Power storage device

Abstract

In the present invention, a cylindrical battery (10) comprises: an electrode body (14) in which a positive electrode (11) and a negative electrode (12) are disposed with a separator (13) interposed therebetween; and an outer can (16) that accommodates the electrode body (14). The negative electrode (12) has a first end constituting a lower end section and a second end constituting an upper end section in the axial direction (negative electrode width direction) which is a first direction. In the negative electrode (12), a current is collected from the first end side, and one or more notches (46) are provided at the second end. The electrode body (14) may be a wound electrode body in which the strip-shaped positive electrode (11) and the strip-shaped negative electrode (12) are wound with the separator (13) interposed therebetween.

Description

Power storage device

[0001] The present disclosure relates to an electricity storage device, for example, a battery or a capacitor.

[0002] A conventional energy storage device is a cylindrical secondary battery described in Patent Document 1. This cylindrical secondary battery includes an electrode assembly in which a positive electrode and a negative electrode are wound with a separator interposed therebetween, a bottomed cylindrical outer can that houses the electrode assembly, and a sealing body that closes the opening of the outer can. The positive electrode of the electrode assembly is electrically connected to the bottom surface of the sealing body via a positive electrode lead, and the negative electrode of the electrode assembly is electrically connected to the bottom of the outer can via a negative electrode lead.

[0003] Japanese Patent Application Laid-Open No. 2000-048825

[0004] In order to further improve the capacity and output of power storage devices and to enable stable charging and discharging in more severe environments, there is a need for further improving reliability. Therefore, an object of the present disclosure is to provide a highly reliable power storage device.

[0005] In order to solve the above problem, the energy storage device of the present disclosure comprises an electrode body in which a first electrode and a second electrode are arranged with a separator interposed therebetween, and an outer casing that houses the electrode body, wherein the first electrode has a first end and a second end in a first direction, and the first electrode is current-collected from the first end side and has one or more notches at the second end.

[0006] According to the present disclosure, a highly safe and reliable power storage device can be realized.

[0007] 3(a) is a schematic plan view of a positive electrode when developed into a strip shape, and FIG. 3(b) is a schematic plan view of a negative electrode when developed into a strip shape. FIG. 3(b) is a schematic plan view of a negative electrode of a reference example corresponding to FIG. 3(b). FIG. 3(b) is a schematic plan view of a negative electrode of a first modified example corresponding to FIG. 3(b). FIG. 3(b) is a schematic plan view of a negative electrode of a second modified example corresponding to FIG. 3(b).

[0008] Hereinafter, an embodiment of an energy storage device according to the present disclosure will be described in detail with reference to the drawings. The energy storage device according to the present disclosure may be a secondary battery using an aqueous electrolyte or a secondary battery using a nonaqueous electrolyte. The energy storage device according to the present disclosure may be a cylindrical battery having a cylindrical (e.g., bottomed cylindrical) outer can, a prismatic battery having a prismatic outer can, or a pouch-type battery having an outer body made of a laminate sheet. In these batteries, the cylindrical outer can, the prismatic outer can, and the laminate sheet form the outer body. Alternatively, the energy storage device according to the present disclosure may be a capacitor that is repeatedly charged and discharged. Below, a cylindrical secondary battery (lithium ion battery) using a nonaqueous electrolyte is illustrated as an example of an energy storage device according to one embodiment, but the energy storage device according to the present disclosure is not limited thereto.

[0009] When multiple embodiments and variations are included below, it is anticipated from the beginning that new embodiments can be constructed by appropriately combining their characteristic features. In the following embodiments, the same components are designated by the same reference numerals in the drawings, and redundant explanations are omitted. Furthermore, multiple drawings include schematic diagrams, and the dimensional ratios of the length, width, height, etc. of each component between different drawings do not necessarily match. In this specification, the sealing body 17 side in the axial direction (height direction) of the cylindrical battery 10 is referred to as "upper," and the bottom plate portion 68 side of the outer can 16 in the axial direction is referred to as "lower." The axial direction of the cylindrical battery 10 coincides with the height direction of the electrode assembly. Among the components described below, components not recited in the independent claims representing the highest concept are optional and not required.

[0010] Fig. 1 is an axial cross-sectional view of a battery 10 according to an embodiment of the present disclosure, and Fig. 2 is a perspective view illustrating the structure of an electrode assembly 14. As shown in Fig. 1, the battery 10 includes a wound electrode assembly 14, a non-aqueous electrolyte (not shown), a cylindrical metal outer can 16 with a bottom that houses the electrode assembly 14 and the non-aqueous electrolyte, and a sealing body 17.

[0011] As shown in FIG. 2 , the electrode assembly 14 has a wound structure in which a strip-shaped positive electrode 11 and a strip-shaped negative electrode 12 are wound with two strip-shaped separators 13 interposed therebetween. The negative electrode 12 constitutes a first electrode, and the positive electrode constitutes a second electrode. As shown in FIG. 2 , the positive electrode 11 protrudes upward from the negative electrode 12 and the separator 13, and the negative electrode 12 protrudes downward from the positive electrode 11 and the separator 13. The positive electrode 11 has a third exposed portion 31 in the second core (positive electrode core) 30 where a second mixture layer (positive electrode mixture layer) 32 is not provided (formed). The third exposed portion 31 extends from the start end to the end end of the winding direction of the strip-shaped positive electrode 11 at an upper end (fourth end of the positive electrode) in the axial direction (first direction). The upper end constitutes a second end of the negative electrode 12 and a fourth end of the positive electrode 11 in the axial direction. The negative electrode 12 has a first exposed portion 41 in which the first mixture layer (negative electrode mixture layer) 42 is not provided in the first core (negative electrode core) 40, at the lower end in the axial direction (first end of the negative electrode) from the start end to the end end in the winding direction of the strip-shaped negative electrode 12.

[0012] The upper axial end of the electrode body 14 (fourth end of the positive electrode) is constituted by the third exposed portion 31, and the lower axial end of the electrode body 14 (first end of the negative electrode) is constituted by the first exposed portion 41. The first mixture layer 42 is formed to have dimensions slightly larger than the second mixture layer 32 in order to prevent lithium precipitation. That is, the first mixture layer 42 is formed to be longer than the second mixture layer 32 in the first longitudinal direction and the width direction.

[0013] The non-aqueous electrolyte has ion conductivity (e.g., lithium ion conductivity). The non-aqueous electrolyte may be a liquid electrolyte (electrolytic solution) or a solid electrolyte. The liquid electrolyte (electrolytic solution) includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Examples of the non-aqueous solvent include esters, ethers, nitriles, amides, and mixed solvents of two or more of these. Examples of the non-aqueous solvent include ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and mixed solvents of these. The non-aqueous solvent may contain a halogen-substituted compound (e.g., fluoroethylene carbonate) in which at least a portion of the hydrogen atoms of these solvents are substituted with halogen atoms such as fluorine. The electrolyte salt may include, for example, LiPF ６Lithium salts such as

[0014] Examples of the solid electrolyte include solid or gel polymer electrolytes and inorganic solid electrolytes. The polymer electrolyte includes, for example, a lithium salt and a matrix polymer, or a non-aqueous solvent, a lithium salt, and a matrix polymer. Examples of the matrix polymer include a polymer material that absorbs the non-aqueous solvent and gels. Examples of the polymer material include fluororesin, acrylic resin, and polyether resin. Examples of the inorganic solid electrolyte include materials known in all-solid-state lithium ion secondary batteries (e.g., oxide-based solid electrolytes, sulfide-based solid electrolytes, halide-based solid electrolytes, etc.).

[0015] The positive electrode 11 includes a second core 30 and a second mixture layer 32 formed on both sides of the second core 30. The second core 30 can be made of a metal foil, such as aluminum or an aluminum alloy, that is stable within the potential range of the positive electrode 11, or a film with such a metal disposed on the surface. The second mixture layer 32 contains a positive electrode active material, a conductive agent, and a binder. The positive electrode 11 can be produced, for example, by applying a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, and a binder to the second core 30, drying the coating, and then compressing it to form the second mixture layer 32 on both sides of the second core 30. The second mixture layer 32 may be formed on only one side of the second core 30. Alternatively, the second mixture layer 32 may be formed by bonding a layered sheet to the second core. During bonding, a conductive adhesive containing conductive particles may be interposed between the second mixture layer 32 and the second core 30.

[0016] The positive electrode active material is mainly composed of a lithium-containing metal composite oxide. Examples of metal elements contained in the lithium-containing metal composite oxide include Ni, Co, Mn, Al, B, Mg, Ti, V, Cr, Fe, Cu, Zn, Ga, Sr, Zr, Nb, In, Sn, Ta, and W. An example of a preferred lithium-containing metal composite oxide is a composite oxide containing at least one of Ni, Co, Mn, and Al.

[0017] Examples of the conductive agent contained in the second mixture layer 32 include carbon materials such as carbon black, acetylene black, ketjen black, and graphite. Examples of the binder contained in the second mixture layer 32 include fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyimide resin, acrylic resin, and polyolefin resin. These resins may be used in combination with cellulose derivatives such as carboxymethyl cellulose (CMC) or a salt thereof, or polyethylene oxide (PEO).

[0018] The negative electrode 12 includes a first core 40 and a first mixture layer 42 formed on both sides of the first core 40. The first core 40 can be made of a metal foil, such as copper or a copper alloy, that is stable within the potential range of the negative electrode 12, or a film with such a metal disposed on the surface. The first mixture layer 42 contains a negative electrode active material and a binder. The negative electrode 12 can be produced, for example, by applying a negative electrode mixture slurry containing a negative electrode active material and a binder to the first core 40, drying the coating, and then compressing it to form the first mixture layer 42 on both sides of the first core 40. The first mixture layer 42 may be formed on only one side of the first core 40. Alternatively, a layered first mixture layer 42 may be bonded to the first core 40. When bonding the first core 40 and the first mixture layer 42, a conductive adhesive containing conductive particles may be interposed between the first core 40 and the first mixture layer 42.

[0019] The negative electrode active material generally uses a carbon material that reversibly absorbs and releases lithium ions. Preferred carbon materials are graphites such as natural graphite, such as flake graphite, lump graphite, and amorphous graphite, and artificial graphite, such as lump artificial graphite and graphitized mesophase carbon microbeads. The first mixture layer may contain a silicon (Si) material as the negative electrode active material. Furthermore, the negative electrode active material may be a metal other than Si that alloys with lithium, an alloy containing such a metal, or a compound containing such a metal.

[0020] As in the case of the positive electrode 11, the binder contained in the first mixture layer 42 may be a fluororesin, PAN, polyimide resin, acrylic resin, polyolefin resin, or the like, but is preferably styrene-butadiene rubber (SBR) or a modified product thereof. In addition to SBR or the like, the first mixture layer 42 may also contain, for example, CMC or a salt thereof, polyacrylic acid (PAA) or a salt thereof, polyvinyl alcohol, or the like.

[0021] A porous sheet having ion permeability and insulating properties is used for the separator 13. Specific examples of the porous sheet include a microporous thin film, a woven fabric, and a nonwoven fabric. Preferred materials for the separator 13 include polyolefin resins such as polyethylene and polypropylene, and cellulose. The separator 13 may have either a single-layer structure or a laminated structure. A heat-resistant layer or the like may be formed on the surface of the separator 13.

[0022] As shown in FIG. 1 , the battery 10 includes a lower current collector plate (negative electrode current collector plate) 18 made of a metal such as copper, iron, nickel, or a nickel alloy, located axially below the electrode assembly 14. The lower current collector plate 18 constitutes a first current-carrying member. In this embodiment, the lower current collector plate 18 includes a disk-shaped base 18a and a cylindrical protrusion 18b with a bottom, which is located at the center of the base 18a and protrudes downward in the axial direction. While the upper surface of the base 18a is pressed against a first exposed portion 41 that constitutes the lower axial end of the electrode assembly 14, a laser beam is irradiated from below onto the lower surface of the base 18a. This laser welding joins the first exposed portion 41 to the upper surface of the base 18a. Furthermore, a bottom plate portion 18c located at the tip of the protrusion 18b is placed on the upper surface of a bottom plate portion 68 of the outer can 16, and then a laser beam is irradiated onto the bottom plate portion 68 from below. By this laser welding, the lower current collecting plate 18 is joined to the bottom plate portion 68 and electrically joined to the outer can 16 .

[0023] In the above description, the first exposed portion 41 is electrically connected to the outer can 16 via the lower current collector plate 18. However, the negative electrode may be electrically connected to the outer can via one or more negative electrode leads protruding from the lower end of the electrode assembly. Alternatively, in addition to or instead of being electrically connected to the outer can via one or more negative electrode leads, the negative electrode may be electrically connected to the outer can by contacting a first exposed portion provided on the outermost periphery of the electrode assembly with the inner circumferential surface of the outer can. The first exposed portion 41 may also be directly bonded to the bottom plate of the outer can using a laser or the like. The first exposed portion 41 may also be bonded to the lower current collector plate 18 in a radially bent state. Furthermore, the first exposed portions 41 aligned radially may also be bonded to the lower current collector plate 18 in a state where they overlap each other.

[0024] The battery 10 includes an upper current collector 19 (positive electrode current collector) made of a metal such as aluminum or an aluminum alloy, located axially above the electrode assembly 14. The upper current collector 19 constitutes a second current-carrying member. The upper current collector 19 has a base 19a electrically connected to the positive electrode 11 and a through-hole 19b located at the center of the base 19a. A spacer 37 made of an insulating material that prevents connection between the upper current collector 19 and the outer can 16 is provided between the base 19a and the outer can 16. While the lower surface of the base 19a is pressed against a third exposed portion 31 that constitutes the upper end of the electrode assembly 14, a laser beam is irradiated from above onto the upper surface of the base 19a. This laser welding bonds the third exposed portion 31 to the lower surface of the base 19a.

[0025] The tip end of the third exposed portion 31 may be bent in the radial direction and joined to the upper current collecting plate 19. Furthermore, the third exposed portions aligned in the radial direction may be joined to the upper current collecting plate 19 in a state where they overlap each other. A lead connected to the positive electrode 11 may be joined to the upper surface of the base 19a through the through hole 19b.

[0026] The sealing body 17 is formed by a terminal cap 27. The terminal cap 27 is made of metal. The terminal cap 27 has a disk-shaped base 27a and a protrusion 27b, and the protrusion 27b includes, for example, a cylindrical protrusion. The base 27a of the terminal cap 27 may be connected to the upper surface of the base 19a of the upper current collector plate 19 via a strip-shaped lead 55. Welding can be used as a method for joining the lead 55 to the base 27a and the base 19a. For example, the terminal cap 27 and the upper current collector plate 19 are electrically connected by laser welding.

[0027] The outer can 16 is generally made of a metal primarily composed of iron, such as nickel-plated iron. The outer can 16 may also be made of a metal primarily composed of aluminum or the like. The outer can 16 has a cylindrical portion 65 and a bottom plate portion 68. The cylindrical portion 65 includes an annular groove portion 35 and an annular shoulder portion 38. The groove portion 35 is formed by spinning a portion of the cylindrical portion 65 to recess it radially inward around the entire circumferential direction. The shoulder portion 38 is formed when the upper end of the cylindrical portion 65 is bent radially inward and crimped onto the peripheral edge portion 48 of the sealing body 17, and extends radially inward at the upper end of the cylindrical portion 65.

[0028] The peripheral edge 48 of the terminal cap 27 is crimped between the shoulder 38 and the groove 35 via the gasket 28, thereby fixing the sealing body 17 to the outer can 16. The gasket 28 serves as a sealing material to maintain airtightness inside the battery and as an insulating material to insulate the outer can 16 from the sealing body 17. The gasket 28 is made of, for example, polyolefin. The groove 35 is formed at a position a predetermined distance from the upper end of the outer can 16. The predetermined length is, for example, a length equivalent to 1 to 20% of the axial length of the outer can 16. The gasket 28 is compressed by the shoulder 38. The gasket 28 has a protrusion 28a that protrudes radially inward from between the shoulder 38 and the sealing body 17.

[0029] A thin, easily breakable portion 69 is provided on the bottom plate portion 68. The easily breakable portion 69 is provided, for example, by stamping a circle or a C-shape on the underside of the bottom plate portion 68. When the battery 10 generates abnormal heat and the internal pressure of the battery 10 rises to a predetermined pressure, the easily breakable portion 69 breaks and gas is released from the bottom plate portion 68. This gas release prevents the internal pressure of the battery 10 from rising excessively, which could cause the battery 10 to explode, thereby increasing the safety of the battery 10.

[0030] The battery 10 further includes an annular metal plate 80 and an annular insulating plate 82 made of an insulating material. The metal plate 80 includes a radially extending portion that extends substantially radially, and the radially extending portion is joined to the upper surface of the shoulder portion 38. The terminal cap 27, to which the third exposed portion 31 is electrically connected via the upper current collector plate 19, serves as the positive terminal, and the metal plate 80, to which the first exposed portion 41 is electrically connected via the outer can 16 to the lower current collector plate 18, serves as the negative terminal. The metal plate 80 is electrically connected to a current collector plate (not shown) that connects multiple batteries 10 in series or parallel, for example, using the tongue portion (lead) of the current collector plate. This configuration allows multiple cylindrical batteries 10 to be easily electrically connected to the current collector plate.

[0031] The insulating plate 82 is interposed between the metal plate 80 and the sealing body 17 to insulate the metal plate 80 from the sealing body 17. The outer peripheral edge of the insulating plate 82 on the radially outer side may be located above the protruding portion 28a of the gasket 28 and may be in contact with the gasket 28. In this manner, the metal plate 80 is insulated from the sealing body 17 by the gasket 28 and the insulating plate 82. The periphery of the hollow portion of the insulating plate 82 includes a cylindrical portion 83 that covers the outer peripheral surface of the protruding portion 27b of the terminal cap 27. The cylindrical portion 83 is connected to the radially inner end of the plate-shaped base of the insulating plate 82. Note that the battery does not necessarily have to have a metal plate and an insulating plate.

[0032] FIG. 3( a) is a schematic plan view of the positive electrode 11 when unfolded into a strip, and FIG. 3( b) is a schematic plan view of the negative electrode 12 when unfolded into a strip. As shown in FIG. 3( a), the positive electrode 11 has a resin layer 33 on both the outer and inner surfaces of the winding, in which an insulating resin such as polyvinylidene fluoride (PVdF) is disposed on the second core 30. The resin layer 33 is provided to prevent short-circuiting between the positive electrode 11 and the negative electrode 12. The resin layer 33 is provided on both sides of the positive electrode 11 from the start end to the end end in the winding direction. The resin layer 33 is disposed between the third exposed portion 31 and the second mixture layer 32 in the positive electrode width direction.

[0033] As shown in FIG. 3( b), the negative electrode 12 has multiple notches 46 at its upper end (second end). In this embodiment, the notches 46 have a rectangular slit shape; however, the notches may have any shape, such as a square, an isosceles triangle, or a semicircular shape. The notches 46 can be formed, for example, by cutting a portion of the upper end of the negative electrode 12 using a laser beam or a rotary blade. The multiple notches 46 are spaced apart in the first longitudinal direction (negative electrode longitudinal direction), and in this embodiment, are arranged at approximately equal intervals in the first longitudinal direction. As shown in FIG. 2, the notches 46 are provided axially above the second mixture layer 32. In this manner, even when the notches 46 are provided, deterioration is suppressed. The notches 46 may be formed in the negative electrode 12 in a region facing the second mixture layer 32.

[0034] Next, the effects achieved by providing the notch 46 in the negative electrode 12 will be described. When the battery 10 is repeatedly charged and discharged many times, the positive electrode 11 and the negative electrode 12 may expand in the axial direction (height direction of the electrode body). Expansion and contraction during charging and discharging occur in the negative electrode 12. The negative electrode 12 expands in the radial and axial directions during charging. It is presumed that the axial expansion of the negative electrode 12 occurs due to the expansion of the negative electrode during charging.

[0035] In light of this background, as shown in Fig. 4, that is, a schematic plan view of the negative electrode of the reference example corresponding to Fig. 3(b), if the negative electrode 312 has a simple rectangular shape, the separator 13 insulating the positive electrode 11 and the negative electrode 12 may be damaged at the upper end (edge) 312a of the negative electrode 312 as the negative electrode 312 expands in the negative electrode width direction. Damage to the separator 13 may cause the negative electrode 312 to come into contact with the third exposed portion 31, or, when current is collected from the positive electrode 11 to a current-carrying member (second current-carrying member) via a lead, there is a risk of the negative electrode 312 coming into contact with the lead.

[0036] In contrast, in the battery 10 of the present disclosure, the negative electrode 12 has a plurality of notches 46 at its upper end, spaced apart in the negative electrode longitudinal direction (first longitudinal direction). These notches 46 reduce the rigidity of the upper end (edge) of the negative electrode 12. Therefore, even if the negative electrode 12 elongates in the axial direction and the edge of the negative electrode 12 presses against the separator 13, the edge of the negative electrode 12 is more likely to bend due to the force received from the separator 13, thereby preventing damage to the separator 13. This prevents contact between the positive electrode 11 and the negative electrode 12, thereby improving the reliability of the battery 10.

[0037] The present disclosure is not limited to the above-described embodiment and its modifications, and various improvements and modifications are possible within the scope of the claims of the present application and their equivalents.

[0038] For example, in the above embodiment, the case has been described in which the entire upper end portion of the negative electrode 12 is included in the first mixture layer 42, and the first mixture layer 42 is provided with the notch 46. However, as shown in FIG. 5 , the negative electrode 112 may have a second exposed portion 139 extending in the first longitudinal direction at the upper end portion. At least a portion of the notch 146 may be provided in the second exposed portion 139. In this way, the rigidity of the upper end portion (edge) of the negative electrode 112 can be further reduced, thereby further preventing the edge of the negative electrode 112 from damaging the separator 13.

[0039] In the above embodiment, the case where the plurality of notches 46 are spaced apart over the entire area between both ends in the first longitudinal direction has been described. However, one or more notches do not have to be provided over the entire area between both ends in the first longitudinal direction, and may be provided locally with respect to the first longitudinal direction.

[0040] For example, depending on the specifications, the axial elongation of the positive electrode and negative electrode may be significant at the winding start side of the electrode assembly. In this case, as shown in Figure 6, one or more notches 246 may be provided only at the winding start side of the upper end of the negative electrode 212. In this case, damage to the separator 13 can be effectively suppressed with a small number of notches 246.

[0041] Furthermore, although the case where the third exposed portion 31 provided at the upper end (fourth end) of the positive electrode 11 is joined to the sealing body 17 has been described, the positive electrode may be joined to the sealing body using one or more positive electrode leads. One or more notches may be locally provided around a region at the upper end (second end) of the negative electrode that faces one or more positive electrode leads in the radial direction via the separator. In this case, if at least a portion of the notch is provided in a position that radially overlaps the positive electrode lead via the separator, contact between the negative electrode and the positive electrode lead can be effectively suppressed.

[0042] The case where the first electrode is a negative electrode has been described. However, the positive electrode may also expand in the height direction (axial direction) of the electrode body due to the following phenomenon. Specifically, expansion and contraction during charging and discharging occurs in the negative electrode, which expands radially and axially during charging. During charging, the radial expansion of the negative electrode increases the radial surface pressure within the electrode body. Therefore, the axial expansion of the negative electrode pulls the positive electrode in the height direction of the electrode body, making it more likely to expand axially.

[0043] On the other hand, during discharge, the radial contraction of the negative electrode reduces the radial surface pressure within the electrode body, so the positive electrode is not pulled back by the contraction of the negative electrode in the height direction of the electrode body. As a result, after repeated charge and discharge, the positive electrode elongates in the height direction of the electrode body. To prevent this phenomenon, one or more notches may be provided in the axial lower end (third end) of the positive electrode. In this case, contact between the positive electrode and the lower end (first end) of the negative electrode due to axial expansion of the positive electrode can be suppressed. Furthermore, although the invention of the present disclosure has been described assuming that the first electrode is a negative electrode, the first electrode may also be a positive electrode.

[0044] The structure of the sealing body is not limited to that of the embodiment. The sealing body may have a laminated structure including two rupture plates (a lower valve body and an upper valve body), and a convex terminal cap may be present to cover the rupture plate. Alternatively, the sealing body may be composed of only a rupture plate, or may have a structure in which, from the electrode body side, an internal terminal plate, an annular insulating plate, and a rupture plate are laminated. Furthermore, the bottom plate portion of the outer can does not necessarily have a thin, easily breakable portion. Note that the first electrode (e.g., a negative electrode) does not necessarily have to be connected to the outer can at the first end. A through hole may be formed in the bottom plate portion of the outer can, and the first electrode may be connected to a terminal inserted through the through hole. As described above, the first electrode may be connected to the first current-carrying member.

[0045] The power storage device of the present disclosure may have the following configurations. Configuration 1: A power storage device including an electrode assembly in which a first electrode and a second electrode are arranged with a separator interposed therebetween, and an exterior housing that houses the electrode assembly, wherein the first electrode has a first end and a second end in a first direction, current is collected from the first end side of the first electrode, and the second end has one or more notches. Configuration 2: The power storage device of claim 1, wherein the first electrode, the second electrode, and the separator are each strip-shaped, and the electrode assembly is a wound electrode assembly in which the first electrode and the second electrode are wound with the separator interposed therebetween. Configuration 3: The power storage device of claim 1 or 2, wherein the one or more notches extend in the first direction. Configuration 4: The power storage device of any one of claims 1 to 3, wherein the one or more notches are a plurality of notches, and the plurality of notches are formed at the second end at intervals in the first longitudinal direction of the first electrode. 10. The power storage device of claim 2, further comprising: a first current-carrying member electrically connected to the first electrode; a first exposed portion at the first end where the first current-carrying member is not formed and the first core is exposed; and the first exposed portion is formed at the first end where the first current-carrying member is not formed and the first core is exposed; and the first current-carrying member and the first exposed portion are joined. 11. The power storage device of claim 2, further comprising: a first current-carrying member electrically connected to the first electrode; a first exposed portion at the second end where the first current-carrying member is not formed and the first core is exposed; and the first exposed portion is formed at the second end where the first current-carrying member is not formed and the first core is exposed; and the one or more notches are at least partially formed in the second exposed portion. Configuration 8: The energy storage device of any one of claims 2 to 7, further comprising a second current-carrying member electrically connected to the second electrode, wherein in the first direction, the second electrode has a third end arranged on the side of the first end and a fourth end arranged on the side of the second end, and a third exposed portion is formed at the fourth end where the second mixture layer extending in a second longitudinal direction of the second electrode is not formed and the second core is exposed, and the second current-carrying member and the third exposed portion are joined.

[0046] REFERENCE SIGNS LIST 10 Battery (electricity storage device), 11 Positive electrode (second electrode), 12, 112, 212 Negative electrode (first electrode), 13 Separator, 14 Electrode body, 16 Outer can (outer body), 17 Sealing body, 18 Lower current collector plate, 18a Base, 18b Protruding portion, 19 Upper current collector plate, 19a Base, 19b Through hole, 27 Terminal cap, 27a Base, 27b Protruding portion, 28 Gasket, 28a Protruding portion, 30 Second core, 31 Third exposed portion, 32 Second mixture layer, 33 Resin layer, 35 Groove portion, 37 Spacer, 38 Shoulder portion, 40 First core, 41 First exposed portion, 42 First mixture layer 46, 146, 246 Notch, 48 Peripheral edge portion, 55 Strip-shaped lead, 65 Cylindrical portion, 68 Bottom plate portion, 69 Easily breakable portion, 80 Metal plate, 82 Insulating plate, 83 Cylindrical portion, 139 Second exposed portion.

Claims

1. An energy storage device comprising: an electrode assembly in which a first electrode and a second electrode are arranged with a separator between them; and an exterior housing that houses the electrode assembly, wherein the first electrode has a first end and a second end in a first direction, and the first electrode is electrically charged from the side of the first end and has one or more notches in the second end.

2. The energy storage device according to claim 1, wherein the first electrode, the second electrode and the separator are each strip-shaped, and the electrode body is a wound electrode body in which the first electrode and the second electrode are wound with the separator interposed therebetween.

3. The power storage device according to claim 1, wherein the one or more cutouts extend in the first direction.

4. The energy storage device according to claim 2, wherein the one or more cutouts are a plurality of cutouts, and the plurality of cutouts are formed at the second end at intervals in the first longitudinal direction of the first electrode.

5. An energy storage device according to any one of claims 2 to 4, wherein the first electrode has a strip-shaped first core and a first mixture layer arranged on the first core, and the second electrode has a strip-shaped second core and a second mixture layer arranged on the second core.

6. An energy storage device as described in any one of claims 2 to 4, further comprising a first conductive member electrically connected to the first electrode, wherein a first exposed portion is formed at the first end in which the first composite layer extending in a first longitudinal direction of the first electrode is not formed and the first core is exposed, and the first conductive member and the first exposed portion are joined.

7. A storage device as described in any one of claims 2 to 4, wherein a second exposed portion is formed at the second end, in which the first composite layer extending in the first longitudinal direction of the first electrode is not formed and the first core is exposed, and at least a portion of the one or more notches is formed in the second exposed portion.

8. An energy storage device as described in any one of claims 2 to 4, further comprising a second conductive member electrically connected to the second electrode, wherein in the first direction, the second electrode has a third end arranged on the side of the first end and a fourth end arranged on the side of the second end, and a third exposed portion is formed at the fourth end in which the second core is exposed without the second mixture layer extending in the second longitudinal direction of the second electrode, and the second conductive member and the third exposed portion are joined.

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