermore, although not particularly limited, the porosity of the base layer 72 may be, for example, 20% or more and 70% or less, or 30% or more and 60% or less. The porosity of the base layer 72 can be measured by mercury intrusion porosimetry.

[0037] The heat-resistant layer 73 is provided on the base layer 72. The heat-resistant layer 73 may be provided directly on the surface of the base layer 72, or may be provided on the base layer 72 via another layer. However, the heat-resistant layer 73 is not essential and may be omitted in other embodiments. The basis weight of the heat-resistant layer 73 is uniform in the longitudinal direction LD and the width direction TD of the separator 70. Although not particularly limited, the thickness t2 of the heat-resistant layer 73 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. The heat-resistant layer 73 preferably contains an inorganic filler and a heat-resistant layer binder.

[0038] 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 preferable, and alumina and boehmite are more preferable. In addition, from the viewpoint of suppressing thermal shrinkage of the separator 70, compounds containing aluminum are particularly preferable. 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. By making the content of the inorganic particles a predetermined amount or more, the thermal shrinkage of the base layer 72 is suppressed.

[0039] 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.

[0040] As shown in FIG. 6, the adhesive layer 74 is formed on one surface of the separator 70. However, the adhesive layer 74 may be formed on both surfaces of the separator 70. The adhesive layer 74 may be provided on the outermost surface of the separators 70 and 71. The adhesive layer 74 may be provided directly on the surface of the base layer 72, for example. Alternatively, a heat-resistant layer 73 may be provided on the surface of the base layer 72, and the adhesive layer 74 may be provided on the surface of the heat-resistant layer 73. Alternatively, the adhesive layer 74 may be provided on the base layer 72 via any other layer. It is preferable that the heat-resistant layer 73 is provided on one or both sides of the base layer 72, and the adhesive layer 74 is provided on the surface of the heat-resistant layer 73.

[0041] The thickness t3 of the adhesive layer 74 may vary depending on the basis weight described below, but is preferably approximately 0.3 μm to 6 μm, more preferably 0.5 μm to 6 μm, and even more preferably 1 μm to 4 μm.

[0042] The adhesive layer 74 is bonded to the electrodes (positive and / or negative electrodes) by, for example, heating or pressing (typically, press molding). The adhesive layer 74 includes an adhesive layer binder. 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, and ethylene vinyl acetate resins. 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 mass% or more, more preferably 50 mass% or more, and even more preferably 70 mass% or more. This allows the separator 70 to exhibit a predetermined adhesiveness to the positive electrode 22 and makes the separator 70 more easily deformable during press molding.

[0043] 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.

[0044] The separator 70 of the battery 100 disclosed herein has an adhesive layer 74 on at least one surface, and the basis weight (g / m 2) is formed so as to vary. In the wound electrode body 20, a phenomenon in which the flat portion 20f expands due to the elastic action remaining in the curved portion 20r (hereinafter referred to as "springback") is likely to occur. In the longitudinal direction LD of the separator 70, the adhesive layer 74 is provided so as to vary its basis weight, so that, for example, the above-mentioned springback can be suitably suppressed. This improves the formability of the wound electrode body 20. On the other hand, if the adhesive layer 74 is provided excessively on the surface of the separator 70, there is a risk that the electrolyte will be absorbed by the adhesive layer 74 and the electrolyte injection property will decrease. For this reason, from the viewpoint of electrolyte injection property, it is preferable that the adhesive layer 74 is not provided excessively on the surface of the separator 70. From these viewpoints, by appropriately adjusting the position where the adhesive layer 74 is formed in the longitudinal direction LD of the separators 70 and 71, it is possible to suitably suppress the springback of the wound electrode body 20 while suppressing the decrease in electrolyte injection property.

[0045] In the following, the configuration of the separator disclosed herein will be described using separator 70 as an example, but the same configuration may be used for separator 71. As described above, at least one of separators 70 and 71 may have the configuration described below.

[0046] The separator 70 of the battery 100 disclosed herein has an adhesive layer 74 formed on at least one surface. According to the findings of the present inventors, it has been found that when the positive electrode 22 and the separator 70 are bonded together, they tend to peel off slightly more easily than when the negative electrode 24 and the separator 70 are bonded together. Therefore, from this viewpoint, it is preferable that the adhesive layer 74 is formed at least on the surface on the side that contacts the positive electrode 22. This improves the adhesion between the positive electrode 22 and the separator 70 of the wound electrode body 20, and improves the formability of the wound electrode body 20. On the other hand, the adhesiveness between the negative electrode 24 and the separator 70 is relatively high, and even if the adhesive layer 74 is not formed on the side that contacts the negative electrode 24, the formability of the wound electrode body 20 can be sufficiently ensured. In addition, if the adhesive layer 74 is formed excessively as described above, there is a risk that the liquid injection property will decrease. Therefore, from these viewpoints, it is preferable that the base material layer 72 of the separator 70 contacts the negative electrode 24.

[0047] The adhesive layer 74 may be applied in a solid manner or in a predetermined pattern. For example, the adhesive layer 74 may be formed in a dotted, striped, wavy, band (striped), broken line, or a combination thereof in a plan view. The basis weight of the adhesive layer 74 described above can be controlled, for example, by changing the application pattern of the adhesive layer 74. As an example, the area with a relatively large basis weight may be applied entirely (solidly), and the area with a relatively small basis weight may be applied partially. Alternatively, the basis weight of the adhesive layer 74 can be controlled by changing the application amount even if the application pattern is the same. As an example, the adhesive layer 74 in the area with a relatively large basis weight and the area with a relatively small basis weight may both be applied in a dotted manner, and the adhesive layer 74 in the area with a relatively small basis weight may be applied in a smaller amount than the adhesive layer 74 in the area with a relatively large basis weight.

[0048] 7 is a plan view showing the surface of the separator 70 before forming the wound electrode body 20. The separator 70 of the battery 100 disclosed herein has a basis weight (g / m 2) is changed. The adhesive layer 74 is appropriately arranged at a position where springback can be suitably suppressed as described above. For example, as shown in FIG. 7, the separator 70 has a first forming region 81 on which the adhesive layer 74 is formed and a second forming region 82 on which the adhesive layer 74 is formed on its surface, and it is preferable that the basis weight of the adhesive layer 74 in the first forming region 81 is smaller than the basis weight of the adhesive layer 74 in the second forming region 82. It is preferable that the first forming region 81 and the second forming region 82 are repeatedly formed in the longitudinal direction LD of the separator 70. According to this configuration, the second forming region 82 in which the basis weight of the adhesive layer 74 is relatively large suitably suppresses springback, improving the formability of the wound electrode body 20. In addition, in the first forming region 81 in which the basis weight of the adhesive layer 74 is relatively small, the electrolyte is easily permeated, improving the pourability. Furthermore, the adhesive layer 74, which can be a resistance component of the battery 100, is reduced in amount compared to conventional cases, thereby improving the battery performance of the battery 100.

[0049] The coating weight A (g / m 2 ) is the basis weight B (g / m 2 ) of the adhesive layer 74 in the second forming region 82 2 ) of the adhesive layer 74 in the second forming region 82. 2 ) of the adhesive layer 74 in the first forming region 81 relative to the surface area A (g / m 2 The ratio (A / B) of the fiber length (A) and the fiber width (B) is preferably 0.1 or more and 0.9 or less, may be 0.2 or more and 0.75 or less, and more preferably 0.3 or more and 0.5 or less. Although not particularly limited, the basis weights of the first forming region 81 and the second forming region 82 are each 0.005 to 1.0 g / m 2 is preferable, and 0.02 to 0.04 g / m 2 is more preferred.

[0050] The basis weights of the first formation region 81 and the second formation region 82 described above can be controlled, for example, by changing the application pattern of the adhesive layer 74. As an example, the first formation region 81 may be formed by applying the adhesive layer 74 in a dot pattern, and the second formation region 82 may be formed by applying the adhesive layer 74 over the entire surface. Alternatively, the basis weights of the first formation region 81 and the second formation region 82 can be controlled by changing the application amount even if the application pattern is the same. As an example, it is preferable that the adhesive layer 74 of both the first formation region 81 and the second formation region 82 are applied in a dot pattern, and the adhesive layer 74 of the first formation region 81 is applied in a smaller amount than the adhesive layer 74 of the second formation region 82.

[0051] 8 and 11 are diagrams showing an example of the positions of the first forming region 81 and the second forming region 82 in the flat wound electrode body 20. The symbol MD in FIG. 8 and other figures indicates the stacking direction of the wound electrode body 20, which is the same direction as the short side direction X of the battery 100 described above. The wound electrode body 20 is flat, and preferably includes a flat portion 20f and a curved portion 20r. The first forming region 81 is preferably located in the flat portion 20f, and the second forming region 82 is preferably located in the curved portion 20r. This improves the permeability of the electrolyte in the flat portion 20f. In addition, the second forming region 82, which has a relatively large basis weight, is located in the curved portion 20r, so that the inter-electrode distance in the curved portion 20r is stabilized, and the battery resistance can be reduced. The flat wound electrode body refers to a wound electrode body that is substantially oval in cross section and has a so-called racetrack shape (see FIG. 3). Such a flat wound electrode body 20 can be formed, for example, by press-molding a cylindrically wound electrode body into a flat shape.

[0052] The first forming region 81 may be provided in at least a part of the flat portion 20f, and may be provided in the entire flat portion 20f. The second forming region 82 may be provided in at least a part of the curved portion 20r, and may be provided in the entire curved portion 20r. In addition, the boundary 20b between the curved portion 20r and the flat portion 20f of the wound electrode body 20 and the boundary 81b between the first forming region 81 and the second forming region 82 may not coincide with each other. That is, as shown in FIG. 8, a part of the second forming region 82 may be provided in the flat portion 20f. Alternatively, a part of the first forming region 81 may be provided in the curved portion 20r.

[0053] In a preferred embodiment, as shown in Fig. 8, the second forming region 82 is provided at the boundary 20b between the curved portion 20r and the flat portion 20f, and is provided so as to abut against a part of the end of the flat portion 20f. The length L1 of the second forming region 82 in the longitudinal direction LD is preferably slightly longer than the length La of the curved portion 20r of the wound electrode body 20. For example, the length L1 of the second forming region 82 is preferably 5% or more longer than the length La of the curved portion 20r, and may be 10% or more longer. On the other hand, the length L1 of the second forming region 82 is preferably 150% or less of the length La of the curved portion 20r, and may be 125% or less.

[0054] On the other hand, from the viewpoint of suitably suppressing springback, it is preferable that the first forming region 81 is located in the curved portion 20r, and the second forming region 82 is located in the flat portion 20f in the wound electrode body 20. As described above, springback is a phenomenon in which the flat portion 20f expands due to the elastic action remaining in the curved portion 20r of the wound electrode body 20. Therefore, by arranging the second forming region 82, in which the basis weight of the adhesive layer 74 is relatively large, in the flat portion 20f, springback can be suitably suppressed. In addition, by arranging the first forming region 81, in which the basis weight of the adhesive layer 74 is relatively small, in the curved portion 20r, the liquid injectability in the curved portion 20r can be sufficiently ensured. Therefore, according to this configuration, the formability and liquid injectability of the wound electrode body 20 can be compatible. In this case, the first forming region 81 may be provided in at least a part of the curved portion 20r, and may be provided in the entire curved portion 20r. The second forming region 82 may be provided in at least a part of the flat portion 20f, and may be provided in the entire flat portion 20f. As described above, the boundary 20b between the curved portion 20r and the flat portion 20f of the wound electrode body 20 and the boundary 81b between the first forming region 81 and the second forming region 82 may not coincide with each other. That is, a part of the first forming region 81 may be provided in the flat portion 20f. Alternatively, a part of the second forming region 82 may be provided in the curved portion 20r.

[0055] 9 and 10 are plan views showing an example of the surface of the separator 70 before the winding electrode body 20 is constructed. In the separator 70, it is preferable that the length of each of the first forming regions 81 changes in the longitudinal direction LD of the separator 70. Alternatively, it is preferable that the length of each of the second forming regions 82 changes in the longitudinal direction LD of the separator 70. It is preferable that the lengths of the first forming region 81 and the second forming region 82 are formed so that at least one of them changes. The lengths of the first forming region 81 and the second forming region 82 may be formed so that both of them change. For example, as shown in FIG. 9, the separator 70 may be formed so that the first forming region 81 and the second forming region 82 are repeatedly formed in the longitudinal direction LD, and the length of the second forming region 82 is longer in accordance with the length of the curved portion 20r when the winding electrode body 20 is constructed. Although not shown, the separator 70 may be formed such that the first forming region 81 and the second forming region 82 are repeatedly formed in the longitudinal direction LD, and the length of the first forming region 81 is long in accordance with the length of the curved portion 20r when the wound electrode body 20 is constructed. By adjusting the length of the first forming region 81 and / or the second forming region 82 in accordance with the length of the curved portion 20r when the wound electrode body 20 is constructed as described above, the first forming region 81 and the second forming region 82 can be arranged at a desired position of the wound electrode body 20. Although not particularly limited, from the viewpoint of formability of the wound electrode body 20, it is preferable that the length of the second forming region 82 is long in the longitudinal direction LD of the separator 70 so that the second forming region 82 is located at the curved portion 20r of the wound electrode body 20.

[0056] As shown in FIG. 11, in a preferred embodiment, the separator 70 has a first forming region 81 and a second forming region 82 repeatedly formed in the longitudinal direction LD, the first forming region 81 being disposed in a part of the flat portion 20f and a part of the curved portion 20r, and the second forming region 82 being disposed in a boundary vicinity region including the boundary 20b between the curved portion 20r and the flat portion 20f. Here, the boundary vicinity region is a region including the boundary 20b between the curved portion 20r and the flat portion 20f, and including a part of the flat portion 20f and a part of the curved portion 20r. The boundary 20b and the boundary vicinity region are particularly susceptible to stress when the wound electrode body 20 is constructed. For this reason, by disposing the second forming region 82, which has a relatively large basis weight, in such a position, the formability of the wound electrode body 20 can be more suitably improved. In addition, the liquid injection property of the wound electrode body 20 can be further improved compared to providing the second forming region 82 in the entire curved portion 20r.

[0057] FIG. 12 is a plan view showing an example of the surface of the separator 70 before forming the wound electrode body 20. The separator 70 preferably further has a third forming region 83 in addition to the above-mentioned first forming region 81 and second forming region 82. The third forming region 83 is formed on the end side of the separator 70 in the width direction TD from the first forming region 81. The third forming region 83 may be formed on the upper end side (U direction in FIG. 12) or on the lower end side (D direction in FIG. 12) of the separator 70 in the width direction TD. As shown in FIG. 12, the third forming region 83 has an adhesive layer 74 formed along the longitudinal direction LD of the separator 70. By providing the third forming region 83, which is on the end side from the first forming region 81 in the width direction TD of the separator 70 in this way, the electrode and the separator 70 are suitably bonded at the end of the width direction TD of the wound electrode body 20, and the intrusion of foreign matter can be prevented. It is also possible to improve resistance to the separator 70 being turned over and resistance to vibration during use of the battery 100. This makes it possible to provide a battery 100 of higher quality.

[0058] Moreover, it is preferable that the separator 70 further has a fourth formation region 84 at an end portion in the width direction TD of the separator 70 where the third formation region 83 is not formed. The fourth formation region 84 is a region where the adhesive layer 74 is formed along the longitudinal direction LD of the separator 70. This allows the electrodes and the separator 70 to be more suitably bonded at the end portion in the width direction TD of the wound electrode body 20, and makes it possible to prevent, for example, the separator 70 from curling up. 12, the region located on the upper end side in the width direction TD is the third forming region 83, and the region located on the lower end side in the width direction TD is the fourth forming region 84, but these are merely directions for convenience of explanation and do not limit the form of the battery 100 disclosed herein. For example, only the third forming region 83 may be formed on the lower end side of the separator 70 in the width direction TD.

[0059] In the separator 70 of the battery 100 disclosed herein, the basis weight of the adhesive layer 74 in the third formation region 83 and the fourth formation region 84 is greater than the basis weight of the adhesive layer 74 in the first formation region 81. For example, the basis weight C (g / m 2 ) of the adhesive layer 74 in the first forming region 81 relative to the surface area A (g / m 2 The ratio (A / C) of the surface area ratio (A / C) is preferably 0.1 or more and 0.9 or less, may be 0.2 or more and 0.75 or less, and more preferably 0.3 or more and 0.5 or less. 2 ) of the adhesive layer 74 in the first forming region 81 relative to the surface area A (g / m 2 The ratio (A / D) of the total surface area (A) and the total surface area (D) is preferably 0.1 to 0.9, may be 0.2 to 0.75, and more preferably 0.3 to 0.5. Although not particularly limited, the basis weights of the third forming region 83 and the fourth forming region 84 are each 0.005 to 1.0 g / m 2 is preferable, and 0.02 to 0.04 g / m 2 is more preferred.

[0060] The basis weights of the third forming region 83 and the fourth forming region 84 can be controlled, for example, by changing the application pattern of the adhesive layer 74, similar to the above-mentioned first forming region 81 and second forming region. Alternatively, the basis weights of the third forming region 83 and the fourth forming region 84 can be controlled by changing the application amount even if the application pattern is the same.

[0061] The third forming region 83 and the fourth forming region 84 may be provided intermittently along the longitudinal direction LD of the separator 70. However, the total length over which the third forming region 83 (fourth forming region 84) is formed is preferably 60% or more, and more preferably 70% or more, of the length of the longitudinal direction LD of the separator 70. This more suitably exhibits the effects of preventing the intrusion of foreign matter and the like as well as the effects of vibration resistance during use of the battery 100.

[0062] 13 is an enlarged view showing a schematic interface between the positive electrode 22, the negative electrode 24, and the separator 70 of the wound electrode body 20. As described above, the separator 70 of the battery 100 disclosed herein preferably has an adhesive layer 74 formed on at least the surface on the side that contacts the positive electrode 22. In this case, in a more preferred embodiment, at least a part of the third formation region 83 contacts the positive electrode active material layer 22a. This improves the adhesion between the positive electrode 22 and the separator 70, and at least one of the effects of vibration resistance, suppression of peeling of the separator 70, and prevention of inclusion of foreign matter is preferably exhibited.

[0063] When the adhesive layer 74 is formed on at least the surface of the separator 70 that contacts the positive electrode 22, it is preferable that at least a portion of the fourth formation region 84 contacts the positive electrode active material layer 22a. This, for example, suppresses the separator 70 from turning over.

[0064] In a further preferred embodiment, the wound electrode body 20 is wound so that the adhesive layer 74 of the separator 70 and the positive electrode active material layer 22a abut against each other, and at least a portion of the third formation region 83 abuts against the positive electrode active material layer 22a, and at least a portion of the fourth formation region 84 abuts against the positive electrode active material layer 22a. This allows the positive electrode 22 and the separator 70 to be more suitably bonded at both ends in the width direction TD of the wound electrode body 20, and the peeling of the separator 70 and the inclusion of foreign matter are highly suppressed, thereby realizing a high-quality battery 100.

[0065] As described above, from the viewpoint of liquid injection, it is preferable that the separator 70 does not have the adhesive layer 74 on the side that contacts the negative electrode 24. In this case, it is preferable that at least a part of the third formation region 83 in the stacking direction MD of the wound electrode body 20 is formed at a position overlapping the position where the negative electrode active material layer 24a is formed. This makes it difficult for the negative electrode 24 to bend, for example, and can suppress the negative electrode active material layer 24a from falling off from the negative electrode 24. In another preferable embodiment in this case, it is preferable that at least a part of the fourth formation region 84 in the stacking direction MD of the wound electrode body 20 is formed at a position overlapping the position where the negative electrode active material layer 24a is formed.

[0066] On the other hand, as described above, the separator 70 may have an adhesive layer 74 formed on the surface on the side that contacts the negative electrode 24. In this case, the wound electrode body 20 is wound so that the adhesive layer 74 of the separator 70 and the negative electrode active material layer 24a contact each other, and at least a part of the third formation region 83 may contact the negative electrode active material layer 24a. Also, at least a part of the fourth formation region 84 may contact the negative electrode active material layer 24a. This improves the adhesion between the negative electrode 24 and the separator 70 at the end of the wound electrode body 20 in the width direction TD, improving at least one of the effects of vibration resistance, suppression of curling of the separator 70, and prevention of foreign matter contamination.

[0067] The separator 70 may not have an adhesive layer 74 on the side that contacts the positive electrode 22. In this case, at least a part of the third formation region 83 in the stacking direction MD of the wound electrode body 20 may be formed in a position overlapping the position where the positive electrode active material layer 22a is formed. In this case, at least a part of the fourth formation region 84 in the stacking direction MD of the wound electrode body 20 may be formed in a position overlapping the position where the positive electrode active material layer 22a is formed.

[0068] The separator 70 may have an adhesive layer-free region where the adhesive layer 74 is not formed, in addition to the first forming region 81, the second forming region 82, the third forming region 83, and the fourth forming region 84 in which the adhesive layer 74 is formed. The adhesive layer-free region may be provided, for example, between the first forming region 81 and the second forming region 82, or between the first forming region 81 and the second forming region and the third forming region 83. Alternatively, the adhesive layer-free region may be provided between the first forming region 81 and the second forming region and the fourth forming region 84.

[0069] In addition, an adhesive layer-free region may be provided at both ends of the separator 70 in the longitudinal direction LD, or an adhesive layer-free region may be provided at either end of the longitudinal direction LD. Alternatively, an adhesive layer-free region may be provided at either end of the width direction TD, or an adhesive layer-free region may be provided at both ends of the separator 70 in the width direction TD. As an example, an adhesive layer-free region may be provided in a region where the separator 70 contacts a winding core used when winding the wound electrode body 20. In other words, an adhesive layer-free region may be provided at an end of the separator 70 on the winding start side in the longitudinal direction LD. This makes it possible to easily remove the constructed wound electrode body 20 from the winding core. In addition, it is preferable that the adhesive layer 74 is not formed on the outermost peripheral surface when the wound electrode body 20 is constructed. In other words, an adhesive layer-free region may be provided at an end of the separator 70 on the winding end side in the longitudinal direction LD. This allows, for example, the wound electrode body 20 to be suitably accommodated in the electrode body holder 29.

[0070] 13, at the bottom wall side end (lower end in FIG. 13) of the separator 70, an adhesive layer-free region N1 where the adhesive layer 74 is not formed may be provided below (outside) the fourth formation region 84. Here, the adhesive layer-free region N1 is a region where the adhesive layer 74 is not formed and the heat-resistant layer 73 is exposed. By providing the adhesive layer-free region N1 below the fourth formation region 84, it is possible to increase, for example, the impregnation of the electrolyte solution.

[0071] 13, the width from the lower end of the negative electrode active material layer 24a to the lower end of the region N1 of the separator 70 where no adhesive layer is formed, in other words, the protruding margin of the bottom wall side end of the separator 70 that protrudes downward (toward the bottom wall side end) from the lower end of the opposing negative electrode active material layer 24a, is defined as C1. The protruding margin C1 is a region of the separator 70 that does not face the negative electrode active material layer 24a. Here, the protruding margin C1 is larger than the width B1 of the region N1 where no adhesive layer is formed. In this case, it is preferable that the width B1 of the region N1 where no adhesive layer is formed and the protruding margin C1 satisfy 0≦B1≦C1. The width from the lower end of the opposing positive electrode active material layer 22a to the lower end of the adhesive layer-free region N1 is defined as D1. The width D1 is a region of the separator 70 that does not face the positive electrode active material layer 22a. Here, the width D1 is larger than the width B1 of the adhesive layer-free region N1. In this case, the width B1 and the width D1 preferably satisfy 0≦B1≦D1.

[0072] <Second embodiment> FIG. 14 is a view of a battery 200 according to the second embodiment, corresponding to FIG. 2. As shown in FIG. 14, the battery 200 includes a wound electrode body 120 instead of the wound electrode body 20. In the battery 200, the arrangement of the wound electrode body 120 is different from that of the first embodiment. Therefore, the battery 200 includes a positive electrode tab group 125 and a negative electrode tab group 127 instead of the positive electrode tab group 25 and the negative electrode tab group 27. The battery 200 includes a positive electrode current collector 150 and a negative electrode current collector 160 instead of the positive electrode current collector 50 and the negative electrode current collector 60. The battery 200 includes an internal insulating member 194 instead of the internal insulating member 94. Other than these, the battery 200 may be similar to the battery 100 of the first embodiment described above.

[0073] The wound electrode body 120 is housed inside the battery case 10 so that the winding axis WL here substantially coincides with the long side direction Y. A pair of curved portions 120r (see FIG. 15) face the bottom wall 12a and the sealing plate 14 of the exterior body 12. The flat portion 120f (see FIG. 15) faces the long side wall of the exterior body 12. An end face of the wound electrode body 120 (i.e., the lamination surface where the positive electrode 22 and the negative electrode 24 are laminated) faces a pair of short side walls 12c. The material, configuration, etc. of each part constituting the wound electrode body 120 may be the same as that of the wound electrode body 20 of the first embodiment.

[0074] The positive electrode tab group 125 is provided at one end of the long side direction Y of the wound electrode body 120 (the left end in FIG. 14). The negative electrode tab group 127 is provided at the other end of the long side direction Y of the wound electrode body 120 (the right end in FIG. 14). The negative electrode tab group 127 is provided at the end opposite to the positive electrode tab group 125 in the long side direction Y. A positive electrode current collector 150 is attached to the positive electrode tab group 125. The positive electrode tab group 125 is electrically connected to the positive electrode terminal 30 via the positive electrode current collector 150. A negative electrode current collector 160 is attached to the negative electrode tab group 127. The negative electrode tab group 127 is electrically connected to the negative electrode terminal 40 via the negative electrode current collector 160.

[0075] The internal insulating member 194 has a protrusion that protrudes from the inner surface of the sealing plate 14 toward the wound electrode body 120. This restricts movement of the wound electrode body 120 in the vertical direction Z. Therefore, even if the wound electrode body 120 is subjected to an impact such as vibration or dropping, it is difficult for the wound electrode body 120 to interfere with the sealing plate 14, and damage to the wound electrode body 120 can be suppressed.

[0076] FIG. 15 is a diagram showing an example of the positions of the first forming region 181 and the second forming region 182 in the wound electrode body 120, and corresponds to FIG. 8. In FIG. 15, the symbol MD indicates a direction that coincides with the short side direction X of the battery 200, and the symbol TD indicates a direction that coincides with the up-down direction Z of the battery 200. The configuration of the separators 170 and 171 may be the same as the separators 70 and 71 of the first embodiment described above. However, in the second embodiment, the wound electrode body 120 is housed sideways, so different symbols are used to distinguish it from the first embodiment. Similarly, in the second embodiment, at least one of the separators 170 and 171 may have a configuration to be described later.

[0077] The separator 170 has an adhesive layer on at least one surface. In the longitudinal direction of the separator 170, the basis weight (g / m 2) is changed. The separator 170 has a first forming region 181 on which an adhesive layer is formed and a second forming region 182 on which an adhesive layer is formed on its surface, and the basis weight of the adhesive layer in the first forming region 181 is smaller than the basis weight of the adhesive layer in the second forming region 182. The first forming region 181 and the second forming region 182 are repeatedly formed in the longitudinal direction of the separator 170. When the wound electrode body 120 is housed sideways, as shown in FIG. 15, the pair of curved portions 120r are formed on both ends of the battery 200 in the up-down direction Z. At this time, it is preferable that the first forming region 181 of the separator 170 is located on the flat portion 120f and the second forming region 182 is located on the curved portion 120r. This improves the permeability of the electrolyte in the flat portion 120f, stabilizes the interelectrode distance in the curved portion 120r, and reduces the battery resistance.

[0078] As in the first embodiment, the separator 170 may include a third formation region and a fourth formation region in which an adhesive layer is formed, in addition to the first formation region 181 and the second formation region 182. The separator 170 may also include an adhesive layer-free region in which no adhesive layer is formed.

[0079] <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 a motor mounted on a vehicle such as a passenger car or truck. The type of vehicle is not particularly limited, and examples thereof include a plug-in hybrid electric vehicle (PHEV), a hybrid electric vehicle (HEV), and an electric vehicle (BEV; Battery Electric Vehicle). The battery can be suitably used to construct a battery pack, since the variation in the battery reaction is reduced.

[0080] 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.

[0081] <First Modification> For example, in the first embodiment described above, a first forming region 81 having a relatively small basis weight and a second forming region 82 having a relatively large basis weight are repeatedly formed in the longitudinal direction LD of the separator 70 as shown in Fig. 7. However, the first forming region 81 and the second forming region 82 in the separator 70 do not have to be repeatedly formed.

[0082] FIG. 16 is a plan view showing a separator 270 according to the first modification. FIG. 16 is a view corresponding to FIG. 7 according to the first modification. When the wound electrode body 20 is constructed, the start side of the separator 270 is located at the center side of the wound electrode body 20, and the end side is located at the outer periphery side of the wound electrode body 20. Here, the center side of the wound electrode body 20 is less likely to be impregnated with the electrolyte and has low injectability compared to the outer periphery side. For this reason, the separator 270 according to the first modification has a first formation region 281 on its surface where the adhesive layer 74 is formed, and a second formation region 282 on which the adhesive layer 74 is formed, and the basis weight of the adhesive layer 74 in the first formation region 281 is smaller than the basis weight of the adhesive layer 74 in the second formation region 282, and in the longitudinal direction LD of the separator 270, the first formation region 281 is arranged on the start side of the winding, and the second formation region 282 is arranged on the end side of the winding. That is, a first forming region 281 with a relatively small basis weight is formed at the center side of the wound electrode body 20 where the liquid injectability is low. By not forming an excessive amount of the adhesive layer 74, the electrolyte can easily permeate the center side of the wound electrode body 20, improving the liquid injectability of the entire wound electrode body 20. In addition, by providing a second forming region 282 with a relatively large basis weight at the winding end side of the wound electrode body 20, springback can be sufficiently suppressed. Therefore, the formability and liquid injectability of the wound electrode body 20 are compatible.

[0083] In the separator 270, the length L2 in the longitudinal direction LD of the first forming region 281 and the length L3 in the longitudinal direction LD of the second forming region 282 are not particularly limited because they can be appropriately changed according to the size of the wound electrode body, etc. For example, the length L2 (L2 / Lb) in the longitudinal direction LD of the first forming region 281 relative to the length Lb in the longitudinal direction LD of the separator 270 is preferably 0.1 to 0.9, more preferably 0.2 to 0.8. In addition, the length L3 (L3 / Lb) in the longitudinal direction LD of the second forming region 282 relative to the length Lb in the longitudinal direction LD of the separator 270 is preferably 0.1 to 0.9, more preferably 0.2 to 0.8. The ratio (L2:L3) of the length L2 in the longitudinal direction LD of the first formation region 281 to the length L3 in the longitudinal direction LD of the second formation region 282 is, for example, preferably 10:90 to 90:10, and more preferably 20:80 to 80:20.

[0084] In the separator 270 according to the first modification, when the region from the end 271s on the winding start side to the center in the longitudinal direction LD is defined as the first forming region 281, and the region from the end 271e on the winding end side to the center in the longitudinal direction LD is defined as the second forming region 282, the basis weight of the adhesive layer 74 in the first forming region 281 may be adjusted to be smaller than the basis weight of the adhesive layer 74 in the second forming region 282. In other words, even if the first forming region 281 and the second forming region 282 each have a region with a large basis weight and a region with a small basis weight, the entire basis weight of the first forming region 281 may be adjusted to be smaller than the entire basis weight of the second forming region 282. For example, the adhesive layer 74 may be formed so that the basis weight gradually increases from the end 271s on the winding start side to the end 271e on the winding end side in the longitudinal direction LD of the separator 270.

[0085] As in the first embodiment, the separator 270 may have a third formation region and a fourth formation region in which an adhesive layer is formed, in addition to the first formation region 281 and the second formation region 282 in which the adhesive layer 74 is formed. The separator 270 may also have an adhesive layer-free region in which the adhesive layer 74 is not formed.

[0086] <Second Modification> FIG. 17 is a plan view showing a separator 370 according to the second modification. FIG. 17 is a view corresponding to FIG. 7 according to the second modification. According to the knowledge of the inventors, a gap is likely to occur between the separator and the positive electrode at the center side of the wound electrode body 20, and the positive electrode and the separator tend to peel off easily. For this reason, the separator 370 according to the second modification has a first forming region 381 on the surface where the adhesive layer 74 is formed and a second forming region 382 on the surface where the adhesive layer 74 is formed, and the basis weight of the adhesive layer 74 in the first forming region 381 is smaller than the basis weight of the adhesive layer 74 in the second forming region 382, ​​and in the longitudinal direction LD of the separator 370, the second forming region 382 is arranged at the start side of the winding and the first forming region 381 is arranged at the end side of the winding. That is, the second forming region 382 with a relatively large basis weight is formed at the center side of the wound electrode body 20 where the positive electrode and the separator are likely to peel off. This can favorably improve the formability of the wound electrode body 20. On the other hand, a first forming region 381 with a relatively small basis weight is formed at the end of the winding of the wound electrode body 20. This can suppress a decrease in the liquid injectability. Therefore, the formability and liquid injectability of the wound electrode body 20 are compatible.

[0087] In the separator 370, the length L4 in the longitudinal direction LD of the first forming region 381 and the length L5 in the longitudinal direction LD of the second forming region 382 are not particularly limited because they can be appropriately changed according to the size of the wound electrode body, etc. For example, the length L4 (L4 / Lc) in the longitudinal direction LD of the first forming region 381 relative to the length Lc in the longitudinal direction LD of the separator 370 is preferably 0.1 to 0.9, more preferably 0.2 to 0.8. In addition, the length L5 (L5 / Lc) in the longitudinal direction LD of the second forming region 382 relative to the length Lc in the longitudinal direction LD of the separator 370 is preferably 0.1 to 0.9, more preferably 0.2 to 0.8. The ratio (L4:L5) of the length L4 of the first formation region 381 in the longitudinal direction LD to the length L5 of the second formation region 382 in the longitudinal direction LD is, for example, preferably 10:90 to 90:10, and more preferably 20:80 to 80:20.

[0088] In the separator 370 according to the second modification, when the region from the end 371e on the winding end side to the center in the longitudinal direction LD is defined as the first forming region 381, and the region from the end 371s on the winding start side to the center in the longitudinal direction LD is defined as the second forming region 382, ​​the basis weight of the adhesive layer 74 in the first forming region 381 may be adjusted to be smaller than the basis weight of the adhesive layer 74 in the second forming region 382. In other words, even if the first forming region 381 and the second forming region 382 each have a region with a large basis weight and a region with a small basis weight, the entire basis weight of the first forming region 381 may be adjusted to be smaller than the entire basis weight of the second forming region 382. For example, the adhesive layer 74 may be formed so that the basis weight gradually decreases from the end 371s on the winding start side to the end 371e on the winding end side in the longitudinal direction LD of the separator 370.

[0089] As in the first embodiment, the separator 370 may include a third formation region and a fourth formation region in which an adhesive layer is formed, in addition to the first formation region 381 and the second formation region 382 in which the adhesive layer 74 is formed. The separator 370 may also include an adhesive layer-free region in which the adhesive layer 74 is not formed.

[0090] <Third Modification> FIG. 18 is a plan view showing a separator 470 according to the third modified example. FIG. 18 is a view corresponding to FIG. 7 according to the third modified example. FIG. 19 is a view for explaining the angle of formation of the second forming region according to the third modified example. The separator 470 according to the third modified example has a first forming region 481 in which the adhesive layer 74 is formed and a second forming region 482 in which the adhesive layer 74 is formed on its surface, and the basis weight of the adhesive layer 74 in the first forming region 481 is smaller than the basis weight of the adhesive layer 74 in the second forming region 482, and the second forming region 482 is arranged in a plurality of stripes inclined with respect to the longitudinal direction LD of the separator 470. This makes it possible to suppress springback even in a state in which the area in which the second forming region 482 having a relatively large basis weight is formed is smaller. Therefore, the first forming region 481 having a relatively small basis weight can be provided over a wider range, improving the liquid injectability. Therefore, the formability and liquid injectability of the wound electrode body 20 are compatible.

[0091] The second forming region 482 may be in the form of a plurality of stripes inclined in the same direction with respect to the longitudinal direction LD of the separator 470, or may be in the form of a plurality of stripes inclined in different directions. For example, as shown in FIG. 18, the second forming region 482 is preferably formed in the form of a plurality of stripes inclined radially from the upper end side to the lower end side in the width direction TD of the separator 470. This allows gas that may be generated in the event of a short circuit or the like to be suitably released to the upper end side. This further improves the safety of the battery 100.

[0092] 19, in the wound electrode body 20, the region is divided by line segments X1 and X2 extending perpendicularly from both ends of the gas exhaust valve 17 in the long side direction toward the bottom wall 12a, and the region directly below the gas exhaust valve 17 is defined as region G1, and the region not directly below the gas exhaust valve 17 is defined as region G2. The angle of the second forming region 482 with respect to the line segment X1 in the region G1 is defined as θ1, and the angle of the second forming region 482 with respect to the line segment X1 (or line segment X2) in the region G2 is defined as θ2. At this time, the angles θ1 and θ2 of the second forming region 482 located in the region G1 and the region G2, respectively, are preferably adjusted so that the gas flows favorably toward the gas exhaust valve 17. For example, the angle θ1 of the second forming region 482 located in the region G1 is preferably smaller than the angle θ2 of the second forming region 482 located in the region G2 (θ2>θ1). Furthermore, although not particularly limited, the angle θ1 is preferably 0°≦θ1<90°, more preferably 0°≦θ1<45°, and may be θ1=0°. Furthermore, although not particularly limited, the angle θ2 is preferably 0°<θ2<90°, and more preferably 0°<θ2<45°.

[0093] The adhesive layer 74 may be applied over the entire surface (solid coating) or in a predetermined pattern. For example, in the region G1 directly below the gas release valve 17, the adhesive layer 74 may be formed in a dot pattern or stripes extending in the width direction TD in a plan view. In addition, in the region G2 not directly below the gas release valve 17, the adhesive layer 74 may be formed in a stripes extending in the width direction TD in a plan view. This makes it possible to achieve at least one of the effects of improving the formability of the wound electrode body 20, improving the injection property, and improving the safety of the battery 100.

[0094] <Fourth Modification> FIG. 20 is a plan view showing a separator 570 according to the fourth modification. FIG. 20 is a view corresponding to FIG. 7 according to the fourth modification. FIG. 21 is a view for explaining the angle of formation of the second formation region according to the fourth modification. The separator 570 according to the fourth modification includes a first formation region 581 on which the adhesive layer 74 is formed and a second formation region 582 on which the adhesive layer 74 is formed on its surface. The adhesive layer 74 in the first formation region 581 has a smaller basis weight than the adhesive layer 74 in the second formation region 582, and the second formation region 582 is arranged in a plurality of stripes inclined with respect to the longitudinal direction LD of the separator 570. In the region G4 not directly below the gas release valve 17 of the battery 100, the separator 570 is formed in a plurality of stripes inclined radially from the lower end side to the upper end side in the width direction TD. This can improve the liquid injection property of the wound electrode body 20.

[0095] As shown in FIG. 21, in the wound electrode body 20, the region is divided by line segments X3 and X4 extending perpendicularly from both ends of the gas exhaust valve 17 in the long side direction toward the bottom wall 12a, and the region directly below the gas exhaust valve 17 is defined as region G3, and the region not directly below the gas exhaust valve 17 is defined as region G4. The center line in the long side direction of the flat part of the wound electrode body 20 is defined as line segment X5. The angle of the second forming region 582 with respect to the line segment X5 in the region G3 is defined as θ3, and the angle of the second forming region 582 with respect to the line segment X3 (or line segment X4) in the region G4 is defined as θ4. In this case, it is preferable that the angle θ3 of the second forming region 582 located in the region G3 is smaller than the angle θ4 of the second forming region 582 located in the region G4 (θ4>θ3). Furthermore, although not particularly limited, the angle θ3 is preferably 0°≦θ3<90°, more preferably 0°≦θ3<45°, and may be θ3=0°. Furthermore, although not particularly limited, the angle θ4 is preferably 0°<θ4<90°, and more preferably 0°<θ4<45°.

[0096] As described above, specific aspects of the technology disclosed herein include those described in the following sections. Item 1: A battery comprising a wound electrode body in which a strip-shaped positive electrode having a positive electrode active material layer and a strip-shaped negative electrode having a negative electrode active material layer are wound with a strip-shaped separator interposed therebetween, the separator having an adhesive layer on at least one surface thereof, and the adhesive layer is formed so that the basis weight of the adhesive layer changes in the longitudinal direction of the separator. Item 2: The battery described in item 1, wherein the separator has a first formation region and a second formation region in which the adhesive layer is formed, the basis weight of the adhesive layer in the first formation region is smaller than the basis weight of the adhesive layer in the second formation region, and the first formation region and the second formation region are repeatedly formed in the longitudinal direction of the separator. Item 3: The battery described in item 2, wherein the wound electrode body is flat and includes a flat portion and a curved portion, the first forming region is located in the flat portion, and the second forming region is located in the curved portion. Item 4: The battery according to item 2 or 3, wherein at least one of the length of each of the first forming regions and the length of each of the second forming regions changes in the longitudinal direction of the separator. Item 5: The battery according to any one of items 2 to 4, wherein the separator has a third formation region located closer to one end of the separator than the first formation region in a width direction perpendicular to the longitudinal direction of the separator, the adhesive layer is formed in the third formation region along the longitudinal direction of the separator, and the adhesive layer has a basis weight in the third formation region that is greater than the basis weight in the first formation region. Item 6: The battery according to item 5, wherein the wound electrode body is wound so that the adhesive layer and the positive electrode active material layer are in contact with each other, and at least a portion of the third formation region is in contact with the positive electrode active material layer. Item 7: The battery described in claim 5 or 6, wherein the wound electrode body is wound such that the adhesive layer and the negative electrode active material layer do not come into contact with each other, and at least a portion of the third formation region is formed in a position overlapping with a position where the negative electrode active material layer is formed in a stacking direction of the wound electrode body. Item 8: The battery according to any one of items 5 to 7, wherein the separator has a fourth formation region located at an end side in the width direction of the separator where the third formation region is not formed, the adhesive layer is formed in the fourth formation region along the longitudinal direction of the separator, and the adhesive layer in the fourth formation region has a basis weight greater than that of the first formation region. [Explanation of symbols]

[0097] 10 Battery case 20 Wound electrode body 20f flat area 20r curved section 22 Positive electrode 22a Cathode active material layer 24 Negative electrode 24a Negative electrode active material layer 30 Positive terminal 40 Negative terminal 50 Positive electrode current collector 60 Negative electrode current collector 70 Separator 71 Separator 72 Base material layer 73 Heat-resistant layer 74 Adhesive layer 81 1st formation area 82 Second formation area 83 Third formation area 84 4th formation area 100 batteries 120 Wound electrode body 120f flat area 120r curved section 170 Separator 171 Separator 181 1st formation area 182 Second formation area 200 batteries 270 Separator 281 1st formation area 282 Second formation area 370 Separator 381 1st formation area 382 Second formation area 470 Separator 481 1st formation area 482 Second formation area 570 Separator 581 1st formation area 582 Second formation area

Claims

1. a strip-shaped positive electrode having a positive electrode active material layer and a strip-shaped negative electrode having a negative electrode active material layer, and a strip-shaped separator is interposed between the strip-shaped positive electrode and the negative electrode; The separator has an adhesive layer on at least one surface, The battery, wherein the adhesive layer is formed so that a basis weight of the adhesive layer changes in a longitudinal direction of the separator.

2. the separator has a first forming region and a second forming region in which the adhesive layer is formed, a basis weight of the adhesive layer in the first formation region is smaller than a basis weight of the adhesive layer in the second formation region, The battery according to claim 1 , wherein the first forming region and the second forming region are repeatedly formed in a longitudinal direction of the separator.

3. The wound electrode body is flat and includes a flat portion and a curved portion, The first formation region is located on the flat portion, The battery of claim 2 , wherein the second forming region is located in the curved portion.

4. The battery according to claim 2 , wherein at least one of a length of each of the first forming regions and a length of each of the second forming regions changes in a longitudinal direction of the separator.

5. the separator has a third formation region located closer to one end of the separator than the first formation region in a width direction perpendicular to a longitudinal direction of the separator, In the third formation region, the adhesive layer is formed along the longitudinal direction of the separator, The battery according to claim 2 , wherein a basis weight of the adhesive layer in the third formation region is greater than a basis weight of the adhesive layer in the first formation region.

6. The wound electrode body is wound so that the adhesive layer and the positive electrode active material layer are in contact with each other, The battery according to claim 5 , wherein at least a portion of the third formation region abuts against the positive electrode active material layer.

7. the wound electrode body is wound so that the adhesive layer and the negative electrode active material layer do not come into contact with each other, The battery according to claim 5 , wherein at least a part of the third formation region is formed in a position overlapping a position where the negative electrode active material layer is formed in a stacking direction of the wound electrode body.

8. the separator has a fourth formation region located on an end side on a side where the third formation region is not formed in a width direction of the separator, In the fourth formation region, the adhesive layer is formed along the longitudinal direction of the separator, The battery according to claim 5 , wherein a basis weight of the adhesive layer in the fourth formation region is greater than a basis weight of the adhesive layer in the first formation region.

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