Non-aqueous electrolyte secondary battery

Abstract

This non-aqueous electrolyte secondary battery includes: a wound electrode body (14) having a positive electrode and a negative electrode (12); and at least one tape (40, 41) affixed to the outermost peripheral surface of the electrode body (14). A negative electrode core body (35) of the negative electrode is positioned on the outermost peripheral surface of the electrode body (14), and the negative electrode core body (35) is in contact with the inner peripheral surface of a case body. The tape (40, 41) has an overall rectangular shape in a state of being extended along a plane, and at least one end edge (42) thereof has a non-linear shape.

Description

Non-aqueous electrolyte secondary battery

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

[0002] Conventionally, a non-aqueous electrolyte secondary battery including an electrode body in which a positive electrode and a negative electrode are wound through a separator, and a bottomed cylindrical case body that houses the electrode body and an electrolytic solution has been known. In this secondary battery, a tape is adhered to the outermost peripheral surface of the electrode body to fix the electrode body (see Patent Documents 1 and 2). Further, in a non-aqueous electrolyte secondary battery, by exposing the negative electrode core of the negative electrode on the outermost peripheral surface of the electrode body and bringing the negative electrode core into contact with the case body, the heat dissipation of the battery is improved, and it is known that the heat generation of the battery during an external short circuit is suppressed (see Patent Document 3).

[0003] JP-A-9-161814 JP-A-2009-199974 WO 2009 / 144919

[0004] By the way, when the electrode body expands with the charge / discharge cycle of the non-aqueous electrolyte secondary battery, the linear pressure applied from the edge of the tape to the negative electrode core increases. As a result, there is a possibility that damage such as cracks occurs in the negative electrode core. Since the damage of the negative electrode core causes a decrease in the performance of the battery, suppressing the damage of the negative electrode core is an important issue.

[0005] An object of the present disclosure is to suppress damage to a negative electrode core in a non-aqueous electrolyte secondary battery having a configuration in which the negative electrode core on the outermost peripheral surface of the electrode body contacts the case body and a tape is adhered to the outermost peripheral surface of the electrode body.

[0006] The non-aqueous electrolyte secondary battery according to the present disclosure includes a bottomed cylindrical case body, a wound electrode body housed in the case body in which a positive electrode and a negative electrode are wound through a separator, and at least one tape adhered to the outermost peripheral surface of the electrode body so as to fix the end of the wound electrode body. The negative electrode core constituting the negative electrode is located on the outermost peripheral surface of the electrode body and contacts the inner peripheral surface of the case body. The tape is entirely rectangular in a state of being extended along a plane, and at least one edge is non-linear, and is a non-aqueous electrolyte secondary battery.

[0007] According to the non-aqueous electrolyte secondary battery described herein, even if the electrode body expands during charging and discharging, the linear pressure applied to the negative electrode core from the tape attached to the outermost surface of the electrode body can be reduced. This suppresses damage to the negative electrode core.

[0008] This is a cross-sectional view of a non-aqueous electrolyte secondary battery according to an embodiment. This is a perspective view of the electrode body of a non-aqueous electrolyte secondary battery according to an embodiment. This is a cross-sectional view perpendicular to the winding axis direction of the outer portion of the electrode body in the embodiment. This is an enlarged view showing each tape in Figure 2 stretched along a plane. This is a perspective view of the electrode body of a comparative example of a non-aqueous electrolyte secondary battery. This is an enlarged view showing the longitudinal middle portion of a tape constituting another example of a non-aqueous electrolyte secondary battery stretched along a plane. This is a perspective view of the electrode body of another example of a non-aqueous electrolyte secondary battery according to an embodiment. This is an enlarged view of the longitudinal middle portion of a tape used in another example of a non-aqueous electrolyte secondary battery according to an embodiment. This figure shows a tape used in another example of a non-aqueous electrolyte secondary battery stretched along a plane.

[0009] Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the following description, specific shapes, materials, numerical values, directions, etc., are examples to facilitate understanding of the present invention and can be appropriately modified to suit the specifications of the non-aqueous electrolyte secondary battery. Furthermore, the term "abbreviated" below is used to include, for example, cases where they are exactly the same, as well as cases where they can be considered substantially the same. Moreover, when multiple embodiments and modifications are included below, it is intended from the outset that their characteristic parts may be appropriately combined and used.

[0010] Figure 1 is a cross-sectional view of a non-aqueous electrolyte secondary battery 10 according to an embodiment. Figure 2 is a perspective view of the electrode body 14 of the non-aqueous electrolyte secondary battery 10. Figure 3 is a cross-sectional view perpendicular to the winding axis direction of the outer portion of the electrode body 14 in the embodiment. Figure 4 is an enlarged view showing the state in which each tape 40, 41 of Figure 2 is extended along a plane. As illustrated in Figures 1 to 4, the non-aqueous electrolyte secondary battery 10 comprises a wound electrode body 14, a first tape 40 and a second tape 41 (Figures 2 to 4) attached to the outermost surface of the electrode body 14, a non-aqueous electrolyte (not shown), a case body 15 and a sealing body 16. The wound 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 spirally via the separator 13. Hereinafter, one side of the electrode body 14 in the winding axis direction may be referred to as "upper" and the other side in the winding axis direction as "lower".

[0011] The non-aqueous electrolyte has ionic conductivity (e.g., lithium ion conductivity). The non-aqueous electrolyte comprises a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. The non-aqueous electrolyte is not limited to a liquid electrolyte (non-aqueous electrolyte solution), but may also be a solid electrolyte using a gel-like polymer or the like. The non-aqueous electrolyte secondary battery 10 is preferably a lithium-ion battery. The electrolyte salt may be, for example, LiBF ４ LiPF ６ Lithium salts such as the above are used. Non-aqueous solvents include, for example, esters such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and methyl propionate (MP), as well as ethers, nitriles, amides, and mixed solvents of two or more of these. The non-aqueous solvent may contain halogen-substituted products in which at least some of the hydrogen atoms of these solvents are replaced with halogen atoms such as fluorine.

[0012] Examples of halogen-substituted compounds include fluorinated cyclic carbonates such as fluoroethylene carbonate (FEC), fluorinated linear carbonates, and fluorinated linear carboxylic acid esters such as methyl fluoropropionate (FMP). In terms of suppressing the deterioration of the charge-discharge cycle characteristics of non-aqueous electrolyte secondary batteries or improving the input characteristics, the non-aqueous electrolyte preferably contains 5% by mass or more of FEC relative to the mass of the non-aqueous electrolyte, and more preferably contains 5% to 15% by mass of FEC.

[0013] As solid electrolytes, for example, solid or gel-like polymer electrolytes, inorganic solid electrolytes, etc., are used. Polymer electrolytes include, for example, a lithium salt and a matrix polymer, or a non-aqueous solvent, a lithium salt and a matrix polymer. As matrix polymers, for example, polymer materials that absorb non-aqueous solvents and gel are used. As polymer materials, for example, fluororesins, acrylic resins, polyether resins, etc., are used. As inorganic solid electrolytes, for example, materials known for all-solid-state lithium-ion secondary batteries, etc. (for example, oxide-based solid electrolytes, sulfide-based solid electrolytes, halide-based solid electrolytes, etc.) are used.

[0014] The positive electrode 11 has a strip-shaped positive electrode core and positive electrode mixture layers formed on the inner surface (radial inner surface) and outer surface (radial outer surface) of the winding of the positive electrode core, respectively. The positive electrode 11 is provided with a plain section (not shown) where the positive electrode core is exposed, and a positive electrode lead 19 (Figures 1 and 2) is joined to the plain section, for example, by ultrasonic welding. For the positive electrode core, a metal foil such as aluminum, or a film with the metal arranged on its surface, can be used. A preferred positive electrode core is a metal foil mainly composed of aluminum or an aluminum alloy. The thickness of the positive electrode core is, for example, 10 μm to 30 μm. The positive electrode lead 19 is a conductive member for electrically connecting the positive electrode core and the positive electrode terminal, and extends from the positive electrode core to one side (upwards) in the winding axis direction α of the electrode body 14. The positive electrode lead 19 is provided, for example, approximately in the center of the radial direction β of the electrode body 14. The positive electrode lead 19 is a strip-shaped conductive member. The constituent material of the positive electrode lead is not particularly limited. Preferably, the positive electrode lead 19 is made of a metal mainly composed of aluminum.

[0015] The positive electrode mixture layer preferably contains a positive electrode active material, a conductive agent, and a binder. The positive electrode 11 is manufactured by applying 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) to both sides of the positive electrode core, followed by drying and rolling.

[0016] Examples of positive electrode active materials include lithium-containing transition metal oxides containing transition metal elements such as Co, Mn, and Ni. While lithium-containing transition metal oxides are not particularly limited, they generally have the formula Li １＋ｘ MO ２ It is preferable that the composite oxide is represented by the formula (wherein -0.2 < x ≤ 0.2, and M includes at least one of Ni, Co, Mn, and Al).

[0017] Examples of the conductive agents mentioned above include carbon materials such as carbon black (CB), acetylene black (AB), Ketjenblack, and graphite. Examples of the binders mentioned above include fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyimide (PI), acrylic resins, and polyolefin resins. These resins may also be used in combination with carboxymethylcellulose (CMC) or its salts, polyethylene oxide (PEO), etc. These may be used individually or in combination of two or more types.

[0018] The negative electrode 12 has a strip-shaped negative electrode core 35 and negative electrode mixture layers formed on the inner surface (radial inner surface) and outer surface (radial outer surface) of the winding of the negative electrode core 35, respectively. The negative electrode core 35 on the outermost surface of the electrode body 14 contacts the inner surface of the cylindrical portion of the case body 15, which will be described later as the negative electrode terminal, thereby electrically connecting the negative electrode 12 to the case body 15. For this reason, the negative electrode core 35 is located along the entire circumferential direction of the outermost surface of the electrode body 14, and the negative electrode core 35 is in contact with the case body 15. The negative electrode core 35 may be configured to be exposed only on a part of the circumferential direction of the outermost surface of the electrode body. For example, the negative electrode core 35 can be made of a metal foil such as copper, or a film with the metal arranged on its surface. The thickness of the negative electrode core 35 is, for example, 5 μm to 30 μm.

[0019] Furthermore, a negative electrode lead (not shown) can be connected to the negative electrode core while the negative electrode core exposed on the outermost surface of the electrode body 14 is in contact with the inner surface of the cylindrical portion of the case body 15. In this case, the portion of the negative electrode lead extending downward from the negative electrode core is electrically connected to the bottom plate of the case body 15. The negative electrode lead is a strip-shaped conductive member. The constituent material of the negative electrode lead is not particularly limited. Preferably, the negative electrode lead is made of a metal mainly composed of nickel or copper, or a metal containing both nickel and copper.

[0020] The negative electrode mixture layer preferably contains a negative electrode active material and a binder. The negative electrode 12 is manufactured by, for example, applying a negative electrode mixture slurry containing a negative electrode active material, a binder, and water to both sides of the negative electrode core 35, and then drying and rolling it.

[0021] The negative electrode active material is not particularly limited as long as it can reversibly intercept 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 and composite oxides containing these can be used. The binder contained in the negative electrode mixture layer is, for example, the same resin as in the case of the positive electrode 11. When preparing the negative electrode mixture slurry with an aqueous solvent, styrene-butadiene rubber (SBR), CMC or its salts, polyacrylic acid or its salts, polyvinyl alcohol, etc. can be used. These may be used individually or in combination of two or more.

[0022] A porous sheet having ion permeability and insulating properties is used for the separator 13 (Figures 1 and 3). Specific examples of porous sheets include microporous thin films, woven fabrics, and nonwoven fabrics. The material of the separator 13 is preferably an olefin resin such as polyethylene or polypropylene. The thickness of the separator 13 is, for example, 10 μm to 50 μm. The separator 13 is becoming thinner as batteries increase in capacity and power. The separator 13 has a melting point of, for example, 130°C to 180°C.

[0023] As described above, the electrode body 14 has a wound structure in which a positive electrode 11 and a negative electrode 12 are wound in a spiral shape via a separator 13. The positive electrode 11, the negative electrode 12, and the separator 13 are all formed in a strip shape and are wound in a spiral shape around the winding core so that they are alternately stacked in the radial direction β of the electrode body 14. A space 28 is formed in the winding core. In the electrode body 14, the longitudinal direction of each electrode plate is the winding direction γ (Figures 2 and 3), and the width direction of each electrode plate is the winding axis direction α (Figures 1 and 2).

[0024] As shown in Figures 2 to 4, the first tape 40 and the second tape 41 are winding stop tapes that are attached to the outermost surface of the electrode body 14 along the winding direction γ so as to fix the winding end E of the electrode body 14 to the outermost surface of the electrode body 14. The first tape 40 is attached to the first end side of the electrode body 14 in the winding axis direction α (upper end in Figure 2). The second tape 41 is attached to the second end side of the electrode body 14 in the winding axis direction α (lower end in Figure 2). Each tape 40, 41 is attached to the outermost surface of the electrode body 14 so as to straddle the winding end E (Figure 3) of the electrode body 14 in the winding direction. In this embodiment, the winding end of the negative electrode core 35 is the winding end E of the electrode body 14. However, the winding end of the negative electrode 12 may be pulled out in the winding direction γ from the inside of the winding end of the negative electrode 12, as long as it does not hinder contact between the case body 15 and the outermost surface of the electrode body 14 of the negative electrode core 35.

[0025] The case body 15 and the sealing body 16 constitute a metal battery case that houses the electrode body 14 and the non-aqueous electrolyte. Insulating plates 17 and 18 are provided above and below the electrode body 14, respectively. The positive electrode lead 19 extends towards the sealing body 16 through a through hole in the upper insulating plate 17 and is welded to the lower surface of the internal terminal plate 22, which is the bottom plate of the sealing body 16. In the non-aqueous electrolyte secondary battery 10, the cap 26, which is the top plate of the sealing body 16 and is electrically connected to the internal terminal plate 22, becomes the positive electrode terminal.

[0026] The case body 15 is a bottomed cylindrical metal container with an opening, for example, a bottomed cylindrical shape. A gasket 27 is provided between the case body 15 and the sealing body 16 to ensure airtightness inside the battery case. The case body 15 has a protruding portion 21 that supports the sealing body 16, which is formed, for example, by pressing the side portion from the outside. The protruding portion 21 is preferably formed in an annular shape along the circumferential direction of the case body 15, and its upper surface supports the sealing body 16. The sealing body 16 seals the opening of the case body 15.

[0027] The sealing body 16 has an internal terminal plate 22, a lower valve body 23, an insulating member 24, an upper valve body 25, and a cap 26, which 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 lower valve body 23 and the upper valve body 25 are connected to each other at their respective centers, with the insulating member 24 interposed between their respective peripheral edges. When the internal pressure of the battery rises due to abnormal heat generation and reaches a predetermined value, for example, the lower valve body 23 ruptures, and the upper valve body 25 bulges towards the cap 26 and separates from the lower valve body 23, thereby interrupting the current path between them. If the internal pressure rises further and reaches a predetermined value, the upper valve body 25 ruptures, and gas is discharged from the opening 26a of the cap 26.

[0028] The electrode body 14, the first tape 40, and the second tape 41 will be described in detail below with reference to Figures 2 to 4. In the electrode body 14, the longitudinal length corresponding to the winding direction γ of the negative electrode 12 is greater than the longitudinal length of the positive electrode 11 (Figure 5). As a result, in the electrode body 14, at least the portion of the positive electrode 11 where the positive electrode mixture layer is formed is positioned opposite the portion of the negative electrode 12 where the negative electrode mixture layer is formed, via the separator 13.

[0029] As shown in Figure 3, the negative electrode 12 includes a single-sided compound layer region 12a indicated by a line of intermediate thickness, a double-sided compound layer region 12b indicated by a line thicker than the intermediate thickness, and a blank region 12c indicated by a line thinner than the intermediate thickness. In the double-sided compound layer region 12b, negative electrode compound layers are formed on both the outer and inner sides of the negative electrode core 35. In the single-sided compound layer region 12a, the negative electrode compound layer is formed only on the inner side of the negative electrode core 35, which is the core side of the winding. In the blank region 12c, no negative electrode compound layer is formed on either the outer or inner side of the negative electrode core 35. In Figure 4, the dashed lines show two separators 13.

[0030] As shown in Figures 2 and 3, the first tape 40 and the second tape 41 are attached to both ends of the outermost surface of the electrode body 14 in the winding axis direction α, so as to fix the winding end E of the electrode body 14, which is the winding end of the negative electrode 12, to the outermost surface of the electrode body 14 where the negative electrode core 35 is exposed. Each tape 40 and 41 includes a base layer and an adhesive layer disposed on the inner surface of the base layer. Each tape 40 and 41 is made of an insulating material such as PP tape. PP tape has an adhesive layer formed on one side (inner surface) of a base layer made of porous or non-porous polypropylene (PP). The base layer of each tape 40 and 41 can be appropriately selected from viewpoints such as strength, resistance to electrolyte, processability, and cost, and is not limited to polypropylene; polyimide (PI), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), etc., can also be used. Furthermore, the base layer can also have a laminated structure. For example, a heat-resistant layer in which inorganic particles such as metal oxides are dispersed in an organic material can be used as part of the base layer. The adhesive layer of each tape 40, 41 is made of a resin that is adhesive at room temperature, and is made of, for example, an acrylic resin or a rubber resin.

[0031] As shown in Figure 4, each tape 40, 41 is rectangular in shape when stretched along a plane. Rectangular in shape means that the edges of each tape 40, 41 are composed of four linear edges. As shown in Figure 2, the first tape 40 and the second tape 41 are attached to both ends of the electrode body 14 in the winding axis direction α, respectively, along the winding direction γ. The edges 42 located at both ends of each tape 40, 41 in the winding axis direction α are wavy. Specifically, as shown in Figures 2 and 4, each tape 40, 41 has a pair of edges 42 located at both ends in the winding axis direction α and a pair of edges 43 located at both ends in the winding direction γ. Each tape 40, 41 has a length in the winding direction γ that is greater than the length in the winding axis direction α.

[0032] Each end edge 43 of each tape 40, 41 is a straight line along the winding axis α. On the other hand, each end edge 42 of each tape 40, 41 is corrugated, with the peaks and valleys having a curved shape with a circular arc cross-section. As a result, each end edge 42 of each tape 40, 41 is non-linear. Therefore, the length of each end edge 42 is longer than if it were a straight edge along the longitudinal direction of each tape when extended along a plane. Consequently, as will be described later, when the electrode body 14 expands during charging and discharging, the linear pressure applied to the negative electrode core body 35 from each end edge 42 of each tape 40, 41 can be reduced, thereby suppressing damage such as cracks in the negative electrode core body 35.

[0033] In this embodiment, with the tapes 40 and 41 stretched along a plane, it is preferable that the length of each edge 42 is 1.2 to 2.0 times longer than the length of each edge 42 in the comparative example shown in Figure 5, which will be described later. If the length of each edge 42 is less than 1.2 times the length of the comparative example, the effect of reducing the linear pressure applied to the negative electrode core 35 will be reduced. On the other hand, if the length of each edge 42 is 2.0 times or more the length of the comparative example, when each edge 42 is wavy, the amplitude of the waveform becomes larger than the wavelength, the shape of the peaks and valleys becomes narrower towards the tip and sharp corners occur, and stress concentration is likely to occur in the negative electrode core 35 pressed against each edge 42. If this stress concentration becomes significant, it can cause damage to the negative electrode core 35, which is undesirable.

[0034] In the non-aqueous electrolyte secondary battery 10 described above, since the edges 42 of the tapes 40 and 41 are non-linear when unfolded, the linear pressure applied to the negative electrode core 35 from the edges 42 of each tape 40 and 41 can be reduced when the electrode body 14 expands during charging and discharging. This suppresses damage such as cracks in the negative electrode core 35.

[0035] Furthermore, of the edges 42 of each tape 40, 41, only one edge 42 may be waveformd. For example, since the electrode body 14 is most likely to bulge in the center of the winding axis direction α, linear pressure is easily applied from the edge 42 of each tape 40, 41 that is closer to the center of the winding axis direction α to the outermost negative electrode core body 35 of the electrode body 14. For this reason, of the edges 42 of each tape 40, 41, only one edge 42 that is closer to the center of the winding axis direction α may be waveformd.

[0036] Furthermore, in this example, each edge 42 of each tape 40, 41 has a waveform with a circular arc cross-section at the peaks and valleys. This appropriately regulates the relationship between the amplitude and wavelength of the waveform, preventing the sharp corners of each edge 42 from being pressed against the outermost surface of the negative electrode core 35 when the electrode body 14 expands during charging and discharging. Therefore, excessive stress concentration on this outermost surface can be suppressed, further reducing damage to the negative electrode core 35. In addition, in each tape 40, 41, the edges 43 at both ends in the winding direction γ can also be made waveformd along with the edges 42.

[0037] Figure 5 is a perspective view of the electrode body 14a of a comparative example non-aqueous electrolyte secondary battery. In the comparative example electrode body 14a, the edges 42a located at both ends of the tapes 40a and 41a attached to both ends of the electrode body 14a in the winding axis direction α are simply straight lines extending along the longitudinal direction of the tapes 40a and 41a when extended along a plane. In such a comparative example, when the electrode body 14a expands during charging and discharging, the linear pressure applied to the negative electrode core body 35 from the edges 42a of each tape 40a and 41a is greater than in the embodiment, which may cause damage such as cracks in the negative electrode core body 35.

[0038] Figure 6 is an enlarged view showing the longitudinal middle portion of tapes 40b and 41b, which constitute a non-aqueous electrolyte secondary battery in another embodiment, when extended along a plane. As shown in Figure 6, the tapes 40b and 41b used in this example have edges 42b at both ends in the winding axis direction α (see Figure 2) that are corrugated in a zigzag pattern of straight lines. In this alternative configuration as well, since the edges 42b of tapes 40b and 41b are non-linear when unfolded, damage to the negative electrode core can be suppressed when the electrode body expands during charging and discharging. Furthermore, from the perspective of suppressing excessive stress concentration on the outermost surface of the negative electrode core from the tape when the electrode body expands, it is preferable to use a configuration in which the corrugation of the edges 42 is curved, as in the tapes 40 and 41 shown in Figures 1 to 4. In this example, the other configurations and operations are the same as those in Figures 1 to 4.

[0039] Figure 7 is a perspective view of the electrode body 14c of a non-aqueous electrolyte secondary battery in another embodiment. Figure 8 is an enlarged view of the longitudinal middle portion of the tape 50 used in a non-aqueous electrolyte secondary battery in another embodiment.

[0040] In this example, the tape 50 is attached to the outermost surface of the electrode body 14 along the winding axis α so as to fix the end E of the winding end of the electrode body 14 to the outermost surface of the electrode body 14. The length of the tape 50 in the winding axis α is greater than the length Wa in the winding direction γ. The length α of the tape 50 in the winding axis can be, for example, 1 / 2 or more of the total length of the electrode body 14 in the winding axis. The length Wa of the tape 50 in the winding direction γ can be, for example, 5% or more and 50% or less of the circumference of the outermost surface of the electrode body 14.

[0041] The tape 50 is long along the winding axis direction α and is rectangular as a whole in a state extended along a plane. The edge portions 51 at both ends in the winding direction γ of the tape 50 are non-linear in a wave form, similar to the respective edge portions 42 of the tapes 40 and 41 with the configurations shown in FIGS. 1 to 4. When the tape 50 is long in the winding axis direction α in this way, when the electrode body 14 expands, the influence when a linear pressure is applied from the tape 50 to the outermost negative electrode core 35 of the electrode body 14 is greater at the edge portions 51 at both ends in the winding direction γ than at the edge portions 52 at both ends in the winding axis direction α. Therefore, in the configuration of this example, the edge portions 51 at both ends in the winding direction γ of the tape 50 are non-linear in a wave form. Thereby, when the electrode body 14 expands due to charge and discharge, damage to the negative electrode core 35 can be suppressed. In each tape 50, the edge portions 52 at both ends in the winding axis direction α may also be in a wave form together with the respective edge portions 51. Also, only one of the edge portions 51 of each tape 50 may be in a wave form. In this example, other configurations and operations are the same as those of the configurations shown in FIGS. 1 to 4.

[0042] FIG. 9 is a diagram showing a state where the tapes 40d and 41d used in a non-aqueous electrolyte secondary battery according to another example of the embodiment are extended along a plane. The tapes 40d and 41d used in the configuration of this example have a pair of edge portions 42d located at both ends in the winding axis direction of the electrode body and a pair of edge portions 43d located at both ends in the winding direction, and are rectangular as a whole in a state extended along a plane. Each of the tapes 40 and 41 has a greater length in the winding direction than in the winding axis direction.

[0043] Each end edge 43d of each tape 40d and 41d is linear along the winding axis. On the other hand, each end edge 42d of each tape 40d and 41d is curved with a circular arc cross-section that protrudes outward. As a result, each end edge 42d of each tape 40d and 41d is nonlinear. The tape is attached to the outermost surface along the winding direction to fix the end of the winding of the electrode body, similar to the configuration in Figures 1 to 4. In this example using such tape, as in the configuration in Figures 1 to 4, each end edge 42d of the tape 40d and 41d is nonlinear when unfolded, so that when the electrode body 14 expands during charging and discharging, the linear pressure applied from each end edge 42d to the outermost negative electrode core of the electrode body can be reduced. This suppresses damage to the negative electrode core. In this example, the other configurations and operations are the same as in the configuration in Figures 1 to 4. In addition, the tape used in this example can also be attached to the outermost surface of the electrode body so that the longitudinal direction of the tape is aligned with the winding axis direction of the electrode body, similar to the configuration in Figures 7 and 8.

[0044] Furthermore, in the configuration of this disclosure, if at least one edge of the tape attached to the outermost surface of the electrode body is non-linear, the non-linear shape is not limited to the waveform or arc shape of each example above, but can also be other non-linear shapes such as a shape consisting of multiple straight lines oriented in different directions, a shape consisting of multiple curves, or a shape that combines straight lines and curves.

[0045] Furthermore, in each of the above examples, the tape is not limited to being attached along the winding direction or winding axis direction on the outermost surface of the electrode body, but may also be attached in a direction inclined with respect to the winding direction, for example.

[0046] 10 Non-aqueous electrolyte secondary battery, 11 Positive electrode, 12 Negative electrode, 12a Single-sided compound layer region, 12b Double-sided compound layer region, 12c Plain region, 13 Separator, 14, 14a, 14c Electrode body, 15 Case body, 16 Sealing body, 17, 18 Insulating plate, 19 Positive electrode lead, 21 Protruding part, 22 Internal terminal plate, 23 Lower valve body, 24 Insulating member, 25 Upper valve body, 26 Cap, 27 Gasket, 28 Space, 35 Negative electrode core body, 40, 40a, 40b, 40d First tape, 41, 41a, 41b, 41d Second tape, 42, 42a, 42b, 42d, 43, 43d Edge, 50 Tape, 51, 52 Edge.

Claims

1. A non-aqueous electrolyte secondary battery comprising: a bottomed cylindrical case body; a wound electrode body housed in the case body, with a positive electrode and a negative electrode wound around it via a separator; and at least one tape attached to the outermost surface of the electrode body to secure the end of the winding of the electrode body, wherein the negative electrode core constituting the negative electrode is located on the outermost surface of the electrode body and in contact with the inner surface of the case body; and the tape is generally rectangular when stretched along a plane, with at least one edge being non-linear.

2. The non-linear edge of the tape is corrugated, as described in claim 1, for the non-aqueous electrolyte secondary battery.

3. The non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein the at least one tape is two tapes attached along the winding direction to both ends of the electrode body in the winding axis direction on the outermost outer surface of the electrode body, and the edge of at least one end of each of the two tapes in the winding axis direction is non-linear.

4. The non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein the at least one tape is attached to the outermost surface of the electrode body along the winding axis direction of the electrode body, and the edge of at least one end of the tape in the winding direction of the electrode body is non-linear.

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