Tablet battery

Abstract

The electrode winding comprises a positive electrode, a negative electrode, and a separator between the positive and negative electrodes. The positive electrode has a positive electrode foil extension extending from the positive electrode foil. The negative electrode has a negative electrode foil extension extending from the negative electrode foil. The positive electrode, negative electrode, and separator are wound in a spiral shape with through holes, and the central axis passes through the through holes. The positive electrode foil extension and the negative electrode foil extension extend from opposite ends of the electrode winding. A portion of the positive electrode foil extension includes a bent portion that folds toward the central axis so as to define a first surface by overlapping portions of the positive electrode foil extension. A portion of the negative electrode foil extension includes a bent portion that folds toward the central axis so as to define a second surface by overlapping portions of the negative electrode foil extension.

Description

Display of Related Applications

[0001] This application claims priority to U.S. Patent Application No. 63 / 456,111, filed on March 31, 2023, the content of which is incorporated herein by reference.

Background Art

[0002] 1. Technical Field The present invention relates to batteries. More specifically, the present invention relates to a rechargeable tabless battery.

[0003] 2. Description of Related Art Lithium-ion batteries have also been developed for applications that require high power, such as power tools and electric vehicles. One way to achieve high power is high-rate discharge, in which a relatively large current flows from the battery. Since high-rate discharge involves flowing a large current, the internal resistance of the battery has become a problem.

[0004] For example, in conventional battery technology, in order to collect current from the entire end of the wound foil, the welding points are concentrated toward the center, so simply folding and overlapping the foils results in a region with less overlap of the foils on the center side of the electrode assembly, and there is a problem that holes are formed during welding. Also, when welding the bottom of the can during the assembly process, sufficient space is required at the center of the electrode assembly, but when folding the foil from the outer peripheral edge toward the center, the space at the center formed during winding is blocked, and there is also a problem that assembly cannot be performed.

Summary of the Invention

[0005] To solve the above problems, exemplary embodiments of the present invention include bent portions in the positive electrode foil and the negative electrode foil, and provide a battery that can achieve high-rate discharge and can be reliably welded. <​An exemplary electrode winding according to one embodiment of the present invention comprises a positive electrode, a negative electrode, and a separator between the positive and negative electrodes. The positive electrode has a positive electrode foil, a positive electrode active material provided on a portion of the positive electrode foil, and a positive electrode foil extension extending from the positive electrode foil. The positive electrode active material is not provided on the positive electrode foil extension. The negative electrode has a negative electrode foil, a negative electrode active material provided on a portion of the negative electrode foil, and a negative electrode foil extension extending from the negative electrode foil. The negative electrode active material is not provided on the negative electrode foil extension. The positive electrode, negative electrode, and separator are wound in a spiral shape with through holes, and the central axis passes through the through holes. The positive electrode foil extension extends from a first end of the electrode winding. The negative electrode foil extension extends from a second end opposite to the first end of the electrode winding. A portion of the positive electrode foil extension includes a first bend that is bent toward the central axis so as to define a first surface by overlapping with a portion of the positive electrode foil extension. The positive electrode foil extension has a first groove on its first surface. A portion of the negative electrode foil extension includes a second bend that is bent toward the central axis so as to define a second surface by overlapping with a portion of the negative electrode foil extension. The negative electrode foil extension has a second groove on its second surface.

[0007] The bottom surface of the first groove may be curved, and the bottom surface of the second groove may also be curved. The first curvature of the first groove may be smaller than the second curvature of the second groove.

[0008] The second groove may be deeper than the first groove. The first and second grooves may each have a rectangular cross-section. Part of the separator may include a third bend. Part of the positive electrode active material may include a fourth bend, and part of the negative electrode active material may include a fifth bend. Part of the positive electrode foil and / or part of the negative electrode foil may be folded over the innermost portion of the separator closest to the through hole.

[0009] A portion of the positive electrode foil extension may include a plurality of first bends, and a portion of the negative electrode foil extension may include a plurality of second bends, and the number of the plurality of first bends in the positive electrode foil extension may be greater than the number of the plurality of second bends in the negative electrode foil extension. The first bend shape of the first bend in the positive electrode foil extension may be asymmetrical with respect to the central axis, and the second bend shape of the second bend in the negative electrode foil extension may be asymmetrical with respect to the central axis. The electrode winding may further include gaps between radially adjacent first bends in the positive electrode foil extension or between radially adjacent second bends in the negative electrode foil extension.

[0010] The first surface may be substantially smooth and have a glossy appearance, and the second surface may be substantially smooth and have a glossy appearance.

[0011] The first distance between adjacent radial portions of the positive electrode foil extension may decrease as the second distance to the negative electrode active material increases, and the third distance between adjacent radial portions of the negative electrode foil extension may decrease as the fourth distance from the positive electrode active material increases.

[0012] The first distance between adjacent radial portions of the positive electrode foil extension may decrease as the second distance to the through hole decreases, and the third distance between adjacent radial portions of the negative electrode foil extension may decrease as the fourth distance to the through hole decreases.

[0013] The degree of fit between radially adjacent portions of the positive electrode foil extension may increase as the first distance to the through hole decreases, and the degree of fit between radially adjacent portions of the negative electrode foil extension may increase as the second distance to the through hole decreases.

[0014] An exemplary embodiment of the present invention is a battery comprising an outer casing and an electrode winding provided inside the outer casing, which relates to any one of the other exemplary embodiments of the present invention.

[0015] The battery may further include a positive electrode current collector plate bonded to a first surface and including a flat first fan-shaped portion and a rectangular first strip-shaped portion, and a negative electrode current collector plate bonded to a second surface and including a flat second fan-shaped portion and a rectangular second strip-shaped portion.

[0016] After the positive electrode current collector plate is joined to the first surface and the negative electrode current collector plate is joined to the second surface, the first groove does not need to maintain its cross-sectional shape, while the second groove may maintain its cross-sectional shape.

[0017] The first fan-shaped portion of the positive electrode current collector plate includes a first curved portion and two first straight portions, and the two first lines of the two first straight portions may be on the same straight line. The second fan-shaped portion of the negative electrode current collector plate includes a second curved portion and two second straight portions, and the two second lines of the two second straight portions may be on the same straight line.

[0018] The flat first fan-shaped portion and the rectangular first strip portion of the positive electrode current collector plate may be connected by two curved first corners, and the flat second fan-shaped portion and the rectangular second strip portion of the negative electrode current collector plate may be connected by two curved second corners.

[0019] The battery may further include a positive electrode insulator bonded to a positive electrode current collector plate, having a relatively large hole aligned with the through hole, and having a plurality of relatively small holes arranged around the relatively large hole, and a negative electrode insulator bonded to a negative electrode current collector plate, having a hole aligned with the through hole.

[0020] An exemplary electrode winding according to one embodiment of the present invention comprises a positive electrode, a negative electrode, and a separator between the positive and negative electrodes. The positive electrode has a positive electrode foil, a positive electrode active material provided on a portion of the positive electrode foil, and a positive electrode foil extension extending from the positive electrode foil. The positive electrode active material is not provided on the positive electrode foil extension. The negative electrode has a negative electrode foil, a negative electrode active material provided on a portion of the negative electrode foil, and a negative electrode foil extension extending from the negative electrode foil. The negative electrode active material is not provided on the negative electrode foil extension. The positive electrode, negative electrode, and separator are wound in a spiral shape with through holes, and the central axis passes through the through holes. The positive electrode foil extension extends from a first end of the electrode winding. The negative electrode foil extension extends from a second end opposite to the first end of the electrode winding. A portion of the positive electrode foil extension includes a first bend that is bent toward the central axis so as to define a first surface by overlapping portions of the positive electrode foil extension. The first bend shape of the first bend of the positive electrode foil extension may be asymmetrical with respect to the central axis. A portion of the negative electrode foil extension includes a second bend that is bent toward the central axis so as to define a second surface by overlapping portions of the negative electrode foil extension. The second bend shape of the second bend of the negative electrode foil extension may be asymmetrical with respect to the central axis.

[0021] A portion of the positive electrode foil extension may include a plurality of first bends, and a portion of the negative electrode foil extension may include a plurality of second bends, and the number of plurality of first bends in the positive electrode foil extension may be greater than the number of plurality of second bends in the negative electrode foil extension. A portion of the separator may include a third bend. A portion of the positive electrode active material may include a fourth bend, and a portion of the negative electrode active material may include a fifth bend. A portion of the positive electrode foil and / or a portion of the negative electrode foil may be folded over the innermost portion of the separator closest to the through hole.

[0022] The positive electrode foil extension has a first groove on its first surface, and the negative electrode foil extension has a second groove on its second surface. The bottom surface of the first groove may be curved, and the bottom surface of the second groove may also be curved. The first curvature of the first groove may be smaller than the second curvature of the second groove. The second groove may be deeper than the first groove. The first groove and the second groove may each have a rectangular cross-section.

[0023] The electrode winding body may further include a gap between the first bending portions adjacent to each other in the radial direction of the positive electrode foil extension portion or between the second bending portions adjacent to each other in the radial direction of the negative electrode foil extension portion.

[0024] The first surface may be a substantially smooth surface and have a shiny appearance, and the second surface may be a substantially smooth surface and have a shiny appearance.

[0025] The first distance between the portions adjacent to each other in the radial direction of the positive electrode foil extension portion may become shorter as the second distance to the negative electrode active material becomes longer, and the third distance between the portions adjacent to each other in the radial direction of the negative electrode foil extension portion may become shorter as the fourth distance from the positive electrode active material becomes longer.

[0026] The first distance between the portions adjacent to each other in the radial direction of the positive electrode foil extension portion may become shorter as the second distance to the through hole becomes shorter, and the third distance between the portions adjacent to each other in the radial direction of the negative electrode foil extension portion may become shorter as the fourth distance to the through hole becomes shorter.

[0027] The fitting degree of the portions adjacent to each other in the radial direction of the positive electrode foil extension portion may become higher as the first distance to the through hole becomes shorter, and the fitting degree of the portions adjacent to each other in the radial direction of the negative electrode foil extension portion may become higher as the second distance to the through hole becomes shorter.

[0028] The battery according to an exemplary embodiment of the present invention includes an outer can and an electrode winding body according to any one of the other exemplary embodiments of the present invention provided inside the outer can.

[0029] The battery may further include a positive electrode current collector plate joined to the first surface and including a flat first fan-shaped portion and a rectangular first strip portion, and a negative electrode current collector plate joined to the second surface and including a flat second fan-shaped portion and a rectangular second strip portion.

[0030] After the positive electrode current collector plate is joined to the first surface and the negative electrode current collector plate is joined to the second surface, the first groove may not maintain its cross-sectional shape, and the second groove may maintain its cross-sectional shape.

[0031] The first fan-shaped portion of the positive electrode current collector plate includes a first curved portion and two first straight portions, and the two first lines of the two first straight portions may be on the same straight line. The second fan-shaped portion of the negative electrode current collector plate includes a second curved portion and two second straight portions, and the two second lines of the two second straight portions may be on the same straight line.

[0032] The flat first fan-shaped portion and the rectangular first strip portion of the positive electrode current collector plate may be connected by two curved first corners, and the flat second fan-shaped portion and the rectangular second strip portion of the negative electrode current collector plate may be connected by two curved second corners.

[0033] The battery may further include a positive electrode insulator bonded to a positive electrode current collector plate, having a relatively large hole aligned with the through hole, and having a plurality of relatively small holes arranged around the relatively large hole, and a negative electrode insulator bonded to a negative electrode current collector plate, having a hole aligned with the through hole.

[0034] The above and other features, elements, properties, processes, and advantages of the present invention will become more apparent from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. [Brief explanation of the drawing]

[0035] The patent or application documents include at least one drawing made in color. A copy of the published version of this patent or patent application, including the color drawing, will be provided by the Patent Office upon request and payment of the required fees.

[0036] Figure 1 is a schematic diagram showing a cross-section of a battery.

[0037] Figure 2 is a schematic diagram illustrating an example of the relationship between the positive electrode, negative electrode, and separator in an electrode winding.

[0038] Figure 3A is a schematic plan view of the positive electrode current collector plate.

[0039] Figure 3B is a schematic plan view of the negative electrode current collector plate.

[0040] Figures 4A to 4F are schematic diagrams illustrating the battery assembly process.

[0041] Figure 5A is a schematic diagram representing the negative electrode side of a battery, showing the lines of the various cross-sections shown in Figures 6A to 9D.

[0042] Figure 5B is a photograph corresponding to Figure 5A, which shows the negative electrode side of the battery, illustrating the lines of the various cross-sections shown in Figures 6A to 9D.

[0043] Figure 6A is a schematic diagram showing a cross-section of the positive electrode side of the battery, along the groove of the positive electrode foil extension.

[0044] Figure 6B is a schematic diagram showing a cross-section of the negative electrode side of the battery along the groove of the negative electrode foil extension.

[0045] Figure 6C is a photograph corresponding to Figure 6A, showing a cross-section of the positive electrode side of the battery along the groove of the positive electrode foil extension.

[0046] Figure 6D is a photograph corresponding to Figure 6B, showing a cross-section of the negative electrode side of the battery along the groove of the negative electrode foil extension.

[0047] Figure 7A is a schematic diagram showing a partially enlarged view of Figure 6A.

[0048] Figures 7B to 7D are traced images that are partial enlargements of a photograph in Figure 7A.

[0049] Figure 7E is a schematic diagram that is a partial enlargement of Figure 6B.

[0050] Figures 7F to 7H are traced diagrams that are partial enlargements of a photograph from Figure 7E.

[0051] Figure 7I is a photograph corresponding to Figure 7A.

[0052] Figure 7J is a photograph corresponding to Figure 7E.

[0053] Figure 8A is a schematic diagram showing a cross-section of the positive electrode side of a battery, including the positive electrode foil extension but not along the groove of the positive electrode foil extension.

[0054] Figures 8B to 8D are traced images that are partial enlargements of a photograph in Figure 8A.

[0055] Figure 8E is a schematic diagram showing a cross-section of the negative electrode side of the battery, including the negative electrode foil extension but not along the groove of the negative electrode foil extension.

[0056] Figures 8F to 8H are traced diagrams of partially enlarged portions of the photograph in Figure 8E.

[0057] Figure 8I is a photograph corresponding to Figure 8A.

[0058] Figure 8J is a photograph corresponding to Figure 8E.

[0059] Figure 9A is a schematic diagram showing a cross-section of the positive electrode side of the battery, crossing the weld line that joins the positive electrode foil extension and the positive electrode current collector plate, as well as crossing multiple grooves in the positive electrode foil extension.

[0060] Figure 9B is a schematic diagram showing a cross-section of the negative electrode side of the battery, crossing the weld line that joins the negative electrode foil extension and the negative electrode current collector plate, as well as crossing multiple grooves in the negative electrode foil extension.

[0061] Figure 9C is a photograph corresponding to Figure 9A.

[0062] Figure 9D is a photograph corresponding to Figure 9B.

[0063] Figure 10A is a schematic diagram showing the positive electrode end of a battery, including the positive electrode foil extension.

[0064] Figure 10B is a photograph corresponding to Figure 10A.

[0065] Figure 11A is a schematic diagram showing the negative electrode end of a battery, including the negative electrode foil extension.

[0066] Figure 11B is a photograph corresponding to Figure 11A.

[0067] Figure 12A is a schematic diagram representing the positive electrode end of a battery, showing the weld line on the positive electrode current collector plate.

[0068] Figure 12B is a schematic diagram representing the negative electrode end of a battery, showing the weld lines in the positive and negative electrode current collector plates.

[0069] Figure 12C is a schematic diagram showing a partially enlarged view of the weld line in the positive electrode current collector plate in Figure 12A.

[0070] Figure 12D is a schematic cross-sectional view showing the weld line in the positive electrode current collector plate of Figure 12A.

[0071] Figures 12E to 12H are photographs corresponding to Figures 12A to 12D.

[0072] Figure 13A is a schematic diagram showing the insulators at both ends of the electrode winding.

[0073] Figures 13B and 13C are schematic diagrams representing the insulator at the positive electrode end of the electrode winding.

[0074] Figures 13D and 13E are schematic diagrams representing the insulator at the negative electrode end of the electrode winding.

[0075] Figures 13F to 13I are photographs corresponding to Figures 13B to 13E.

[0076] Figure 14A is a schematic diagram showing the positive electrode insulating plate and the negative electrode insulating plate at each end of the electrode winding.

[0077] Figures 14B and 14C are schematic diagrams representing the positive electrode insulating plate at the positive electrode end of the electrode winding.

[0078] Figures 14D and 14E are schematic diagrams representing the negative electrode insulating plate at the negative electrode end of the electrode winding.

[0079] Figures 14F to 14I are photographs corresponding to Figures 14B to 14E.

[0080] Figure 15A is a schematic diagram representing the positive electrode current collector at the positive electrode end of the electrode winding.

[0081] Figure 15B is a schematic diagram representing the negative electrode current collector at the negative electrode end of the electrode winding.

[0082] Figures 15C and 15D are photographs corresponding to Figures 15A and 15B. Detailed description of exemplary embodiments

[0083] Figure 1 is a schematic cross-sectional view of battery 1. Figures 5A to 13I include schematic diagrams and photographs of batteries corresponding to battery 1 in Figure 1.

[0084] Battery 1 may be a rechargeable battery, for example, a cylindrical lithium-ion battery. Other types of batteries, or batteries with shapes other than cylindrical, can also be used.

[0085] As shown in Figure 1, the battery 1 may include an electrode winding 20 housed inside the outer casing 11. Specifically, the battery 1 may include, for example, a pair of insulating plates 12 and 13 and the electrode winding 20 inside a cylindrical outer casing 11. The battery 1 may further include, for example, one or more of the following inside the outer casing 11: a positive temperature coefficient (PTC) element and reinforcing members.

[0086] The outer container 11 houses the electrode winding 20. The outer container 11 can be a cylindrical container having an open end and a closed end. That is, the outer container 11 may have an open end 11N. The outer container 11 may contain one or more types of metallic materials, such as iron, aluminum, and their alloys. The surface of the outer container 11 may be plated with one or more types of metallic materials, such as nickel.

[0087] Each of the insulating plates 12 and 13 can be, for example, a dish-shaped plate having a surface perpendicular or substantially perpendicular to the winding axis of the electrode winding body 20 within the manufacturing tolerance and / or measurement tolerance, i.e., a surface perpendicular or substantially perpendicular to the Z-axis in Figure 1 within the manufacturing tolerance and / or measurement tolerance. The insulating plates 12 and 13 may also be provided so as to sandwich the electrode winding body 20.

[0088] The open end 11N of the outer casing 11 may have a battery cover 14 and a safety valve 30 crimped to it via a gasket 15, for example. The battery cover 14 functions as a "cover member," and the gasket 15 functions as a "sealing member." As a result, the outer casing 11 is sealed when the electrode winding body 20 and the like are housed inside it. Therefore, a crimped structure (crimped structure 11R) is formed at the open end 11N of the outer casing 11 by crimping the battery cover 14 and the safety valve 30 via the gasket 15. More specifically, the bent portion 11P is a so-called crimped portion, and the crimped structure 11R is a so-called crimped structure.

[0089] The battery cover 14 primarily closes the open end 11N of the outer casing 11 when the electrode winding 20 and the like are housed inside the outer casing 11. The battery cover 14 may contain, for example, the same material as the forming material of the outer casing 11. The central region of the battery cover 14 protrudes in the +Z direction, for example. As a result, the region of the battery cover 14 other than the central region (peripheral region) is in contact with, for example, the safety valve 30.

[0090] The gasket 15 primarily seals the gap between the folded portion 11P and the battery cover 14 by being interposed between the outer can 11 (folded portion 11P) and the battery cover 14. However, the surface of the gasket 15 may be coated with, for example, asphalt.

[0091] The gasket 15 includes, for example, one or more types of insulating materials. The type of insulating material is not particularly limited, but can be, for example, a polymer material such as polybutylene terephthalate (PBT) and polypropylene (PP). In particular, the insulating material may be polybutylene terephthalate. This is because it electrically separates the outer casing 11 and the battery cover 14 from each other while adequately sealing the gap between the folded portion 11P and the battery cover 14.

[0092] The safety valve 30 primarily releases the internal pressure inside the outer can 11 by releasing the sealed state of the outer can 11 as needed when the internal pressure rises. The cause of the rise in internal pressure inside the outer can 11 is, for example, gas generated due to the decomposition reaction of the electrolyte during charging and discharging.

[0093] In battery 1, a strip-shaped positive electrode 21 and a strip-shaped negative electrode 22 are wound in a spiral shape via a separator 23 and housed in an outer casing 11 while impregnated with an electrolyte. The positive electrode 21 may be a positive electrode foil 21A with a positive electrode active material layer 21B formed on one side or part of both sides. Examples of materials for the positive electrode foil 21A include metal foil made of aluminum or an aluminum alloy. For example, the positive electrode 21 can be an aluminum foil with a thickness of about 12 μm within the manufacturing tolerance and / or measurement tolerance. The negative electrode 22 may be a negative electrode foil 22A with a negative electrode active material layer 22B formed on one side or part of both sides. Examples of materials for the negative electrode foil 22A include metal foil made of nickel, a nickel alloy, copper or a copper alloy. For example, the negative electrode 22 can be a copper foil with a thickness of about 8 μm within the manufacturing tolerance and / or measurement tolerance. The separator 23 may include an insulating porous membrane, which electrically insulates the positive electrode 21 and the negative electrode 22 while allowing the movement of substances such as ions and electrolytes.

[0094] The positive electrode active material layer 21B and the negative electrode active material layer 22B each cover many parts of the positive electrode foil 21A and the negative electrode foil 22A, but intentionally, neither covers the periphery of one end in the short axis direction of the strip. Among the positive electrode foil 21 or the negative electrode foil 22, a portion that extends from the positive electrode foil 21 or the negative electrode foil 22 but is not covered by the positive electrode active material layer 21B or the negative electrode active material layer 22B is referred to as the positive electrode foil extension portion 21c or the negative electrode foil extension portion 22c. In the battery 1, the electrode winding body 20 is wound so as to define a through hole 26 having a central axis.

[0095] FIG. 2 shows an example of the structure before winding in which the positive electrode 21, the negative electrode 22, and the separator 23 are laminated. Let the width of the positive electrode foil extension portion 21C (the upper slanted portion in FIG. 2) of the positive electrode 21 be A, and the width of the negative electrode foil extension portion 22C (the lower slanted portion in FIG. 2) of the negative electrode 22 be B. A > B may be satisfied. For example, A = 7 (mm) and B = 4 (mm), but other dimensions may also be used. Let the length of the portion where the positive electrode foil extension portion 21C of the positive electrode 21 protrudes from one end in the width direction of the separator 23 be C, and the length of the portion where the negative electrode foil extension portion 22C of the negative electrode 22 protrudes from the other end in the width direction of the separator 23 be D. C > D may be satisfied. For example, C = 4.5 (mm) and D = 3 (mm), but other dimensions may also be used. The width of the complete laminate in which the positive electrode 21, the negative electrode 22, and the separator 23 overlap can be designated as G. The length of the positive electrode foil extension portion 21C extending from the complete laminate can be designated as E, and the length of the negative electrode foil extension portion 22C extending from the complete laminate can be designated as F. E < F may be satisfied. For example, E = 3.5 (mm) and F = 4.5 (mm), but other dimensions may also be used.

[0096] The positive electrode foil extension 21C of the positive electrode 21 can be made of aluminum, for example, and the negative electrode foil extension 22C of the negative electrode 22 can be made of copper, for example. Generally, the positive electrode foil extension 21C of the positive electrode 21 is softer (has a lower Young's modulus) than the negative electrode foil extension 22C of the negative electrode 22. For this reason, even if A>B and C>D are satisfied, when the positive electrode foil extension 21C of the positive electrode 21 and the negative electrode foil extension 22C of the negative electrode 22 are bent simultaneously from both electrode sides with the same pressure, the height measured from the tip of the separator 23 at the bent portion may be about the same for both the positive electrode 21 and the negative electrode 22. By bending the positive electrode foil extension 21C so that the bent portions of radially adjacent parts of the positive electrode foil extension 21C overlap, it is possible to easily join the positive electrode foil extension 21C to the current collector plate 24. By bending the negative electrode foil extension 22C so that the radially adjacent bent portions of the negative electrode foil extension 21C overlap, the negative electrode foil extension 22C and the current collector plate 25 can be easily joined. "Joining" may mean joining by laser welding, but the joining method is not limited to laser welding. The shapes of the different bent portions of the positive electrode foil extension 21C may be different, and the shapes of the different bent portions of the negative electrode foil extension 22C may be different. For example, the shape of the bent portion of the positive electrode foil extension 21C can be asymmetrical with respect to the central axis passing through the through hole 26, and the shape of the bent portion of the negative electrode foil extension 22C can be asymmetrical with respect to the central axis passing through the through hole 26. When the positive electrode foil extension 21C and the negative electrode foil extension 22C are bent, the separator 23 may also be bent. Furthermore, if the positive electrode foil extension 21C and the negative electrode foil extension 22C are bent, the positive electrode active material layer 21B and / or the negative electrode active material layer 22B may also be bent.

[0097] The positive electrode 21 is covered with an insulating layer 101 (gray area in Figure 2) over a section approximately 3 mm wide, within the manufacturing tolerance and / or measurement tolerance, including the boundary between the positive electrode foil extension 21C and the positive electrode active material layer 21B. The entire area of ​​the positive electrode foil extension 21C of the positive electrode 21 facing the negative electrode active material layer 22B of the negative electrode 22 via the separator 23 is covered with the insulating layer 101. The insulating layer 101 effectively prevents internal short circuits in the battery 1 when foreign matter enters between the negative electrode active material layer 22B of the negative electrode 22 and the positive electrode foil extension 21C of the positive electrode 21. Furthermore, the insulating layer 101 absorbs shocks when the battery 1 is subjected to impact, effectively preventing bending of the positive electrode foil extension 21C of the positive electrode 21 and short circuits with the negative electrode 22.

[0098] The central axis of the electrode winding body 20 passes through the through hole 26. The through hole 26 is a hole into which the winding core and the electrode rod for welding are inserted. The electrode winding body 20 is wound with the positive electrode foil extension 21C of the positive electrode 21 and the negative electrode foil extension 22C of the negative electrode 22 overlapping so that they extend in opposite directions from the electrode winding body 20. Therefore, the positive electrode foil extension 21C of the positive electrode 21 is located at end 41 of the electrode winding body 20, and the negative electrode foil extension 22C of the negative electrode 22 is located at end 42 of the electrode winding body 20. In order to improve contact with the current collector plates 24 and 25 for extracting current, the positive electrode foil extension 21C and the negative electrode foil extension 22C may be bent so that the ends 41 and 42 become substantially flat surfaces within the manufacturing tolerance. The bending direction is from the outer edges 27, 28 of the ends 41, 42 toward the through hole 26, and when wound, the positive electrode foil extensions 21C or negative electrode foil extensions 22C of adjacent circumferences overlap and bend, defining a substantially smooth surface within the manufacturing tolerances that has a glossy appearance. The specular gloss Gs(60°) of a substantially smooth surface can be measured in accordance with JIS Z 8741:1997 with an incident light angle of 60°. For example, the specular gloss Gs(60°) value for a glass surface with a refractive index of 1.567 is 100. The surface may be substantially flat or may have one or more raised parts. In any case, the surface may have some irregularities, but it may be substantially smooth enough that it does not affect the joint with the current collector plate 24 or 25.

[0099] By folding the positive electrode foil extension 21C so that the bent portions of a part of the positive electrode foil extension 21C overlap, it is possible to make the end portion 41 a flat surface. By folding the negative electrode foil extension 22C so that the bent portions of a part of the negative electrode foil extension 22C overlap, it is possible to make the end portion 42 a flat surface. By folding the positive electrode foil extension 21C and the negative electrode foil extension 22C, bends, folds, wrinkles, voids, or gaps may occur at the ends 41 and 42. For example, Figures 7B and 7H show the gaps 44 between the folds of the positive electrode foil extension 21C and the negative electrode foil extension 22C that are bent in opposite directions. For example, if the positive electrode foil 21A is softer than the negative electrode foil 22A (i.e., has a lower Young's modulus), and / or if the length of the positive electrode foil extension 21C from the complete laminate is shorter than the length of the negative electrode foil extension 22C from the complete laminate, the number of bends, folds, or wrinkles in the positive electrode foil 21A may be greater than the number of bends, folds, or wrinkles in the negative electrode foil 22A.

[0100] A groove 43 (see, for example, Figure 4B) may be formed radially in the electrode winding body 20 with the through hole 26 as the center. The groove 43 may extend from the outer edges 27, 28 of the ends 41, 42 to the through hole 26. The central axis of the electrode winding body 20 passes through the through hole 26, and the through hole 26 is used as a hole for inserting a welding tool during the assembly process of the battery 1. If the groove is formed on the flat surface before the positive electrode foil extension 21C and the negative electrode foil extension 22C are bent, the groove 43 may remain in the flat surface even after the positive electrode foil extension 21C and the negative electrode foil extension 22C are bent, and the portion without the groove 43 may be joined (welded, etc.) to the positive electrode current collector plate 24 or the negative electrode current collector plate 25. Not only the flat surface, but the groove 43 may also be joined to a part of the positive electrode current collector plate 24 or the negative electrode current collector plate 25.

[0101] Figures 5A and 5B represent the negative electrode side of the battery corresponding to battery 1 shown in the schematic diagram of Figure 1. Figures 5A and 5B show the lines of the cross-sectional views in Figures 6A to 9D. Figures 5A and 5B show battery 1 with a negative electrode current collector plate 25 covering the groove 43.

[0102] Figures 6A to 6D show the positive and negative sides of the battery 1 along the grooves 43 of the positive electrode foil extension 21C and the negative electrode foil extension 22C. Figures 6A to 6D show that the bottom of the grooves 43 can be curved, and the groove 43 on the negative electrode side can be made deeper than the groove 43 on the positive electrode side. As shown in Figures 6A and 6C, the groove 43 on the positive electrode side of the battery 1 can be about 0.4 mm within the manufacturing tolerance and / or measurement tolerance, but other values ​​are also possible. Also, as shown in Figures 6B and 6D, the groove 43 on the negative electrode side of the battery 1 can be about 0.8 mm within the manufacturing tolerance and / or measurement tolerance, but other values ​​are also possible. The bend shape of the positive electrode foil extension 21C and the negative electrode foil extension 22C can be asymmetrical with respect to the central axis passing through the through hole 26.

[0103] Figures 7A to 7J show magnified portions of the positive and negative electrode sides of the battery 1 along the grooves 43 of the positive electrode foil extension 21C and the negative electrode foil extension 22C. As shown in Figures 7A to 7J, the positive electrode foil extension 21C and the negative electrode foil extension 22C include bent portions as described above. The process of forming bent portions in the positive electrode foil extension 21C and the negative electrode foil extension 22C may result in bent portions being generated in a part of the separator 23 near the positive electrode foil extension 21C and the negative electrode foil extension 22C, as well as in a part of the positive electrode active material layer 21B and the negative electrode active material layer 22B near the positive electrode foil extension 21C and the negative electrode foil extension 22C. Gaps or voids may be generated between radially adjacent portions of the positive electrode foil 21A and between radially adjacent portions of the negative electrode foil 22A. A portion of the positive electrode foil 21A and / or a portion of the negative electrode foil 22A may be folded over the innermost portion of the separator 23 so that the portion of the positive electrode foil 21A and / or a portion of the negative electrode foil 22A just reaches the through hole 26. In some applications, a portion of the positive electrode foil 21A and / or a portion of the negative electrode foil 22A may enter the through hole 26, but in other applications, a portion of the positive electrode foil 21A and a portion of the negative electrode foil 22A will not enter the through hole 26. For example, if the fixing rod is inserted into the through hole 26 with the positive electrode foil extension 21C and the negative electrode foil extension 22C folded, the fixing rod can prevent the positive electrode foil 21A and / or the negative electrode foil 22A from entering the through hole 26.

[0104] Figures 8A to 8J show cross-sections of the positive and negative sides of battery 1, including the positive electrode foil extension 21C and the negative electrode foil extension 22C, but not along the grooves 43 of the positive electrode foil extension 21C and the negative electrode foil extension 22C. Figures 8A to 8D and 8I show that radially adjacent portions of the positive electrode foil extension 21C can become closer to each other as they move away from the negative electrode active material layer 22B (i.e., the distance between radially adjacent portions of the positive electrode foil extension 21C decreases as the distance to the negative electrode active material layer 22B increases), and Figures 8E to 8H and 8J show that radially adjacent portions of the negative electrode foil extension 22C can become closer to each other as they move away from the positive electrode active material layer 21B (i.e., the distance between radially adjacent portions of the negative electrode foil extension 22C decreases as the distance from the positive electrode active material layer 21B increases). In other words, Figures 8A to 8D and 8I show that radially adjacent portions of the positive electrode foil extension 21C can become closer to each other as they move away from the laminate of the positive electrode 21, separator 23, and negative electrode 22 (i.e., the distance between radially adjacent portions of the positive electrode foil extension 21C decreases as the distance to the laminate of the positive electrode 21, separator 23, and negative electrode 22 increases), and Figures 8E to 8H and 8J show that radially adjacent portions of the negative electrode foil extension 22C can become closer to each other as they move away from the laminate of the positive electrode 21, separator 23, and negative electrode 22 (i.e., the distance between radially adjacent portions of the negative electrode foil extension 22C decreases as the distance from the positive electrode active material layer 21B increases). Furthermore, as shown in Figures 8A to 8D and 8I, adjacent radial portions of the positive electrode foil extension 21C can become closer to each other as they approach the through hole 26 (i.e., the distance between adjacent radial portions of the positive electrode foil extension 21C decreases as the distance to the through hole 26 decreases), and as shown in Figures 8E to 8H and 8J, adjacent radial portions of the negative electrode foil extension 22C can become closer to each other as they approach the through hole 26 (i.e., the distance between adjacent radial portions of the negative electrode foil extension 22C decreases as the distance to the through hole 26 decreases).If the degree of fitting includes the number of overlaps of radially adjacent portions, the overlap length of radially adjacent portions, and the number of times radially adjacent portions are sandwiched together, then, as shown in Figures 8A to 8D and 8I, the degree of fitting between radially adjacent portions of the positive foil extension 21C may increase as it approaches the through hole 26, and as shown in Figures 8E to 8H and 8J, the degree of fitting between radially adjacent portions of the negative foil extension 22C may increase as it approaches the through hole 26.

[0105] Figures 9A to 9D show cross-sections of the positive and negative sides of the battery 1, crossing the weld line and multiple grooves 43, after the positive electrode foil extension 21C or negative electrode foil extension 22C has been welded to the current collector plate 24 or 25. As shown in Figures 9B and 9D, the cross-section of the grooves 43 can have a rectangular shape even after welding. If a softer metal (i.e., a metal with a lower Young's modulus) is used for the positive electrode foil 21A or negative electrode foil 21B, the grooves 43 may lose their shape during further processing of the battery 1. In Figures 9A and 9C, because a softer aluminum is used as the positive electrode foil 21A on the positive side, the grooves 43 in the positive electrode foil 21A are crushed and lose their shape, resulting in an unclear cross-sectional shape after welding. If a harder metal (i.e., a metal with a higher Young's modulus) is used for the positive electrode foil 21A or negative electrode foil 21B, the grooves 43 can retain their shape even during further processing of the battery 1. In Figures 9B and 9D, a harder copper is used as the negative electrode foil 22A on the negative electrode side. As a result, the groove 43 in the negative electrode foil 21A retains its shape, and the cross-sectional shape remains clear even after welding.

[0106] Figures 10A and 10B show the positive electrode end 41 of battery 1 without the electrode current collector plate 24. Figures 11A and 11B show the negative electrode end 42 of battery 1 without the electrode current collector plate 25. Figures 10A and 10B show the end 41 of battery 1, after the groove 43 has been formed and the positive electrode foil extension 21C has been bent. Figures 11A and 11B show the end 42 of battery 1, after the groove 43 has been formed and the negative electrode foil extension 22C has been bent. As shown in Figures 10A to 11B, the ends 41 and 42 have substantially smooth surfaces within the manufacturing tolerances and have a glossy appearance.

[0107] Figures 12A and 12E show the positive electrode current collector plate 24 with the weld line. Figures 12B and 12F show the negative electrode current collector plate 25 with the weld line. The grooves 43 below the positive electrode current collector plate 24 and the negative electrode current collector plate 25 are shown by dashed lines. The weld line may extend radially from the central axis of the through hole 26. Each weld line may contain two or more sub-lines. Figures 12C, 12D, 12G, and 12H show six sub-lines extending parallel or substantially parallel within the manufacturing tolerance and / or measurement tolerance, but any number of sub-lines may be used. This allows for the inclusion of multiple weld lines between adjacent grooves 43.

[0108] In conventional lithium-ion batteries, for example, current extraction leads are welded to the positive electrode 21 and the negative electrode 22. However, this results in high internal resistance and causes the lithium-ion battery to overheat during discharge, making it unsuitable for high-rate discharge. Therefore, in battery 1, a positive electrode current collector plate 24 and a negative electrode current collector plate 25 are placed at ends 41 and 42, and welded at multiple points to the positive electrode foil extension 21C and negative electrode foil extension 22C located at ends 41 and 42, thereby reducing the battery's internal resistance. Bending ends 41 and 42 to create substantially flat surfaces within manufacturing tolerances can also contribute to lowering resistance.

[0109] Figures 3A and 3B show examples of current collector plates 24 and 25. Figure 3A represents the positive electrode current collector plate 24, and Figure 3B represents the negative electrode current collector plate 25. The material of the positive electrode current collector plate 24 may be a metal plate made of aluminum, aluminum alloy, or a composite thereof, for example, and the material of the negative electrode current collector plate 25 may be a metal plate made of nickel, nickel alloy, copper, copper alloy, or a composite thereof. As shown in Figures 3A, 15A, and 15C, the positive electrode current collector plate 24 includes a flat fan-shaped portion 31 and a rectangular strip-shaped portion 32. The flat fan-shaped portion 31 and the rectangular strip-shaped portion 32 may be connected to form two corners 48. As shown in Figures 3A, 15A, and 15C, the two corners 48 may each be curved. A hole 35 is located near the center of the fan-shaped portion 31, and the position of the hole 35 corresponds to the position of the through hole 26, so the hole 35 is aligned with the through hole 26. The fan-shaped portion 31 includes a curved portion and two straight portions. As shown in Figures 3A, 15A, and 15C, the lines 49 of the two straight portions may be on the same straight line or substantially on the same straight line within the manufacturing tolerance and / or measurement tolerance. The shaded portion in Figure 3A is the insulating portion 32A. The insulating portion 32A is the portion of the strip-shaped portion 32 to which insulating tape is attached or insulating material is applied. The lower part of the shaded portion is the connection portion 32B to the sealing plate which also serves as an external terminal. In the case of a battery structure that does not have a metal center pin (not shown) in the through hole 26, the possibility of the strip-shaped portion 32 coming into contact with the negative electrode potential portion is low. Therefore, the insulating portion 32A may not be necessary. In that case, the charge and discharge capacity can be increased by widening the width between the positive electrode 21 and the negative electrode 22 by an amount equivalent to the thickness of the insulating part 32A.

[0110] The shape of the negative electrode current collector plate 25 is almost the same as that of the positive electrode current collector plate 24. However, the strip portion 34 of the negative electrode current collector plate 25 is different from the strip portion 32 of the positive electrode current collector plate 24. The strip portion 34 of the negative electrode current collector plate 25 shown in Figure 3B is shorter than the strip portion 32 of the positive electrode current collector plate 24 and does not have a portion corresponding to the insulating portion 32A. The strip portion 34 is provided with a round projection 37 that can be used to weld the strip portion 35 to the outer casing 11, as shown in Figures 3B, 15B, and 15D. A flat fan-shaped portion 33 and a rectangular strip portion 34 may be connected to form two corners 48. As shown in Figures 3B, 15B, and 15D, the two corners 48 may each be curved. The fan-shaped portion 33 includes a curved portion and two straight portions. As shown in Figures 3B, 15B, and 15D, the lines 49 of the two straight sections may be collinear or substantially collinear within the manufacturing tolerance and / or measurement tolerance. During resistance welding, the current concentrates on the protrusions, causing them to melt and the strip portion 34 to be welded to the bottom of the outer casing 11. Similar to the positive electrode current collector plate 24, the negative electrode current collector plate 25 has a hole 36 near the center of the fan-shaped portion 33, and the position of the hole 36 corresponds to the position of the through hole 26, so the hole 36 is aligned with the through hole 26. The fan-shaped portion 31 of the positive electrode current collector plate 24 and the fan-shaped portion 33 of the negative electrode current collector plate 25 have a fan shape so that they cover only a portion of the ends 41, 42. The reason for not covering the holes 36 is to allow the electrolyte to penetrate smoothly into the electrode winding 20 when assembling the battery 1, or to facilitate the release of gas generated when the battery becomes abnormally hot or overcharged to the outside of the battery 1.

[0111] The positive electrode active material layer 21B contains one or more positive electrode materials capable of intercalating and deintercalating lithium as the positive electrode active material. However, the positive electrode active material layer 21B may further contain one or more other materials such as a positive electrode binder and a positive electrode conductive agent. The positive electrode material may be a lithium-containing compound, and more specifically, a lithium-containing composite oxide or a lithium-containing phosphoric acid compound.

[0112] Lithium-containing composite oxides are oxides that contain lithium and one or more other elements, i.e., elements other than lithium, as constituent elements. These oxides may have one of the following crystal structures: layered rock salt type and spinel type. Lithium-containing phosphate compounds are phosphate compounds that contain lithium and one or more other elements as constituent elements, and these compounds may have a crystal structure such as olivine type.

[0113] The positive electrode binder contains one or more of the following: synthetic rubber and polymer compounds. The synthetic rubber may be, for example, styrene-butadiene rubber, fluororubber, and ethylene-propylenediene. The polymer compound may be, for example, polyvinylidene fluoride and polyimide. The positive electrode conductive agent may contain one or more of the following: carbon materials. These carbon materials may be, for example, graphite, carbon black, acetylene black, and Ketjenblack. However, the positive electrode conductive agent may be any conductive material, such as a metallic material or a conductive polymer.

[0114] The surface of the negative electrode foil 22A may be roughened. This is because the adhesion of the negative electrode active material layer 22B to the negative electrode foil 22A is improved by the so-called anchoring effect. In this case, it is sufficient for the surface of the negative electrode foil 22A to be roughened in at least the region facing the negative electrode active material layer 22B. One method of roughening is to form fine particles using electrolytic treatment. In electrolytic treatment, fine particles are formed on the surface of the negative electrode foil 22A by electrolysis in the electrolytic cell, thus creating irregularities on the surface of the negative electrode foil 22A. Copper foil produced by electrolytic treatment is generally called electrolytic copper foil.

[0115] The negative electrode active material layer 22B may contain one or more negative electrode materials capable of intercalating and deintercalating lithium as the negative electrode active material. However, the negative electrode active material layer 22B may further contain one or more other materials such as a negative electrode binder and a negative electrode conductive agent.

[0116] The negative electrode material may be, for example, a carbon material. This is because the change in crystal structure during lithium intercalation and deintercalation is very small, allowing for a stable and high energy density. Furthermore, since carbon materials also function as negative electrode conductors, the conductivity of the negative electrode active material layer 22B is improved.

[0117] The carbon material may be, for example, easily graphitizable carbon, non-graphitizable carbon, and graphite. However, the interplanar spacing of the (002) planes in non-graphitizable carbon may be about 0.37 nm or more within the manufacturing tolerance and / or measurement tolerance. The interplanar spacing of the (002) planes in graphite may be about 0.34 nm or less within the manufacturing tolerance and / or measurement tolerance. More specifically, the carbon material may be, for example, pyrolysis carbons, cokes, glassy carbon fibers, calcined organic polymer compounds, activated carbon, and carbon blacks. These cokes include pitch coke, needle coke, and petroleum coke. Calcined organic polymer compounds are obtained by calcining (carbonizing) polymer compounds such as phenolic resins and furan resins at an appropriate temperature. In addition, the carbon material may be low-crystalline carbon heat-treated at a temperature of about 1000°C or less, or amorphous carbon. The carbon material may be fibrous, spherical, granular, or flaky in shape.

[0118] In battery 1, when the open-circuit voltage at full charge, i.e., the battery voltage, is approximately 4.25V or higher, the amount of lithium released per unit mass increases compared to when the open-circuit voltage at full charge is approximately 4.20V, even when using the same positive electrode active material. Therefore, the amounts of positive electrode active material and negative electrode active material are adjusted accordingly. This results in a high energy density.

[0119] The separator 23 is interposed between the positive electrode 21 and the negative electrode 22, allowing lithium ions to pass through while preventing a short circuit of current caused by contact between the positive electrode 21 and the negative electrode 22. The separator 23 is made of one or more of the following porous films: synthetic resin and ceramic, or a laminated film of two or more porous films. The synthetic resin may be, for example, polytetrafluoroethylene, polypropylene, and polyethylene.

[0120] In particular, the separator 23 may include, for example, a porous film as the base layer described above and a polymer compound layer provided on one or both sides of the base layer. This is because the adhesion of the separator 23 to the positive electrode 21 and the negative electrode 22 is improved, thereby suppressing distortion of the electrode winding 20. As a result, the decomposition reaction of the electrolyte is suppressed, and leakage of the electrolyte impregnated into the base layer is also suppressed, so that the resistance does not increase easily even after repeated charging and discharging, and swelling of the secondary battery is suppressed.

[0121] The polymer compound layer contains, for example, a polymer compound such as polyvinylidene fluoride. This is because the polymer compound has excellent physical strength and is electrochemically stable. However, the polymer compound may be other than polyvinylidene fluoride. When forming this polymer compound layer, for example, a solution in which the polymer compound is dissolved in an organic solvent is applied to the substrate layer, and then the substrate layer is dried. Alternatively, the substrate layer may be immersed in the solution, and then the substrate layer is dried. This polymer compound layer may contain, for example, one or more types of insulating particles such as inorganic particles. Examples of inorganic particles include aluminum oxide or aluminum nitride.

[0122] The electrolyte contains a solvent and an electrolyte salt. However, the electrolyte may also contain one or more other materials, such as additives.

[0123] The solvent contains one or more non-aqueous solvents, such as organic solvents. An electrolyte containing a non-aqueous solvent is a so-called non-aqueous electrolyte.

[0124] Non-aqueous solvents include, for example, cyclic carbonate esters, linear carbonate esters, lactones, linear carboxylic acid esters, or nitriles (mononitriles). The electrolyte salt contains one or more types of salts, such as lithium salts. However, the electrolyte salt may also contain salts other than lithium salts. These salts other than lithium are, for example, salts of light metals other than lithium.

[0125] Lithium salts may include, for example, lithium hexafluoride phosphate (LiPF6), lithium tetraborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoride arsenate (LiAsF6), lithium tetraphenylborate (LiB(C6H5)4), lithium methanesulfonate (LiCH3SO3), lithium trifluoromethanesulfonate (LiCF3SO3), lithium tetrachloroaluminate (LiAlCl4), dilithium hexafluorosilicate (Li2SF6), lithium chloride (LiCl), and lithium bromide (LiBr).

[0126] One or more of the following may be used: lithium hexafluoride phosphate, lithium tetrafluoroborate, lithium perchlorate, and lithium hexafluoride arsenate.

[0127] The electrolyte salt content is not particularly limited, but may range from about 0.3 mol / kg to about 3 mol / kg within the manufacturing tolerance and / or measurement tolerance relative to the solvent.

[0128] The manufacturing method of battery 1 will be described with reference to Figures 4A to 4F. First, the positive electrode active material 21B may be applied to the surface of a strip-shaped positive electrode foil 21A to form a coated portion and an uncoated portion of the positive electrode 21 (for example, a positive electrode foil extension portion 21C), and the negative electrode active material 22B may be applied to the surface of a strip-shaped negative electrode foil 22A to form a coated portion and an uncoated portion of the negative electrode 22 (for example, a negative electrode foil extension portion 22C). A positive electrode foil extension portion 21C and a negative electrode foil extension portion 22C may be made at one end of the positive electrode 21 in the short direction and one end of the negative electrode 22 in the short direction, respectively, where the positive electrode active material 21B and negative electrode active material 21B are not applied. A notch may be formed in a part of the positive electrode foil extension portion 21C and the negative electrode foil extension portion 22C that corresponds to the starting point when winding. The positive electrode 21 and the negative electrode 22 may undergo processes such as drying. The positive electrode 21 and the negative electrode 22 may be stacked via a separator 23 such that the positive electrode foil extension portion 21C of the positive electrode 21 and the negative electrode foil extension portion 22C of the negative electrode 22 are in opposite directions, and they may be wound in a spiral shape so that a through hole 26 is created and the central axis passes through the through hole 26, and the notch is positioned near the central axis. This makes it possible to produce an electrode winding body 20 as shown in Figure 4A.

[0129] Next, as shown in Figure 4B, a groove 43 may be formed by locally bending the ends 41 and 42 by pressing the edge of a thin flat plate (e.g., 0.5 mm thick) perpendicular or substantially perpendicular to the ends 41 and 42 within the manufacturing tolerance and / or measurement tolerance. The groove 43 may be formed using a blunt grooving tool so as not to damage the positive electrode foil 21A and the negative electrode foil 22A. A groove 43 can be formed radially from the through hole 26, extending toward the central axis. The number and arrangement of grooves 43 shown in Figure 4B are merely examples, and any number and arrangement of grooves 43 can be used. Then, as shown in Figure 4C, the positive electrode foil extension 21C of the positive electrode 21 and the negative electrode foil extension 22C of the negative electrode 22 may be bent by applying the same pressure simultaneously from both electrode sides perpendicular or substantially perpendicular to the ends 41 and 42, so that the ends 41 and 42 become flat surfaces. A load can be applied, such as from a flat plate surface, so that a bent portion of the positive electrode foil extension 21C at end 41 bends and overlaps toward the through hole 26, and a bent portion of the negative electrode foil extension 22C at end 42 bends and overlaps toward the through hole 26. Subsequently, the fan-shaped portion 31 of the positive electrode current collector plate 24 is joined to end 41, for example by laser welding, and the fan-shaped portion 33 of the negative electrode current collector plate 25 is joined to end 42, for example by laser welding.

[0130] Subsequently, as shown in Figure 4D, the strip-shaped portions 32 and 34 of the current collector plates 24 and 25 may be bent, and insulating plates 12 and 13 (or insulating tape) may be attached to the positive electrode current collector plate 24 and the negative electrode current collector plate 25. As shown in Figures 13A, 13B, 13C, 13F, and 13G, an insulator 53 may be applied to the positive electrode end of the electrode winding body 20, and as shown in Figures 13A, 13D, 13E, 13H, and 13I, an insulator 54 may be applied to the negative electrode end of the electrode winding body 20. The insulator 53 may cover a portion of the side surface and a portion of the end 41 of the electrode winding 20 so that the rectangular strip portion 32 of the positive electrode current collector plate 24 extends away from the end 41, and the insulator 54 may cover a portion of the side surface and a portion of the end 42 of the electrode winding 20 so that the strip portion 34 of the negative electrode current collector plate 25 extends away from the end 42. As shown in Figures 14A, 14B, 14C, 14F and 14G, the insulating plate 12 may include an outlet for the rectangular strip portion 32 of the positive electrode current collector plate 24 to pass through, a relatively large hole 45 corresponding to and aligned with the through hole 26 of the electrode winding 20, and a plurality of relatively small holes 46 arranged around the relatively large hole 45, through which the electrolyte can pass. As shown in Figures 14A, 14D, 14E, 14H, and 14I, the insulating plate 13 may include an outlet for the strip portion 34 of the negative electrode current collector plate 25 to pass through, and a hole that corresponds to and is aligned with the through hole 26 of the electrode winding body 20.

[0131] After attaching insulating plates 12 and 13 to the positive electrode current collector plate 24 and the negative electrode current collector plate 25, the electrode winding body 20 assembled as described above may be inserted into the outer casing 11 shown in Figure 4E, and the bottom of the outer casing 11 may be welded. After injecting the electrolyte into the outer casing 11, it may be sealed with a gasket 15 and a battery cover 14 as shown in Figure 4F.

[0132] It should be understood that the above description is merely illustrative of the present invention. Those skilled in the art can make various modifications and changes without departing from the scope of the present invention. Accordingly, the present invention is intended to encompass such modifications, changes, and differences, insofar as they fall within the scope of the appended claims.

Claims

1. Positive electrode foil and A positive electrode active material provided on a portion of the positive electrode foil, A positive electrode foil extension portion that extends from the positive electrode foil and on which the positive electrode active material is not provided, and A positive electrode having, Negative electrode foil and A negative electrode active material provided on a portion of the negative electrode foil, A negative electrode foil extension portion that extends from the negative electrode foil and on which the negative electrode active material is not provided, A negative electrode having, A separator provided between the positive electrode and the negative electrode An electrode winding body comprising, The positive electrode, the negative electrode, and the separator are wound in a spiral shape with through holes, and the central axis passes through the through holes. The positive electrode foil extension extends from the first end of the electrode winding body, The negative electrode foil extension extends from the second end of the electrode winding body opposite to the first end, A portion of the positive electrode foil extension includes a first bent portion that is bent toward the central axis such that a first surface is defined by the overlapping of a portion of the positive electrode foil extension. The positive electrode foil extension portion has a first groove on the first surface, A portion of the negative electrode foil extension includes a second bent portion that is bent toward the central axis such that a second surface is defined by the overlapping of a portion of the negative electrode foil extension. The negative electrode foil extension has a second groove on the second surface. Electrode winding body.

2. The bottom surface of the first groove is curved, The bottom surface of the second groove is curved. The electrode winding body according to claim 1.

3. The first curvature of the first groove is smaller than the second curvature of the second groove. The electrode winding body according to claim 2.

4. The second groove is deeper than the first groove. The electrode winding body according to any one of claims 1 to 3.

5. The first groove and the second groove each have a rectangular cross-section. The electrode winding body according to any one of claims 1 to 4.

6. A portion of the separator includes a third bent portion. The electrode winding body according to any one of claims 1 to 5.

7. A portion of the positive electrode active material includes a fourth bent portion, A portion of the negative electrode active material includes a fifth bent portion. The electrode winding body according to any one of claims 1 to 6.

8. A portion of the positive electrode foil and / or a portion of the negative electrode foil is folded over the innermost portion of the separator that is closest to the through hole. The electrode winding body according to any one of claims 1 to 7.

9. A portion of the positive electrode foil extension includes a plurality of first bent portions, A portion of the negative electrode foil extension includes a plurality of second bent portions, The number of the plurality of first bends in the positive electrode foil extension is greater than the number of the plurality of second bends in the negative electrode foil extension. The electrode winding body according to any one of claims 1 to 8.

10. The first bend shape of the first bent portion of the positive electrode foil extension is asymmetrical with respect to the central axis. The second bend shape of the second bend in the negative electrode foil extension is asymmetrical with respect to the central axis. The electrode winding body according to any one of claims 1 to 9.

11. The positive electrode foil extension is further provided with a gap between adjacent first bends in the radial direction or between adjacent second bends in the radial direction of the negative electrode foil extension. The electrode winding body according to any one of claims 1 to 10.

12. The first surface is a substantially smooth surface and has a glossy appearance. The second surface is substantially smooth and has a glossy appearance. The electrode winding body according to any one of claims 1 to 11.

13. The first distance between adjacent radially adjacent portions of the positive electrode foil extension decreases as the second distance to the negative electrode active material increases. The third distance between adjacent radially adjacent portions of the negative electrode foil extension decreases as the fourth distance from the positive electrode active material increases. The electrode winding body according to any one of claims 1 to 12.

14. The first distance between adjacent radially adjacent portions of the positive electrode foil extension decreases as the second distance to the through hole decreases. The third distance between adjacent radially adjacent portions of the negative electrode foil extension decreases as the fourth distance to the through hole decreases. The electrode winding body according to any one of claims 1 to 12.

15. The degree of fitting between radially adjacent portions of the positive electrode foil extension increases as the first distance to the through hole decreases. The degree of fitting between radially adjacent portions of the negative electrode foil extension increases as the second distance to the through hole decreases. The electrode winding body according to any one of claims 1 to 14.

16. The outer can and The electrode winding body according to any one of claims 1 to 15 is provided inside the outer can. A battery equipped with these features.

17. A positive electrode current collector plate is bonded to the first surface and includes a flat first fan-shaped portion and a rectangular first strip-shaped portion, A negative electrode current collector plate is joined to the second surface and includes a flat second fan-shaped portion and a rectangular second strip-shaped portion. The battery according to claim 16, further comprising:

18. After the positive electrode current collector plate is joined to the first surface and the negative electrode current collector plate is joined to the second surface, the first groove does not maintain its cross-sectional shape, while the second groove maintains its cross-sectional shape. The battery according to claim 17.

19. The first fan-shaped portion of the positive electrode current collector plate includes a first curved portion and two first straight portions, and the two first lines of the two first straight portions are on the same straight line. The second fan-shaped portion of the negative electrode current collector plate includes a second curved portion and two second straight portions, wherein the two second lines of the two second straight portions are on the same straight line. The battery according to claim 17 or claim 18.

20. The flat first fan-shaped portion and the rectangular first strip-shaped portion of the positive electrode current collector plate are connected by two curved first corners. The flat second fan-shaped portion and the rectangular second strip-shaped portion of the negative electrode current collector plate are connected by two curved second corners. The battery according to any one of claims 17 to 19.

21. A positive electrode insulator is bonded to the positive electrode current collector plate and has a relatively large hole aligned with the through hole, and a plurality of relatively small holes arranged around the relatively large hole, A negative electrode insulator is bonded to the negative electrode current collector plate and has a hole aligned with the through hole. The battery according to any one of claims 17 to 20, further comprising the above.

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