Non-aqueous electrolyte secondary battery

Abstract

A first electrode (11) comprising a first electrode core body (30) and a first electrode mixture layer (31), wherein, at one end in the width direction of the first electrode (11), a mixture layer-free portion (32) is provided on which the first electrode mixture layer (31) is not disposed on the first electrode core body (30); the mixture layer-free portion (32) has an insulating layer forming portion (33) in which an insulating layer is provided on the first electrode core body (30) and a core body exposed portion (34) which is provided to the one side in the width direction of the first electrode (11) relative to the insulating layer forming portion (33) and from which the first electrode core body (30) is exposed, and is characterized in that the first electrode (11) is bent in the radial direction starting from the boundary portion between the insulating layer forming portion (33) and the core body exposed portion (34), and the width of the insulating layer forming portion (33) differs in the longitudinal direction of the first electrode (11).

Description

Nonaqueous electrolyte secondary battery

[0001] This disclosure relates to a non-aqueous electrolyte secondary battery.

[0002] Non-aqueous electrolyte secondary batteries have been known for some time, comprising an electrode body in which a strip-shaped positive electrode and a strip-shaped negative electrode are wound with a separator in between, a non-aqueous electrolyte, and an outer container that houses the electrode body and the non-aqueous electrolyte. Generally, the positive electrode includes a positive electrode core and a positive electrode mixture layer disposed on the positive electrode core, and the negative electrode includes a negative electrode core and a negative electrode mixture layer disposed on the negative electrode core.

[0003] From the viewpoint of improving the output characteristics of non-aqueous electrolyte secondary batteries, a technique is known in which a non-compound layer is formed at both axial ends of the electrode body, exposing the positive electrode core and the negative electrode core, and the non-compound layer is bent radially and joined to a current collector plate or outer casing (see, for example, Patent Document 1). In addition, an insulating layer may be formed on a part of the non-compound layer to suppress internal short circuits, etc.

[0004] Japanese Patent Publication No. 2000-77054

[0005] As described in Patent Document 1, in a non-aqueous electrolyte secondary battery in which a portion of the non-compound layer formation area is bent radially and welded to a current collector plate or the like, the injection path of the non-aqueous electrolyte is easily obstructed by the non-compound layer formation area when injecting the non-aqueous electrolyte into the outer casing. As a result, it may take time for the non-aqueous electrolyte to penetrate into the inside of the electrode body. From the viewpoint of realizing a highly productive non-aqueous electrolyte secondary battery, there is a need to shorten the injection time of the non-aqueous electrolyte.

[0006] A non-aqueous electrolyte secondary battery according to one aspect of the present disclosure comprises an electrode body in which a first electrode and a second electrode having opposite polarities are wound longitudinally via a separator, a non-aqueous electrolyte, and an outer container for housing the electrode body and the non-aqueous electrolyte, wherein the first electrode has a first electrode core and a first electrode mixture layer disposed on the first electrode core, and a non-composite mixture layer portion is provided at one end of the first electrode in the width direction, wherein the non-composite mixture layer portion has an insulating layer forming portion on the first electrode core and a core body exposed portion provided on one side of the first electrode in the width direction from the insulating layer forming portion, wherein the first electrode core is exposed, and is bent radially starting from the boundary between the insulating layer forming portion and the core body exposed portion, and the width of the insulating layer forming portion differs in the longitudinal direction of the first electrode.

[0007] According to one aspect of this disclosure, a non-aqueous electrolyte secondary battery can be realized, which offers high productivity.

[0008] This is an axial cross-sectional view of the non-aqueous electrolyte secondary battery of the first embodiment. This is a perspective view of the electrode body provided in the non-aqueous electrolyte secondary battery of the first embodiment. This is an enlarged view of the upper part of the electrode body in Figure 1. This is a plan view showing the positive electrode of the first embodiment in an unfolded state. This is a diagram corresponding to Figure 3 in the non-aqueous electrolyte secondary battery of the second embodiment. This is a diagram corresponding to Figure 4 in the non-aqueous electrolyte secondary battery of the second embodiment. This is a diagram corresponding to Figure 3 in the non-aqueous electrolyte secondary battery of the third embodiment. This is a diagram corresponding to Figure 4 in the non-aqueous electrolyte secondary battery of the third embodiment. This is a diagram corresponding to Figure 3 in the non-aqueous electrolyte secondary battery of the fourth embodiment. This is a diagram corresponding to Figure 4 in the non-aqueous electrolyte secondary battery of the fourth embodiment. This is a diagram corresponding to Figure 3 in the non-aqueous electrolyte secondary battery of the fifth embodiment. This is a diagram corresponding to Figure 4 in the non-aqueous electrolyte secondary battery of the fifth embodiment. This is a diagram corresponding to Figure 3 in the non-aqueous electrolyte secondary battery of the sixth embodiment. This is a diagram corresponding to Figure 4 in the non-aqueous electrolyte secondary battery of the sixth embodiment. This is a diagram corresponding to Figure 3 in the non-aqueous electrolyte secondary battery of the seventh embodiment. This is a diagram corresponding to Figure 4 in the seventh embodiment of the non-aqueous electrolyte secondary battery. This is a diagram corresponding to Figure 3 in the eighth embodiment of the non-aqueous electrolyte secondary battery. This is a diagram corresponding to Figure 4 in the eighth embodiment of the non-aqueous electrolyte secondary battery. This is a diagram corresponding to Figure 3 in the ninth embodiment of the non-aqueous electrolyte secondary battery. This is a diagram corresponding to Figure 4 comparative example of the non-aqueous electrolyte secondary battery.

[0009] Hereinafter, an example of an embodiment of a non-aqueous electrolyte secondary battery according to this disclosure will be described in detail with reference to the drawings. The embodiment described below is merely an example, and this disclosure is not limited to the embodiments described below. Furthermore, forms obtained by selectively combining each component of the embodiments described below are included in this disclosure.

[0010] [First Embodiment] The configuration of the non-aqueous electrolyte secondary battery 10, which is the first embodiment, will be described with reference to Figures 1 and 2. Figure 1 is a schematic diagram showing a cross-section of the non-aqueous electrolyte secondary battery 10, and Figure 2 is a perspective view of the electrode body 14 that constitutes the non-aqueous electrolyte secondary battery 10. Note that in Figures 1 and 2, the insulating layer 50, which will be described later, is not shown for clarity.

[0011] As shown in Figures 1 and 2, the non-aqueous electrolyte secondary battery 10 comprises an electrode body 14 in which a first electrode and a second electrode are wound around a separator 13, a non-aqueous electrolyte (not shown), an outer container 15 that houses the electrode body 14 and the non-aqueous electrolyte, and a sealing body 16 that closes the opening of the outer container 15. In this specification, the side of the non-aqueous electrolyte secondary battery 10 with the sealing body 16 is referred to as "upper," and the bottom side of the outer container 15 is referred to as "lower." Furthermore, the following description will focus on the case where the first electrode is the positive electrode 11 and the second electrode is the negative electrode 12.

[0012] The electrode body 14 has a positive electrode 11, a negative electrode 12, and a separator 13, and the positive electrode 11 and the negative electrode 12 are wound in a spiral shape via the separator 13. The positive electrode 11, the negative electrode 12, and the separator 13 that make up the electrode body 14 are all elongated strips, and are alternately stacked in the radial direction of the electrode body 14 by being wound in a spiral shape. The positive electrode 11 protrudes above the negative electrode 12 and the separator 13, and the negative electrode 12 protrudes below the positive electrode 11 and the separator 13. For example, two separators 13 are arranged so as to sandwich the positive electrode 11.

[0013] The positive electrode 11 comprises a positive electrode core 30 and a positive electrode mixture layer 31 formed on the positive electrode core 30. The positive electrode core 30 can be made of a metal foil that is stable within the potential range of the positive electrode 11, such as aluminum or an aluminum alloy, or a film with the metal arranged on its surface. The positive electrode mixture layer 31 contains a positive electrode active material, a conductive agent, and a binder, and is preferably formed on both sides of the positive electrode core 30, excluding the non-mixture layer portion 32 described later. The positive electrode 11 can be manufactured, for example, by applying a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, and a binder onto the positive electrode core 30, drying the coating, and then compressing it to form the positive electrode mixture layer 31 on both sides of the positive electrode core 30.

[0014] The positive electrode composite layer 31 contains particulate lithium metal composite oxide as the positive electrode active material. The lithium metal composite oxide is a composite oxide containing metal elements such as Co, Mn, Ni, and Al in addition to Li. The metal elements constituting the lithium metal composite oxide are, for example, at least one selected from Mg, Al, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Y, Zr, Sn, Sb, W, Pb, and Bi. Among these, it is preferable to contain at least one selected from Co, Ni, and Mn. Examples of suitable composite oxides include lithium metal composite oxides containing Ni, Co, and Mn, or lithium metal composite oxides containing Ni, Co, and Al.

[0015] Examples of conductive agents included in the positive electrode mixture layer 31 include carbon black such as acetylene black and Ketjenblack, graphite, carbon nanotubes (CNTs), carbon nanofibers, and graphene. Examples of binders included in the positive electrode mixture layer 31 include fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyimide, acrylic resins, and polyolefins. In addition, these resins may be used in combination with carboxymethylcellulose (CMC) or its salts, polyethylene oxide (PEO), etc.

[0016] The negative electrode 12 comprises a negative electrode core 40 and a negative electrode mixture layer 41 formed on the negative electrode core 40. The negative electrode core 40 can be made of a metal foil that is stable in the potential range of the negative electrode 12, such as copper or a copper alloy, or a film with the metal arranged on its surface. The negative electrode mixture layer 41 contains a negative electrode active material, a binder, and optionally a conductive agent, and is preferably formed on both sides of the negative electrode core 40, excluding the non-mixture layer portion 42 described later. The negative electrode 12 can be manufactured by applying a negative electrode mixture slurry containing a negative electrode active material and a binder to the surface of the negative electrode core 40, drying the coating, and then compressing it to form the negative electrode mixture layer 41 on both sides of the negative electrode core 40.

[0017] The negative electrode mixture layer 41 generally contains a carbon material that reversibly intercepts and releases lithium ions as the negative electrode active material. A suitable example of the carbon material is graphite such as natural graphite like flake graphite, lump graphite, or clay graphite, or artificial graphite such as lump graphite (MAG) or graphitized mesophase carbon microbeads (MCMB). In addition, a material containing at least one of an element that alloys with Li, such as Si or Sn, and a material containing such an element may be used as the negative electrode active material. Among these, composite materials containing Si are preferred.

[0018] A preferred example of a composite material containing Si is SiO ２ Examples include materials in which Si fine particles are dispersed in a phase or silicate phase such as lithium silicate, or materials in which Si fine particles are dispersed in an amorphous carbon phase. A conductive layer, such as a carbon film, is formed on the particle surface of the composite material. Using a carbon material and a Si-containing composite material in combination as a negative electrode active material is preferable from the viewpoint of achieving both high capacity and high durability of the battery.

[0019] The binder in the negative electrode mixture layer 41 may be a fluororesin, PAN, polyimide, acrylic resin, polyolefin, etc., similar to the positive electrode mixture layer, but styrene-butadiene rubber (SBR) is preferred. Furthermore, the negative electrode mixture layer 41 preferably contains CMC or a salt thereof, polyacrylic acid (PAA) or a salt thereof, polyvinyl alcohol (PVA), etc. Among these, a combination of SBR and CMC or a salt thereof, PAA or a salt thereof is preferred. The negative electrode mixture layer 41 may also contain a conductive agent such as CNT.

[0020] The non-aqueous electrolyte secondary battery 10 has a metal positive electrode current collector plate 17 on the upper side of the electrode body 14. The positive electrode current collector plate 17 is made of, for example, aluminum or an aluminum alloy. As will be described in detail later, the non-composite portion 32 of the positive electrode 11 is connected to the lower surface of the positive electrode current collector plate 17. The shape of the positive electrode current collector plate 17 is not particularly limited; for example, it may have a disc or annular shape, or it may have a roughly cross shape. A positive electrode lead 20 is connected to the upper surface of the positive electrode current collector plate 17. The positive electrode lead 20 extends towards the sealing body 16 through a through hole in the insulating plate 19, and the upper end of the positive electrode lead 20 is connected to the lower surface of the filter 22 of the sealing body 16 by welding or the like. Thus, the cap 26 that constitutes the top plate of the sealing body 16 is electrically connected to the filter 22, and the cap 26 becomes the positive electrode terminal.

[0021] The non-aqueous electrolyte secondary battery 10 has a metal negative electrode current collector plate 18 on the lower side of the electrode body 14. As will be described in more detail later, the non-compound layer-formed portion 42 of the negative electrode 12 is connected to the upper surface of the negative electrode current collector plate 18. The negative electrode current collector plate 18 is also bonded to the inner surface of the bottom plate of the outer casing 15. Therefore, the outer casing 15, which is electrically connected to the negative electrode 12 via the negative electrode current collector plate 18, becomes the negative electrode terminal.

[0022] As shown in Figures 1 and 2, the positive electrode 11 has a non-compound layer portion 32 at the upper axial end of the electrode body 14 where the positive electrode compound layer 31 is not provided. The non-compound layer portion 32 is provided over the range from the beginning end to the end end of the winding in the longitudinal direction of the elongated positive electrode 11. The non-compound layer portion 32 is bent radially inward and welded to the positive electrode current collector plate 17 at its upper end. By joining the non-compound layer portion 32 to the positive electrode current collector plate 17, the contact area between the non-compound layer portion 32 and the positive electrode current collector plate 17 is increased, so the internal resistance of the positive electrode 11 can be reduced compared to when the positive electrode 11 and the positive electrode current collector plate 17 are connected by a positive electrode tab or the like.

[0023] Furthermore, as shown in Figures 1 and 2, the negative electrode 12 has a non-compound layer portion 42 at the lower axial end of the electrode body 14 where the negative electrode compound layer 41 is not provided. The non-compound layer portion 42 is provided over the range from the beginning end to the end end of the winding in the longitudinal direction of the elongated negative electrode 12, similar to the case of the positive electrode 11. The non-compound layer portion 42 is bent radially inward at its lower end and welded to the negative electrode current collector plate 18. Note that the non-aqueous electrolyte secondary battery 10 may not have a negative electrode current collector plate 18, and the non-compound layer portion 42 may be joined to the inner surface of the bottom plate of the outer casing 15.

[0024] A porous sheet having ion permeability and insulating properties is used for the separator 13. Specific examples of porous sheets include microporous thin films, woven fabrics, and nonwoven fabrics. Suitable materials for the separator 13 include polyethylene, polyolefins such as polypropylene, and cellulose. The separator 13 may have a single-layer structure or a multi-layer structure. A heat-resistant resin layer, such as aramid resin, may be formed on the surface of the separator 13. A filler layer containing an inorganic filler may be formed at the interface between the separator 13 and at least one of the positive electrode 11 and the negative electrode 12.

[0025] Non-aqueous electrolytes are lithium-ion conductive. A non-aqueous electrolyte comprises 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. Non-aqueous solvents may also contain halogen-substituted compounds (e.g., fluoroethylene carbonate) in which at least some of the hydrogen atoms in these solvents are replaced with halogen atoms such as fluorine. Examples of electrolyte salts include LiPF4. ６ Lithium salts such as these are used.

[0026] The outer container 15 is a bottomed cylindrical metal container with one end open in the axial direction, and the opening of the outer container 15 is sealed by a sealing body 16.

[0027] A gasket 27 is provided between the outer casing 15 and the sealing body 16 to ensure airtightness inside the battery. The outer casing 15 has a grooved portion 21 formed on its side surface, which protrudes inward to support the sealing body 16. The grooved portion 21 is preferably formed in an annular shape along the circumferential direction of the outer casing 15, and its upper surface supports the sealing body 16. The sealing body 16 is fixed to the upper part of the outer casing 15 by the grooved portion 21 and the open end of the outer casing 15 which is crimped to the sealing body 16.

[0028] The sealing body 16 has a structure in which a filter 22, a lower valve body 23, an insulating member 24, an upper valve body 25, and a cap 26 are stacked in order from the electrode body 14 side. Each component constituting the sealing body 16 has, for example, a disc shape or a ring shape, and each component except the insulating member 24 is electrically connected to one another. The filter 22 has at least one through hole. The lower valve body 23 and the upper valve body 25 are connected at their respective centers, and the insulating member 24 is interposed between their respective peripheral edges.

[0029] When the non-aqueous electrolyte secondary battery 10 overheats abnormally and its internal pressure rises, the lower valve body 23 deforms and ruptures, pushing the upper valve body 25 towards the cap 26, thereby interrupting the current path between the lower valve body 23 and the upper valve body 25. If the internal pressure rises further, the upper valve body 25 ruptures, and gas is released from the through-hole 26a of the cap 26. This release of gas prevents the non-aqueous electrolyte secondary battery 10 from rupturing due to an excessive rise in internal pressure, thus improving the safety of the non-aqueous electrolyte secondary battery 10. The configuration of the sealing body 16 is not limited to this.

[0030] Next, the configuration of the upper end of the positive electrode 11 will be described in detail with reference to Figures 3 and 4. Figure 3 is an enlarged view of the upper part of the electrode body 14 in Figure 1, and Figure 4 is a plan view showing the positive electrode 11 in an unfolded state.

[0031] As shown in Figures 3 and 4, the positive electrode 11 has a positive electrode core 30 and a positive electrode mixture layer 31 disposed on the positive electrode core 30. The upper end of the positive electrode 11 is provided with a non-composite mixture layer portion 32 where the positive electrode mixture layer 31 is not disposed on the positive electrode core 30. The non-composite mixture layer portion 32 has a substantially uniform width over the range from the winding start end 11X to the winding end end 11Y in the longitudinal direction of the positive electrode 11. The width of the non-composite mixture layer portion 32 is, for example, 3 mm or more and 25 mm or less, and may be 5 mm or more and 20 mm or less.

[0032] In the lower region of the non-compound layer formation portion 32, an insulating layer formation portion 33 is provided on at least one surface of the positive electrode core 30 where an insulating layer 50 is formed. In this embodiment, the insulating layer 50 is provided on both sides of the positive electrode core 30. By providing the insulating layer 50, contact between the positive electrode core 30 and the opposing negative electrode 12 is suppressed. As a result, the occurrence of internal short circuits and the like is suppressed, and the reliability of the non-aqueous electrolyte secondary battery 10 is improved.

[0033] The insulating layer 50 includes, for example, an inorganic material and a resin material (binder). The insulating layer 50 is formed, for example, by applying an insulating layer slurry containing an inorganic material and a resin material (binder) to the surface of the positive electrode core 30 and drying the coating film.

[0034] Examples of inorganic materials include metal oxides, metal nitrides, metal fluorides, and carbides. Examples of metal oxides include aluminum oxide, titanium oxide, magnesium oxide, zirconium oxide, nickel oxide, and manganese oxide. Examples of metal nitrides include titanium nitride, boron nitride, aluminum nitride, magnesium nitride, and silicon nitride. Examples of metal fluorides include aluminum fluoride, lithium fluoride, sodium fluoride, magnesium fluoride, calcium fluoride, and barium fluoride. Examples of carbides include silicon carbide, boron carbide, titanium carbide, and tungsten carbide. In addition, inorganic materials include zeolites (M ２／ｎ O. Al ２ O ３ xSiO ２ ・yH ２O and M are metal elements, n is the valence of M, x ≥ 2, y ≥ 0), etc., porous aluminosilicates, talc (Mg ３ Si ４ O １０ (OH) ２ ) etc., layered silicates, barium titanate (BaTiO ３ ), strontium titanate (SrTiO ３ ) etc., minerals may also be used. These may be used alone or in combination of two or more.

[0035] The inorganic material is, for example, composed of particulate inorganic particles. The average particle diameter of the inorganic particles is, for example, 0.05 μm or more and 2 μm or less. The average particle diameter of the inorganic particles means the particle diameter at which the cumulative frequency in the volume-based particle size distribution becomes 50% from the smaller particle diameter side, and is also called the median diameter. The particle size distribution of the inorganic particles can be measured using a laser diffraction type particle size distribution measuring device (for example, manufactured by Microtrac Bell Co., Ltd., MT3000II) with water as the dispersion medium.

[0036] The content rate of the inorganic material in the insulating layer 50 is, for example, 60% by mass or more and 99% by mass or less, preferably 70% by mass or more and 95% by mass or less, based on the total mass of the insulating layer 50. When the content rate of the inorganic material is within the above range, it becomes easier to form the insulating layer 50 on the surface of the positive electrode core 30.

[0037] The resin material contained in the insulating layer 50 is preferably a polymer material, for example, fluorine-based resins such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), polyimide-based resins, polyamide-based resins, acrylic resins, polyolefin-based resins, styrene-butadiene rubber (SBR), nitrile-butadiene rubber (NBR), carboxymethyl cellulose (CMC) or its salts, polyacrylic acid (PAA) or its salts, polyvinyl alcohol (PVA), etc. can be exemplified. These may be used alone or in combination of two or more.

[0038] The thickness of the insulating layer 50 is smaller than the one-sided thickness of the positive electrode mixture layer 31, for example, 10 μm or more and 50 μm or less. When the thickness of the insulating layer 50 is within the above range, internal short circuit can be more suppressed while ensuring productivity.

[0039] In the non-formation part 32 of the mixture layer, a core exposed part 34 where the positive electrode core 30 is exposed is provided in the region above the insulating layer formation part 33. And the non-formation part 32 of the mixture layer is bent radially inward starting from the boundary part between the insulating layer formation part 33 and the core exposed part 34, and the core exposed part 34 is welded to the positive electrode current collector plate 17.

[0040] Here, the width of the insulating layer formation part 33 is different in the longitudinal direction of the positive electrode 11. In the present embodiment, the width of the insulating layer formation part 33 continuously increases from the start end 11X of winding of the positive electrode 11 to the end 11Y of winding. Thereby, as going to the start side of winding of the positive electrode 11, the bending part of the non-formation part 32 of the mixture layer is formed on the lower side, and the inclination angle of the core exposed part 34 with respect to the axial direction of the electrode body 14 becomes small. As a result, when injecting the non-aqueous electrolyte, the non-aqueous electrolyte easily enters the radially inner side of the electrode body 14, and the injection time of the non-aqueous electrolyte can be shortened. Also, even during charge and discharge, the diffusibility of the non-aqueous electrolyte in the radially inner side of the electrode body 14 is improved. As a result, the reaction unevenness of the charge and discharge reaction inside the electrode body 14 is suppressed, and the cycle characteristics are improved.

[0041] In the present embodiment, at the start end 11X of winding of the positive electrode 11, the width of the insulating layer formation part 33 is minimum, and at the end 11Y of winding of the positive electrode 11, the width of the insulating layer formation part 33 is maximum. It is preferable that the maximum value of the width of the insulating layer formation part 33 is 1.5 times or more and 10 times or less of the minimum value of the width of the insulating layer formation part 33, and more preferably 2 times or more and 8 times or less. By setting the maximum value of the width of the insulating layer formation part 33 to be 1.5 times or more and 10 times or less of the minimum value of the width of the insulating layer formation part 33, the injectability and diffusibility of the non-aqueous electrolyte can be further improved while suppressing internal short circuit.

[0042] The maximum width of the insulating layer-forming portion 33 is, for example, 40% to 80% of the width of the non-forming portion 32 of the composite layer. In this case, the pourability and diffusivity of the non-aqueous electrolyte can be further improved. The minimum width of the insulating layer-forming portion 33 is, for example, 5% to 40% of the width of the non-forming portion 32 of the composite layer. In this case, the occurrence of internal short circuits at the point where the width of the insulating layer-forming portion 33 is minimized can be further suppressed.

[0043] [Second Embodiment] Next, a second embodiment of the non-aqueous electrolyte secondary battery 10 will be described with reference to Figures 5 and 6. Figure 5 is a diagram corresponding to Figure 3 in the second embodiment, and Figure 6 is a diagram corresponding to Figure 4 in the second embodiment. In the following, the same reference numerals will be used for components common to the first embodiment, and redundant explanations will be omitted. The differences from the first embodiment will be explained in detail.

[0044] As shown in Figures 5 and 6, the arrangement of the insulating layer 50 (insulating layer forming portion 33) in the positive electrode 11 of the second embodiment differs from that of the positive electrode 11 of the first embodiment. Specifically, in this embodiment, the width of the insulating layer forming portion 33 decreases continuously from the winding start end 11X to the winding end end 11Y of the positive electrode 11. That is, the width of the insulating layer forming portion 33 is maximum at the winding start end 11X of the positive electrode 11, and minimum at the winding end end 11Y of the positive electrode 11.

[0045] As a result, the bent portion of the non-compound layer-forming portion 32 is formed on the lower side as it approaches the end of the winding of the positive electrode 11, and the inclination angle of the core body exposed portion 34 with respect to the axial direction of the electrode body 14 decreases. Consequently, when injecting the non-aqueous electrolyte, the non-aqueous electrolyte can more easily penetrate to the radially outer side of the electrode body 14, shortening the injection time of the non-aqueous electrolyte. Furthermore, during charging and discharging, the diffusivity of the non-aqueous electrolyte on the radially outer side of the electrode body 14 is improved. As a result, reaction unevenness in the charge-discharge reaction inside the electrode body 14 is suppressed, and the cycle characteristics are improved.

[0046] [Third Embodiment] Next, a third embodiment of the non-aqueous electrolyte secondary battery 10 will be described with reference to Figures 7 and 8. Figure 7 is a diagram corresponding to Figure 3 in the third embodiment, and Figure 8 is a diagram corresponding to Figure 4 in the third embodiment. In the following, the same reference numerals will be used for components common to the first embodiment, and redundant explanations will be omitted. The differences from the first embodiment will be explained in detail.

[0047] As shown in Figures 7 and 8, the arrangement of the insulating layer 50 (insulating layer forming portion 33) in the positive electrode 11 of the third embodiment differs from that of the positive electrode 11 of the first embodiment. Specifically, in this embodiment, the positive electrode 11 has a change point 35 in the middle of its longitudinal direction. The width of the insulating layer forming portion 33 continuously decreases from the winding start end 11X of the positive electrode 11 to the change point 35, and increases at the change point 35, and the width of the insulating layer forming portion 33 continuously decreases from the change point 35 to the winding end end 11Y. In other words, the insulating layer forming portion 33 of this embodiment has a first region 33A and a second region 33B on the winding start side and winding end side of the change point 35, respectively, where the width of the insulating layer forming portion 33 continuously decreases toward the winding end side.

[0048] In the examples shown in Figures 7 and 8, the maximum width of the insulating layer forming portion 33 in the first region 33A and the second region 33B is approximately the same. Similarly, the minimum width of the insulating layer forming portion 33 in the first region 33A and the second region 33B is approximately the same. However, the maximum or minimum width of the insulating layer forming portion 33 in the first region 33A and the second region 33B may be different.

[0049] According to the positive electrode 11 of the third embodiment, as you move from the winding start end 11X of the positive electrode 11 towards the change point 35, the bent portion of the non-compound layer 32 is formed on the lower side, and the inclination angle of the core exposed portion 34 with respect to the axial direction of the electrode body 14 decreases. Also, as you move from the change point 35 of the positive electrode 11 towards the winding end end 11Y, the bent portion of the non-compound layer 32 is formed on the lower side, and the inclination angle of the core exposed portion 34 with respect to the axial direction of the electrode body 14 decreases. As a result, when injecting the non-aqueous electrolyte, the non-aqueous electrolyte can easily enter the radial center and radial outer portion of the electrode body 14, and the injection time of the non-aqueous electrolyte can be shortened. Furthermore, during charging and discharging, the diffusivity of the non-aqueous electrolyte in the radial center and radial outer portion of the electrode body 14 is improved. As a result, reaction unevenness in the charge-discharge reaction inside the electrode body 14 is suppressed, and the cycle characteristics are improved.

[0050] The position of the change point 35 is, for example, 0.3L to 0.7L away from the winding start end 11X of the positive electrode 11, where L is the longitudinal length of the positive electrode 11. In this case, the improvement in the pourability and diffusivity of the non-aqueous electrolyte is more pronounced.

[0051] [Fourth Embodiment] Next, a fourth embodiment of the non-aqueous electrolyte secondary battery 10 will be described with reference to Figures 9 and 10. Figure 9 corresponds to Figure 3 in the fourth embodiment, and Figure 10 corresponds to Figure 4 in the fourth embodiment. In the following, components common to the first embodiment will be referred to with the same reference numerals, and redundant explanations will be omitted. The differences from the first embodiment will be explained in detail.

[0052] As shown in Figures 9 and 10, the arrangement of the insulating layer 50 (insulating layer forming portion 33) in the positive electrode 11 of the fourth embodiment differs from that of the positive electrode 11 of the first embodiment. Specifically, in this embodiment, the positive electrode 11 has a change point 35 in the middle of its longitudinal direction. The width of the insulating layer forming portion 33 continuously increases from the winding start end 11X of the positive electrode 11 to the change point 35, and decreases at the change point 35, while the width of the insulating layer forming portion 33 continuously increases from the change point 35 to the winding end end 11Y. In other words, the insulating layer forming portion 33 of this embodiment has a first region 33A and a second region 33B on the winding start side and winding end side of the change point 35, respectively, where the width of the insulating layer forming portion 33 continuously increases toward the winding end side.

[0053] In the examples shown in Figures 9 and 10, the maximum width of the insulating layer forming portion 33 in the first region 33A and the second region 33B is approximately the same. Similarly, the minimum width of the insulating layer forming portion 33 in the first region 33A and the second region 33B is approximately the same. However, the maximum or minimum width of the insulating layer forming portion 33 in the first region 33A and the second region 33B may be different.

[0054] According to the positive electrode 11 of the fourth embodiment, as you move from the change point 35 of the positive electrode 11 towards the winding start side, the bent portion of the non-compound layer-forming portion 32 is formed on the lower side, and the inclination angle of the core-exposed portion 34 with respect to the axial direction of the electrode body 14 decreases. Also, as you move from the winding end end 11Y of the positive electrode 11 towards the change point 35 side, the bent portion of the non-compound layer-forming portion 32 is formed on the lower side, and the inclination angle of the core-exposed portion 34 with respect to the axial direction of the electrode body 14 decreases. As a result, when injecting the non-aqueous electrolyte, the non-aqueous electrolyte can easily enter the radial center and radially inward portion of the electrode body 14, and the injection time of the non-aqueous electrolyte can be shortened. Furthermore, during charging and discharging, the diffusivity of the non-aqueous electrolyte in the radial center and radially inward portion of the electrode body 14 is improved. As a result, reaction unevenness in the charge-discharge reaction inside the electrode body 14 is suppressed, and the cycle characteristics are improved.

[0055] The position of the change point 35 is, for example, 0.3L to 0.7L away from the winding start end 11X of the positive electrode 11, where L is the longitudinal length of the positive electrode 11. In this case, the improvement in the pourability and diffusivity of the non-aqueous electrolyte is more pronounced.

[0056] [Fifth Embodiment] Next, the non-aqueous electrolyte secondary battery 10, which is the fifth embodiment, will be described with reference to Figures 11 and 12. Figure 11 is a diagram corresponding to Figure 3 in the fifth embodiment, and Figure 12 is a diagram corresponding to Figure 4 in the fifth embodiment. In the following, the same reference numerals will be used for components common to the first embodiment, and redundant explanations will be omitted. The differences from the first embodiment will be explained in detail.

[0057] As shown in Figures 11 and 12, the arrangement of the insulating layer 50 (insulating layer forming portion 33) in the positive electrode 11 of the fifth embodiment differs from that of the positive electrode 11 of the first embodiment. Specifically, in this embodiment, the positive electrode 11 has a change point 35 in the middle of its longitudinal direction. The width of the insulating layer forming portion 33 continuously decreases from the winding start end 11X to the change point 35, and the width of the insulating layer forming portion 33 continuously increases from the winding end end 11Y to the winding end end 11Y. In other words, the insulating layer forming portion 33 of this embodiment has a first region 33A on the winding start side of the change point 35 where the width of the insulating layer forming portion 33 continuously increases toward the winding start side, and a second region 33B on the winding end side of the change point 35 where the width of the insulating layer forming portion 33 continuously increases toward the winding end side.

[0058] In the examples shown in Figures 11 and 12, the maximum width of the insulating layer forming portion 33 in the first region 33A and the second region 33B is approximately the same. Similarly, the minimum width of the insulating layer forming portion 33 in the first region 33A and the second region 33B is approximately the same. However, the maximum or minimum width of the insulating layer forming portion 33 in the first region 33A and the second region 33B may be different.

[0059] According to the positive electrode 11 of the fifth embodiment, as you move from the winding start end 11X of the positive electrode 11 towards the change point 35, the bent portion of the non-compound layer-forming portion 32 is formed on the lower side, and the inclination angle of the core-exposed portion 34 with respect to the axial direction of the electrode body 14 decreases. Similarly, as you move from the winding end 11Y of the positive electrode 11 towards the change point 35, the bent portion of the non-compound layer-forming portion 32 is formed on the lower side, and the inclination angle of the core-exposed portion 34 with respect to the axial direction of the electrode body 14 decreases. As a result, when injecting the non-aqueous electrolyte, the non-aqueous electrolyte can penetrate more easily into the radial center of the electrode body 14, and the injection time of the non-aqueous electrolyte can be shortened. Furthermore, during charging and discharging, the diffusivity of the non-aqueous electrolyte in the radial center of the electrode body 14 is further improved. As a result, unevenness in the charge-discharge reaction inside the electrode body 14 is suppressed, and the cycle characteristics are improved.

[0060] The position of the change point 35 is, for example, 0.3L to 0.7L away from the winding start end 11X of the positive electrode 11, where L is the longitudinal length of the positive electrode 11. In this case, the improvement in the pourability and diffusivity of the non-aqueous electrolyte is more pronounced.

[0061] [Sixth Embodiment] Next, the sixth embodiment of the non-aqueous electrolyte secondary battery 10 will be described with reference to Figures 13 and 14. Figure 13 is a diagram corresponding to Figure 3 in the sixth embodiment, and Figure 14 is a diagram corresponding to Figure 4 in the sixth embodiment. In the following, the same reference numerals will be used for components common to the first embodiment, and redundant explanations will be omitted. The differences from the first embodiment will be explained in detail.

[0062] As shown in Figures 13 and 14, the arrangement of the insulating layer 50 (insulating layer forming portion 33) in the positive electrode 11 of the sixth embodiment differs from that of the positive electrode 11 of the first embodiment. Specifically, in this embodiment, the positive electrode 11 has a change point 35 in the middle of its longitudinal direction. The width of the insulating layer forming portion 33 continuously increases from the winding start end 11X to the change point 35, and the width of the insulating layer forming portion 33 continuously decreases from the winding end end 11Y to the winding end end 11Y. In other words, the insulating layer forming portion 33 of this embodiment has a first region 33A on the winding start side of the change point 35 where the width of the insulating layer forming portion 33 continuously decreases toward the winding start side, and a second region 33B on the winding end side of the change point 35 where the width of the insulating layer forming portion 33 continuously decreases toward the winding end side.

[0063] In the examples shown in Figures 13 and 14, the maximum width of the insulating layer forming portion 33 in the first region 33A and the second region 33B is approximately the same. Similarly, the minimum width of the insulating layer forming portion 33 in the first region 33A and the second region 33B is approximately the same. However, the maximum or minimum width of the insulating layer forming portion 33 in the first region 33A and the second region 33B may be different.

[0064] According to the positive electrode 11 of the sixth embodiment, as you move from the change point 35 of the positive electrode 11 towards the winding start side, the bent portion of the non-compound layer formation portion 32 is formed on the lower side, and the inclination angle of the core body exposed portion 34 with respect to the axial direction of the electrode body 14 decreases. Also, as you move from the change point 35 of the positive electrode 11 towards the winding end side, the bent portion of the non-compound layer formation portion 32 is formed on the lower side, and the inclination angle of the core body exposed portion 34 with respect to the axial direction of the electrode body 14 decreases. As a result, when injecting the non-aqueous electrolyte, the non-aqueous electrolyte can penetrate more easily into the radially inner and radially outer sides of the electrode body 14, and the injection time of the non-aqueous electrolyte can be shortened. Furthermore, during charging and discharging, the diffusivity of the non-aqueous electrolyte on the radially inner and radially outer sides of the electrode body 14 is further improved. As a result, reaction unevenness in the charge-discharge reaction inside the electrode body 14 is suppressed, and the cycle characteristics are improved.

[0065] The position of the change point 35 is, for example, 0.3L to 0.7L away from the winding start end 11X of the positive electrode 11, where L is the longitudinal length of the positive electrode 11. In this case, the improvement in the pourability and diffusivity of the non-aqueous electrolyte is more pronounced.

[0066] [Seventh Embodiment] Next, the seventh embodiment of the non-aqueous electrolyte secondary battery 10 will be described with reference to Figures 15 and 16. Figure 15 corresponds to Figure 3 in the seventh embodiment, and Figure 16 corresponds to Figure 4 in the seventh embodiment. In the following, components common to the first embodiment will be given the same reference numerals, and redundant explanations will be omitted. The differences from the first embodiment will be explained in detail.

[0067] As shown in Figures 15 and 16, the arrangement of the insulating layer 50 (insulating layer forming portion 33) in the positive electrode 11 of the seventh embodiment differs from that of the positive electrode 11 of the first embodiment. Specifically, in this embodiment, the positive electrode 11 has three transition points 35A, 35B, and 35C in the longitudinal middle portion. The width of the insulating layer forming portion 33 continuously decreases from the winding start end 11X of the positive electrode 11 to transition point 35A, and the width of the insulating layer forming portion 33 continuously increases from transition point 35A to transition point 35B. Furthermore, the width of the insulating layer forming portion 33 continuously decreases from transition point 35B to transition point 35C, and the width of the insulating layer forming portion 33 continuously increases from transition point 35C to the winding end end 11Y of the positive electrode 11. In other words, the width of the insulating layer forming portion 33 is maximum at the winding end 11X, winding end 11Y, and transition point 35B of the positive electrode 11, and minimum at transition points 35A and 35C. Note that the widths of the insulating layer forming portion 33 at the winding end 11X, winding end 11Y, and transition point 35B of the positive electrode 11 may be different. Also, the widths of the insulating layer forming portion 33 at transition points 35A and 35C may be different.

[0068] According to the positive electrode 11 of the seventh embodiment, as you move from the winding start end 11X and the transition point 35B toward the transition point 35A of the positive electrode 11, the bent portion of the non-compound layer-forming portion 32 is formed on the lower side, and the inclination angle of the core-exposed portion 34 with respect to the axial direction of the electrode body 14 decreases. Also, as you move from the winding end end 11Y and the transition point 35B toward the transition point 35C of the positive electrode 11, the bent portion of the non-compound layer-forming portion 32 is formed on the lower side, and the inclination angle of the core-exposed portion 34 with respect to the axial direction of the electrode body 14 decreases. As a result, when injecting the non-aqueous electrolyte, the non-aqueous electrolyte can penetrate more easily into the radial center of the electrode body 14 (near the transition points 35A and 35C), and the injection time of the non-aqueous electrolyte can be shortened. Furthermore, during charging and discharging, the diffusivity of the non-aqueous electrolyte is further improved in the radially inner and radially central portions (near the transition points 35A and 35C) of the electrode body 14. As a result, unevenness in the charge-discharge reaction within the electrode body 14 is suppressed, and the cycle characteristics are improved.

[0069] The position of change point 35A is, for example, 0.1L to 0.4L away from the winding start end 11X of the positive electrode 11, where L is the longitudinal length of the positive electrode 11. The position of change point 35B is, for example, 0.3L to 0.7L away from the winding start end 11X of the positive electrode 11. The position of change point 35C is, for example, 0.6L to 0.9L away from the winding start end 11X of the positive electrode 11. When the positions of change points 35A, 35B, and 35C are within the above ranges, the improvement in the pourability and diffusivity of the non-aqueous electrolyte is more pronounced.

[0070] [Eighth Embodiment] Next, the eighth embodiment of the non-aqueous electrolyte secondary battery 10 will be described with reference to Figures 17 and 18. Figure 17 is a diagram corresponding to Figure 3 in the eighth embodiment, and Figure 18 is a diagram corresponding to Figure 4 in the eighth embodiment. In the following, the same reference numerals will be used for components common to the first embodiment, and redundant explanations will be omitted. The differences from the first embodiment will be explained in detail.

[0071] As shown in Figures 17 and 18, the arrangement of the insulating layer 50 (insulating layer forming portion 33) in the positive electrode 11 of the eighth embodiment differs from that of the positive electrode 11 of the first embodiment. Specifically, in this embodiment, the positive electrode 11 has four transition points 35A, 35B, 35C, and 35D in the longitudinal middle portion. The width of the insulating layer forming portion 33 continuously decreases from the winding start end 11X of the positive electrode 11 to transition point 35A, and continuously increases from transition point 35A to transition point 35B. Furthermore, the width of the insulating layer forming portion 33 continuously decreases from transition point 35B to transition point 35C, and continuously increases from transition point 35C to transition point 35D. Finally, the width of the insulating layer forming portion 33 continuously decreases from transition point 35D to the winding end end 11Y of the positive electrode 11. In other words, the width of the insulating layer forming portion 33 is maximum at the winding start end 11X of the positive electrode 11, at the change point 35B, and at the change point 35D, and minimum at the change points 35A, 35C, and at the winding end end 11Y of the positive electrode 11. Note that the widths of the insulating layer forming portion 33 at the winding start end 11X of the positive electrode 11, at the change point 35B, and at the change point 35D may be different. Also, the widths of the insulating layer forming portion 33 at the change points 35A, 35C, and at the winding end end 11Y of the positive electrode 11 may be different.

[0072] According to the positive electrode 11 of the eighth embodiment, as you move from the winding start end 11X and change point 35B toward change point 35A, the bent portion of the non-formed compound layer 32 is formed on the lower side, and the inclination angle of the exposed core portion 34 with respect to the axial direction of the electrode body 14 decreases. Also, as you move from change points 35B and 35D toward change point 35C, the bent portion of the non-formed compound layer 32 is formed on the lower side, and the inclination angle of the exposed core portion 34 with respect to the axial direction of the electrode body 14 decreases. Also, as you move from change point 35D toward the winding end end 11Y of the positive electrode 11, the bent portion of the non-formed compound layer 32 is formed on the lower side, and the inclination angle of the exposed core portion 34 with respect to the axial direction of the electrode body 14 decreases. As a result, when injecting the non-aqueous electrolyte, the non-aqueous electrolyte can more easily penetrate the radial center (near the change points 35A and 35C) and the radial outer part of the electrode body 14, thereby shortening the injection time of the non-aqueous electrolyte. Furthermore, during charging and discharging, the diffusivity of the non-aqueous electrolyte is further improved in the radial inner part, the radial center (near the change points 35A and 35C), and the radial outer part of the electrode body 14. As a result, reaction unevenness in the charge-discharge reaction inside the electrode body 14 is suppressed, and the cycle characteristics are improved.

[0073] The position of change point 35A is, for example, 0.05L to 0.3L away from the winding start end 11X of the positive electrode 11, where L is the longitudinal length of the positive electrode 11. The position of change point 35B is, for example, 0.2L to 0.5L away from the winding start end 11X of the positive electrode 11. The position of change point 35C is, for example, 0.5L to 0.8L away from the winding start end 11X of the positive electrode 11. The position of change point 35D is, for example, 0.7L to 0.95L away from the winding start end 11X of the positive electrode 11. When the positions of change points 35A, 35B, 35C, and 35D are within the above ranges, the improvement in the pourability and diffusivity of the non-aqueous electrolyte is more pronounced.

[0074] Furthermore, in the eighth embodiment, the width of the insulating layer forming portion 33 changes gradually in the vicinity of each change point 35A, 35B, 35C, and 35D. As a result, in the vicinity of each change point 35A, 35B, 35C, and 35D, the non-forming portion 32 of the composite layer is more easily bent radially starting from the boundary between the insulating layer forming portion 33 and the core body exposed portion 34.

[0075] [Ninth Embodiment] Next, the ninth embodiment of the non-aqueous electrolyte secondary battery 10 will be described with reference to Figures 19 and 20. Figure 19 corresponds to Figure 3 in the ninth embodiment, and Figure 20 corresponds to Figure 4 in the ninth embodiment. In the following, components common to the first embodiment will be given the same reference numerals and redundant explanations will be omitted, and the differences from the first embodiment will be explained in detail.

[0076] As shown in Figures 19 and 20, the arrangement of the insulating layer 50 (insulating layer forming portion 33) in the positive electrode 11 of the ninth embodiment differs from that of the positive electrode 11 of the first embodiment. Specifically, in this embodiment, the positive electrode 11 has a change point 35 in the middle of its longitudinal direction. The width of the insulating layer forming portion 33 in the region closer to the start of winding than the change point 35 (first region 33A) is smaller than the width of the insulating layer forming portion 33 in the region closer to the end of winding than the change point 35 (second region 33B). The widths of the insulating layer forming portion 33 in the first region 33A and the second region 33B are substantially constant along the longitudinal direction of the positive electrode 11.

[0077] As a result, the bending portion of the non-composite compound layer 32 is formed lower on the winding start side of the positive electrode 11 compared to the winding end side, and the inclination angle of the core body exposed portion 34 with respect to the axial direction of the electrode body 14 becomes smaller. Consequently, when injecting the non-aqueous electrolyte, the non-aqueous electrolyte can more easily penetrate radially into the electrode body 14, shortening the injection time of the non-aqueous electrolyte. Furthermore, during charging and discharging, the diffusivity of the non-aqueous electrolyte radially into the electrode body 14 is improved. As a result, unevenness in the charge-discharge reaction inside the electrode body 14 is suppressed, and the cycle characteristics are improved.

[0078] Furthermore, the width of the insulating layer forming portion 33 in the region closer to the start of winding than the change point 35 (first region 33A) may be greater than the width of the insulating layer forming portion 33 in the region closer to the end of winding than the change point 35 (second region 33B). In this case, when injecting the non-aqueous electrolyte, the non-aqueous electrolyte can more easily penetrate to the radially outer side of the electrode body 14, thereby shortening the injection time of the non-aqueous electrolyte. In addition, the diffusivity of the non-aqueous electrolyte on the radially outer side of the electrode body 14 is improved during charging and discharging. As a result, unevenness in the charge-discharge reaction inside the electrode body 14 is suppressed, and the cycle characteristics are improved.

[0079] Furthermore, in the example shown in Figure 20, the width of the insulating layer forming portion 33 changes in a stepwise manner near the change point 35, but this is not limited to this. For example, the width of the insulating layer forming portion 33 near the change point 35 may change continuously in the longitudinal direction of the positive electrode 11.

[0080] As described above, the width of the insulating layer forming portion 33 of the positive electrode 11 in this disclosure is formed to differ in the longitudinal direction of the positive electrode 11. This creates injection and diffusion paths for the non-aqueous electrolyte, improving the injection and diffusion properties of the non-aqueous electrolyte. As a result, a non-aqueous electrolyte secondary battery 10 with improved productivity and improved cycle characteristics can be realized.

[0081] The first to ninth embodiments described above can be modified as appropriate within the scope of the purpose of this disclosure. For example, in the first to ninth embodiments described above, the insulating layer 50 is formed on both sides of the non-composite layer portion 32, but it may be formed on only one side. However, from the viewpoint of suppressing the occurrence of internal short circuits, it is preferable that the insulating layer 50 is formed on both sides of the non-composite layer portion 32.

[0082] Furthermore, in the first to eighth embodiments described above, the width of the insulating layer forming portion 33 is continuously increasing or decreasing, but there may be regions where the width of the insulating layer forming portion 33 is substantially constant along the longitudinal direction of the positive electrode 11. For example, in the regions near the winding end 11X and winding end 11Y of the positive electrode 11, the width of the insulating layer forming portion 33 may be substantially constant.

[0083] Furthermore, in the first to ninth embodiments described above, the first electrode is the positive electrode 11 and the second electrode is the negative electrode 12, but the first electrode may be the negative electrode 12 and the second electrode may be the positive electrode 11. In that case, an insulating layer 50 is formed on a part of the non-formed portion 42 of the negative electrode 12.

[0084] The present disclosure will be further illustrated by the following examples, but the present disclosure is not limited to these examples.

[0085] <Example 1> [Preparation of the positive electrode] A lithium transition metal oxide containing Ni, Co, and Mn was used as the positive electrode active material. The above positive electrode active material, acetylene black, and polyvinylidene fluoride were mixed in a solid content mass ratio of 98:1:1, and a positive electrode mixture slurry was prepared using N-methylpyrrolidone (NMP) as the dispersion medium. The slurry was applied to both sides of a long aluminum foil positive electrode core with a thickness of 15 μm, and the coating film was dried and compressed to obtain a positive electrode in which a positive electrode mixture layer was formed on both sides of the positive electrode core. At this time, a 6 mm wide non-composite portion was provided at one end in the width direction of the positive electrode, in which the positive electrode mixture layer was not formed.

[0086] Alumina (Al) as an inorganic material with an average uniform particle size of 0.7 μm ２ O ３ The particles and polyvinylidene fluoride (PVDF) as a binder were mixed in a solid content mass ratio of 90:10, and then an appropriate amount of NMP was added to make a slurry for the insulating layer so that the solid content concentration was 30% by mass. The slurry for the insulating layer was then applied to a portion of both sides of the area where the composite layer was not formed, and the coating was dried to form the insulating layer. At this time, the insulating layer was formed so that the arrangement of the insulating layer formation area was as shown in Figure 4. The maximum width of the insulating layer formation area was set to 3 mm, and the minimum width of the insulating layer formation area was set to 1 mm.

[0087] [Fabrication of the negative electrode] A mixture of graphite and Si oxide (SiO) in a mass ratio of 95:5 was used as the negative electrode active material. The negative electrode active material, styrene-butadiene rubber dispersion, and carboxymethylcellulose sodium were mixed in a solid content mass ratio of 98:1:1, and a negative electrode mixture slurry was prepared using water as the dispersion medium. This slurry was applied to a negative electrode core made of a long copper foil with a thickness of 8 μm, and the coating film was dried and compressed to obtain a negative electrode in which a negative electrode mixture layer was formed on the negative electrode core. At this time, a non-composite portion of the negative electrode mixture layer was provided at one end in the width direction of the negative electrode.

[0088] [Preparation of non-aqueous electrolyte] 100 parts by mass of a mixed solvent prepared by mixing ethylene carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 3:7, to which 5 parts by mass of vinylene carbonate (VC) is added, and LiPF ６ A non-aqueous electrolyte was prepared by dissolving 1.5 mol / liter of [the substance].

[0089] [Preparation of Test Cell] The positive electrode, the negative electrode, and a polyethylene separator were wound in a spiral shape using a cylindrical winding core to obtain an electrode body. A positive electrode current collector plate and a negative electrode current collector plate were then placed on the upper and lower ends of the prepared electrode body. The portion of the positive electrode at the upper end of the electrode body where the composite layer was not formed, and the portion of the negative electrode at the lower end of the electrode body where the composite layer was not formed, were bent radially inward and welded to the positive electrode current collector plate and the negative electrode current collector plate, respectively. At this time, the portion of the positive electrode where the composite layer was not formed was bent radially inward starting from the boundary between the insulating layer formed portion and the core body exposed portion. Subsequently, the electrode body was housed in a bottomed cylindrical outer container, the negative electrode current collector plate was welded to the bottom of the bottomed cylindrical outer container, and the positive electrode current collector plate and the sealing body were connected with a positive electrode lead.

[0090] [Evaluation of Injection Time] For the test cells prepared as described above, a predetermined amount of non-aqueous electrolyte was injected into the outer casing. The time it took for the non-aqueous electrolyte to permeate the electrode body and for the liquid level to fall below the positive electrode current collector plate was evaluated as the injection time.

[0091] [Evaluation of Cycle Characteristics (Capacity Retention Rate)] The test cell, after being injected with the above-mentioned fluid, had its opening in the outer container sealed with a sealing body via a gasket. The prepared test cell was then charged to 4.2V with a constant current of 0.5C at a temperature of 25°C, and then charged at a constant voltage of 4.2V until the current value was equivalent to 0.01C. After that, it was discharged to 2.5V with a constant current of 0.5C. This was considered one cycle, and the discharge capacity at 0.5C after 1000 cycles was measured. The capacity retention rate was then calculated using the following formula: Capacity retention rate [%] = (Discharge capacity after 1000 cycles / Discharge capacity in the first cycle) × 100

[0092] <Example 2> A test cell was prepared and evaluated in the same manner as in Example 1, except that the insulating layer was formed so that the arrangement of the insulating layer formation section was as shown in Figure 6.

[0093] <Example 3> A test cell was prepared and evaluated in the same manner as in Example 1, except that the insulating layer was formed so that the arrangement of the insulating layer formation section was as shown in Figure 8.

[0094] <Example 4> A test cell was prepared and evaluated in the same manner as in Example 1, except that the insulating layer was formed so that the arrangement of the insulating layer formation section was as shown in Figure 10.

[0095] <Example 5> A test cell was prepared and evaluated in the same manner as in Example 1, except that the insulating layer was formed so that the arrangement of the insulating layer formation section was as shown in Figure 12.

[0096] <Example 6> A test cell was prepared and evaluated in the same manner as in Example 1, except that the insulating layer was formed so that the arrangement of the insulating layer formation section was as shown in Figure 14.

[0097] <Example 7> A test cell was prepared and evaluated in the same manner as in Example 1, except that the insulating layer was formed so that the arrangement of the insulating layer formation section was as shown in Figure 16.

[0098] <Example 8> A test cell was prepared and evaluated in the same manner as in Example 1, except that the insulating layer was formed so that the arrangement of the insulating layer formation section was as shown in Figure 18.

[0099] <Comparative Example 1> A test cell was prepared and evaluated in the same manner as in Example 1, except that the insulating layer was formed so that the arrangement of the insulating layer formation portion was as shown in Figure 21. In other words, the width of the insulating layer formation portion of the positive electrode in Comparative Example 1 is uniform along the longitudinal direction of the positive electrode. The width of the insulating layer formation portion was set to 3 mm.

[0100] Table 1 shows the injection time and volume retention rate of the test cells for each example and comparative example. The injection time is shown relative to the injection time of Comparative Example 1, which is set to 100. A smaller value indicates a shorter injection time and better productivity.

[0101]

[0102] As shown in Table 1, the liquid injection time for the test cells of Examples 1 to 8 was shorter than that for the test cell of Comparative Example 1. This is presumed to be because changing the folding position of the non-compound layer portion in the longitudinal direction of the positive electrode created an injection path for the non-aqueous electrolyte. Furthermore, the capacity retention rate of the test cells of Examples 1 to 5 was improved compared to that of the test cell of Comparative Example 1. This is presumed to be because changing the folding position of the non-compound layer portion in the longitudinal direction of the positive electrode created a diffusion path for the non-aqueous electrolyte inside the battery, improving the circulation of the liquid inside the electrode body.

[0103] This disclosure will be further described by the following embodiments. Configuration 1: A non-aqueous electrolyte secondary battery comprising an electrode body in which a first electrode and a second electrode having opposite polarities are wound longitudinally via a separator, a non-aqueous electrolyte, and an outer container for housing the electrode body and the non-aqueous electrolyte, wherein the first electrode has a first electrode core and a first electrode mixture layer disposed on the first electrode core, and a non-composite mixture layer portion is provided at one end of the first electrode in the width direction, the non-composite mixture layer portion has an insulating layer forming portion on the first electrode core and an exposed core portion provided on one side of the first electrode in the width direction from the insulating layer forming portion, the non-composite mixture layer portion has an insulating layer forming portion on the first electrode core and an exposed core portion, the non-aqueous electrolyte secondary battery is bent radially starting from the boundary between the insulating layer forming portion and the exposed core portion, and the width of the insulating layer forming portion differs in the longitudinal direction of the first electrode. Configuration 2: The non-aqueous electrolyte secondary battery according to Configuration 1, wherein the insulating layer forming portion has a region in which the width of the insulating layer forming portion continuously increases or decreases from the winding start side to the winding end side of the first electrode. Configuration 3: The non-aqueous electrolyte secondary battery according to Configuration 1 or 2, wherein the maximum width of the insulating layer forming portion is 2 times or more and 10 times or less the minimum width of the insulating layer forming portion. Configuration 4: The non-aqueous electrolyte secondary battery according to any one of Configurations 1 to 3, wherein the maximum width of the insulating layer forming portion is 40% or more and 80% or less the width of the non-compound layer forming portion. Configuration 5: The non-aqueous electrolyte secondary battery according to any one of Configurations 1 to 4, wherein the minimum width of the insulating layer forming portion is 5% or more and 20% or less the width of the non-compound layer forming portion. Configuration 6: The non-aqueous electrolyte secondary battery according to any one of Configurations 1 to 5, wherein the thickness of the insulating layer is smaller than the thickness of one side of the first electrode compound layer. Configuration 7: A non-aqueous electrolyte secondary battery according to any one of Configurations 1 to 6, wherein the thickness of the insulating layer is 10 μm or more and 50 μm or less. Configuration 8: A non-aqueous electrolyte secondary battery according to any one of Configurations 1 to 7, wherein the first electrode is the positive electrode and the second electrode is the negative electrode.

[0104] 10 Non-aqueous electrolyte secondary battery, 11 Positive electrode (first electrode), 11X Winding start end, 11Y Winding end, 12 Negative electrode (second electrode), 13 Separator, 14 Electrode body, 15 Outer can, 16 Sealing body, 17 Positive electrode current collector plate, 18 Negative electrode current collector plate, 19 Insulating plate, 20 Positive electrode lead, 21 Grooved section, 22 Filter, 23 Lower valve body, 24 Insulating member, 25 Upper valve body, 26 Cap, 26a Through hole, 27 Gasket, 30 Positive electrode core body (first electrode core body), 31 Positive electrode mixture layer (first electrode mixture layer), 32 Mixture layer non-formed section, 33 Insulating layer formed section, 33A First region, 33B Second region, 34 Core body exposed section, 35, 35A, 35B, 35C, 35D Change point, 40 Negative electrode core, 41 Negative electrode mixture layer, 42 Non-mixing layer area, 50 Insulating layer

Claims

1. A non-aqueous electrolyte secondary battery comprising: an electrode body in which a first electrode and a second electrode having opposite polarities are wound longitudinally via a separator; a non-aqueous electrolyte; and an outer container for housing the electrode body and the non-aqueous electrolyte, wherein the first electrode comprises a first electrode core and a first electrode mixture layer disposed on the first electrode core, and a non-composite mixture layer portion is provided at one end of the first electrode in the width direction, wherein the non-composite mixture layer portion comprises an insulating layer forming portion on the first electrode core and a core body exposed portion provided on one side of the first electrode in the width direction from the insulating layer forming portion, and is bent radially starting from the boundary between the insulating layer forming portion and the core body exposed portion, and the width of the insulating layer forming portion differs in the longitudinal direction of the first electrode.

2. The non-aqueous electrolyte secondary battery according to claim 1, wherein the insulating layer forming portion has a region in which the width of the insulating layer forming portion continuously increases or decreases from the winding start side to the winding end side of the first electrode.

3. The non-aqueous electrolyte secondary battery according to claim 1, wherein the maximum width of the insulating layer forming portion is 1.5 times or more and 10 times or less the minimum width of the insulating layer forming portion.

4. The non-aqueous electrolyte secondary battery according to claim 1, wherein the maximum width of the insulating layer forming portion is 40% or more and 80% or less of the width of the non-composite layer forming portion.

5. The minimum width of the insulating layer forming portion is 5% or more and 40% or less of the width of the non-compound layer forming portion, as described in claim 1.

6. The non-aqueous electrolyte secondary battery according to claim 1, wherein the thickness of the insulating layer is smaller than the thickness of one side of the first electrode mixture layer.

7. The non-aqueous electrolyte secondary battery according to claim 1, wherein the thickness of the insulating layer is 10 μm or more and 50 μm or less.

8. The non-aqueous electrolyte secondary battery according to claim 1, wherein the first electrode is a positive electrode and the second electrode is a negative electrode.

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