Nonaqueous electrolyte secondary battery

Abstract

Provided is a nonaqueous electrolyte secondary battery in which deformation of a negative electrode is suppressed. A non-aqueous electrolyte secondary battery according to one embodiment of the present application is provided with: a wound electrode body in which a positive electrode and a negative electrode are wound with a separator interposed therebetween; and an exterior body that accommodates the electrode body. The negative electrode has a belt-shaped negative electrode current collector and negative electrode mixture layers formed on both surfaces of the negative electrode current collector. The positive electrode includes a strip-shaped positive electrode current collector and positive electrode mixture layers formed on both surfaces of the positive electrode current collector, and a positive electrode exposed portion in which the positive electrode current collector is exposed is formed on a winding inner side of a winding start end portion of the positive electrode. A first insulating tape is bonded to the winding inner side of the positive electrode so as to straddle the winding start end of the positive electrode mixture layer.

Description

Technical Field

[0001] The present application relates to a non-aqueous electrolyte secondary battery. Background Art

[0002] Conventionally, a non-aqueous electrolyte secondary battery in which a wound electrode body formed by winding a strip-shaped positive electrode and a negative electrode with a separator interposed therebetween is housed in an outer package has been widely used. In Patent Document 1, in order to prevent an internal short circuit caused by burrs on the positive electrode and the negative electrode of a secondary battery having a wound electrode body, a method of attaching an insulating tape to the surface of the positive electrode or the negative electrode at a position where an internal short circuit is assumed is disclosed.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2002-42881 Summary of the Invention

[0006] However, in a secondary battery in which a wound electrode body is housed in an outer package, when the electrode body expands during charge and discharge cycles, pressure is applied to the electrode body from the outer package. At this time, in the electrode body, the negative electrode facing the inner end portion of the winding of the positive electrode may be bent or deformed, and an internal short circuit may occur. The technique disclosed in Patent Document 1 does not consider the deformation of the negative electrode when the electrode body expands, and there is still room for improvement.

[0007] An object of the present application is to provide a non-aqueous electrolyte secondary battery that suppresses deformation of the negative electrode.

[0008] A non-aqueous electrolyte secondary battery according to one aspect of the present application is characterized in that it includes a wound electrode body formed by winding a positive electrode and a negative electrode with a separator interposed therebetween, and an outer package for housing the electrode body. The negative electrode has a strip-shaped negative electrode current collector and negative electrode mixture layers formed on both surfaces of the negative electrode current collector, and includes a non-facing portion wound from the start end of winding in a state where it does not face the positive electrode with the separator interposed therebetween. The positive electrode has a strip-shaped positive electrode current collector and positive electrode mixture layers formed on both surfaces of the positive electrode current collector. A positive electrode exposed portion exposing the positive electrode current collector is formed on the inner side of the start end of winding of the positive electrode, and a first insulating tape is attached to the inner side of the winding of the positive electrode so as to cross the start end of the winding of the positive electrode mixture layer.

[0009] According to the non-aqueous electrolyte secondary battery of the present application, deformation of the negative electrode, which may be a cause of an internal short circuit, can be suppressed. Brief Description of the Drawings

[0010] Figure 1 It is an axial sectional view of a cylindrical secondary battery as an example of an embodiment.

[0011] Figure 2 is Figure 1 A perspective view of a wound electrode body included in the secondary battery shown.

[0012] Figure 3 A cross-sectional view showing the positional relationship between the positive electrode and the negative electrode of the electrode body constituting an example of the embodiment in an unfolded state.

[0013] Figure 4 A cross-sectional view in which the vicinity of the winding start end of the positive electrode in another example of the embodiment is enlarged.

[0014] Figure 5 A radial cross-sectional view near the winding central axis of the electrode body in an example of the embodiment. Detailed implementation manners

[0015] Hereinafter, with reference to the accompanying drawings, an example of an embodiment of a cylindrical secondary battery of the present application will be described in detail. In the following description, specific shapes, materials, numerical values, directions, etc. are examples for facilitating the understanding of the present application and can be appropriately changed in accordance with the specifications of the cylindrical secondary battery. In addition, in the following description, in the case of including a plurality of embodiments and modification examples, it is assumed from the beginning that their characteristic parts are appropriately combined and used. It should be noted that in this specification, "~" means a range including the upper and lower limits before and after "~".

[0016] Figure 1 An axial cross-sectional view of a cylindrical secondary battery 10 as an example of the embodiment. Figure 1 In the secondary battery 10 shown, an electrode body 14 and a non-aqueous electrolyte (not shown) are housed in an outer package 15. The electrode body 14 has a wound structure in which a positive electrode 11 and a negative electrode 12 are wound with a spacer 13 interposed therebetween. As the non-aqueous solvent (organic solvent) of the non-aqueous electrolyte, carbonates, lactones, ethers, ketones, esters, etc. can be used, and two or more of these solvents can be mixed and used. In the case of mixing two or more solvents, a mixed solvent containing a cyclic carbonate and a chain carbonate is preferably used. For example, ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), etc. can be used as the cyclic carbonate, and dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), etc. can be used as the chain carbonate. As the electrolyte salt of the non-aqueous electrolyte, LiPF6, LiBF4, LiCF3SO3, etc. and their mixtures can be used. The dissolution amount of the electrolyte salt with respect to the non-aqueous solvent can be set to 0.5 to 2.0 mol / L, for example. It should be noted that hereinafter, for the convenience of description, the side of the sealing body 16 is set as "upper" and the bottom side of the outer package 15 is set as "lower" for description.

[0017] The opening of the outer package 15 is sealed by a sealing body 16, thereby sealing the interior of the secondary battery 10. Insulating plates 17 and 18 are respectively provided above and below the electrode body 14. The positive electrode lead 19 passes through the through hole of the insulating plate 17 and extends upward, and is welded to the lower surface of the filter sheet 22 which is the bottom plate of the sealing body 16. In the secondary battery 10, the lid 26 which is the top plate of the sealing body 16 and is electrically connected to the filter sheet 22 becomes the positive terminal. On the other hand, the negative electrode lead 20 passes through the through hole of the insulating plate 18 and extends toward the bottom side of the outer package 15, and is welded to the inner surface of the bottom of the outer package 15. In the secondary battery 10, the outer package 15 becomes the negative terminal. It should be noted that when the negative electrode lead 20 is provided near the winding end, the negative electrode lead 20 passes outside the insulating plate 18 and extends toward the bottom side of the outer package 15, and is welded to the inner surface of the bottom of the outer package 15.

[0018] The outer package 15 is, for example, a metal outer package can in the shape of a bottomed cylinder. A gasket 27 is provided between the outer package 15 and the sealing body 16 to ensure the airtightness of the interior of the secondary battery 10. The outer package 15 has, for example, a grooved portion 21 that supports the sealing body 16 and is formed by pressing the side surface from the outside. The grooved portion 21 is preferably formed in a ring shape along the circumferential direction of the outer package 15, and the sealing body 16 is supported by its upper surface.

[0019] The sealing body 16 has a filter sheet 22, a lower valve body 23, an insulating member 24, an upper valve body 25, and a lid 26 that are laminated in sequence from the side of the electrode body 14. Each member constituting the sealing body 16 has, for example, a disc shape or an annular shape, and the members other than the insulating member 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 insulating member 24 is interposed between their respective peripheral portions. When the internal pressure of the battery rises due to abnormal heating, for example, the lower valve body 23 breaks, whereby the upper valve body 25 bulges toward the lid 26 side and separates from the lower valve body 23, thereby blocking the electrical connection between the two. When the internal pressure further rises, the upper valve body 25 breaks, and gas is discharged from the opening 26a of the lid 26.

[0020] Next, the electrode body 14 will be described while referring to Figure 2 the following. Figure 2It is a perspective view of the electrode body 14. As shown above, the electrode body 14 has a wound structure in which the positive electrode 11 and the negative electrode 12 are wound in a spiral shape with a spacer 13 interposed therebetween. The positive electrode 11, the negative electrode 12, and the spacer 13 are all formed in a strip shape and wound in a spiral shape around the winding axis, thereby being in a state of being alternately laminated in the radial direction β of the electrode body 14. In the radial direction β, the side closer to the winding axis is called the winding inner side, and the opposite side is called the winding outer side. In the electrode body 14, the length direction of the positive electrode 11 and the negative electrode 12 becomes the winding direction γ, and the width direction of the positive electrode 11 and the negative electrode 12 becomes the axial direction α. In the winding direction γ, the side closer to the winding axis is called the winding start side, and the opposite side is called the winding end side. In addition, in the positive electrode 11, the negative electrode 12, and the first insulating tape 50 and the second insulating tape 52 described later, the end on the winding start side is called the winding start end, and the end on the winding end side is called the winding end end. The positive electrode lead 19 extends in the axial direction α approximately at the center in the radial direction from the center to the outermost periphery at the upper end of the electrode body 14. In addition, the negative electrode lead 20 extends in the axial direction α from the vicinity of the winding axis at the lower end of the electrode body 14.

[0021] The spacer 13 is, for example, a porous sheet having ion permeability and insulation. Specific examples of the porous sheet include microporous films, woven fabrics, non-woven fabrics, etc. Suitable materials for the spacer are olefin resins such as polyethylene and polypropylene, cellulose, etc. The spacer 13 can also be a laminate having a cellulose fiber layer and a thermoplastic resin fiber layer such as an olefin resin. In addition, it can be a multi-layer spacer including a polyethylene layer and a polypropylene layer, or a spacer in which a material such as an aromatic polyamide resin or a ceramic is coated on the surface of the spacer 13.

[0022] Next, while referring to Figures 3 to 5 the positive electrode 11 and the negative electrode 12 constituting the electrode body 14 will be described in detail. Figure 3 It is a cross-sectional view showing the positional relationship between the positive electrode 11 and the negative electrode 12 of the electrode body 14 constituting an example of the embodiment in an unfolded state.

[0023] The positive electrode 11 has a strip-shaped positive electrode current collector 30, a positive electrode mixture layer 31 formed on the winding inner side of the positive electrode current collector 30, and a positive electrode mixture layer 32 formed on the winding outer side of the positive electrode current collector 30. The positive electrode current collector 30 is, for example, a foil of a metal such as aluminum or a film having the metal disposed on the surface layer. A suitable positive electrode current collector 30 is a foil of a metal having aluminum or an aluminum alloy as the main component. The thickness of the positive electrode current collector 30 is, for example, 10 μm to 30 μm.

[0024] The positive electrode mixture layers 31 and 32 are formed on both sides of the positive electrode current collector 30 in all regions except for the positive electrode exposed portion 34. The positive electrode exposed portion 34 is the portion of the surface of the positive electrode current collector 30 that is not covered by the positive electrode mixture layers 31 and 32. The positive electrode mixture layers 31 and 32 preferably contain a positive electrode active material, a conductive agent, and a binder. After coating a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, a binder, and a solvent such as N-methyl-2-pyrrolidone (NMP) on both sides of the positive electrode current collector 30, drying and calendering are performed, thereby fabricating the positive electrode 11. The positive electrode exposed portion 34 is provided, for example, by intermittent coating in which the positive electrode mixture slurry is not coated on a part of the positive electrode current collector 30.

[0025] As the positive electrode active material, a lithium-containing transition metal oxide containing transition metal elements such as Co, Mn, and Ni can be used. The lithium-containing transition metal oxide is not particularly limited, and is preferably a composite oxide represented by the general formula Li 1＋x MO2 (wherein, -0.2 < x ≤ 0.2, and M contains at least one of Ni, Co, Mn, and Al).

[0026] As the conductive agent contained in the positive electrode mixture layers 31 and 32, for example, carbon black (CB) such as acetylene black (AB) and Ketjen black, carbon materials such as graphite, etc. are used. As the binder contained in the positive electrode mixture layers 31 and 32, for example, fluorine-based resins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyimide (PI), acrylic resins, polyolefin resins, etc. are used. In addition, these resins can be used in combination with carboxymethyl cellulose (CMC) or its salts, polyethylene oxide (PEO), etc. They can be used alone or in combination of two or more.

[0027] The negative electrode 12 has a strip-shaped negative electrode current collector 40 and negative electrode mixture layers 42 formed on both sides of the negative electrode current collector 40. The negative electrode current collector 40 is, for example, a foil of a metal such as copper, or a film having the metal disposed on the surface layer. The thickness of the negative electrode current collector 40 is, for example, 5 μm to 30 μm.

[0028] The negative electrode mixture layers 42 are formed on both sides of the negative electrode current collector 40 in all regions except for the negative electrode exposed portion 44. The negative electrode exposed portion 44 is the portion of the surface of the negative electrode current collector 40 that is not covered by the negative electrode mixture layers 42. The negative electrode mixture layers 42 preferably contain a negative electrode active material and a binder. For example, after coating a negative electrode mixture slurry containing a negative electrode active material, a binder, and water, etc. on both sides of the negative electrode current collector 40, drying and calendering are performed, thereby fabricating the negative electrode 12. The negative electrode exposed portion 44 is provided, for example, by intermittent coating in which the negative electrode mixture slurry is not coated on a part of the negative electrode current collector 40.

[0029] As the negative electrode active material, there is no particular limitation as long as it can reversibly store and release lithium ions. For example, carbon materials such as natural graphite and artificial graphite, metals that alloy with lithium such as Si and Sn, or alloys, oxides, etc. containing them can be used.

[0030] As the binder contained in the negative electrode binder layer 42, for example, the same resin as in the case of the positive electrode 11 can be used. When preparing the negative electrode binder slurry using an aqueous solvent, styrene-butadiene rubber (SBR), CMC or its salt, polyacrylic acid or its salt, polyvinyl alcohol, etc. can be used. They can be used alone or in combination of two or more.

[0031] As Figure 3 shown, the length of the negative electrode 12 in the length direction γ is greater than the length of the positive electrode 11 in the length direction γ. The winding start end 12s of the negative electrode 12 is located on the winding start side compared to the winding start end 11s of the positive electrode 11, and the winding end of the negative electrode 12 is located on the winding end side compared to the winding end of the positive electrode 11. In addition, although Figure 3 not shown in, the length of the negative electrode 12 in the width direction (axial direction) α is greater than the length of the positive electrode 11 in the width direction α. Thus, since at least the portion of the positive electrode 11 where the positive electrode binder layers 31 and 32 are formed is disposed opposite to the portion of the negative electrode 12 where the negative electrode binder layer 42 is formed with the spacer 13 interposed therebetween, precipitation of lithium in the negative electrode 12 can be prevented.

[0032] A positive electrode exposed portion 34 exposing the positive electrode current collector 30 is formed on the inner side of the winding of the winding start end portion of the positive electrode 11 including the winding start end 11s. On the inner side of the winding of the positive electrode 11, the first insulating tape 50 is adhered so as to straddle the winding start end 31s of the positive electrode binder layer 31. Thus, deformation of the negative electrode 12 caused by contact between the winding start end 11s of the positive electrode 11 and the negative electrode 12 can be suppressed. It is presumed that by reducing the thickness of the winding start end 11s of the positive electrode 11 and imparting elasticity to the winding start end 11s using the first insulating tape 50, the pressure exerted on the negative electrode 12 by the winding start end 11s of the positive electrode 11 is reduced. The positive electrode exposed portion 34 is preferably wound 0.05 to 1.25 turns, more preferably 0.08 to 0.8 turns, and particularly preferably 0.1 to 0.5 turns with respect to the winding center axis of the electrode body 14. The adhesion range of the first insulating tape 50 is, for example, 0.2 to 0.8 turns. The winding start end 50s of the first insulating tape 50 is preferably facing the winding start end 11s of the positive electrode 11.

[0033] The positive electrode exposed portion 34 formed at the winding start end portion of the positive electrode 11 preferably does not connect the positive electrode lead 19 to the positive electrode current collector 30. Figure 3In the example shown, a positive electrode exposed portion 34 is also provided at approximately the center in the longitudinal direction γ of the positive electrode 11. At this positive electrode exposed portion 34, the positive electrode lead 19 is joined to the positive electrode current collector 30. Thereby, the current collecting property is improved. In addition, the positive electrode exposed portion 34 to which the positive electrode lead is joined is preferably provided on both surfaces of the positive electrode 11 so as to overlap in the thickness direction of the positive electrode 11. The positive electrode exposed portion 34 is preferably covered with a third insulating tape 54 having the same configuration as the first insulating tape 50 and the second insulating tape 52 described later.

[0034] Figure 3 In the example shown, a positive electrode mixture layer 32 is formed from the outer side of the winding of the positive electrode 11 up to the winding start end 11s. Thereby, high capacity of the battery can be achieved.

[0035] The form of the winding start end 11s of the positive electrode 11 is not limited to Figure 3 the example. Figure 4 is a cross-sectional view showing an enlarged view of the vicinity of the winding start end 11s of the positive electrode 11 in another example of the embodiment. As Figure 4 shown, a positive electrode exposed portion 34 can be further formed on the outer side of the winding of the positive electrode 11 at the winding start end portion. On the outer side of the winding of the positive electrode 11, the first insulating tape 50 is attached so as to straddle the winding start end 32s of the positive electrode mixture layer 32. Thereby, since the rigidity of the winding start end 11s of the positive electrode 11 is reduced, deformation of the negative electrode 12 can be more significantly suppressed. The first insulating tape 50 attached to the outer winding surface of the positive electrode 11 is attached, for example, at a position facing the first insulating tape 50 attached to the inner winding surface.

[0036] The winding start end 31s of the positive electrode mixture layer 31 on the inner side of the winding of the positive electrode 11 and the winding start end 32s of the positive electrode mixture layer 32 on the outer side of the winding of the positive electrode 11 can face each other with the positive electrode current collector 30 interposed therebetween, however, it is preferably as Figure 4 shown not to face each other. More preferably, the winding start end 31s is located on the winding end side compared to the winding start end 32s.

[0037] Next, while referring to Figure 3 the negative electrode 12 will be described. The negative electrode 12 includes a non-opposing portion 12a wound from the winding start end 12s in a state not facing the positive electrode 11 with the spacer 13 interposed therebetween. The non-opposing portion 12a has a negative electrode mixture layer forming portion 42a in which a negative electrode mixture layer 42 is continuously formed from the winding end side to the winding start side. The negative electrode mixture layer forming portion 42a is preferably wound for 0.25 turns or more. Since the negative electrode mixture layer forming portion 42a has higher strength than the negative electrode exposed portion 44, it is wound to form a cylindrical exhaust passage, and in the case where gas is generated inside the secondary battery 10, exhaust can be effectively performed.

[0038] The non-opposing part 12a has, for example, a negative electrode exposed part 44 on the winding start side compared to the winding start end 42s of the negative electrode mixture layer forming part 42a. At the negative electrode exposed part 44, the negative electrode lead 20 is joined to the negative electrode current collector 40. The negative electrode exposed part 44 is provided, for example, on both surfaces of the negative electrode 12 so as to overlap in the thickness direction of the negative electrode 12. It should be noted that the arrangement position of the negative electrode lead 20 is not limited to Figure 3 the example shown. The negative electrode lead 20 may also be provided only near the winding end of the negative electrode 12. Additionally, the negative electrode lead 20 may be provided near both the winding start end and the winding end of the negative electrode 12. In this case, the current collection property is improved. The negative electrode exposed part 44 may also be formed at the winding end of the negative electrode 12, and the negative electrode exposed part 44 may be brought into contact with the inner peripheral surface of the outer package 15 (refer to Figure 1 ), whereby the vicinity of the winding end of the negative electrode 12 is electrically connected to the outer package 15 without using the negative electrode lead 20.

[0039] On the winding outer surface of the negative electrode 12, the second insulating tape 52 may be attached so as to straddle the opposing part 12f of the winding start end 11s of the positive electrode 11. The winding end 52e of the second insulating tape 52 is arranged on the winding start side compared to the winding end 50e of the first insulating tape. Thereby, lithium precipitation on the surface of the negative electrode 12 can be suppressed around the winding end 52e of the second insulating tape 52. In addition, the second insulating tape 52 may be attached to the winding inner surface of the negative electrode 12. The second insulating tape 52 attached to the winding inner surface is attached, for example, at a position facing the second insulating tape 52 attached to the winding outer surface.

[0040] The second insulating tape 52 may be attached so as to straddle the negative electrode lead 20. Thereby, the second insulating tape 52 suppresses an internal short circuit in the negative electrode lead 20. It should be noted that the negative electrode lead 20 may also be covered with another insulating tape other than the second insulating tape 52. This insulating tape has, for example, the same configuration as the second insulating tape 52.

[0041] The first insulating tape 50 and the second insulating tape 52 are insulating tapes. The first insulating tape 50 and the second insulating tape 52 may have different configurations from each other, but preferably have the same configuration. Hereinafter, assuming that the first insulating tape 50 and the second insulating tape 52 have the same configuration, the configuration of the insulating tape referring to both the first insulating tape 50 and the second insulating tape 52 will be described.

[0042] In the width direction α, the width of the insulating tape may be greater than the widths of the positive electrode 11 and the negative electrode 12. Thereby, since the entire width direction α of the positive electrode 11 and the negative electrode 12 can be covered, an internal short circuit can be more reliably suppressed.

[0043] The insulating tape, for example, has a base material layer and an adhesive layer formed on the surface of the base material layer. The thickness of the insulating tape is, for example, 20 μm to 70 μm, preferably 25 μm to 60 μm. The thickness of the insulating tape and each layer can be measured by cross-sectional observation using a scanning electron microscope (SEM).

[0044] The base material layer may contain an organic material and an inorganic material. The main component of the organic material contained in the base material layer is preferably a resin with excellent insulation, electrolyte resistance, heat resistance, puncture strength, etc. Specifically, the main component of the base material layer is preferably set as a resin such as polypropylene (PP). It should be noted that the main component of the base material layer can also be an ester-based resin such as polyethylene terephthalate (PET), polyimide (PI), polyphenylene sulfide, polyamide, etc. These resins can be used alone or in combination of two or more. From the perspective of hardness, the main component of the base material layer is preferably PI. On the other hand, PP is inexpensive and easy to obtain, and in addition, it has sufficient rigidity as the base material layer at the above thickness, so from the perspective of cost, the main component of the base material layer is preferably PP. The thickness of the base material layer is, for example, 10 μm to 45 μm, preferably 15 μm to 35 μm. The thickness of the base material layer is preferably greater than the thickness of the adhesive layer.

[0045] The adhesive layer is a layer for imparting adhesiveness to the positive electrode 11 to the insulating tape. An adhesive material such as an adhesive is coated on one surface of the base material layer to form the adhesive layer. The adhesive layer can be composed of an adhesive (resin) with excellent insulation, electrolyte resistance, etc. The adhesive constituting the adhesive layer can be a hot melt type that exhibits adhesiveness by heating or a thermosetting type that cures by heating. However, from the perspective of productivity, etc., an adhesive with adhesiveness at room temperature is preferred. The adhesive layer is, for example, composed of an acrylic-based adhesive or a synthetic rubber-based adhesive. The thickness of the adhesive layer is, for example, 5 μm to 30 μm.

[0046] It should be noted that the insulating tape is not limited to a two-layer structure. For example, it can also be a three-layer structure in which an inorganic particle-containing layer is formed between the base material layer and the adhesive layer. By using such a three-layer structure, the heat resistance of the insulating tape can be improved. The inorganic particle-containing layer preferably has a layer structure in which inorganic particles are dispersed in the resin matrix of the constituent layer. The resin constituting the inorganic particle-containing layer is preferably excellent in insulation, electrolyte resistance, etc., and has good adhesiveness to the inorganic particles and the base material layer. As suitable resins, acrylic resins, urethane resins, and copolymers thereof can be exemplified. They can be used alone or in combination of two or more. For example, a resin solution containing inorganic particles is coated on one surface of the base material layer to form the inorganic particle-containing layer. The thickness of the inorganic particle-containing layer is, for example, 0.5 μm to 10 μm, preferably 1 μm to 5 μm.

[0047] Next, with reference toFigure 5 Meanwhile, the bonding range of the second insulating tape 52 in the non-opposing portion 12a will be described. Figure 5 It is a radial cross-sectional view near the winding central axis O of the electrode body 14 which is an example of the embodiment. The second insulating tape 52 is preferably bonded so as to straddle the winding start end 42s of the negative electrode mixture layer forming portion 42a. Thereby, the deformation of the negative electrode 12 can be more significantly suppressed. The second insulating tape 52 may also be bonded to the position covering the winding start end 12s of the negative electrode 12.

[0048] As described above, in the non-aqueous electrolyte secondary battery according to the present application, by reducing the rigidity of the winding start end 11s of the positive electrode 11, the deformation of the negative electrode 12 can be suppressed.

[0049] The present invention can be further illustrated by the following embodiments.

[0050] Constitution 1:

[0051] A non-aqueous electrolyte secondary battery includes a wound electrode body in which a positive electrode and a negative electrode are wound with a spacer therebetween, and an outer packaging body that houses the electrode body.

[0052] The negative electrode has a strip-shaped negative electrode current collector and negative electrode mixture layers formed on both surfaces of the negative electrode current collector, and includes a non-opposing portion that is wound from the winding start end in a state where it does not face the positive electrode with the spacer therebetween.

[0053] The positive electrode has a strip-shaped positive electrode current collector and positive electrode mixture layers formed on both surfaces of the positive electrode current collector.

[0054] A positive electrode exposed portion exposing the positive electrode current collector is formed on the inner side of the winding of the winding start end portion of the positive electrode.

[0055] On the inner side of the winding of the positive electrode, a first insulating tape is bonded so as to straddle the winding start end of the positive electrode mixture layer.

[0056] Constitution 2:

[0057] According to the non-aqueous electrolyte secondary battery described in Constitution 1, a positive electrode exposed portion is formed on the outer side of the winding of the winding start end portion of the positive electrode.

[0058] On the outer side of the winding of the positive electrode, the first insulating tape is bonded so as to straddle the winding start end of the positive electrode mixture layer.

[0059] Constitution 3:

[0060] The non-aqueous electrolyte secondary battery according to Configuration 2, wherein the start end of the positive electrode mixture layer on the inner side of the winding of the positive electrode does not face the start end of the positive electrode mixture layer on the outer side of the winding of the positive electrode.

[0061] Configuration 4:

[0062] The non-aqueous electrolyte secondary battery according to Configuration 1, wherein the positive electrode mixture layer is formed on the outer side of the winding of the positive electrode up to the start end of the winding of the positive electrode.

[0063] Configuration 5:

[0064] The non-aqueous electrolyte secondary battery according to any one of Configurations 1 to 4, wherein at the positive electrode exposed portion formed at the start end portion of the winding of the positive electrode, the positive electrode current collector is not joined with the positive electrode lead wire.

[0065] Configuration 6:

[0066] The non-aqueous electrolyte secondary battery according to any one of Configurations 1 to 5, wherein the non-facing portion has a negative electrode mixture layer forming portion in which the negative electrode mixture layer is continuously formed from the winding end side to the winding start side,

[0067] The negative electrode mixture layer forming portion is wound for 0.25 turns or more.

[0068] Configuration 7:

[0069] The non-aqueous electrolyte secondary battery according to any one of Configurations 1 to 6, wherein a second insulating tape is attached to the outer surface of the winding of the negative electrode so as to straddle the facing portion with the start end of the winding of the positive electrode,

[0070] The winding end of the second insulating tape is arranged on the winding start side with respect to the winding end of the first insulating tape.

[0071] Configuration 8:

[0072] The non-aqueous electrolyte secondary battery according to Configuration 7, wherein the non-facing portion has a negative electrode exposed portion in which the negative electrode current collector is exposed on the winding start side with respect to the start end of the winding of the negative electrode mixture layer forming portion,

[0073] At the negative electrode exposed portion, a negative electrode lead wire is joined to the negative electrode current collector,

[0074] The second insulating tape is attached so as to straddle the negative electrode lead wire.

[0075] Explanation of reference numerals

[0076] 10 Secondary battery, 11 Positive electrode, 11s Winding start end, 12 Negative electrode, 12a Non-opposing portion, 12f Opposing portion, 12s Winding start end, 13 Spacer, 14 Electrode body, 15 Outer packaging body, 16 Sealing body, 17, 18 Insulating plates, 19 Positive electrode lead, 20 Negative electrode lead, 21 Grooved portion, 22 Filter, 23 Lower valve body, 24 Insulating member, 25 Upper valve body, 26 Cover, 26a Opening portion, 27 Gasket, 30 Positive electrode current collector, 31, 32 Positive electrode mixture layer, 34 Positive electrode exposed portion, 40 Negative electrode current collector, 42 Negative electrode mixture layer, 42a Negative electrode mixture layer forming portion, 42s Winding start end, 44 Negative electrode exposed portion, 50 First insulating tape, 50e Winding end, 52 Second insulating tape, 52s Winding start end, 52e Winding end, O Winding central axis.

Claims

1. A non-aqueous electrolyte secondary battery includes a wound electrode body formed by winding a positive electrode and a negative electrode with a separator therebetween, and an outer package body housing the electrode body. The negative electrode has a strip-shaped negative electrode current collector and negative electrode mixture layers formed on both surfaces of the negative electrode current collector, and includes a non-facing portion wound from the start end of winding in a state where it does not face the positive electrode with the separator therebetween. The positive electrode has a strip-shaped positive electrode current collector and positive electrode mixture layers formed on both surfaces of the positive electrode current collector. A positive electrode exposed portion exposing the positive electrode current collector is formed on the inner side of winding at the start end of winding of the positive electrode. On the inner side of winding of the positive electrode, a first insulating tape is attached so as to cross the start end of winding of the positive electrode mixture layer.

2. The non-aqueous electrolyte secondary battery according to claim 1, wherein the positive electrode exposed portion is further formed on the outer side of winding at the start end of winding of the positive electrode. On the outer side of winding of the positive electrode, the first insulating tape is attached so as to cross the start end of winding of the positive electrode mixture layer.

3. The non-aqueous electrolyte secondary battery according to claim 2, wherein the start end of winding of the positive electrode mixture layer on the inner side of winding of the positive electrode and the start end of winding of the positive electrode mixture layer on the outer side of winding of the positive electrode do not face each other.

4. The non-aqueous electrolyte secondary battery according to claim 1, wherein the positive electrode mixture layer is formed on the outer side of winding of the positive electrode up to the start end of winding of the positive electrode.

5. The non-aqueous electrolyte secondary battery according to claim 1, wherein at the positive electrode exposed portion formed at the start end of winding of the positive electrode, a positive electrode lead is not joined to the positive electrode current collector.

6. The non-aqueous electrolyte secondary battery according to claim 1, wherein the non-facing portion has a negative electrode mixture layer forming portion where the negative electrode mixture layer is continuously formed from the winding end side to the winding start side. The negative electrode mixture layer forming portion is wound for 0.25 turns or more.

7. The non-aqueous electrolyte secondary battery according to claim 1, wherein on the outer winding surface of the negative electrode, a second insulating tape is attached so as to cross the facing portion with the start end of winding of the positive electrode. The winding end of the second insulating tape is arranged on the winding start side compared to the winding end of the first insulating tape.

8. The non-aqueous electrolyte secondary battery according to claim 7, wherein with respect to the non-facing portion, a negative electrode exposed portion exposing the negative electrode current collector is provided on the winding start side compared to the start end of winding of the negative electrode mixture layer forming portion. At the negative electrode exposed portion, a negative electrode lead is joined to the negative electrode current collector. The second insulating tape is attached so as to cross the negative electrode lead.

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