Battery

Abstract

To provide a battery of which reliability is appropriately improved.SOLUTION: In a battery 100, a plurality of cathode tabs 22t is provided in a cathode 22. The cathode 22 includes: a first area A1 which is positioned closer to one side than a winding axis WL of a wound electrode body 20 in a thickness direction X from one flat face 20f1 through the winding axis WL to the other flat face 20f2 in a cross-sectional view which is cut in a direction orthogonal to the winding axis WL of the wound electrode body 20; and a second area A2 which is positioned closer to the other side than the winding axis WL in the thickness direction X. In the first area A1, the cathode tabs 22t are provided in equal to or more than 80 percent of layers of the cathode 22. In the second area A2, a plurality of layers in which the cathode tabs 22t are formed is present in the layers to the fifth layer from the side of the winding axis WL, no cathode tab 22t is provided in the layers outside of the fifth layer from the side of the winding axis WL, and the plurality of cathode tabs 22t is laminated and joined to a cathode current collection part 50.SELECTED DRAWING: Figure 8

Description

[Technical field]

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

[0002] For example, Japanese Patent No. 6641116 discloses an electrode assembly in which a positive electrode and a negative electrode are wound with a separator interposed between them, and the positive electrode includes a plurality of positive electrode tabs, and the negative electrode includes a plurality of negative electrode tabs. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6641116 Summary of the Invention [Problem to be solved by the invention]

[0004] However, according to the investigations of the present inventors, it has been found that there is still room for improvement in the battery including the above-mentioned wound electrode body from the viewpoint of improving the reliability of the battery. [Means for solving the problem]

[0005] The battery disclosed herein is a battery including a flat wound electrode body in which a band-shaped first electrode and a band-shaped second electrode are wound with a band-shaped separator interposed therebetween, and the first electrode is provided with a plurality of first electrode tabs, and the first electrode, in a cross-sectional view taken in a direction perpendicular to the winding axis of the wound electrode body, has a first region located on one side of the winding axis of the wound electrode body in a thickness direction from one flat surface, passing through the winding axis, to the other flat surface, and a second region located on the other side of the winding axis in the thickness direction, and in the first region, the first electrode tabs are provided on more than 80% of the layers of the first electrode, and in the second region, there are a plurality of layers on which the first electrode tabs are formed in the layers from the winding axis side to the fifth layer, and the first electrode tabs are not provided on layers outer than the fifth layer from the winding axis side, and the plurality of first electrode tabs are stacked and joined to a collecting member. A battery having such a configuration is preferable because the reliability of the battery is suitably improved. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a perspective view showing a battery according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic vertical cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 2 is a schematic cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a schematic vertical cross-sectional view taken along line IV-IV in FIG. 2. [Diagram 5] FIG. 2 is a schematic diagram showing the configuration of a wound electrode body according to one embodiment. [Figure 6] FIG. 2 is a schematic diagram showing a wound electrode body according to one embodiment. [Figure 7] FIG. 2 is a schematic diagram showing the configuration of a positive electrode and a negative electrode according to one embodiment. [Figure 8] 4 is a schematic diagram showing the cross-sectional configuration of the wound electrode body of FIG. 3. [Figure 9] 9 is a schematic diagram showing the vicinity of the winding start end of the positive electrode and the vicinity of the winding start end of the negative electrode in FIG. 8. FIG. [Figure 10]FIG. 9 is an explanatory diagram for explaining a first region and a second region in FIG. 8. [Figure 11] FIG. 11 is a schematic longitudinal sectional view taken along line XI-XI in FIG. [Figure 12] FIG. 10 is a view corresponding to FIG. 10 according to another embodiment. [Figure 13] FIG. 10 corresponds to FIG. 10 in the prior art. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, some preferred embodiments of the technology disclosed herein will be described with reference to the drawings. It should be noted that matters other than those specifically mentioned in this specification and necessary for carrying out the present disclosure (for example, the general configuration and manufacturing process of a battery that does not characterize the present disclosure) can be understood as design matters of a person skilled in the art based on the conventional technology in the field. The present disclosure can be carried out based on the contents disclosed in this specification and the technical common sense in the field. In addition, the embodiments described here are not intended to limit the present disclosure in particular. In addition, the expression "A to B" indicating a range in this specification includes the meaning of "greater than A" and "smaller than B" as well as the meaning of "A or more and B or less."

[0008] In this specification, the term "battery" refers to a general term for an electricity storage device capable of extracting electric energy, and is a concept that includes primary batteries and secondary batteries. In addition, in this specification, the term "secondary battery" refers to a general electricity storage device that can be repeatedly charged and discharged by the movement of charge carriers between a positive electrode and a negative electrode via an electrolyte. The electrolyte may be any of a liquid electrolyte (electrolytic solution), a gel electrolyte, and a solid electrolyte. Such secondary batteries include so-called storage batteries (chemical batteries) such as lithium ion secondary batteries and nickel metal hydride batteries, as well as capacitors (physical batteries) such as electric double layer capacitors. In the following, an embodiment in which a lithium ion secondary battery is the subject will be described.

[0009] <Battery configuration> FIG. 1 is a perspective view showing a battery 100 according to the present embodiment. The battery 100 is preferably a secondary battery, and 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 transverse sectional view taken along line III-III in FIG. 1. FIG. 4 is a schematic longitudinal sectional view taken along line IV-IV in FIG. 2. In the following description, the symbols L, R, F, Rr, U, and D in the drawings represent left, right, front, rear, top, and bottom. In addition, the symbol X in the drawings indicates the short side direction of the battery 100, the symbol Y indicates the long side direction of the battery 100, and the symbol Z indicates the up-down direction of the battery 100. However, these are merely directions for convenience of explanation, and do not limit the installation form of the battery 100 in any way. In addition, the winding direction D1 in FIG. 8 is merely a direction for convenience, and does not limit the winding direction to this direction.

[0010] In this embodiment, the first electrode is the positive electrode 22 (i.e., the first electrode tab is the positive electrode tab 22t) and the second electrode is the negative electrode 24 (i.e., the second electrode tab is the negative electrode tab 24t), but it is not intended to limit the technology disclosed herein to such a form. In other embodiments, the first electrode may be the negative electrode 24 (i.e., the first electrode tab is the negative electrode tab 24t) and the second electrode may be the positive electrode 22 (i.e., the second electrode tab is the positive electrode tab 22t). On the other hand, since the material of the positive electrode current collector 22c constituting the positive electrode 22 is generally soft and easily broken, it is preferable that the first electrode is the positive electrode 22 because the effect of the technology disclosed herein can be easily obtained. In addition, the technology disclosed herein may be applied to at least the first electrode, but for example, when it is applied to the second electrode (here, the negative electrode 24) in addition to the first electrode (here, the positive electrode 22) as in this embodiment, it is preferable because the effect of the technology disclosed herein can be obtained more effectively.

[0011] 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 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. As shown in FIG. 1, the battery case 10 has a flat and bottomed rectangular parallelepiped (rectangular) outer shape. However, in other embodiments, the outer shape of the battery case 10 may be other shapes such as a cylindrical shape. A laminated case may also be used as the housing. As shown in FIG. 2, the battery case 10 includes an exterior body 12 having an opening 12h and a sealing plate (lid body) 14 that seals the opening 12h. The material of the battery case 10 (exterior body 12 and sealing plate 14) may be the same as that used conventionally and is not particularly limited. The battery case 10 is preferably made of metal, and more preferably made of, for example, aluminum, an aluminum alloy, iron, an iron alloy, or the like. The exterior body 12 and sealing plate 14 constituting the battery case 10 may be made of the same material or different materials. The exterior body 12 and the sealing plate 14 have sizes according to the number of wound electrode bodies 20 they will accommodate (one or more. Here, more than one), their sizes, and the like.

[0013] As can be seen from Figs. 1 and 2, the exterior body 12 is a bottomed, rectangular container having an opening 12h on the upper surface. As shown in Fig. 1, the exterior body 12 includes a bottom wall 12a, a pair of long side walls 12b that extend upward from the long side of the bottom wall 12a and face each other, and a pair of short side walls 12c that extend upward from the short side of the bottom wall 12a and face each other. The long side walls 12b and the short side walls 12c are examples of the first side walls and the second side walls disclosed herein. The area of ​​the long side walls 12b is larger than the area of ​​the short side walls 12c. 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 planar, substantially rectangular, plate-like member attached to the exterior body 12 so as to close the opening 12h of the exterior body 12. The sealing plate 14 faces the bottom wall 12a of the exterior body 12. The sealing plate 14 has a substantially rectangular shape. 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. This makes the battery case 10 airtightly sealed (sealed).

[0014] 2, the sealing plate 14 is provided with a liquid injection hole 15, a gas exhaust valve 17, and terminal withdrawal holes 18 and 19. The liquid injection hole 15 is a through hole for injecting an electrolyte into the battery case 10 after the sealing plate 14 is assembled to the exterior body 12. The liquid injection hole 15 is sealed with a sealing member 16 after the electrolyte is injected. The gas exhaust valve 17 is a thin-walled portion configured to break when the pressure inside the battery case 10 reaches or exceeds a predetermined value, thereby discharging gas inside the battery case 10 to the outside.

[0015] The electrolyte may be any electrolyte used in conventional batteries without any particular limitations. An example of the electrolyte is a non-aqueous electrolyte in which a supporting salt is dissolved in a non-aqueous solvent. An example of the non-aqueous solvent is a carbonate-based solvent such as ethylene carbonate, dimethyl carbonate, or ethyl methyl carbonate. An example of the supporting salt is a fluorine-containing lithium salt such as LiPF6. The electrolyte may contain an additive as necessary.

[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] As shown in Figs. 3 and 4, in the battery 100 of this embodiment, a plurality of (specifically, two) wound electrode bodies 20 are accommodated in the battery case 10. However, the number of wound electrode bodies arranged inside one exterior body 12 is not particularly limited, and may be three or more (multiple), or may be one. The detailed structure of the wound electrode body 20 will be described later, but as shown in Fig. 2, a positive electrode tab group 25 and a negative electrode tab group 27 protrude from the upper part of the wound electrode body 20. The battery 100 has a so-called upper tab structure in which the positive electrode tab group 25 and the negative electrode tab group 27 are located above the wound electrode body 20.

[0018] As shown in FIG. 4, the positive electrode tab group 25 is joined to the positive electrode current collector (positive electrode current collector) 50 in a curved state. This configuration is preferable because it can more suitably improve the volumetric energy density of the battery 100. Although not shown in the figures, the negative electrode tab group 27 is similarly joined to the negative electrode current collector (negative electrode current collector) 60 in a curved state. In addition, the positive electrode tab group 25 is preferably joined to a region of the positive electrode current collector 50 that is arranged along the wall of the battery case (preferably, the sealing plate 14). Similarly, the negative electrode tab group 27 is preferably joined to a region of the negative electrode current collector 60 that is arranged along the wall of the battery case (preferably, the sealing plate 14).

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

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

[0021] In the battery 100, various insulating members are used to prevent conduction between the wound electrode body 20 and the battery case 10. For example, as shown in FIG. 1, the positive electrode external conductive member 32 and the negative electrode external conductive member 42 are insulated from the sealing plate 14 by an external insulating member 92. Also, as shown in FIG. 2, a gasket 90 is attached to each of the terminal pull-out holes 18 and 19 of the sealing plate 14. This can prevent the positive electrode terminal 30 and the negative electrode terminal 40 inserted into the terminal pull-out holes 18 and 19 from being conducted to the sealing plate 14. Also, an internal insulating member 94 is disposed between the positive electrode current collector 50 and the negative electrode current collector 60 and the inner surface side of the sealing plate 14. This can prevent the positive electrode current collector 50 and the negative electrode current collector 60 from being conducted to the sealing plate 14. The internal insulating member 94 may have a protruding portion that protrudes toward the wound electrode body 20.

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

[0023] 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 an insulated state via two strip-shaped separators 70 (a first separator 70A and a second separator 70B) and winding them in the longitudinal direction around the winding axis WL. The symbol LD in FIG. 5 and other figures indicates the longitudinal direction (i.e., the conveying direction) of the wound electrode body 20 and the separator 70 manufactured in a strip shape. The symbol WD is a direction approximately perpendicular to the longitudinal direction LD and indicates the winding axis direction (also the width direction) of the wound electrode body 20 and the separator 70. The winding axis direction WD is approximately parallel to the up-down direction Z of the battery 100 described above.

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

[0025] FIG. 6 is a schematic diagram showing the wound electrode body 20. P in FIG. 6 indicates the height of the wound electrode body 20 (in other words, the length in the direction along the winding axis WL of the wound electrode body 20. It is also referred to as the length in the direction connecting the bottom wall 12a of the exterior body 12 and the sealing plate 14). Q in FIG. 6 indicates the width of the wound electrode body 20 (in other words, the length in the direction perpendicular to the thickness direction X of the wound electrode body 20. It is also referred to as the length in the direction connecting the pair of short side walls 12c of the exterior body 12). Here, the ratio (Q / P) of the width Q of the wound electrode body 20 to the height P of the wound electrode body 20 is not particularly limited as long as the effect of the technology disclosed here is exerted, but is, for example, 2 or more, and from the viewpoint of improving the circulation of the electrolyte and more suitably improving the high-rate characteristics and the rapid charging characteristics, is preferably 3 or more, and may be, for example, 4 or more. The upper limit of the ratio (Q / P) is not particularly limited, but may be, for example, 10 or less, 7 or less, or 5 or less. The height P of the wound electrode body 20 is preferably 50 mm or more, and may be, for example, 100 mm or more. The height P of the wound electrode body 20 is preferably 200 mm or less, and more preferably 150 mm or less. The width Q of the wound electrode body 20 is preferably 100 mm or more, and more preferably 200 mm or more. The width Q of the wound electrode body 20 may be, for example, 600 mm or less, 500 mm or less, or 400 mm or less. However, it is not intended to be limited to these values.

[0026] T in Fig. 6 indicates the thickness of the wound electrode body 20. The thickness T of the wound electrode body 20 is not particularly limited as long as the effects of the technology disclosed herein are exhibited, but is, for example, 10 mm or more, and from the viewpoint of more suitably improving the volumetric energy of the battery 100, is preferably 12 mm or more, more preferably 15 mm or more, and even more preferably 20 mm or more. The upper limit of the thickness T of the wound electrode body 20 is not particularly limited, but may be, for example, 50 mm or less, 40 mm or less, or 30 mm or less. However, it is not intended to be limited to these values.

[0027] In the battery 100, the wound electrode body 20 is accommodated in the battery case 10 so that the winding axis direction WD is approximately aligned with the vertical direction Z. In other words, the wound electrode body 20 is disposed in the battery case 10 so that the winding axis direction WD is approximately parallel to the long side wall 12b and the short side wall 12c, and is approximately perpendicular to the bottom wall 12a and the sealing plate 14. That is, the wound electrode body 20 is disposed in the battery case 10 so that its winding axis WL is perpendicular to the bottom wall 12a. In this manner, the wound electrode body 20 is preferably configured to open at the top and bottom, since this improves the circulation of the electrolyte, and more suitably improves the high-rate characteristics and the rapid charging characteristics. In addition, this is preferable because the battery 100 can be a high-capacity battery. As shown in FIG. 3, the pair of curved portions 20r face the pair of short side walls 12c of the exterior body 12. The pair of flat portions 20f face the long side walls 12b of the exterior body 12. The end faces of the wound electrode body 20 (that is, the stacking surfaces where the positive electrode 22 and the negative electrode 24 are stacked, both ends in the winding axis direction WD in FIG. 5) face the bottom wall 12a and the sealing plate 14.

[0028] The positive electrode 22 is a strip-shaped member as shown in Fig. 5. The positive electrode 22 includes a strip-shaped positive electrode current 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 current collector 22c. From the viewpoint of battery performance, the positive electrode active material layer 22a is preferably formed on both sides of the positive electrode current collector 22c.

[0029] For each member constituting the positive electrode 22, conventionally known materials that can be used in general batteries (e.g., lithium ion secondary batteries) 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 is a metal foil, specifically an aluminum foil, in this case. The thickness of the positive electrode current collector 22c is preferably 5 μm to 30 μm, and more preferably 8 μm to 25 μm.

[0030] As shown in FIG. 5, the positive electrode 22 has a plurality of positive electrode tabs 22t protruding outward (upper side in FIG. 5) from one end side in the winding axis direction WD. The plurality of positive electrode tabs 22t are provided at predetermined intervals (intermittently) along the longitudinal direction LD. The positive electrode tabs 22t are a part of the positive electrode 22 here. The positive electrode tab 22t is a region where the positive electrode active material layer 22a is not formed. A positive electrode protective layer 22p is provided on a part of the positive electrode tab 22t here. However, the positive electrode protective layer 22p may not be provided on the positive electrode tab 22t. The positive electrode current collector 22c is exposed on at least a part of the positive electrode tab 22t. The positive electrode tab 22t may be a member separate from the positive electrode 22.

[0031] Here, each of the positive electrode tabs 22t is trapezoidal. However, the shape of the positive electrode tabs 22t is not limited to this. The size of the positive electrode tabs 22t is not particularly limited. The shape and size of the positive electrode tabs 22t can be appropriately adjusted depending on the formation position and the like, taking into consideration the state of connection to the positive electrode current collecting part 50, for example. In one embodiment, the length of the positive electrode tab 22t in the width direction (LD direction in FIG. 5) may be 10 mm to 30 mm (for example, 15 mm to 20 mm), and the length of the positive electrode tab 22t in the protruding direction (Z direction in FIG. 5) may be 10 mm to 30 mm (for example, 15 mm to 20 mm). The positive electrode tabs 22t are stacked at one end (upper end in FIG. 5) of the winding axis direction WD of the positive electrode 22 to configure a positive electrode tab group 25 (see FIG. 2). Here, FIG. 11 is a schematic vertical cross-sectional view taken along the line XI-XI in FIG. 10. As shown in Fig. 11, here, the length of the positive electrode tab 22t in the protruding direction (direction Z in Fig. 11) is gradually increased. Although not shown, the same is true for the negative electrode side.

[0032] FIG. 7 is a schematic diagram showing the configuration of the positive electrode 22 and the negative electrode 24. In FIG. 7 and FIG. 8, r a (r a1 ,r a2 ,r a3 , r a6 ,r a7 ,r a8 ) and r b (r b1 ,r b2 ,r b3 , r b5 ,r b6 ,r b7 ) indicates the apex of the curved portion 20r. As shown in FIG. 7, the first tab of the positive electrode 22 (here, the positive electrode tab 22t 1A2 In the second region A2, a notch v1 is formed in the first tab of the negative electrode 24 (here, negative electrode tab 24t). 1A2. In the second region A2, the negative electrode tab 24t located at the position closest to the winding axis WL in the thickness direction X is also referred to as the negative electrode tab 24t. A notch v2 is formed in the negative electrode tab 24t. This configuration is preferable because it is easier to detect the start of winding the positive electrode 22 and the negative electrode 24 when winding the positive electrode 22 and the negative electrode 24 around a winding roller described later. As shown in FIG. 7, the shapes of the notches v1 and v2 are semicircular here. The size of the notches v1 and v2 is about φ3 mm here. However, the shape of the notches is not limited to this, and can be various shapes such as a rectangle or an inverted triangle. The size of the notches is preferably adjusted appropriately depending on the size of the tabs.

[0033] 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 applies below) is smaller than the width of the negative electrode active material layer 24a. The positive electrode active material layer 22a contains a positive electrode active material capable of reversibly absorbing and releasing charge carriers. The positive electrode active material is preferably a lithium transition metal composite oxide, and more preferably contains at least one of Ni (nickel) and Co (cobalt). An example of such a lithium transition metal composite oxide is lithium nickel cobalt manganese composite oxide. 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 binder, a conductive material, and various additive components. 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, a fluorine-based resin such as polyvinylidene fluoride (PVdF) is preferable. The conductive material is preferably a carbon material such as acetylene black (AB). The density of the positive electrode active material layer 22a is 3.0 g / cm 3 More than 3.2 g / cm is preferable. 3In the case where the density of the positive electrode active material layer 22a is high in this way, the positive electrode current collector 22c is more likely to break, and therefore, this is a suitable subject for applying the effects of the technology disclosed herein.

[0034] 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 collector 22c. The positive electrode protective layer 22p is provided at the boundary between the positive electrode collector 22c and the positive electrode active material layer 22a in the winding axis direction WD. Here, the positive electrode protective layer 22p is provided at one end of the positive electrode collector 22c in the winding axis direction WD, specifically, at the end on the side where the positive electrode tab 22t is located (the upper end in FIG. 5). By providing the positive electrode protective layer 22p, it is possible to prevent the positive electrode 22 from directly contacting the negative electrode active material layer 24a when the separator 70 is damaged, and thus prevent the battery 100 from being internally short-circuited.

[0035] The positive electrode protective layer 22p contains an insulating inorganic filler. An example of the inorganic filler is ceramic particles such as alumina. The positive electrode protective layer 22p may contain any component other than the inorganic filler, such as a binder, a conductive material, and various additive components. The binder and the conductive material may be the same as those exemplified as those that may be contained in the positive electrode active material layer 22a. However, the positive electrode protective layer 22p is not essential and may be omitted in other embodiments.

[0036] The negative electrode 24 is a strip-shaped member as shown in Fig. 5. The negative electrode 24 includes a strip-shaped negative electrode current collector 24c and a negative electrode active material layer 24a fixed onto at least one surface of the negative electrode current collector 24c. From the viewpoint of battery performance, the negative electrode active material layer 24a is preferably formed on both sides of the negative electrode current collector 24c.

[0037] For each member constituting the negative electrode 24, conventionally known materials that can be used in general batteries (e.g., lithium ion secondary batteries) 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 is a metal foil, specifically a copper foil, in this case. The thickness of the negative electrode current collector 24c is preferably 5 μm to 20 μm, and more preferably 6 μm to 10 μm.

[0038] As shown in FIG. 5, in the negative electrode 24, a negative electrode tab 24t protrudes from one end side in the winding axis direction WD toward the outside (upper side in FIG. 5). The negative electrode tabs 24t are provided at a predetermined interval (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. Here, the negative electrode tab 24t is a part of the negative electrode 24. Here, the negative electrode tab 24t is a region where the negative electrode active material layer 24a is not formed and the negative electrode current collector 24c is exposed. However, a part of the negative electrode active material layer 24a may protrude and be attached to the negative electrode tab 24t. In addition, the negative electrode tab 24t may be a member separate from the negative electrode 24.

[0039] Here, each of the negative electrode tabs 24t is trapezoidal. However, the shape and size of the negative electrode tabs 24t can be appropriately adjusted in the same manner as the positive electrode tab 22t. In one embodiment, the length of the negative electrode tab 24t in the width direction (LD direction in FIG. 5) may be 10 mm to 30 mm (for example, 15 mm to 20 mm), and the length of the negative electrode tab 24t in the protruding direction (Z direction in FIG. 5) may be 10 mm to 30 mm (for example, 15 mm to 20 mm). The negative electrode tabs 24t are stacked at one end (upper end in FIG. 5) of the winding axis direction WD of the negative electrode 24 to form a negative electrode tab group 27 (see FIG. 2).

[0040] 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. The width of the negative electrode active material layer 24a refers to the length of the portion having a substantially constant thickness in the winding axis direction WD, and does not include the portion of the negative electrode tab 24t even if a part of the negative electrode active material layer 24a protrudes and adheres to the negative electrode tab 24t. The negative electrode active material layer 24a contains a negative electrode active material capable of reversibly absorbing and releasing charge carriers. The negative electrode active material is preferably, for example, a carbon material such as graphite or a silicon material. When the entire solid content of the negative electrode active material layer 24a is taken as 100% by mass, the negative electrode active material may occupy approximately 80% by mass or more, typically 90% by mass or more, for example 95% by mass or more. The negative electrode active material layer 24a may contain any component other than the negative electrode active material, such as a binder, a conductive material, various additive components, etc. The negative electrode active material layer 24a preferably contains a binder in addition to the negative electrode active material. The binder preferably contains a rubber such as styrene butadiene rubber (SBR) or a cellulose such as carboxymethyl cellulose (CMC). The negative electrode active material layer 24a may contain a carbon material as a conductive material as necessary.

[0041] As shown in FIG. 5 and FIG. 7, the separator 70 is a strip-shaped member. The separator 70 is an insulating sheet having a plurality of fine through-holes through which charge carriers can pass. The width of the separator 70 is greater than the width of the negative electrode active material layer 24a. By interposing the separator 70 between the positive electrode 22 and the negative electrode 24, contact between the positive electrode 22 and the negative electrode 24 can be prevented, and charge carriers (e.g., lithium ions) can be moved between the positive electrode 22 and the negative electrode 24. Although not particularly limited, the thickness of the separator 70 (length in the stacking direction MD; the same applies below) is preferably 3 μm or more, more preferably 5 μm or more. The thickness of the separator 70 is preferably 25 μm or less, more preferably 22 μm or less, and even more preferably 18 μm or less.

[0042] Here, two separators 70 are used for one wound electrode body 20. As in this embodiment, it is preferable that two separators 70, i.e., a first separator 70A and a second separator 70B, are used for one wound electrode body 20. The two separators may have different configurations or may have the same configuration.

[0043] The separator 70 is a member that insulates the positive electrode active material layer 22a of the positive electrode 22 from the negative electrode active material layer 24a of the negative electrode 24. For example, a porous resin sheet made of a polyolefin resin such as polyethylene (PE) or polypropylene (PP) is suitable as the separator 70. A heat resistance layer (HRL) containing an inorganic filler may be provided on the surface of the separator 70. For example, alumina, boehmite, aluminum hydroxide, titania, etc. may be used as the inorganic filler. In addition, an adhesive layer may be provided on the surface of the separator 70. For example, an organic resin, an acrylic resin, an epoxy resin, a styrene butadiene rubber, a silicone rubber, a PVdF, etc. may be used as the adhesive layer.

[0044] Next, the winding mode of the wound electrode body 20 according to this embodiment will be described. Here, FIG. 8 is a schematic diagram showing the cross-sectional configuration of the wound electrode body in FIG. 3. In FIG. 8, hatching of each member is omitted for ease of viewing. As shown in FIG. 8, the wound electrode body 20 is a flat wound electrode body in which a strip-shaped positive electrode 22 and a strip-shaped negative electrode 24 are wound with a strip-shaped separator 70 (first separator 70A, second separator 70B) interposed therebetween. The positive electrode 22 is provided with a plurality of positive electrode tabs 22t. In addition, in a cross-sectional view cut in a direction perpendicular to the winding axis WL of the wound electrode body 20, the positive electrode 22 has a first region A1 located on one side (lower side in FIG. 8) of the winding axis WL of the wound electrode body 20 in a thickness direction (direction X in FIG. 8) from one flat surface 20f1 through the winding axis WL to the other flat surface 20f2, and a second region A2 located on the other side (upper side in FIG. 8) of the winding axis WL in the thickness direction X. In the first region A1, positive electrode tabs 22t are provided in more than 80% of the layers of the positive electrode 22. In the second region A2, there are multiple layers on which positive electrode tabs 22t are formed in the layers from the winding axis WL side to the fifth layer. And, no positive electrode tab 22t is provided in the layers outside the fifth layer from the winding axis WL side. In addition, as shown in FIG. 4, multiple positive electrode tabs 22t are stacked and joined to the positive electrode current collecting part 50. In addition, in Figure 8, 22e indicates the winding end of the positive electrode, 24e indicates the winding end of the negative electrode, 70As indicates the winding start end of the first separator, 70Ae indicates the winding end of the first separator, 70Bs indicates the winding end of the second separator, and 70Be indicates the winding end of the second separator.

[0045] The "layers" in the first region A1 of the positive electrode 22 are counted as the first layer, the second layer, ..., n-th layer from the winding axis WL side (inner side) toward the outermost surface side (outer side) of the wound electrode body 20 in the first region A1. The "layers" in the second region A2 of the positive electrode 22 are counted as the first layer, the second layer, ..., n-th layer from the winding axis WL side (inner side) toward the outermost surface side (outer side) of the wound electrode body 20 in the second region A2. The "layers" in the first region A1 of the negative electrode 24 are counted as the first layer, the second layer, ..., n-th layer from the winding axis WL side (inner side) toward the outermost surface side (outer side) of the wound electrode body 20 in the first region A1. The "layers" in the second region A2 of the negative electrode 24 are counted as the 1st layer, 2nd layer, ... nth layer from the winding axis WL side (inner side) toward the outermost surface side (outer side) of the wound electrode body 20. However, in the vicinity of the winding start end of the electrode, if the length from the winding start end of the electrode to the first folded part (the apex of the first turn part or first curved part) is shorter than a predetermined length, it will not be counted as one layer.

[0046] Here, Fig. 9 is a schematic diagram showing the vicinity 22s of the winding start end of the positive electrode and the vicinity 24s of the winding start end of the negative electrode. Note that in Fig. 9, the separator 70 is omitted for ease of viewing. A straight line X1 in Fig. 9 indicates the first folded portion 24r in the thickness direction X among the multiple negative electrode tabs 24t. a1 The negative electrode tab 24t located closest to 6A1 The first fold of 24r a1 The line X2 passes through the end of the positive electrode tab 22t on the side of the first folded-back portion 22r in the thickness direction X. b1 The positive electrode tab 22t located closest to 5A2 The first fold of 22r b1 In this embodiment, the winding start end 24s of the negative electrode 24 does not exceed the straight line X1 in the thickness direction X (in other words, the first folded-back portion 24r a1 The length from the first folded portion 24r to the winding start end 24s of the negative electrode is a1The length from the first folded portion 22r to the straight line X1 is smaller than the length from the first folded portion 22r to the straight line X2. b1 The length from the first folded portion 22r to the winding start end 22s of the positive electrode is b1 8, the negative electrode tab 24t in the first region A1 is counted as one layer. 1A1 ,24t 2A1 ,24t 3A1 ,24t 4A1 ,24t 5A1 ,24t 6A1 The layers in which the negative electrode tabs 24t are present are counted as the first layer, the second layer, the third layer, the fourth layer, the fifth layer, and the sixth layer, respectively. 1A2 ,24t 2A2 ,24t 3A2 ,24t 4A2 ,24t 5A2 The layers in which the positive electrode tabs 22t are present are counted as the first layer, the second layer, the third layer, the fourth layer, and the fifth layer, respectively. 1A1 ,22t 2A1 ,22t 3A1 ,22t 4A1 ,22t 5A1 ,22t 6A1 The layers in which the positive electrode tabs 22t are present are counted as the first layer, the second layer, the third layer, the fourth layer, the fifth layer, and the sixth layer, respectively. 1A2 ,22t 2A2 ,22t 3A2 ,22t 4A2 ,22t 5A2 The layers in which exist are counted as the first layer, second layer, third layer, fourth layer, and fifth layer, respectively.

[0047] FIG. 10 is an explanatory diagram for explaining the first region A1 and the second region A2 in FIG. 8. Also, FIG. 13 is a diagram corresponding to FIG. 8 in the prior art. As shown in FIGS. 10 and 13, the maximum tab displacement amount G2 (here, the maximum displacement amount G3 of the positive electrode tab group 25 in the width direction (Y direction in FIG. 10) of the wound electrode body 20 is6A1 and positive electrode tab 22t 5A2 The maximum tab misalignment amount G2′ (here, the maximum tab misalignment amount G1′ of the positive electrode tab group 225 of the wound electrode body 220 in the width direction (the Y direction in FIG. 13) of the positive electrode tab 222t 6A1 and positive electrode tab 222t 6A2 10) in the width direction (Y direction in FIG. 10) of the negative electrode tab group 27 of the wound electrode body 20 is increased compared to the joint portion (dashed line frame portion in FIG. 13) between the positive electrode tab group 225 and the positive electrode current collecting portion 50 of the wound electrode body 220. Similarly, on the negative electrode 24 side, the maximum tab misalignment amount G1 (here, the negative electrode tab 24t 6A1 and negative electrode tab 24t 5A2 The maximum tab misalignment amount G1′ (here, the maximum tab misalignment amount G1′ of the negative electrode tab group 227 of the wound electrode body 220 in the width direction (the Y direction in FIG. 13) of the negative electrode tab 224t 7A1 and negative electrode tab 224t 7A2 It can be seen that the amount of tab misalignment in the Y direction of the electrode tab group 25 (a portion enclosed by a dashed line in FIG. 10) is reduced compared to the amount of tab misalignment in the Y direction of the electrode tab group 25 (a portion enclosed by a dashed line in FIG. 13) in the wound electrode body 20. In other words, it can be seen that the joint portion between the negative electrode tab group 27 and the negative electrode current collector 60 in the wound electrode body 220 (a portion enclosed by a dashed line in FIG. 13) is increased compared to the joint portion between the negative electrode tab group 227 and the negative electrode current collector 60 in the wound electrode body 220. Therefore, in the battery 100 disclosed here, the positive electrode tab group 25 (negative electrode tab group 27) and the positive electrode current collector 50 (negative electrode current collector 60) are stably joined compared to the conventional battery, so that the battery 100 can be said to be a battery with suitably improved reliability. Furthermore, in the battery 100 disclosed here, the number of electrode tabs (positive electrode tabs 22t, negative electrode tabs 24t) in the first region A1 and the second region A2 is suitably adjusted, so that an increase in battery resistance can be suitably prevented.

[0048] As shown in FIG. 8, the number of layers (layers) of the positive electrode 22 in the wound electrode body 20 is 12, but is not limited thereto. The number of layers of the positive electrode 22 in the wound electrode body 20 is, for example, 10 or more, and from the viewpoint of obtaining a battery 100 with a higher capacity, it is preferably 20 or more, more preferably 30 or more, and may be, for example, 40 or more. Also, as shown in FIG. 8, the number of layers (layers) of the negative electrode 24 in the wound electrode body 20 is 14, but is not limited thereto. The number of layers of the negative electrode 24 in the wound electrode body 20 is, for example, 10 or more, and from the viewpoint of obtaining a battery 100 with a higher capacity, it is preferably 20 or more, more preferably 30 or more, and may be, for example, 40 or more. The number of layers of the positive electrode 22 and the number of layers of the negative electrode 24 in the wound electrode body 20 may be the same or different.

[0049] As described above, in the first region A1, the positive electrode tabs 22t are provided in 80% or more of the layers of the positive electrode 22. In other words, (the number of layers of the positive electrode 22 on which the positive electrode tabs 22t are formed) / (the total number of layers of the positive electrode 22) is 0.8 or more. With this configuration, the increase in resistance of the battery 100 can be suitably suppressed. Here, from the viewpoint of making it easier to obtain such an effect, (the number of layers of the positive electrode 22 on which the positive electrode tabs 22t are formed) / (the total number of layers of the positive electrode 22) is preferably 0.9 or more, and more preferably 1. As shown in FIG. 8, in this embodiment, the positive electrode tabs 22t are provided in all six layers of the six layers of the positive electrode 22 in the first region A1. That is, (the number of layers of the positive electrode 22 on which the positive electrode tabs 22t are formed) / (the total number of layers of the positive electrode 22) is 1. Also, in the first region A1, the negative electrode tabs 24t are provided in 80% or more of the layers of the negative electrode 24. In other words, (the number of layers of the negative electrode 24 on which the negative electrode tab 24t is formed) / (the total number of layers of the negative electrode 24) is 0.8 or more. With this configuration, the resistance increase of the battery 100 can be suitably suppressed. Here, from the viewpoint of making it easier to obtain such an effect, (the number of layers of the negative electrode 24 on which the negative electrode tab 24t is formed) / (the total number of layers of the negative electrode 24) is preferably 0.9 or more, and more preferably 1. As shown in FIG. 8, in this embodiment, the negative electrode tab 24t is provided in six layers out of the seven layers of the negative electrode 24 in the first region A1. That is, (the number of layers of the negative electrode 24 on which the negative electrode tab 24t is formed) / (the total number of layers of the negative electrode 24) is 0.9. (The number of layers of the positive electrode 22 on which the positive electrode tab 22t is formed) / (the total number of layers of the positive electrode 22) and (the number of layers of the negative electrode 24 on which the negative electrode tab 24t is formed) / (the total number of layers of the negative electrode 24) may be the same or different.

[0050] As described above, in the second region A2, the layers from the winding axis WL side to the fifth layer include a plurality of layers on which the positive electrode tab 22t is formed. Here, the positive electrode tab 22t is formed in all layers from the winding axis WL side to the fifth layer. The positive electrode tab 22t is not provided in layers outside the fifth layer from the winding axis WL side. With this configuration, the positive electrode tab group 25 and the positive electrode current collecting portion 50 can be stably joined. Here, from the viewpoint of making it easier to obtain such an effect, it is preferable that the positive electrode tab 22t is not provided in layers outside the fourth layer from the winding axis WL side, and it is more preferable that the positive electrode tab 22t is not provided in layers outside the second layer from the winding axis WL side. In the second region A2, the positive electrode tab 22t may not be formed in any of the first to fifth layers. In addition, it is preferable that the positive electrode tab 22t is formed in at least one of the first and second layers. It is preferable that the positive electrode tab 22t is formed on the first to third layers. In particular, when the length of the first layer of the positive electrode 22 in the winding direction D1 of the positive electrode 22 is 5 cm or more, it is preferable that the first layer of the positive electrode 22 is also provided with the positive electrode tab 22t.

[0051] In the present embodiment, in the second region A2, the layers from the winding axis WL side to the fifth layer include a plurality of layers on which the negative electrode tab 24t is formed. Here, the negative electrode tab 24t is formed in all layers from the winding axis WL side to the fifth layer. The negative electrode tab 24t is not provided in layers outside the fifth layer from the winding axis WL side. With this configuration, the negative electrode tab group 27 and the negative electrode current collecting portion 60 can be stably joined. Here, from the viewpoint of making it easier to obtain such an effect, it is preferable that the negative electrode tab 24t is not provided in layers outside the fourth layer from the winding axis WL side, and it is more preferable that the negative electrode tab 24t is not provided in layers outside the second layer from the winding axis WL side. In the second region A2, the negative electrode tab 24t may not be formed in any of the first to fifth layers. It is also preferable that the negative electrode tab 24t is formed in at least one of the first and second layers. It is preferable that the negative electrode tab 24t is formed on the first to third layers. In particular, when the length of the first layer of the negative electrode 24 in the winding direction D1 of the negative electrode 24 is 5 cm or more, it is preferable that the first layer of the negative electrode 24 is also provided with the negative electrode tab 24t.

[0052] The maximum tab shift amount G2 in the width direction of the positive electrode tab group 25 is not particularly limited as long as the effect of the technology disclosed herein is exerted, but is, for example, 0.01 mm or more, and from the viewpoint of making it easy to check whether there is a broken positive electrode tab 22t, it is preferably 0.05 mm or more, and more preferably 0.1 mm or more. The upper limit of the maximum tab shift amount G2 is, for example, 10 mm or less, and from the viewpoint of more stably joining the positive electrode tab group 25 and the positive electrode current collecting part 50, it is preferably 5 mm or less, and more preferably 2 mm or less. The maximum tab shift amount G1 in the width direction of the negative electrode tab group 25 is not particularly limited as long as the effect of the technology disclosed herein is exerted, but is, for example, 0.01 mm or more, and from the viewpoint of making it easy to check whether there is a broken negative electrode tab 24t, it is preferably 0.05 mm or more, and more preferably 0.1 mm or more. The upper limit of the maximum tab displacement amount G1 is, for example, 10 mm or less, and from the viewpoint of more stably joining the negative electrode tab group 27 and the negative electrode current collecting portion 60, it is preferably 5 mm or less, and more preferably 2 mm or less. However, it is not intended to be limited to these values. The maximum tab displacement amounts G1 and G2 may be the same or different.

[0053] As shown in FIG. 9, in this embodiment, the first region A1 includes the winding start end 24s of the negative electrode. In addition, the winding start end 22s of the positive electrode starting from the second region A2 is arranged in the range from the winding start end 24s of the negative electrode to the first first R portion R1 (in other words, to the end R11 of the first first R portion). With this configuration, the surface pressure in the wound electrode body 20 tends to be constant, and the precipitation resistance of Li (lithium) can be suitably improved. Here, the length from the winding start end 24s of the negative electrode in the first region A1 to the end R11 of the first R portion is preferably 1 mm to 10 mm, more preferably 4.5 mm to 7.5 mm. In addition, the winding start end 22s of the positive electrode in the second region A2 is preferably 0.1 mm to 10 mm from the end R12 of the first R portion R1, more preferably 1.5 mm to 4.5 mm. However, it is not intended to be limited thereto.

[0054] As shown in Fig. 8, in this embodiment, a stop tape 200 is disposed at the winding end of the separator (here, the winding end 70Ae of the first separator). As the stop tape 200, any stop tape used in this type of battery (for example, a resin stop tape) can be used without any particular restrictions. By providing the stop tape 200 in this manner, the winding end of the separator can be suitably fixed to the outermost surface of the wound electrode body 20, which is preferable.

[0055] <Battery manufacturing method> Next, an example of a method for manufacturing the battery 100 will be described. In manufacturing the wound electrode body 20, first, the first separator 70A, the positive electrode 22, the second separator 70B, and the negative electrode 24 are prepared. Next, each member is wound by a winding roller. After that, the wound body is pressed with a predetermined pressure, and a winding stop tape 200 is applied to the winding end 70Ae of the first separator, thereby obtaining the wound electrode body 20. Two such wound electrode bodies 20 are prepared, and these are inserted into the exterior body 12 in a state in which the electrode tab group is joined to the electrode current collector attached to the sealing plate 14, and the exterior body 12 and the sealing plate 14 are joined (welded) to construct the battery case 10. Then, an electrolyte is injected into the inside of the battery case 10 from the liquid injection hole 15 of the sealing plate 14, and the liquid injection hole 15 is closed with the sealing member 16. In this manner, the battery 100 can be manufactured.

[0056] Battery 100 can be used for various purposes, but can be suitably used, for example, as a power source (driving power source) for motors mounted on vehicles such as passenger cars and trucks, ships, and heavy machinery. The type of vehicle is not particularly limited, but examples include plug-in hybrid electric vehicles (PHEVs), hybrid electric vehicles (HEVs), battery electric vehicles (BEVs), and the like.

[0057] Although several embodiments of the present disclosure have been described above, the above embodiments are merely examples. The present disclosure can be implemented in various other forms. The present disclosure 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. In addition, if the technical feature is not described as essential, it is also possible to delete it as appropriate.

[0058] For example, in the above embodiment, the first region A1 in which the positive electrode tab 22t is formed and the first region A1 in which the negative electrode tab 24t is formed are on the same side, and the second region A2 in which the positive electrode tab 22t is formed and the second region A2 in which the negative electrode tab 24t is formed are on the same side, but this is not limited to the above. Here, FIG. 12 is a view corresponding to FIG. 8 according to another embodiment. As shown in FIG. 12, in another embodiment, the first region in which the positive electrode tab 22t is formed and the second region in which the negative electrode tab 24t is formed may be on the same side, and the second region in which the positive electrode tab 22t is formed and the first region in which the negative electrode tab 24t is formed may be on the same side.

[0059] For example, in the above embodiment, the region including the winding start end 24s of the negative electrode (in other words, the region from the winding start end 24s of the negative electrode to the first folded-back portion 24r a1 The negative electrode winding start end 24s (region up to the winding start end 24s) is located on the first region A1 side, but is not limited to this. In other embodiments, the region including the negative electrode winding start end 24s may be located on the second region A2 side.

[0060] For example, in the above embodiment, the positive electrode tab 22t and the negative electrode tab 24t are provided at the end on the same side in the winding axis direction WD, but this is not limited thereto. The technology disclosed herein can also be applied to a battery including a wound electrode body in which the positive electrode tab and the negative electrode tab are provided at the end on different sides in the winding axis direction WD.

[0061] For example, while notches are present in the first tabs of positive electrode 22 and negative electrode 24 in the above embodiment, such notches may not be present in the batteries disclosed herein.

[0062] For example, in the above embodiment, a stop tape is applied to the end of the separator located on the outermost surface of the wound electrode body, but this is not limited thereto. The technology disclosed herein can also be applied to a battery that does not have a stop tape. In such a case, it is preferable that an adhesive layer is formed on the inner surface near the end of the separator located on the outermost surface of the wound electrode body. This allows the end of the separator to be suitably fixed to the wound electrode body.

[0063] As described above, specific aspects of the technology disclosed herein include those described in the following items. Item 1: A battery including a flat wound electrode body in which a band-shaped first electrode and a band-shaped second electrode are wound with a band-shaped separator interposed therebetween, the first electrode being provided with a plurality of first electrode tabs, the first electrode having a first region located on one side of the winding axis of the wound electrode body in a thickness direction from one flat surface through the winding axis to the other flat surface in a cross-sectional view taken in a direction perpendicular to the winding axis of the wound electrode body, and a second region located on the other side of the winding axis in the thickness direction, the first electrode tabs being provided on 80% or more of the layers of the first electrode in the first region, the layers from the winding axis side to the fifth layer in the second region include a plurality of layers on which the first electrode tabs are formed, and the first electrode tabs are not provided on layers outer than the fifth layer from the winding axis side, and the plurality of first electrode tabs are stacked and joined to a current collecting member. Item 2: The battery according to item 1, wherein the stacked first electrode tabs have a maximum tab misalignment amount of 0.05 mm to 5 mm in the width direction of the first electrode tabs. Item 3: The battery described in item 1 or 2, wherein the first region includes a winding start end of the second electrode, and the winding start end of the first electrode starting from the second region is disposed in a range from the winding start end of the second electrode to a first R portion. Item 4: The battery according to any one of items 1 to 3, wherein the first electrode is a positive electrode, and the first electrode tab is a positive electrode tab. Item 5: The battery according to any one of items 1 to 4, wherein the stacked first electrode tabs are joined to the current collecting member in a curved state. Item 6: The battery according to any one of items 1 to 5, further comprising a battery case that houses the wound electrode body, the battery case including an exterior body including a bottom wall, a pair of first side walls, a pair of second side walls, and an opening, and a sealing plate that seals the opening, the wound electrode body being disposed in the battery case such that the winding axis of the wound electrode body is perpendicular to the bottom wall. Item 7: The battery according to any one of items 1 to 6, wherein the length of the wound electrode body in a direction perpendicular to the thickness direction is three times or more the length of the wound electrode body along the winding axis direction. Item 8: The battery according to any one of items 1 to 7, wherein the wound electrode body has a thickness of 10 mm or more. Item 9: The battery according to any one of items 1 to 8, wherein the first tabs of the first electrode and the second electrode each have a notch formed therein. [Explanation of symbols]

[0064] 10 Battery case 12 Exterior body 12a Bottom wall 12b Long side wall 12c short side wall 12h opening 14 Sealing plate 15 Liquid injection hole 16 Sealing member 17 Gas exhaust valve 18 Terminal extraction hole 20 Wound electrode body 20f flat area 20r curved section 22 Positive electrode 22a Cathode active material layer 22c Positive electrode current collector 22p positive electrode protective layer 22t Positive electrode tab 24 Negative electrode 24a Negative electrode active material layer 24c Negative electrode current collector 24t negative electrode tab 25 Positive electrode tab group 27 Negative electrode tab group 29 Electrode holder 30 Positive terminal 30c bottom end 32 Positive electrode external conductive member 34 Heat-resistant layer 40 Negative terminal 40c bottom end 42 Negative electrode external conductive member 50 Positive electrode current collector 60 Negative electrode current collector 70 Separator 70A First Separator 70B Second separator 90 Gasket 92 External insulating material 94 Internal insulation material 100 batteries 200 Winding tape LD Longitudinal U upward WL Winding shaft Y Longitudinal direction Z vertical direction

Claims

1. A battery including a flat wound electrode body in which a strip-shaped first electrode and a strip-shaped second electrode are wound with a strip-shaped separator interposed therebetween, The first electrode is provided with a plurality of first electrode tabs; The first electrode is In a cross-sectional view taken in a direction perpendicular to the winding axis of the wound electrode body, the wound electrode body has a first region located on one side of the winding axis of the wound electrode body in a thickness direction from one flat surface through the winding axis to the other flat surface, and a second region located on the other side of the winding axis in the thickness direction, In the first region, the first electrode tabs are provided on 80% or more of the layers of the first electrode; In the second region, the layers from the winding axis side to the fifth layer include a plurality of layers on which the first electrode tab is formed, the first electrode tab is not provided on any layer outside the fifth layer from the winding axis side, A battery, wherein a plurality of the first electrode tabs are stacked and joined to a current collecting member.

2. The stacked first electrode tabs include The battery according to claim 1 , wherein a maximum amount of tab misalignment in a width direction of the first electrode tab is 0.05 mm to 5 mm.

3. the first region includes a winding start end of the second electrode, 3 . The battery according to claim 1 , wherein the winding start end of the first electrode, which starts from the second region, is disposed in a range from the winding start end of the second electrode to a first R portion.

4. 3. The battery of claim 1, wherein the first electrode is a positive electrode and the first electrode tab is a positive electrode tab.

5. The battery according to claim 1 , wherein the stacked first electrode tabs are joined to the current collecting member in a curved state.

6. a battery case that houses the wound electrode body, the battery case includes an exterior body including a bottom wall, a pair of first side walls, a pair of second side walls, and an opening, and a sealing plate that seals the opening, The battery according to claim 1 , wherein the wound electrode body is disposed in the battery case such that the winding axis of the wound electrode body is perpendicular to the bottom wall.

7. The battery according to claim 1 , wherein a length of the wound electrode body in a direction perpendicular to the thickness direction is three times or more larger than a length of the wound electrode body along a winding axis direction.

8. The battery according to claim 1 or 2, wherein the wound electrode body has a thickness of 10 mm or more.

9. The battery according to claim 1 , wherein the first tabs of the first electrode and the second electrode each have a notch formed therein.

10. A battery as described in claim 1 or 2, wherein the number of layers of the first electrode is 20 or more.

Images