SECOND BATTERY AND BATTERY PACK

Abstract

In a secondary battery (1), a first end face (41) of an electrode winding body (20) and a first electrode current collector plate (24) are connected to each other by one or more first connecting parts (61). In a top view, each of the one or more first connecting parts has a meandering shape. The meandering shape has several first linear sections (61A) and several first reversing sections (61B). In each of the one or more first connecting parts, a length in a winding direction of the electrode winding body from an a-th to an (a + 1)-th of the first reversing sections, counted from a winding center of the electrode winding body, is longer than a length in the winding direction from a first to a second of the first reversing sections of a corresponding first connecting part, counted from the winding center.

Description

BACKGROUND

[0001] The disclosure relates to a secondary battery and a battery pack that includes the secondary battery.

[0002] Various types of electronic devices, including mobile phones, are widely used. This widespread use has spurred the development of a secondary battery as an energy source, which is smaller in size and weight and offers a higher energy density. The secondary battery comprises a battery device contained within an outer packaging element. Various configurations of the secondary battery have been considered.

[0003] For example, International Publication No. WO 2021 / 020237 proposes a secondary battery that uses a so-called tabless structure. Such a secondary battery achieves a lower internal resistance and allows charging and discharging with a relatively high current. SUMMARY

[0004] A secondary battery according to one embodiment of the disclosure comprises an electrode winding body, a first electrode current collector plate, and a second electrode current collector plate. The electrode winding body includes a stacked body and has a through-hole. The stacked body includes a first electrode, a second electrode, and a separator and is wound along a longitudinal direction of the stacked body. The through-hole extends through the electrode winding body in a lateral direction that is orthogonal to the longitudinal direction. The first electrode current collector plate and the second electrode current collector plate are opposite each other, with the electrode winding body being arranged laterally between the first electrode current collector plate and the second electrode current collector plate. The electrode winding body has a first end face and a second end face.The first end face faces the first electrode current collector plate in the width direction. The second end face faces the second electrode current collector plate in the width direction. The first electrode current collector plate and the first end face are connected to each other by means of one or more first connecting elements. In a top view, each of these first connecting elements has a meandering shape in a plane orthogonal to the through-hole. The meandering shape comprises several first linear sections and several first reversing sections. The first linear sections are adjacent to each other in a radial direction along the electrode winding body. The first reversing sections couple the first linear sections together.In each of the one or more first connecting parts, a length in a winding direction of the electrode winding body from an a-th of the first reversing sections, counted from a winding center of the electrode winding body, to an (a + 1)-th of the first reversing sections, counted from the winding center, is longer than a length in the winding direction from a first of the first reversing sections, of a corresponding first connecting part, counted from the winding center, to a second of the first reversing sections, of the corresponding first connecting part, counted from the winding center, where a number of first reversing sections is represented by “n”, “n” is a natural number and “a” is a natural number greater than or equal to two and less than “n”.

[0005] A battery pack according to one embodiment of the disclosure comprises a secondary battery, a control device, and an outer packaging body. The processor is configured to control the secondary battery. The outer packaging body contains the secondary battery. The secondary battery comprises an electrode winding body, a first electrode current collector plate, and a second electrode current collector plate. The electrode winding body comprises a stack body and has a through-hole. The stack body comprises a first electrode, a second electrode, and a separator and is wound along a longitudinal direction of the stack body. The through-hole extends through the electrode winding body in a lateral direction that is orthogonal to the longitudinal direction.The first electrode current collector plate and the second electrode current collector plate are positioned opposite each other, with the electrode winding body arranged in the width direction between the first and second electrode current collector plates. The electrode winding body has a first end face and a second end face. The first end face faces the first electrode current collector plate in the width direction. The second end face faces the second electrode current collector plate in the width direction. The first electrode current collector plate and the first end face are connected to each other by means of one or more first connecting parts. In a top view, each of the one or more first connecting parts has a meandering shape in a plane orthogonal to the through-hole. The meandering shape has several first linear sections and several first reversal sections.The first linear sections are adjacent to each other in a radial direction of the electrode core. The first reversal sections couple the first linear sections together. In each of the one or more first connecting sections, a length in a winding direction of the electrode core from an a-th of the first reversal sections, counted from a winding center of the electrode core, to an (a + 1)-th of the first reversal sections, counted from the winding center, is longer than a length in the winding direction from a first of the first reversal sections, a corresponding first connecting section, counted from the winding center, to a second of the first reversal sections, a corresponding first connecting section, counted from the winding center, where a number of first reversal sections is represented by "n", "n" is a natural number, and "a" is a natural number greater than or equal to two and less than "n". BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The accompanying drawings serve to enhance understanding of the revelation and are an integral part of this description. The drawings illustrate exemplary embodiments and, together with the description, serve to explain the principles of revelation. Fig. Figure 1 is a sectional view showing a configuration example of a vertical section structure along a height direction of a secondary battery according to an embodiment of the disclosure. Fig. Figure 2 is a schematic representation of a configuration example of a stacked body with a positive electrode, a negative electrode, and a separator, as shown in Fig. 1 shown. Fig. 3 is a sectional view that shows a configuration example of a horizontal section structure of a Fig. Figure 1 shows the electrode winding body. Fig. 4A is a flattened view of the in Fig. 1 positive electrode shown. Fig. 4B is a sectional view of the Fig. 1 positive electrode shown. Fig. 5A is a flattened view of the in Fig. 1 negative electrode shown. Fig. 5B is a sectional view of the Fig. 1 negative electrode shown. Fig. 6A is a top view showing an upper end face of the in Fig. Figure 1 shows the electrode winding body. Fig. 6B is a top view showing a lower end face of the in Fig. Figure 1 shows the electrode winding body. Fig. 7A is a top view of a Fig. 1. Positive electrode current collector plate shown. Fig. 7B is a top view of a Fig. 1. Negative electrode current collector plate shown. Fig. 8A is a top view showing a configuration example of a first connecting part between the upper end face of the electrode winding body and the in Fig. The positive electrode current collector plate shown in Figure 1 is shown. Fig. 8B is a top view showing a configuration example of a second connecting part between the lower end face of the electrode winding body and the in Fig. Figure 1 shows the negative electrode current collector plate. Fig. 9A is an enlarged schematic top view of the in Fig. 8A shows the first connecting part. Fig. 9B is a sectional view showing a section of the Fig. 8A shows the first connecting part and its surroundings. Fig. 10A is an enlarged schematic top view of the in Fig. 8B shows the second connecting part. Fig. 10B is a sectional view showing a section of the Fig. 8B shows the second connecting part and its surroundings. Fig. 11A to Fig. 11F are each perspective drawings that depict a manufacturing process of the in Fig. Describe the secondary battery shown in Figure 1. Fig. Figure 12 is a block diagram showing a circuit configuration of a battery pack to which the secondary battery is applied according to an exemplary embodiment of the disclosure. Fig. Figure 13A is a top view showing a configuration example of a first connecting part between an upper end face of an electrode winding body and a positive electrode current collector plate in a secondary battery according to a first modification example of an exemplary embodiment of the present disclosure. Fig. 13B is an enlarged schematic top view of the first connecting part of the in Fig. 13A shows the first modification example. Fig. Figure 14A is a top view showing a configuration example of a first connecting part between an upper end face of an electrode winding body and a positive electrode current collector plate in a secondary battery according to a second modification example of an exemplary embodiment of the present disclosure. Fig. 14B is an enlarged schematic top view of the first connecting part of the in Fig. 14A, the second modification example shown. Fig. Figure 15A is a top view showing a configuration example of a first connecting part between an upper end face of an electrode winding body and a positive electrode current collector plate in a secondary battery according to a first example of a third modification example of an exemplary embodiment of the present disclosure. Fig. Figure 15B is a top view showing a configuration example of a first connecting part between an upper end face of an electrode winding body and a positive electrode current collector plate in a secondary battery according to a second example of the third modification example of an exemplary embodiment of the present disclosure. Fig. Figure 16 is a top view showing a configuration example of a first connecting part between an upper end face of an electrode winding body and a positive electrode current collector plate in a secondary battery according to a fourth modification example of an exemplary embodiment of the present disclosure. Fig. Figure 17 is a top view showing a configuration example of a first connecting part between an upper end face of an electrode winding body and a positive electrode current collector plate in a secondary battery according to a fifth modification example of an exemplary embodiment of the present disclosure. Fig. Figure 18 is a top view showing a configuration example of a first connecting part between an upper end face of an electrode winding body and a positive electrode current collector plate in a secondary battery according to a sixth modification example of an exemplary embodiment of the present disclosure. Fig. Figure 19 is a top view showing a configuration example of a first connecting part between an upper end face of an electrode winding body and a positive electrode current collector plate in a secondary battery according to a seventh modification example of an exemplary embodiment of the present disclosure. Fig. Figure 20 is a top view showing a configuration example of a first connecting part between an upper end face of an electrode winding body and a positive electrode current collector plate in a secondary battery according to an eighth modification example of an exemplary embodiment of the present disclosure. Fig. Figure 21 is a top view showing a configuration example of a first connecting part between an upper end face of an electrode winding body and a positive electrode current collector plate in a secondary battery according to a ninth modification example of an exemplary embodiment of the present disclosure. Fig. Figure 22 is a top view showing a configuration example of a first connecting part between an upper end face of an electrode winding body and a positive electrode current collector plate in a secondary battery according to a tenth modification example of an exemplary embodiment of the present disclosure. Fig. Figure 23 is a top view showing a first connecting part between an upper end face of an electrode winding body and a positive electrode current collector plate in a secondary battery as a first comparative example. Fig. Figure 24A is a top view showing a first connecting part between an upper end face of an electrode winding body and a positive electrode current collector plate in a secondary battery as a second comparative example. Fig. 24B is an enlarged schematic top view of the in Fig. 24A first connecting part shown. DETAILED DESCRIPTION

[0007] Various approaches have been considered to improve the performance of a secondary battery. However, there is still room for improvement regarding the performance of the secondary battery.

[0008] It is desirable to provide a secondary battery with superior performance, and to provide a battery pack that incorporates such a secondary battery.

[0009] Some embodiments of the disclosure are described in detail below with reference to the accompanying drawings. It should be noted that the following description refers to illustrative examples of the disclosure and is not to be construed as a limitation of the disclosure. Factors, including but not limited to numerical values, shapes, materials, components, positions of the components, and the manner in which the components are coupled, are for illustrative purposes only and are not to be construed as a limitation of the disclosure. Furthermore, elements in the following embodiments that are not mentioned in a most general independent claim of the disclosure are optional and may be provided as required. The drawings are schematic and not to scale.In this description and the drawings, elements that have essentially the same function and configuration are designated with the same reference numerals to avoid redundant description. Furthermore, elements not directly related to an embodiment of the disclosure are not shown in the drawings. The description follows this order. 1. Secondary battery 1-1. Configuration 1-2. Operation 1-3. Manufacturing processes 1-4. Impact and exemplary effects 2. Application examples 2-1. Battery pack 2-2. Power storage system 3. Modification Examples [1. Secondary battery]

[0010] First, a secondary battery according to an exemplary embodiment of the disclosure is described.

[0011] In the present embodiment, a cylindrical lithium-ion secondary battery is described as an example, which has an external appearance of a cylindrical shape. However, a secondary battery of an embodiment of the disclosure is not limited to the cylindrical lithium-ion secondary battery and can be a lithium-ion secondary battery with an external appearance of a shape other than cylindrical, or a secondary battery in which an electrode reactant other than lithium is used.

[0012] Although the charging and discharging principle of a secondary battery is not particularly restrictive, the following description deals with a case in which battery capacity is achieved by the deposition and extraction (or removal) of the electrode reactant. The secondary battery can have a positive electrode, a negative electrode, and an electrolyte. To prevent the deposition of the electrode reactant on the surface of the negative electrode during charging, the charging capacity of the negative electrode can be greater than the discharging capacity of the positive electrode. For example, the electrochemical capacity per unit area of ​​the negative electrode can be set higher than the electrochemical capacity per unit area of ​​the positive electrode.

[0013] As described above, the electrode reactant is not particularly restricted in its type. For example, the electrode reactant can be a light metal such as an alkali metal or an alkaline earth metal. Non-restrictive examples of alkali metals include lithium, sodium, and potassium. Non-restrictive examples of alkaline earth metals include beryllium, magnesium, and calcium.

[0014] The following example describes a case where the electrode reactant is lithium. A secondary battery in which the battery capacity is achieved by the insertion and extraction (or removal) of lithium can be a so-called lithium-ion secondary battery. In a lithium-ion secondary battery, lithium can be inserted and removed in its ionic state. [1-1. Configuration][Lithium-ion secondary battery 1]

[0015] Fig. Figure 1 shows a vertical sectional configuration of a lithium-ion secondary battery 1 according to the present exemplary embodiment along a vertical direction. The lithium-ion secondary battery 1 according to the present exemplary embodiment may hereinafter be referred to simply as "secondary battery 1". The in Fig. The secondary battery 1 shown in Figure 1 can have an outer packaging container 11 and an electrode winding body 20. The outer packaging container 11 can have a substantially cylindrical shape. The electrode winding body 20 can be contained within the outer packaging container 11 and serve as the battery device. The secondary battery 1 can further have an outer packaging tube 50. The outer packaging tube 50 can cover an outer peripheral surface of the outer packaging container 11. It should be noted that the vertical direction of the secondary battery 1 here corresponds to a Z-axis direction.

[0016] For example, the secondary battery 1 may, within the outer packaging container 11, comprise a pair of insulating plates 12 and 13, the electrode winding body 20, a positive electrode current collector plate 24, and a negative electrode current collector plate 25. The electrode winding body 20 may, for example, be a structure in which a positive electrode 21 and a negative electrode 22 are stacked and wound together with a separator 23 interposed. The electrode winding body 20 may be impregnated with an electrolyte solution. The electrolyte solution may be a liquid electrolyte. In some embodiments, the secondary battery 1 may further comprise a thermosensitive resistance device, a gain element, or both within the outer packaging container 11. Non-limiting examples of the thermosensitive resistance device may include a positive temperature coefficient (PTC) device.

[0017] The positive electrode current collector plate 24 can correspond to a specific, but not limiting, example of a “first electrode current collector plate” in an embodiment of the disclosure. The negative electrode current collector plate 25 can correspond to a specific, but not limiting, example of a “second electrode current collector plate” in an embodiment of the disclosure. [Outer packaging can 11]

[0018] The outer packaging box 11 can include components such as, but not limited to, the positive electrode current collector plate 24, the negative electrode current collector plate 25, and the electrode winding body 20. The outer packaging box 11 can have a bottom section 11B and a side wall section 11W. The bottom section 11B can also serve as a negative electrode connection, which is coupled to the negative electrode 22 via the negative electrode current collector plate 25. The outer packaging box 11 can, for example, have a hollow cylindrical structure with a lower end section and an upper end section in the Z-axis direction. The lower end section can be closed, and the upper end section can be open. The upper end section of the outer packaging box 11 can thus be an open end section 11N.The lower end section of the outer packaging container 11 can be closed or sealed by the base section 11B, which has a substantially circular plate shape. The side wall section 11W can be positioned between the open end section 11N and the base section 11B and surrounds the electrode winding body 20. The side wall section 11W can extend vertically and along an outer edge of the base section 11B to surround the electrode winding body 20. The side wall section 11W can have the open end section 11N on a side opposite the base section 11B. The open end section 11N can be open to allow the electrode winding body 20 to pass through it. The outer packaging container 11 can, for example, contain a metallic material such as iron.In some embodiments, a surface of the outer packaging container 11 may be plated with a metallic material such as nickel. The insulating plate 12 and the insulating plate 13 may, for example, be arranged opposite each other such that the electrode winding body 20 is positioned between them in the Z-axis direction. It should be noted that the open end section 11N and its surroundings may be referred to as the upper part of the secondary battery 1 in the Z-axis direction, and a region in which the outer packaging container 11 is closed and its surroundings may be referred to as the lower part of the secondary battery 1 in the Z-axis direction. [Outer packaging tube 50]

[0019] The outer packaging tube 50 can surround a side surface 11WS, which is an outer surface of the side wall section 11W of the outer packaging container 11. In some embodiments, the outer packaging tube 50 can cover a bent part 11P positioned at the upper end section of the outer packaging container 11, as shown in Fig. Figure 1 shows the bent section 11P, which is described later. In some embodiments, the outer packaging tube 50 can cover part of a bottom surface 11BS, which is an outer surface of the bottom section 11B of the outer packaging can 11. The outer packaging tube 50 can, for example, have a heat-shrinkable insulating film made of a material such as a polyester resin, a polyamide resin, or a thermoplastic elastomer resin. [Washer 55]

[0020] A washer 55 can be provided in a gap between the outer packaging tube 50 and the bent part 11P of the outer packaging can 11. The washer 55 can be an insulating ring element having an opening 55K in a central region in a plane perpendicular to the vertical direction. A protruding part 14T can be arranged in the opening 55K, which is provided in a central region of a battery cover 14. The washer 55 can have a material such as black modified polyphenylene ether as a component. [Insulating panels 12 and 13]

[0021] Each of the insulating plates 12 and 13 can, for example, be a shell-shaped plate with a surface perpendicular to a central axis CL as a winding center of the electrode winding body 20, that is, a surface perpendicular to a Z-axis in Fig. 1. The insulating plates 12 and 13 can be arranged such that the electrode winding body 20 is positioned between them in the Z-axis direction. [Crimped structure 11R]

[0022] For example, a structure can be provided at the open end section 11N of the outer packaging container 11, in which the battery cover 14 and a safety valve mechanism 30 are crimped with a seal 15 located between the open end section 11N and both the battery cover 14 and the safety valve mechanism 30. This structure can be referred to as a crimped structure 11R. The outer packaging container 11 can be closed or sealed by the battery cover 14, containing the electrode winding body 20 and other components within the outer packaging container 11. The crimped structure 11R can include the bent part 11P, which serves as the crimp part. A narrow section 11S can be provided between the bent part 11P and the insulating plate 12. The narrow section 11S can be a part of the outer packaging container 11 that protrudes inwards. [Battery cover 14]

[0023] The battery cover 14 can, for example, be a closing element that closes the open end section 11N in a state where the electrode winding body 20 and other components are contained within the outer packaging container 11. The battery cover 14 can, for example, be an electrical conductor made of a material similar to that contained in the outer packaging container 11. The battery cover 14 can close the open end section 11N of the outer packaging container 11 and can be coupled to the positive electrode current collector plate 24. Therefore, the battery cover 14 can also serve as a positive electrode terminal, which is coupled to the positive electrode 21 via the positive electrode current collector plate 24. The projecting portion 14T provided in the central region of the battery cover 14 can, for example, protrude upwards, i.e., in a +Z direction.As a result, for example, a peripheral area, that is, an area different from the central area, of the battery cover 14 can be in contact with the safety valve mechanism 30. [Seal 15]

[0024] The seal 15 can, for example, be a sealing element arranged or interposed between the bent part 11P of the outer packaging container 11 and the battery cover 14. The seal 15 can seal a gap between the bent part 11P and the battery cover 14. In some embodiments, a surface of the seal 15 can be coated with a material such as asphalt. The seal 15 can, for example, comprise one or more insulating materials. The type of insulating material is not particularly restricted, and non-limiting examples include a polymeric material such as polybutylene terephthalate (PBT) or polypropylene (PP). In some embodiments, the insulating material can be polybutylene terephthalate.One reason for this is that it helps to ensure sufficient sealing of the gap between the bent part 11P and the battery cover 14, with the outer packaging box 11 and the battery cover 14 being electrically isolated from each other. [Safety valve mechanism 30]

[0025] The safety valve mechanism 30 can, for example, be adapted to release the sealed state of the outer packaging container 11, thereby releasing pressure within the outer packaging container 11, i.e., internal pressure of the outer packaging container 11, when the internal pressure of the outer packaging container 11 increases. Non-restrictive examples of a cause for an increase in the internal pressure of the outer packaging container 11 include a gas generated due to a decomposition reaction of the electrolyte solution during charging and discharging. The internal pressure of the outer packaging container 11 can also increase due to external heating. [Electrode winding body 20]

[0026] The electrode winding body 20 can be arranged between the positive electrode current collector plate 24 and the negative electrode current collector plate 25. The electrode winding body 20 has an upper end surface 41 and a lower end surface 42. The upper end surface 41 faces the positive electrode current collector plate 24 in the vertical direction. The lower end surface 42 faces the negative electrode current collector plate 25 in the vertical direction. The electrode winding body 20 can be a power generation device that initiates charging and discharging processes and can be contained within the outer packaging container 11. The electrode winding body 20 has the positive electrode 21, the negative electrode 22, and the separator 23. The electrode winding body 20 can also contain the electrolyte solution, i.e., a liquid electrolyte.

[0027] The positive electrode 21 can correspond to a specific, but not limiting, example of a "first electrode" in an embodiment of the disclosure. The negative electrode 22 can correspond to a specific, but not limiting, example of a "second electrode" in an embodiment of the disclosure. The upper end surface 41 can correspond to a specific, but not limiting, example of a "first end surface" in an embodiment of the disclosure. The lower end surface 42 can correspond to a specific, but not limiting, example of a "second end surface" in an embodiment of the disclosure.

[0028] Fig. Figure 2 is an unfolded view of the electrode winding body 20. In other words, Fig. Figure 2 schematically shows a section of a stacking body S20, corresponding to the electrode winding body 20 in an unwound state. The stacking body S20 comprises the positive electrode 21, the negative electrode 22, and the separator 23. In the stacking body S20, the positive electrode 21 and the negative electrode 22 can be stacked on top of each other with the separator 23 interposed. The separator 23 can, for example, have two bases, namely a first separator element 23A and a second separator element 23B. The electrode winding body 20 can thus have the four-layer stacking body S20. In the four-layer stacking body S20, the positive electrode 21, the first separator element 23A, the negative electrode 22, and the second separator element 23B can be stacked in this order.The positive electrode 21, the first separator element 23A, the negative electrode 22 and the second separator element 23B can each be an essentially ribbon-shaped element in which a W-direction corresponds to a transverse direction and an L-direction to a longitudinal direction.

[0029] As in Fig. As shown in Figure 3, the electrode winding body 20 can be the stacking body S20, which is wound around a through-hole 26 extending along the central axis CL in the Z-axis direction such that it forms a spiral shape in a horizontal cross-section orthogonal to the Z-axis direction. The stacking body S20 can be wound in an orientation in which the W-direction substantially coincides with the Z-axis direction. It should be noted that Fig. Figure 3 illustrates a configuration example of the electrode winding body 20 along the horizontal cross-section, which runs orthogonally to the Z-axis direction. It should be noted that in Fig. Figure 3 has been omitted for better visibility of the separator 23. The electrode winding body 20 can have an overall external appearance of an essentially circular, columnar shape. The positive electrode 21 and the negative electrode 22 can be wound in such a way that they are opposite each other with the separator 23 interposed. The electrode winding body 20 can have the through-hole 26 as an interior space in its center. The through-hole 26 can be a hole into which a winding core for assembling the electrode winding body 20 and an electrode rod for welding are each to be inserted. The through-hole 26 can extend in the Z-axis direction along the central axis CL and extends through the electrode winding body 20. The stack body S20 can thus be wound around the through-hole 26.

[0030] The positive electrode 21, the negative electrode 22, and the separator 23 can be wound such that the separator 23 is located in an outermost winding of the electrode coil body 20 and in an innermost winding of the electrode coil body 20. In the outermost winding of the electrode coil body 20, the negative electrode 22 can be arranged on the outside relative to the positive electrode 21. For example, as in Fig. As shown in Figure 3, an outermost positive electrode winding section 21out, positioned in an outermost winding of the positive electrode 21 within the electrode winding body 20, is arranged on an inner side relative to an outermost negative electrode winding section 22out, which is positioned in an outermost winding of the negative electrode 22 within the electrode winding body 20. Here, the outermost positive electrode winding section 21out can be a section corresponding to the outermost single winding of the positive electrode 21 in the electrode winding body 20. The outermost negative electrode winding section 22out can be a section corresponding to the outermost single winding of the negative electrode 22 in the electrode winding body 20. In contrast, in the innermost winding of the electrode winding body 20, the negative electrode 22 can be arranged on the inner side relative to the positive electrode 21. For example, as shown in Figure 3, the outermost positive electrode winding section 21out can be arranged on the inner side relative to the positive electrode 21. Fig. Figure 3 shows an innermost negative electrode winding section 22in, positioned in an innermost winding of the negative electrode 22 within the electrode winding body 20, relative to an innermost positive electrode winding section 21in, positioned in an innermost winding of the positive electrode 21 within the electrode winding body 20. The innermost positive electrode winding section 21in can be a section corresponding to the innermost single winding of the positive electrode 21 in the electrode winding body 20. The innermost negative electrode winding section 22in can be a section corresponding to the innermost winding of the negative electrode 22 in the electrode winding body 20. The number of windings of each of the positive electrode 21, the negative electrode 22, and the separator 23 is not particularly limited and can be selected as desired.

[0031] Fig. Figure 4A is an unwound view of the positive electrode 21 and schematically illustrates a state before winding. Fig. Figure 4B shows a section configuration of the positive electrode 21. It should be noted that Fig. 4B a section in the direction of view along the in Fig. The line IVB-IVB shown in Figure 4A is also shown. In some embodiments, the positive electrode 21 can, for example, have a positive electrode current collector 21A and a positive electrode active material layer 21B. In some embodiments, the positive electrode active material layer 21B can cover part of the positive electrode current collector 21A. The positive electrode 21 can further comprise an insulating layer 100. In some embodiments, the positive electrode active material layer 21B and the insulating layer 100 can, for example, be provided only on one of two opposing surfaces of the positive electrode current collector 21A. In some embodiments, the positive electrode active material layer 21B and the insulating layer 100 can, for example, be provided on each of the two opposing surfaces of the positive electrode current collector 21A. Fig. Figure 4B shows a case in which the positive electrode active material layer 21B and the insulating layer 100 are provided on each of the two opposing surfaces of the positive electrode current collector 21A. For example, the positive electrode current collector 21A can have an inner positive electrode current collector surface 21A1 and an outer positive electrode current collector surface 21A2. The inner positive electrode current collector surface 21A1 can be oriented towards a winding center side of the electrode winding body 20, i.e., towards the central axis CL. The outer positive electrode current collector surface 21A2 can be oriented towards a side opposite the winding center side of the electrode winding body 20.In other words, the outer positive electrode current collector surface 21A2 can be located on either side of the positive electrode current collector 21A opposite the inner positive electrode current collector surface 21A1. The positive electrode 21 can have an inner winding-side positive electrode active material layer 21B1 and an outer winding-side positive electrode active material layer 21B2 as positive electrode active material layers 21B. The inner winding-side positive electrode active material layer 21B1 can cover all or part of the inner positive electrode current collector surface 21A1. The outer winding-side positive electrode active material layer 21B2 can cover all or part of the outer positive electrode current collector surface 21A2.Here, the inner winding-side positive electrode active material layer 21B1 and the outer winding-side positive electrode active material layer 21B2 can each be generally referred to as the positive electrode active material layer 21B, without being distinguished from one another. The positive electrode active material layer 21B can extend orthogonally to the L-direction in both the L-direction and the W-direction. The L-direction corresponds to a winding direction of the stack body S20. The W-direction essentially coincides with the central axis CL.

[0032] The positive electrode current collector 21A can correspond to a specific, but not limiting, example of a “first electrode current collector” in an embodiment of the disclosure. The positive electrode active material layer 21B can correspond to a specific, but not limiting, example of a “first electrode active material layer” in an embodiment of the disclosure.

[0033] In some embodiments, the positive electrode 21 can have a positive electrode cover region 211 and a positive electrode exposure region 212. In some embodiments, the positive electrode cover region 211 can be a region in which the positive electrode current collector 21A is covered with the active positive electrode material layer 21B. In some embodiments, the positive electrode exposure region 212 can be a region in which the positive electrode current collector 21A is exposed without being covered with the positive electrode material layer 21B. In some embodiments, the positive electrode exposure region 212 can extend in the W direction. As shown in Fig. As shown in 4A, the positive electrode covering area 211 and the positive electrode exposure area 212 can each extend along the L-direction, i.e. a longitudinal direction of the positive electrode 21, from a winding center side edge 21E1 of the positive electrode 21, i.e. an edge of the positive electrode 21 on the winding center side in the L-direction, to a winding outer circumferential side edge 21E2 of the positive electrode 21, i.e. an edge of the positive electrode 21 on a winding outer circumferential side in the L-direction. Here, the L-direction corresponds to a winding direction of the electrode winding body 20. For example, in the case of the positive electrode 21, the positive electrode current collector 21A can be covered with the positive electrode active material layer 21B in the winding direction of the electrode winding body 20 from the winding center side edge 21E1 of the positive electrode 21 to the winding outer circumferential side edge 21E2 of the positive electrode 21.The positive electrode covering area 211 and the positive electrode exposure area 212 can be adjacent to each other in the W direction, that is, in the transverse direction of the positive electrode 21. The W direction essentially coincides with the central axis CL. The positive electrode active material layer 21B can extend orthogonally to the L direction in both the L and W directions. The L direction corresponds to the longitudinal direction of the positive electrode 21. The W direction corresponds to a lateral direction of the positive electrode 21. As shown in . Fig. As shown in Figure 3, the winding center side edge 21E1 of the electrode winding body 20 can be arranged at a position that is offset inwards relative to a winding center side edge 22E1 of the negative electrode 22, that is, an edge of the negative electrode 22 on the winding center side in the L-direction, at the innermost negative electrode winding section 22in. As shown in Fig. As shown in Figure 4A, the positive electrode 21 can further have a lower edge 21E3 extending in the L-direction along a bottom side of the electrode winding body 20. It should be noted that the Fig. 4A and Fig. Figure 4B schematically shows the positive electrode current collector 21A in a stretched state along the W direction. In reality, however, as shown in Fig. As shown in Figure 1, a positive electrode edge section 212E of the positive electrode exposure area 212 is bent towards the central axis CL and coupled to the positive electrode current collector plate 24. For example, an end section of the positive electrode exposure area 212 in the W direction can form the upper end surface 41 and be coupled to the positive electrode current collector plate 24, as shown in Figure 1. Fig. Figure 1 shows that in some embodiments, the upper end surface 41 can have sections of the positive electrode edge section 212E of the positive electrode exposure area 212, which are bent towards the through-hole 26 in a wound state. The positive electrode edge section 212E can have several parts that are adjacent to each other in a radial direction, i.e., an R-direction, of the electrode winding body 20, and at least one or more of the sections can be bent towards the through-hole 26.

[0034] The positive electrode covering area 211 can correspond to a specific, but not limiting, example of a “first electrode covering area” in an embodiment of the disclosure. The positive electrode exposure area 212 can correspond to a specific, but not limiting, example of a “first electrode exposure area” in an embodiment of the disclosure.

[0035] In some embodiments, the insulating layer 100 can be provided in an area encompassing the boundary between the positive electrode cover area 211 and the positive electrode exposure area 212, as well as the vicinity of this boundary. In some embodiments, the insulating layer 100 can also extend, as with the positive electrode cover area 211 and the positive electrode exposure area 212, from the winding center side edge 21E1 to the winding outer circumferential side edge 21E2 in the electrode winding body 20. In some embodiments, the insulating layer 100 can adhere to the first separator element 23A, the second separator element 23B, or both. One reason for this is to prevent misalignment or misalignment between the positive electrode 21 and the separator 23. In some embodiments, the insulating layer 100 can comprise a resin containing polyvinylidene fluoride (PVDF).One reason for this is that if the insulating layer 100 contains PVDF, the insulating layer 100 swells, for example, due to a solvent contained in the electrolyte solution, causing the insulating layer 100 to adhere well to the separator 23.

[0036] Fig. Figure 5A is an unwound view of the negative electrode 22 and schematically illustrates a state before winding. Fig. Figure 5B shows a cross-sectional configuration of the negative electrode 22. It should be noted that Fig. 5B a cut in the direction of view along the in Fig. The line VB-VB shown in Figure 5A is shown. In some embodiments, the negative electrode 22 can, for example, have a negative electrode current collector 22A and a negative electrode active material layer 22B. In some embodiments, the negative electrode active material layer 22B can cover part of the negative electrode current collector 22A. In some embodiments, the negative electrode active material layer 22B can, for example, be provided only on one of two opposing surfaces of the negative electrode current collector 22A. In some embodiments, the negative electrode active material layer 22B can, for example, be provided on each of the two opposing surfaces of the negative electrode current collector 22A.

[0037] Fig. Figure 5B shows an exemplary case in which the negative electrode active material layer 22B is provided on each of the two opposing surfaces of the negative electrode current collector 22A. For example, the negative electrode current collector 22A can have an inner negative electrode current collector surface 22A1 oriented towards the central axis CL and an outer negative electrode current collector surface 22A2 located on one side opposite the inner negative electrode current collector surface 22A1. The negative electrode 22 can have an inner winding-side negative electrode active material layer 22B1 and an outer winding-side negative electrode active material layer 22B2 as negative electrode active material layers 22B. The inner winding-side negative electrode active material layer 22B1 can cover all or part of the inner negative electrode current collector surface 22A1.The outer winding-side negative electrode active material layer 22B2 can cover all or part of the outer negative electrode current collector surface 22A2. Herein, the inner winding-side negative electrode active material layer 22B1 and the outer winding-side negative electrode active material layer 22B2 can each be generally referred to as the negative electrode active material layer 22B, without being distinguished from one another.

[0038] The negative electrode current collector 22A can correspond to a specific, but not limiting, example of a “second electrode current collector” in an embodiment of the disclosure. The negative electrode active material layer 22B can correspond to a specific, but not limiting, example of a “second electrode active material layer” in an embodiment of the disclosure.

[0039] In some embodiments, the negative electrode 22 can have a negative electrode cover region 221 and a negative electrode exposure region 222. The negative electrode cover region 221 can be a region in which the negative electrode current collector 22A is covered with the negative electrode active material layer 22B. The negative electrode exposure region 222 can be a region in which the negative electrode current collector 22A is exposed without being covered with the negative electrode active material layer 22B. As in Fig. As shown in Figure 5A, the negative electrode cover area 221 and the negative electrode exposure area 222 can each extend along the L-direction. The negative electrode exposure area 222 can extend in the winding direction of the electrode winding body 20 from the winding center side edge 22E1 of the negative electrode 22 to an outer circumferential side edge 22E2 of the negative electrode 22, that is, an edge of the negative electrode 22 on the outer circumferential side of the winding. In contrast, the negative electrode cover area 221 can be provided neither at the winding center side edge 22E1 nor at the outer circumferential side edge 22E2 of the negative electrode 22. As shown in Fig. As shown in Figure 5A, sections of the negative electrode exposure area 222 can be provided such that the negative electrode cover area 221 is arranged between them in the L-direction. For example, the negative electrode exposure area 222 can have a first section 222A, a second section 222B, and a third section 222C. The negative electrode 22 can further have a lower edge 22E3 extending in the L-direction on the underside of the electrode winding body 20. The first section 222A can be arranged adjacent to the negative electrode cover area 221 in the W-direction and can extend in the L-direction from the winding center side edge 22E1 of the negative electrode 22 to the winding outer circumferential side edge 22E2 of the negative electrode 22. For example, the first section 222A can be an area extending in the W direction from the negative electrode active material layer 22B.The second section 222B and the third section 222C can be provided such that the negative electrode cover region 221 is located between them in the L-direction. The first section 222A can be located in a region that includes the lower edge 22E3 and its surroundings in the negative electrode 22. For example, the second section 222B can be located in a region that includes the winding center side edge 22E1 and its surroundings in the negative electrode 22, and the third section 222C can be located in a region that includes the winding outer circumferential side edge 22E2 and its surroundings in the negative electrode 22. It should be noted that... Fig. 5A and Fig. Figure 5B schematically shows the negative electrode current collector 22A in the extended state along the W direction. In fact, however, as shown in Fig. As shown in Figure 1, a negative electrode edge section 222E of the negative electrode exposure area 222 is bent towards the central axis CL and coupled to the negative electrode current collector plate 25. For example, an end section of the negative electrode exposure area 222 in the W direction can form the lower end surface 42 and be coupled to the negative electrode current collector plate 25, as shown in Figure 1. Fig. Figure 1 shows that in some embodiments, the lower end surface 42 can have sections of the negative electrode edge section 222E of the negative electrode exposure area 222, which are bent towards the through-hole 26 in a wound state. The negative electrode edge section 222E can have several sections that are adjacent to each other in the radial direction, i.e., in the R-direction, of the electrode winding body 20, and at least one or more of the sections can be bent towards the through-hole 26.

[0040] The negative electrode covering area 221 can correspond to a specific, but not limiting, example of a “second electrode covering area” in an embodiment of the disclosure. The negative electrode exposure area 222 can correspond to a specific, but not limiting, example of a “second electrode exposure area” in an embodiment of the disclosure.

[0041] In the stacking body S20 of the electrode winding body 20, the positive electrode 21 and the negative electrode 22 can be stacked on top of each other with the separator 23 interposed, such that the positive electrode exposure area 212 and the first section 222A of the negative electrode exposure area 222 point in opposite directions along the W-direction, i.e., the width direction. In the electrode winding body 20, an end section of the separator 23 can be attached to a side surface section 45 of the electrode winding body 20 by attaching a fastening band 46, thereby preventing the winding from coming loose.

[0042] In some embodiments, such as in Fig. As shown in Figure 2, the secondary battery 1 can satisfy A > B, where A is a width of the positive electrode exposure area 212, and B is a width of the first section 222A of the negative electrode exposure area 222. For example, if the width A is 7 mm, the width B can be 4 mm. In some embodiments, the secondary battery 1 can satisfy C > D, where C is a width of a section of the positive electrode exposure area 212 projecting from an outer edge in the width direction of the separator 23, and D is a length of a section of the first section 222A of the negative electrode exposure area 222 projecting from an opposite outer edge in the width direction of the separator 23. For example, if the width C is 4.5 mm, the width D can be 3 mm.

[0043] As in Fig. As shown in Figure 1, in the upper part of the secondary battery 1, several sections of the positive electrode edge section 212E of the positive electrode exposure area 212 wound around the central axis CL, which are adjacent to each other in the radial direction, i.e., in the R-direction, of the electrode winding body 20, can be bent towards the central axis CL such that they overlap each other. The sections of the positive electrode edge section 212E can thus form the upper end surface 41 of the electrode winding body 20. Similarly, in the lower part of the secondary battery 1, several sections of the negative electrode edge section 222E of the negative electrode exposure area 222 wound around the central axis CL, which are adjacent to each other in the radial direction, i.e., in the R-direction, can be bent towards the central axis CL such that they overlap each other.The sections of the negative electrode edge section 222E can thus form the lower end surface 42 of the electrode winding body 20. Accordingly, the sections of the positive electrode edge section 212E of the positive electrode exposure area 212 can accumulate at the upper end surface 41 of the electrode winding body 20, and the sections of the negative electrode edge section 222E of the negative electrode exposure area 222 can accumulate at the lower end surface 42 of the electrode winding body 20. To achieve better contact between the positive electrode current collector plate 24 for current extraction and the positive electrode edge section 212E, the sections of the positive electrode edge section 212E that are curved towards the central axis CL can form a flat surface.Similarly, to achieve better contact between the negative electrode current collector plate 25 for current extraction and the negative electrode edge section 222E, the sections of the negative electrode edge section 222E curved towards the central axis CL can form a flat surface. It should be noted that the term "flat surface" used herein can encompass not only a completely flat surface, but also a surface with some irregularities or surface roughness to such an extent that the positive electrode exposure area 212 can be connected to the positive electrode current collector plate 24 and the negative electrode exposure area 222 can be connected to the negative electrode current collector plate 25.

[0044] The positive electrode current collector 21A can comprise an electrically conductive foil, such as an aluminum foil, as described later. The negative electrode current collector 22A can comprise an electrically conductive foil, such as a copper foil, as described later. In this case, the positive electrode current collector 21A can be softer than the negative electrode current collector 22A. For example, the positive electrode exposure area 212 can have a lower modulus of elasticity than the negative electrode exposure area 222. Accordingly, in some embodiments, the secondary battery 1 can satisfy both A > B and C > D with respect to the widths A to D.In such a case, if the positive electrode exposure area 212 and the negative electrode exposure area 222 are bent substantially simultaneously with substantially equal pressures from both electrode sides, the bent section in the positive electrode 21 and the bent section in the negative electrode 22 may sometimes become substantially equal in height, as measured from the respective ends of the separator 23. In this case, the sections of the positive electrode edge section 212E, shown in . Fig. 1. overlap each other by bending in a suitable manner. This facilitates easy connection of the positive electrode exposure area 212 to the positive electrode current collector plate 24. Similarly, the sections of the negative electrode edge section 222E, shown in Fig. 1. They overlap each other by bending in a suitable manner. This facilitates easy connection of the negative electrode exposure area 222 to the negative electrode current collector plate 25. The term "connection" as used herein may, for example, refer to coupling by laser welding; however, a method of joining is not limited to laser welding. In some embodiments, any other suitable coupling method may be used.

[0045] As in Fig. As shown in Figure 2, a section of the positive electrode exposure area 212 of the positive electrode 21, which is opposite the negative electrode 22 via the separator 23, can be covered with the insulating layer 100. The insulating layer 100 can, for example, have a width of 3 mm in the W direction. The insulating layer 100 can completely cover a section of the positive electrode exposure area 212 of the positive electrode 21, which is opposite the negative electrode cover area 221 of the negative electrode 22 via the separator 23. The insulating layer 100 helps to effectively prevent an internal short circuit of the secondary battery 1 if, for example, foreign matter penetrates between the negative electrode cover area 221 and the positive electrode exposure area 212.Furthermore, when the secondary battery 1 is subjected to an impact, the insulating layer 100 absorbs the impact, thereby helping to effectively prevent, for example, bending of the positive electrode exposure area 212 or a short circuit between the positive electrode exposure area 212 and the negative electrode 22. [Positive electrode current collector 21A]

[0046] The positive electrode current collector 21A can, for example, be made of an electrically conductive material such as aluminum. The positive electrode current collector 21A can, for example, be a metal foil containing a material such as aluminum or an aluminum alloy. [Positive electrode active material layer 21B]

[0047] The positive electrode active material layer 21B can comprise one or more positive electrode materials into which lithium can be deposited and from which lithium can be extracted. In some embodiments, the positive electrode active material layer 21B can further comprise one or more other materials, including, but not limited to, a positive electrode binder and a positive electrode conductor. In some embodiments, the positive electrode material can be a lithium-containing compound. In some embodiments, the lithium-containing compound can be, for example, but not limited to, a lithium-containing composite oxide or a lithium-containing phosphoric acid compound. The lithium-containing composite oxide can be an oxide comprising lithium and one or more other elements, that is, one or more elements other than lithium, as constituent elements.The lithium-containing composite oxide can have any crystal structure, for example, but not limited to, a layered rock salt crystal structure and a spinel crystal structure. The lithium-containing phosphoric acid compound can be a phosphoric acid compound comprising lithium and one or more other elements as constituent elements. The lithium-containing phosphoric acid compound can have a crystal structure such as an olivine crystal structure. In some embodiments, the positive electrode active material layer 21B can comprise at least one of the following as the positive electrode active material: lithium cobalt oxide, lithium nickel cobalt manganese oxide, or lithium nickel cobalt aluminum oxide. The positive electrode binder can, for example, comprise one or more of the following materials, including, but not limited to, synthetic rubber and a polymer compound.Non-restrictive examples of synthetic rubber include styrene-butadiene rubber, fluororubber, and ethylene propylene diene monomer. Non-restrictive examples of polymer compound include polyvinylidene fluoride and polyimide. The positive electrode conductor may, for example, comprise one or more materials, including but not limited to carbon material. Non-restrictive examples of carbon material include graphite, carbon black, acetylene black, and Ketjen black. In some embodiments, the positive electrode conductor may be one of the electrically conductive materials, for example, a metallic material or an electrically conductive polymer. [Negative electrode current collector 22A]

[0048] The negative electrode current collector 22A can, for example, comprise an electrically conductive material such as copper. The negative electrode current collector 22A can, for example, be a metal foil comprising a material such as nickel, a nickel alloy, copper, or a copper alloy. In some embodiments, a surface of the negative electrode current collector 22A can be roughened. One reason for this is that it helps to improve the adhesion of the negative electrode active material layer 22B to the negative electrode current collector 22A through the so-called anchoring effect. In this case, it may be sufficient for the surface of the negative electrode current collector 22A to be roughened at least in a region facing the negative electrode active material layer 22B. Non-restrictive examples of a roughening method may include a method in which microparticles are formed by electrolytic treatment.During electrolytic treatment, microparticles can be formed on the surface of the negative electrode current collector 22A using an electrolytic process in an electrolyzer. This allows the surface of the negative electrode current collector 22A to be given irregularities. A copper foil produced by the electrolytic process can generally be referred to as electrolytic copper foil. [Negative electrode active material layer 22B]

[0049] The negative electrode active material layer 22B can comprise one or more negative electrode materials into which lithium can be deposited and from which lithium can be extracted. In some embodiments, the negative electrode active material layer 22B can further comprise one or more other materials, including, but not limited to, a negative electrode binder and a negative electrode conductor. The negative electrode material can be an electrically conductive material, such as a carbon material. One reason for this is that the carbon material exhibits only a very slight change in its crystal structure at the time of lithium deposition and extraction, thereby enabling a stable high energy density.Another reason is that the carbon material also serves as a negative electrode conductor, which helps to improve the electrical conductivity of the negative electrode active material layer 22B. The carbon material can be, for example, but is not limited to, graphitizable carbon, non-graphitizable carbon, or graphite. In some embodiments, the spacing of a (002) plane of non-graphitizable carbon can be 0.37 nm or more. In some embodiments, the spacing of a (002) plane of graphite can be 0.34 nm or less. Non-restrictive examples of the carbon material include pyrolytic carbon, coke, glassy carbon fibers, a body produced by burning off organic polymer compounds, activated carbon, and carbon blacks. Non-restrictive examples of coke include pitch coke, needle coke, and petroleum coke.The body produced by burning out organic polymer compounds can be the result of burning out or carbonizing a polymer compound, such as a phenolic resin or a furan resin, at a suitable temperature. In some embodiments, the carbon material can be low-crystalline carbon that has been heat-treated at a temperature of approximately 1000°C or less. In some embodiments, the carbon material can be amorphous carbon. In some embodiments, the carbon material can have a fibrous, spherical, granular, or flaky shape.In secondary battery 1, if the open-circuit voltage in a fully charged state (i.e., the battery voltage) is 4.25 V or higher, the amount of deposited lithium per unit mass can increase compared to an open-circuit voltage of 4.20 V in a fully charged state, even with the same amount of positive electrode active material. The amount of positive electrode active material and the amount of negative electrode active material can therefore be adjusted accordingly. This contributes to achieving a high energy density.

[0050] In some embodiments, the negative electrode active material layer 22B can comprise a silicon-containing material comprising at least one of silicon, silicon oxide, a carbon-silicon compound, or a silicon alloy. The term "silicon-containing material" can be a collective term for any material containing silicon as a constituent element. In some embodiments, the silicon-containing material may comprise only silicon as a constituent element. In some embodiments, only one type of silicon-containing material may be used. In some embodiments, two or more types of silicon-containing materials may be used.The silicon-containing material may be capable of forming an alloy with lithium and may be: a simple silicon substance; a silicon alloy; a silicon compound; a mixture of two or more of a simple silicon substance, a silicon alloy, or a silicon compound; or a material comprising one or more phases of a simple silicon substance, a silicon alloy, and a silicon compound. The silicon-containing material may be crystalline or amorphous, or may contain both crystalline and amorphous components. It should be noted that the term "simple substance" as used here can only refer to a simple substance in a general sense. In some embodiments, the simple substance may therefore contain a small amount of impurities. In other words, the purity of the simple substance is not necessarily limited to 100%.The silicon alloy may comprise one or more constituent elements besides silicon, including, but not limited to, tin, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony, and chromium. The silicon compound may comprise one or more constituent elements besides silicon, including, but not limited to, carbon and oxygen. In some embodiments, the silicon compound may comprise one or more constituent elements besides silicon from the series of constituent elements described above in relation to the silicon alloy. Non-restrictive examples of the silicon alloy and the silicon compound include SiB4, SiB6, Mg2Si, Ni2Si, TiSi2, MoSi2, CoSi2, NiSi2, CaSi2, CrSi2, Cu3Si, FeSi2, MnSi2, NbSi2, TaSi2, VSi2, WSi2, ZnSi2, SiC, Si3N4, Si2N2O, and SiO.v (where 0 < v ≤ 2). It should be noted that the range of v can be chosen arbitrarily and can, for example, be 0.2 < v < 1.4.

[0051] Fig. Figure 6A is a top view schematically illustrating an exemplary state of the upper end face 41 of the electrode winding body 20 from the perspective of the positive electrode current collector plate 24. The upper end face 41 may have sections of the positive electrode edge section 212E in the W direction of the positive electrode exposure area 212, which, in a state where the stack body S20 is wound, are bent towards the through-hole 26. In some embodiments, as shown in Fig. Figure 6A shows the upper end surface 41 having one or more grooves 41G and a grooveless section 41T. In some embodiments, the one or more grooves 41G can each extend from an outer edge 20PE of the electrode winding body 20 to an inner edge 20IE of the electrode winding body 20. In some embodiments, the grooveless section 41T can be located closer to the positive electrode current collector plate 24 than the one or more grooves 41G. Here, the one or more grooves 41G can each be continuous from the outer edge 20PE to the inner edge 20IE, or they can be discontinuous in the middle. In some embodiments, the one or more grooves 41G can have multiple grooves 41G, and the multiple grooves 41G can each have substantially the same length. In some embodiments, the multiple grooves 41G can each have substantially identical shapes.For example, the multiple grooves 41G can be essentially identical to each other in their top view or section view. Fig. Figure 6A shows an exemplary case in which the upper end surface 41 has eight grooves 41G and eight grooveless sections 41T. In some embodiments, the number of one or more grooves 41G can be 3 or more and 16 or fewer. The eight grooves 41G can extend radially from the through-hole 26 in the center. The grooveless section 41T can be a section of the upper end surface 41 that does not have the grooves 41G. The grooveless section 41T of the upper end surface 41 can be connected to the positive electrode current collector plate 24.

[0052] Fig. Figure 6B is a top view schematically illustrating an exemplary state of the lower end face 42 of the electrode winding body 20 from the perspective of the negative electrode current collector plate 25. The lower end face 42 may have sections of the negative electrode edge section 222E in the W direction of the negative electrode exposure area 222, which, in the state in which the stack body S20 is wound, are bent towards the through-hole 26. In some embodiments, as in Fig. As shown in Figure 6B, the lower end surface 42 can have one or more grooves 42G and a grooveless section 42T. In some embodiments, the one or more grooves 42G can extend from the outer edge 20PE of the electrode winding body 20 to the inner edge 20IE of the electrode winding body 20. In some embodiments, the grooveless section 42T can be located closer to the negative electrode current collector plate 25 than the one or more grooves 42G. Here, the one or more grooves 42G can be continuous from the outer edge 20PE to the inner edge 20IE, or they can be discontinuous in the middle. In some embodiments, the one or more grooves 42G can have multiple grooves 42G, and the multiple grooves 42G can each have substantially the same length. In some embodiments, the multiple grooves 42G can each have substantially identical shapes.For example, the multiple grooves 42G can be essentially identical to each other in their top view or section view. Fig. Figure 6B shows an exemplary case in which the lower end surface 42 has eight grooves 42G and eight grooveless sections 42T. In some embodiments, the number of one or more grooves 42G can be 3 or more and 16 or fewer. The eight grooves 42G can extend radially from the through-hole 26 in the center. The grooveless section 42T can be a section of the lower end surface 42 that does not have the grooves 42G. The grooveless section 42T of the lower end surface 42 can be connected to the negative electrode current collector plate 25. [Insulating tapes 53 and 54]

[0053] In some embodiments, the secondary battery 1 may further comprise insulating tapes 53 and 54 in a gap between the outer packaging container 11 and the electrode winding body 20. The positive electrode exposure area 212, which has sections that converge at the upper end face 41, and the negative electrode exposure area 222, which has sections that converge at the lower end face 42, may be electrical conductors such as exposed metal foils. Accordingly, if the positive electrode exposure area 212 and the negative electrode exposure area 222 are located near the outer packaging container 11, a short circuit between the positive electrode 21 and the negative electrode 22 via the outer packaging container 11 may occur. A short circuit may also occur if the positive electrode current collector plate 24 facing the upper end face 41 comes close to the outer packaging container 11.To address this, in some embodiments the insulating tapes 53 and 54 can be provided as insulating elements. Each of the insulating tapes 53 and 54 can be an adhesive tape comprising a base layer and an adhesive layer provided on a surface of the base layer. The base layer can, for example, contain polypropylene, polyethylene terephthalate, or polyimide. To prevent the capacitance of the electrode winding body 20 from being reduced by the provision of the insulating tapes 53 and 54, the insulating tapes 53 and 54 can be arranged so that they do not overlap with the fastening tape 46 attached to the side surface section 45, and can each have a thickness that is less than or equal to the thickness of the fastening tape 46. [Positive electrode current collector plate 24 and negative electrode current collector plate 25]

[0054] In a typical lithium-ion secondary battery, for example, a lead for current extraction is welded to each of the positive and negative electrodes. However, such a structure increases the internal resistance of the lithium-ion secondary battery, causing it to generate heat and become hot during discharge; therefore, the structure is unsuitable for high-rate discharge. To address this, in the secondary battery 1 according to the present embodiment, the positive electrode current collector plate 24 can be arranged to face the upper end face 41, and the negative electrode current collector plate 25 can be arranged to face the lower end face 42.Furthermore, the positive electrode exposure area 212, which forms the upper end face 41, and the positive electrode current collector plate 24 can be welded together at several points; and the negative electrode exposure area 222, which forms the lower end face 42, and the negative electrode current collector plate 25 can be welded together at several points. This contributes to a reduction in the internal resistance of the secondary battery 1. The upper end face 41 and the lower end face 42, which each have a flat surface as described above, also contribute to the reduced resistance. The positive electrode current collector plate 24 can be arranged between the battery cover 14 and the upper end face 41. The positive electrode current collector plate 24 can, for example, be electrically coupled to the battery cover 14 via the safety valve mechanism 30.The negative electrode current collector plate 25 can be arranged between the bottom section 11B of the outer packaging container 11 and the lower end surface 42. The negative electrode current collector plate 25 can, for example, be electrically coupled to an inner surface of the bottom section 11B of the outer packaging container 11. Fig. Figure 7A is an unfolded view showing a configuration example of the positive electrode current collector plate 24. Fig. Figure 7B is an unfolded view showing a configuration example of the negative electrode current collector plate 25. The positive electrode current collector plate 24 can be a metal plate comprising, for example, but not limited to, aluminum or an aluminum alloy as a single component, or a composite material of aluminum and the aluminum alloy. The negative electrode current collector plate 25 can be a metal plate comprising, for example, but not limited to, nickel, a nickel alloy, copper, or a copper alloy as a single component, or a composite material of two or more of these.

[0055] As in Fig. As shown in Figure 7A, the positive electrode current collector plate 24 can have a fan-shaped section 31 and a ribbon-shaped section 32. The fan-shaped section 31 can have a substantially fan-shaped form. The ribbon-shaped section 32 can have a substantially rectangular form. However, one form of the positive electrode current collector plate 24 is not shown in Figure 7A. Fig. The form shown in Figure 7A is limited and can be chosen arbitrarily. It should be noted that in the secondary battery 1, the positive electrode current collector plate 24, as shown in Figure 7A, is located in the secondary battery 1. Fig. 1 shown, in a state in which the ribbon-shaped section 32 is bent in relation to the fan-shaped section 31, may be contained within the outer packaging can 11. Fig. Figure 7A shows the positive electrode current collector plate 24 in an unbent state. The fan-shaped section 31 can be an adjacent section, which faces and is coupled to the slotless section 41T of the upper end surface 41. The fan-shaped section 31 can have an outer edge, which, for example, has a straight or linear section and a curved section. The fan-shaped section 31 can have an opening 35 near its center. Fig. Figure 7A shows an exemplary case in which the opening 35 has a circular top-view shape or basic shape in a horizontal plane that is orthogonal to the Z-axis direction. The ribbon-shaped section 32 can, for example, be coupled to the linear section of the outer edge of the fan-shaped section 31. The ribbon-shaped section 32 can extend in a direction that intersects the linear section of the fan-shaped section 31. As shown in Fig. As shown in Figure 1, the positive electrode current collector plate 24 in the secondary battery 1 can be provided such that the opening 35 can overlap with the through hole 26 in the Z-axis direction. For example, the opening 35 can be positioned such that it overlaps with part of the upper end surface 41 on the winding center side in the Z-axis direction.

[0056] A hatched section in Fig. 7A represents an insulating section 32A of the ribbon-shaped section 32. The insulating section 32A can be a segment of the ribbon-shaped section 32 and may have insulating tape or insulating material attached to it. A segment of the ribbon-shaped section 32 below the insulating section 32A can be a coupling section 32B, which is to be coupled to a sealing plate that also serves as an external terminal. The sealing plate can be electrically continuous with the battery cover 14. It should be noted that if the secondary battery 1 has a battery structure without a metallic center pin in the through-hole 26, as in Fig. As shown in Figure 1, the probability of the ribbon-shaped section 32 coming into contact with a region of negative electrode potential is low. In some embodiments, the positive electrode current collector plate 24 need not have the insulating section 32A. If the positive electrode current collector plate 24 does not have the insulating section 32A, it is possible to increase the charging and discharging capacity by increasing the width of the positive electrode 21 and the negative electrode 22, respectively, by an amount corresponding to the thickness of the insulating section 32A.

[0057] The in Fig. The negative electrode current collector plate 25 shown in 7B can have a shape similar to the shape of the one in Fig. The negative electrode current collector plate 25 is similar to the positive electrode current collector plate 24 shown in Figure 7A. The negative electrode current collector plate 25 can have a fan-shaped section 33 and a ribbon-shaped section 34. The fan-shaped section 33 can have an essentially fan-shaped form. The ribbon-shaped section 34 can have an essentially rectangular form. However, the shape of the negative electrode current collector plate 25 is not limited to that shown in Figure 7A. Fig. The form shown in 6B is limited and can be chosen arbitrarily. It should be noted that in the secondary battery 1 the negative electrode current collector plate 25, as in Fig. 1 shown, in a state in which the ribbon-shaped section 34 is bent in relation to the fan-shaped section 33, and may be contained within the outer packaging can 11. Fig. Figure 7B shows the negative electrode current collector plate 25 in an unbent state. The fan-shaped section 33 can be an facing section, which is oriented towards and coupled to the slotless section 42T of the lower end surface 42. The fan-shaped section 33 can have an outer edge, which, for example, has a straight or linear section and a curved section. The ribbon-shaped section 34 can, for example, be coupled to the linear section of the outer edge of the fan-shaped section 33. The ribbon-shaped section 34 can extend in a direction that intersects the linear section of the fan-shaped section 33. The ribbon-shaped section 34 of the negative electrode current collector plate 25 can be shorter than the ribbon-shaped section 32 of the positive electrode current collector plate 24 and may not have a section corresponding to the insulating section 32A of the positive electrode current collector plate 24.The ribbon-shaped section 34 can be provided with projections 37, which are shown as circles. The projections 37 can each be round. All or some of the projections 37 can be welded to the bottom section 11B of the outer packaging container 11. In resistance welding, a current can be concentrated on the projections 37, causing the projections 37 to melt and the ribbon-shaped section 34 to the bottom section 11B of the outer packaging container 11. Like the positive electrode current collector plate 24, the negative electrode current collector plate 25 can also have an opening 36 near the center of the fan-shaped section 33. In the secondary battery 1, the negative electrode current collector plate 25 can be provided such that the opening 36 overlaps the through-hole 26 in the Z-axis direction. Fig. Figure 7B shows an exemplary case in which the opening 36 has a circular top view shape or basic shape in a horizontal plane that runs orthogonally to the Z-axis direction.

[0058] The fan-shaped section 31 of the positive electrode current collector plate 24, due to its top-view shape, can only cover a portion of the upper end surface 41. Similarly, the fan-shaped section 33 of the negative electrode current collector plate 25, due to its top-view shape, can only cover a portion of the lower end surface 42. Reasons why the fan-shaped section 31 does not cover the entire upper end surface 41 and the fan-shaped section 33 does not cover the entire lower end surface 42 include, but are not limited to, the following. One reason, for example, is to allow for uniform penetration of the electrolyte solution into the electrode winding body 20 during assembly of the secondary battery 1.In the secondary battery 1 according to the present embodiment, the positive electrode current collector plate 24 can be configured such that the opening 35 overlaps with a portion of the upper end surface 41 on the winding center side in the Z-axis direction. Accordingly, one or more, but not all, of the sections of the positive electrode edge section 212E forming the upper end surface 41 may not be covered by the fan-shaped section 31 of the positive electrode current collector plate 24 and may be exposed relative to the opening 35. The secondary battery 1 can thus have a structure that allows rapid penetration of the electrolyte solution into the electrode winding body 20. Another advantage is that gas generated when the lithium-ion secondary battery enters an abnormally hot or overcharged state can be easily vented. [Separator 23]

[0059] The separator 23 can be arranged between the positive electrode 21 and the negative electrode 22. The separator 23 allows lithium ions to pass through and prevents a short circuit of a current resulting from contact between the positive electrode 21 and the negative electrode 22. The separator 23 can, for example, have one or more types of porous films, each comprising, for example, but not limited to, a synthetic resin or a ceramic. In some embodiments, the separator 23 can, for example, have a stacked film with two or more types of porous films. Non-limiting examples of synthetic resin can include polytetrafluoroethylene, polypropylene, and polyethylene. In some embodiments, the separator 23 can have a base comprising a single-layer porous polyolefin film comprising polyethylene.One reason for this is that it allows for a better high-performance characteristic ("high output characteristic") compared to the stacked film. In some embodiments, when the first separator element 23A and the second separator element 23B of the separator 23 each have a single-layer porous polyolefin film, the single-layer porous polyolefin film can, for example, have a thickness of more than or equal to 10 µm and less than or equal to 15 µm. If the single-layer porous polyolefin film has a thickness of more than or equal to 10 µm, an internal short circuit can be sufficiently avoided. If the single-layer porous polyolefin film has a thickness of less than or equal to 15 µm, a better discharge capacity characteristic can be achieved. In some embodiments, the single-layer porous polyolefin film can, for example, have a surface density of more than or equal to 6.3 g / m². 2and less than or equal to 8.3 g / m² 2 exhibit. If the single-layer porous film with polyolefin has a surface density greater than or equal to 6.3 g / m². 2 If the single-layer porous film with polyolefin has a surface density of less than or equal to 8.3 g / m², an internal short circuit can be sufficiently avoided. 2 exhibiting this characteristic allows for improved discharge capacity.

[0060] In some embodiments, the separator 23 can, for example, comprise a porous film as the base described above and a polymer compound layer provided on one or each of two opposing surfaces of the base. One reason for this is to improve the adhesion of the separator 23 to the respective positive electrode 21 and negative electrode 22, thereby suppressing deformation of the electrode winding body 20. As a result, decomposition of the electrolyte solution is suppressed, and leakage of the electrolyte solution impregnated with the base is also suppressed. This helps to prevent a slight increase in resistance even with repeated charging and discharging and also suppresses swelling of the secondary battery. The polymer compound layer can, for example, comprise a polymer compound such as polyvinylidene fluoride.One reason for this is that the polymer compound, such as polyvinylidene fluoride, exhibits superior physical strength and electrochemical stability. In some embodiments, the polymer compound may be something other than polyvinylidene fluoride. To form the polymer compound layer, for example, a solution in which the polymer compound is dissolved in a solvent, such as an organic solvent, may be applied to the base, after which the base may be dried. In some embodiments, the base may be immersed in the solution and then dried. In some embodiments, the polymer compound layer may include one or more types of insulating particles, such as inorganic particles. Non-restrictive examples of the type of material contained in the inorganic particles may include aluminum oxide and aluminum nitride. [Electrolyte solution]

[0061] The electrolyte solution may comprise a solvent and an electrolyte salt. In some embodiments, the electrolyte solution may further comprise one or more other materials. Non-limiting examples of the other materials may include an additive. The solvent may comprise one or more non-aqueous solvents, including, but not limited to, an organic solvent. An electrolyte solution containing a non-aqueous solvent may be a so-called non-aqueous electrolyte solution. The non-aqueous solvent may, for example, comprise a fluorine compound and a dinitrile compound. The fluorine compound may, for example, comprise at least one of fluorinated ethylene carbonate, trifluorocarbonate, trifluoroethyl methyl carbonate, a fluorinated carboxylic acid ester, or a fluorinated ether.In some embodiments, the non-aqueous solvent may further contain one or more nitrile compounds other than the dinitrile compound. Non-limiting examples of nitrile compounds other than the dinitrile compound include a mononitrile compound and a trinitrile compound. In some embodiments, the dinitrile compound may contain succinonitrile (SN). However, the dinitrile compound is not limited to succinonitrile and may, in some embodiments, be any other dinitrile compound such as adiponitrile.

[0062] The electrolyte salt may, for example, comprise one or more salts, including, but not limited to, a lithium salt. In some embodiments, the electrolyte salt may comprise a salt other than the lithium salt. Non-limiting examples of a salt other than the lithium salt may include a salt of a light metal other than lithium. Non-limiting examples of the lithium salt may include lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium tetraphenylborate (LiB(C6H5)4), lithium methanesulfonate (LiCH3SO3), lithium trifluoromethanesulfonate (LiCF3SO3), lithium tetrachloroaluminate (LiAlCl4), dilithium hexafluorosilicate (Li2SiF6), lithium chloride (LiCl), and lithium bromide (LiBr). In some embodiments, the lithium salt may comprise one or more of LiPF6, LiBF4, LiClO4, or LiAsF6. In some embodiments, the lithium salt can be LiPF6.The electrolyte salt concentration is not particularly limited. In some embodiments, the electrolyte salt concentration can range from 0.3 mol / kg to 3 mol / kg inclusive of the solvent. In some embodiments, if the electrolyte solution contains LiPF6 as the electrolyte salt, the concentration of LiPF6 in the electrolyte solution can range from 1.25 mol / kg to 1.45 mol / kg inclusive. One reason for this is that it helps prevent cycle degradation caused by the consumption or decomposition of the salt during high-load charging, thus improving the high-load cyclability characteristic.In some embodiments, if the electrolyte solution further comprises LiBF4 in addition to LiPF6 as an electrolyte salt, the concentration of LiBF4 in the electrolyte solution can be within a range of 0.001 wt% to 0.1 wt% inclusive. One reason for this is that it helps to more effectively prevent cycle degradation caused by the consumption or decomposition of the salt during high-load-rate charging, and thus contributes to a further improvement in the high-load cycle stability characteristic. [First connecting part 61 and second connecting part 62]

[0063] Fig. Figure 8A shows a configuration example of a first connecting part 61 between the upper end face 41 of the electrode winding body 20 and the positive electrode current collector plate 24 in a plane that is orthogonal to the central axis CL of the electrode winding body 20. As in Fig. As shown in Figure 8A, the fan-shaped section 31 of the positive electrode current collector plate 24 and the upper end surface 41 can be connected to each other by means of one or more first connecting parts 61. The fan-shaped section 31 and the upper end surface 41 can, for example, be joined by welding. Laser welding can be used as the welding process. The laser welding can include scanning and irradiating a contact section between the fan-shaped section 31 and the upper end surface 41 with lasers in order to fusion weld the contact section. In the figure shown in Fig. In the configuration example shown in Figure 8A, a first connecting element 61 is provided in each of the six slotless sections 41T, which are subdivided by eight slots 41G. Each of the six first connecting elements 61 can be a section in which a portion of one of the six slotless sections 41T and a portion of the fan-shaped section 31 of the positive electrode current collector plate 24 are connected. Each of the six first connecting elements 61 can extend in a meandering line. For example, each of the six first connecting elements 61 can extend from the central axis CL, the winding center of the electrode winding body 20, to the outer edge 20PE of the electrode winding body 20, curving alternately to the left and right along the winding direction of the electrode winding body 20.The six first connecting parts 61 can be spaced apart from one another without overlapping. In some embodiments, respective parts of adjacent first connecting parts 61 can be in contact with each other. For example, the six first connecting parts 61 can be adjacent to one another such that they face each other in the radial direction of the electrode winding body 20. The six first connecting parts 61 can, for example, each extend orthogonally to the radial direction of the electrode winding body 20.

[0064] Fig. Figure 8B shows a configuration example of a second connecting part 62 between the lower end face 42 of the electrode winding body 20 and the negative electrode current collector plate 25 in a plane that is orthogonal to the central axis CL of the electrode winding body 20. As in Fig. As shown in Figure 8B, the fan-shaped section 33 of the negative electrode current collector plate 25 and the lower end surface 42 can be connected to each other by means of one or more second connecting parts 62. The fan-shaped section 33 and the lower end surface 42 can, for example, be joined by welding. In the figure shown in Fig. In the configuration example shown in Figure 8B, a second connecting part 62 is provided in each of the six slotless sections 42T, which are subdivided by eight slots 42G. Each of the six second connecting parts 62 can be a section in which a portion of one of the corresponding six slotless sections 42T and a portion of the fan-shaped section 33 of the negative electrode current collector plate 25 are connected. Each of the six second connecting parts 62 can extend in a meandering line. For example, each of the six second connecting parts 62 can extend from the central axis CL, the winding center of the electrode winding body 20, to the outer edge 20PE of the electrode winding body 20, bending alternately to the left and right along the winding direction of the electrode winding body 20.The six second connecting parts 62 can be spaced apart from each other without overlapping. For example, the six second connecting parts 62 can be adjacent to each other such that they face each other in the radial direction of the electrode winding body 20. The six second connecting parts 62 can, for example, each extend orthogonally to the radial direction of the electrode winding body 20.

[0065] Although the first six connecting parts 61 in the in Fig. 8A configuration example shown and the six second connecting parts 62 in the in Fig. While the configuration example shown in Figure 8B may be provided, an embodiment of the disclosure is not limited thereto. In some embodiments, the number of first connecting parts 61 and second connecting parts 62 may each be one or more. In some embodiments, the number of first connecting part 61 and second connecting part 62 may each be three or more. In some embodiments, the number of first connecting part 61 and second connecting part 62 may each be four or more and six or fewer.

[0066] Fig. 9A is an enlarged schematic top view of the first connecting part 61. As in Fig. As shown in Figure 9A, the multiple first connecting parts 61 each have a meandering shape in a top view in a plane that is orthogonal to the through-hole 26. The first connecting parts 61 each have multiple first linear sections 61A and multiple first reversal sections 61B. The first linear sections 61A can be arranged discretely such that they extend along the winding direction (a θ-direction) of the electrode winding body 20, that is, in a direction orthogonal to the radial direction (the R-direction) of the electrode winding body 20, and that they are adjacent to each other in the radial direction (the R-direction) of the electrode winding body 20. The first reversal sections 61B can each be a curved section bent such that it couples two of the first linear sections 61A together. Fig. Figure 9A shows an example in which seven first linear sections 61A1 to 61A7 are provided as first linear sections 61A and six first reversal sections 61B1 to 61B6 as first reversal sections 61B. However, the number of first linear sections 61A is not limited to a specific number, as long as the number is two or more, and the number of first reversal sections 61B is not limited to a specific number, as long as the number is three or more. It should be noted that in some embodiments, the first linear sections 61A and the first reversal sections 61B may each have a constant width 61W.

[0067] In each of the first connecting parts 61, a length 61La is longer than a length 61L1. The length 61L1 is a length in the winding direction (the θ-direction) of the electrode winding body 20 from the first reversal section 61B1, which is the first of the first reversal sections 61B, counted from the winding center of the electrode winding body 20, to or up to the first reversal section 61B2, which is the second of the first reversal sections 61B, counted from the winding center. The length 61La is a length in the winding direction (the θ-direction) of the electrode winding body 20 from a first reversal section 61Ba, which is one of the first reversal sections 61B of the corresponding first connecting part 61, counted from the winding center, to or up to aup to a first reversing section 61B(a + 1), which is an (a + 1)th of the first reversing sections 61B of the corresponding first connecting part 61, counted from the winding center, where the number of first reversing sections 61B is represented by "n", "n" is a natural number, and "a" is a natural number greater than or equal to two and less than "n". For example, each of the in . Fig. Lengths 61L2 to 61L4 shown in 9A are longer than length 61L1.

[0068] In some embodiments, the in Fig. In the configuration example shown in 9A, the first connecting part 61 has a length 61L(a + 1) longer than the length 61La. The length 61La can be a length in the winding direction (the θ-direction) of the electrode winding body 20 from a first reversal section 61B(a - 1), which is an (a - 1)th of the first reversal sections 61B, counted from the winding center of the electrode winding body 20, to or up to the a-th first reversal section 61Ba, counted from the winding center of the electrode winding body 20, and the length 61L(a + 1) can be a length in the winding direction (the θ-direction) of the electrode winding body 20 from the a-th first reversal section 61Ba, counted from the winding center of the electrode winding body 20, to or up to the first reversal section 61B(a + 1), counted from the winding center of the electrode winding body 20, where “a” is a natural number greater than or equal to two and less than or equal to (n - 1). is. For example, in the Fig. In the configuration example of the first connecting part 61 shown in Figure 9A, the length 61L2 can be longer than the length 61L1 (61L1 < 61L2), the length 61L3 can be longer than the length 61L2 (61L2 < 61L3), and the length 61L4 can be longer than the length 61L3 (61L3 < 61L4). For example, in the Fig. In the configuration example shown in 9A of the first connecting part 61, a dimension in the winding direction (the θ direction) of the first connecting part 61 gradually increases from the winding center side to the winding outer circumferential side.

[0069] In some embodiments, the in Fig. In the configuration example of the first connecting part 61 shown in Figure 9A, the ratio 61L(a + 1) / 61La of length 61L(a + 1) to length 61La is essentially equal to the ratio 61L(a + 2) / 61L(a + 1) of length 61L(a + 2) to length 61L(a + 1). The length 61L(a + 2) can be a length in the winding direction (the θ-direction) from the (a + 1)th first reversal section 61B(a + 1) to, or up to, a first reversal section 61B(a + 2) that is an (a + 2)th of the first reversal sections 61B, counted from the winding center. For example, the ratio (61L2) / (61L1) of length 61L2 to length 61L1 may be essentially equal to the ratio (61L3) / (61L2) of length 61L3 to length 61L2, and the ratio (61L3) / (61L2) may be essentially equal to the ratio (61L4) / (61L3) of length 61L4 to length 61L3. In other words, the following may hold: {(61L2 / 61L1)} ≈ {(61L3 / 61L2)} ≈ {(61L4 / 61L3)}.

[0070] Fig. Figure 9B is a sectional view showing a section of the first connecting part 61 and its surroundings. The first connecting part 61 can be a section in which the fan-shaped section 31 of the positive electrode current collector plate 24 and the positive electrode edge section 212E of the positive electrode current collector 21A are connected to each other. In some embodiments, as in Fig. As shown in Figure 9B, each of the distances 61D1 to 61D6 in the radial direction (the R-direction) of the first linear sections 61A can be shorter than each of the lengths 41D1 to 41D5 in the radial direction (the R-direction) of the sections 212E1 to 212E5 of the positive electrode edge section 212E, which form the upper end face 41. In such a configuration, each of the wound sections of the electrode winding body 20 wound around the central axis CL can be connected to the fan-shaped section 31 of the positive electrode current collector plate 24. For example, the positive electrode edge section 212E of the positive electrode current collector 21A and the fan-shaped section 31 of the positive electrode current collector plate 24 can be connected to each other at a larger number of points or positions, which allows for improved current extraction from the electrode winding body 20.

[0071] The second connecting part 62 can have essentially the same configuration as the first connecting part 61. Fig. 10A is an enlarged schematic top view of the second connecting part 62. In some embodiments, as in Fig. As shown in Figure 10A, the multiple second connecting parts 62 can each have a meandering shape in a top view in a plane that is orthogonal to the through-hole 26. In some embodiments, the second connecting parts 62 can each have multiple second linear sections 62A and multiple second reversing sections 62B. The second linear sections 62A can be arranged discretely such that they extend along the winding direction (the θ-direction) of the electrode winding body 20 and are adjacent to each other in the radial direction (the R-direction) of the electrode winding body 20. The second reversing sections 62B can each be a curved section bent such that it couples two of the second linear sections 62A together. Fig. Figure 10A shows an example in which seven second linear sections 62A1 to 62A7 are provided as second linear sections 62A and six second reversing sections 62B1 to 62B6 are provided as second reversing sections 62B. However, the number of second linear sections 62A is not limited to a specific number, as long as the number is two or more, and the number of second reversing sections 62B is not limited to a specific number, as long as the number is three or more. It should be noted that in some embodiments, the second linear sections 62A and the second reversing sections 62B may each have a constant width 62W.

[0072] In some embodiments, a length 62Lb in each of the second connecting parts 62 can be greater than a length 62L1. The length 62L1 can be a length in the winding direction (the θ-direction) of the electrode winding body 20 from the second reversing section 62B1, which is the first of the second reversing sections 62B, counted from the winding center of the electrode winding body 20, to or up to the second reversing section 62B2, which is the second of the second reversing sections 62B, counted from the winding center. The length 62Lb can be a length in the winding direction (the θ-direction) of the electrode winding body 20 from a first reversing section 62Bb, which is a b-th reversing section of the second reversing sections 62B of the corresponding second connecting part 62, counted from the winding center.up to a second reversing section 62B(b + 1), which is a (b + 1)th reversing section of the second reversing sections 62B of the corresponding second connecting part 62, counted from the winding center, where the number of second reversing sections 62B is represented by "m", "m" is a natural number, and "b" is a natural number greater than or equal to two and less than "m". For example, each of the in . Fig. Lengths 62L2 to 62L4 shown in 10A are longer than length 62L1.

[0073] In some embodiments, the in Fig. In the configuration example shown in 10A, the second connecting part 62 has a length 62L(b + 1) longer than the length 62Lb. The length 62Lb can be a length in the winding direction (the θ-direction) of the electrode winding body 20 from a second reversal section 62B(b - 1), which is a (b - 1)th of the second reversal sections 62B, counted from the winding center of the electrode winding body 20, to or up to the b-th second reversal section 62Bb, counted from the winding center of the electrode winding body 20, and the length 62L(b + 1) can be a length in the winding direction (the θ-direction) of the electrode winding body 20 from the b-th second reversal section 62Bb, counted from the winding center of the electrode winding body 20, to or up to the second reversal section 62B(b + 1), counted from the winding center of the electrode winding body 20, where “b” is a natural number greater than or equal to two and less than or equal to (m - 1) is. For example, in the Fig. In the configuration example of the second connecting part 62 shown in Figure 10A, the length 62L2 can be longer than the length 62L1 (62L1 < 62L2), the length 62L3 can be longer than the length 62L2 (62L2 < 62L3), and the length 62L4 can be longer than the length 62L3 (62L3 < 62L4). For example, in the Fig. In the configuration example shown in 10A of the second connecting part 62, a dimension in the winding direction (the θ direction) of the second connecting part 62 gradually increases from the winding center side to the winding outer circumferential side.

[0074] In some embodiments, the in Fig. In the configuration example of the second connecting part 62 shown in Figure 10A, the ratio 62L(b + 1) / 62Lb of length 62L(b + 1) to length 62Lb is essentially equal to the ratio 62L(b + 2) / 62L(b + 1) of length 62L(b + 2) to length 62L(b + 1). The length 62L(b + 2) can be a length in the winding direction (the θ-direction) from the (b + 1)th second reversal section 62B(b + 1) to, or up to, a second reversal section 62B(b + 2) that is a (b + 2)th of the second reversal sections 62B, counted from the winding center. For example, the ratio (62L2) / (62L1) of length 62L2 to length 62L1 may be essentially equal to the ratio (62L3) / (62L2) of length 62L3 to length 62L2, and the ratio (62L3) / (62L2) may be essentially equal to the ratio (62L4) / (62L3) of length 62L4 to length 62L3. In other words, the following may hold: {(62L2 / 62L1)} ≈ {(62L3 / 62L2)} ≈ {(62L4 / 62L3)}.

[0075] Fig. Figure 10B is a sectional view showing a section of the second connecting part 62 and its surroundings. The second connecting part 62 can be a section in which the fan-shaped section 33 of the negative electrode current collector plate 25 and the negative electrode edge section 222E of the negative electrode current collector 22A are connected to each other. In some embodiments, as in Fig. As shown in Figure 10B, each of the distances 62D1 to 62D6 in the radial direction (the R-direction) of the second linear sections 62A can be shorter than each of the lengths 42D1 to 42D5 in the radial direction (the R-direction) of the sections 222E1 to 222E5 of the negative electrode edge section 222E, which form the lower end surface 42. In such a configuration, each of the wound sections of the electrode winding body 20 wound around the central axis CL can be connected to the fan-shaped section 33 of the negative electrode current collector plate 25. For example, the negative electrode edge section 222E of the negative electrode current collector 22A and the fan-shaped section 33 of the negative electrode current collector plate 25 can be connected to each other at a larger number of points or positions, which allows for improved current extraction from the electrode winding body 20. [1-2. Operation]

[0076] In the secondary battery 1 according to the present embodiment, for example, during charging, lithium ions can be released from the positive electrode 21, and the released lithium ions can be incorporated into the negative electrode 22 via the electrolyte solution. Similarly, in the secondary battery 1, for example, during discharging, lithium ions can be released from the negative electrode 22, and the released lithium ions can be incorporated into the positive electrode 21 via the electrolyte solution. [1-3. Manufacturing processes]

[0077] A method for manufacturing the secondary battery 1 is described with reference to Fig. 11A to Fig. 11F as well Fig. 1 to Fig. 10B described. Fig. 11A to Fig. 11F are each a perspective view depicting a manufacturing process of the in Fig. Secondary battery 1 is described in section 1.

[0078] First, the positive electrode current collector 21A can be provided, and the positive electrode active material layer 21B can be selectively formed on one or each of the two opposing surfaces of the positive electrode current collector 21A. Then, the insulating layer 100 can be formed on the surface of the positive electrode current collector 21A, along an edge of the positive electrode active material layer 21B. In this way, the positive electrode 21 can be obtained by the operation described above. Afterward, the negative electrode current collector 22A can be provided, and the negative electrode active material layer 22B can be selectively formed on one or each of the two opposing surfaces of the negative electrode current collector 22A, thereby forming the negative electrode 22, including the negative electrode cover region 221 and the negative electrode exposure region 222.In some embodiments, the positive electrode 21 and the negative electrode 22 can be subjected to a drying process. Afterwards, the positive electrode 21 and the negative electrode 22 can be stacked, with the first separator element 23A and the second separator element 23B being arranged on the positive electrode 21 and the negative electrode 22, respectively, to ensure that the positive electrode exposure area 212 and the first section 222A of the negative electrode exposure area 222 are located on opposite sides in the W direction. In this way, the stack body S20 can be produced. The stack body S20 can then be wound spirally to form the through-hole 26. For example, a circular columnar winding jig can be used as a tool for winding the stack body S20, and the stack body S20 can be wound around the circular columnar winding jig.Furthermore, the fastening strap 46 can be attached to an outermost winding of the spirally wound stack body S20, after which the winding core can be removed. In this way, the electrode winding body 20 can be removed, as shown in . Fig. 11A is shown, manufactured.

[0079] Subsequently, a section of the upper end face 41 and a section of the lower end face 42 of the electrode winding body 20 can each be locally bent by pressing one end, for example, of a plate-shaped element with a wedge-shaped cross-section, against each of the upper end face 41 and the lower end face 42 perpendicularly, that is, in the Z-axis direction. This process can be referred to as the first pressing or pressing. As a result, the multiple grooves 41G can be formed on the upper end face 41 and the multiple grooves 42G on the lower end face 42. It should be noted that the in Fig. The number and arrangement of the slots 41G shown in Figure 11B are merely examples, and an embodiment of the disclosure is not limited thereto. In some embodiments, the number of slots 41G can be any other number, and the slots 41G can be arranged in any other way.

[0080] Subsequently, essentially equal pressures can be applied essentially simultaneously from above and below perpendicularly to the upper end surface 41 and the lower end surface 42 of the electrode winding body 20, respectively. This process can be described as a second pressing or compression. At this point, for example, a rod-shaped tool can be pre-inserted into the through-hole 26. Through this operation, as described in Fig. As shown in Figure 11C, the positive electrode exposure area 212 can be bent to make a section of the upper end surface 41 a flat surface, thereby forming the slotless section 41T, which is shown in Fig. 1 is not shown, and the first section 222A of the negative electrode exposure area 222 can be bent to make a section of the lower end surface 42 a flat surface, thereby forming the slotless section 42T, which is shown in Fig. Figure 1 is not shown. In some embodiments, at this point, the sections of the positive electrode edge section 212E of the positive electrode exposure area 212 adjacent to each other in the radial direction of the electrode winding body 20 can be bent towards the through-hole 26 at the upper end surface 41 such that they overlap. Similarly, in some embodiments, the sections of the negative electrode edge section 222E of the negative electrode exposure area 222 adjacent to each other in the radial direction of the electrode winding body 20 can be bent towards the through-hole 26 at the lower end surface 42 such that they overlap.The fan-shaped section 31 of the positive electrode current collector plate 24 can then be joined to the slotless section 41T of the upper end surface 41 by a process such as laser welding, and the fan-shaped section 33 of the negative electrode current collector plate 25 can be joined to the slotless section 42T of the lower end surface 42 by a process such as laser welding. This allows the first connecting part 61 and the second connecting part 62 to be formed.

[0081] The insulating tapes 53 and 54 can then be applied to the corresponding predetermined positions or locations on the electrode winding body 20. Then, as described in Fig. As shown in Figure 11D, the ribbon-shaped section 32 of the positive electrode current collector plate 24 can be bent and guided through a hole 12H in the insulating plate 12. Furthermore, the ribbon-shaped section 34 of the negative electrode current collector plate 25 can be bent and guided through a hole 13H in the insulating plate 13.

[0082] The electrode winding body 20, assembled in the manner described above, can then be placed in the Fig. The outer packaging container 11, as shown in Figure 11E, is inserted, after which the bottom section 11B of the outer packaging container 11 and the negative electrode current collector plate 25 can be welded together. Then, the narrow section 11S can be formed near the open end section 11N of the outer packaging container 11. Furthermore, the electrolyte solution can be injected into the outer packaging container 11, after which the ribbon-shaped section 32 of the positive electrode current collector plate 24 and the safety valve mechanism 30 can be welded together.

[0083] After that, the outer packaging can 11 can be used, as in Fig. As shown in Figure 11F, the outer packaging can 11 can be sealed using the narrow section 11S, the seal 15, the safety valve mechanism 30, and the battery cover 14. The outer packaging can then be covered with the outer packaging tube 50, using the washer 55 attached to the battery cover 14. The outer packaging tube 50 can then be heated, for example, by applying hot air. This allows the outer packaging tube 50 to shrink and fit tightly against the outer surface of the outer packaging can 11.

[0084] The secondary battery 1 according to the present embodiment can therefore be completed. [1-4. Impact and exemplary effects]

[0085] As described above, in the secondary battery 1 of the present embodiment, the one or more first connecting parts 61 each have a meandering shape in a top view, and the length 61La is longer than the length 61L1. The length 61L1 is the length in the winding direction (the θ-direction) from the first reversing section 61B1, which is the first of the first reversing sections 61B, counted from the winding center of the electrode winding body 20, to the first reversing section 61B2, which is the second of the first reversing sections 61B, counted from the winding center. The length 61La is the length in the winding direction (the θ-direction) from the first reversing section 61Ba, which is the a-th of the first reversing sections 61B of the corresponding first connecting part 61, counted from the winding center.up to the first reversing section 61B(a + 1), which is the (a + 1)th of the first reversing sections 61B of the corresponding first connecting part 61, counted from the winding center. The configuration in which the one or more first connecting parts 61 each have the meander shape in a top view and the length 61La is longer than the length 61L1, contributes to a uniform current draw from the stack body S20 over the entire distance from an innermost winding section to an outermost winding section of the electrode winding body 20, which in turn contributes to achieving a high output. This also helps to prevent a part orA section of the positive electrode active material layer 21B and a section of the negative electrode active material layer 22B of the stacking body S20 are frequently used locally, which in turn helps to suppress local performance degradation of the positive electrode active material layer 21B and the negative electrode active material layer 22B. Accordingly, the secondary battery 1 of the present embodiment contributes to achieving favorable charge and discharge cycle stability characteristics.

[0086] In contrast, a first connecting part 161-1 extends in a secondary battery 101 according to a Fig. The first comparative example shown in Figure 23 is linear in the radial direction (the R-direction). Furthermore, a first connecting part 161-2 in a secondary battery 102 exhibits a linearity in the radial direction (the R-direction) according to a diagram in Figure 23. Fig. 24A and Fig. The second comparative example shown in 24B in a top view has a meander shape; however, length 161L1 and length 161La are the same size. Length 161L1 is a length in the winding direction (the θ-direction) from a first reversal section 161B1, which is the first of the first reversal sections 161B, counted from the winding center of the electrode winding body 20, to or up to a first reversal section 161B2, which is the second of the first reversal sections 161B, counted from the winding center of the electrode winding body 20. Length 161La is a length in the winding direction (the θ-direction) from a first reversal section 161Ba, of the corresponding first connecting part 161-2, which is the a-th of the first reversal sections 161B, counted from the winding center, to or up to a first reversal section 161B(a + 1), of the corresponding first connecting part 161-2, which is the (a + 1)-th of the first reversal sections 161B. from the winding center.This can reduce the density at a position where the positive electrode edge section 212E of the positive electrode current collector 21A and the fan-shaped section 31 of the positive electrode current collector plate 24 are connected, as the electrode winding body 20 moves closer to the outer circumferential side of the winding from the winding center side. This hinders sufficient current extraction from the positive electrode active material layer 21B and the negative electrode active material layer 22B in a section of the wound portion of the electrode winding body 20 located near the outer circumferential side of the winding. Consequently, sufficient power cannot be achieved.Furthermore, the positive electrode active material layer 21B and the negative electrode active material layer 22B are each frequently used in a section of the wound section of the electrode winding body 20, which is located near the winding center, which can accelerate a deterioration of a charge and discharge cycle strength property.

[0087] Furthermore, in the secondary battery 1 of the present embodiment, one or more second connecting parts 62 can also each have the meandering shape in a top view, and the length 62Lb can be longer than the length 62L1. The length 62L1 can be the length in the winding direction (the θ-direction) from the second reversing section 62B1, which is the first of the second reversing sections 62B, counted from the winding center of the electrode winding body 20, to or up to the second reversing section 62B2, which is the second of the second reversing sections 62B, counted from the winding center. The length 62Lb can be the length in the winding direction (the θ-direction) from the second reversing section 62Bb, which is the b-th of the second reversing sections 62B of the corresponding second connecting part 62, counted from the winding center.up to the second reversing section 62B(b + 1), which is the (b + 1)th of the second reversing sections 62B of the corresponding second connecting part 62, counted from the winding center. The configuration in which the one or more second connecting parts 62 each have the meander shape in a top view and the length 62Lb is longer than the length 62L1, contributes to a more uniform current draw from the stack body S20 over the entire distance from the innermost winding section to the outermost winding section of the electrode winding body 20. This contributes to achieving higher performance and more favorable charge and discharge cycle stability characteristics.

[0088] Furthermore, in the secondary battery 1 of the present embodiment, the dimension in the winding direction (the θ-direction) of the first connecting part 61 can gradually increase from the winding center side to the outer circumferential side of the winding, and the dimension in the winding direction (the θ-direction) of the second connecting part 62 can gradually increase from the winding center side to the outer circumferential side of the winding. This contributes to a more uniform current draw from the stack body S20 over the entire length from the innermost winding section to the outermost winding section of the electrode winding body 20. This contributes to achieving even higher performance and even more favorable charge and discharge cycle stability characteristics.

[0089] As described above, the secondary battery 1 contributes to achieving superior performance according to at least one embodiment of the disclosure. [2. Application examples]

[0090] Non-restrictive application examples for the secondary battery 1 according to the exemplary embodiment of the disclosure may be as described below. [2-1. Battery pack]

[0091] Fig. Figure 12 is a block diagram illustrating a circuit configuration example in which the secondary battery 1 is applied to a battery pack 300 according to the exemplary embodiment of the disclosure. The battery pack 300 may comprise a composite battery 301, a switch 304, an outer packaging body 305, a current sensing resistor 307, a temperature sensing device 308, and a processor 310. The switch 304 may include a charge control switch 302a and a discharge control switch 303a. The outer packaging body 305 may contain the composite battery 301.

[0092] The battery pack 300 can have a positive electrode terminal 321 and a negative electrode terminal 322. During charging, the positive electrode terminal 321 and the negative electrode terminal 322 can each be connected to a positive electrode terminal and a negative electrode terminal, respectively, of a charger to perform the charging process. When using an electronic device, the positive electrode terminal 321 and the negative electrode terminal 322 can each be connected to a positive electrode terminal and a negative electrode terminal of the electronic device to perform the discharging process.

[0093] The composite battery 301 can comprise secondary batteries 301a connected in series or in parallel. The secondary battery 1 described above is applicable to each of the secondary batteries 301a. Fig. Figure 12 shows an exemplary case in which six secondary batteries 301a are configured in a two-parallel and three-series (2P3S) circuit; however, the secondary batteries 301a can also be connected in any other way, for example in any n-parallel and m-series circuit, where n and m are integers.

[0094] The switch 304 can include the charge control switch 302a, a diode 302b, the discharge control switch 303a, and a diode 303b, and can be controlled by the processor 310. The diode 302b can have a polarity that is reverse-biased with respect to a charging current flowing in one direction from the positive electrode terminal 321 to the composite battery 301, and forward-biased with respect to a discharge current flowing in one direction from the negative electrode terminal 322 to the composite battery 301. The diode 303b can have a polarity that is forward-biased with respect to the charging current and reverse-biased with respect to the discharge current. Fig. 12. The switch 304 may be provided on a positive side; however, in some embodiments the switch 304 may be provided on a negative side.

[0095] The charge control switch 302a can be controlled by a charge and discharge control processor such that, when the battery voltage reaches an overcharge detection voltage, the charge control switch 302a is switched off to prevent the charging current from flowing through a current path of the composite battery 301. After the charge control switch 302a is switched off, simple discharge via the diode 302b can be enabled. Furthermore, the charge control switch 302a can be controlled by the processor 310 such that, if a large current flows during charging, the charge control switch 302a is switched off to block the charging current flowing through the current path of the composite battery 301.The discharge control switch 303a can be controlled by the processor 310 such that, when the battery voltage reaches an over-discharge detection voltage, the discharge control switch 303a is switched off to prevent the discharge current from flowing through the current path of the composite battery 301. After the discharge control switch 303a is switched off, simple charging via the diode 303b can be enabled. Furthermore, the discharge control switch 303a can be controlled by the processor 310 such that, if a large current flows during discharge, the discharge control switch 303a is switched off to block the discharge current flowing through the current path of the composite battery 301.

[0096] The temperature sensing device 308 can be, for example, but not exclusively, a thermistor. The temperature sensing device 308 can be located near the composite battery 301. The temperature sensing device 308 can measure the temperature of the composite battery 301 and transmit data regarding the measured temperature to the processor 310. A voltage sensing device 311 can measure the voltage of the composite battery 301 and the voltage of each of the secondary batteries 301a contained therein, perform an analog-to-digital conversion of the measured voltages, and transmit data regarding the converted voltages to the processor 310. An ammeter 313 can measure a current using the current sensing resistor 307 and transmit data regarding the measured current to the processor 310.A switching control processor 314 can control the charging control switch 302a and the discharging control switch 303a of the switch 304 based on the voltage data supplied by the voltage detector 311 and the current data supplied by the ammeter 313.

[0097] If the voltage of one of the secondary batteries 301a reaches or falls below the overcharge detection voltage, or reaches or falls below the overdischarge detection voltage, or if a large current suddenly flows, the switching control processor 314 can transmit a control signal to the switch 304 to prevent overcharging, over-discharging, and overcurrent charging and discharging. For example, if the secondary battery is a lithium-ion battery, the overcharge detection voltage can be set to, for example, 4.20 V ± 0.05 V, and the over-discharge detection voltage can be set to, for example, 2.4 V ± 0.1 V.

[0098] Semiconductor switches such as metal-oxide-semiconductor field-effect transistors (MOSFETs) can be used as charge control switches 302a and discharge control switches 303a, for example. In this case, parasitic diodes of the MOSFETs can serve as diodes 302b and 303b. If P-channel field-effect transistors (FETs) are used as charge control switches 302a and discharge control switches 303a, the switching control processor 314 can supply control signals CO and DO, respectively, to a gate of charge control switch 302a and a gate of discharge control switch 303a. If charge control switch 302a and discharge control switch 303a are of the P-channel type, each can be turned on by a gate potential that is lower than a source potential by a predetermined value or more.For example, in normal charging and discharging operation, the control signals CO and DO can be set to a low level to switch on the charging control switch 302a and the discharging control switch 303a.

[0099] For example, in the event of overcharging or over-discharging, the control signals CO and DO can be set to a high level to switch off the charging control switch 302a and the discharging control switch 303a.

[0100] A memory 317 can, for example, include random-access memory (RAM) and read-only memory (ROM). For instance, the memory 317 can include non-volatile memory such as erasable programmable read-only memory (EPROM). Values, including but not limited to numerical values ​​calculated by the processor 310 and an internal resistance value measured during the manufacturing process for each of the secondary batteries 301a, can be pre-stored in an initial state in the memory 317 and overwritten as needed. Furthermore, storing data regarding the full charge capacity of the secondary battery 301a in the memory 317 allows the processor 310, for example, to calculate a remaining capacity.

[0101] A temperature detector 318 can measure a temperature using the temperature sensing device 308, perform charge and discharge control in case of abnormal heat generation, and make a correction in the calculation of the remaining capacity. [2-2. Power storage system]

[0102] The secondary battery 1 described above, according to the exemplary embodiment of the disclosure, can be mounted on or used to supply electrical power to, for example, any equipment, including, but not limited to, electronic equipment, an electric vehicle, an electric aircraft and a power storage device.

[0103] Non-restrictive examples of electronic equipment may include laptop PCs, smartphones, tablet terminals, personal digital assistants (PDAs) as mobile information terminals, mobile phones, portable terminals, cordless phones, portable video recording and playback devices, digital cameras, electronic books, electronic dictionaries, music players, radios, headphones, game consoles, navigation systems, memory cards, pacemakers, hearing aids, power tools, electric razors, refrigerators, air conditioners, televisions, stereo systems, water heaters, microwave ovens, dishwashers, washing machines, dryers, lighting equipment, toys, medical devices, robots, street cleaning machines, traffic lights, and any other electronic equipment to which any embodiment of the disclosure is applicable.

[0104] Non-restrictive examples of electric vehicles may include rail vehicles, golf carts, electric trolleys, electric vehicles including hybrid electric vehicles, and any other electric vehicles to which any embodiment of the disclosure is applicable. The secondary battery 1 may be used as a drive power source or auxiliary power source for any of these electric vehicles. Non-restrictive examples of the power storage devices may include a power storage power source for architectural structures, including residential buildings, or for power generation plants, and any other power storage devices to which any embodiment of the disclosure is applicable. [3. Modification Examples][First Modification Example]

[0105] Next, a secondary battery 1A according to a first modification example of the secondary battery 1 according to the exemplary embodiment described above will be described. Fig. Figure 13A is a top view showing a configuration example of a first connecting part 61-1 between the upper end face 41 of the electrode winding body 20 and the positive electrode current collector plate 24 in the secondary battery 1A. Fig. 13B is an enlarged schematic top view of the in Fig. Figure 13A shows the first connecting part 61-1. With respect to the first connecting part 61 according to the exemplary embodiment described above, an example is shown in which the ratio 61L(a + 1) / 61La of length 61L(a + 1) to length 61La is essentially equal to the ratio 61L(a + 2) / 61L(a + 1) of length 61L(a + 2) to length 61L(a + 1). The length 61L(a + 2) can be the length in the winding direction (the θ-direction) from the (a + 1)th first reversal section 61B(a + 1) to, or up to, the first reversal section 61B(a + 2), measured from the winding center. In contrast, in the first connecting part 61-1 according to the present modification example, the ratio 61L(a + 1) / 61La can differ from the ratio 61L(a + 2) / 61L(a + 1). For example, the ratio (61L3) / (61L2) of length 61L3 to length 61L2 can be greater than the ratio (61L2) / (61L1) of length 61L2 to length 61L1.It should be noted that in the secondary battery 1A, the second connecting part 62 may also have a configuration similar to that of the first connecting part 61-1. [Second modification example]

[0106] Next, a secondary battery 1B according to a second modification example of the secondary battery 1 according to the exemplary embodiment described above will be described. Fig. Figure 14A is a top view showing a configuration example of a first connecting part 61-2 between the upper end face 41 of the electrode winding body 20 and the positive electrode current collector plate 24 in the secondary battery 1B. Fig. 14B is an enlarged schematic top view of the in Fig. The first connecting part 61-2 is shown in Figure 14A. In the first connecting part 61 according to the exemplary embodiment described above, the dimension in the winding direction (the θ-direction) of the first connecting part 61 can gradually increase from the winding center side to the winding outer circumferential side. In contrast, the first connecting part 61-2 can have a section where the length 61La is longer than the length 61L(a + 1). It should be noted that the length 61L1 can be the shortest. For example, in the configuration example of the first connecting part 61-2, the following can be satisfied: 61L1 < 61L6 < 61L2 < 61L7 < 61L5 < 61L3 < 61L4. It should be noted that in the secondary battery 1B, the second connecting part 62 can also have a configuration similar to that of the first connecting part 61-2. [Third modification example]

[0107] Next, secondary batteries 1C-1 and 1C-2 are described according to a third modification example of secondary battery 1 according to the exemplary embodiment described above. Fig. Figure 15A is a top view showing a configuration example of the first connecting part 61 between the upper end face 41 of the electrode winding body 20 and the positive electrode current collector plate 24 in the secondary battery 1C-1 according to a first example of the third modification example. Fig. Figure 15B is a top view showing a configuration example of the first connecting part 61 between the upper end face 41 of the electrode winding body 20 and the positive electrode current collector plate 24 in the secondary battery 1C-2 according to a second example of the third modification example. In the first connecting part 61 according to the exemplary embodiment described above, six first connecting parts 61 may be provided; however, the secondary battery 1C-1 may be provided with four first connecting parts 61, and the secondary battery 1C-2 may be provided with three first connecting parts 61. It should be noted that the secondary batteries 1C-1 and 1C-2 may each have a configuration of the second connecting parts 62 that is similar to that of the first connecting parts 61. [Fourth modification example]

[0108] Next, a secondary battery 1D according to a fourth modification example of the secondary battery 1 according to the exemplary embodiment described above will be described. Fig. Figure 16 is a top view showing a configuration example of the first connecting part 61 between the upper end face 41 of the electrode winding body 20 and the positive electrode current collector plate 24 in the secondary battery 1D according to the fourth modification example. The secondary battery 1D according to the fourth modification example may, for example, be provided with a section extending radially along an end section of the first connecting part 61 on the winding center side. This helps to enlarge the area where the upper end face 41 and the positive electrode current collector plate 24 are connected, even in a narrow area near the opening 35 provided at the center of the fan-shaped section 31 of the positive electrode current collector plate 24.It should be noted that in the secondary battery 1D, the second connecting part 62 may also have a configuration similar to that of the first connecting part 61. [Fifth modification example]

[0109] Next, a secondary battery 1E according to a fifth modification example of the secondary battery 1 according to the exemplary embodiment described above will be described. Fig. Figure 17 is a top view showing a configuration example of the first connecting part 61 between the upper end face 41 of the electrode winding body 20 and the positive electrode current collector plate 24 in the secondary battery 1E according to the fifth modification example. In the secondary battery 1E according to the fifth modification example, the first linear section 61A of the first connecting part 61 may extend not linearly, but in a curve along the winding direction. It should be noted that in the secondary battery 1E, the second connecting part 62 may also have a configuration similar to that of the first connecting part 61. [Sixth modification example]

[0110] Next, a secondary battery 1F according to a sixth modification example of the secondary battery 1 according to the exemplary embodiment described above will be described. Fig. Figure 18 is a top view showing a configuration example of the first connection part 61 between the upper end face 41 of the electrode winding body 20 and the positive electrode current collector plate 24 in the secondary battery 1F according to the sixth modification example. In the secondary battery 1F according to the sixth modification example, a positive electrode current collector plate 24F can be used instead of the positive electrode current collector plate 24. The positive electrode current collector plate 24F can have a circular plate section 241 instead of the fan-shaped section 31 and a ribbon section 242 instead of the ribbon-shaped section 32. The circular plate section 241 of the positive electrode current collector plate 24F can have a top view shape corresponding to the top view shape of the upper end face 41.This contributes to the fact that in the secondary battery 1F, all slotless sections 41T can be connected to the circular plate section 241 of the positive electrode current collector plate 24F by means of the respective first connecting parts 61. Apart from the points described above, the secondary battery 1F can have a configuration that is essentially the same as the configuration of the secondary battery 1C-1 according to the first example of the third modification example, which is shown in . Fig. The 15A shown corresponds to this. Such a configuration of the secondary battery 1F allows for a higher power output than with the secondary battery 1C-1. It should be noted that in the secondary battery 1F, the second connecting part 62 can also have a configuration similar to that of the first connecting part 61. [Seventh modification example]

[0111] Furthermore, as in a secondary battery 1G according to a seventh modification example, the one in Fig. As shown in Figure 19, a positive electrode current collector plate 24G is used, which has only a circular plate section and no ribbon-shaped section. The circular plate section can have a top-view shape corresponding to the top-view shape of the upper end face 41. It should be noted that the positive electrode current collector plate 24G can have the opening 35. This facilitates the connection of all slotless sections 41T to the positive electrode current collector plate 24G in the secondary battery 1G by means of the respective first connecting parts 61. It should be noted that in the secondary battery 1G, the second connecting part 62 can also have a configuration similar to that of the first connecting part 61. [Eighth modification example]

[0112] In one embodiment of the present disclosure, as in a secondary battery 1H according to an eighth modification example, the in Fig. As shown in Figure 20, a positive electrode current collector plate 24H can also be used. The positive electrode current collector plate 24H can only have a circular plate section and can have neither a band-shaped section nor the opening 35. The circular plate section can have a top-view shape corresponding to the top-view shape of the upper end surface 41. This helps to ensure that all slotless sections 41T in the secondary battery 1H can also be connected to the positive electrode current collector plate 24H by means of the respective first connecting parts 61. It should be noted that in the secondary battery 1H, the second connecting part 62 can also have a configuration similar to that of the first connecting part 61. [Ninth modification example]

[0113] In the present disclosure, as in a secondary battery 1I according to a ninth modification example, the in Fig. As shown in Figure 21, a positive electrode current collector plate 24I with a shape other than a circular shape can also be used. It should be noted that in the secondary battery 1I, the second connecting part 62 can also have a configuration similar to that of the first connecting part 61. [Tenth modification example]

[0114] In the present disclosure, as in a secondary battery 1J according to a tenth modification example, the Fig.As shown in Figure 22, the upper end surface 41 of the electrode winding body 20 is provided with a slotless section 41T and without a groove 41G. It should be noted that in the secondary battery 1J, the second connecting part 62 may also have a configuration similar to that of the first connecting part 61.

[0115] For example, the lower end surface 42 of the electrode winding body 20 can be provided with a slotless section 42T and with no slot 42G.

[0116] Although the disclosure has been described above with reference to some exemplary embodiments and modification examples, a configuration of any embodiment of the disclosure is not limited to the configurations described with reference to the exemplary embodiments and modification examples and can therefore be modified in a variety of ways. For example, the above exemplary embodiment described the case in which the electrode reactant is lithium; however, the electrode reactant is not particularly limited. In some embodiments, the electrode reactant may be another alkali metal such as sodium or potassium, as described above. In some embodiments, the electrode reactant may be an alkaline earth metal such as beryllium, magnesium, or calcium, as described above. In some embodiments, the electrode reactant may be another light metal such as aluminum.

[0117] In the secondary battery of an exemplary embodiment of the present disclosure, the length of the first linear section in the first connecting part and the length of the second linear section in the second connecting part are not specifically limited. In some embodiments, if several first connecting parts are provided, their respective shapes and thicknesses may be uniform in all several first connecting parts, or the shapes and thicknesses of one or more of the first connecting parts may differ from the shapes and thicknesses of other first connecting parts. The same may apply to the second connecting parts if several second connecting parts are provided.

[0118] In some embodiments, where multiple first connecting parts are provided, the number of first reversing sections in the respective first connecting parts may differ. The same may apply to the second connecting parts if multiple second connecting parts are provided.

[0119] According to a secondary battery of an exemplary embodiment of the present disclosure, one or more first connecting parts each have a predetermined meander shape in a top view. This helps to ensure that the current is drawn from a stacked body uniformly over the entire distance from an innermost winding section to an outermost winding section of an electrode winding body, which in turn helps to achieve high performance.

[0120] The effects described herein are merely examples, and the effects of any embodiment of the disclosure are therefore not limited to those described herein. Accordingly, any embodiment of the disclosure may produce any other effect.

[0121] Furthermore, the disclosure encompasses any possible combination of some or all of the embodiments and modification examples described herein. It is possible to realize at least the following configurations from the exemplary embodiments of the disclosure described above. (1) Secondary battery comprising: an electrode winding body comprising a stack body and a through-hole, wherein the stack body comprises a first electrode, a second electrode and a separator and is wound along a longitudinal direction of the stack body, the through-hole extending through the electrode winding body in a lateral direction orthogonal to the longitudinal direction; and a first electrode current collector plate and a second electrode current collector plate, which are opposite each other, wherein the electrode winding body is arranged in the width direction between the first electrode current collector plate and the second electrode current collector plate, wherein the electrode winding body has a first end surface and a second end surface, wherein the first end surface faces the first electrode current collector plate in the width direction and the second end surface faces the second electrode current collector plate in the width direction, the first electrode current collector plate and the first end surface are connected to each other by means of one or more first connecting parts, the one or more first connecting parts each have a meander shape in a top view in a plane that is orthogonal to the through-hole, wherein the meander shape has several first linear sections and several first reversal sections, wherein the first linear sections are adjacent to each other in a radial direction of the electrode winding body, wherein the first reversal sections couple the first linear sections together, and in each of the one or more first connecting parts, a length in a winding direction of the electrode winding body from an a-th of the first reversal sections, counted from a winding center of the electrode winding body, to an (a + 1)-th of the first reversal sections, counted from the winding center, is longer than a length in the winding direction from a first of the first reversal sections, of a corresponding first connecting part, counted from the winding center, to a second of the first reversal sections, of a corresponding first connecting part, counted from the winding center, where a number of first reversal sections is represented by "n", "n" is a natural number and "a" is a natural number greater than or equal to two and less than "n". (2) Secondary battery according to (1) wherein in each of the one or more first connecting parts, a second length is longer than a first length, the first length is a length in the winding direction from an (a - 1)-th of the first reversal sections, counted from the winding center, to an a-th of the first reversal sections, counted from the winding center, where “a” is a natural number greater than or equal to two and less than or equal to (n - 1), the second length is a length in the winding direction from the a-th first reversal section to a (a + 1)-th of the first reversal sections, counted from the winding center. (3) Secondary battery according to (2) wherein a ratio of the second length to the first length is essentially equal to a ratio of a third length to the second length, wherein the third length is a length in the winding direction from the (a + 1)th first reversal section to a (a + 2)th of the first reversal sections, counted from the winding center. (4) Secondary battery according to (1) wherein the first electrode comprises a first electrode current collector and a first electrode active material layer, wherein the first electrode active material layer covers part of the first electrode current collector, the first electrode has a first electrode cover area and a first electrode exposure area, wherein the first electrode cover area is an area in which the first electrode current collector is covered with the first electrode active material layer, wherein the first electrode exposure area is adjacent in the width direction to the first electrode cover area and is an area in which the first electrode current collector is exposed without being covered with the first electrode active material layer, wherein the first electrode exposure area is connected to the first electrode current collector plate, the first end surface has sections of a boundary section of the first electrode exposure area that are bent in a wound state, and a distance in the radial direction of the first linear sections is shorter than a length in the radial direction of each of the sections of the edge section of the first electrode exposure area that form the first end surface. (5) Secondary battery according to (4), wherein the first end surface has one or more first grooves and a first grooveless section, wherein the one or more first grooves each extend in the radial direction, wherein the first grooveless section is closer to the first electrode current collector plate than the one or more first grooves, and Each of the one or more first connecting parts is a section in which a part of the first slotless section and a part of the first electrode current collector plate are connected together. (6) Secondary battery according to (1) which have one or more first connecting parts, and the several first connecting parts are spaced apart from each other. (7) Secondary battery according to (1) wherein the number of one or more first connecting parts is three or more. (8) Secondary battery according to (1) the second electrode current collector plate and the second end surface are connected to each other by means of one or more second connecting parts, one or more second connecting parts each have a meander shape in a top view in a plane that is orthogonal to the through-hole, wherein the meander shape has several second linear sections and several second reversal sections, wherein the second linear sections are adjacent to each other in the radial direction, wherein the second reversal sections couple the second linear sections together, and in each of the one or more second connecting parts, a length in the winding direction from a b-th of the second reversal sections, counted from the winding center, to a (b + 1)-th of the second reversal sections, counted from the winding center, is longer than a length in the winding direction from a first of the second reversal sections, a corresponding second connecting part, counted from the winding center, to a second of the second reversal sections, a corresponding second connecting part, counted from the winding center, where a number of second reversal sections is represented by "m", "m" is a natural number and "b" is a natural number greater than or equal to two and less than "m". (9) Secondary battery according to (8) in each of the one or more second connecting parts, a fifth length is longer than a fourth length, the fourth length is a length in the winding direction from a (b - 1)th of the second reversal sections, counted from the winding center, to a bth of the second reversal sections, counted from the winding center, where “b” is a natural number greater than or equal to two and less than or equal to (m - 1), the fifth length is a length in the winding direction from the b-th second reversal section to a (b + 1)-th of the second reversal sections, counted from the winding center. (10) The secondary battery according to (9), wherein a ratio of the fifth length to the fourth length is substantially equal to a ratio of a sixth length to the fifth length, wherein the sixth length is a length in the winding direction from the (b + 1)th second reversal section to a (b + 2)th of the second reversal sections, counted from the winding center. (11) Secondary battery according to (8), wherein the second electrode has a second electrode current collector and a second electrode active material layer, wherein the second electrode active material layer covers part of the second electrode current collector, the second electrode has a second electrode cover area and a second electrode exposure area, wherein the second electrode cover area is an area in which the second electrode current collector is covered with the second electrode active material layer, wherein the second electrode exposure area is adjacent in the width direction to the second electrode cover area and is an area in which the second electrode current collector is exposed without being covered with the second electrode active material layer, wherein the second electrode exposure area is connected to the second electrode current collector plate, the second end surface has sections of a boundary section of the second electrode exposure area that are bent in a wound state, and a distance in the radial direction of the second linear sections is shorter than a length in the radial direction of each of the sections of the edge section of the second electrode exposure area that form the second end surface. (12) Secondary battery according to (11) wherein the second end surface has one or more second grooves and a second grooveless section, wherein the one or more second grooves each extend in the radial direction, wherein the second grooveless section is closer to the second electrode current collector plate than the one or more second grooves, and Each of the one or more second connecting parts is a section in which a part of the second slotless section and a part of the second electrode current collector plate are connected together. (13) Secondary battery according to (8), at which which have one or more second connecting parts, and the several second connecting parts are spaced apart from each other. (14) Secondary battery according to (8), wherein the number of one or more second connecting parts is three or more. (15) Secondary battery according to one of (1) to (14), wherein the first electrode has a positive electrode and the second electrode has a negative electrode. (16) Battery pack comprising: the secondary battery according to one of (1) to (15); a processor configured to control the secondary battery; and an outer packaging body containing the secondary battery.

[0122] According to a secondary battery of at least one embodiment of the disclosure and a battery pack comprising the secondary battery of at least one embodiment of the disclosure, one or more first connecting parts each have a meander shape in a top view, and in each of the one or more first connecting parts, a length in a winding direction of an electrode winding body from a nth of several first reversal sections of a corresponding first connecting part, counted from a winding center of the electrode winding body, to a (a + 1)th of the first reversal sections, counted from the winding center, is longer than a length in the winding direction from a first of the first reversal sections of the corresponding first connecting part, counted from the winding center, to a second of the first reversal sections of the corresponding first connecting part, counted from the winding center.This helps to ensure that the current is drawn from a stacked body evenly over the entire distance from an innermost winding section to an outermost winding section of the electrode winding body, which in turn helps to achieve high power output.

[0123] As described above, the secondary battery according to at least one exemplary embodiment of the disclosure and the battery pack according to at least one embodiment of the disclosure each contribute to achieving superior performance.

[0124] It should be noted that the effects of an embodiment of the disclosure are not necessarily limited to the exemplary effects described above and may include any of the effects described herein in relation to the exemplary embodiments of the disclosure.

[0125] Although the disclosure has been described above with reference to the exemplary embodiment and modification examples, the disclosure is not limited thereto. It is understood that variations to the described exemplary embodiment and the modification examples can be made by those skilled in the art without deviating from the scope of the disclosure as defined by the appended claims.

[0126] The limitations in the claims are to be interpreted broadly, based on the language used in the claims, and are not limited to examples described in this description or during the filing, the examples being to be interpreted as non-exhaustive.

[0127] As used in this description and the attached claims, the singular forms “ein”, “eine” and “der / die / das” are to be interpreted, particularly in the context of the claims, as covering both the singular and the plural, unless otherwise specified herein or clearly excluded by the context.

[0128] In this description and the accompanying claims, the terms “have”, “include”, “have” and their variants, unless the context otherwise requires, are to be interpreted as including the presence of a specified element, integer or step, but not excluding the absence of any other unspecified element, integer or step.

[0129] The use of the terms "first", "second", etc. does not indicate any order or importance, but merely serves to distinguish one element from another.

[0130] The terms “essentially”, “circa”, “about”, and their corresponding variations are defined in such a way as to largely, but not necessarily completely, correspond to what is stated as understood by a person skilled in the art.

[0131] The term “arranged on / intended on / (trained) on” and its corresponding variants, as used herein, refer to elements that are in direct contact with each other or are indirectly connected with intervening structures. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] WO 2021 / 020237

[0003]

Claims

[1] Secondary battery (1) comprising: an electrode winding body (20) comprising a stacking body (S20) and having a through-hole (26), wherein the stacking body comprises a first electrode (21), a second electrode (22) and a separator (23) and is wound along a longitudinal direction (L) of the stacking body, the through-hole extending through the electrode winding body in a lateral direction (W) that is orthogonal to the longitudinal direction; and a first electrode current collector plate (24) and a second electrode current collector plate (25) opposite each other, wherein the electrode winding body is arranged in the width direction between the first electrode current collector plate and the second electrode current collector plate, wherein the electrode winding body has a first end surface (41) and a second end surface (42), wherein the first end surface faces the first electrode current collector plate in the width direction and the second end surface faces the second electrode current collector plate in the width direction, the first electrode current collector plate and the first end surface are connected to each other by one or more first connecting parts, the one or more first connecting parts (61) each have a meander shape in a top view in a plane that is orthogonal to the through-hole, wherein the meander shape has several first linear sections (61A) and several first reversal sections (61B), wherein the first linear sections are adjacent to each other in a radial direction (R) of the electrode winding body, wherein the first reversal sections couple the first linear sections together, and in each of the one or more first connecting parts, a length in a winding direction of the electrode winding body from an a-th of the first reversal sections, counted from a winding center of the electrode winding body, to an (a + 1)-th of the first reversal sections, counted from the winding center, is longer than a length in the winding direction from a first of the first reversal sections, of a corresponding first connecting part, counted from the winding center, to a second of the first reversal sections, of the corresponding first connecting part, counted from the winding center, where a number of first reversal sections is represented by "n", "n" is a natural number and "a" is a natural number greater than or equal to two and less than "n". [2] Secondary battery (1) according to claim 1, wherein in each of the one or more first connecting parts (61) a second length is longer than a first length, the first length is a length in the winding direction from an (a - 1)-th of the first reversal sections (61B), counted from the winding center, to an a-th of the first reversal sections, counted from the winding center, where “a” is a natural number greater than or equal to two and less than or equal to (n - 1), where the second length is a length in the winding direction from the a-th first reversal section to an (a + 1)-th of the first reversal sections, counted from the winding center. [3] Secondary battery (1) according to claim 2, wherein a ratio of the second length to the first length is substantially equal to a ratio of a third length to the second length, wherein the third length is a length in the winding direction from the (a + 1)th first reversing section to a (a + 2)th of the first reversing sections (61B), counted from the winding center. [4] Secondary battery (1) according to claim 1, wherein the first electrode (21) has a first electrode current collector (21A) and a first electrode active material layer (21B), wherein the first electrode active material layer covers part of the first electrode current collector, the first electrode has a first electrode cover area (211) and a first electrode exposure area (212), wherein the first electrode cover area is an area in which the first electrode current collector is covered with the first electrode active material layer, wherein the first electrode exposure area is adjacent in the width direction (W) to the first electrode cover area and is an area in which the first electrode current collector is exposed without being covered with the first electrode active material layer, wherein the first electrode exposure area is connected to the first electrode current collector plate (24), the first end surface (41) has sections (212E1 to 212E5) of an edge section (212E) of the first electrode exposure area which are bent in a wound state, and a distance in the radial direction (R) of the first linear sections (61A) is shorter than a length in the radial direction of each of the sections of the edge section of the first electrode exposure area that form the first end surface. [5] Secondary battery (1) according to claim 4, wherein the first end surface (41) has one or more first grooves (41G) and a first grooveless section (41T), wherein the one or more first grooves each extend in the radial direction (R), the first grooveless section is closer to the first electrode current collector plate (24) than the one or more first grooves, and Each of the one or more first connecting parts (61) is a section in which a part of the first slotless section and a part of the first electrode current collector plate are connected together. [6] Secondary battery (1) according to claim 1, wherein which have one or more first connecting parts (61) and several first connecting parts, and the several first connecting parts are spaced apart from each other. [7] Secondary battery (1) according to claim 1, wherein the number of one or more first connecting parts (61) is three or more. [8] Secondary battery (1) according to claim 1, wherein the second electrode current collector plate (25) and the second end surface (42) are connected to each other by means of one or more second connecting parts (62), one or more second connecting parts each have a meander shape in a top view in a plane that is orthogonal to the through hole (26), wherein the meander shape has several second linear sections (62A) and several second reversal sections (62B), wherein the second linear sections are adjacent to each other in the radial direction (R), wherein the second reversal sections couple the second linear sections together, and in each of the one or more second connecting parts, a length in the winding direction from a b-th of the second reversal sections, counted from the winding center, to a (b + 1)-th of the second reversal sections, counted from the winding center, is longer than a length in the winding direction from a first of the second reversal sections, of the corresponding second connecting parts, counted from the winding center, to a second of the second reversal sections, of the corresponding second connecting parts, counted from the winding center, where a number of second reversal sections is represented by "m", "m" is a natural number and "b" is a natural number greater than or equal to two and less than "m". [9] Secondary battery (1) according to claim 8, wherein in each of the one or more second connecting parts (62) a fifth length is longer than a fourth length, the fourth length is a length in the winding direction from a (b - 1)-th of the second reversal sections (62B), counted from the winding center, to a b-th of the second reversal sections, counted from the winding center, where “b” is a natural number greater than or equal to two and less than or equal to (m - 1), the fifth length is a length in the winding direction from the b-th second reversal section to a (b + 1)-th of the second reversal sections, counted from the winding center. [10] Secondary battery (1) according to claim 9, wherein a ratio of the fifth length to the fourth length is substantially equal to a ratio of a sixth length to the fifth length, wherein the sixth length is a length in the winding direction from the (b + 1)th second reversing section to a (b + 2)th of the second reversing sections (62B), counted from the winding center. [11] Secondary battery (1) according to claim 8, wherein the second electrode (22) has a second electrode current collector (22A) and a second electrode active material layer (22B), wherein the second electrode active material layer covers part of the second electrode current collector, the second electrode has a second electrode cover area (221) and a second electrode exposure area (222), wherein the second electrode cover area is an area in which the second electrode current collector is covered with the second electrode active material layer, wherein the second electrode exposure area is adjacent in the width direction (W) to the second electrode cover area and is an area in which the second electrode current collector is exposed without being covered with the second electrode active material layer, wherein the second electrode exposure area is connected to the second electrode current collector plate (25), the second end surface (42) has sections (222E1 to 222E5) of an edge section (222E) of the second electrode exposure area which are bent in a wound state, and a distance in the radial direction (R) of the second linear sections (62A) is shorter than a length in the radial direction of each of the sections of the edge section of the second electrode exposure area that form the second end surface. [12] Secondary battery (1) according to claim 11, wherein the second end surface (42) has one or more second grooves (42G) and a second grooveless section (42T), wherein the one or more second grooves each extend in the radial direction (R), wherein the second grooveless section is closer to the second electrode current collector plate (25) than the one or more second grooves, and Each of the one or more second connecting parts (62) is a section in which a part of the second slotless section and a part of the second electrode current collector plate are connected together. [13] Secondary battery (1) according to claim 8, wherein which have one or more second connecting parts (62) and several second connecting parts, and the several second connecting parts are spaced apart from each other. [14] Secondary battery (1) according to claim 8, wherein the number of one or more second connecting parts (62) is three or more. [15] Secondary battery (1) according to any one of claims 1 to 14, wherein the first electrode (21) has a positive electrode and the second electrode (22) has a negative electrode. [16] Battery pack comprising: the secondary battery (1) according to any one of claims 1 to 15; a processor (310) configured to control the secondary battery; and an outer packaging body (305) containing the secondary battery.

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