Secondary battery

Abstract

A first surface of the positive electrode (11) is provided with a first core exposed portion (41a) to which the positive electrode lead (20) is joined, and a second surface is provided with a second core exposed portion (41b) at least partially overlapping the first core exposed portion (41a) in the thickness direction of the positive electrode (11). The tip of a second non-trailing portion (58) provided on the second surface is disposed so as to face a first flat portion (42c) of a first mixture layer (42a) adjacent to a first trailing portion (57) provided on the first surface in the thickness direction of the positive electrode (11). The tip of a first non-trailing portion (48) provided on the first surface and a second flat portion (42d) of a second mixture layer (42b) adjacent to a second trailing portion (57) provided on the second surface are disposed so as to face each other in the thickness direction of the positive electrode (11).

Description

Secondary batteries Technical Field

[0001] This invention relates to a secondary battery. Background Technology

[0002] Conventionally, a cylindrical battery as described in Patent Document 1 has been used as a rechargeable battery. This cylindrical battery comprises an electrode body wound along its length with a positive and negative electrode separated by a spacer, a bottomed cylindrical outer packaging can housing the electrode body, and a sealing body clamped and fixed to the opening of the outer packaging can with a gasket. A positive electrode core is exposed at the middle of the positive electrode along its length, held in place by a positive electrode binder layer. One end of a positive electrode lead is attached to this exposed positive electrode core, and the other end of the positive electrode lead is attached to the inner surface of the sealing body. Furthermore, one end of a negative electrode lead is attached to the end of the winding of the negative electrode, and the other end of the negative electrode lead is attached to the inner surface of the bottom of the outer packaging can.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Re-registration No. 2019-044770 Summary of the Invention

[0006] In the electrodes of a secondary battery, the flux layer expands and contracts during charging and discharging, but the exposed core does not. Therefore, when the exposed core is located in the middle of the electrode's length, wrinkles and other deformations are easily generated in the core at the boundary between the flux layer formation area and the exposed core.

[0007] Therefore, the object of the present invention is to provide a cylindrical battery in which the boundary between the compound layer forming area and the exposed core is not easily deformed in the core.

[0008] To address the aforementioned issues, the cylindrical battery of the present invention comprises an electrode body formed by winding two electrodes of different polarities together along the length direction, separated by a spacer. One electrode has a first exposed core portion on its first surface, which is configured to be held along the length direction by a first adhesive layer provided on the first surface and simultaneously joined with electrode leads. The second electrode has a second exposed core portion on its second surface, which is also configured to be held along the length direction by a second adhesive layer provided on the second surface and at least a portion thereof is disposed opposite to the first exposed core portion in the thickness direction. The first adhesive layer has a first trailing portion and a first non-trailing portion. The first trailing portion is adjacent to the end of the first exposed core portion on its first side along the length direction and has a plurality of first trailing portions extending along the length direction. The first non-tail portion is adjacent to the end of the first core exposed portion on the second side of the length direction, while its front end extends in the approximate width direction. The second compound layer has a second non-tail portion and a second tail portion. The second non-tail portion is adjacent to the end of the second core exposed portion on the first side of the length direction, while its front end extends in the approximate width direction. The second tail portion is adjacent to the end of the second core exposed portion on the second side of the length direction, while having a plurality of second tails extending in the length direction. The front end of the second non-tail portion is disposed opposite to the first flat portion of the first compound layer in the thickness direction. The first flat portion of the first compound layer is adjacent to the first tail portion. The front end of the first non-tail portion is disposed opposite to the second flat portion of the second compound layer in the thickness direction. The second flat portion of the second compound layer is adjacent to the second tail portion.

[0009] According to the secondary battery of the present invention, the boundary between the compound layer forming area and the exposed core is less prone to deformation of the core. Attached Figure Description

[0010] Figure 1 is an axial cross-sectional view of a cylindrical battery according to an embodiment of the present invention.

[0011] Figure 2 is a top view of the periphery of the exposed portion of the first core, to which the positive electrode lead is joined, on the wound outer surface of the first face that constitutes the positive electrode.

[0012] Figure 3 is a cross-sectional view along line AA of Figure 2.

[0013] Figure 4 is a cross-sectional view of the battery of the reference example, corresponding to Figure 3.

[0014] Figure 5 is a top view of the modified battery corresponding to Figure 2. Detailed Implementation

[0015] Hereinafter, embodiments of the secondary battery of the present invention will be described in detail with reference to the accompanying drawings. The secondary battery of the present invention can be any secondary battery having a wound electrode body; it can be a secondary battery using an aqueous electrolyte or a secondary battery using a non-aqueous electrolyte. The secondary battery of the present invention can be a cylindrical battery with a bottom cylindrical outer packaging can, a square battery with a square outer packaging can, or a pouch battery with an outer packaging body composed of a laminate containing a metal layer and a resin layer. Hereinafter, a cylindrical battery (lithium-ion battery) using a non-aqueous electrolyte will be exemplified as one embodiment of the secondary battery; however, the secondary battery of the present invention is not limited to this.

[0016] From the outset, it was envisioned that new embodiments could be constructed by appropriately combining the characteristic features of the following described embodiments and variations. In the following embodiments, the same symbols are used to label the same components in the drawings, and repeated descriptions are omitted. Furthermore, the multiple drawings include schematic diagrams, and the dimensional ratios of the components, such as longitudinal, transverse, and height, may not be consistent between different drawings. In this specification, the axial (height direction) sealing body 17 side of the cylindrical battery 10 is designated as "upper," and the axial bottom 68 side of the outer packaging can 16 is designated as "lower." Among the constituent elements described below, those not described in the independent technical solution representing the highest-level concept are optional, not essential, constituent elements.

[0017] Figure 1 is an axial cross-sectional view of a cylindrical battery 10 according to an embodiment of the present invention. As shown in Figure 1, the cylindrical battery (hereinafter referred to as the battery) 10 includes a wound electrode body 14, a non-aqueous electrolyte (not shown), a bottomed cylindrical metal outer packaging can 16 for housing the electrode body 14 and the non-aqueous electrolyte, and a sealing body 17 for sealing the opening of the outer packaging can 16. The electrode body 14 has a wound structure formed by winding a strip-shaped positive electrode 11 and a strip-shaped negative electrode 12 along the length direction, with two strip-shaped spacers 13 sandwiched between them.

[0018] To prevent lithium deposition, the negative electrode 12 is formed to be one size larger than the positive electrode 11. The negative electrode 12 is longer in both the length and width directions (short side direction) compared to the positive electrode 11. Two spacers 13 are formed to be at least one size larger than the positive electrode 11, for example, in a manner that clamps the positive electrode 11. The negative electrode 12 can constitute the winding start end of the electrode body 14. However, generally, the spacers 13 extend beyond the winding start end of the negative electrode 12, and the winding start end of the spacers 13 becomes the winding start end of the electrode body 14.

[0019] Non-aqueous electrolytes possess ionic conductivity (e.g., lithium-ion conductivity). Non-aqueous electrolytes can be liquid electrolytes (electrolytes) or solid electrolytes. Liquid electrolytes (electrolytes) comprise a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Examples of non-aqueous solvents include esters, ethers, nitriles, amides, and mixtures of two or more of these. Examples of non-aqueous solvents include ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and mixtures thereof. Non-aqueous solvents may contain halogen-substituted derivatives (e.g., fluoroethylene carbonate) in which at least a portion of the hydrogen atoms of these solvents are replaced by halogen atoms such as fluorine. Examples of electrolyte salts used include lithium salts such as LiPF6.

[0020] As solid electrolytes, examples include solid or gel-like polymer electrolytes and inorganic solid electrolytes. Polymer electrolytes may contain, for example, lithium salts and a matrix polymer, or non-aqueous solvents, lithium salts, and a matrix polymer. As a matrix polymer, examples include polymer materials that gel upon absorbing non-aqueous solvents. As polymer materials, examples include fluoropolymers, acrylic resins, and polyether resins. As inorganic solid electrolytes, examples include materials known in all-solid-state lithium-ion secondary batteries (e.g., oxide-based solid electrolytes, sulfide-based solid electrolytes, halide-based solid electrolytes, etc.).

[0021] The positive electrode 11 has a positive electrode core 41 (see Figure 3) and positive electrode additive layers 42 formed on both sides of the positive electrode core (see Figure 3). The positive electrode core 41 can be a foil of a metal that is stable in the potential range of the positive electrode 11, such as aluminum or an aluminum alloy, or a film on which the metal is disposed on the surface. The positive electrode additive layers 42 contain a positive electrode active material, a conductive agent, and a binder. For example, a positive electrode additive slurry containing a positive electrode active material, a conductive agent, and a binder can be coated on the positive electrode core 41, and after the coating is dried, it is compressed to form the positive electrode additive layers 42 on both sides of the positive electrode core 41, thereby manufacturing the positive electrode 11.

[0022] The positive electrode active material is mainly composed of lithium-containing metal composite oxides. Examples of metal elements contained in these lithium-containing metal composite oxides include Ni, Co, Mn, Al, B, Mg, Ti, V, Cr, Fe, Cu, Zn, Ga, Sr, Zr, Nb, In, Sn, Ta, and W. A preferred example of a lithium-containing metal composite oxide is one containing at least one of Ni, Co, Mn, or Al.

[0023] Examples of conductive agents contained in the positive electrode binder layer 42 include carbon materials such as carbon black, acetylene black, Ketjen black, and graphite. Examples of binders contained in the positive electrode binder layer include fluoropolymers such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyimide resins, acrylic resins, and polyolefin resins. These resins may also be used in combination with cellulose derivatives such as carboxymethyl cellulose (CMC) or its salts, and polyethylene oxide (PEO).

[0024] The negative electrode 12 has a negative electrode core and negative electrode binder layers formed on both sides of the negative electrode core. The negative electrode core can be a metal foil, such as copper or a copper alloy, that is stable within the potential range of the negative electrode 12, or a film with the same metal disposed on its surface. The negative electrode binder layers contain a negative electrode active material and a binder. For example, the negative electrode 12 can be manufactured by coating a negative electrode binder slurry containing a negative electrode active material and a binder onto the negative electrode core, drying the coating, and then compressing it to form negative electrode binder layers on both sides of the negative electrode core.

[0025] The negative electrode active material typically uses carbon materials that reversibly absorb and release lithium ions. Preferred carbon materials include natural graphite such as flake graphite, block graphite, and amorphous graphite, as well as artificial graphite such as block graphite and graphitized mesophase carbon microspheres. The negative electrode additive layer may also contain silicon (Si) materials as the negative electrode active material. Alternatively, the negative electrode active material may also use metals other than Si alloyed with lithium, alloys containing such metals, or compounds containing such metals.

[0026] The binder contained in the negative electrode binder layer can be the same as that in the case of the positive electrode 11, such as fluoropolymer, PAN, polyimide resin, acrylic resin, polyolefin resin, etc., with styrene-butadiene rubber (SBR) or its modified form preferred. The negative electrode binder layer may also contain, for example, CMC or its salt, polyacrylic acid (PAA) or its salt, polyvinyl alcohol, etc., in addition to SBR.

[0027] The spacer 13 can be a porous sheet with ion permeability and insulation. Specific examples of porous sheets include microporous films, woven fabrics, and nonwoven fabrics. The preferred material for the spacer 13 is polyolefin resin such as polyethylene or polypropylene, or cellulose. The spacer 13 can be either a single-layer structure or a multilayer structure. A heat-resistant layer can be formed on the surface of the spacer 13.

[0028] As shown in Figure 1, the positive electrode lead 20 is electrically connected to the middle portion, such as the center portion, of the positive electrode core 41 (see Figure 3) in the winding direction, and the negative electrode lead 21 is electrically connected to the end portion of the negative electrode core in the winding direction at the winding end. The battery 10 has an insulating plate 18 above the electrode body 14 and an insulating plate 19 below the electrode body 14. The positive electrode lead 20 extends through a through hole in the insulating plate 18 toward the sealing body 17, and the negative electrode lead 21 extends through the outside of the insulating plate 19 toward the bottom 68 of the outer packaging can 16. The positive electrode lead 20 is connected to the lower surface of the terminal plate 23 of the sealing body 17 by welding or the like. The terminal cap 27, which constitutes the top plate of the sealing body 17, is electrically connected to the terminal plate 23, and the terminal cap 27 becomes the positive terminal. Furthermore, the negative electrode lead 21 is connected to the inner surface of the bottom 68 of the metal outer packaging can 16 by welding or the like, and the outer packaging can 16 becomes the negative terminal.

[0029] The battery 10 includes a resin gasket 28 disposed between the outer packaging can 16 and the sealing body 17. The sealing body 17 is clamped and fixed to the opening of the outer packaging can 16 with the gasket 28 in between. Thus, the internal space of the battery 10 is sealed. The gasket 28, held between the outer packaging can 16 and the sealing body 17, insulates the sealing body 17 relative to the outer packaging can 16. The gasket 28 serves as a sealing material for maintaining the airtightness of the battery's interior and as an insulating material for insulating the outer packaging can 16 from the sealing body 17.

[0030] The outer packaging can 16 has a cylindrical portion 30 and a bottom 68. The cylindrical portion 30 includes an annular slotted portion 34 and an annular shoulder portion 38. The slotted portion 34 is formed by spinning a portion of the cylindrical portion 30 to make it recessed radially inward. The shoulder portion 38 is formed by bending the upper end of the cylindrical portion 30 radially inward and hemming it tightly against the periphery 35 of the sealing body 17, and extends radially inward from the upper end of the cylindrical portion 30.

[0031] The sealing body 17 has a structure in which a terminal plate 23, a lower valve body 24, an insulating member 25, an upper valve body 26, and a terminal cap 27 are stacked sequentially from the electrode body 14 side. Each component constituting the sealing body 17 is, for example, circular or annular, and all components except the insulating plate 25 are electrically connected to each other. The terminal plate 23 has at least one through hole 23a. The lower valve body 24 and the upper valve body 26 are connected at their respective central portions, and the insulating member 25 is sandwiched between their respective peripheral portions. The terminal cap 27 has a convex shape that protrudes outward from its radial central portion.

[0032] When the internal pressure of battery 10 rises due to abnormal heating, the lower valve body 24 deforms and breaks by pushing the upper valve body 26 towards the terminal cap 27, thus blocking the current path between the lower valve body 24 and the upper valve body 26. When the internal pressure rises further, the upper valve body 26 breaks, and gas is discharged from the through hole 27a of the terminal cap 27. By discharging this gas, the excessive rise in internal pressure of battery 10 can be prevented, thus preventing battery 10 from rupturing and improving the safety of battery 10.

[0033] The sealing body 17 has been described as having a stacked structure comprising two rupture plates (lower valve body 24 and upper valve body 26) and a convex terminal cap 27 covering the rupture plates. However, the sealing body may also consist solely of rupture plates, or it may have a structure in which an inner terminal plate, an insulating plate, and a rupture plate are stacked sequentially from the electrode body side. Alternatively, the sealing body may not have rupture plates, but the bottom of the outer packaging can has a thin-walled, easily fractured portion that breaks when the battery overheats abnormally.

[0034] The structure of the positive electrode 11 will be further described in detail below using Figures 2 to 4. Figure 2 is a top view of the periphery of the first core exposed portion 41a, to which the positive electrode lead 20 is joined, in the wound outer surface 51 constituting the first side of the positive electrode 11. Figure 3 is a cross-sectional view along line AA in Figure 2, which is a cross-sectional view of the battery 10 when cut with a cutting surface that includes both the length and thickness directions and passes through the positive electrode lead 20. In Figure 2, the outer edge of the insulating tape 61a is indicated by an imaginary line.

[0035] As shown in Figure 2, the first core exposed portion 41a of the positive electrode lead 20, which is one example of an electrode lead, is configured such that it is held along the length direction by a first compound layer 42a formed in the positive electrode compound layer 42 on the outer surface 51. In addition, a portion of the first compound layer 42a is arranged to be adjacent to the first core exposed portion 41a in the width direction.

[0036] The first compound layer 42a is manufactured as shown below. The annular positive electrode core 41 is wound out using a drive roller (not shown), and conveyed at a constant speed along one side of the length direction, causing it to travel at a constant speed below the first and second discharge portions (not shown) where the positive electrode compound slurry is discharged. At this time, in the width direction of the positive electrode core 41, the positive electrode compound slurry is intermittently discharged from the second discharge portion to the area forming the first core exposed portion 41a, and continuously discharged from the first discharge portion to the area adjacent to the first core exposed portion 41a in the width direction where the first compound layer 42a is formed. In the length direction, the positive electrode compound slurry is not discharged from the second discharge portion in the area forming the first core exposed portion 41a. By performing this discharge of the positive electrode compound slurry, the first compound layer 42a shown in FIG. 2 is formed.

[0037] As shown in Figures 2 and 3, in the first compound layer 42a formed along with the discharge of this positive electrode compound slurry, no tail is formed at the beginning of the discharge of the positive electrode compound slurry. However, a comb-shaped tail portion 47 is formed near the discharge end of the positive electrode compound slurry when viewed from above the positive electrode 11. Specifically, the first compound layer 42a has a first tail portion 47 and a first non-tail portion 48. The first tail portion 47 is adjacent to the end of the positive electrode 11 on the first side in the length direction of the first core exposed portion 41a and has a plurality of first tails 47a extending along the length direction of the positive electrode 11. The first non-tail portion 48 is adjacent to the end of the positive electrode 11 on the second side in the length direction of the first core exposed portion 41a and extends at its front end in the approximate width direction.

[0038] The first side of the positive electrode 11 along its length direction coincides with the winding start side of the positive electrode 11, and the second side of the positive electrode 11 along its length direction coincides with the winding end side of the positive electrode 11. On the winding inner surface 52 constituting the second surface of the positive electrode 11, a second compound layer 42b is also formed by discharging positive electrode compound slurry into the positive electrode core 41 in the same manner as described above. At the same time, a second core exposed portion 41b is formed, which is sandwiched by the second compound layer 42b and is at least partially disposed opposite to the first core exposed portion in the thickness direction.

[0039] Although not shown, a second compound layer 42b with the same planar shape as the first compound layer 42a is also formed on the inner surface 52 of the positive electrode 11. A portion of the second compound layer 42b is arranged adjacent to the second core exposed portion 41b in the width direction. As shown in FIG3, the second compound layer 42b has a second non-tail portion 58 and a second tail portion 57. The second non-tail portion 58 is adjacent to the end of the positive electrode 11 on the first side in the length direction of the second core exposed portion 41b, while the front end extends in the approximate width direction. The second tail portion 57 is adjacent to the end of the positive electrode 11 on the second side in the length direction of the second core exposed portion 41b, while having a plurality of second tails 57a extending in the length direction of the positive electrode 11.

[0040] The front end of the second non-tailed portion 58 and the first flat portion 42c of the first compound layer 42a are disposed opposite each other in the thickness direction of the positive electrode 11. The first flat portion 42c of the first compound layer 42a and the first tailed portion 47 are adjacent to each other in the length direction of the positive electrode 11. The front end of the first non-tailed portion 48 and the second flat portion 42d of the second compound layer 42b are disposed opposite each other in the thickness direction of the positive electrode 11. The second flat portion 42d of the second compound layer 42b and the second tailed portion 57 are adjacent to each other in the length direction of the positive electrode 11. Insulating tapes 61a and 61b are attached to the front and back sides of the positive electrode 11, covering the positive electrode lead 20 and the exposed core portions 41a and 41b.

[0041] Figure 4 is a cross-sectional view of the reference example battery 210 corresponding to Figure 3. In the positive electrode 211 of the reference example battery 210, the front end of the second non-tail portion 258 and the first tail portion 247 are arranged opposite to each other in the thickness direction of the positive electrode 211, and the front end of the first non-tail portion 248 and the second tail portion 257 are arranged opposite to each other in the thickness direction of the positive electrode 211.

[0042] When the flux layer expands and contracts during charging and discharging, the exposed core portion formed in the middle of the electrode's length direction is prone to the same stress as the flux layer forming portion. If the difference in rigidity between the flux layer forming portion and the exposed core portion increases, deformation such as wrinkles is more likely to occur in the core at the boundary between the flux layer forming portion and the exposed core portion. Therefore, compared to the boundary between the tail portion and the exposed core portion, deformation such as wrinkles is more likely to occur in the core at the boundary between the non-tail portion and the exposed core portion. In the battery 10 of the above embodiment, the front ends of the non-tail portions 48, 58 are arranged opposite to the flat portions 42c, 42d of the positive electrode flux layer 42 adjacent to the tail portions 47, 57 in the thickness direction of the positive electrode 11. As a result, since the change in rigidity from the non-tail portions 48, 58 to the exposed core portions 41a, 41b is alleviated, deformation of the positive electrode core 41 at the boundary between the non-tail portions 48, 58 and the exposed core portions 41a, 41b can be suppressed. On the other hand, in the battery 210 of the reference example, since the front ends of the non-tailed portions 248 and 258 of the positive electrode compound layer 242 are arranged opposite to the tailed portions 247 and 257 whose rigidity is less than that of the flat portion, the effect of mitigating the rigidity difference from the non-tailed portions 248 and 258 to the exposed core portions 241a and 241b is insufficient, and the deformation of the positive electrode core 241 cannot be sufficiently suppressed.

[0043] Furthermore, since the leading edges of the non-tailed portions 48 and 58 and the flat portions 42c and 42d of the positive electrode mixture layer 42 adjacent to the tailed portions 47 and 57 are arranged opposite each other in the thickness direction of the positive electrode 11, the length of the roll descending in the thickness direction at the aforementioned boundary portion is reduced when the positive electrode mixture slurry film is compressed by the roller after drying. As a result, the impact on the positive electrode 11 due to the descent of the roller is reduced, and therefore, the deformation of the boundary portion of the positive electrode core 41 is also suppressed.

[0044] When a portion of the positive electrode compound layer 42 is arranged adjacent to the core exposed portions 41a and 41b in the width direction, the range of rigidity difference from the non-tailed portions 48 and 58 to the core exposed portions 41a and 41b is reduced. Therefore, the effect of deformation suppression at the boundary between the positive electrode core 41 and the positive electrode compound layer 42 of the present invention becomes significant.

[0045] Furthermore, when a portion of the positive electrode compound layer 42 is arranged adjacent to the core exposed portions 41a and 41b in the width direction, the descent length of the roller at the boundary portion in the width direction of the positive electrode 11 is further reduced. As a result, the impact on the positive electrode 11 due to the descent of the roller is further reduced, and thus the deformation of the boundary portion of the positive electrode core 41 is further suppressed.

[0046] To suppress the peeling of the positive electrode compound layer 42 from the positive electrode core 41, it is preferable to arrange a trailing portion 57 adjacent to the end of the core exposed portion 41a on the winding start side of the outer winding surface 51 of the positive electrode 11. This is because the trailing portion 57 is more difficult to peel off from the positive electrode core 41 compared to the non-trailing portion 58.

[0047] This invention is not limited to the above-described embodiments and their variations, and various improvements and modifications can be made to the matters described in the scope of protection claimed in this application and their equivalents.

[0048] Figure 5 is a top view of the modified battery 110 corresponding to Figure 2. As shown in Figure 5, a first core exposed portion 141a can be provided on the outer surface 151 of the first surface, which serves as the positive electrode 111, from one end to the other in the width direction of the positive electrode 111. At this time, the trailing portion 147 and the non-trailing portion 148 are also provided from one end to the other in the width direction of the positive electrode 111. The positive electrode lead 120 is joined to the first core exposed portion 141a. In this case, on the second surface of the positive electrode 111, at least a portion of a second core exposed portion (not shown) is disposed opposite to the first core exposed portion 141a in the thickness direction of the positive electrode 111, which can also be provided from one end to the other in the width direction of the positive electrode 111. It should be noted that in Figure 5, the outer edge of the insulating tape 161a covering the positive electrode lead 120 and the first core exposed portion 141a is represented by a dashed line. In addition, the cross section at line A′-A′ in Figure 5 is the same as the cross section shown in Figure 3.

[0049] The first core exposed portion of the positive electrode lead can also be located on the inner surface of the positive electrode winding. In addition, in this case, in order to suppress the peeling of the positive electrode adhesive layer, it is preferable that the non-tail portion is located on the winding start side of the first core exposed portion on the inner surface of the positive electrode winding.

[0050] In the negative electrode, the leading edge of the second non-tailed portion may be arranged opposite to the first flat portion of the first adhesive layer adjacent to the first tailed portion in the thickness direction of the negative electrode, and the leading edge of the first non-tailed portion may be arranged opposite to the second flat portion of the second adhesive layer adjacent to the second tailed portion in the thickness direction of the negative electrode. In this case, a negative electrode lead, as an example of an electrode lead, is joined at the exposed portion of the first core.

[0051] The electrode of this invention can be applied to both the positive and negative electrodes.

[0052] In addition, the secondary battery of the present invention can be configured as follows.

[0053] Configuration 1: A secondary battery comprising an electrode body formed by winding two electrodes of different polarities together along a length direction with a spacer between them. One electrode has a first exposed core portion on its first surface, which is configured to be held along the length direction by a first adhesive layer disposed on the first surface and simultaneously joined with electrode leads. The second surface of the electrode has a second exposed core portion, which is also configured to be held along the length direction by a second adhesive layer disposed on the second surface and at least a portion of which is disposed opposite to the first exposed core portion in the thickness direction. The first adhesive layer has a first trailing portion and a first non-trailing portion. The first trailing portion is adjacent to the first end of the first exposed core portion along the length direction and has a plurality of first trailing portions extending along the length direction. The first non-trailing portions are adjacent to the first exposed core portion. The second compound layer has a second non-tail portion and a second tail portion. The second non-tail portion is adjacent to the end of the second core exposed portion on the first side of the length direction, while its front end extends in the generally width direction. The second tail portion is adjacent to the end of the second core exposed portion on the second side of the length direction, while its front end extends in the generally width direction. The second tail portion is adjacent to the end of the second core exposed portion on the second side of the length direction, while having a plurality of second tails extending in the length direction. The front end of the second non-tail portion is disposed opposite to the first flat portion of the first compound layer in the thickness direction. The first flat portion of the first compound layer is adjacent to the first tail portion. The front end of the first non-tail portion is disposed opposite to the second flat portion of the second compound layer in the thickness direction. The second flat portion of the second compound layer is adjacent to the second tail portion.

[0054] Configuration 2: The secondary battery described in Configuration 1, wherein one of the electrodes is the positive electrode.

[0055] Configuration 3: The secondary battery described in Configuration 1, wherein one of the electrodes is the negative electrode.

[0056] Configuration 4: A secondary battery according to any one of configurations 1 to 3, wherein a portion of the first compound layer is disposed adjacent to the first exposed core portion in the width direction, and a portion of the second compound layer is disposed adjacent to the second exposed core portion in the width direction.

[0057] Configuration 5: A secondary battery according to any one of configurations 1 to 4, wherein the first surface is the outer surface of the winding, and the first side in the length direction is the winding start side of the one electrode.

[0058] Configuration 6: A secondary battery according to any one of configurations 1 to 4, wherein the first surface is the inner surface of the winding, and the first side in the length direction is the winding end side of the one electrode.

[0059] Explanation of reference numerals in the attached figures

[0060] 10, 110 Battery; 11, 111 Positive electrode; 12 Negative electrode; 13 Spacer; 14 Electrode body; 16 Outer packaging can; 17 Sealing body; 18, 19 Insulating plate; 20, 120 Positive electrode lead; 21 Negative electrode lead; 23 Terminal plate; 23a Through hole; 24 Lower valve body; 25 Insulating component; 26 Upper valve body; 27 Terminal cap; 27a Through hole; 28 Gasket; 30 Cylindrical part; 34 Slotted part; 35 Peripheral part; 38 Shoulder; 41 Positive electrode core; 41a, 141a First core exposed part; 41b Second core exposed part; 42 Positive electrode binder layer; 42a First binder layer; 42b Second binder layer; 42c First flat part; 42d Second flat part; 47 First trailing part; 47a 1st trailing portion, 48 1st non-trailing portion, 51, 151 outer surface winding, 52 inner surface winding, 57 2nd trailing portion, 57a 2nd trailing portion, 58 2nd non-trailing portion, 61a, 61b, 161a insulating tape, 68 bottom, 74 boundary portion, 147 trailing portion, 148 non-trailing portion.

Claims

1. A secondary battery comprising an electrode body formed by winding two electrodes of different polarities together along a length direction with a spacer between them, wherein a first surface of one of the electrodes has a first exposed core portion, the first exposed core portion being configured to be held along the length direction by a first adhesive layer disposed on the first surface and simultaneously joined with an electrode lead, and a second surface of the electrode having a second exposed core portion, the second exposed core portion being configured to be held along the length direction by a second adhesive layer disposed on the second surface and simultaneously at least a portion being disposed opposite to the first exposed core portion in the thickness direction, the first adhesive layer having a first trailing portion and a first non-trailing portion, the first trailing portion being adjacent to the end of the first exposed core portion on a first side along the length direction and having a plurality of first trailing portions extending along the length direction, the first non-trailing portion being adjacent to the first exposed core portion. The second compound layer has a second non-trailing portion and a second trailing portion. The second non-trailing portion is adjacent to the end of the second core exposed portion on the first side of the length direction while its front end extends in the approximate width direction. The second trailing portion is adjacent to the end of the second core exposed portion on the second side of the length direction while having a plurality of second trailing portions extending in the length direction. The front end of the second non-trailing portion is disposed opposite to the first flat portion of the first compound layer in the thickness direction. The first flat portion of the first compound layer is adjacent to the first trailing portion. The front end of the first non-trailing portion is disposed opposite to the second flat portion of the second compound layer in the thickness direction. The second flat portion of the second compound layer is adjacent to the second trailing portion.

2. The secondary battery according to claim 1, wherein, One of the electrodes is the positive electrode.

3. The secondary battery according to claim 1, wherein, One of the electrodes is the negative electrode.

4. The secondary battery according to any one of claims 1 to 3, wherein, A portion of the first compound layer is disposed adjacent to the exposed portion of the first core in the width direction, and a portion of the second compound layer is disposed adjacent to the exposed portion of the second core in the width direction.

5. The secondary battery according to any one of claims 1 to 3, wherein, The first surface is the outer surface of the winding, and the first side in the length direction is the winding start side of the electrode.

6. The secondary battery according to any one of claims 1 to 3, wherein, The first surface is the inner surface of the winding, and the first side in the length direction is the winding end side of the electrode.

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