Non-aqueous electrolyte secondary battery, and method for manufacturing non-aqueous electrolyte secondary battery

Abstract

A non-aqueous electrolyte secondary battery comprising: an electrode body (14) in which an elongated positive electrode (11) and an elongated negative electrode (12) are wound with a separator (13) interposed therebetween; and a bottomed cylindrical outer can that accommodates the electrode body (14), wherein said non-aqueous electrolyte secondary battery is characterized in that the negative electrode (12) has a negative electrode current collector exposed portion (43) in which a negative electrode mixture layer (41) is not provided on at least the outer peripheral surface of the negative electrode current collector (40) and the negative electrode current collector (40) is exposed, the negative electrode current collector exposed portion (43) is provided on the outermost periphery of the electrode body (14), an adhesive layer (50) is provided on at least a portion of the inner peripheral surface of the negative electrode current collector exposed portion (43), and the negative electrode current collector exposed portion (43) is bonded to the negative electrode (12) facing the negative electrode current collector exposed portion (43) by the adhesive layer (50).

Description

Nonaqueous electrolyte secondary battery and method for manufacturing the same

[0001] The present disclosure relates to a non-aqueous electrolyte secondary battery and a method for manufacturing a non-aqueous electrolyte secondary battery.

[0002] In general, a nonaqueous electrolyte secondary battery includes an electrode assembly in which a strip-shaped positive electrode and a strip-shaped negative electrode are wound with a separator interposed therebetween, and an outer can housing the electrode assembly. Patent Document 1 discloses a nonaqueous electrolyte secondary battery in which a negative electrode current collector exposed portion, which exposes a negative electrode current collector made of copper foil or the like, is provided at the outermost periphery of the electrode assembly. By abutting the negative electrode current collector exposed portion on the inner surface of the outer can, the outer can serves as a negative electrode terminal. Patent Document 1 also discloses attaching tape to the negative electrode current collector exposed portion provided at the outermost periphery of the electrode assembly to fix the winding end of the negative electrode.

[0003] International Publication No. 2018 / 168628

[0004] When tape is applied to the exposed portion of the negative electrode current collector located at the outermost periphery to fix the winding end of the negative electrode, repeated charging and discharging tends to cause stress to concentrate at the edge of the tape due to an increase in the diameter of the electrode body caused by the expansion of the mixture layer during charging, which may result in damage such as cracking of the electrode plate near the edge of the tape.

[0005] A nonaqueous electrolyte secondary battery according to one aspect of the present disclosure is a nonaqueous electrolyte secondary battery including an electrode assembly in which a strip-shaped positive electrode and a strip-shaped negative electrode are wound with a separator interposed therebetween, and a bottomed cylindrical outer can that houses the electrode assembly, wherein the negative electrode has a negative electrode current collector exposed portion where the negative electrode current collector is exposed and no negative electrode mixture layer is provided on at least the outer peripheral surface of the negative electrode current collector, the negative electrode current collector exposed portion is provided on the outermost periphery of the electrode assembly, an adhesive layer is provided on at least a part of the inner peripheral surface of the negative electrode current collector exposed portion, and the negative electrode current collector exposed portion is bonded by the adhesive layer to the negative electrode that faces the negative electrode current collector exposed portion.

[0006] Furthermore, a manufacturing method for a nonaqueous electrolyte secondary battery according to one aspect of the present disclosure is characterized by comprising: an electrode body forming step of winding a strip-shaped positive electrode and a strip-shaped negative electrode with a separator interposed therebetween to form an electrode body; an adhesive layer forming step of forming an adhesive layer on the inner peripheral surface of a negative electrode current collector exposed portion where a negative electrode mixture layer is not provided on at least the outer peripheral surface of the negative electrode current collector; a slit forming step of forming a slit in the negative electrode, on a side of the negative electrode that is wound more inward than the adhesive layer and that extends along the width direction of the negative electrode; and a cutting step of inserting the electrode body, with the negative electrode current collector exposed portion bonded by the adhesive layer, into a bottomed cylindrical outer can, and then cutting the slit.

[0007] According to the nonaqueous electrolyte secondary battery of one aspect of the present disclosure, damage to the electrode plates caused by repeated charge and discharge can be suppressed.

[0008] Fig. 1 is an axial cross-sectional view of a non-aqueous electrolyte secondary battery according to an embodiment; Fig. 2 is a perspective view of an electrode body constituting the non-aqueous electrolyte secondary battery according to an embodiment; Fig. 3 is a radial cross-sectional view of a negative electrode in the vicinity of the outermost periphery of the electrode body; Fig. 4 is a perspective view of an electrode body constituting the non-aqueous electrolyte secondary battery according to another embodiment;

[0009] Hereinafter, an example of an embodiment of a cylindrical battery according to the present disclosure will be described in detail with reference to the drawings. The embodiment described below is merely an example, and the present disclosure is not limited to the following embodiment. Furthermore, the present disclosure also includes configurations obtained by selectively combining the components of the embodiments described below.

[0010] The configuration of a non-aqueous electrolyte secondary battery 10 will be described with reference to Fig. 1. Fig. 1 is an axial cross-sectional view of the non-aqueous electrolyte secondary battery 10.

[0011] 1 , the nonaqueous electrolyte secondary battery 10 includes an electrode assembly 14, a nonaqueous electrolyte (not shown), and an outer can 16 that houses the electrode assembly 14 and the nonaqueous electrolyte. The outer can 16 is a cylindrical metal container that is open on one axial side and has a bottom, and the opening of the outer can 16 is closed by a sealing body 17. For ease of explanation, the sealing body 17 side of the nonaqueous electrolyte secondary battery 10 will be referred to as the "top" and the bottom side of the outer can 16 will be referred to as the "bottom."

[0012] As will be described in detail later, the electrode body 14 has a positive electrode 11, a negative electrode 12, and a separator 13, and has a wound structure in which the positive electrode 11 and the negative electrode 12 are spirally wound with the separator 13 interposed therebetween. The electrode body 14 has a positive electrode lead 20 connected to the positive electrode 11 by welding or the like.

[0013] Insulating plates 18 and 19 are disposed above and below the electrode body 14, respectively. In the example shown in FIG. 1 , a positive electrode lead 20 passes through a through hole in the insulating plate 18 and extends toward the sealing body 17. The positive electrode lead 20 is connected to the underside of an internal terminal plate 23 of the sealing body 17 by welding or the like, and a cap 27, which is the top plate of the sealing body 17 and is electrically connected to the internal terminal plate 23, serves as the positive electrode terminal. Note that the number of positive electrode leads 20 may be two or more. As will be described in detail later, a negative electrode current collector exposed portion 43 (see FIG. 2 ), where the negative electrode current collector 40 is exposed, is provided at the outermost periphery of the electrode body 14, and the negative electrode current collector exposed portion 43 abuts against the inner surface of the outer can 16. This makes the outer can 16 the negative electrode terminal.

[0014] The non-aqueous electrolyte has lithium ion conductivity and may be a liquid electrolyte (electrolytic solution) or a solid electrolyte.

[0015] The liquid electrolyte (electrolytic solution) contains a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Examples of the non-aqueous solvent include esters, ethers, nitriles, amides, and mixed solvents of two or more of these. Examples of the non-aqueous solvent include ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and mixed solvents of these. The non-aqueous solvent may contain a halogen-substituted compound (e.g., fluoroethylene carbonate) in which at least a portion of the hydrogen atoms of these solvents are substituted with halogen atoms such as fluorine. Examples of the electrolyte salt include LiPF ６ Lithium salts such as

[0016] As the solid electrolyte, for example, a solid or gel-like polymer electrolyte, an inorganic solid electrolyte, etc. can be used. As the inorganic solid electrolyte, a material known in all-solid-state lithium ion secondary batteries, etc. (for example, an oxide-based solid electrolyte, a sulfide-based solid electrolyte, a halogen-based solid electrolyte, etc.) can be used. The polymer electrolyte includes, for example, a lithium salt and a matrix polymer, or a non-aqueous solvent, a lithium salt, and a matrix polymer. As the matrix polymer, for example, a polymer material that absorbs the non-aqueous solvent and gels is used. As the polymer material, for example, a fluororesin, an acrylic resin, a polyether resin, etc. can be used.

[0017] The outer can 16 is a cylindrical metal container with a bottom and an opening on one axial side. A gasket 28 is provided between the outer can 16 and the sealing body 17 to ensure sealing of the battery interior and insulation between the outer can 16 and the sealing body 17. The outer can 16 has a groove 21 formed on its side surface that protrudes inward and supports the sealing body 17. The groove 21 is preferably formed in an annular shape along the circumferential direction of the outer can 16, and supports the sealing body 17 on its top surface. The sealing body 17 is fixed to the top of the outer can 16 by the groove 21 and the open end of the outer can 16 that is crimped to the sealing body 17.

[0018] The sealing body 17 has a structure in which, in order from the electrode body 14 side, an internal terminal plate 23, a lower valve body 24, an insulating member 25, an upper valve body 26, and a cap 27 are stacked. Each member constituting the sealing body 17 has, for example, a disk or ring shape, and each member except for the insulating member 25 is electrically connected to one another. The lower valve body 24 and the upper valve body 26 are connected at their respective centers, and the insulating member 25 is interposed between their respective peripheral edges. If an abnormality occurs in the battery and the internal pressure increases, the lower valve body 24 deforms and breaks, pushing the upper valve body 26 toward the cap 27, thereby interrupting the current path between the lower valve body 24 and the upper valve body 26. If the internal pressure further increases, the upper valve body 26 breaks, and gas is discharged from the opening of the cap 27.

[0019] The configuration of the electrode assembly 14 will be described in detail below with further reference to Figures 2 and 3. Figure 2 is a perspective view of the electrode assembly 14, and Figure 3 is a radial cross-sectional view of the negative electrode 12 near the outermost periphery of the electrode assembly 14. Note that in Figure 3, the radial spacing of the negative electrode 12 is shown larger than it actually is to make the arrangement of the negative electrode 12 and the adhesive layer 50 easier to understand.

[0020] 1 and 2, the electrode assembly 14 has a wound structure in which the positive electrode 11 and the negative electrode 12 are spirally wound with the separator 13 interposed therebetween. In other words, the separator 13 isolates the positive electrode 11 and the negative electrode 12 from each other, and prevents the positive electrode 11 and the negative electrode 12 from coming into contact with each other, thereby preventing a short circuit from occurring.

[0021] The positive electrode 11, negative electrode 12, and separator 13 are all formed in a strip shape and are spirally wound around a winding core arranged along the winding axis, thereby being alternately stacked in the radial direction of the electrode body 14. That is, in the electrode body 14, the longitudinal direction of the positive electrode 11, negative electrode 12, and separator 13 is the winding direction, and the width direction of the positive electrode 11, negative electrode 12, and separator 13 is the axial direction.

[0022] The positive electrode 11 has a positive electrode current collector 30 and a positive electrode mixture layer 31 formed on the positive electrode current collector 30. The positive electrode current collector 30 can be a foil of a metal, such as aluminum or an aluminum alloy, that is stable within the potential range of the positive electrode 11, or a film with such a metal disposed on 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 current collector 30 except for an exposed portion of the positive electrode negative electrode current collector (not shown) to which the positive electrode lead 20 is welded. The positive electrode 11 can be produced, for example, by applying a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, a binder, etc., onto the positive electrode current collector 30, drying the coating, and then compressing it.

[0023] The positive electrode mixture layer 31 contains particulate lithium metal composite oxide as a 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 element constituting the lithium metal composite oxide is, 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, and lithium metal composite oxides containing Ni, Co, and Al.

[0024] Examples of the conductive agent contained in the positive electrode mixture layer 31 include carbon black such as acetylene black and ketjen black, graphite, carbon nanotubes (CNT), carbon nanofibers, graphene, and other carbon materials. Examples of the binder contained in the positive electrode mixture layer 31 include fluorine-containing resins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyimide, acrylic resin, polyolefin, and the like. Furthermore, these resins may be used in combination with carboxymethyl cellulose (CMC) or a salt thereof, polyethylene oxide (PEO), and the like.

[0025] The negative electrode 12 has a negative electrode current collector 40 and a negative electrode mixture layer 41 formed on the negative electrode current collector 40. The negative electrode current collector 40 can be a foil of a metal, such as copper or a copper alloy, that is stable within the potential range of the negative electrode 12, or a film with such a metal disposed on its surface. The thickness of the negative electrode current collector 40 is, for example, 5 μm or more and 50 μm or less. The negative electrode mixture layer 41 contains a negative electrode active material, a binder, and, if necessary, a conductive agent. The negative electrode 12 can be produced by applying a negative electrode mixture slurry containing the negative electrode active material and the binder to the surface of the negative electrode current collector 40, drying the coating, and then compressing it.

[0026] Here, the negative electrode 12 has a negative electrode mixture layer coated portion 42 in which a negative electrode mixture layer 41 is provided on both sides of a negative electrode current collector 40, and a negative electrode current collector exposed portion 43 in which the negative electrode mixture layer 41 is not provided on at least the outer peripheral surface of the negative electrode current collector 40, and the negative electrode current collector 40 is exposed. In this embodiment, the negative electrode mixture layer coated portion 42 is provided over the entire area except for the area in which the negative electrode current collector exposed portion 43 is provided.

[0027] The negative electrode current collector exposed portion 43 is provided on the outermost peripheral surface of the electrode body 14. In this embodiment, the negative electrode current collector exposed portion 43 faces the negative electrode 12. That is, the negative electrode 12 is arranged around the outermost peripheral side of the electrode body 14 over two or more turns. Note that part or all of the negative electrode current collector exposed portion 43 may face the separator 13.

[0028] The negative electrode current collector exposed portion 43 may be provided in a partial region of the outermost periphery of the electrode body 14, but is preferably provided along the entire outermost periphery of the electrode body 14. The negative electrode current collector exposed portion 43 is provided, for example, within a range of a length of approximately one or more and two or less revolutions around the periphery of the electrode body 14 from a winding end 12A, which is one end in the longitudinal direction of the negative electrode 12, located on the outer peripheral surface of the electrode body 14. The negative electrode current collector exposed portion 43 is also arranged so as to abut against the inner surface of the outer can 16.

[0029] In this embodiment, in the negative electrode current collector exposed portion 43, the negative electrode mixture layer 41 is not provided on either side of the negative electrode current collector 40, and both sides of the negative electrode current collector 40 are exposed. By exposing both sides of the negative electrode current collector 40 in the negative electrode current collector exposed portion 43, it becomes easier to form an adhesive layer 50 (described later) on the negative electrode current collector exposed portion 43.

[0030] As shown in FIGS. 2 and 3 , an adhesive layer 50 is provided on the inner circumferential surface of the winding end of the negative electrode current collector exposed portion 43, and the negative electrode current collector exposed portion 43 is adhered to the opposing negative electrode 12 by the adhesive layer 50. In other words, in this embodiment, no member for fixing the winding end 12A of the negative electrode 12, such as tape, is provided on the outermost peripheral surface of the electrode assembly 14; only the negative electrode current collector exposed portion 43 is provided. As a result, even if the diameter of the electrode assembly 14 increases due to the expansion of the negative electrode mixture layer 41 during charging, stress concentration does not occur at the edge of the tape, and damage such as cracking of the electrode plate near the edge of the tape does not occur. For example, the adhesive layer 50 may be formed on the negative electrode current collector exposed portion 43 before spirally winding the negative electrode 12, or may be formed on the negative electrode current collector exposed portion 43 during spiral winding of the negative electrode 12.

[0031] The adhesive layer 50 includes, for example, at least one of a rubber-based polymer, a silicon-based polymer, and an acrylic-based polymer. The rubber-based polymer, the silicon-based polymer, and the acrylic-based polymer have adhesive properties, and therefore can adhere the negative electrode current collector exposed portion 43 to the opposing negative electrode 12.

[0032] The thickness of the adhesive layer 50 is preferably 5.0 μm or less, and more preferably 4.0 μm or less. By reducing the thickness of the adhesive layer 50, the negative electrode current collector exposed portion 43 can be adhered without increasing the outer diameter of the electrode body 14. There are no particular restrictions on the lower limit of the thickness of the adhesive layer 50, but from the viewpoint of workability when attaching the adhesive layer 50 to the negative electrode current collector exposed portion 43, the lower limit is, for example, 0.5 μm.

[0033] The adhesive layer 50 is preferably provided in a region of the inner circumferential surface of the negative electrode current collector exposed portion 43 that includes the winding end 12A of the negative electrode 12. That is, the adhesive layer 50 is preferably provided from the winding end 12A of the negative electrode 12 toward the inside of the winding. This allows the winding end 12A of the negative electrode 12 to be adhered, making it easier to insert the electrode body 14 into the outer can 16 during the battery manufacturing process. Note that the adhesive layer 50 may not be provided at the winding end 12A of the negative electrode 12, but may be provided from a position away from the winding end 12A of the negative electrode 12 toward the inside of the winding. In this case, the winding end 12A of the negative electrode 12 is not adhered.

[0034] The adhesive layer 50 is provided, for example, in a range of length from the winding end 12A of the negative electrode 12 to 0.5 or less of the circumferential length of the electrode assembly 14. In this case, the negative electrode current collector exposed portion 43 can be adhered without increasing the outer diameter of the electrode assembly 14. Furthermore, the adhesive layer 50 is provided, for example, in a range of length from the winding end 12A of the negative electrode 12 to 0.1 or more of the circumferential length of the electrode assembly 14. In this case, the negative electrode current collector exposed portion 43 can be firmly adhered. Therefore, the adhesive layer 50 is provided, for example, in a range of length from the winding end 12A of the negative electrode 12 to 0.1 or more and 0.5 or less of the circumferential length of the electrode assembly 14.

[0035] The adhesive layer 50 is preferably provided across the width direction (short direction) of the negative electrode 12, that is, over the entire region from the top end to the bottom end of the negative electrode current collector 40. In this case, the negative electrode current collector exposed portion 43 can be firmly adhered.

[0036] The negative electrode mixture layer 41 preferably contains a carbon material and a silicon-containing material as the negative electrode active material. The silicon-containing material makes it easier to achieve both high capacity and excellent cycle characteristics. For example, the negative electrode mixture layer 41 may use, as the negative electrode active material, a material containing at least one of an element that alloys with Li, such as Sn, and a material containing the element.

[0037] From the viewpoint of increasing capacity, the content of the silicon-containing material is preferably 5 mass % or more of the total mass of the negative electrode active material, more preferably 8 mass % or more, and even more preferably 10 mass % or more.

[0038] In general, silicon-containing materials undergo a larger volume change during charge and discharge than carbon materials. Therefore, when a silicon-containing material is included as the negative electrode active material, the electrode assembly 14 is more likely to expand radially with repeated charge and discharge. In this embodiment, the winding end 12A of the negative electrode 12 is adhered by an adhesive layer 50 without using tape. This prevents stress concentration due to the tape, and prevents damage to the negative electrode 12, even if the electrode assembly 14 expands radially. In other words, the effects of the present disclosure are more pronounced when the negative electrode mixture layer 41 includes a silicon-containing material as the negative electrode active material.

[0039] The carbon material functioning as the negative electrode active material is, for example, at least one selected from the group consisting of natural graphite, artificial graphite, soft carbon, and hard carbon. Among them, it is preferable to use at least artificial graphite such as massive artificial graphite (MAG) and graphitized mesophase carbon microbeads (MCMB), natural graphite such as flake graphite, massive graphite, and amorphous graphite, or a mixture thereof. The volume-based D50 of the carbon material is, for example, 1 μm or more and 30 μm or less, preferably 5 μm or more and 25 μm or less.

[0040] The silicon-containing material may be any material containing Si, and examples include silicon alloys, silicon compounds, and composite materials containing Si. Among these, composite materials containing Si are preferred. The D50 of composite materials is generally smaller than the D50 of graphite. The volume-based D50 of composite materials is, for example, 1 μm to 15 μm. Note that one type of silicon-containing material may be used alone, or two or more types may be used in combination.

[0041] A suitable silicon-containing material (composite material) is a composite particle including an ion-conducting phase, a Si phase dispersed in the ion-conducting phase, and a conductive layer covering the surface of the ion-conducting phase. The ion-conducting phase is, for example, at least one selected from the group consisting of a silicate phase, an amorphous carbon phase, a silicide phase, and a silicon oxide phase. The Si phase is formed by dispersing Si in the form of fine particles. The ion-conducting phase is a continuous phase composed of a collection of particles finer than the Si phase. The conductive layer is composed of a material with higher conductivity than the ion-conducting phase and forms a good conductive path in the negative electrode mixture layer 41.

[0042] An example of a suitable Si-containing composite material has a sea-island structure in which fine Si is dispersed almost uniformly in an amorphous silicon oxide phase, and the overall structure is represented by the general formula SiO ｘ The silicon oxide may be mainly composed of silicon dioxide. The oxygen to silicon content (x) is, for example, 0.5≦x<2.0, preferably 0.8≦x≦1.5.

[0043] As in the case of the positive electrode mixture layer 31, the binder contained in the negative electrode mixture layer 41 can be a fluorine-containing resin, PAN, polyimide, acrylic resin, polyolefin, or the like, but preferably styrene-butadiene rubber (SBR) is used. The negative electrode mixture layer 41 preferably contains CMC or a salt thereof, polyacrylic acid (PAA) or a salt thereof, polyvinyl alcohol (PVA), or the like. Among these, it is preferable to use SBR in combination with CMC or a salt thereof, PAA or a salt thereof, or the like. The negative electrode mixture layer 41 may contain a conductive agent such as CNT.

[0044] The separator 13 is a porous sheet having ion permeability and insulating properties. Specific examples of the porous sheet include a microporous thin film, a woven fabric, and a nonwoven fabric. Suitable materials for the separator 13 include polyolefins such as polyethylene and polypropylene, and cellulose. The separator 13 may have a single-layer structure or a multi-layer structure. A highly heat-resistant resin layer such as an 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.

[0045] The above-described embodiment can be modified as appropriate without impairing the object of the present disclosure. For example, in the above-described embodiment, the electrode body 14 does not have a negative electrode lead, but the electrode body 14 may have a negative electrode lead. For example, a negative electrode current collector exposed portion 43 may be provided at the winding start side of the negative electrode 12, and a negative electrode lead may be welded to the negative electrode current collector exposed portion 43.

[0046] 4 , the negative electrode 12 may have a slit 51 extending along the width direction of the negative electrode 12, on a wound inner side of the adhesive layer 50. In the manufacturing process of the nonaqueous electrolyte secondary battery 10, for example, the inside of the outer can 16 may be pressurized in order to relieve stress inside the electrode assembly 14. At this time, the stress inside the electrode assembly 14 may be relieved by cutting the slit 51. The slit 51 may be a slit that penetrates the negative electrode 12 in the thickness direction, or a slit that does not penetrate the negative electrode 12 in the thickness direction. The slit 51 may be provided across the entire width direction of the negative electrode 12, or may be provided only in a portion of the width direction of the negative electrode 12.

[0047] Here, an example of a method for manufacturing a nonaqueous electrolyte secondary battery 10 will be described, in which the negative electrode 12 has a slit 51 and the slit 51 is finally cut. The method for manufacturing the nonaqueous electrolyte secondary battery 10 includes, for example, an adhesive layer forming step of forming an adhesive layer 50, a slit forming step of forming the slit 51 in the negative electrode 12, an electrode body forming step of forming a wound electrode body 14, and a cutting step of inserting the electrode body 14 into the outer can 16 and then cutting the slit 51. The adhesive layer forming step and the slit forming step may be performed before the electrode body forming step or during the electrode body forming step. The slit forming step may also be performed before the adhesive layer forming step or after the adhesive layer forming step.

[0048] In the adhesive layer forming step, the adhesive layer 50 is applied to the inner circumferential surface of the negative electrode current collector exposed portion 43, for example, within a predetermined length from the winding end 12A of the negative electrode 12. The method for applying the adhesive layer 50 is not particularly limited, and examples include methods using a roll coater, reverse roll coater, transfer roll coater, gravure coater, gravure reverse coater, comma coater, rod coater, blade coater, bar coater, wire bar coater, die coater, lip coater, dip coater, or the like.

[0049] In the slit forming step, slits 51 are formed at a position on the inner side of the adhesive layer 50. The method for forming slits 51 is not particularly limited, and examples include methods using a known perforation machine or slitting machine. The slits 51 may be formed at any position on the inner side of the adhesive layer 50, but are preferably formed in a range of 1 mm to 30 mm from the winding start end 50A of the adhesive layer 50 (see FIG. 4) along the longitudinal direction of the negative electrode 12. The shape, size, etc. of slits 51 are not particularly limited as long as they can be cut in the cutting step described below.

[0050] In the electrode body formation process, a strip-shaped positive electrode 11 and a strip-shaped negative electrode 12 are wound with a separator 13 interposed therebetween to form an electrode body 14. After forming the electrode body 14, the portion where the adhesive layer 50 is formed is pressed from the radially outer side, so that the winding end 12A of the negative electrode 12 can be adhered by the adhesive layer 50.

[0051] In the cutting process, the electrode assembly 14, in which the winding end 12A of the negative electrode 12 produced in the electrode assembly forming process is adhered by the adhesive layer 50, is inserted into an outer can 16. Then, an external load is applied to cut the slit 51. This causes the electrode assembly 14 to expand radially outward, thereby alleviating stress inside the electrode assembly 14. Furthermore, when the electrode assembly 14 expands radially outward, the negative electrode current collector exposed portion 43, which is the outermost surface of the electrode assembly 14, abuts against the inner surface of the outer can 16.

[0052] An example of a method for cutting the slit 51 is to apply pressure to the inside of the outer can 16. By applying pressure to the inside of the outer can 16, a force is applied to the electrode body 14 in the radially outward direction. At this time, a load is also applied to the slit 51, which allows the slit 51 to be cut. Note that the method for cutting the slit 51 is not limited to this. For example, the electrode body 14, to which the negative electrode current collector exposed portion 43 is adhered by the adhesive layer 50, may be inserted into the outer can 16, and then tension may be applied to the negative electrode 12 to cut the slit 51.

[0053] The present disclosure is further described by the following embodiments. Aspect 1: A non-aqueous electrolyte secondary battery comprising: an electrode assembly in which a strip-shaped positive electrode and a strip-shaped negative electrode are wound with a separator interposed therebetween; and a bottomed cylindrical outer can housing the electrode assembly, wherein the negative electrode has a negative electrode current collector exposed portion where the negative electrode current collector is exposed and no negative electrode mixture layer is provided on at least the outer peripheral surface of the negative electrode current collector, the negative electrode current collector exposed portion is provided on the outermost periphery of the electrode assembly, and an adhesive layer is provided on at least a portion of the inner peripheral surface of the negative electrode current collector exposed portion, and the negative electrode current collector exposed portion is adhered by the adhesive layer to the negative electrode facing the negative electrode current collector exposed portion. Aspect 2: The non-aqueous electrolyte secondary battery according to Aspect 1, wherein the adhesive layer is provided in a range of a length of 0.5 or less of the circumference of the electrode assembly from the winding termination end of the negative electrode. Configuration 3: The nonaqueous electrolyte secondary battery according to Configuration 1 or 2, wherein the adhesive layer has a thickness of 5.0 μm or less.Configuration 4: The nonaqueous electrolyte secondary battery according to any one of Configurations 1 to 3, wherein the adhesive layer is provided across the width direction of the negative electrode.Configuration 5: The nonaqueous electrolyte secondary battery according to any one of Configurations 1 to 4, wherein only the negative electrode current collector exposed portion is provided on the outermost peripheral surface of the electrode assembly.Configuration 6: The nonaqueous electrolyte secondary battery according to any one of Configurations 1 to 5, wherein the negative electrode mixture layer contains a silicon-containing material as a negative electrode active material.Configuration 7: The nonaqueous electrolyte secondary battery according to any one of Configurations 1 to 6, wherein the negative electrode has a slit extending along the width direction of the negative electrode, on a wound inner side than the adhesive layer. Configuration 8: A method for manufacturing a nonaqueous electrolyte secondary battery, comprising: an electrode body forming step of winding a strip-shaped positive electrode and a strip-shaped negative electrode with a separator interposed therebetween to form an electrode body; an adhesive layer forming step of forming an adhesive layer on an inner peripheral surface of a negative electrode current collector exposed portion where a negative electrode mixture layer is not provided on at least an outer peripheral surface of a negative electrode current collector; a slit forming step of forming a slit in the negative electrode, on a wound inner side than the adhesive layer, extending along the width direction of the negative electrode; and a cutting step of inserting the electrode body, with the negative electrode current collector exposed portion bonded by the adhesive layer, into a bottomed cylindrical outer can, and then cutting the slit.Configuration 9: The method for manufacturing a nonaqueous electrolyte secondary battery according to Configuration 8, wherein the cut is cut by applying pressure to the inside of the outer can.

[0054] REFERENCE SIGNS LIST 10 non-aqueous electrolyte secondary battery, 11 positive electrode, 12 negative electrode, 12A winding end, 13 separator, 14 electrode body, 16 outer can, 17 sealing body, 18, 19 insulating plate, 20 positive electrode lead, 21 grooved portion, 23 internal terminal plate, 24 lower valve body, 25 insulating member, 26 upper valve body, 27 cap, 28 gasket, 30 positive electrode current collector, 31 positive electrode mixture layer, 40 negative electrode current collector, 41 negative electrode mixture layer, 42 negative electrode mixture layer coated portion, 43 negative electrode current collector exposed portion, 50 adhesive layer, 50A winding start end, 51 cut

Claims

1. A non-aqueous electrolyte secondary battery comprising: an electrode body in which a strip-shaped positive electrode and a strip-shaped negative electrode are wound with a separator interposed therebetween; and a bottomed cylindrical outer can that houses the electrode body, wherein the negative electrode has a negative electrode current collector exposed portion where the negative electrode current collector is exposed without a negative electrode mixture layer provided on at least the outer peripheral surface of the negative electrode current collector, the negative electrode current collector exposed portion is provided on the outermost periphery of the electrode body, an adhesive layer is provided on at least a part of the inner peripheral surface of the negative electrode current collector exposed portion, and the negative electrode current collector exposed portion is adhered to the negative electrode facing the negative electrode current collector exposed portion by the adhesive layer.

2. The non-aqueous electrolyte secondary battery according to claim 1, wherein the adhesive layer is provided in a range of a length of 0.5 turns or less of the circumference of the electrode body from the end of winding of the negative electrode.

3. The non-aqueous electrolyte secondary battery according to claim 1, wherein the thickness of the adhesive layer is 5.0 μm or less.

4. The non-aqueous electrolyte secondary battery according to claim 1, wherein the adhesive layer is provided across the width direction of the negative electrode.

5. The non-aqueous electrolyte secondary battery according to claim 1, wherein only the negative electrode current collector exposed portion is provided on the outermost peripheral surface of the electrode body.

6. The non-aqueous electrolyte secondary battery according to claim 1, wherein the negative electrode mixture layer contains a silicon-containing material as a negative electrode active material.

7. The non-aqueous electrolyte secondary battery according to claim 1, wherein a cut extending along the width direction of the negative electrode is provided on the inner side of the winding of the negative electrode with respect to the adhesive layer.

8. A method for manufacturing a non-aqueous electrolyte secondary battery, comprising: an electrode body forming step of winding a strip-shaped positive electrode and a strip-shaped negative electrode with a separator interposed therebetween to form an electrode body; an adhesive layer forming step of forming an adhesive layer on the inner peripheral surface of a negative electrode current collector exposed portion where the negative electrode mixture layer is not provided on at least the outer peripheral surface of the negative electrode current collector; a cut forming step of forming a cut extending along the width direction of the negative electrode on the inner side of the winding of the negative electrode with respect to the adhesive layer; and a cutting step of cutting the cut after inserting the electrode body to which the negative electrode current collector exposed portion is adhered by the adhesive layer into a bottomed cylindrical outer can.

9. The method for manufacturing a non-aqueous electrolyte secondary battery according to claim 8, wherein the cut is cut by pressurizing the inside of the outer can.

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