Secondary battery

Abstract

Provided is a secondary battery capable of suppressing deformation of a polar plate associated with charging and discharging. A secondary battery has an electrode body in which a positive electrode (11) and a negative electrode (12) in which a negative electrode mixture layer (50) is disposed on a negative electrode core (48) are wound with a separator interposed therebetween, and the negative electrode (12) has an outer-circumferential non-facing portion (44) and an inner-circumferential non-facing portion (46), which do not face the positive electrode (11) with the separator interposed therebetween, at a winding-start-side end portion, and is characterized in that: the outer-circumferential non-facing portion (44) and the inner-circumferential non-facing portion (46) are formed by winding a positive electrode (11) and a negative electrode mixture layer (50) on the negative electrode core (48); the first insulating tape (52a) is disposed on the outer-peripheral non-facing portion (44) and the second insulating tape (52b) is disposed on the inner-peripheral non-facing portion (46), and the first insulating tape (52a) is disposed on the outer-peripheral non-facing portion (44) in a range of 1.5 turns or more in the circumferential direction of the outer-peripheral non-facing portion (44), and the second insulating tape (52b) is disposed on the inner-peripheral non-facing portion (46) in a range of 1.5 turns or more in the circumferential direction of the outer-peripheral non-facing portion (44). The second insulating tape (52b) is disposed on the inner circumferential side non-facing portion (46) in a range of 0.9 turns or more in the circumferential direction of the inner circumferential side non-facing portion (46).

Description

Technical Field

[0001] This disclosure relates to a secondary battery. Background Technology

[0002] Lithium-ion batteries and other rechargeable batteries are used as power sources in a wide range of devices, primarily electric vehicles, and there is a growing demand for higher capacity. However, in rechargeable batteries with wound electrode bodies consisting of positive and negative electrodes wound together with a separator, stress is locally applied within the electrode body during charging and discharging as the electrode body expands. This can potentially cause electrode plate deformation, resulting in deformation of at least one of the positive or negative electrodes. In particular, since localized stress is easily applied at the center of the electrode body (the core portion), electrode plate deformation is prone to occur at the initial winding end of the electrode.

[0003] For example, Patent Document 1 discloses a non-aqueous electrolyte secondary battery comprising a wound electrode body in which a positive electrode and a negative electrode are wound in a spiral shape with a separator in between. The negative electrode has a negative electrode active material layer formed on the surface of a strip-shaped negative electrode current collector. The negative electrode includes a negative electrode lead that is joined to the starting winding end of the negative electrode current collector, and is wound in a manner that is separated from the positive electrode by the separator and not facing the inner end in the winding direction at least one turn. It also includes an insulating tape that is attached to the negative electrode current collector in a manner that crosses the surface of the negative electrode lead in the winding direction. According to Patent Document 1, by attaching the insulating tape to the negative electrode current collector in a manner that crosses the surface of the negative electrode lead, it is possible to suppress the deformation of the electrode plates that occurs during charging and discharging.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2018 / 180748 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] However, in existing technologies, electrode plate deformation can sometimes occur depending on charging and discharging conditions, leaving room for improvement. It should be noted that electrode plate deformation can potentially lead to internal short circuits and self-discharge within the battery; therefore, suppressing electrode plate deformation is crucial.

[0009] Therefore, the object of the present invention is to provide a secondary battery capable of suppressing electrode plate deformation during charging and discharging.

[0010] Solution for solving the problem

[0011] This disclosure relates to a secondary battery, characterized in that it has an electrode body formed by winding a positive electrode and a negative electrode having a negative electrode composite material layer disposed on a negative electrode core, separated by a separator. The negative electrode has an outer peripheral non-opposing portion and an inner peripheral non-opposing portion at the beginning winding end, separated by the separator but not facing the positive electrode, and has a first insulating strip disposed on the outer peripheral non-opposing portion and a second insulating strip disposed on the inner peripheral non-opposing portion. The first insulating strip is disposed on the outer peripheral non-opposing portion within a range of 1.5 turns or more along the circumference of the outer peripheral non-opposing portion, and the second insulating strip is disposed on the inner peripheral non-opposing portion within a range of 0.9 turns or more along the circumference of the inner peripheral non-opposing portion.

[0012] The effects of the invention

[0013] According to this disclosure, a secondary battery capable of suppressing plate deformation during charging and discharging can be provided. Attached Figure Description

[0014] Figure 1 This is a schematic cross-sectional view of a secondary battery as an example of an implementation method.

[0015] Figure 2 To illustrate Figure 1 A diagram of the inner end portion of the electrode body with AA cross section in the winding direction.

[0016] Figure 3 A schematic cross-sectional view showing the state of the negative and positive electrodes at the beginning of winding before winding.

[0017] Figure 4 This is a schematic cross-sectional view illustrating an example of the structure of an insulating tape.

[0018] Figure 5 A schematic cross-sectional view showing the state of the negative and positive electrodes at the beginning of winding before winding in Embodiment 1.

[0019] Figure 6 A schematic cross-sectional view showing the state of the negative and positive electrodes at the beginning of winding before winding in Embodiment 2.

[0020] Figure 7 This is a schematic cross-sectional view showing the state of the negative and positive electrodes at the beginning of winding before winding in Example 3.

[0021] Figure 8 A schematic cross-sectional view showing the state of the negative and positive electrodes at the beginning of winding before winding in Comparative Example 1.

[0022] Figure 9 A schematic cross-sectional view showing the state of the negative and positive electrodes at the beginning of winding before winding in Comparative Example 2.

[0023] Figure 10 A schematic cross-sectional view showing the state of the negative and positive electrodes at the beginning of winding before winding in Comparative Example 3.

[0024] Figure 11 A schematic cross-sectional view showing the state of the negative and positive electrodes at the beginning of winding before winding in Comparative Example 4. Detailed Implementation

[0025] The following is a detailed description of one embodiment of the secondary battery involved in this disclosure.

[0026] Figure 1 This is a schematic cross-sectional view of a secondary battery as an example of an implementation method. Figure 1 The secondary battery 10 shown includes: a wound electrode body 14 formed by winding a positive electrode 11 and a negative electrode 12 with a separator 13, a non-aqueous electrolyte, insulating plates 18a and 18b respectively disposed above and below the electrode body 14, and a battery casing 15 as an outer body. The battery casing 15 is composed of a casing body 16 that houses the electrode body 14, the non-aqueous electrolyte, etc., and a sealing body 17 that blocks the opening of the casing body 16. The battery casing 15 is not limited to a cylindrical or square metal casing; for example, it can also be a resin casing formed by laminating resin sheets (so-called laminated type).

[0027] Non-aqueous electrolytes, such as those with lithium-ion conductivity, can be liquid electrolytes (electrolytes) or solid electrolytes.

[0028] Liquid electrolytes (electrolytes) may include, for example, a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Examples of non-aqueous solvents include esters, ethers, nitriles, amides, and mixtures of two or more of these. Examples of non-aqueous solvents include ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and mixtures thereof. The non-aqueous solvent may contain halogen-substituted derivatives (e.g., fluoroethylene carbonate, etc.) formed by replacing at least a portion of the hydrogen atoms in these solvents with halogen atoms such as fluorine. Examples of electrolyte salts used include lithium salts such as LiPF6.

[0029] In addition, solid electrolytes can be, for example, solid or gel-like polymer electrolytes, inorganic solid electrolytes, etc. As inorganic solid electrolytes, materials known in all-solid-state lithium-ion secondary batteries (e.g., oxide-based solid electrolytes, sulfide-based solid electrolytes, halogen-based solid electrolytes, etc.) can be used. Polymer electrolytes may contain, for example, lithium salts and matrix polymers, or contain non-aqueous solvents, lithium salts and matrix polymers. As matrix polymers, polymer materials that gel by absorbing non-aqueous solvents can be used, for example. Examples of polymer materials include fluoropolymers, acrylic resins, polyether resins, etc. It should be noted that non-aqueous electrolytes are just one example; aqueous electrolytes can also be used, as long as they are applicable.

[0030] The outer casing 16 is, for example, a bottomed cylindrical metal container. A gasket 27 is provided between the outer casing 16 and the sealing body 17 to ensure the airtightness of the battery interior. The outer casing 16 has, for example, a protrusion 21 that bulges inward from a portion of its side surface and supports the sealing body 17. The protrusion 21 is preferably formed in a ring shape along the circumference of the outer casing 16, and supports the sealing body 17 on its upper surface.

[0031] The sealing body 17 has a structure in which a perforated metal plate 22, a lower valve body 23, an insulator 24, an upper valve body 25, and a cover 26 are stacked sequentially from the electrode body 14 side. Each component constituting the sealing body 17 has, for example, a circular or annular shape, and all components except the insulator 24 are electrically connected to each other. The lower valve body 23 and the upper valve body 25 are connected to each other at their respective central portions, and the insulator 24 is sandwiched between their respective peripheral portions. When the internal pressure of the secondary battery 10 rises due to heat generated by internal short circuits, for example, the lower valve body 23 deforms and breaks by pushing the upper valve body 25 towards the cover 26, cutting off the current path between the lower valve body 23 and the upper valve body 25. When the internal pressure rises further, the upper valve body 25 breaks, and gas is discharged from the opening of the cover 26.

[0032] exist Figure 1 In the secondary battery 10 shown, the positive electrode lead 19, mounted on the positive electrode 11, extends through a through hole in the insulating plate 18a toward the sealing body 17, and is connected to the lower surface of the perforated metal plate 22, which serves as the bottom plate of the sealing body 17, by welding or the like. Thus, the cover 26, which is electrically connected to the perforated metal plate 22, becomes the positive terminal of the sealing body 17. Furthermore, in Figure 1 In the secondary battery 10 shown, the negative electrode lead 20a, which is connected to the beginning winding end of the negative electrode 12, and the negative electrode lead 20b, which is connected to the end winding end of the negative electrode 12, extend towards the bottom side of the outer casing 16 through the insulating plate 18b, and are connected to the bottom inner surface of the outer casing 16 by welding or the like. Thus, the outer casing 16 becomes the negative terminal.

[0033] Figure 2 To show Figure 1 A schematic diagram of the inner end side of the winding direction of the electrode body with section AA. Figure 2 In the diagram, to easily understand the configuration relationship, solid lines represent negative electrode 12, dashed lines represent positive electrode 11, and single-dot dashed lines represent separator 13. Additionally, in... Figure 2 The gap between the positive electrode 11, the negative electrode 12, and the separator 13 is exaggerated in the diagram. The electrode body 14 is constructed by winding the positive electrode 11 and the negative electrode 12 with the separator 13 in between. The electrode body 14 is manufactured, for example, by stacking a strip-shaped positive electrode 11, a strip-shaped negative electrode 12, and a pair of strip-shaped separators 13 in the order of one separator 13, positive electrode 11, the other separator 13, and negative electrode 12, and then winding the stacked body into a spiral shape. In the electrode body 14, the long side direction of each electrode is the winding direction, and the width direction of each electrode is the winding axis direction.

[0034] like Figure 2 As shown, the negative electrode 12 has a non-opposing portion 40 on the initial winding end side, consisting of an outer peripheral non-opposing portion 44 and an inner peripheral non-opposing portion 46 separated by a separator 13 but not facing the positive electrode 11. Additionally, the negative electrode 12 has an insulating strip, which will be described later. Figure 2 Although the insulating tape is not shown in the diagram, it is disposed on the outer peripheral non-opposing portion 44 and the inner peripheral non-opposing portion 46. Additionally, the negative electrode 12 has an opposing portion 42 that faces the positive electrode 11 across the separator 13. The opposing portion 42 is wound around the non-opposing portion 40.

[0035] The non-opposing portion 40 has an outer peripheral non-opposing portion 44 and an inner peripheral non-opposing portion 46. It should be noted that the outer peripheral non-opposing portion 44 refers to the non-opposing portion located on the outer side in the radial direction of the wound negative electrode 12, and the inner peripheral non-opposing portion 46 refers to the non-opposing portion located on the inner side in the radial direction of the wound negative electrode 12. Figure 2 The non-opposing portion 40 shown (outer peripheral non-opposing portion 44 and inner peripheral non-opposing portion 46) starts from the beginning of the negative electrode 12. Figure 2 Point E1) is wound 1.5 turns. That is, the non-opposing portion 40 (outer peripheral non-opposing portion 44 and inner peripheral non-opposing portion 46) from Figure 2 Point E1 extends along the winding direction to point E2. The number of turns of the non-opposing portion 40 (outer peripheral non-opposing portion 44 and inner peripheral non-opposing portion 46) is, for example, 1.5 turns or more, preferably 1.5 turns or more and 3 turns or less.

[0036] Figure 3 This is a schematic cross-sectional view showing the state of the negative and positive electrodes at the beginning of winding before winding. (See attached image.) Figure 3 As shown, the negative electrode 12 has a negative electrode core 48 and a negative electrode composite material layer 50 disposed on the negative electrode core 48. The negative electrode composite material layer 50 may be formed on only one side of the negative electrode core 48 or on both sides of the negative electrode core 48. Figure 3 In the negative electrode 12 shown, the outer peripheral non-opposing portion 44 is composed of a negative electrode composite material layer 50 disposed on the negative electrode core 48 and an outer peripheral exposed portion 48a where the negative electrode composite material layer 50 is not disposed on the negative electrode core 48. However, it is not limited to this configuration. For example, it can be composed of either the negative electrode composite material layer 50 disposed on the negative electrode core 48 or the outer peripheral exposed portion 48a where the negative electrode composite material layer 50 is not disposed on the negative electrode core 48. Similarly, the inner peripheral non-opposing portion 46 is not limited to the case where it is composed of either the negative electrode composite material layer 50 disposed on the negative electrode core 48 or the inner peripheral exposed portion 48b where the negative electrode composite material layer 50 is not disposed on the negative electrode core 48. It can be composed of either the inner peripheral exposed portion 48b where the negative electrode composite material layer 50 is not disposed on the negative electrode core 48 or the negative electrode composite material layer 50 disposed on the negative electrode core 48.

[0037] The negative electrode 12 has a first insulating strip 52a disposed on the outer peripheral non-opposing portion 44 and a second insulating strip 52b disposed on the inner peripheral non-opposing portion 46. Figure 3 The first insulating strip 52a shown is disposed on the negative electrode composite material layer 50 within the outer peripheral non-opposing portion 44 and on the outer peripheral exposed portion 48a. It should be noted that the first insulating strip 52a may be disposed entirely or partially on the negative electrode composite material layer 50 within the outer peripheral non-opposing portion 44, or entirely or partially on the outer peripheral exposed portion 48a. Furthermore, Figure 3 The second insulating tape 52b shown is disposed on the negative electrode composite material layer 50 within the inner peripheral non-opposing portion 46 and on the inner peripheral exposed portion 48b. It should be noted that the second insulating tape 52b may be disposed entirely or partially on the negative electrode composite material layer 50 within the inner peripheral non-opposing portion 46, or entirely or partially on the inner peripheral exposed portion 48b.

[0038] When winding the negative electrode 12, the first insulating tape 52a is disposed on the outer peripheral non-opposing portion 44 in a range of 1.5 turns or more along the circumferential direction (i.e., the winding direction of the negative electrode 12). Furthermore, when winding the negative electrode 12, the second insulating tape 52b is disposed on the inner peripheral non-opposing portion 46 in a range of 0.9 turns or more along the circumferential direction (i.e., the winding direction of the negative electrode 12). Thus, with the first insulating tape 52a disposed in the outer peripheral non-opposing portion 44 in a range of 1.5 turns or more along the circumferential direction, and the second insulating tape 52b disposed in the outer peripheral non-opposing portion 44 in a range of 0.9 turns or more along the circumferential direction, even if the initial winding end of the negative electrode 12 is reinforced, or localized stress is applied to the center of the electrode body, the negative electrode 12 at the initial winding end can slide to alleviate the stress applied to the electrode, thereby suppressing electrode plate deformation during battery charging and discharging.

[0039] In terms of suppressing electrode plate deformation accompanied by charging and discharging, the first insulating strip 52a can be disposed on the outer peripheral non-opposing portion 44 within a range of 1.5 turns or more along the circumference of the outer peripheral non-opposing portion 44, but it is preferable to be disposed on the outer peripheral non-opposing portion 44 within a range of 1.5 turns or more and 3 turns or less.

[0040] For example, in suppressing electrode plate deformation during charging and discharging, the first insulating strip 52a can be disposed on the negative electrode composite material layer 50 within the outer peripheral non-opposing portion 44, or it can be disposed on the outer peripheral exposed portion 48a within the outer peripheral non-opposing portion 44, such as... Figure 3 As shown, it can also be disposed on both the outer peripheral exposed portion 48a within the outer peripheral non-opposing portion 44 and the negative electrode composite material layer 50.

[0041] Furthermore, when the first insulating strip 52a is disposed on at least the negative electrode composite material layer 50, for example, in terms of suppressing electrode plate deformation accompanied by charging and discharging, the area ratio of the first insulating strip 52a overlapping with the negative electrode composite material layer 50 in the outer peripheral non-opposing portion 44 is preferably 80% or more and 100% or less.

[0042] For example, in suppressing electrode deformation accompanying charging and discharging, such as Figure 3 As shown, the first insulating strip 52a is preferably disposed on the outer peripheral non-opposing portion 44 starting from the circumferential inner end edge 44a of the outer peripheral non-opposing portion 44. It should be noted that the first insulating strip 52a may also extend from the outer peripheral non-opposing portion 44 and be disposed on the outer peripheral opposing portion, but for example, in terms of battery capacity, it is preferable not to be disposed on the outer peripheral opposing portion.

[0043] In terms of suppressing electrode plate deformation accompanied by charging and discharging, the second insulating tape 52b only needs to be disposed on the inner peripheral non-opposing portion 46 within a range of 0.9 turns or more along the circumference of the inner peripheral non-opposing portion 46, but preferably the area ratio of overlapping with the inner peripheral non-opposing portion 46 is 50% or more and 100% or less.

[0044] For example, in suppressing electrode plate deformation during charging and discharging, the second insulating strip 52b can be disposed on the negative electrode composite material layer 50 within the inner peripheral non-opposing portion 46, or it can be disposed on the inner peripheral exposed portion 48b within the inner peripheral non-opposing portion 46, such as... Figure 3 As shown, it can also be disposed on both the inner peripheral exposed portion 48b within the inner peripheral non-opposing portion 46 and the negative electrode composite material layer 50.

[0045] For example, in suppressing electrode deformation accompanying charging and discharging, such as Figure 3As shown, the second insulating tape 52b is preferably disposed on the inner circumferential non-opposing portion 46, starting from the inner circumferential inner end edge 46a of the inner circumferential non-opposing portion 46. It should be noted that the second insulating tape 52b may also extend from the inner circumferential non-opposing portion 46 and be disposed on the opposing portion of the inner circumferential side, but for example, in terms of battery capacity, it is preferable not to be disposed on the opposing portion of the inner circumferential side.

[0046] Figure 4 This is a schematic cross-sectional view illustrating an example of the structure of the insulating tape. The insulating tape 52 described below applies to the first insulating tape 52a and the second insulating tape 52b described above. The insulating tape 52 includes, for example, a substrate layer 54 and an adhesive layer 56. The insulating tape 52 has a laminated structure in which the adhesive layer 56 and the substrate layer 54 are sequentially stacked from the non-opposing side. For example, in terms of flexibility and strength, the thickness of the insulating tape 52 is preferably 0.02 mm or more and 0.1 mm or less.

[0047] For example, in terms of insulation, electrolyte resistance, heat resistance, and strength, the substrate layer 54 preferably contains a resin. The resin content, for example, can be 90% by mass or more, 95% by mass or more, or 100% by mass relative to the total mass of the substrate layer 54. Examples of resins include polyolefins (e.g., polyethylene, polypropylene, etc.), polystyrene, polyesters (e.g., polyethylene terephthalate, etc.), polyimides, polyamides, polyamide-imides, polycarbonates, and polyphenylene sulfides. One of these resins can be used alone, or two or more can be used in combination. Among these resins, polypropylene is preferred, for example, for improving the flexibility of the insulating tape 52. The polypropylene content, for example, can be 50% by mass or more, 80% by mass or more, or 100% by mass relative to the total mass of the resin contained in the substrate layer 54.

[0048] The adhesive layer 56 is primarily used to impart adhesion to the insulating tape 52 to the negative electrode 12. The adhesive layer 56 is formed by applying an adhesive to one surface of the substrate layer 54. The adhesive constituting the adhesive layer 56 can be a hot-melt type that exhibits adhesion upon heating or a thermosetting type that cures upon heating; however, from the perspective of productivity, an adhesive that exhibits adhesion at room temperature is preferred. Examples of adhesives include acrylic adhesives and synthetic rubber adhesives.

[0049] Insulating tape 52 is not limited to Figure 4The illustrated configuration could also be a configuration where an inorganic particle-containing layer exists between the substrate layer 54 and the adhesive layer 56. This inorganic particle-containing layer, for example, has a structure in which inorganic particles are dispersed in a resin matrix constituting the layer. The inorganic particle-containing layer is formed, for example, by coating one surface of the substrate layer 54 with a resin solution containing inorganic particles. Examples of inorganic particles include metal oxide particles, metal nitride particles, metal fluoride particles, and metal carbide particles. Examples of resin matrices include acrylic resins, urethane resins, and their elastomers.

[0050] The negative electrode core 48 constituting the negative electrode 12 can be made of a foil of a metal that is stable within the potential range of the negative electrode, such as copper or a copper alloy, or a thin film of such metal disposed on the surface. The thickness of the negative electrode core 48 is, for example, in the range of 7 μm to 50 μm.

[0051] Furthermore, the negative electrode composite material layer 50 constituting the negative electrode 12 includes, for example, a negative electrode active material and a binder. The thickness of the negative electrode composite material layer 50 is, for example, in the range of 10 μm to 100 μm. The negative electrode composite material layer 50 can be manufactured, for example, by coating a negative electrode composite material slurry containing a negative electrode active material and a binder onto the negative electrode core 48, drying the coating, and then calendering it.

[0052] The negative electrode active material contained in the negative electrode composite layer 50 is not particularly limited to any material capable of reversibly absorbing and releasing lithium ions; examples include carbon materials and Si-based materials. For increasing battery capacity, the negative electrode active material preferably includes Si-based materials.

[0053] Carbon materials can be, for example, previously known carbon materials used as negative electrode active materials, such as natural graphite such as flake graphite, block graphite, and amorphous graphite; and artificial graphite such as blocky graphite (MAG) and graphitized mesophase carbon microspheres (MCMB).

[0054] As a Si-based material, any material capable of reversibly absorbing and releasing lithium ions is acceptable, without particular limitations. Examples include Si particles, Si-containing alloy particles, and Si compound particles. Among these, Si compound particles are preferred.

[0055] Examples of Si compound particles include Si compound particles having a silicate phase and Si particles dispersed in the silicate phase, Si compound particles having a silicon oxide phase and Si particles dispersed in the silicon oxide phase, and Si compound particles having a carbon phase and Si particles dispersed in the carbon phase.

[0056] From the perspective of high lithium-ion conductivity, the silicate phase preferably contains at least one element selected from lithium, sodium, potassium, rubidium, cesium, francium, beryllium, magnesium, calcium, strontium, barium, and radium. Among these, from the perspective of high lithium-ion conductivity, the silicate phase is preferably a silicate phase containing lithium (hereinafter sometimes referred to as lithium silicate phase).

[0057] Lithium silicate phase, for example, is represented by the formula: Li 2z SiO 2+z (0 < z < 2) indicates that, from the perspectives of stability, ease of manufacture, and lithium-ion conductivity, z preferably satisfies the relationship 0 < z < 1, and more preferably z = 1 / 2.

[0058] Si particles are Si compound particles dispersed in a silicon oxide phase, such as those of the general formula SiO. x (Preferably in the range of 0 < x < 2, more preferably in the range of 0.5 ≤ x ≤ 1.6) represents the Si compound particles dispersed in the carbon phase, for example, those of the general formula Si. x C1 y (Preferably, the ranges of 0 < x ≤ 1 and 0 < y ≤ 1 are preferred, and more preferably the ranges of 0.3 ≤ x ≤ 0.45 and 0.7 ≤ y ≤ 0.55 are preferred.)

[0059] The surface of Si-based material particles preferably has a conductive coating made of a highly conductive material. Examples of conductive coatings include carbon coatings, metal coatings, and metal compound coatings, but carbon coatings are preferred from the perspective of electrochemical stability. Carbon coatings can be formed, for example, by using CVD methods with acetylene, methane, etc., or by mixing coal tar pitch, petroleum pitch, phenolic resin, etc., with a silicon-based active material and then heat-treating the mixture. Alternatively, a conductive coating can be formed by using a binder to fix conductive fillers such as carbon black onto the surface of Si-based material particles.

[0060] From the perspective of increasing battery capacity, the content of Si-based materials is preferably 5% by mass or more relative to the total mass of the negative electrode composite material layer 50.

[0061] Besides carbon and Si-based materials, negative electrode active materials can also include other materials capable of reversibly absorbing and releasing lithium ions. Examples of such other materials include Sn, Sn-containing alloys, tin oxide, and other Sn-based materials; and lithium titanate and other Ti-based materials.

[0062] Examples of adhesives include fluorinated resins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyimide resins, acrylic resins, polyolefin resins, styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC) or its salts, polyacrylic acid (PAA) or its salts, polyvinyl alcohol (PVA), and polyethylene oxide (PEO).

[0063] The positive electrode 11 has a positive electrode core and a positive electrode composite material layer formed on the surface of the positive electrode core. The positive electrode composite material layer is preferably formed on both sides of the positive electrode core. As the positive electrode core, a foil of a metal stable within the potential range of the positive electrode 11, such as aluminum, or a thin film with the metal disposed on the surface, can be used. The positive electrode composite material layer includes, for example, a positive electrode active material, a binder, and a conductive agent. The positive electrode composite material layer can be manufactured, for example, by coating the positive electrode core with a positive electrode composite material slurry containing a positive electrode active material, a binder, and a conductive agent, drying the coating, and then calendering it.

[0064] Examples of positive electrode active materials included in the positive electrode composite layer include lithium transition metal oxides containing transition metal elements such as Co, Mn, and Ni. Lithium transition metal oxides are, for example, Li. x CoO2, Li x NiO2, Li x MnO2, Li x Co y Ni 1- y O2, Li x Co y M 1-y O z Li x Ni 1-y M y O z Li x Mn2O4, Li x Mn 2-y M y O4, LiMPO4, and Li2MPO4F (M is at least one of Na, Mg, Sc, Y, Mn, Fe, Co, Ni, Cu, Zn, Al, Cr, Pb, Sb, and B, where 0 < x ≤ 1.2, 0 < y ≤ 0.9, and 2.0 ≤ z ≤ 2.3). They can be used individually or in combination. From the perspective of achieving high battery capacity, the positive electrode active material preferably contains Li. x NiO2, Li x CoyNi 1-y O2, Li x Ni 1-y M y O z (M is at least one of Na, Mg, Sc, Y, Mn, Fe, Co, Ni, Cu, Zn, Al, Cr, Pb, Sb, and B, with 0 < x ≤ 1.2, 0 < y ≤ 0.9, and 2.0 ≤ z ≤ 2.3) and other lithium-nickel composite oxides. The surface of the lithium transition metal oxide particles may be bonded with inorganic particles such as tungsten oxide, aluminum oxide, or lanthanide compounds.

[0065] Examples of conductive agents contained in the positive electrode composite layer include carbon materials such as carbon black (CB), acetylene black (AB), Ketjen black, carbon nanotubes (CNT), graphene, and graphite. Examples of binders contained in the positive electrode composite layer are the same as those used in the negative electrode 12.

[0066] As the separator 13, a porous sheet with ion permeability and insulation properties can be used, for example. Specific examples of porous sheets include microporous films, woven fabrics, and nonwoven fabrics. The material of the separator is preferably olefin resins such as polyethylene and polypropylene, or cellulose. The separator 13 can also be a laminate having a cellulose fiber layer and a thermoplastic resin fiber layer such as an olefin resin. In addition, a multilayer separator containing a polyethylene layer and a polypropylene layer can be used, or a separator with an aromatic polyamide resin, ceramic, or other material coated on the surface of the separator 13 can be used.

[0067] Example

[0068] The present disclosure will be further illustrated below by way of examples, but the present disclosure is not limited to these examples.

[0069] <Example 1>

[0070] [The production of the positive electrode]

[0071] 100 parts by weight of LiNi 0.88 Co 0.09 Al 0.03 O2, 1 part by mass of acetylene black (AB), and 0.9 parts by mass of polyvinylidene fluoride (PVDF) were mixed, and an appropriate amount of N-methyl-2-pyrrolidone (NMP) was added to prepare a positive electrode composite slurry. Next, the positive electrode composite slurry was coated onto both sides of a 15 μm thick aluminum foil and allowed to dry. Then, the coating was calendered using rollers and cut into specified electrode sizes to fabricate a positive electrode with positive electrode composite layers formed on both sides of the positive electrode core. An exposed portion without a positive electrode composite layer on the positive electrode core was provided at the center of the long side of the positive electrode, and an aluminum positive electrode lead was welded to this exposed portion.

[0072] [Making the negative electrode]

[0073] A dispersion of 92 parts by weight of graphite powder, 6 parts by weight of Si-based material, 1 part by weight of sodium carboxymethyl cellulose (CMC-Na), and 1 part by weight of styrene-butadiene rubber (SBR) was mixed, and an appropriate amount of water was added to prepare a negative electrode composite slurry. Next, the negative electrode composite slurry was coated onto both sides of an 8 μm thick copper foil, and the coating was allowed to dry. Then, the coating was calendered using a roller and cut into specified electrode sizes to create a negative electrode with a negative electrode composite layer formed on both sides of the negative electrode core. Exposed portions without a negative electrode composite layer were provided at both ends of the long side of the negative electrode, and nickel negative electrode leads were welded to these exposed portions. Additionally, an insulating tape was placed at the end of the negative electrode that forms the starting winding side. As the insulating tape, an acrylic adhesive tape coated on a polypropylene substrate was used. The placement of the insulating tape in Example 1 will be described below.

[0074] Figure 5 This is a schematic cross-sectional view showing the state of the negative and positive electrodes at the beginning of winding before winding in Embodiment 1. In Embodiment 1, a first insulating strip 52a is disposed on the outer peripheral exposed portion 48a within the outer peripheral non-opposing portion 44 of the negative electrode 12 and on the negative electrode composite material layer 50. Additionally, a second insulating strip 52b is disposed on the negative electrode composite material layer 50 within the inner peripheral non-opposing portion 46 of the negative electrode 12. When winding the negative electrode 12, the first insulating strip 52a disposed on the outer peripheral non-opposing portion 44 is disposed within a circumferential range of 2.1 turns in the outer peripheral non-opposing portion 44 (number of turns of insulating strip: 2.1 turns). Furthermore, the area ratio of the first insulating strip 52a disposed on the outer peripheral non-opposing portion 44 overlapping with the outer peripheral exposed portion 48a within the outer peripheral non-opposing portion 44 is 100%, and the area ratio of the first insulating strip 52a overlapping with the negative electrode composite material layer 50 within the outer peripheral non-opposing portion 44 is 94%. On the other hand, when winding the negative electrode 12, the second insulating tape 52b disposed on the inner circumferential non-opposing portion 46 of the negative electrode 12 is disposed within a range of 0.9 turns in the circumferential direction of the inner circumferential non-opposing portion 46 (number of turns of the insulating tape: 0.9 turns). In addition, the area ratio of the second insulating tape 52b disposed on the inner circumferential non-opposing portion 46 overlapping with the inner circumferential non-opposing portion 46 is 50%, and the area ratio of the second insulating tape 52b overlapping with the inner circumferential exposed portion 48b within the inner circumferential non-opposing portion 46 is 0%.

[0075] [Preparation of non-aqueous electrolytes]

[0076] A non-aqueous electrolyte was prepared by adding 5 parts by mass of vinylene carbonate (VC) to 100 parts by mass of a mixed solvent of ethylene carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 3:7, and dissolving lithium hexafluoride phosphate (LiPF6) at a concentration of 1.5 mol / L.

[0077] [Construction of a non-aqueous electrolyte secondary battery]

[0078] A wound electrode body is fabricated by winding the aforementioned positive and negative electrodes with a separator between them. Insulating plates are placed above and below the electrode body, and the electrode body is housed within the outer casing. The negative electrode lead is soldered to the bottom of the outer casing, and the positive electrode lead is soldered to the sealing body. After injecting a non-aqueous electrolyte into the outer casing, the opening of the outer casing is sealed with the sealing body using a gasket, thus fabricating a non-aqueous electrolyte secondary battery.

[0079] <Example 2>

[0080] Figure 6 This is a schematic cross-sectional view showing the state of the negative and positive electrodes at the beginning of winding before winding in Embodiment 2. In Embodiment 2, a first insulating strip 52a is disposed on the outer peripheral exposed portion 48a within the outer peripheral non-opposing portion 44 of the negative electrode 12 and on the negative electrode composite material layer 50. Additionally, a second insulating strip 52b is disposed on the inner peripheral exposed portion 48b within the inner peripheral non-opposing portion 46 of the negative electrode 12. The arrangement of the first insulating strip 52a on the outer peripheral non-opposing portion 44 is the same as in Embodiment 1. On the other hand, when winding the negative electrode 12, the second insulating strip 52b disposed on the inner peripheral non-opposing portion 46 of the negative electrode 12 is arranged circumferentially within the inner peripheral non-opposing portion 46 within a range of 1.2 turns (number of turns of insulating strip: 1.2 turns). Furthermore, the area ratio of the second insulating strip 52b disposed on the inner peripheral side non-opposing portion 46 to the inner peripheral side non-opposing portion 46 is 53%, and the area ratio of the second insulating strip 52b to the inner peripheral side exposed portion 48b within the inner peripheral side non-opposing portion 46 is 100%. Except for using the above-described negative electrode, a non-aqueous electrolyte secondary battery is manufactured in the same manner as in Example 1.

[0081] <Example 3>

[0082] Figure 7This is a schematic cross-sectional view showing the state of the negative and positive electrodes at the beginning of winding before winding in Embodiment 3. In Embodiment 3, a first insulating strip 52a is disposed on the outer peripheral exposed portion 48a within the outer peripheral non-opposing portion 44 of the negative electrode 12 and on the negative electrode composite material layer 50. Additionally, a second insulating strip 52b is disposed on the inner peripheral exposed portion 48b within the inner peripheral non-opposing portion 46 of the negative electrode 12 and on the negative electrode composite material layer 50. The arrangement of the first insulating strip 52a on the outer peripheral non-opposing portion 44 is the same as in Embodiment 1. On the other hand, when winding the negative electrode 12, the second insulating strip 52b disposed on the inner peripheral non-opposing portion 46 of the negative electrode 12 is disposed within a range of 2.1 turns circumferentially in the inner peripheral non-opposing portion 46 (number of turns of insulating strip: 2.1 turns). Furthermore, the area ratio of the second insulating strip 52b disposed on the inner peripheral side non-opposing portion 46 to the inner peripheral side non-opposing portion 46 is 97%, and the area ratio of the second insulating strip 52b to the inner peripheral side exposed portion 48b within the inner peripheral side non-opposing portion 46 is 100%. Except for using the above-described negative electrode, a non-aqueous electrolyte secondary battery is manufactured in the same manner as in Example 1.

[0083] <Comparative Example 1>

[0084] Figure 8 This is a schematic cross-sectional view showing the state of the negative and positive electrodes at the beginning of winding before winding in Comparative Example 1. In Comparative Example 1, a first insulating strip 52a is disposed on the outer peripheral exposed portion 48a within the outer peripheral non-opposing portion 44 of the negative electrode 12 and on the negative electrode composite material layer 50. When winding the negative electrode 12, the first insulating strip 52a disposed on the outer peripheral non-opposing portion 44 of the negative electrode 12 is disposed within a range of 1.0 turns circumferentially in the outer peripheral non-opposing portion 44 (number of turns of insulating strip: 1.0 turn). In addition, the area ratio of the first insulating strip 52a disposed on the outer peripheral non-opposing portion 44 overlapping with the outer peripheral exposed portion 48a within the outer peripheral non-opposing portion 44 is 100%, and the area ratio of the first insulating strip 52a overlapping with the negative electrode composite material layer 50 within the outer peripheral non-opposing portion 44 is 13%. Except for using the above-described negative electrode, a non-aqueous electrolyte secondary battery is manufactured in the same manner as in Example 1.

[0085] <Comparative Example 2>

[0086] Figure 9 This is a schematic cross-sectional view showing the state of the negative and positive electrodes at the beginning of winding before winding in Comparative Example 2. In Comparative Example 2, a first insulating strip 52a is disposed on the outer peripheral exposed portion 48a within the outer peripheral non-opposing portion 44 of the negative electrode 12 and on the negative electrode composite material layer 50. The arrangement of the first insulating strip 52a on the outer peripheral non-opposing portion 44 is the same as in Example 1. Except for using the aforementioned negative electrode, a non-aqueous electrolyte secondary battery is manufactured in the same manner as in Example 1.

[0087] <Comparative Example 3>

[0088] Figure 10 This is a schematic cross-sectional view showing the state of the negative and positive electrodes at the beginning of winding before winding in Comparative Example 3. In Comparative Example 3, a first insulating tape 52a is disposed on the exposed portion 48a of the outer peripheral side of the negative electrode 12 within the outer peripheral side non-opposing portion 44. Furthermore, a second insulating tape 52b is disposed on the exposed portion 48b of the inner peripheral side non-opposing portion 46 of the negative electrode 12 and on the negative electrode composite material layer 50. When winding the negative electrode 12, the first insulating tape 52a disposed on the outer peripheral side non-opposing portion 44 is disposed within a range of 1.2 turns circumferentially in the outer peripheral side non-opposing portion 44 (number of turns of insulating tape: 1.2 turns). Furthermore, the area ratio of the first insulating tape 52a disposed on the outer peripheral side non-opposing portion 44 overlapping with the exposed portion 48a of the outer peripheral side non-opposing portion 44 is 100%, and the area ratio of the first insulating tape 52a overlapping with the negative electrode composite material layer 50 of the outer peripheral side non-opposing portion 44 is 0%. On the other hand, when winding the negative electrode 12, the second insulating tape 52b disposed on the inner peripheral non-opposing portion 46 of the negative electrode 12 is disposed within a range of 2.1 turns in the circumferential direction of the inner peripheral non-opposing portion 46 (number of turns of the insulating tape: 2.1 turns). In addition, the area ratio of the second insulating tape 52b disposed on the inner peripheral non-opposing portion 46 overlapping with the inner peripheral non-opposing portion 46 is 97%, and the area ratio of the second insulating tape 52b overlapping with the inner peripheral exposed portion 48b within the inner peripheral non-opposing portion 46 is 100%.

[0089] <Comparative Example 4>

[0090] Figure 11This is a schematic cross-sectional view showing the state of the negative and positive electrodes at the beginning of winding before winding in Comparative Example 4. In Comparative Example 4, a first insulating tape 52a is disposed on the negative electrode composite material layer 50 within the outer peripheral non-opposing portion 44 of the negative electrode 12. Additionally, a second insulating tape 52b is disposed on the inner peripheral exposed portion 48b within the inner peripheral non-opposing portion 46 of the negative electrode 12 and on the negative electrode composite material layer 50. When winding the negative electrode 12, the first insulating tape 52a disposed on the outer peripheral non-opposing portion 44 is disposed within a circumferential range of 0.9 turns in the outer peripheral non-opposing portion 44 (number of turns of insulating tape: 0.9 turns). Furthermore, the area ratio of the first insulating tape 52a disposed on the outer peripheral non-opposing portion 44 overlapping with the outer peripheral exposed portion 48a within the outer peripheral non-opposing portion 44 is 0%, and the area ratio of the first insulating tape 52a overlapping with the negative electrode composite material layer 50 within the outer peripheral non-opposing portion 44 is 94%. On the other hand, when winding the negative electrode 12, the second insulating tape 52b disposed on the inner peripheral non-opposing portion 46 of the negative electrode 12 is disposed within a range of 2.1 turns in the circumferential direction of the inner peripheral non-opposing portion 46 (number of turns of the insulating tape: 2.1 turns). In addition, the area ratio of the second insulating tape 52b disposed on the inner peripheral non-opposing portion 46 overlapping with the inner peripheral non-opposing portion 46 is 97%, and the area ratio of the second insulating tape 52b overlapping with the inner peripheral exposed portion 48b within the inner peripheral non-opposing portion 46 is 100%.

[0091] [Evaluation of plate deformation]

[0092] The non-aqueous electrolyte secondary batteries of each embodiment and comparative example were charged with a constant current of 0.3 It until the battery voltage reached 4.2V, and then charged with a constant voltage of 4.2V until the current reached 0.02 It. Then, they were discharged with a constant current of 1.0 It until the battery voltage reached 2.7V. The cross-section of the center portion of the electrode body of the non-aqueous electrolyte secondary battery was observed using an X-ray CT apparatus (Shimadzu SMX-225CT FPD HR) to confirm whether any electrode deformation had occurred. The results are summarized in Table 1.

[0093] [Table 1]

[0094]

[0095] In Comparative Examples 1-4, electrode deformation was confirmed, but in Examples 1-3, electrode deformation was not confirmed. Based on this result, it can be concluded that, as in the examples, by arranging the first insulating strip on the outer peripheral non-opposing portion of the negative electrode in a circumferential direction of at least 1.5 turns, and arranging the second insulating strip on the inner peripheral non-opposing portion of the negative electrode in a circumferential direction of at least 0.9 turns, the occurrence of electrode deformation accompanying charging and discharging can be suppressed.

[0096] [Postscript] (1)

[0098] A secondary battery, characterized in that it has an electrode body formed by winding a positive electrode and a negative electrode having a negative electrode composite material layer disposed on a negative electrode core, separated by a separator.

[0099] The negative electrode has an outer peripheral non-opposing portion and an inner peripheral non-opposing portion at the beginning winding end, which are separated by the separator but not opposite to the positive electrode, and has a first insulating strip disposed on the outer peripheral non-opposing portion and a second insulating strip disposed on the inner peripheral non-opposing portion.

[0100] The first insulating tape is disposed on the outer peripheral non-opposing portion within a range of 1.5 turns or more along the circumference of the outer peripheral non-opposing portion.

[0101] The second insulating tape is disposed on the non-opposite portion of the inner circumference side within a range of more than 0.9 turns along the circumference of the non-opposite portion of the inner circumference side. (2)

[0103] According to the secondary battery described in (1) above, wherein,

[0104] The first insulating tape is disposed on the non-opposite portion of the outer periphery within a range of 1.5 turns to 3 turns along the circumference of the non-opposite portion of the outer periphery. (3)

[0106] According to the secondary battery described in (1) or (2) above, wherein,

[0107] The area ratio of the overlap between the first insulating strip and the negative electrode composite material layer in the non-opposing portion on the outer periphery is more than 80% and less than 100%. (4)

[0109] The secondary battery according to any one of (1) to (3) above, wherein,

[0110] The outer peripheral non-opposing portion has an outer peripheral exposed portion where no negative electrode composite material layer is formed on the negative electrode core.

[0111] The first insulating tape is disposed on the exposed portion on the outer periphery. (5)

[0113] The secondary battery according to any one of (1) to (4) above, wherein,

[0114] The area ratio of the overlap between the second insulating strip and the non-opposing portion on the inner periphery is more than 50% and less than 100%. (6)

[0116] According to any one of (1) to (5) above, the secondary battery, wherein,

[0117] The second insulating strip is disposed on the negative electrode composite material layer in the non-opposing portion of the inner circumferential side. (7)

[0119] According to any one of (1) to (6) above, the secondary battery, wherein,

[0120] The non-opposing portion on the inner circumferential side has an exposed portion on the inner circumferential side where no negative electrode composite material layer is formed on the negative electrode core.

[0121] The second insulating tape is disposed on the exposed portion on the inner circumferential side. (8)

[0123] The secondary battery according to any one of (1) to (7) above, wherein,

[0124] The non-opposing portion on the inner circumferential side has an exposed portion on the inner circumferential side where no negative electrode composite material layer is formed on the negative electrode core.

[0125] The second insulating strip is disposed on the negative electrode composite material layer in the non-opposing portion of the inner circumference and on the exposed portion of the inner circumference. (9)

[0127] According to any one of (1) to (8) above, the secondary battery, wherein,

[0128] The first insulating strip is disposed on the non-opposite portion of the outer periphery, starting from the inner edge of the outer periphery side. (10)

[0130] According to any one of (1) to (9) above, the secondary battery, wherein,

[0131] The second insulating strip is disposed on the non-opposing portion of the inner circumferential side, starting from the inner edge of the inner circumferential side. (11)

[0133] The secondary battery according to any one of (1) to (10) above, wherein,

[0134] The first insulating tape has a laminated structure in which an adhesive layer and a substrate layer are stacked sequentially from the outer peripheral side (non-opposing portion), and the second insulating tape has a laminated structure in which an adhesive layer and a substrate layer are stacked sequentially from the inner peripheral side (non-opposing portion). (12)

[0136] According to the secondary battery described in (11) above, wherein,

[0137] The substrate layer comprises polypropylene. (13)

[0139] The secondary battery according to any one of (1) to (12) above, wherein,

[0140] The thicknesses of the first insulating tape and the second insulating tape are respectively 0.02 mm or more and 0.1 mm or less.

[0141] Explanation of reference numerals in the attached figures

[0142] 10: Secondary battery; 11: Positive electrode; 12: Negative electrode; 13: Separator; 14: Electrode body; 15: Battery casing; 16: Casing body; 17: Sealing body; 18a, 18b: Insulating plate; 19: Positive electrode lead; 20a, 20b: Negative electrode lead; 21: Protrusion; 22: Perforated metal plate; 23: Lower valve body; 24: Insulator; 25: Upper valve body; 26: Cover; 27: Pad 40: Non-opposing portion; 42: Opposing portion; 44: Outer peripheral non-opposing portion; 44a, 46a: Circumferential inner edge; 46: Inner peripheral non-opposing portion; 48: Negative electrode core; 48a: Outer peripheral exposed portion; 48b: Inner peripheral exposed portion; 50: Negative electrode composite material layer; 52: Insulating tape; 52a: First insulating tape; 52b: Second insulating tape; 54: Substrate layer; 56: Adhesive layer.

Claims

1. A secondary battery, characterized in that, It has an electrode body consisting of a positive electrode and a negative electrode with a negative electrode composite material layer disposed on the negative electrode core, wound together with a separator. The negative electrode has an outer peripheral non-opposing portion and an inner peripheral non-opposing portion at the beginning winding end, which are separated by the separator but not opposite to the positive electrode, and has a first insulating strip disposed on the outer peripheral non-opposing portion and a second insulating strip disposed on the inner peripheral non-opposing portion. The first insulating tape is disposed on the outer peripheral non-opposing portion within a range of 1.5 turns or more along the circumference of the outer peripheral non-opposing portion. The second insulating tape is disposed on the non-opposite portion of the inner circumference side within a range of more than 0.9 turns along the circumference of the non-opposite portion of the inner circumference side.

2. The secondary battery according to claim 1, wherein, The first insulating tape is disposed on the non-opposite portion of the outer periphery within a range of 1.5 turns to 3 turns along the circumference of the non-opposite portion of the outer periphery.

3. The secondary battery according to claim 1 or 2, wherein, The area ratio of the overlap between the first insulating strip and the negative electrode composite material layer in the non-opposing portion on the outer periphery is more than 80% and less than 100%.

4. The secondary battery according to claim 1 or 2, wherein, The outer peripheral non-opposing portion has an outer peripheral exposed portion where no negative electrode composite material layer is formed on the negative electrode core. The first insulating tape is disposed on the exposed portion on the outer periphery.

5. The secondary battery according to claim 1 or 2, wherein, The area ratio of the overlap between the second insulating strip and the non-opposing portion on the inner periphery is more than 50% and less than 100%.

6. The secondary battery according to claim 1 or 2, wherein, The second insulating strip is disposed on the negative electrode composite material layer in the non-opposing portion of the inner circumferential side.

7. The secondary battery according to claim 1 or 2, wherein, The non-opposing portion on the inner circumferential side has an exposed portion on the inner circumferential side where no negative electrode composite material layer is formed on the negative electrode core. The second insulating tape is disposed on the exposed portion on the inner circumferential side.

8. The secondary battery according to claim 1 or 2, wherein, The non-opposing portion on the inner circumferential side has an exposed portion on the inner circumferential side where no negative electrode composite material layer is formed on the negative electrode core. The second insulating strip is disposed on the negative electrode composite material layer in the non-opposing portion of the inner circumference and on the exposed portion of the inner circumference.

9. The secondary battery according to claim 1 or 2, wherein, The first insulating strip is disposed on the non-opposite portion of the outer periphery, starting from the inner edge of the outer periphery side.

10. The secondary battery according to claim 1 or 2, wherein, The second insulating strip is disposed on the non-opposing portion of the inner circumferential side, starting from the inner edge of the inner circumferential side.

11. The secondary battery according to claim 1 or 2, wherein, The first insulating tape has a laminated structure in which an adhesive layer and a substrate layer are stacked sequentially from the outer peripheral side (non-opposing portion), and the second insulating tape has a laminated structure in which an adhesive layer and a substrate layer are stacked sequentially from the inner peripheral side (non-opposing portion).

12. The secondary battery according to claim 11, wherein, The substrate layer comprises polypropylene.

13. The secondary battery according to claim 1 or 2, wherein, The thicknesses of the first insulating tape and the second insulating tape are respectively 0.02 mm or more and 0.1 mm or less.

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