JP2017004892A - Power storage element, and manufacturing method of power storage element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage element which suppresses capacity deterioration, and a manufacturing method of the power storage element.SOLUTION: The present invention relates to a power storage element and a manufacturing method of the power storage element. The power storage element comprises an electrode body including a wound body 22 in which a positive electrode and a negative electrode are wound while being overlapped. The negative electrode includes a sheet-like conductive part 241 and an active material layer 242 that overlaps the conductive part, and is positioned in an innermost periphery and an outermost periphery of the wound body 22. A terminal part 245 of the negative electrode at an innermost periphery side and a terminal part 246 at an outermost periphery side extend from corresponding edges 235A and 236A of the positive electrode in a winding direction. In the terminal parts 245 and 246 of the negative electrode extending from the corresponding edges and on a surface of the conductive part 241 directed towards a side of the corresponding edges, an active material layer 242A that is thinner than the active material layer 242 in the other portion of the negative electrode is included, or any active material layer is not included.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a power storage element including an electrode body wound in a state where a positive electrode and a negative electrode overlap each other, and a method for manufacturing the power storage element.

  Conventionally, a secondary battery including an electrode body in which a positive electrode sheet and a negative electrode sheet are wound in a laminated state is known (see Patent Document 1). In this secondary battery, the positive electrode sheet may have a coated part in which an electrode active material is applied on both sides in the thickness direction of the sheet and an uncoated part in which the electrode active material is not applied. Yes. These coated portions and uncoated portions are aligned in the width direction of the positive electrode sheet. Moreover, the said negative electrode sheet has a coating part and an uncoated part similarly to the said positive electrode sheet.

  In the secondary battery described above, in order to secure battery capacity, the negative electrode sheet is usually longer than the positive electrode sheet, and when the positive electrode sheet and the negative electrode sheet are wound together with the positive electrode sheet, It is located on the innermost periphery and the outermost periphery. And the innermost peripheral end and the outermost peripheral end in the longitudinal direction of the negative electrode sheet extend so as to protrude from the corresponding edge of the positive electrode sheet. That is, in the electrode body, the end in the longitudinal direction of the negative electrode sheet does not face the positive electrode sheet.

  In such a secondary battery (for example, a lithium secondary battery), the potential of the other part (part facing the positive electrode sheet) except for the end portion of the negative electrode sheet decreases during charging. Since the potential of the end portion is maintained, a potential difference is generated between the end portion (a portion not facing the positive electrode sheet) and the other portion. For this reason, in the negative electrode, the lithium ions in the other part move to the end part, thereby reducing the number of lithium ions in the other part contributing to charging and discharging. This reduction in the number of lithium ions becomes remarkable by repeated charge and discharge, and as a result, the capacity of the secondary battery is greatly reduced, that is, capacity deterioration occurs in the secondary battery.

Japanese Patent Laying-Open No. 2015-56257

  Therefore, an object of the present invention is to provide a power storage element in which capacity deterioration is suppressed and a method for manufacturing the power storage element.

The electricity storage device according to the present invention is:
An electrode body having a wound body wound in a state where the belt-like positive electrode and the negative electrode overlap with each other,
The negative electrode has a sheet-like conductive portion and an active material layer overlapping the conductive portion, and is located on the innermost periphery and the outermost periphery of the wound body,
At least one of the innermost end and the outermost end in the winding direction of the negative electrode extends in the winding direction from the corresponding edge of the positive electrode,
The end portion of the negative electrode extending from the corresponding edge has the active material layer thinner than the active material layer of the other part of the negative electrode on the surface of the conductive portion facing the corresponding edge side. Or, it does not have the active material layer.

  According to such a configuration, the active material layer at the end of the negative electrode (the portion extending from the corresponding edge of the positive electrode, that is, the portion not facing the positive electrode) is thin or has no active material layer. Even when a potential difference occurs between the end and the other part (part facing the positive electrode) during discharge, the number of ions that can move from the other part to the end is suppressed. Thus, the capacity deterioration of the electricity storage element due to the movement of ions in the negative electrode can be suppressed.

  Further, when the negative electrode has an active material layer thinner than the active material layer of the other part on the surface of the end portion facing the corresponding edge of the conductive portion, the active material is formed on the surface. Since the rigidity of the end portion of the negative electrode is higher than in the case where there is no layer, it is possible to suppress a deviation from a planned position or a short circuit due to the end portion being bent or the like.

Further, in the power storage element,
Ends extending from the corresponding edge are provided at the innermost peripheral portion and the outermost peripheral portion of the negative electrode,
The negative electrode is a range on a surface facing the inner side of the conductive portion of the innermost peripheral portion until reaching a position sandwiched by the positive electrode from the innermost peripheral edge in the winding direction. And the range of the outermost peripheral portion on the surface facing the outer side of the conductive portion until reaching the position sandwiched by the positive electrode from the outermost peripheral edge in the winding direction. In the range, the active material layer may be thinner than the active material layer of the other part, or the active material layer may not be provided.

  According to such a configuration, in the negative electrode, the conductive portion of the innermost portion of the conductive portion on the inner side (winding center side) of the conductive portion (the portion not facing the positive electrode) and the outermost portion of the conductive portion. The active material layer having a thinner active material layer than the active material layer of the portion facing the positive electrode on the surface (the portion not facing the positive electrode) facing the outside (the side opposite to the winding center) in Therefore, during charging / discharging of the electricity storage device, the potential difference between the innermost peripheral portion and the outermost peripheral portion of the negative electrode and the portions other than the innermost peripheral portion and the outermost peripheral portion are excluded. Even if this occurs, the movement of ions to the innermost peripheral portion and the outermost peripheral portion is suppressed. Thereby, the capacity deterioration of the electrical storage element resulting from the movement of the ions is more effectively suppressed.

Further, in the power storage element,
The end portions of the negative electrode extending from the corresponding end portions of the positive electrode may have the active material layers thinner than the active material layers of other portions of the negative electrode on both surfaces of the conductive portion.

  According to such a configuration, since the active material layers thinner than the active material layers of the other parts are respectively provided on both surfaces of the conductive portion at the end portion of the negative electrode, or when there is no active material layer on the both surfaces, Compared with the case where the thin active material layer is provided only on one surface, the end of the negative electrode has higher rigidity, thereby more reliably suppressing deviation from a planned position and short circuit due to bending of the end. Can do.

In addition, a method for manufacturing a power storage device according to the present invention includes:
A thin-walled portion provided in the middle of the longitudinal direction in a strip-shaped negative electrode having a sheet-like conductive portion and an active material layer overlapping with the conductive portion, and the other portion of the negative electrode on the surface of the conductive portion Cutting a thin-walled portion having an active material layer thinner than the active material layer or not having the active material layer along the short direction of the negative electrode;
The state in which the thin-walled portion constituting the longitudinal end of the negative electrode extends in the longitudinal direction from at least one of the one edge and the other edge in the longitudinal direction of the belt-like positive electrode after the cutting And the positive electrode and the negative electrode are stacked, and the stacked positive electrode and negative electrode are wound from the one edge side.

  According to this configuration, it is possible to obtain an energy storage device in which capacity deterioration due to ion movement from a portion facing the positive electrode to a portion not facing the negative electrode in the negative electrode during charge / discharge is suppressed. Specifically, it is as follows.

  According to the above configuration, at least one of the innermost circumferential end and the outermost circumferential end in the winding direction of the negative electrode extends in the winding direction from the corresponding edge of the positive electrode, and the negative electrode An electrode having an active material layer thinner than an active material layer of the other part of the negative electrode or an active material layer not provided on the surface facing the corresponding edge side of the conductive part of the end portion extending from the corresponding edge A power storage element having a body is obtained. In this power storage element, since the active material layer at the end of the negative electrode (the part extending from the corresponding edge of the positive electrode, that is, the part not facing the positive electrode) is thin or has no active material layer in the electrode body, During charge / discharge of the element, even if a potential difference occurs between the end and the other part (part facing the positive electrode), the number of ions that can move from the other part to the end is suppressed. It is done. Thereby, capacity deterioration of the electricity storage element due to the movement of the ions is suppressed.

Further, in the method for manufacturing the electricity storage element,
The negative electrode may have an uncoated portion of the active material layer that is continuous in the longitudinal direction.

  When a negative electrode having an uncovered portion continuous in the longitudinal direction is cut in the width direction, the entire thickness of the negative electrode changes at the boundary between the portion where the active material layer is formed and the non-covered portion. In the vicinity of the boundary between the portion where the non-covered portion is formed and the burrs and chips (specifically, the burrs and chips caused by the difference between the stress applied to the portion where the active material layer is formed and the stress applied to the non-covered portions). Powder) is likely to occur. However, according to the above configuration, in order to cut the thin-walled portion that is reduced by thinning or eliminating the active material layer, the change in the overall thickness of the negative electrode at the boundary between the non-covered portion and the portion other than the non-covered portion is cut. It is possible to suppress the generation of the burrs and chips when the process is performed. That is, if the active material layer is thick, the change in the entire thickness of the negative electrode at the boundary between the portion where the active material layer is formed and the non-covered portion is large. However, by suppressing the thickness dimension of the active material layer at the cutting site or eliminating the active material layer as described above, it is possible to suppress the generation of burrs and chips in the conductive portion during the cutting.

in this case,
When the active material layer of the negative electrode contains a component having a Vickers hardness greater than that of the conductive part, the effect of suppressing generation of burrs and chips in the conductive part when the negative electrode is cut becomes more remarkable.

  That is, if the active material layer contains a component having a Vickers hardness greater than that of the conductive portion, the conductive portion is pushed by the component when the negative electrode is cut, so that burrs and chips are more easily generated. By suppressing the thickness, the generation of burrs and chips in the conductive part at the time of cutting can be effectively suppressed even if the active material layer contains the component.

  As described above, according to the present invention, it is possible to provide a power storage element in which capacity deterioration is suppressed and a method for manufacturing the power storage element.

FIG. 1 is a perspective view of a power storage device according to this embodiment. 2 is a cross-sectional view taken along the line II-II in FIG. FIG. 3 is an exploded perspective view of the power storage element. FIG. 4 is a perspective view showing a configuration of an electrode body of the electricity storage element. FIG. 5 is a cross-sectional view of the positive electrode constituting the electrode body. FIG. 6 is a cross-sectional view of the negative electrode constituting the electrode body. FIG. 7 is a schematic diagram for explaining a configuration of a wound body constituting the electrode body and a positive electrode and a negative electrode constituting the wound body. FIG. 8 is a perspective view of a current collector of the electricity storage element. FIG. 9 is a perspective view of a pair of clip members in the power storage element. FIG. 10 is a perspective view of the pair of clip members. 11 is a cross-sectional view taken along the line XI-XI in FIG. FIG. 12 is a cross-sectional view for explaining the negative electrode before being cut into a predetermined length. FIG. 13 is a diagram illustrating a positional relationship between the positive electrode and the negative electrode in a stacked state before winding. FIG. 14 is a flowchart of a method for manufacturing the power storage element. FIG. 15 is a cross-sectional view for explaining a negative electrode before being cut into a predetermined length in another embodiment. FIG. 16 is a perspective view of a power storage device including the power storage element.

  Hereinafter, an embodiment of a power storage device according to the present invention will be described with reference to FIGS. Examples of the power storage element include a primary battery, a secondary battery, and a capacitor. In the present embodiment, a chargeable / dischargeable secondary battery will be described as an example of a power storage element. In addition, the name of each component (each component) of this embodiment is a thing in this embodiment, and may differ from the name of each component (each component) in background art.

  The electricity storage device of this embodiment is a nonaqueous electrolyte secondary battery. More specifically, the power storage element is a lithium ion secondary battery that utilizes electron transfer that occurs as lithium ions move. This type of power storage element supplies electrical energy. One or a plurality of power storage elements are used. Specifically, the storage element is used singly when the required output and the required voltage are small. On the other hand, when at least one of a required output and a required voltage is large, the power storage element is used in a power storage device in combination with another power storage element. In the power storage device, a power storage element used in the power storage device supplies electric energy.

  As shown in FIGS. 1 to 4, the power storage element includes an electrode body 2 having a wound body 22 wound in a state where a belt-like positive electrode 23 and a negative electrode 24 overlap each other. The power storage device 1 of the present embodiment also includes a case 3 that houses the electrode body 2, an external terminal 4 that is disposed outside the case 3, and a current collector 5 that electrically connects the electrode body 2 and the external terminal 4. Have.

  The electrode body 2 is a wound body 22 wound in a state where the core 21, the positive electrode 23, and the negative electrode 24 are insulated from each other, and is wound around (arranged) around the core 21. And a body 22. In the electrode body 2, the lithium ion moves between the positive electrode 23 and the negative electrode 24, whereby the electricity storage device 1 is charged / discharged.

  The winding core 21 is usually formed of an insulating material. The winding core 21 has a cylindrical shape. The core 21 of the present embodiment has a flat cylindrical shape. The winding core 21 is formed by winding a sheet having flexibility or thermoplasticity.

  The said sheet | seat is formed with a synthetic resin and has tolerance with respect to electrolyte solution. The sheet is made of, for example, polypropylene (PP), polyethylene (PE), polyphenylene sulfide (PPS), or polyethylene terephthalate (PET). The thickness of the sheet is, for example, 50 μm to 200 μm.

  The wound body 22 is formed by being wound around the core 21 in a state where the positive electrode 23 and the negative electrode 24 are laminated (overlapped).

  As illustrated in FIGS. 4 and 5, the positive electrode 23 includes a sheet-like conductive portion 231 and a positive electrode active material layer 232 that overlaps the conductive portion 231. In the positive electrode 23 of the present embodiment, the conductive portion 231 is a strip-shaped metal foil, and the positive electrode active material layer 232 is formed (laminated) on both surfaces of the metal foil 231. This metal foil 231 is, for example, an aluminum foil. The positive electrode 23 has an uncovered portion of the positive electrode active material layer 232 (that is, a portion not having the positive electrode active material layer 232) 233 at one edge portion in the width direction, which is the short side direction of the belt shape. The uncovered portion 233 extends continuously in the longitudinal direction of the positive electrode 23. In FIG. 5, the thicknesses of the metal foil 231 and the positive electrode active material layer 232 are exaggerated. Hereinafter, a portion where the positive electrode active material layer 232 is formed in the positive electrode 23 (that is, a portion having the positive electrode active material layer 232) is referred to as a covering portion 234.

  The positive electrode active material layer includes a positive electrode active material and a binder.

The positive electrode active material is, for example, a lithium metal oxide. Specifically, the positive electrode active material is, for example, _a composite oxide (Li _a Co _y O ₂ , Li _a Ni _x ) represented by Li _a Me _b O _c (Me represents one or more transition metals). O ₂ , Li _a Mn _z O ₄ , Li _a Ni _x Co _y Mn _z O _2, etc.), Li _a Me _b (XO _c ) _d (Me represents one or more transition metals, and X represents, for example, P , Si, B, a polyanion compounds represented by the representative of the _{V) (Li a Fe b PO} 4, Li a Mn b PO 4, Li a Mn b SiO 4, Li a Co b PO 4 F , etc.). The positive electrode active material of this embodiment is LiNi _1/3 Co _1/3 Mn _1/3 O ₂ .

  Examples of the binder used in the positive electrode active material layer include polyvinylidene fluoride (PVdF), a copolymer of ethylene and vinyl alcohol, polymethyl methacrylate, polyethylene oxide, polypropylene oxide, polyvinyl alcohol, polyacrylic acid, and polymethacrylic acid. Acid, styrene butadiene rubber (SBR). The binder of this embodiment is polyvinylidene fluoride.

  The positive electrode active material layer may further include a conductive additive such as ketjen black (registered trademark), acetylene black, or graphite. The positive electrode active material layer of this embodiment has acetylene black as a conductive additive.

  As illustrated in FIGS. 4, 6, and 7, the negative electrode 24 includes a sheet-like conductive portion 241 and a negative electrode active material layer (active material layer) 242 that overlaps the conductive portion 241. The negative electrode 24 is located on the innermost periphery and the outermost periphery of the wound body 22. That is, the negative electrode 24 is longer than the positive electrode 23. At least one of the innermost peripheral end 245 and the outermost peripheral end 246 in the winding direction of the negative electrode 24 is longer than the corresponding edges (longitudinal edges) 235A, 236A of the positive electrode 23 in the winding direction. It extends. An end 245 on the innermost peripheral side of the negative electrode 24 of the present embodiment is closer to the winding direction than an end 235A on the innermost peripheral side of the positive electrode 23 located on the outer side of the wound body 22 (on the side opposite to the core 21). The outermost peripheral end 246 extends from the outermost peripheral edge (longitudinal edge) 236A of the positive electrode 23 located on the inner side (winding core 21 side) of the wound body 22. It extends in the turning direction (extrudes). That is, the end 245 extending from the innermost peripheral edge 235 </ b> A of the positive electrode 23 in the negative electrode 24 is provided at the innermost peripheral portion of the negative electrode 24, and the outermost peripheral edge 236 </ b> A of the positive electrode 23 in the negative electrode 24. The extended end 246 is provided at the outermost peripheral portion of the negative electrode 24. In FIG. 6, the thicknesses of the conductive portion 241 and the negative electrode active material layer 242 are exaggerated.

  In the negative electrode 24 of the present embodiment, the conductive portion 241 is a strip-shaped metal foil, and the negative electrode active material layer 242 is formed (laminated) on both surfaces of the metal foil 241. This metal foil 241 is, for example, a copper foil. The negative electrode 24 has a non-covered portion (that is, a negative electrode active material layer) of the negative electrode active material layer 242 at the other edge in the width direction that is the short side direction of the band shape (on the side opposite to the non-covered portion 233 of the positive electrode 23) A portion not having 242) 243. The uncovered portion 243 extends continuously in the longitudinal direction of the negative electrode 24. The width of the covering portion 244 (the portion having the negative electrode active material layer 242) of the negative electrode 24 is larger than the width of the covering portion 234 of the positive electrode 23.

  The end portions 245 and 246 of the negative electrode 24 are formed on the surface of the metal foil 241 facing the corresponding end edges 235A and 236A of the positive electrode 23, and are thinner than the negative electrode active material layer 242 in other parts of the negative electrode 24 ( (Hereinafter also referred to as “thin layer portion”) 242A. That is, the innermost peripheral end 245 of the negative electrode 24 of the present embodiment has a thin layer portion 242A in a portion facing outward (specifically, on the outer surface of the metal foil 241), and the outermost peripheral side. The end portion 246 has a thin layer portion 242A at a portion facing inward (specifically, on a surface facing the inner side of the metal foil 241). In FIG. 7, the thicknesses of the metal foils 231 and 241, the positive electrode active material layer 232, the negative electrode active material layer 242, and the thin layer portion 242 </ b> A are exaggerated.

  The negative electrode 24 is a range on the inner-facing surface of the metal foil 241 at the innermost peripheral portion, and is sandwiched between the innermost peripheral edge 245A in the winding direction and the positive electrode 23 by the wound body 22. The thin layer portion 242A is provided in a range until reaching the position. Further, the negative electrode 24 is a range on the outer-facing surface of the metal foil 241 at the innermost peripheral portion, and is sandwiched between the outer peripheral edge 246A in the winding direction and the positive electrode 23 in the wound body 22. The thin layer portion 242A is provided in a range until reaching the position.

  In the wound body 22 of the present embodiment, the innermost end 245 of the negative electrode 24 extends slightly in the winding direction from the corresponding edge 235 </ b> A of the positive electrode 23 on the surface facing the outside of the metal foil 241. A thin layer portion 242A is provided from the position where it protrudes (extends) to the end edge 245A. Further, the edge from the position slightly extending in the winding direction from the corresponding edge 236A of the positive electrode 23 on the surface facing the inner side of the metal foil 241 of the end 246 on the outermost peripheral side of the negative electrode 24 Thin layer portions 242A are provided up to 246A.

  The negative electrode 24 may have a configuration without the thin layer portion 242A, that is, a configuration in which the metal foil 241 at the portion of the negative electrode 24 is not covered by either the negative electrode active material layer 242 or the thin layer portion 242A.

  The negative electrode active material layer 242 includes a negative electrode active material and a binder. The negative electrode active material layer 242 of this embodiment includes a component having a Vickers hardness greater than that of the metal foil 241.

  The negative electrode active material causes an alloying reaction with, for example, carbon materials such as graphite, non-graphitizable carbon (hard carbon), and graphitizable carbon, or lithium ions such as silicon (Si) and tin (Sn). Material. The negative electrode active material of this embodiment is non-graphitizable carbon.

  The binder used for the negative electrode active material layer is the same as the binder used for the positive electrode active material layer. The binder of this embodiment is polyvinylidene fluoride.

  The negative electrode active material layer may further include a conductive additive such as ketjen black (registered trademark), acetylene black, or graphite. The negative electrode active material layer of this embodiment does not have a conductive additive.

  As shown in FIG. 4, in the wound body 22 of the present embodiment, the positive electrode 23 and the negative electrode 24 configured as described above are wound in a state where they are insulated by a separator 25. That is, in the wound body 22, the positive electrode 23, the negative electrode 24, and the separator 25 are wound in a stacked state. The separator 25 is an insulating member. The separator 25 is disposed between the positive electrode 23 and the negative electrode 24. Thereby, in the electrode body 2 (specifically, the wound body 22), the positive electrode 23 and the negative electrode 24 are insulated from each other. The separator 25 holds the electrolytic solution in the case 3. Thereby, at the time of charging / discharging of the electrical storage element 1, lithium ion moves between the positive electrode 23 and the negative electrode 24 which are laminated | stacked alternately on both sides of the separator 25. FIG.

The separator 25 has a strip shape. Separator 25 is constituted by porous films, such as polyethylene, polypropylene, cellulose, polyamide, for example. The separator 25 is formed by providing an inorganic layer containing inorganic particles such as SiO ₂ particles, Al ₂ O ₃ particles, boehmite (alumina hydrate) on a substrate formed of a porous film. Also good. The separator 25 of the present embodiment is made of polyethylene, for example. The width of the separator (the dimension of the strip shape in the short direction) is slightly larger than the width of the covering portion 244 of the negative electrode 24. The separator 25 is disposed between the positive electrode 23 and the negative electrode 24 that are overlapped with each other so that the covering portions 234 and 244 overlap each other in the width direction. At this time, the non-covered portion 233 of the positive electrode 23 and the non-covered portion 243 of the negative electrode 24 do not overlap. That is, the non-covered portion 233 of the positive electrode 23 protrudes in the width direction from the region where the positive electrode 23 and the negative electrode 24 overlap, and the non-covered portion 243 of the negative electrode 24 extends from the region where the positive electrode 23 and the negative electrode 24 overlap in the width direction ( It protrudes in the direction opposite to the protruding direction of the non-covered portion 233 of the positive electrode 23. The wound body 22 is formed by winding the stacked positive electrode 23, negative electrode 24, and separator 25. The portion where only the uncovered portion 233 of the positive electrode 23 or the uncovered portion 243 of the negative electrode 24 is stacked constitutes the uncoated stacked portion 26 in the electrode body 2.

  The uncoated laminated portion 26 is a portion that is electrically connected to the current collector 5 in the electrode body 2. As shown in FIGS. 3 and 4, the uncoated laminated portion 26 of the present embodiment has two portions sandwiching the hollow portion 27 in the winding center direction view of the wound positive electrode 23, negative electrode 24, and separator 25. It is divided into parts (divided uncoated laminated parts) 261.

  The uncoated laminated portion 26 configured as described above is formed on each electrode of the electrode body 2. That is, the uncoated laminated portion 26 in which only the uncoated portion 233 of the positive electrode 23 is laminated constitutes the uncoated laminated portion of the positive electrode in the electrode body 2, and the uncoated laminated portion in which only the uncoated portion 243 of the negative electrode 24 is laminated. 26 constitutes an uncoated laminated portion of the negative electrode in the electrode body 2.

  Returning to FIGS. 1 to 3, the case 3 includes a case main body 31 having an opening and a lid plate 32 that closes (closes) the opening of the case main body 31. The case 3 houses the electrolytic solution in the internal space 33 together with the electrode body 2 and the current collector 5. Case 3 is formed of a metal having resistance to the electrolytic solution. The case 3 of the present embodiment is formed of an aluminum metal material such as aluminum or an aluminum alloy, for example. The case 3 may be formed of a metal material such as stainless steel and nickel, or a composite material obtained by bonding a resin such as nylon to aluminum.

The electrolytic solution is a non-aqueous electrolytic solution. The electrolytic solution is obtained by dissolving an electrolyte salt in an organic solvent. Examples of the organic solvent include cyclic carbonates such as propylene carbonate and ethylene carbonate, and chain carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. The electrolyte salt is LiClO ₄ , LiBF ₄ , LiPF ₆ or the like. The electrolyte solution of this embodiment is prepared by mixing 1 mol / L LiPF ₆ in a mixed solvent in which propylene carbonate, dimethyl carbonate, and ethyl methyl carbonate are adjusted at a ratio of propylene carbonate: dimethyl carbonate: ethyl methyl carbonate = 3: 2: 5. Is dissolved.

  The case 3 is formed by joining the opening peripheral edge 34 of the case main body 31 and the peripheral edge of the cover plate 32 in an overlapped state. The case 3 has an internal space 33 defined by the case main body 31 and the lid plate 32. In this embodiment, the opening peripheral part 34 of the case main body 31 and the peripheral part of the cover plate 32 are joined by welding.

  The case main body 31 includes a plate-like closing part 311 and a cylindrical body part 312 connected to the periphery of the closing part 311.

  The closing portion 311 is located at the lower end of the case main body 31 when the case main body 31 is arranged so that the opening faces upward (that is, it becomes the bottom wall of the case main body 31 when the opening faces upward). ) Part. The blocking part 311 has a rectangular shape when viewed in the normal direction of the blocking part 311.

  The body portion 312 of the present embodiment has a rectangular tube shape. Specifically, the body portion 312 has a flat rectangular tube shape. The body portion 312 has a pair of long wall portions 313 extending from the long side at the periphery of the closing portion 311 and a pair of short wall portions 314 extending from the short side at the periphery of the closing portion 311. That is, the pair of long wall portions 313 are opposed to each other with a gap in the short side direction of the closing portion 311 (specifically, an interval corresponding to the short side of the periphery of the closing portion 311), and the pair of short wall portions 314 is closed. The portions 311 face each other with an interval (specifically, an interval corresponding to the long side of the periphery of the blocking portion 311) in the long piece direction. By connecting the end portions of the short wall portion 314 corresponding to the pair of long wall portions 313 (specifically, facing the short side direction), a rectangular tube-shaped body portion 312 is formed.

  As described above, the case body 31 has a rectangular tube shape (that is, a bottomed rectangular tube shape) in which one end portion in the opening direction (Z-axis direction) is closed.

  The lid plate 32 is a plate-like member that closes the opening of the case body 31. Specifically, the cover plate 32 contacts the case body 31 so as to close the opening of the case body 31. More specifically, the peripheral edge of the cover plate 32 is overlapped with the open peripheral edge 34 of the case body 31 so that the cover plate 32 closes the opening.

  The cover plate 32 has a contour shape corresponding to the opening peripheral edge 34 of the case body 31 when viewed in the Z-axis direction. That is, the lid plate 32 is a rectangular plate material that is long in the long side direction of the closing portion 311.

  The external terminal 4 is a part that is electrically connected to an external terminal of another power storage element or an external device. The external terminal 4 is formed of a conductive member. For example, the external terminal 4 is formed of a highly weldable metal material such as an aluminum-based metal material such as aluminum or an aluminum alloy, or a copper-based metal material such as copper or a copper alloy. The external terminal 4 has a surface 41 to which a bus bar or the like can be welded.

  The current collector 5 is disposed in the case 3 and is directly or indirectly connected to the electrode body 2 so as to be energized. The current collector 5 of the present embodiment is connected to the electrode body 2 through the clip member 50 so as to be energized. That is, the electrical storage element 1 includes a clip member 50 that connects the electrode body 2 and the current collector 5 so as to allow energization.

  The current collector 5 is formed of a conductive member. The current collector 5 is disposed along the inner surface of the case 3. The current collector 5 of the present embodiment connects the external terminal 4 and the clip member 50 shown in FIG. Specifically, as shown in FIGS. 3 and 8, the current collector 5 includes a first connection portion 51 connected to the external terminal 4 so as to be energized, and a second connection connected to the electrode body 2 so as to be energized. And a bent portion 53 connecting the first connecting portion 51 and the second connecting portion 52. In the current collector 5, the bent portion 53 is disposed in the vicinity of the boundary between the lid plate 32 and the short wall portion 314 in the case 3, the first connection portion 51 extends from the bent portion 53 along the lid plate 32, and the first Two connecting portions 52 extend from the bent portion 53 along the short wall portion 314. That is, the current collector 5 is formed in an L shape. The current collector 5 of the present embodiment is formed by bending a plate-shaped metal material cut into a predetermined shape.

  The current collector 5 configured as described above is disposed on each of the positive electrode and the negative electrode of the electricity storage device 1. In the power storage device 1 of the present embodiment, in the case 3, the positive electrode uncoated laminated portion 26 and the negative electrode uncoated laminated portion 26 of the electrode body 2 are respectively connected.

  The positive electrode current collector 5 and the negative electrode current collector 5 are formed of different materials. Specifically, the positive electrode current collector 5 is formed of, for example, aluminum or an aluminum alloy, and the negative electrode current collector 5 is formed of, for example, copper or a copper alloy.

  The clip member 50 shown in FIGS. 3 and 9 to 11 bundles the positive electrode 23 or the negative electrode 24 laminated in the uncoated laminated portion 26 (specifically, the bisected uncoated laminated portion 261) of the electrode body 2. Pinch. Thereby, the clip member 50 makes the positive electrodes 23 or the negative electrodes 24 stacked in the non-coated stacked portion 26 conductive. Specifically, the clip member 50 includes a pair of opposed pieces 501 that are opposed to each other with the uncoated laminated portion 261 (the laminated positive electrode 23 or the negative electrode 24) sandwiched therebetween, and corresponding one ends of the opposed piece 501. And a connecting portion 502 for connecting the two. The clip member 50 is formed of a conductive member. In the present embodiment, two clip members 50 are disposed on the positive uncoated laminate portion 26 of the electrode body 2, and two clip members 50 are disposed on the negative uncoated laminate portion 26.

  The power storage element 1 includes an insulating member 6 that insulates the electrode body 2 from the case 3. The insulating member 6 of this embodiment is an insulating cover, for example. As shown in FIGS. 2 and 3, the insulating member 6 is disposed between the case 3 (specifically, the case main body 31) and the electrode body 2. The insulating member 6 is formed of an insulating member. The insulating member 6 is configured by a sheet-like member. Insulating member 6 of this embodiment is formed with resin, such as polypropylene and polyphenylene sulfide, for example. The insulating cover 6 of this embodiment is formed in a bag shape by bending an insulating sheet-like member cut into a predetermined shape.

  In the electricity storage device 1 of the present embodiment, the electrode body 2 (specifically, the electrode body 2 and the current collector 5) accommodated in the bag-like insulating member 6 is accommodated in the case 3.

  Next, the manufacturing method of the electrical storage element 1 is demonstrated, also referring FIGS.

  First, the positive electrode 23 and the negative electrode 24 are cut into a predetermined length (step S1). Here, the positive electrode 23 before cutting has a certain thickness at each position in the longitudinal direction. On the other hand, the negative electrode 24 before cutting has a thin portion 240 at a midpoint in the longitudinal direction that is thinner than other portions (specifically, the overall thickness of the negative electrode 24 is smaller than that of the other portions). Here, the thin-walled portion 240 means “a portion having the metal foil 241 and the thin layer portion 242A in the negative electrode 24” and “a portion having the metal foil 241 in the negative electrode 24 but the negative electrode active material layer 242 (the thin layer portion 242A). It is a concept including “a part not including”.

  The thin portion 240 of this embodiment has a negative electrode active material layer (thin layer portion 242A) that is thinner than the negative electrode active material layer 242 in other portions of the negative electrode 24 (portions excluding the thin portion 240 in the negative electrode 24). Specifically, in the thin portion 240 of the negative electrode 24, a part of the thin layer portion 242 </ b> A in the length direction at a portion on one side of the negative electrode 24 (on the upper surface of the metal foil 241 in FIG. 12) and the other side of the negative electrode 24. A part of the thin layer portion 242A in the length direction at the portion (on the lower surface of the metal foil 241 in FIG. 12) overlaps in the thickness direction. That is, in the thin portion 240, as shown in FIG. 12, the thin layer portions 242A are provided on both sides of the metal foil 241 at positions where part of the longitudinal direction overlaps in the thickness direction. Note that the thin layer portion 242A of the present embodiment may be formed by thinning a part of the negative electrode active material layer 242 laminated on the metal foil 241 in the longitudinal direction by peeling, scraping, or the like. The thin layer portion 242A may be formed by thinly laminating a part in the longitudinal direction when the negative electrode active material layer 242 is laminated (formed) on the metal foil 241. In FIG. 12, the thicknesses of the metal foil 241, the negative electrode active material layer 242, and the thin layer portion 242A are exaggerated.

  The negative electrode 24 configured in this manner is cut along the short direction at the position where the thin layer portion 242A overlaps in the thickness direction with the metal foil 241 interposed therebetween (position α in the example shown in FIG. 12). The After the cutting, the negative electrode active material layer in the range indicated by I in FIG. 12 is the metal foil 241 at the end 245 on the innermost peripheral side of the negative electrode 24 in the wound body 22 formed by winding together with the positive electrode 23. The thin layer portion 242A is configured to be disposed on the surface facing outward (the surface facing the side opposite to the core 21). Further, the negative electrode active material layer in the range indicated by II is on the surface facing the inner side (surface facing the core 21 side) of the metal foil 241 at the innermost peripheral portion of the negative electrode 24 in the wound body 22. The thin layer portion 242A (see FIG. 7) provided (disposed) in the range from the innermost edge 245A to the position sandwiched by the positive electrode 23 in the wound body 22 Configure. Further, the negative electrode active material layer indicated by III constitutes a thin layer portion 242A disposed on the surface facing the inside of the metal foil 241 of the outermost peripheral end portion 246 of the negative electrode 24 in the wound body 22. . Further, the negative electrode active material layer in the range indicated by IV is a range on the surface facing the outside in the metal foil 241 at the outermost peripheral side portion of the negative electrode 24 in the wound body 22, and is the outermost end. A thin layer portion 242A (see FIG. 7) provided (disposed) in a range from the edge 246A to the position sandwiched by the positive electrode 23 in the wound body 22 is configured.

  Next, the surface of the negative electrode 24 on which the thin layer portion 242A is arranged is short in the longitudinal direction, and the end portion 245 on the innermost periphery when wound is directed outward, and the end portion 246 on the outermost periphery side. Then, the positive electrode 23 and the negative electrode 24 are stacked so as to face inward, and the stacked positive electrode 23 and negative electrode 24 are wound (step S2). That is, at the end 245 on the winding start side of the negative electrode 24, the short side surface faces the positive electrode 23 side (see FIG. 13), and at the end 246 on the winding end side, the short side surface is opposite to the positive electrode 23. The positive electrode 23 and the negative electrode 24 are overlapped so as to face the side, and the positive electrode 23 and the negative electrode 24 are wound in this overlapped state (see arrow β in FIG. 13). Thereby, the electrode body 2 is formed. In FIG. 13, the thicknesses of the metal foils 231 and 241, the positive electrode active material layer 232, the negative electrode active material layer 242, and the thin layer portion 242 </ b> A are exaggerated.

  The current collector 5 is joined to the formed electrode body 2 (step S3). Specifically, the positive electrode 23 (or the negative electrode 24) laminated in the uncoated laminated portion 26 (specifically, the bisected uncoated laminated portion 261) of each electrode of the electrode body 2 is sandwiched by the clip member 50, The clip member 50 and the current collector 5 are ultrasonically bonded in a state where they are overlapped. Thereby, the electrode body 2, the clip member 50, and the collector 5 are joined.

  The current collector 5 to which the electrode body 2 is connected, the external terminal 4 and the like are assembled to the cover plate 32 (step S4), and the electrode body 2 and the current collector 5 and the like are covered with the insulating member 6 so that these electrodes are covered. While the body 2 and the current collector 5 are inserted into the case main body 31, the opening of the case main body 31 is closed by the lid plate 32 (step S5). And the electrical storage element 1 is completed by welding the boundary part of the case main body 31 and the cover plate 32 (for example, laser welding) (step S6).

  According to the electricity storage device 1 manufactured by the above manufacturing method, the end of the negative electrode 24 (the part extending (protruded) from the corresponding edges 235A and 236A of the positive electrode 23, that is, the part not facing the positive electrode 23). ) The negative electrode active material layers 245 and 246 are the thin layer portions 242A. For this reason, at the time of charging / discharging of the electrical storage element 1, the edge part 245,246 of the negative electrode 24, and the other site | part (site | part facing the positive electrode 23: In the example of this embodiment, edge part 245,246 is the other part. The number of ions that can move from the other part to the end portions 245 and 246 can be suppressed even if a potential difference occurs between them. Thereby, in the electrical storage element 1, capacity degradation of the electrical storage element 1 due to the movement of ions in the negative electrode 24 (specifically, the negative electrode active material layer) is suppressed.

  Further, since the negative electrode 24 has the thin layer portion 242A on the surface of the metal foil 241 of the end portions 245 and 246 facing the corresponding edge 235A and 236A of the positive electrode 23, the negative electrode active region is formed on the surface. The rigidity of the negative electrode 24 (thin wall portion 240) is higher than when no material layer is provided. For this reason, in the electrical storage element 1, the shift | offset | difference and short circuit from the planned position by the edge parts 245 and 246 of the negative electrode 24 bending can be suppressed.

  Moreover, in the electrical storage element 1 of the present embodiment, the negative electrode 24 is a range on the inner-facing surface of the metal foil 241 at the innermost peripheral side, and from the innermost peripheral edge 245A in the winding direction. A thin layer portion 242A is provided in a range until reaching a position sandwiched between the positive electrodes 23 in the wound body 22 (see FIG. 7). Further, the negative electrode 24 is a range on the surface facing the outside in the metal foil 241 at the outermost peripheral side, and reaches the position sandwiched by the positive electrode 23 from the outermost peripheral edge 246A in the winding direction. The thin layer portion 242A is included in the range (see FIG. 7).

  According to these configurations, in the negative electrode 24, the innermost surface of the metal foil 241 faces the inner surface (the surface facing the core 21: the surface not facing the positive electrode 23) and the outermost surface. The negative electrode active material layer (thin layer portion) 242A on the surface facing the outer side of the metal foil 241 at the outer peripheral side (the surface facing the side opposite to the core 21: the surface not facing the positive electrode 23) is a positive electrode. It is thinner than the active material layer 242 at the part facing the 23. Thereby, at the time of charging / discharging of the electrical storage element 1, between the site | part of the said innermost circumference side and the said outermost circumference side site | part in the negative electrode 24, and the site | part except these site | parts of the innermost circumference side and the site | part of a disaster state Even if a potential difference occurs, the movement of ions to the innermost peripheral portion and the outermost peripheral portion can be suppressed. As a result, it is possible to more effectively suppress the capacity deterioration of the electricity storage element 1 due to the movement of the ions.

  Further, in the power storage device 1 of the present embodiment, the end portions 245 and 246 of the negative electrode have thin layer portions 242 </ b> A on both surfaces of the metal foil 241, respectively. For this reason, the rigidity of the end portions 245 and 246 of the negative electrode 24 is higher than when the thin layer portion 242A is not provided on both surfaces of the metal foil 241 or when the thin layer portion 242A is provided only on one surface of the metal foil 241. As a result, in the electricity storage element 1, it is possible to more reliably suppress a deviation or short circuit from the planned position due to the end portions 245 and 246 being bent.

When the negative electrode 24 having the non-coated portion 244 continuous in the longitudinal direction is cut in the width direction, the entire thickness of the negative electrode 24 changes at the boundary between the portion where the negative electrode active material layer 242 is formed and the non-coated portion 244. Therefore, in the vicinity of the boundary between the portion where the negative electrode active material layer 242 is formed and the non-covered portion 244, burrs and chips (specifically, the stress applied to the portion where the negative electrode active material layer 242 is formed and the uncovered portion 244). Burrs and chips caused by the difference from the stress applied to the steel.
In the method for manufacturing the electricity storage device 1 of the present embodiment, the negative electrode 24 before being cut into a predetermined length has the non-covered portion 243 that is continuous in the longitudinal direction, but other than the non-covered portion 244 and the non-covered portion. Since the thin-walled portion 240 in which the negative electrode active material layer 242A is thinned is cut from the change in the total thickness of the negative electrode 24 at the boundary with this part, the generation of the burrs and chips when cut can be suppressed. That is, when the negative electrode active material layer 242 is thick, the change in the overall thickness of the negative electrode 24 at the boundary between the portion where the negative electrode active material layer 242 is formed and the non-covered portion 244 is large. Although burrs and chips are likely to be generated, the thickness of the negative electrode active material layer 242A at the cutting site is suppressed as in the method for manufacturing the electricity storage device 1 of this embodiment, so that the burrs of the metal foil 241 at the time of cutting are reduced. And generation of chips can be suppressed.

  Further, as in the present embodiment, when the negative electrode active material layer 242 of the negative electrode 24 includes a component having a Vickers hardness greater than that of the metal foil 241 (in the example of the present embodiment, hard carbon), the negative electrode 24 is cut. The suppression of the generation of burrs and chips in the metal foil 241 at the time becomes more remarkable. That is, when the negative electrode active material layer 242 includes a component having a Vickers hardness larger than that of the metal foil 241, the metal foil 241 is more easily cut when the negative electrode 24 is cut as compared with a component having a lower Vickers hardness (for example, graphite). Since it is pressed by a component having a large Vickers hardness, burrs and chips are more likely to be generated. However, by suppressing the thickness of the negative electrode active material layer 242A, the negative electrode active material layer 242A has a component having a large Vickers hardness. Even if included, generation of burrs and chips in the metal foil 241 at the time of cutting is effectively suppressed.

  In addition, the electrical storage element of this invention and the manufacturing method of an electrical storage element are not limited to the said embodiment, Of course, a various change can be added in the range which does not deviate from the summary of this invention. For example, the configuration of another embodiment can be added to the configuration of a certain embodiment, and a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment. Furthermore, a part of the configuration of an embodiment can be deleted.

  In the negative electrode 24 of the above embodiment, the thin layer portions 242A are provided at both end portions 245 and 246 in the longitudinal direction (winding direction), but the present invention is not limited to this configuration. The thin layer portion 242A may be provided only on one end of the negative electrode 24 (the innermost end 245 or the outermost end 246).

  In the negative electrode 24 of the above embodiment, the thin layer portions 242A are provided on both surfaces (both surfaces in the thickness direction) of the end portions 245 and 246 in the longitudinal direction, but the present invention is not limited to this configuration. The thin layer portion 242 </ b> A may be provided in at least one of the outer portion of the innermost peripheral end 245 and the inner portion of the outermost peripheral end 246 in the negative electrode 24. Further, in the negative electrode 24, the thin portion 240 may have a configuration that does not include the negative electrode active material layer 242 (including the thin layer portion 242 </ b> A). Even with these configurations, even when a potential difference occurs between the end portions 245 and 246 of the negative electrode 24 and other parts (parts facing the positive electrode 23) during charging / discharging of the electricity storage device 1, the other Since the number of ions that can move from the portion to the ends 245 and 246 is reduced, capacity deterioration of the power storage element 1 due to the movement of ions in the negative electrode 24 (specifically, the negative electrode active material layer 242) can be suppressed. .

  Further, in the negative electrode 24 of the above-described embodiment, substantially the entire range from the innermost peripheral edge 245A in the winding direction to the position sandwiched by the positive electrode 23 in the wound body 22 in the portion facing inward. In addition, although the thin layer portion 242A is provided, it is not limited to this configuration. The thin layer portion 242A may be provided in a part of the range from the end edge 245A in the winding direction to the position sandwiched by the positive electrode 23 in the portion facing the inner side of the negative electrode 24. Similarly, in the negative electrode 24 of the above-described embodiment, substantially the entire range from the outermost edge 246A in the winding direction to the position sandwiched by the positive electrode 23 in the winding body 22 in the portion facing outward. In addition, although the thin layer portion 242A is provided, it is not limited to this configuration. The thin layer portion 242A may be provided in a part of a range from the end edge 246A in the winding direction to the position sandwiched between the positive electrodes 23 in a portion facing the outside of the negative electrode 24.

  In the negative electrode 24 of the above embodiment, the negative electrode active material layer 242 is directly formed (laminated) on both surfaces of the metal foil 241, but the configuration is not limited thereto. The negative electrode active material layer 242 may be configured to be indirectly formed (laminated) on the surface of the metal foil 241. For example, for the purpose of improving the adhesion or electronic conductivity between the metal foil 241 and the negative electrode active material layer 242, a conductive layer is formed (laminated) on the surface of the metal foil 241, and the surface of the conductive layer is formed. A negative electrode active material layer 242 may be formed (laminated) thereon.

  In the method for manufacturing the electricity storage device 1 of the above embodiment, in the thin portion 240 of the negative electrode 24 before being cut into a predetermined length, the thin layer portion 242A provided on both sides with the metal foil 241 interposed therebetween is a part in the longitudinal direction. However, the present invention is not limited to this configuration. As shown in FIG. 15, in the thin portion 240 of the negative electrode 24, the thin layer portion 242 </ b> A in one portion in the thickness direction of the negative electrode 24 and the thin layer portion 242 </ b> A in the other portion in the thickness direction of the negative electrode 24 However, they may overlap in the thickness direction, that is, the positions in the longitudinal direction may coincide. In FIG. 15, the thicknesses of the metal foil 241, the negative electrode active material layer 242, and the thin layer portion 242A are exaggerated.

  In the method for manufacturing the electricity storage device 1 of the above embodiment, the thinned portion 240 to be cut is the thin layer portion 242A in which the negative electrode active material layer 242 is thinner than other portions, but is not limited to this configuration. The thin portion 240 to be cut may have a configuration without the negative electrode active material layer 242. When the negative electrode 24 is configured to have the non-covered portion 243 that is continuous in the longitudinal direction, the configuration without the negative electrode active material layer 242 can suppress a change in the overall thickness of the negative electrode 24 in the width direction. Generation | occurrence | production of the burr | flash and chip at the time of cut | disconnecting the thin part 240 can be suppressed.

  Moreover, in the said embodiment, although the case where an electrical storage element was used as a nonaqueous electrolyte secondary battery (for example, lithium ion secondary battery) which can be charged / discharged was demonstrated, the kind and magnitude | size (capacity | capacitance) of an electrical storage element are arbitrary. It is. Moreover, in the said embodiment, although the lithium ion secondary battery was demonstrated as an example of an electrical storage element, it is not limited to this. For example, the present invention can also be applied to secondary batteries such as magnesium ion batteries or sodium ion batteries, as well as power storage elements of capacitors such as primary batteries and electric double layer capacitors.

  A power storage element (for example, a battery) may be used in a power storage device 11 (a battery module when the power storage element is a battery) 11 as shown in FIG. The power storage device 11 includes at least two power storage elements 1 and a bus bar member 12 that electrically connects two (different) power storage elements 1 to each other. In this case, the technique of the present invention only needs to be applied to at least one power storage element 1.

  DESCRIPTION OF SYMBOLS 1 ... Power storage element, 2 ... Electrode body, 21 ... Winding core, 22 ... Winding body, 23 ... Positive electrode, 231 ... Metal foil (conductive part), 232 ... Positive electrode active material layer, 233 ... Uncovered part, 234 ... Covering Part, 235A ... innermost edge, 236A ... outermost edge, 24 ... negative electrode, 240 ... thin part, 241 ... metal foil (conductive part), 242 ... negative electrode active material layer, 242A ... thin layer , 243 ... non-covering part, 244 ... covering part, 245 ... innermost peripheral end, 245A ... innermost peripheral edge, 246 ... outermost peripheral end, 246A ... outermost peripheral edge , 25 ... Separator, 26 ... Uncoated laminated part, 261 ... Divided uncoated laminated part, 27 ... Hollow part, 3 ... Case, 31 ... Case body, 311 ... Closed part, 312 ... Body part, 313 ... Long wall part 314: Short wall portion, 32: Cover plate, 33: Internal space, 34: Opening peripheral edge portion, 4 ... External terminal, 41 Surface, 5 ... Current collector, 50 ... Clip member, 501 ... Opposing piece, 502 ... Connection part, 51 ... First connection part, 52 ... Second connection part, 53 ... Bending part, 6 ... Insulating member (insulating cover) , 11 ... Power storage device, 12 ... Bus bar member

Claims (6)

An electrode body having a wound body wound in a state where the belt-like positive electrode and the negative electrode overlap with each other,
The negative electrode has a sheet-like conductive portion and an active material layer overlapping the conductive portion, and is located on the innermost periphery and the outermost periphery of the wound body,
At least one of the innermost end and the outermost end in the winding direction of the negative electrode extends in the winding direction from the corresponding edge of the positive electrode,
The end portion of the negative electrode extending from the corresponding edge has the active material layer thinner than the active material layer of the other part of the negative electrode on the surface of the conductive portion facing the corresponding edge side. Alternatively, a power storage element that does not include the active material layer. Ends extending from the corresponding edge are provided at the innermost peripheral portion and the outermost peripheral portion of the negative electrode,
The negative electrode is a range on a surface facing the inner side of the conductive portion of the innermost peripheral portion until reaching a position sandwiched by the positive electrode from the innermost peripheral edge in the winding direction. And the range of the outermost peripheral portion on the surface facing the outer side of the conductive portion until reaching the position sandwiched by the positive electrode from the outermost peripheral edge in the winding direction. 2. The power storage device according to claim 1, wherein in the range, the active material layer is thinner than the active material layer of the other part, or does not have the active material layer.   The end part of the negative electrode extended from the corresponding end part of the positive electrode has the active material layer thinner than the active material layer of the other part of the negative electrode on both surfaces of the conductive part, respectively. The electrical storage element as described in. A thin-walled portion provided in the middle of the longitudinal direction in a strip-shaped negative electrode having a sheet-like conductive portion and an active material layer overlapping with the conductive portion, and the other portion of the negative electrode on the surface of the conductive portion Cutting a thin-walled portion having an active material layer thinner than the active material layer or not having the active material layer along the short direction of the negative electrode;
The state in which the thin-walled portion constituting the longitudinal end of the negative electrode extends in the longitudinal direction from at least one of the one edge and the other edge in the longitudinal direction of the belt-like positive electrode after the cutting The positive electrode and the negative electrode are overlapped, and the stacked positive electrode and negative electrode are wound from the one edge side.   The said negative electrode is a manufacturing method of the electrical storage element of Claim 4 which has the non-coating part of the said active material layer continuous in the said longitudinal direction.   The method for manufacturing a storage element according to claim 5, wherein the active material layer of the negative electrode includes a component having a Vickers hardness larger than that of the conductive part.

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