Electric energy storage device

Abstract

A power storage device has a columnar wound body in which a first electrode and a second electrode are overlapped with a separator interposed therebetween. The first electrode has a first portion A, a second portion A, and a first connecting section that connects the first portion A and the second portion A, the first portion A and the second portion A facing each other. The connecting section is provided as a first exposure section in which a first collector body is exposed, without a first active material layer, in a band-shaped region of the first collector body along the winding direction of the wound body. The first portion A and the second portion A are portions having the first active-material layer on both sides of the first connecting section. The first portion A and the second portion A sandwich the second electrode with the separator interposed therebetween, and are wound along the winding direction to constitute the wound body.

Description

Technical Field

[0001] The present disclosure relates to a power storage device.

Background Art

[0002] With the expanding demand for in-vehicle applications and the like, there is a need for high-capacity and high-output secondary batteries.

[0003] To increase the capacity of a battery, simply increasing the electrode plate area would be sufficient. However, in this case, when high-output discharge is performed, the amount of heat generated increases, making it easier for the battery temperature to rise. If the battery continues to be used at a temperature above a certain level, internal deterioration occurs and the capacity decreases.

[0004] As a current collection method for realizing high output while suppressing internal heat generation of a battery, there are a multi-tab current collection method in which a plurality of tabs (internal leads) are connected to an electrode plate and the electrical connection between the electrode plate and a terminal plate or a battery can is made via the plurality of tabs, or a tabless current collection method in which an end portion or an end face of an electrode plate is electrically connected to a terminal plate or a battery can via, for example, a current collection plate.

[0005] As an example of the tabless current collection method, Patent Document 1 discloses a secondary battery in which a group of electrode plates formed by laminating a positive electrode plate having a positive electrode material attached to a positive electrode current collector and a negative electrode plate having a negative electrode material attached to a negative electrode current collector via a separator is housed in a battery container together with an electrolytic solution. In this battery, at least one side portion of the group of electrode plates has a current collector of any one of the electrode plates protruding, and a protruding ridge portion protruding toward the protruding portion of the current collector is provided on the current collection plate. By pressing the ridge portion of the current collection plate against the tip of the protruding portion of the current collector, a flat portion plastically deformed is formed on the current collector, and at the ridge portion, the flat portion of the current collector and the current collection plate are welded together.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the multi-tab current collection method, it is necessary to provide a plurality of regions (uncoated regions) in the electrode plate where the current collector is exposed without being covered by the electrode material layer. Therefore, when the number of tabs is increased to reduce resistance, the coated area of the electrode material decreases, and the capacity of the battery decreases.

[0008] In the tabless current collection method, low resistance can be achieved by directly connecting the end or end face of the electrode plate to an exterior component such as a terminal plate or a battery can. However, since the strength of the metal foil serving as the current collector is small, the metal foil may be excessively deformed when the end of the current collector is pressed against and welded to the exterior component. Considering the deformation of the foil, if the area of the end where the current collector is exposed is increased, the ratio of the coated area of the electrode material in the electrode plate decreases, and the capacity per unit volume of the battery decreases. Even when a current collection plate is used as an intermediate component, when the ends of the current collector are aggregated to improve the welding quality, it is necessary to secure a large area of the end where the current collector is exposed, and the capacity per unit volume of the battery decreases.

Means for Solving the Problems

[0009] One aspect of the present disclosure relates to a power storage device including a first electrode having a first current collector and a first active material layer supported on the first current collector, a second electrode having a second current collector and a second active material layer supported on the second current collector, and a separator interposed between the first electrode and the second electrode, wherein the first electrode and the second electrode are stacked via the separator to form a columnar wound body. The first electrode has a first portion A, a second portion A, and a first connecting portion connecting the first portion A and the second portion A. The first connecting portion is folded back so that the first portion A and the second portion A face each other. The first connecting portion is provided as a first exposed portion where the first current collector is exposed in a strip-shaped region of the first current collector along the winding direction of the wound body, and the first active material layer is not present. The first portion A and the second portion A are portions having the first active material layer on both sides of the first connecting portion. The first portion A and the second portion A sandwich the second electrode via the separator and are wound along the winding direction to form the wound body.

Advantages of the Invention

[0010] A high-capacity and high-output power storage device can be easily realized.

[0011] The novel features of the present invention are described in the appended claims. However, the present invention relates to both the configuration and the content, and will be better understood from the following detailed description in conjunction with the drawings, along with other objects and features of the present invention.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present disclosure will be described. In the following description, examples will be given to explain the embodiments of the present disclosure, but the present disclosure is not limited to the examples described below. In the following description, specific numerical values, materials, etc. may be exemplified, but other numerical values, materials, etc. may be applied as long as the effects of the present disclosure can be obtained.

[0014] The power storage device according to an embodiment of the present disclosure includes a first electrode, a second electrode, a separator interposed between the first electrode and the second electrode, and a first current collector plate electrically connected to the first current collector. The first electrode has a first current collector and a first active material layer carried on the first current collector. The second electrode has a second current collector and a second active material layer carried on the second current collector. The first electrode and the second electrode are stacked via the separator to form a columnar wound body.

[0015] The first electrode has a first portion A, a second portion A, and a first connection portion that connects and folds back the first portion A and the second portion A. Due to the folded first connection portion, the first portion A and the second portion A face each other with the second electrode and the separator interposed therebetween.

[0016] The first connection portion is provided as a first exposed portion where the first current collector is exposed without having the first active material layer in a strip-shaped region of the first current collector along the winding direction of the wound body. The first portion A and the second portion A are portions having the first active material layer on both sides of the first connection portion.

[0017] The first portion A and the second portion A sandwich the second electrode via the separator and are wound along the winding direction to form a wound body. Thereby, the power storage device can achieve both high capacity and high output.

[0018] The first part A and the second part A of the first electrode are separated via a first connecting part. As shown in the example figures described later, for example, in the state before forming the wound body, the first part A and the second part A face each other in the axial direction of winding with a strip-shaped current collector exposed part (first connecting part) extending along the winding direction therebetween interposed therebetween. The first electrode is folded back at the first connecting part and folded so that the first part A and the second part A overlap. Thereby, the cross section of the first electrode at the first connecting part has a V-shaped or U-shaped configuration, and the first part A and the second part A face each other. With the second electrode and the separator sandwiched between the opposing first part A and second part A, the first electrode is wound together with the second electrode and the separator to form a wound body. At this time, at one end face of the wound body, a first connecting part where the first current collector is exposed appears.

[0019] Since the first current collector is exposed at the first connecting part, the first connecting part can be connected to an exterior component such as a battery can or a terminal plate, or a current collecting plate, and current collection on the first electrode side can be performed. The first connecting part is bent or curved by approximately 180° from the first part toward the second part and has increased rigidity. Therefore, compared with the conventional configuration in which an exposed part having no active material layer is provided at an end part (side part) along the winding direction of the strip-shaped current collector, the collector exposed part is protruded at the end face of the wound body, and the end part of the protruded collector exposed part is joined to the current collecting plate, when pressing and welding the first connecting part to an exterior component or the like, it is possible to suppress a situation where the force due to pressing is too large and the collector exposed part is excessively deformed, making welding difficult. Since an optimum pressing force for welding can be applied without the collector exposed part being excessively deformed, welding can be stably performed.

[0020] The first electrode can be obtained, for example, by processing a strip-shaped sheet, but by winding a folded sheet such that the first part A and the second part A overlap, the length of the strip-shaped sheet in the winding direction may be half the length of the conventional configuration. Thereby, compared with the case of forming a wound body of the same diameter using only the first part A or the second part A, the winding length when forming the wound body becomes shorter, improving productivity.

[0021] The first part A is preferably continuous with the second part A via the first connecting part. For example, as described above, a first electrode having a first part A and a second part A spaced apart with the first connecting part therebetween can be bent or flexed at the first connecting part so that the first part A and the second part A overlap, thereby forming a first part A and a second part A that are continuous via the first connecting part.

[0022] The separator is preferably bent and folded, similar to the first electrode. The separator may be folded on the side opposite to the side where the first connecting part of the wound body is disposed so as to sandwich the first part A and the second part A, or may be folded on the side where the first connecting part of the wound body is disposed so as to sandwich the second electrode.

[0023] The separator may be in a bag shape. The bag-shaped separator may wrap the first part or the second part, or may wrap the second electrode.

[0024] A plurality of through holes may be formed along the winding direction in the first connecting part. The plurality of through holes formed along the winding direction serve as perforations when bending the first electrode, and the first electrode can be easily bent along the perforations. In addition, the through holes serve as holes through which the electrolytic solution passes in the power storage device after manufacture, and the liquid circulation property of the electrolytic solution is improved. The through holes may be formed in a region excluding the region that contacts the member to be joined at the connecting part.

[0025] The first connecting portion may have a shape having a plurality of folds, wrinkles, or bends along the winding direction. These folds, wrinkles, or bent shapes act as springs to relieve the pressing force applied during welding, suppress excessive deformation (mainly plastic deformation) of the first connecting portion, and prevent the pressing force from being transmitted to the first portion or the second portion. Further, as the elastic force of the connecting portion increases, it becomes easier to obtain a reaction force from the connecting portion to the member to be joined (current collector plate, can, sealing plate). Thereby, the first connecting portion can be stably welded to an exterior component or the like. Also, since the welding point (area) increases, the welding becomes stable. It is more stable for these multiple folds, wrinkles, or bends to act as springs when formed at locations in the connecting portion excluding the contact area with the member to be joined.

[0026] Similar to the first electrode, the second electrode may also have a first portion B, a second portion B, and a second connecting portion that is folded back and connects the first portion B and the second portion B. Due to the folded-back second connecting portion, the first portion B and the second portion B face each other with the first electrode and the separator interposed therebetween. The second connecting portion is provided as a second exposed portion where the second current collector is exposed in a strip-shaped region of the second current collector along the winding direction and does not have the second active material layer. The first portion B and the second portion B of the second electrode are portions having the second active material layer on both sides of the second connecting portion.

[0027] Similar to the first electrode, the second electrode can be formed by folding back a sheet-shaped electrode having a first portion B and a second portion B separated with the second connecting portion therebetween at the second connecting portion so that the first portion B and the second portion B overlap. With the first electrode and the separator sandwiched between the opposing first portion B and second portion B, the second electrode is wound together with the first electrode and the separator to form a wound body. At this time, the second connecting portion is disposed on the side opposite to the side where the first connecting portion of the wound body is disposed. At the other end face of the wound body on the side opposite to the side where the first connecting portion is disposed, the second connecting portion where the second current collector is exposed appears. Similar to the first connecting portion, the second connecting portion can be connected to an exterior component such as a battery can or a terminal plate, or a current collector plate to perform current collection on the second electrode side.

[0028] One of the first electrode and the second electrode constitutes the positive electrode of the power storage device, and the other of the first electrode and the second electrode constitutes the negative electrode of the power storage device. The first electrode may constitute the positive electrode of the power storage device, or the second electrode may constitute the positive electrode of the power storage device. Which of the positive electrode and the negative electrode of the power storage device is the first electrode having the first portion A, the second portion A, and the first connection portion can be freely determined according to the configuration of the power storage device and is not particularly limited.

[0029] The power storage device according to an embodiment of the present disclosure is suitable for being configured as, for example, a non-aqueous electrolyte secondary battery, an alkaline storage battery, or a capacitor, and contributes to increasing the output of the non-aqueous electrolyte battery. The non-aqueous electrolyte battery includes a lithium-ion secondary battery, an all-solid-state battery, and the like.

[0030] The power storage device usually includes a columnar wound body in which a positive electrode and a negative electrode are wound with a separator interposed therebetween, a case that houses the wound body, and the above-described current collector plate. The case has a cylindrical portion and a bottom portion that closes one end of the cylindrical portion. Inside the case, a columnar wound body in which a positive electrode and a negative electrode are wound with a separator interposed therebetween is housed such that one end face of the wound body faces the bottom portion. The other end of the cylindrical portion of the case has an opening. The opening of the case is closed in a state where the wound body is housed and is maintained airtight.

[0031] One of the positive electrode and the negative electrode of the wound body is usually electrically connected to the case. The other of the positive electrode and the negative electrode of the wound body is usually electrically connected to a terminal plate disposed on the other end side of the cylindrical portion. The terminal plate closes the opening formed at the other end of the cylindrical portion. The space between the opening of the cylindrical portion and the terminal plate is sealed airtight. The method of sealing the opening of the case is not particularly limited, and a known method can be used.

[0032] The first connection portion, which is the first electrode, may be electrically connected to the case or may be electrically connected to the terminal plate. Similarly, the second connection portion, which is the second electrode, may be electrically connected to the case or may be electrically connected to the terminal plate. The first connection portion and / or the second connection portion may be directly connected to the case by welding or the like, or may be directly connected to the terminal plate.

[0033] The first connecting portion and / or the second connecting portion may be electrically connected to the case or the terminal plate via a current collector plate. The current collector plate is electrically connected to the exposed portion of the first current collector in the first connecting portion or the exposed portion of the second current collector in the second connecting portion on the end face of the wound body, and can be electrically connected to the bottom of the case or the terminal plate.

[0034] Hereinafter, a power storage device according to an embodiment of the present disclosure will be specifically described with reference to the drawings, taking the case where it is used in a lithium-ion secondary battery as an example of the power storage device. In the following, the first electrode is described as the positive electrode of the power storage device and the second electrode is described as the negative electrode of the power storage device, but the present disclosure is not limited thereto.

[0035] FIGS. 1 and 2 are plan views showing the configurations of the positive electrode (first electrode) and the negative electrode (second electrode) of a power storage device according to an embodiment of the present disclosure before forming the wound body. FIG. 1 is a plan view showing the configuration of the positive electrode 10. FIG. 2 is a plan view showing the configuration of the negative electrode 20. FIG. 3 is a schematic diagram for explaining a method of forming a wound body by overlapping the positive electrode 10 and the negative electrode 20 with a separator interposed therebetween. In FIGS. 1 and 2, the winding direction and the axial direction of winding when forming the wound body are shown together.

[0036] The positive electrode 10 is in the form of a long sheet having the winding direction as the longitudinal direction. As shown in FIG. 1, the positive electrode 10 includes a positive electrode current collector (first current collector) 11 and a positive electrode active material layer (first active material layer) 12 supported thereon. The positive electrode active material layer 12 is formed on both surfaces of the positive electrode current collector 11.

[0037] The positive electrode 10 has a first portion 10X, a second portion 10Y, and a first connecting portion 10Z that connects the first portion 10X and the second portion 10Y. The first connecting portion 10Z is provided as a belt-like region along the winding direction of the wound body at a position that is central in the winding axis direction of the positive electrode 10. Through the first connecting portion 10Z, the first portion 10X and the second portion 10Y face each other in the winding axis direction.

[0038] The first part 10X and the second part 10Y are regions where the positive electrode active material layers 12 are supported on both sides of the positive electrode current collector 11. On the other hand, the first connection part 10Z is a region where a positive electrode current collector exposed part (first exposed part) 11x where the positive electrode current collector 11 is exposed is formed without the positive electrode active material layer 12. In the positive electrode 10, another current collector exposed part without the positive electrode active material layer 12 may be formed at a location other than the positive electrode current collector exposed part 11x. Note that the positive electrode current collector exposed part means a region on the positive electrode current collector 11 where the positive electrode active material layer 12 is not formed, and it is not necessary for the positive electrode current collector 11 itself to be exposed at the positive electrode current collector exposed part, and another conductive layer may be formed on the positive electrode current collector.

[0039] In the example of FIG. 1, positive electrode current collector exposed parts 11y without the positive electrode active material layer 12 are arranged at both end portions along the winding direction of the positive electrode 10. The positive electrode current collector exposed part 11y faces the first connection part 10Z (positive electrode current collector exposed part 11x) via the first part 10X or the second part 10Y. The end face of the positive electrode current collector exposed part 11y and the positive electrode 10 along the winding direction may be covered with an insulating layer (not shown), but it is not necessarily covered.

[0040] A plurality of through holes 10h are formed along the winding direction at positions symmetric in the winding axis direction of the first connection part 10Z. The plurality of through holes 10h act as perforations when the positive electrode 10 is bent and wound to produce a wound body. Note that the plurality of through holes 10h do not necessarily have to be formed.

[0041] The negative electrode 20 is a long sheet-like shape with the winding direction as the longitudinal direction, and as shown in FIG. 2, it includes a negative electrode current collector (second current collector) 21 and a negative electrode active material layer (second active material layer) 22 supported thereon. The negative electrode active material layer 22 is formed on both sides of the negative electrode current collector 21.

[0042] The negative electrode 20 has a first portion 20X, a second portion 20Y, and a second connecting portion 20Z that connects the first portion 20X and the second portion 20Y. The second connecting portion 20Z is provided as a strip-shaped region along the winding direction of the wound body at a position that is central in the winding axis direction of the negative electrode 20. Through the second connecting portion 20Z, the first portion 20X and the second portion 20Y face each other in the winding axis direction.

[0043] The first portion 20X and the second portion 20Y are regions where the negative electrode active material layer 22 is supported on both sides of the negative electrode current collector 21. On the other hand, the second connecting portion 20Z is a region where a negative electrode current collector exposed portion (second exposed portion) 21x where the negative electrode current collector 21 is exposed is formed without the negative electrode active material layer 22. In the negative electrode 20, another current collector exposed portion without the negative electrode active material layer 22 may be formed at a location other than the negative electrode current collector exposed portion 21x. Note that the negative electrode current collector exposed portion means a region on the negative electrode current collector 21 where the negative electrode active material layer 22 is not formed, and it is not necessary for the negative electrode current collector 21 itself to be exposed at the negative electrode current collector exposed portion, and another conductive layer may be formed on the negative electrode current collector.

[0044] In the example of FIG. 2, negative electrode current collector exposed portions 21y without the negative electrode active material layer 22 are arranged at both ends along the winding direction of the negative electrode 20. The negative electrode current collector exposed portion 21y faces the second connecting portion 20Z (negative electrode current collector exposed portion 21x) through the first portion 20X or the second portion 20Y. The end faces of the negative electrode current collector exposed portion 21y and along the winding direction of the negative electrode 20 are covered with an insulating layer (not shown), but it is not necessarily covered.

[0045] A plurality of through holes 20h are formed along the winding direction at positions that are symmetric in the winding axis direction of the second connecting portion 20Z. The plurality of through holes 20h act as perforations when the negative electrode 20 is bent to produce a wound body.

[0046] To form a wound body using the above-described positive electrode 10, negative electrode 20, and separator, for example, as shown in FIG. 3, the positive electrode 10 is folded into a mountain fold along the through-hole 10h. Prepare two separators 30 and fold each of them into a valley fold. One of the two valley-folded separators 30 is overlapped so as to cover both sides of the first portion 10X of the positive electrode 10, and the other is overlapped so as to cover both sides of the second portion 10Y of the positive electrode 10. The negative electrode 20 is folded into a valley fold along the through-hole 20h and overlapped with one of the valley-folded separators 30.

[0047] By winding the thus-folded positive electrode 10, negative electrode 20, and separator, a columnar wound body is obtained. The first connection portion 10Z of the positive electrode 10 is exposed on one end face of the wound body. The second connection portion 20Z of the negative electrode 20 is exposed on the other end face of the wound body. By electrically connecting the first connection portion 10Z and the second connection portion 20Z to an external component or the like, high output can be achieved while maintaining a high capacity of the power storage device.

[0048] The separator may be in a bag shape. In the example of FIG. 3, two bag-shaped separators may be placed over the positive electrode 10 such that one wraps the first portion 10X of the positive electrode 10 and the other wraps the second portion 10Y of the positive electrode 10, and the positive electrode 10 covered with the separator may be overlapped with the negative electrode 20. Two bag-shaped separators may be placed over the negative electrode 20 such that one wraps the first portion 20X of the negative electrode 20 and the other wraps the second portion 20Y of the negative electrode 20, and the negative electrode 20 covered with the separator may be overlapped with the positive electrode 10.

[0049] In the example of FIG. 3, since the separator 30 is bent on the side of the negative electrode 20, the second connection portion 20Z is prevented from being electrically connected to the first portion 10X or the second portion 10Y of the positive electrode 10 and short-circuiting. Therefore, in this case, it is not necessary to form the positive electrode current collector exposed portion 11y covered with the insulating layer in FIG. 1. The positive electrode active material layer can be supported on the entire surface of the positive electrode current collector except for the positive electrode current collector exposed portion 11x, and the capacity of the power storage device can be further improved.

[0050] In the wound body, the first connecting portion 10Z and the second connecting portion 20Z are pressed against an exterior component or the like and are electrically connected to the exterior component or the like by welding or the like. At this time, due to appropriate pressing, the contact portions of the first connecting portion 10Z and the second connecting portion 20Z with the exterior component or the like are deformed along the surface of the exterior component or the like. Thereby, the first connecting portion 10Z and the second connecting portion 20Z are in surface contact with the exterior component or the like. By performing welding at the surface contact portion, the reliability of the welding is improved and the electrical connection with the exterior component or the like becomes strong.

[0051] The first connecting portion and / or the second connecting portion may have a shape having a plurality of folds, pleats, or bends along the winding direction. These plurality of folds, pleats, or bend shapes are provided in the vicinity of the assumed welding location. FIG. 4 is an enlarged cross-sectional view showing an example of the first connecting portion 10Z (or the second connecting portion 20Z) having a fold, pleat, or bend shape in the wound body.

[0052] In the example of FIG. 4, the plurality of folds, pleats, or bend shapes arranged in the vicinity of the plane of the welding location serve to absorb or relieve the pressing force applied to the wound body during welding, suppress excessive deformation of the first connecting portion or the second connecting portion, and suppress the transmission of the pressing force to the first portion or the second portion. Thereby, the first connecting portion and / or the second connecting portion can be stably welded to an exterior component or the like. The plurality of folds, pleats, or bend shapes can be formed by press-forming a predetermined region of the first connecting portion 10Z or the second connecting portion 20Z with respect to the positive electrode 10 or the negative electrode 20 in the state of the sheet shown in FIG. 1 or FIG. 2.

[0053] FIG. 5 is a longitudinal sectional view showing the configuration of a battery (lithium ion secondary battery), which is an example of a power storage device according to an embodiment of the present disclosure. The battery 200 includes a wound body 100 formed by winding a positive electrode 10 and a negative electrode 20 with a separator 30 therebetween into a columnar shape, a non-aqueous electrolyte (not shown), a bottomed metal case 210 that houses the wound body 100 and the non-aqueous electrolyte, and a sealing plate 220 that seals the opening of the case 210. A gasket 221 is disposed at the peripheral edge of the sealing plate 220, and the inside of the case 210 is sealed by caulking the opening end of the case 210 to the gasket 221.

[0054] Of the two end faces of the wound body 100, one end face is in contact with the positive electrode current collector plate 14, and the other end face is in contact with the negative electrode current collector plate 24. The positive electrode current collector plate 14 is in contact with the positive electrode current collector exposed portion 11x at the first connection portion 10Z on one end face of the wound body 100, and the positive electrode current collector plate 14 and the positive electrode current collector exposed portion 11x are welded together. The other end of the tab lead 15, one end of which is connected to the positive electrode current collector plate 14, is connected to the inner surface of the sealing plate 220. Therefore, the sealing plate 220 functions as an external positive electrode terminal.

[0055] On the other hand, the negative electrode current collector plate 24 is in contact with the negative electrode current collector exposed portion 21x at the second connection portion 20Z on the other end face of the wound body 100, and the negative electrode current collector plate 24 and the negative electrode current collector exposed portion 21x are welded together. The negative electrode current collector plate 24 is welded to a welding member 25 provided on the inner bottom surface of the case 210. Therefore, the case 210 functions as an external negative electrode terminal.

[0056] The materials constituting the positive electrode current collector plate 14 and the negative electrode current collector plate 24 are determined according to the materials constituting the positive electrode and the negative electrode. For example, when used as a positive electrode current collector plate of a lithium ion secondary battery, the material of the positive electrode current collector plate 14 is, for example, aluminum, an aluminum alloy, titanium, stainless steel, or the like. The material of the positive electrode current collector plate 14 may be the same as the material of the positive electrode current collector 11. For example, when used as a negative electrode current collector plate of a lithium ion secondary battery, the material of the negative electrode current collector plate 24 is, for example, copper, a copper alloy, nickel, stainless steel, or the like. The material of the negative electrode current collector plate 24 may be the same as the material of the negative electrode current collector 21.

[0057] The exposed portion of the current collector and the current collecting plate can be joined by, for example, laser welding. The laser may be irradiated radially at a plurality of locations, for example, from the side opposite to the surface facing the end face of the wound body of the current collecting plate (i.e., the first main surface side).

[0058] (Positive electrode) For the positive electrode current collector 11, a sheet-like metal material is used. The sheet-like metal material may be a metal foil, a metal porous body, an etched metal, etc. As the metal material, aluminum, an aluminum alloy, nickel, titanium, etc. can be used. The thickness of the positive electrode current collector is, for example, 10 μm to 100 μm.

[0059] The positive electrode active material layer 12 contains, for example, a positive electrode active material, a conductive material, and a binder. The positive electrode active material layer 12 can be obtained, for example, by applying a positive electrode composite material slurry containing a positive electrode active material, a conductive material, and a binder to both sides of the positive electrode current collector 11, drying the coating film, and then rolling it. The positive electrode active material is a material that occludes and releases lithium ions. Examples of the positive electrode active material include lithium-containing transition metal oxides, transition metal fluorides, polyanions, fluorinated polyanions, transition metal sulfides, etc.

[0060] (Negative electrode) For the negative electrode current collector 21, a sheet-like metal material is used. The sheet-like metal material may be a metal foil, a metal porous body, an etched metal, etc. As the metal material, copper, a copper alloy, nickel, stainless steel, etc. can be used. The thickness of the negative electrode current collector is, for example, 10 μm to 100 μm.

[0061] The negative electrode active material layer 22 contains, for example, a negative electrode active material, a conductive agent, and a binder. The negative electrode active material layer 22 can be obtained, for example, by applying a negative electrode composite material slurry containing a negative electrode active material, a conductive material, and a binder to both sides of the negative electrode current collector 21, drying the coating film, and then rolling it. The negative electrode active material is a material that occludes and releases lithium ions. Examples of the negative electrode active material include carbon materials, metal compounds, alloys, ceramic materials, etc.

[0062] (Separator) As the separator 30, for example, a microporous membrane made of resin such as polyolefin, a woven fabric, a non-woven fabric, etc. can be used. The thickness of the separator is, for example, 10 to 300 μm, and preferably 10 to 40 μm.

[0063] (Non-aqueous electrolyte) The non-aqueous electrolyte has lithium ion conductivity and contains a lithium salt and a non-aqueous solvent for dissolving the lithium salt.

Industrial Applicability

[0064] Since the current collector plate according to the present disclosure can be used to realize a high-output power storage device, it is suitable for, for example, in-vehicle applications. The present invention has been described with respect to the preferred embodiments at the present time, but such a disclosure should not be construed in a limiting manner. Various modifications and alterations will undoubtedly become apparent to those skilled in the art in the technical field to which the present invention pertains upon reading the above disclosure. Therefore, the appended claims should be construed to encompass all modifications and alterations without departing from the true spirit and scope of the present invention.

Explanation of Reference Numerals

[0065] 100: Wound body 10: Positive electrode (first electrode) 10h: Through hole 10X: First part 10Y: Second part 10Z: First connecting part 11: Positive electrode current collector 11x, 11y: Positive electrode current collector exposed parts 12: Positive electrode active material layer 20: Negative electrode (second electrode) 20h: Through hole 20X: First part 20Y: Second part 20Z: Second connecting part 21: Negative electrode current collector 21x, 21y: Negative electrode current collector exposed parts 22: Negative electrode active material layer 30: Separator 200: Battery (energy storage device) 210: Case

Claims

1. A first electrode having a first current collector and a first active material layer supported on the first current collector; A second electrode having a second current collector and a second active material layer supported on the second current collector; A separator interposed between the first electrode and the second electrode, The first electrode and the second electrode are overlapped via the separator to form a columnar wound body, The first electrode has a first portion A, a second portion A, and a first connecting portion connecting the first portion A and the second portion A, and the first connecting portion is folded back so that the first portion A and the second portion A face each other, The first connecting portion is provided as a first exposed portion where the first current collector is exposed without the first active material layer in a strip-shaped region of the first current collector along the winding direction of the wound body, The first portion A and the second portion A are portions having the first active material layer on both sides of the first connecting portion, A power storage device in which the first portion A and the second portion A sandwich the second electrode via the separator and are wound along the winding direction to form the wound body.

2. The power storage device according to claim 1, wherein the separator is folded on the side opposite to the side where the first connecting portion of the wound body is disposed so as to sandwich the first portion A and the second portion A.

3. The power storage device according to claim 1, wherein the separator is folded so as to sandwich the second electrode on the side where the first connecting portion of the wound body is disposed.

4. The power storage device according to any one of claims 1 to 3, wherein a plurality of through holes are formed in the first connecting portion along the winding direction.

5. The power storage device according to any one of claims 1 to 4, wherein the first connecting portion has a shape having a plurality of folds, pleats, or bends along the winding direction.

6. The power storage device according to any one of claims 1 to 5, wherein the first connecting portion is electrically connected to a current collecting plate.

7. The second electrode has a first portion B, a second portion B, and a second connecting portion connecting the first portion B and the second portion B, and the second connecting portion is folded back so that the first portion B and the second portion B face each other, The second connecting portion is provided as a second exposed portion where the second current collector is exposed without the second active material layer in a strip-shaped region of the second current collector along the winding direction of the wound body, The first part B and the second part B of the second electrode are parts having the second active material layer on both sides of the second connecting part. The second connecting part is arranged on the side opposite to the side where the first connecting part of the wound body is arranged. The power storage device according to any one of claims 1 to 6, wherein in the wound body, the first part B and the second part B sandwich the first electrode via the separator.

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