Battery

Abstract

To provide a battery with reduced internal resistance.SOLUTION: A battery 100 comprises an electrode body 20 that includes a positive electrode 22 with a positive electrode active material layer 22a, a negative electrode 24, and a separator 70. The separator 70 comprises an adhesive layer 74 on a surface opposed to the positive electrode 22. The adhesive layer 74 has: a first formation region 74M provided so as to be opposed to the positive electrode active material layer 22a; and a second formation region 74U provided so as to be protruded outside one end part of the positive electrode active material layer 22a in a vertical direction Z or a long side direction of the battery 100. A coating weight of the first formation region 74M is smaller than that of the second formation region 74U.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a battery.

Background Art

[0002] Conventionally, a battery including an electrode body including a positive electrode having a positive electrode active material layer, a negative electrode having a negative electrode active material layer, and a separator, and a rectangular parallelepiped battery case for housing the electrode body has been known. For example, Patent Document 1 discloses an 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, and a battery including the electrode body.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, according to the study by the present inventors, when the adhesive is applied thickly to the entire surface of the separator, conversely, it becomes difficult for the electrolytic solution to impregnate the inside of the electrode body, and the inter-pole distance between the positive and negative electrodes is rather increased by the thickness of the adhesive, resulting in an increase in the internal resistance. The present invention has been made in view of the above circumstances, and an object thereof is to provide a battery in which the demerits of forming the adhesive layer are suppressed and the internal resistance is reduced.

Means for Solving the Problems

[0005] The present invention provides a battery including an electrode body including a positive electrode having a positive electrode active material layer, a negative electrode having a negative electrode active material layer, and a separator, and a rectangular parallelepiped battery case that houses the electrode body. The separator includes an adhesive layer on at least a surface facing the positive electrode. The adhesive layer has a first formation region provided to face the positive electrode active material layer, and a second formation region provided to protrude outward from one end of the positive electrode active material layer facing the positive electrode in the vertical or long side direction of the battery. 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.

[0006] By making the basis weight of the first formation region facing the positive electrode active material layer smaller than the basis weight of the second formation region protruding outward from the end of the positive electrode active material layer, it is possible to suppress the demerits of forming an adhesive layer on the separator. That is, compared with the case where the adhesive is applied thickly over the entire surface of the separator, the impregnation property of the electrolyte solution in the electrode body (especially the positive electrode active material layer) is improved, the interelectrode distance between the positive and negative electrodes is narrowed, and the internal resistance can be relatively reduced.

[0007] In addition, by relatively increasing the basis weight of the second formation region, the merits of forming an adhesive layer on the separator can be enjoyed. For example, when the adhesive layer of the separator is adhered to the positive electrode, the separator is less likely to be curled, and the workability during battery construction can be improved. Furthermore, the entry of foreign matter between the separator and the positive electrode can be suppressed. Thereby, it is possible to suppress the occurrence of micro short circuits caused by metal foreign matter that dissolves due to the increase in the potential of the positive electrode during charging and precipitates on the negative electrode. Also, even when the battery is subjected to impacts such as vibration or dropping during use, the arrangement of the separator is less likely to shift, and the vibration resistance can be improved. Therefore, according to the technology disclosed herein, it is possible to enjoy the merits of forming an adhesive layer while suppressing the demerits of forming an adhesive layer.

Brief Description of the Drawings

[0008]

Figure 1

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Mode for Carrying Out the Invention

[0009] Hereinafter, some embodiments of the technology disclosed herein will be described with reference to the drawings. Matters other than those specifically mentioned in this specification and necessary for the implementation of the technology disclosed herein (for example, general configurations and manufacturing processes of batteries that do not characterize the present invention) can be grasped as design matters of those skilled in the art based on the prior art in the relevant field. The technology disclosed herein can be implemented based on the content disclosed in this specification and common general knowledge in the relevant field. In this specification, the notation "A to B" indicating a range shall include the meaning of "A or more and B or less" as well as the meanings of "exceeding A" and "less than B".

[0010] Note that in this specification, the term "battery" refers to all power storage devices capable of extracting electrical energy, and is a concept including primary batteries and secondary batteries. Also, in this specification, the term "secondary battery" refers to all power storage devices capable of repeated charge and discharge by the movement of charge carriers between a positive electrode and a negative electrode through an electrolyte. The electrolyte may be any of a liquid electrolyte (electrolyte solution), a gel electrolyte, and a solid electrolyte. Such secondary batteries include, in addition to so-called storage batteries (chemical batteries) such as lithium-ion secondary batteries and nickel-metal hydride batteries, capacitors (physical batteries) such as electric double layer capacitors. Hereinafter, embodiments in the case of targeting a lithium-ion secondary battery will be described.

[0011] <First Embodiment> FIG. 1 is a perspective view schematically showing a battery 100 according to the first embodiment. The battery 100 is preferably a secondary battery, more preferably a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. FIG. 2 is a schematic longitudinal sectional view taken along line II-II in FIG. 1. FIG. 3 is a schematic cross-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 reference signs L, R, F, Rr, U, and D in the drawings represent left, right, front, rear, upper, and lower, respectively. Also, the reference sign X in the drawings indicates the short side direction of the battery 100, the reference sign Y indicates the long side direction of the battery 100, and the reference sign Z indicates the vertical direction of the battery 100. However, these are merely directions for convenience of explanation and do not limit the installation form of the battery 100 in any way.

[0012] As shown in FIGS. 1 to 3, the battery 100 includes a battery case 10 (see FIG. 1), a plurality of wound electrode bodies 20 (see FIGS. 2 and 3), a positive electrode terminal 30 (see FIGS. 1 and 2), a negative electrode terminal 40 (see FIGS. 1 and 2), a positive electrode current collector 50 (see FIG. 2), and a negative electrode current collector 60 (see FIG. 2). Although not shown, the battery 100 further includes an electrolytic solution here. The battery 100 is a non-aqueous electrolyte secondary battery. Hereinafter, the specific configuration of the battery 100 will be described.

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

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

[0015] As shown in FIG. 2, the sealing plate 14 is provided with a liquid injection hole 15, a gas discharge valve 17, and terminal lead-out holes 18 and 19. The liquid injection hole 15 is a through hole for injecting an electrolytic solution into the battery case 10 after assembling the sealing plate 14 to the outer package 12. The liquid injection hole 15 is sealed by a sealing member 16 after the injection of the electrolytic solution. The gas discharge valve 17 is a thin-walled portion configured to break when the pressure in the battery case 10 reaches a predetermined value or more and discharge the gas in the battery case 10 to the outside.

[0016] As the electrolytic solution, those conventionally known and used in batteries can be used without particular limitation. As an example, a non-aqueous electrolytic solution in which a supporting salt is dissolved in a non-aqueous solvent can be mentioned. As an example of the non-aqueous solvent, carbonate solvents such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate can be mentioned. As an example of the supporting salt, fluorine-containing lithium salts such as LiPF6 can be mentioned. The electrolytic solution may contain additives as necessary.

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

[0018] As shown in FIGS. 3 and 4, in the battery 100 of the present embodiment, a plurality (specifically, two) of wound electrode bodies 20 are accommodated in the battery case 10. However, the number of wound electrode bodies arranged inside one exterior body 12 is not particularly limited and may be three or more (plural) or one. The detailed structure of the wound electrode body 20 will be described later. As shown in FIG. 2, a positive tab group 25 and a negative tab group 27 project above the wound electrode body 20. The battery 100 has a so-called upper tab structure in which the positive tab group 25 and the negative tab group 27 are located above the wound electrode body 20. As shown in FIG. 4, the positive tab group 25 is curved in a state of being joined to the positive current collector 50. Although not shown, similarly, the negative tab group 27 is curved in a state of being joined to the negative current collector 60.

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

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

[0021] In the battery 100, various insulating members are used to prevent conduction between the wound electrode body 20 and the battery case 10. For example, as shown in FIG. 1, the positive electrode external conductive member 32 and the negative electrode external conductive member 42 are insulated from the sealing plate 14 by an external insulating member 92. Further, as shown in FIG. 2, gaskets 90 are respectively attached to the terminal lead-out holes 18, 19 of the sealing plate 14. Thereby, it is possible to prevent the positive electrode terminal 30 and the negative electrode terminal 40 inserted through the terminal lead-out holes 18, 19 from conducting with 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. Thereby, it is possible to prevent the positive electrode current collector 50 and the negative electrode current collector 60 from conducting with the sealing plate 14. Note that, as also shown in the second embodiment described later, the internal insulating member 94 may be provided with a protruding portion protruding toward the wound electrode body 20.

[0022] Furthermore, the plurality of wound electrode bodies 20 are arranged inside the exterior body 12 while being covered by an electrode body holder 29 (see FIG. 3) made of an insulating resin sheet. This can prevent the wound electrode bodies 20 from coming into direct contact with the exterior body 12. Note that the material of each of the above-described insulating members is not particularly limited as long as it has a predetermined insulation property. Examples of such materials include synthetic resin materials such as polyolefin resins such as polypropylene (PP) and polyethylene (PE), perfluoroalkoxyalkane, and fluorine-based resins such as polytetrafluoroethylene (PTFE).

[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 laminating a strip-shaped positive electrode 22 and a strip-shaped negative electrode 24 while being insulated via two strip-shaped separators 70, and winding them in the longitudinal direction around a winding axis WL. Note that the reference sign LD in FIG. 5 and the like indicates the longitudinal direction (i.e., the conveyance direction) of the wound electrode body 20 and the separator 70 manufactured in a strip shape. The reference sign WD is a direction substantially orthogonal to the longitudinal direction LD, and indicates the winding axis direction (also the width direction) of the wound electrode body 20 and the separator 70. In the present embodiment, the winding axis direction WD is substantially parallel to the vertical direction Z of the battery 100 described above.

[0024] Here, the wound electrode body 20 has a flat outer shape. The wound electrode body 20 preferably has a flat shape. The flat wound electrode body 20 can be formed, for example, by flat pressing a cylindrically wound electrode body (cylindrical body). As shown in FIG. 3, the flat wound electrode body 20 has a pair of curved portions 20r with a curved outer surface and a pair of flat portions 20f with a flat outer surface connecting the pair of curved portions 20r.

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

[0026] FIG. 6 is an enlarged view schematically showing the interface between the positive electrode 22, the negative electrode 24, and the separator 70 of the wound electrode body 20. Note that the symbol MD in FIG. 6 indicates the lamination direction of the wound electrode body 20 and is a direction substantially parallel to the short side direction X of the battery 100 described above. Hereinafter, the specific configuration of the wound electrode body 20 in the present embodiment will be described.

[0027] As shown in FIG. 5, the positive electrode 22 is a strip-shaped member. The positive electrode 22 includes a strip-shaped positive electrode current collector 22c, a positive electrode active material layer 22a and a positive electrode protective layer 22p fixed on at least one surface of the positive electrode current collector 22c. As shown in FIG. 6, the positive electrode 22 faces the adhesive layer 74 of the separator 70. At least a part of the positive electrode 22 is adhered to the separator 70. From the viewpoint of battery performance, the positive electrode active material layer 22a is preferably formed on both surfaces of the positive electrode current collector 22c.

[0028] For each member constituting the positive electrode 22, conventionally known materials that can be used in a general battery (for example, a lithium ion secondary battery) can be used without particular limitation. For example, the positive electrode current collector 22c is preferably made of a conductive metal such as aluminum, an aluminum alloy, nickel, or stainless steel, and here it is a metal foil, specifically an aluminum foil.

[0029] In the positive electrode 22, as shown in FIG. 5, a plurality of positive electrode tabs 22t protrude outward (upper side in FIG. 5) from one end side in the winding axis direction WD. The direction in which the positive electrode tabs 22t protrude is substantially the same as the winding axis direction WD. The plurality of positive electrode tabs 22t are provided at predetermined intervals (intermittently) along the longitudinal direction LD. Here, the positive electrode tabs 22t are part of the positive electrode 22. The positive electrode tabs 22t are regions where the positive electrode active material layer 22a is not formed. A positive electrode protective layer 22p is provided on a part of the positive electrode tabs 22t here. However, the positive electrode protective layer 22p may not be provided on the positive electrode tabs 22t. At least a part of the positive electrode tabs 22t exposes the positive electrode current collector 22c. The positive electrode tabs 22t may be a member different from the positive electrode 22.

[0030] Here, the plurality of positive electrode tabs 22t are each trapezoidal. However, the shape of the positive electrode tabs 22t is not limited to this. Also, the sizes of the plurality of positive electrode tabs 22t are not particularly limited. The shape and size of the positive electrode tabs 22t can be appropriately adjusted depending on, for example, the state of connection to the positive electrode current collecting portion 50 and their formation positions. The plurality of positive electrode tabs 22t are laminated at one end portion (upper end portion in FIG. 5) in the winding axis direction WD of the positive electrode 22 to form a positive electrode tab group 25 (see FIG. 2).

[0031] 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 positive electrode current collector 22c. The width of the positive electrode active material layer 22a (the length in the winding axis direction WD; the same shall apply hereinafter) is smaller than the width of the negative electrode active material layer 24a. The positive electrode active material layer 22a contains a positive electrode active material capable of reversibly occluding and releasing charge carriers. The positive electrode active material is preferably a lithium transition metal composite oxide, and more preferably one containing Ni. As an example of the lithium transition metal composite oxide containing Ni, lithium nickel cobalt manganese composite oxide can be mentioned. The positive electrode active material layer 22a may contain optional components other than the positive electrode active material, such as a binder, a conductive material, various additive components, etc. The positive electrode active material layer 22a preferably contains a binder and a conductive material in addition to the positive electrode active material. The binder is typically made of resin, and among them, fluorine-based resins such as polyvinylidene fluoride (PVdF) are preferred. As the conductive material, carbon materials such as acetylene black (AB) are preferred.

[0032] 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 positive electrode current collector 22c. The positive electrode protective layer 22p is provided at the boundary portion between the positive electrode current collector 22c and the positive electrode active material layer 22a in the winding axis direction WD. Here, the positive electrode protective layer 22p is provided at one end of the positive electrode current collector 22c in the winding axis direction WD, specifically, at the end on the side where the positive electrode tab 22t is located (the upper end portion in FIG. 5). By providing the positive electrode protective layer 22p, it is possible to prevent the positive electrode 22 from coming into direct contact with the negative electrode active material layer 24a and causing an internal short circuit of the battery 100 when the separator 70 is damaged.

[0033] The positive electrode protective layer 22p contains an insulating inorganic filler. As an example of the inorganic filler, ceramic particles such as alumina can be mentioned. The positive electrode protective layer 22p may contain optional components other than the inorganic filler, such as a binder, a conductive material, various additive components, etc. The binder and the conductive material may be the same as those exemplified as being contained in the positive electrode active material layer 22a. However, the positive electrode protective layer 22p is not essential and can be omitted in other embodiments.

[0034] As shown in FIG. 5, the negative electrode 24 is a strip-shaped member. The negative electrode 24 includes a strip-shaped negative electrode current collector 24c and a negative electrode active material layer 24a fixed on at least one surface of the negative electrode current collector 24c. As shown in FIG. 6, the negative electrode 24 faces the base material layer 72 of the separator 70 here. The negative electrode 24 may be adhered to the base material layer 72 of the separator 70. From the viewpoint of battery performance, it is preferable that the negative electrode active material layer 24a is formed on both surfaces of the negative electrode current collector 24c.

[0035] For each member constituting the negative electrode 24, conventionally known materials that can be used in a general battery (for example, 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, and here it is a metal foil, specifically a copper foil.

[0036] In the negative electrode 24, as shown in FIG. 5, a negative electrode tab 24t protrudes outward (the upper side in FIG. 5) from one end side in the winding axis direction WD. The plurality of negative electrode tabs 24t are provided at predetermined intervals (intermittently) along the longitudinal direction LD. In the winding axis direction WD, the negative electrode tab 24t is provided at the end on the same side as the positive electrode tab 22t. The negative electrode tab 24t is a part of the negative electrode 24 here. The negative electrode tab 24t is a region where the negative electrode current collector 24c is exposed and the negative electrode active material layer 24a is not formed here. However, a part of the negative electrode active material layer 24a may protrude and adhere to the negative electrode tab 24t. Also, the negative electrode tab 24t may be a member separate from the negative electrode 24.

[0037] The plurality of negative electrode tabs 24t are trapezoidal in shape here. However, the shape and size of the plurality of negative electrode tabs 24t can be appropriately adjusted in the same manner as the positive electrode tab 22t. The plurality of negative electrode tabs 24t are laminated at one end (the upper end in FIG. 5) in the winding axis direction WD of the negative electrode 24 to form a negative electrode tab group 27 (see FIG. 2).

[0038] As shown in FIG. 5, the negative electrode active material layer 24a is provided in a strip shape along the longitudinal direction LD of the negative electrode current collector 24c. The width of the negative electrode active material layer 24a is larger than the width of the positive electrode active material layer 22a. Note that the width of the negative electrode active material layer 24a refers to the length in the winding axis direction WD of a portion having a substantially constant thickness. For example, even if a part of the negative electrode active material layer 24a protrudes and adheres to the negative electrode tab 24t, the portion of the negative electrode tab 24t is not included. The negative electrode active material layer 24a contains a negative electrode active material capable of reversibly occluding and releasing charge carriers. The negative electrode active material is preferably a carbon material such as graphite or a silicon material, for example. The negative electrode active material layer 24a may contain optional components other than the negative electrode active material, such as a binder, a conductive material, and various additive components. The negative electrode active material layer 24a preferably contains a binder in addition to the negative electrode active material. The binder preferably contains rubbers such as styrene-butadiene rubber (SBR) and celluloses such as carboxymethyl cellulose (CMC). The negative electrode active material layer 24a may contain a carbon material as a conductive material as necessary.

[0039] As shown in FIG. 5, the separator 70 is a strip-shaped member. The separator 70 is an insulating sheet in which a plurality of fine through holes through which charge carriers can pass are formed. The width of the separator 70 is larger than the width of the negative electrode active material layer 24a. By interposing the separator 70 between the positive electrode 22 and the negative electrode 24, contact between the positive electrode 22 and the negative electrode 24 can be prevented, and charge carriers (for example, lithium ions) can be moved between the positive electrode 22 and the negative electrode 24.

[0040] Here, two sheets of the separator 70 are used for one wound electrode body 20. The separator 70 preferably includes two sheets, that is, a first separator and a second separator, for one wound electrode body 20 as in the present embodiment. The technology disclosed herein is applied to at least one of the first separator and the second separator, and preferably to both. Also, here, the two separators have the same configuration, but they may have different configurations.

[0041] As shown in FIG. 6, the separator 70 includes a base material layer 72 and an adhesive layer 74 formed on a surface of the base material layer 72 facing the positive electrode 22. Here, a heat-resistant layer 73 is further provided between the base material layer 72 and the adhesive layer 74. The adhesive layer 74 constitutes the outermost surface on the side facing the positive electrode 22. The separator 70 is integrated with the positive electrode 22, for example, by heating or press molding, so that the adhesive layer 74 is adhered (e.g., pressure-bonded) to the positive electrode 22. As a result, the separator 70 is less likely to be curled, and the workability during the construction of the battery 100 can be improved. In addition, the entry of foreign matter between the separator 70 and the positive electrode 22 can be suppressed, and the occurrence of micro short circuits caused by metal foreign matter can be suppressed. Further, even when the battery 100 is subjected to impacts such as vibration or dropping during use, the arrangement of the separator 70 is less likely to shift, and the vibration resistance can be improved.

[0042] The separator 70 may or may not include the heat-resistant layer 73 and / or the adhesive layer 74 on the surface facing the negative electrode 24. As shown in FIG. 6, here, the separator 70 does not include the heat-resistant layer 73 and the adhesive layer 74 on the surface facing the negative electrode 24. The base material layer 72 constitutes the outermost surface on the side facing the negative electrode 24 here. The negative electrode 24 is preferably opposed to the base material layer 72. The separator 70 may be adhered to the negative electrode 24 via the base material layer 72, for example.

[0043] As the base material layer 72, a microporous membrane used for a separator of a conventionally known battery can be used without particular limitation. The base material layer 72 is preferably a porous sheet-like member. The base material layer 72 may have a single-layer structure or a structure of two or more layers, for example, a three-layer structure. It is preferable that at least the surface of the base material layer 72 facing the negative electrode 24 is made of a polyolefin resin. More preferably, the entire base material layer 72 is made of a polyolefin resin. Thereby, sufficient flexibility of the separator 70 can be ensured, and the production (winding and press molding) of the wound electrode body 20 can be easily carried out. As the polyolefin resin, polyethylene (PE), polypropylene (PP), or a mixture thereof is preferable, and it is more preferable that it is made of PE.

[0044] Although not particularly limited, the thickness of the base material layer 72 (the length in the stacking direction MD; the same shall apply hereinafter) is preferably 3 to 25 μm, more preferably 3 to 18 μm, and even more preferably 5 to 14 μm. The air permeability of the base material layer 72 is preferably 30 to 500 sec / 100cc, more preferably 30 to 300 sec / 100cc, and even more preferably 50 to 200 sec / 100cc. The base material layer 72 may have adhesiveness to the extent that it can be adhered to the negative electrode active material layer 24a by, for example, heating or press molding.

[0045] The heat-resistant layer 73 is provided on the base material layer 72. It is preferable that the heat-resistant layer 73 is formed on the base material layer 72. The heat-resistant layer 73 may be provided directly on the surface of the base material layer 72, or may be provided on the base material layer 72 via another layer. However, the heat-resistant layer 73 is not essential and can be omitted in other embodiments. Here, the heat-resistant layer 73 is provided on the entire surface of the base material layer 72 facing the positive electrode 22. Thereby, the heat shrinkage of the separator 70 can be more accurately suppressed, contributing to the improvement of the safety of the battery 100. The heat-resistant layer 73 does not have adhesiveness to the extent that it can be adhered to the positive electrode active material layer 22a by, for example, heating or press molding. The basis weight of the heat-resistant layer 73 is uniform in the longitudinal direction LD and the winding axis direction WD of the separator 70 here. Although not particularly limited, the thickness of the heat-resistant layer 73 is preferably 0.3 to 6 μm, more preferably 0.5 to 6 μm, and even more preferably 1 to 4 μm. The heat-resistant layer 73 preferably contains an inorganic filler and a heat-resistant layer binder.

[0046] As the inorganic filler, those conventionally known and used in this kind of application can be used without particular limitation. The inorganic filler preferably contains insulating ceramic particles. Among them, considering heat resistance, availability, etc., inorganic oxides such as alumina, zirconia, silica, titania, etc., metal hydroxides such as aluminum hydroxide, and clay minerals such as boehmite are preferable, and alumina and boehmite are more preferable. Further, from the viewpoint of suppressing the heat shrinkage of the separator 70, compounds containing aluminum in particular are preferable. The ratio of the inorganic filler to the total mass of the heat-resistant layer 73 is preferably 85% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more.

[0047] As the heat-resistant layer binder, those conventionally known and used in this kind of application can be used without particular limitation. Specific examples include acrylic resins, fluorine-based resins, epoxy resins, urethane resins, ethylene vinyl acetate resins, etc. Among them, acrylic resins are preferable.

[0048] The adhesive layer 74 is provided on the surface facing the positive electrode 22 and is in contact with the positive electrode 22. As shown in FIG. 6, the adhesive layer 74 is preferably formed at least on the surface of the separator 70 on the positive electrode 22 side. Thereby, the above-described effects are more favorably exhibited. The adhesive layer 74 is adhered to the positive electrode 22, for example, by heating or pressing (typically press molding).

[0049] Here, the adhesive layer 74 is provided on the heat-resistant layer 73. The adhesive layer 74 is preferably formed on the heat-resistant layer 73. The adhesive layer 74 may be provided directly on the surface of the heat-resistant layer 73, or may be provided on the heat-resistant layer 73 via another layer. Further, it may be provided directly on the surface of the base material layer 72, or may be provided on the base material layer 72 via a layer other than the heat-resistant layer 73. The configuration of the adhesive layer 74 is not particularly limited and may be the same as those conventionally known. The adhesive layer 74 may be a layer having a relatively high affinity with the electrolytic solution compared to, for example, the heat-resistant layer 73 and absorbing and swelling with the electrolytic solution. The adhesive layer 74 contains an adhesive layer binder.

[0050] As the next layer binder, a conventionally known resin material having a certain viscosity with respect to the positive electrode 22 can be used without particular limitation. Specific examples include acrylic resins, fluorine-based resins, epoxy resins, urethane resins, ethylene vinyl acetate resins, and the like. Among them, fluorine-based resins and acrylic resins are preferable because they have high flexibility and can more suitably exhibit adhesiveness to the positive electrode 22. Examples of the fluorine-based resin include polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), and the like. The type of the adhesive layer binder may be the same as or different from that of the heat-resistant layer binder. The ratio of the heat-resistant layer binder to the total mass of the adhesive layer 74 is preferably 20% by mass or more, more preferably 50% by mass or more, and even more preferably 70% by mass or more. Thereby, a predetermined adhesiveness is accurately exhibited with respect to the positive electrode 22, and the separator 70 is likely to be deformed in press molding.

[0051] In addition to the adhesive layer binder, the adhesive layer 74 may contain other materials (for example, inorganic fillers listed as components of the heat-resistant layer 73). When the adhesive layer 74 contains an inorganic filler, the ratio of the inorganic filler to the total mass of the adhesive layer 74 is preferably 80% by mass or less, more preferably 50% by mass or less, and even more preferably 30% by mass or less.

[0052] FIG. 7 is a plan view showing the surface of the separator 70 on the side facing the positive electrode 22. As shown in FIG. 7, the adhesive layer 74 is formed in an area smaller than that of the heat-resistant layer 73 in a plan view. That is, the heat-resistant layer 73 is exposed on a part of the surface of the separator 70 on the positive electrode 22 side. As shown in FIGS. 6 and 7, the adhesive layer 74 is here divided into three regions in the winding axis direction WD. The adhesive layer 74 has a first formation region 74M provided at the central portion in the winding axis direction WD, a second formation region 74U provided at one end (the upper end portions in FIGS. 6 and 7) in the winding axis direction WD, and a third formation region 74D provided at the other end (the lower end portions in FIGS. 6 and 7) in the winding axis direction WD. In the winding axis direction WD, the third formation region 74D is provided at the end on the side opposite to the second formation region 74U. However, the third formation region 74D is not essential and can also be omitted in other embodiments. Also, in other embodiments, the second formation region 74U can be provided at the lower end portion in the winding axis direction WD.

[0053] As shown in FIG. 7, the first formation region 74M is provided between the second formation region 74U and the third formation region 74D in the winding axis direction WD. The first formation region 74M is formed linearly (in a strip shape) along the longitudinal direction LD of the separator 70. In the first formation region 74M, the surface of the adhesive layer 74 may be flat (so-called solid coating), but it is preferably uneven (with different thicknesses in part). In the first formation region 74M, the adhesive layer 74 itself may be partially formed. The adhesive layer 74 is preferably formed in a shape such as dot shape, stripe shape, wave shape, strip shape (rib shape), broken line shape, or a combination thereof in a plan view. Thereby, the impregnation property of the electrolytic solution into the wound electrode body 20 can be improved. In this specification, "the formation region is formed linearly" means that the formation region is linear, and the adhesive layer 74 itself may be in a dot shape or the like.

[0054] As shown in FIG. 6, the first formation region 74M is provided so as to face at least a part of the positive electrode active material layer 22a. Here, the width A of the first formation region 74M is smaller than the width of the positive electrode active material layer 22a. Although not particularly limited, the ratio of the width of the first formation region 74M to the width of the positive electrode active material layer 22a is preferably from 0.9 to 1.1, and more preferably from 0.95 to 1.05. Thereby, at least one of the above-described effects, for example, the effect of suppressing the curling of the separator 70 and the effect of improving the vibration resistance can be exhibited at a high level. Further, from the viewpoint of highly suppressing the entry of foreign matter between the separator 70 and the positive electrode active material layer 22a, it is preferable that the second formation region 74U and the end portion of the positive electrode active material layer 22a substantially overlap, and the above ratio is preferably from 0.9 to 1.0, and more preferably from 0.95 to 1.0.

[0055] In the technology disclosed herein, the basis weight of the adhesive layer 74 in the first formation region 74M is smaller than the basis weight of the adhesive layer 74 in the second formation region 74U. Further here, the basis weight of the adhesive layer 74 in the first formation region 74M is smaller than the basis weight of the adhesive layer 74 in the third formation region 74D. By setting the basis weight of the adhesive layer 74 as "the first formation region 74M < the second formation region 74U", the impregnation property of the electrolytic solution of the wound electrode body 20 (particularly the positive electrode active material layer 22a) can be improved, and the inter-pole distance between the positive electrode 22 and the negative electrode 24 can be narrowed to reduce the internal resistance.

[0056] The basis weight of the adhesive layer 74 in the first formation region 74M is preferably 0.005 g / m 2 or more, more preferably 0.01 g / m 2 or more, and still more preferably 0.02 g / m 2 or more. Further, preferably 2.0 g / m 2 or less, more preferably 1.0 g / m 2 or less, and still more preferably 0.05 g / m 2 or less. Thereby, the above-described effects can be exhibited at a higher level. In the present specification, "basis weight" means a value obtained by dividing the mass of the adhesive layer 74 by the area of the formation region (mass of the adhesive layer 74 / area of the formation region).

[0057] As shown in FIG. 7, the second formation region 74U is provided on the upper end side in the winding axis direction WD with respect to the first formation region 74M. The second formation region 74U is linearly (continuously) formed along the longitudinal direction LD of the separator 70. The second formation region 74U is formed in parallel with the first formation region 74M. The second formation region 74U is continuously formed from the upper end of the first formation region 74M. The second formation region 74U is in contact with the first formation region 74M, and there is no gap between the first formation region 74M and the second formation region 74U in the winding axis direction WD. In the second formation region 74U, the surface of the adhesive layer 74 may be flat (so-called solid coating) or may have unevenness. In the second formation region 74U, the adhesive layer 74 may be formed in a shape such as dot shape or stripe shape in plan view. The second formation region 74U is an example of "the second formation region provided so as to protrude outside one end of the opposing positive electrode active material layer 22a".

[0058] As shown in FIG. 6, here the second formation region 74U is located above the upper end of the first formation region 74M. In the wound electrode body 20, the second formation region 74U is arranged closer to the positive electrode tab group 25 than the first formation region 74M and the third formation region 74D. The second formation region 74U constitutes the tab side end portion of the separator 70. In the battery 100, the second formation region 74U is arranged closer to the sealing plate 14 than the first formation region 74M and the third formation region 74D.

[0059] The second formation region 74U is provided so as to at least protrude upward (outside) from the upper end of the opposing positive electrode active material layer 22a. The second formation region 74U is provided so as to face, for example, the positive electrode current collector 22c (specifically, the positive electrode tab 22t). Here, the second formation region 74U faces the end portion of the positive electrode active material layer 22a, the positive electrode protective layer 22p, and the positive electrode current collector 22c. The second formation region 74U preferably abuts on the positive electrode active material layer 22a. Thereby, at least one of the above-described effects, for example, the effect of suppressing the curling of the separator 70, the effect of preventing the inclusion of foreign matter, and the effect of improving vibration resistance can be exhibited at a high level, and in particular, the effect of improving vibration resistance can be enhanced.

[0060] The second formation region 74U is preferably provided so as to cover the upper end in the winding axis direction WD of the positive electrode active material layer 22a. Further, the second formation region 74U is preferably provided such that its position in the stacking direction MD overlaps with the negative electrode active material layer 24a. In other words, it is preferable that the upper end of the second formation region 74U is located above (outside) the upper end of the negative electrode active material layer 24a. The width of the second formation region 74U is smaller than the width of the first formation region 74M here. Although not particularly limited, when the interval I1 (see FIG. 6) from the upper end of the positive electrode active material layer 22a to the upper end of the negative electrode active material layer 24a is taken as 1 (reference), the width of the second formation region 74U is, for example, in the range of 0.5 to 2.5, preferably 0.8 to 2.3, more preferably 1.0 to 2.0.

[0061] The basis weight of the adhesive layer 74 in the second formation region 74U is larger than the basis weight of the adhesive layer 74 in the first formation region 74M. Thereby, the tendency of the separator 70 to shrink can be preferably suppressed. The basis weight of the adhesive layer 74 in the second formation region 74U is 0.005 g / m 2 or more is preferable, 0.01 g / m 2 or more is more preferable, 0.02 g / m 2 or more is even more preferable. Further, 2.0 g / m 2 or less is preferable, 1.0 g / m 2 or less is more preferable, 0.05 g / m 2The following is more preferable. Further, the ratio of the basis weight of the second formation region 74U to the basis weight of the first formation region 74M (second formation region 74U / first formation region 74M) is preferably from 1.01 to 50, more preferably from 1.10 to 30, and even more preferably from 1.50 to 10. Thereby, the above-described effects can be exhibited at a higher level.

[0062] As shown in FIG. 7, the third formation region 74D is provided on the lower end side in the winding axis direction WD than the first formation region 74M. The third formation region 74D is linearly (continuously) formed along the longitudinal direction LD of the separator 70. The third formation region 74D is formed in parallel with the first formation region 74M. The third formation region 74D is continuously formed from the lower end of the first formation region 74M. The third formation region 74D is in contact with the first formation region 74M, and there is no gap between the first formation region 74M and the third formation region 74D in the winding axis direction WD. In the third formation region 74D, the surface of the adhesive layer 74 may be flat (so-called solid coating) or may have unevenness. In the third formation region 74D, the adhesive layer 74 may be formed in a shape such as a dot shape or a stripe shape in plan view. The third formation region 74D is an example of "the third formation region provided so as to protrude outside the other end of the opposing positive electrode active material layer 22a".

[0063] As shown in FIG. 6, here, the third formation region 74D is located below the lower end of the first formation region 74M. In the battery 100, the third formation region 74D is disposed closer to the bottom wall 12a than the first formation region 74M and the second formation region 74U (in other words, on the side opposite to the sealing plate 14). The third formation region 74D constitutes the bottom wall side end portion of the separator 70. By having the third formation region 74D, the bottom wall side end portion of the separator 70 can be given firmness and the elasticity can be enhanced. Thereby, the third formation region 74D functions as a cushion for the wound electrode body 20, and the vibration resistance can be further improved.

[0064] The third formation region 74D is provided so as to at least protrude downward (outward) from the lower end of the opposing positive electrode active material layer 22a. The third formation region 74D is provided so as to directly face another separator 70 without interposing the positive electrode 22, for example. Here, the third formation region 74D faces the end of the positive electrode active material layer 22a and another separator 70. The third formation region 74D preferably abuts on the positive electrode active material layer 22a. Thereby, at least one of the above-described effects, for example, the effect of suppressing the curling of the separator 70, the effect of preventing the inclusion of foreign matter, and the effect of improving vibration resistance can be exhibited at a high level, and in particular, the effect of improving vibration resistance can be enhanced.

[0065] The third formation region 74D is preferably provided so as to cover the lower end in the winding axis direction WD of the positive electrode active material layer 22a. Further, the third formation region 74D is preferably provided so as to overlap the negative electrode active material layer 24a in the stacking direction MD. In other words, it is preferable that the lower end of the third formation region 74D is located above (outside) the lower end of the negative electrode active material layer 24a. The width of the third formation region 74D is smaller than the width of the first formation region 74M here. The width of the third formation region 74D is substantially the same as the width of the second formation region 74U here. However, as also described in a modification example to be described later, the width of the third formation region 74D may be larger than the width of the second formation region 74U. Further, it may be smaller than the width of the second formation region 74U. When the interval I2 (see FIG. 6) from the lower end of the positive electrode active material layer 22a to the lower end of the negative electrode active material layer 24a is set to 1 (reference), the width of the third formation region 74D is, for example, in the range of 0.5 to 2.5, preferably 0.8 to 2.3, more preferably 1.0 to 2.0.

[0066] The basis weight of the adhesive layer 74 in the third formation region 74D is larger than the basis weight of the adhesive layer 74 in the first formation region 74M. Thereby, it is possible to suitably suppress the separator 70 from shrinking. Further, by providing the third formation region 74D having such a basis weight, at least one of the above-described effects, for example, the effect of suppressing the curling of the separator 70, the effect of preventing the inclusion of foreign matter, and the effect of improving vibration resistance can be exhibited at a high level. The basis weight in the third formation region 74D may be the same as or different from the basis weight of the adhesive layer 74 in the second formation region 74U.

[0067] The basis weight of the adhesive layer 74 in the third formation region 74D is preferably 0.005 g / m 2 or more, more preferably 0.01 g / m 2 or more, and even more preferably 0.02 g / m 2 or more. Further, it is preferably 2.0 g / m 2 or less, more preferably 1.0 g / m 2 or less, and even more preferably 0.05 g / m 2 or less. Further, the ratio of the basis weight of the third formation region 74D to the basis weight of the first formation region 74M (third formation region 74D / first formation region 74M) is preferably 1.01 to 50, more preferably 1.10 to 30, and even more preferably 1.50 to 10. Thereby, the above-described effects can be exhibited at a higher level.

[0068] As shown in FIGS. 6 and 7, at the tab-side end portion (the upper end portion in FIGS. 6 and 7) of the separator 70, an unformed portion N1 in which the heat-resistant layer 73 is exposed without the adhesive layer 74 being formed is provided above (outside) the second formation region 74U. By providing the unformed portion N1 above the second formation region 74U, the gas permeability of the wound electrode body 20 can be improved, and the occurrence of gas biting can be suppressed. The width B1 of the unformed portion N1 is smaller than the width of the second formation region 74U here. Although not particularly limited, the width B1 of the unformed portion N1 (see FIG. 6) is preferably approximately 5 mm or less, for example, 1 to 3 mm, and is 1.7 mm here.

[0069] Here, as shown in FIG. 6, the width from the upper end of the negative electrode active material layer 24a to the upper end of the unformed portion N1 of the separator 70, in other words, the overhang of the tab side end portion of the separator 70 that protrudes above the upper end of the opposing negative electrode active material layer 24a (the side of the tab side end portion) is defined as C1. The overhang C1 is a region of the separator 70 that does not face the negative electrode active material layer 24a. At this time, it is preferable that the width B1 of the unformed portion N1 and the overhang C1 satisfy 0 < B1 ≤ C1. Also, the width from the upper end of the opposing positive electrode active material layer 22a to the upper end of the unformed portion 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. At this time, typically, the width C1 and the width D1 satisfy C1 < D1. Also, it is preferable that the width B1 and the width D1 satisfy 0 < B1 ≤ D1. Further, the distance I1 between the upper end of the positive electrode active material layer 22a and the upper end of the negative electrode active material layer 24a is larger than the width B1 of the unformed portion N1 here. Although not particularly limited, the distance I1 is preferably approximately 5 mm or less, for example, 1 to 3 mm, and is 2 mm here.

[0070] Also, as shown in FIGS. 6 and 7, at the bottom wall side end portion of the separator 70 (the lower end portion in FIGS. 6 and 7), below (outside) the third formation region 74D, an unformed portion N2 is provided where the heat-resistant layer 73 is exposed without the adhesive layer 74 being formed. By providing the unformed portion N2 below the third formation region 74D, the impregnation property of the electrolytic solution can be enhanced. The width B2 of the unformed portion N2 is smaller than the width of the third formation region 74D here. The width B2 of the unformed portion N2 is smaller than the width B1 of the unformed portion N1 on the tab side end portion side here. Although not particularly limited, the width B2 of the unformed portion N2 is preferably approximately 5 mm or less, for example, 1 to 3 mm, and is 1.6 mm here.

[0071] Here, as shown in FIG. 6, the width from the lower end of the negative electrode active material layer 24a to the lower end of the unformed portion N2 of the separator 70, in other words, the protrusion of the bottom wall side end portion of the separator 70 that protrudes below (the side of the bottom wall side end portion) the lower end of the opposing negative electrode active material layer 24a is defined as C2. The protrusion C2 is a region of the separator 70 that does not face the negative electrode active material layer 24a. The protrusion C2 is here approximately the same length as the protrusion C1 of the tab side end portion. However, the protrusion C2 may be longer or shorter than the protrusion C1. Also at this time, it is preferable that the width B2 of the unformed portion N2 and the protrusion C2 satisfy 0 < B2 ≤ C2. Further, the width from the lower end of the opposing positive electrode active material layer 22a to the lower end of the unformed portion N2 is defined as D2. The width D2 is a region of the separator 70 that does not face the positive electrode active material layer 22a. At this time, typically the width C2 and the width D2 satisfy C2 < D2. Also, it is preferable that the width B2 and the width D2 satisfy 0 ≤ B2 ≤ D2. Further, the interval I2 between the lower end of the positive electrode active material layer 22a and the lower end of the negative electrode active material layer 24a is here larger than the width of the unformed portion N2. Although not particularly limited, the interval I2 is generally 5 mm or less, for example, 1 to 3 mm, and here it is 1.6 mm.

[0072] FIG. 8 is a schematic diagram showing the upper end portion of the positive electrode 22 housed in the battery case 10. As shown in FIG. 8, the tab side end portion of the separator 70 can be in a bent state within the battery case 10, for example, by bending the positive electrode tab group 25 during the construction of the battery 100, or by contacting the sealing plate 14 or an internal insulating member 94 interposed between the sealing plate 14 and the wound electrode body 20. Here, the tab side end portions of the two opposing separators 70 are each bent toward the positive electrode active material layer 22a and are adhered to the opposing positive electrode current collector 22c in the region A1. The upper end of the positive electrode active material layer 22a is preferably covered by the two separators 70. By adhering the relatively large-areal second formation regions 74U to each other via the positive electrode current collector 22c, the tab side end portion of the separator 70 can be given strong stiffness. Thereby, even when subjected to impacts such as vibration and dropping, the positive electrode active material layer 22a is less likely to interfere with the sealing plate 14 or the internal insulating member 94, and damage to the positive electrode active material layer 22a can be suppressed.

[0073] FIG. 9 is a schematic view showing the lower end portion of the positive electrode 22 housed in the battery case 10. As shown in FIG. 9, the bottom wall side end portion of the separator 70 may be bent in the battery case 10 by being pressed against the bottom wall 12a of the exterior body 12 via the electrode body holder 29, for example, when the battery 100 is constructed, or by the self-weight of the wound electrode body 20 being applied. Here, the bottom wall side end portions of the two opposing separators 70 are each bent toward the positive electrode active material layer 22a, and the opposing third formation regions 74D are adhered to each other in region A2. The lower end of the positive electrode active material layer 22a is preferably covered by the two separators 70. By adhering the third formation regions 74D having a relatively large basis weight to each other, the bottom wall side end portion of the separator 70 can be made strong and its elasticity can be enhanced. As a result, even when the battery is subjected to impacts such as vibration or dropping, the positive electrode active material layer 22a is less likely to interfere with the bottom wall 12a, and damage to the positive electrode active material layer 22a can be suppressed.

[0074] <Second Embodiment> FIG. 10 is a view corresponding to FIG. 2 of the battery 200 according to the second embodiment. As shown in FIG. 10, 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. The battery 200 may be the same as the battery 100 of the first embodiment described above except for these.

[0075] The wound electrode body 120 is accommodated inside the battery case 10 such that the winding axis direction WD substantially coincides with the long side direction Y here. In other words, the wound electrode body 120 is disposed inside the battery case 10 in a direction where the winding axis direction WD is substantially parallel to the bottom wall 12a and the sealing plate 14 and substantially orthogonal to the long side wall 12b and the short side wall 12c. The pair of curved portions face the bottom wall 12a and the sealing plate 14 of the exterior body 12. The pair of flat portions face the long side wall of the exterior body 12. The end face of the wound electrode body 120 (that is, the laminated surface where the positive electrode 22 and the negative electrode 24 are laminated) faces the pair of short side walls 12c. Note that the materials, configurations, etc. of the respective portions constituting the wound electrode body 120 may be the same as those of the wound electrode body 20 of the first embodiment.

[0076] Unlike the first embodiment, the positive electrode tab group 125 is provided at one end in the long side direction Y (the left end in FIG. 10). The negative electrode tab group 127 is provided at the other end in the long side direction Y (the right end in FIG. 10). The negative electrode tab group 127 is provided at the end on the side opposite to the positive electrode tab group 125 in the long side direction Y. The battery 200 has a so-called horizontal tab structure in which the positive electrode tab group 125 and the negative electrode tab group 127 are positioned on the left and right sides of the wound electrode body 120. 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.

[0077] FIG. 11 is a diagram corresponding to FIG. 6 showing the configuration of the wound electrode body 120. Note that the symbol WD in FIG. 11 is substantially parallel to the long side direction Y of the battery 200. The separator 170 includes an adhesive layer 174. The configuration of the separator 170 may be the same as that of the separator 70 of the first embodiment described above. However, in this embodiment, since the wound electrode body 120 is housed horizontally, different reference numerals are used to distinguish it from the first embodiment. The adhesive layer 174 is divided here in the long side direction Y. The adhesive layer 174 has a first formation region 174M provided at the central portion in the long side direction Y, a second formation region 174L provided at one end in the long side direction Y (the left end in FIG. 11), and a third formation region 174R provided at the other end in the long side direction Y (the left end in FIG. 11).

[0078] The second formation region 174L is provided here at the end on the side of the positive electrode tab group 125. Similar to the first embodiment, the second formation region 174L preferably abuts on the positive electrode active material layer 22a. The third formation region 174R is provided here at the end on the side of the negative electrode tab group 127. Similar to the first embodiment, the third formation region 174R preferably abuts on the positive electrode active material layer 22a. The width of the third formation region 174R may be substantially the same as the width of the second formation region 174L, similar to the first embodiment. The width of the third formation region 174R may be smaller or larger than the width of the second formation region 174L.

[0079] The separator 170 preferably has an unformed portion N11 at the end on the side where the second formation region 174L in the long side direction Y is provided, in other words, at the end on the side of the positive electrode tab group 125 (FIG. 10). Further, the separator 170 preferably has an unformed portion N12 at the end on the side where the third formation region 174R in the long side direction Y is provided, in other words, at the end on the side of the negative electrode tab group 127 (FIG. 10). By having the unformed portion N11 and / or the unformed portion N12, it is possible to suppress the adhesive layer binder from protruding from the separator 170 and scattering around the coating device when forming the adhesive layer 174. Also, similar to the first embodiment, at least one of the gas permeability and the electrolyte impregnation property of the wound electrode body 20 can be improved.

[0080] Of the separator 170, the protrusion of the positive electrode tab group side end portion protruding outside (the left side in FIG. 11) from the end portion on the positive electrode tab group 125 side of the negative electrode active material layer 24a is defined as E, and the protrusion of the negative electrode tab group side end portion protruding outside (the right side in FIG. 11) from the end portion on the negative electrode tab group 127 side of the negative electrode active material layer 24a is defined as F. The protrusions E and F are regions not facing the negative electrode active material layer 24a of the separator 170. Here, the protrusion E is longer than the protrusion F. However, the protrusion E may be shorter than the protrusion F or may be substantially the same length as the protrusion F.

[0081] The internal insulating member 194 includes a protruding portion protruding from the inner surface of the sealing plate 14 toward the wound electrode body 120. Thereby, the movement of the wound electrode body 120 in the vertical direction Z is restricted. Therefore, even when receiving impacts such as vibration and dropping, the wound electrode body 120 is less likely to interfere with the sealing plate 14, and damage to the wound electrode body 120 can be suppressed.

[0082] <Battery applications> The battery 100 can be used for various applications. For example, it can be suitably used as a power source (driving power source) for a motor mounted on vehicles such as passenger cars and trucks. The type of vehicle is not particularly limited, and examples include plug-in hybrid electric vehicles (PHEV), hybrid electric vehicles (HEV), battery electric vehicles (BEV), and the like. Since the variation in battery reaction of the battery 100 is reduced, it can be suitably used for constructing a battery pack.

[0083] As described above, some embodiments of the present invention have been explained, but 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 content disclosed in this specification and common general knowledge in the art. The technology described in the claims includes various modifications and changes of the above-exemplified embodiments. For example, it is also possible to replace a part of the above-described embodiments with other modified forms, and it is also possible to add other modified forms to the above-described embodiments. Also, if its technical features are not described as essential, they can be appropriately deleted.

[0084] <First Modification Example> For example, in FIG. 7 described above, in the adhesive layer 74 of the separator 70, the second formation region 74U was continuously formed from the upper end of the first formation region 74M, and there was no gap between the first formation region 74M and the second formation region 74U. Also, the third formation region 74D was continuously formed from the lower end of the first formation region 74M, and there was no gap between the first formation region 74M and the third formation region 74D. However, it is not limited to this. In the first modification example, an adhesive layer non-formation region where the adhesive layer 74 is not formed may be provided between the first formation region 74M and the second formation region 74U, and / or between the first formation region 74M and the third formation region 74D.

[0085] FIG. 12 is a diagram corresponding to FIG. 7 of the separator 270 according to the first modification. The adhesive layer 274 of the separator 270 includes a first formation region 274M, a second formation region 274U, and a third formation region 274D. In the separator 270, gaps G1 and G2 are provided between the first formation region 274M and the second formation region 274U, and between the first formation region 274M and the third formation region 274D, respectively. The separator 270 may be the same as the above-described separator 70 except for this. By providing the gap G1 and / or the gap G2, the permeability of the electrolytic solution and / or the gas venting property can be improved. The gaps G1 and G2 are linearly (strip-shaped) formed along the longitudinal direction LD of the separator 270. Although not particularly limited, the widths of the gaps G1 and G2 are preferably 5 mm or less, more preferably 2 mm or less, and even more preferably 1 mm or less, respectively. The widths of the gaps G1 and G2 are preferably 0.05 mm or more, more preferably 0.1 mm or more, respectively.

[0086] <Second Modification> For example, in FIG. 7 described above, the width of the third formation region 74D was substantially the same as the width of the second formation region 74U. However, it is not limited to this. FIG. 13 is a diagram corresponding to FIG. 7 of the separator 370 according to the second modification. The adhesive layer 374 of the separator 370 includes a first formation region 374M, a second formation region 374U, and a third formation region 374D. In the separator 370, the width w2 of the third formation region 374D is larger than the width w1 of the second formation region 374U. The separator 370 may be the same as the above-described separator 70 except for this. By increasing the width of the third formation region 274D, the elasticity of the end portion on the bottom wall side of the separator 370 is increased, and more excellent vibration resistance can be realized. Although not particularly limited, the ratio (W2 / w1) of the width w2 to the width w1 is preferably approximately 1.2 to 3.0, for example, about 1.5 to 2.0.

[0087] <Third Modification> For example, in FIGS. 12 and 13 described above, the second formation regions 274U and 374U were formed continuously along the longitudinal direction LD of the separators 270 and 370. However, it is not limited to this. FIG. 14 is a diagram corresponding to FIG. 7 of the separator 470 according to the third modification. The adhesive layer 474 of the separator 470 includes a first formation region 474M, a second formation region 474U, and a third formation region 474D. In the separator 470, the second formation region 474U is formed at a predetermined interval H1 (intermittently) along the longitudinal direction LD. The interval H1 is an adhesive layer non-formation region where the second formation region 474U is not provided. In the interval H1, the heat-resistant layer 73 is exposed. The separator 470 may be the same as the separator 70 described above except for this. Although not particularly limited, in the longitudinal direction LD, the length of the interval H1 may be, for example, 5 mm or more, or 10 mm or more.

[0088] In one example, the interval H1 is provided in a portion that is disposed vertically below (directly below) the gas discharge valve 17 when the separator 470 is accommodated in the battery case 10. Thereby, gas can easily flow toward the gas discharge valve 17, and the gas in the battery case 10 can be quickly discharged to the outside. Therefore, safety can be improved. Also, in another example, the interval H1 is provided in a portion that is disposed vertically below (directly below) the liquid injection hole 15 when the separator 470 is accommodated in the battery case 10. Thereby, the impregnation property of the electrolytic solution can be improved. Also, in another example, the interval H1 is provided in a portion that is disposed at the curved portion 20r when the flat wound electrode body 20 is manufactured. Thereby, the elastic action generated from the curved portion 20r after press forming is suppressed to a small level, and the force (so-called springback) to restore to a cylindrical shape can be suppressed.

[0089] <Fourth Modification> For example, in FIG. 6 of the above-described first embodiment, the second formation region 74U and the third formation region 74D were in contact with the positive electrode active material layer 22a respectively. However, it is not limited thereto. For example, the second formation region 74U may not be in contact with the positive electrode active material layer 22a. In this case, the effect of improving vibration resistance can be enhanced, the gas permeability of the wound electrode body 20 can be improved, and the occurrence of gas biting can be suppressed. Furthermore, the impregnation property of the electrolytic solution can be enhanced. Also, the third formation region 74D may not be in contact with the positive electrode active material layer 22a. In this case, the effect of improving vibration resistance can be enhanced, and the impregnation property of the electrolytic solution can be enhanced.

[0090] Also, in FIG. 11 of the above-described second embodiment, the second formation region 174L and the third formation region 174R were in contact with the positive electrode active material layer 22a. However, it is not limited thereto. The second formation region 174L and / or the third formation region 174R may not be in contact with the positive electrode active material layer 22a. In this case, the impregnation property of the electrolytic solution can be enhanced, and the gas permeability of the wound electrode body 120 can be improved, and the occurrence of gas biting can be suppressed.

[0091] <Fourth Modification Example> In the above-described first and second embodiments, the electrode body 20 was a wound type (wound electrode body) using a strip-shaped positive electrode 22 and a strip-shaped negative electrode 24. However, it is not limited thereto. The electrode body can also be a stacked type (stacked electrode body) in which a rectangular positive electrode plate and a rectangular negative electrode plate are typically stacked in an insulated state, multiple sheets at a time.

[0092] As described above, specific aspects of the technology disclosed herein include those described in the following sections. Item 1: A battery comprising: an electrode body including a positive electrode having a positive electrode active material layer, a negative electrode having a negative electrode active material layer, and a separator; and a rectangular parallelepiped battery case that houses the electrode body, wherein the separator has an adhesive layer on at least the surface facing the positive electrode. The adhesive layer has a first formation region provided so as to face the positive electrode active material layer, and a second formation region provided so as to protrude outward beyond one end of the opposing positive electrode active material layer in the vertical direction or the long side direction of the battery. 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. Item 2: The battery according to Item 1, wherein the second formation region is in contact with the positive electrode active material layer. Item 3: The battery according to Item 1 or 2, wherein the adhesive layer further has a third formation region provided so as to protrude outward beyond the other end of the opposing positive electrode active material layer in the vertical direction or the long side direction of the battery, and the basis weight of the adhesive layer in the first formation region is smaller than the basis weight of the adhesive layer in the third formation region. Item 4: The battery according to Item 3, wherein the third formation region is in contact with the positive electrode active material layer. Item 5: The battery according to Item 3 or 4, wherein the battery case has an exterior body having an opening, a bottom wall facing the opening, and side walls extending from the edges of the bottom wall toward the opening, and a sealing plate that seals the opening. The electrode body is disposed inside the battery case such that the second formation region is located on the sealing plate side and the third formation region is located on the bottom wall side. In the vertical direction of the battery, the width of the third formation region is larger than the width of the second formation region. Item 6: The battery according to any one of Items 1 to 5, wherein the second formation region is intermittently formed along the vertical direction of the battery. Item 7: The battery according to Item 6, wherein the battery case has an exterior body having an opening, a bottom wall facing the opening, and side walls extending from the edges of the bottom wall toward the opening, and a sealing plate that seals the opening and is provided with a gas discharge valve. A portion where the second formation region is not formed is located vertically below the gas discharge valve. Item 8: The battery according to item 6 or 7, wherein the battery case has an exterior body having an opening, a bottom wall facing the opening, and side walls extending from the edge of the bottom wall toward the opening, is provided with a liquid injection hole for an electrolytic solution, and has a sealing plate for sealing the opening, and a portion where the second formation region is not formed is located vertically below the liquid injection hole.

Explanation of Signs

[0093] 10 Battery case 12 Exterior body 14 Sealing plate 20 Wound electrode body 22 Positive electrode 22a Positive electrode active material layer 22c Positive electrode current collector 24 Negative electrode 24a Negative electrode active material layer 24c Negative electrode current collector 70, 170, 270, 370, 470 Separator 72 Base material layer 73 Heat-resistant layer 74, 174, 274, 374, 474 Adhesive layer 74M, 174M, 274M, 374M, 474M First formation region 74U, 174L, 274U, 374U Second formation region 74D, 174R, 274D, 374D Third formation region 100 Battery

Claims

1. A battery comprising: an electrode body including a positive electrode having a positive electrode active material layer, a negative electrode having a negative electrode active material layer, and a separator; and a rectangular parallelepiped battery case that houses the electrode body, wherein the separator has an adhesive layer on at least the surface facing the positive electrode, the adhesive layer has a first formation region provided so as to face the positive electrode active material layer, a second formation region provided so as to protrude outside one end of the opposing positive electrode active material layer in the vertical direction or the long side direction of the battery, and has 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, and the second formation region is formed intermittently along the vertical direction of the battery.

2. The second formation region is in contact with the positive electrode active material layer, The battery according to claim 1.

3. The adhesive layer further has a third formation region provided so as to protrude outside the other end of the opposing positive electrode active material layer in the vertical direction or the long side direction of the battery, a basis weight of the adhesive layer in the first formation region is smaller than a basis weight of the adhesive layer in the third formation region, The battery according to claim 1 or 2.

4. The third formation region is in contact with the positive electrode active material layer, The battery according to claim 3.

5. The battery case has an exterior body having an opening, a bottom wall facing the opening, and side walls extending from the edge of the bottom wall toward the opening, a sealing plate that seals the opening, the electrode body is disposed inside the battery case such that the second formation region is located on the sealing plate side and the third formation region is located on the bottom wall side, in the vertical direction of the battery, a width of the third formation region is larger than a width of the second formation region, The battery according to claim 3.

6. The battery case has an exterior body having an opening, a bottom wall facing the opening, and side walls extending from the edge of the bottom wall toward the opening, a sealing plate that seals the opening and includes a gas discharge valve, a portion where the second formation region is not formed is located vertically below the gas discharge valve, The battery according to claim 1.

7. The battery case has an exterior body having an opening, a bottom wall facing the opening, and side walls extending from the edge of the bottom wall toward the opening, a sealing plate that seals the opening and includes a liquid injection hole for an electrolytic solution, A portion where the second formation region is not formed is located vertically below the liquid injection hole. The battery according to claim 1.

8. A battery comprising: an electrode body including a positive electrode having a positive electrode active material layer, a negative electrode having a negative electrode active material layer, and a separator; and a rectangular parallelepiped battery case that houses the electrode body, The separator includes a base material layer, an adhesive layer disposed on at least a surface facing the positive electrode, and a heat-resistant layer disposed between the base material layer and the adhesive layer in the thickness direction. The adhesive layer is formed with an area smaller than that of the heat-resistant layer in a plan view, and a first formation region provided so as to face the positive electrode active material layer; a second formation region provided so as to protrude outside one end of the opposing positive electrode active material layer in the vertical direction or the long side direction of the battery; having A battery in which 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.

9. The heat-resistant layer includes an inorganic filler and a heat-resistant layer binder, The adhesive layer includes a resin material, The heat-resistant layer binder and the resin material are different from each other. The battery according to claim 8.

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