Cylindrical battery

Abstract

In this cylindrical battery, a negative electrode mixture layer (12b) of a negative electrode (12) extends from a winding inner side of a positive electrode starting end (40), which is a leading end on a winding start side of a positive electrode (11), to the winding start side. In the positive electrode (11), a tape (50) is adhered to a portion including a center (L1) in the winding axis direction of at least one surface of a winding inner surface or a winding outer surface of the positive electrode starting end part. In the positive electrode (11), no tape is adhered to both end parts in the winding axis direction of at least one surface of the positive electrode starting end part.

Description

Cylindrical battery

[0001] The present disclosure relates to a cylindrical battery.

[0002] Conventionally, as a cylindrical battery, there is one described in Patent Document 1. This cylindrical battery includes an electrode body in which a positive electrode and a negative electrode are wound via a separator. In this cylindrical battery, on the negative electrode, a negative electrode lead is attached to a portion wound in a state of not facing the positive electrode through the separator for one or more turns from the inner end in the winding direction, and an insulating tape is attached to the negative electrode core body so as to cover the surface of the negative electrode lead. Thereby, it is said that deformation of the electrode plate accompanying the charge and discharge cycle in the electrode body is suppressed.

[0003] International Publication No. 2018 / 180748

[0004] The inventor of the present case has found that when the cylindrical battery is charged and discharged, the gap between the negative electrodes near the start end of the positive electrode in the electrode body becomes small, and there is a risk that the voltage drops due to the separator intervening in the gap being pressed from near the center in the winding axis direction of the start end of the positive electrode. On the other hand, in a cylindrical battery, it is required to suppress a decrease in battery capacity. Therefore, an object of the present disclosure is to provide a cylindrical battery that can suppress a decrease in battery capacity and can suppress a voltage drop accompanying charge and discharge.

[0005] The cylindrical battery according to the present disclosure includes an electrode body in which a strip-shaped positive electrode having a positive electrode core body and a positive electrode mixture layer and a strip-shaped negative electrode having a negative electrode core body and a negative electrode mixture layer are wound via a separator, a bottomed cylindrical outer can that houses the electrode body, and a sealing body that closes the opening of the outer can. The negative electrode mixture layer extends from the inner side of the winding of the start end of the positive electrode, which is the tip on the winding start side of the positive electrode, to the winding start side. The positive electrode has a tape attached to a portion including the center in the winding axis direction of at least one of the inner winding surface and the outer winding surface of the positive electrode start end portion including the positive electrode start end, and no tape is attached to both ends in the winding axis direction of at least one of the surfaces of the positive electrode start end portion.

[0006] According to the cylindrical battery of this disclosure, the pressure on the separator near the center of the winding axis direction at the positive electrode starting end can be suppressed, thereby suppressing voltage drop associated with charging and discharging. Furthermore, since tape is not attached to the positive electrode mixture layer at both ends of the winding axis direction on at least one surface of the positive electrode starting end, a decrease in battery capacity can be suppressed.

[0007] This is a cross-sectional view along the axial direction of a cylindrical battery according to an embodiment of the present disclosure. In this embodiment, it is a cross-sectional view perpendicular to the winding axis direction of the electrode body, showing the vicinity of the positive electrode starting end. This is a diagram showing the inner surface of the winding of the positive electrode starting end, which is the end on the winding start side of the positive electrode, and the outer surface of the winding of the negative electrode starting end, which is the end on the winding start side of the negative electrode, unfolded in the longitudinal direction. This is a cross-sectional view taken along line A-A in Figure 3. This is an enlarged view of part B in Figure 3 in another example of a cylindrical battery according to the embodiment. This is a cross-sectional view taken along line C-C in Figure 5. This is a diagram corresponding to Figure 5 in another example of a cylindrical battery according to the embodiment. This is a cross-sectional view taken along line D-D in Figure 7. This is a diagram corresponding to Figure 8 in another example of a cylindrical battery according to the embodiment.

[0008] Hereinafter, embodiments of the cylindrical battery according to this disclosure will be described in detail with reference to the drawings. The cylindrical battery of this disclosure may be a primary battery or a secondary battery. It may also be a battery using an aqueous electrolyte or a battery using a non-aqueous electrolyte. In the following, a non-aqueous electrolyte secondary battery (lithium-ion battery) using a non-aqueous electrolyte will be given as an example of a cylindrical battery 10, which is one embodiment, but the cylindrical battery of this disclosure is not limited to this, and the electrolyte may also be an aqueous electrolyte.

[0009] It is intended from the outset that new embodiments can be constructed by appropriately combining the characteristic features of the embodiments and modifications described below. In the following embodiments, the same reference numerals are used for the same components in the drawings, and redundant explanations are omitted. In addition, multiple drawings include schematic diagrams, and the dimensional ratios such as length, width, and height of each component do not necessarily match between different drawings. In this specification, the side of the cylindrical battery 10 with the sealing body 17 in the axial direction (height direction) is referred to as "upper," and the side of the outer casing 16 with the bottom 31 in the axial direction is referred to as "lower." Furthermore, among the components described below, components that are not described in the independent claim indicating the highest-level concept are optional components and are not essential components.

[0010] Figure 1 is a cross-sectional view along the axial direction of a cylindrical battery 10 according to one embodiment of the present disclosure. As shown in Figure 1, the cylindrical battery 10 comprises an electrode body 14, a bottomed cylindrical outer casing 16 that houses the electrode body 14, and a sealing body 17 that closes the opening of the outer casing 16. The outer casing 16 houses a non-aqueous electrolyte together with the electrode body 14. The outer casing 16 has a shoulder portion 29 at its upper end that is bent radially inward and extends inward. The outer casing 16 has a grooved portion 22 formed in its side wall, and the sealing body 17 is supported by the grooved portion 22 and closes the opening of the outer casing 16.

[0011] The cylindrical battery 10 further includes a gasket 28 interposed between the outer casing 16 and the sealing body 17. The gasket 28 is a ring-shaped resin member attached to the outer circumference of the sealing body 17, and insulates the sealing body 17 from the outer casing 16. The gasket 28 seals the gap between the outer casing 16 and the sealing body 17, thereby sealing the inside of the battery. The gasket 28 is made of, for example, polyolefin.

[0012] 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 cylindrical 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.

[0013] 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.

[0014] 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.

[0015] 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 wound in a spiral shape via the separator 13. The positive electrode 11, the negative electrode 12, and the separator 13 are all elongated strip-shaped bodies, and are alternately stacked in the radial direction of the electrode body 14 by being wound in a spiral shape. The negative electrode 12 is formed to be slightly larger in dimensions than the positive electrode 11 in order to prevent lithium deposition. That is, the negative electrode 12 is formed to be longer in the longitudinal and width directions than the positive electrode 11. The separator 13 is formed to be at least slightly larger in dimensions than the positive electrode 11, and for example, two separators are arranged so as to sandwich the positive electrode 11.

[0016] The electrode body 14 is connected to a positive electrode lead 20 and two negative electrode leads 21a and 21b. The positive electrode lead 20 electrically connects the positive electrode 11 to the sealing body 17. The first negative electrode lead 21a is joined to the beginning end of the negative electrode 12, electrically connecting this beginning end to the bottom 31 of the outer container 16. The second negative electrode lead 21b is joined to the end of the negative electrode 12, electrically connecting this end to the bottom 31 of the outer container 16.

[0017] In the example shown in Figure 1, the positive electrode lead 20 extends through the opening in the upper insulating plate 18 toward the sealing body 17 and is joined to the lower surface of the sealing body 17. The first negative electrode lead 21a is bent toward the hollow portion 14a of the electrode body 14, passing through a through hole in the annular lower insulating plate 19. The second negative electrode lead 21b is bent so as to overlap the first negative electrode lead 21a, passing outside the lower insulating plate 19. The overlapping portion of the first negative electrode lead 21a and the second negative electrode lead 21b is resistance welded using a welding rod inserted through the hollow portion 14a of the electrode body 14 and joined to the inner surface of the bottom 31 of the outer can 16.

[0018] When the negative electrode leads 21a and 21b are joined to both ends of the negative electrode 12 in the longitudinal direction, the current collection path of the negative electrode 12 is shortened, thereby reducing the internal resistance of the cylindrical battery 10. Alternatively, the negative electrode leads may be joined only to the end of the negative electrode on the winding end side in the longitudinal direction. Or, the negative electrode leads may be joined only to the end of the negative electrode on the winding start side in the longitudinal direction, and the outermost core exposed portion of the negative electrode core, located at least a part of the outermost circumference of the electrode body, may be in contact with the inner surface of the outer casing 16.

[0019] Figure 2 is a cross-sectional view of the electrode body 14 perpendicular to the winding axis direction, showing the vicinity of the positive electrode start end 40. Figure 3 is a diagram showing the inner surface of the winding of the positive electrode start end, which is the end of the positive electrode 11 that starts winding, and the outer surface of the winding of the negative electrode start end, which is the end of the negative electrode 12 that starts winding and is located on the inner side of the winding of the positive electrode start end, unfolded in the longitudinal direction. The positive electrode start end 40 is the tip of the positive electrode 11 that starts winding, and the positive electrode start end is the region that includes the positive electrode start end 40 and its vicinity. In Figure 2, the cross-section of the positive electrode 11 is shown by the part where the diagonal lines overlap the sandy area. In Figure 2, the separator 13 is shown by a dashed line. In Figure 3, the exposed part of the positive electrode mixture layer 11b is shown by the high-density sandy area, and the part of the positive electrode mixture layer 11b covered with insulating tape 50, or the negative electrode mixture layer 12b, is shown by the low-density sandy area.

[0020] As shown in Figures 2 and 3, the positive electrode 11 has a positive electrode core 11a and a positive electrode mixture layer 11b formed on both sides of the positive electrode core 11a. The positive electrode core 11a can be made of a metal foil that is stable in the potential range of the positive electrode 11, such as aluminum or an aluminum alloy, or a film with the metal arranged on its surface. The positive electrode mixture layer 11b contains a positive electrode active material, a conductive agent such as acetylene black, and a binder such as polyvinylidene fluoride (PVdF). For example, a lithium transition metal composite oxide containing Ni, Co, Mn, Al, etc., can be used as the positive electrode active material. The positive electrode lead 20 is connected to the positive electrode 11, but it is preferable that it is directly joined to the positive electrode core 11a by ultrasonic welding or the like, and it is preferable that the joint portion with respect to the positive electrode core 11a is covered with insulating tape.

[0021] The negative electrode 12 comprises a negative electrode core 12a and a negative electrode mixture layer 12b formed on both sides of the negative electrode core 12a. The negative electrode core 12a can be made of a metal foil that is stable in the potential range of the negative electrode 12, such as copper or a copper alloy, or a film with the metal arranged on its surface. The negative electrode mixture layer 12b contains a negative electrode active material and a binder such as styrene-butadiene rubber (SBR) or PVdF. For example, graphite or a silicon-containing compound can be used as the negative electrode active material. The negative electrode leads 21a and 21b are preferably directly joined to the negative electrode core 12a by ultrasonic welding or the like, and the joint portion with respect to the negative electrode core 12a is preferably covered with insulating tape. For example, in Figure 3, the first negative electrode lead 21a is joined to the end of the negative electrode 12 on the winding start side, and the joint portion of the first negative electrode lead 21a with respect to the negative electrode core 12a is covered with insulating tape 15.

[0022] In the negative electrode 12, the negative electrode mixture layer 12b formed on at least one surface of the negative electrode core 12a has an extended portion 38 that extends from a radially opposing position A1 of the electrode body 14 via a separator 13 with respect to the winding side of the positive electrode start end 40 toward the winding start side of the electrode body 14. The extended portion 38 extends toward the winding start side for, for example, 1 / 5 of a turn or more, preferably 1 / 2 of a turn or more, and more preferably 1 turn or more. When this extended portion 38 is wound toward the winding start side of the electrode body 14 for a predetermined length or more, for example 1 / 2 of a turn or more, from the position A1 opposing the positive electrode start end 40 toward the winding start side of the electrode body 14, it becomes easier to maintain the shape of the hollow portion 14a, which is a cylindrical space formed in the winding core of the electrode body 14.

[0023] Referring to Figure 1, the outer can 16 is generally made of a metal mainly composed of iron, for example, iron plated with nickel, but it may also be made of a metal mainly composed of aluminum or the like. The outer can 16 has a cylindrical portion 39 and a bottom portion 31, and the cylindrical portion 39 includes an annular grooved portion 22 and an annular shoulder portion 29. The grooved portion 22 is formed by spinning a part of the cylindrical portion 39 to create a recess on the radially inward side. The shoulder portion 29 is formed when the upper end (one end in the axial direction) of the cylindrical portion 39 is bent radially inward and crimped to the peripheral edge 33 of the sealing body 17, and extends radially inward at the upper end of the cylindrical portion 39.

[0024] The sealing body 17 is fixed to the outer can 16 by crimping, with a gasket 28 between the shoulder portion 29 and the grooved portion 22. The grooved portion 22 is formed at a predetermined distance from the upper end of the outer can 16. The predetermined length is, for example, 1% to 20% of the winding axial length of the outer can 16.

[0025] The sealing body 17 has a structure in which an internal terminal plate 23, a lower valve body 24, an insulating plate 25, an upper valve body 26, and a sealing plate 27 are stacked in this order from the electrode body 14 side. Each component constituting the sealing body 17 has, for example, a disc shape or a ring shape, and each component except the insulating plate 25 is electrically connected to one another. The sealing plate 27 has a convex shape with its radial center portion protruding outward. The convex portion 27a of the sealing plate 27 includes an annularly formed inclined portion and a flat top portion surrounded by the inclined portion. One or more ventilation holes 27b are formed in the top portion.

[0026] The lower valve body 24, the insulating plate 25, and the upper valve body 26 constitute a current interruption mechanism. The lower valve body 24 and the upper valve body 26 are connected at their respective centers, with the insulating plate 25 interposed between their respective peripheries. When an abnormality occurs in the cylindrical battery 10 and the internal pressure rises to a predetermined value, the lower valve body 24 deforms and ruptures, pushing the upper valve body 26 towards the sealing plate 27, thereby interrupting the current path between the lower valve body 24 and the upper valve body 26. If the internal pressure rises further and reaches a predetermined value, the upper valve body 26 ruptures, and gas is discharged from the vent hole 27b of the sealing plate 27.

[0027] In this embodiment, the positive lead 20 is connected to the lower surface of the internal terminal plate 23 by laser welding or ultrasonic welding, and the sealing plate 27, which is the top plate of the sealing body 17 electrically connected to the internal terminal plate 23, becomes the positive terminal. The outer casing 16 to which the negative leads 21a and 21b are joined becomes the negative terminal.

[0028] In this embodiment, in order to suppress the decrease in battery capacity of the cylindrical battery 10 and to suppress the voltage drop associated with charging and discharging, insulating tape 50 is attached to only a portion of the positive electrode width direction, which is the winding axis direction, on both the inner and outer surfaces of the winding at the starting end of the positive electrode.

[0029] Specifically, the positive electrode 11 has insulating tape 50 attached to the portion of both the inner and outer surfaces of the winding at the starting end of the positive electrode that includes the center L1 in the positive electrode width direction (Figures 3 and 4). In this example, each insulating tape 50 is evenly distributed on both sides in the positive electrode width direction with respect to the center L1 in the positive electrode width direction. That is, the longitudinal center of each insulating tape 50 coincides with the center L1 in the positive electrode width direction.

[0030] At the positive electrode starting end of the positive electrode 11, the insulating tape 50 is not attached to both ends in the positive electrode width direction, and the positive electrode mixture layer 11b is exposed. Note that the positive electrode mixture layer 11b at both ends in the positive electrode width direction does not necessarily need to be exposed; for example, a coating layer that does not inhibit the charge-discharge reaction of the positive electrode mixture layer 11b, such as a porous filler layer containing inorganic particles, may be provided.

[0031] The insulating tape 50 is an adhesive tape having a base layer and an adhesive layer formed on the side of the base layer that adheres to the positive electrode 11. A heat-resistant layer containing inorganic particles such as metal oxides can be provided between the base layer and the adhesive layer. The base layer can be any insulating resin, such as PPS (polyphenylene sulfide), PEEK (polyether ether ketone), PI (polyimide), PP (polypropylene), PET (polyethylene terephthalate), PBT (polybutylene terephthalate), etc.

[0032] The adhesive layer may contain at least one of a rubber-based polymer or an acrylic-based polymer. The adhesive layer may further contain, for example, a silicone-based polymer.

[0033] The length Lb (Figure 4) of the insulating tape 50 in the positive electrode width direction is preferably 1 / 3 or more and 2 / 3 or less of the length La (Figure 4) of the positive electrode 11 in the positive electrode width direction. In the insulating tape 50, the length Lc (Figure 3) in the positive electrode longitudinal direction, which is the winding direction of the portion that covers the inner and outer surfaces of the winding of the positive electrode 11, is preferably 1 mm or more and 5 mm or less.

[0034] Furthermore, in this example, the starting end of each insulating tape 50 coincides with the positive electrode starting end 40 and the longitudinal direction of the positive electrode. To obtain such a positive electrode 11, for example, when manufacturing multiple positive electrodes 11 by cutting a long plate-shaped positive electrode material at equally spaced positions in the longitudinal direction, insulating tape having a width twice the length Lc (Figure 3) of the insulating tape 50 can be pre-attached to multiple positions on both sides of the positive electrode material so as to straddle the planned cutting positions of the positive electrode material. In this case, the positive electrode material is cut along with the insulating tape at the planned cutting positions, and each insulating tape is divided into two. This makes it possible to obtain a positive electrode 11 with insulating tape 50 attached to its end.

[0035] During charging and discharging of the cylindrical battery 10, the electrode body 14 tends to bulge more near the center in the winding axis direction than near both ends in the winding axis direction, and the pressure tends to be higher near the center in the winding axis direction. According to this embodiment, since the insulating tape 50 covers the portion including the center L1 in the positive electrode width direction on both sides of the positive electrode starting end, it is possible to suppress the pressure on the separator 13 from the area near the center L1 in the positive electrode width direction of the positive electrode starting end 40. This makes it possible to suppress the voltage drop associated with charging and discharging of the cylindrical battery 10.

[0036] The insulating tape 50 is not attached to both ends in the positive electrode width direction of the positive electrode starting end on both sides of the positive electrode 11, and the positive electrode mixture layer 11b is exposed. This helps to suppress a decrease in battery capacity.

[0037] In the first configuration, where the length Lb (Figure 4) of the insulating tape 50 in the positive electrode width direction is 1 / 3 or more and 2 / 3 or less of the length La (Figure 4) of the positive electrode 11 in the positive electrode width direction, it becomes easier to achieve both the effect of suppressing battery capacity reduction and the effect of suppressing voltage reduction. In the second configuration, where the length Lc (Figure 3) in the positive electrode longitudinal direction of the portion covering the inner and outer surfaces of the winding of the positive electrode 11 is 1 mm or more and 5 mm or less, it also becomes easier to achieve both the effect of suppressing battery capacity reduction and the effect of suppressing voltage reduction. In the embodiment, by incorporating both the first and second configurations described above, it becomes even easier to achieve both the effect of suppressing battery capacity reduction and the effect of suppressing voltage reduction.

[0038] [Another Embodiment] Figure 5 is an enlarged view of section B in Figure 3, showing a cylindrical battery according to another embodiment. Figure 6 is a cross-sectional view taken along line C-C in Figure 5.

[0039] In the structure of this example, in the positive electrode 11, an insulating tape 51 is adhered to a portion including the width direction center L1 in the winding axis direction on each of the inner winding surface and the outer winding surface at the start end portion of the positive electrode. Also, on each of the two surfaces of the positive electrode 11, in at least a part of the portion covered by the insulating tape 51, a positive electrode active material layer is not provided on the surface of the positive electrode core 11a.

[0040] Specifically, in this example, in the positive electrode 11, a core exposed portion 11a1 where a positive electrode active material layer is not provided on the positive electrode core 11a is provided in a portion including the positive electrode width direction center L1 on both the inner winding surface and the outer winding surface at the start end portion of the positive electrode. In the illustrated example, the core exposed portion 11a1 has a rectangular shape when viewed from the outside in the thickness direction.

[0041] The insulating tape 51 is adhered to the surface of the positive electrode active material layer 11b and the core exposed portion 11a1 so as to cover the core exposed portion 11a1 and a peripheral portion along the outer edge of the core exposed portion 11a1.

[0042] According to the structure of this example, the amount of the positive electrode active material layer 11b covered by the insulating tape 51 can be reduced, so that the wasted coating amount of the positive electrode active material layer 11b can be reduced. For example, during the manufacture of the positive electrode 11, when discharging and applying a positive electrode active material slurry from a discharge port onto the surface of the positive electrode core 11a while moving the positive electrode core 11a in the positive electrode longitudinal direction, the discharge of the positive electrode active material slurry from the discharge port is stopped at a portion that is expected to become the core exposed portion 11a1 near the start end 40 of the positive electrode. Note that the shape of the core exposed portion 11a1 when viewed from the outside in the thickness direction is not limited to a rectangular shape, and for example, it can also be a semi-elliptical shape obtained by dividing an ellipse in the short axis direction into half. In this example, other structures and operations are the same as those in FIGS. 1 to 4.

[0043] FIG. 7 is a view corresponding to FIG. 5 in a cylindrical battery of another example of the embodiment. FIG. 8 is a cross-sectional view taken along the line D - D of FIG. 7.

[0044] In this example, at the positive electrode 11, insulating tape 52 is attached to both the inner and outer surfaces of the winding, which are both the thickness-direction surfaces of the positive electrode starting end, in a portion that includes the center L1 in the positive electrode width direction, which is the winding axis direction. In this example, the two insulating tapes 52 have extension portions 53 that extend further towards the winding start side than the positive electrode starting end 40 at the winding start side. The extension portions 53 of the two insulating tapes 52 are overlapped and bonded to each other in the portion that includes the winding start end of the insulating tape 52. As a result, the end face of the positive electrode starting end 40, which is sandwiched between both thickness-direction surfaces of the positive electrode starting end, is covered with insulating tape 52. At this time, the insulating tape 52 does not necessarily need to be attached to the end face of the positive electrode starting end 40.

[0045] In this example, the extension portion 53 of each insulating tape 52, which extends beyond the positive electrode start end 40 towards the winding start end, makes it easier to suppress deformation of the negative electrode. In addition, at the center of the positive electrode width direction of the positive electrode 11, the end face of the positive electrode start end 40 is covered with the insulating tape 52. This further suppresses the voltage drop of the cylindrical battery. In this example, the other configurations and operations are the same as those in Figures 1 to 4.

[0046] Figure 9 is a diagram of a cylindrical battery in another embodiment, corresponding to Figure 8. In this example, at the positive electrode 11, insulating tape 54 is attached in a substantially U-shape in cross-section to the portion including the center in the positive electrode width direction on both the inner and outer surfaces of the winding at the positive electrode starting end, and to the end face 41 of the positive electrode starting end 40. In this example, both sides of a single insulating tape 54 are attached to both the inner and outer surfaces of the winding at the positive electrode starting end, thus reducing the number of parts. Also, in this example, similar to the configurations in Figures 7 to 8, the end face 41 of the positive electrode starting end 40 is covered with insulating tape 54 at the center in the positive electrode width direction of the positive electrode 11. This further suppresses the voltage drop of the cylindrical battery. In this example, the other configurations and operations are the same as those in Figures 1 to 4.

[0047] The present disclosure is not limited to the above-described embodiments and their modifications, and various improvements and changes can be made within the matters described in the claims of the present application and their equivalent scope. For example, in each of the above examples, insulating tapes are evenly adhered to both sides of the inner and outer winding surfaces of the starting end of the positive electrode, including the central portion in the width direction of the positive electrode. On the other hand, insulating tapes may be adhered only to one of the inner and outer winding surfaces of the starting end of the positive electrode. Further, if insulating tapes are adhered to a portion including the central portion in the width direction of one or both sides of the starting end of the positive electrode, the lengths in the width direction of the exposed portions of the positive electrode mixture layer at both ends in the width direction of the starting end of the positive electrode may be made different from each other as necessary.

[0048] The present disclosure will be further described by the following embodiments. Configuration 1: A cylindrical battery comprising a strip-shaped positive electrode having a positive electrode core and a positive electrode mixture layer, and a strip-shaped negative electrode having a negative electrode core and a negative electrode mixture layer, wound through a separator; a bottomed cylindrical outer can for housing the electrode body; and a sealing body for closing the opening of the outer can. The negative electrode mixture layer extends from the inner side of the winding of the starting end of the positive electrode, which is the tip on the starting side of the winding of the positive electrode, to the starting side. The positive electrode has a tape adhered to a portion including the central portion in the winding axis direction of at least one of the inner and outer winding surfaces of the starting end portion of the positive electrode including the starting end of the positive electrode. In the positive electrode, the tape is not adhered to both ends in the winding axis direction of at least one of the surfaces of the starting end portion of the positive electrode. Configuration 2: The cylindrical battery according to Configuration 1, wherein the length of the tape in the winding axis direction is 1 / 3 or more and 2 / 3 or less of the length of the positive electrode in the winding axis direction. Configuration 3: The cylindrical battery according to Configuration 1 or Configuration 2, wherein the length in the winding direction of the portion covering at least one of the surfaces of the tape is 1 mm or more and 5 mm or less. Configuration 4: The cylindrical battery according to any one of Configurations 1 to 3, wherein the tape is adhered to both surfaces in the thickness direction of the starting end portion of the positive electrode and covers the end face of the starting end of the positive electrode, and the portion of the tape extending from the starting end of the positive electrode to the starting side is overlapped and adhered in a sheet shape.

[0049] 10 Cylindrical battery, 11 Positive electrode, 11a Positive electrode core, 11a1 Core exposed portion, 11b Positive electrode mixture layer, 12 Negative electrode, 12a Negative electrode core, 12b Negative electrode mixture layer, 13 Separator, 14 Electrode body, 14a Hollow portion, 15 Insulating tape, 16 Outer can, 17 Sealing body, 18 Upper insulating plate, 19 Lower insulating plate, 20 Positive electrode lead, 21a First negative electrode lead, 21b Second negative electrode lead, 22 Grooved portion, 23 Terminal plate, 24 Lower valve body, 25 Insulating plate, 26 Upper valve body, 27 Sealing plate, 27a Protrusion, 27b Ventilation hole, 28 Gasket, 29 Shoulder portion, 31 Bottom, 33 Peripheral portion, 38 Extension portion, 39 Cylindrical portion, 40 Positive terminal starting end, 41 End face, 50, 51, 52 Insulating tape, 53 Extension portion, 54 Insulating tape.

Claims

1. A cylindrical battery comprising: an electrode body in which a strip-shaped positive electrode having a positive electrode core and a positive electrode mixture layer, and a strip-shaped negative electrode having a negative electrode core and a negative electrode mixture layer are wound via a separator; a bottomed cylindrical outer can housing the electrode body; and a sealing body closing the opening of the outer can, wherein the negative electrode mixture layer extends from the inside of the winding to the winding start side of the positive electrode starting end, which is the tip of the winding start side of the positive electrode; tape is attached to the portion of at least one surface of the winding inner surface and the winding outer surface of the positive electrode starting end, including the positive electrode starting end, including the center in the winding axis direction; and tape is not attached to both ends in the winding axis direction of at least one surface of the positive electrode starting end of the positive electrode.

2. The length of the tape in the winding axis direction is 1 / 3 or more and 2 / 3 or less of the length of the positive electrode in the winding axis direction, as described in claim 1.

3. The cylindrical battery according to claim 1, wherein the length in the winding direction of the portion of the tape covering at least one surface is 1 mm or more and 5 mm or less.

4. The cylindrical battery according to claim 1, wherein the tape is attached to both sides in the thickness direction of the positive electrode starting end and covers the end face of the positive electrode starting end.

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