Secondary battery and battery pack

Abstract

To provide a secondary battery excellent in reliability. The secondary battery is provided with an electrode winding body, and a first electrode collector plate and a second electrode collector plate. The electrode winding body winds a laminate including a first electrode, a second electrode, and a separator along a long side direction of the laminate, and has a through-hole that penetrates in a width direction orthogonal to the long side direction. The first electrode collector plate and the second electrode collector plate sandwich the electrode winding body in the width direction and oppose each other. The first electrode collector plate includes an opening at a position coinciding with the through-hole in the width direction. The diameter of the opening is smaller than the diameter of the through-hole.

Description

Technical Field

[0001] This disclosure relates to secondary batteries and battery packs incorporating such secondary batteries. Background Technology

[0002] With the increasing prevalence of mobile phones and other electronic devices, the development of secondary batteries as small, lightweight power sources with high energy density is underway. These secondary batteries feature battery elements housed within an outer packaging component, and various studies have been conducted regarding their structure (see, for example, Patent Document 1).

[0003] Patent document 1 proposes a secondary battery that employs a structure known as a tabless structure to reduce internal resistance and enable charging and discharging with a relatively large current.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2021 / 020237 Summary of the Invention

[0007] Various studies have been conducted to improve the performance of secondary batteries. However, there is room for improvement in the reliability of secondary batteries.

[0008] Therefore, a rechargeable battery with excellent reliability is desired.

[0009] One embodiment of the present disclosure provides a first secondary battery comprising an electrode winding body, a first electrode current collector, and a second electrode current collector. The electrode winding body is formed by winding a laminate including a first electrode, a second electrode, and a separator along the long side direction of the laminate, and has a through hole extending through in the width direction orthogonal to the long side direction. The first electrode current collector and the second electrode current collector sandwich the electrode winding body in the width direction and are positioned opposite each other. The first electrode current collector includes an opening at a position in the width direction coinciding with the through hole. The diameter of the opening is smaller than the diameter of the through hole.

[0010] One embodiment of the second secondary battery disclosed herein includes an electrode winding body, a first electrode current collector, and a second electrode current collector. The electrode winding body is formed by winding a laminate including a first electrode, a second electrode, and a separator along the long side direction of the laminate, and has a through hole extending in the width direction orthogonal to the long side direction. The first electrode current collector and the second electrode current collector sandwich the electrode winding body in the width direction and are positioned opposite each other. A second bending portion is provided at the outer periphery of the first electrode current collector, bending towards the second electrode current collector.

[0011] A third secondary battery according to one embodiment of this disclosure includes an electrode winding body, a first electrode current collector, and a second electrode current collector. The electrode winding body is formed by winding a laminate including a first electrode, a second electrode, and a separator along the long side direction of the laminate, and has a through hole extending in the width direction orthogonal to the long side direction. The first electrode current collector and the second electrode current collector sandwich the electrode winding body and are positioned opposite each other in the width direction. The first electrode has a first electrode current collector, a base coating covering the first electrode current collector, and a first electrode active material layer covering a portion of the base coating. The second electrode has a second electrode current collector and a second electrode active material layer covering the second electrode current collector. In the width direction, the end edge of the first electrode active material layer is located at a position set back from the end edge of the base coating, and the end edge of the second electrode active material layer is located between the end edge of the base coating and the end edge of the first electrode active material layer.

[0012] According to one embodiment of the present disclosure, the first to third secondary batteries can achieve high reliability. Attached Figure Description

[0013] Figure 1 This is a cross-sectional view illustrating a structural example of the vertical cross-sectional structure of a secondary battery along the height direction in one embodiment of the present disclosure.

[0014] Figure 2 It means including Figure 1 A schematic diagram of a structural example of a laminate of positive electrode, negative electrode and separator shown.

[0015] Figure 3 It means Figure 1 A cross-sectional view of a structural example of the horizontal cross-sectional structure of the electrode winding shown.

[0016] Figure 4A yes Figure 1 The diagram shown is a unfolded diagram of the positive electrode.

[0017] Figure 4B yes Figure 1 The cross-sectional view of the positive electrode is shown.

[0018] Figure 5A yes Figure 1 The diagram shown is a unfolded diagram of the negative electrode.

[0019] Figure 5B yes Figure 1 The cross-sectional view of the negative electrode is shown.

[0020] Figure 6A yes Figure 1 The top view of the positive current collector shown.

[0021] Figure 6B yes Figure 1 The top view of the negative current collector shown.

[0022] Figure 7 This is an explanation Figure 1 The diagram shows a three-dimensional representation of the manufacturing process of a secondary battery.

[0023] Figure 8 This is a block diagram illustrating the circuit structure of a battery pack for a secondary battery that utilizes one embodiment of the present disclosure.

[0024] Figure 9A This is a cross-sectional schematic diagram of a portion of the structure representing the positive electrode in method 1-2.

[0025] Figure 9B This is a cross-sectional schematic diagram of a portion of the positive electrode structure representing methods 1-3.

[0026] Figure 9C This is a magnified cross-sectional schematic diagram of the positive electrode active material particles in methods 1-4.

[0027] Figure 10A This is a cross-sectional schematic diagram of a portion of the structure representing the positive electrode of method 2-1-1.

[0028] Figure 10B This is a cross-sectional schematic diagram of a portion of the structure representing the positive electrode of method 2-1-2.

[0029] Figure 10C This is a cross-sectional schematic diagram of a part of the positive electrode structure representing method 2-1-3.

[0030] Figure 10D This is a cross-sectional schematic diagram of a portion of the structure representing the positive electrode of method 2-1-4.

[0031] Figure 11A This is a cross-sectional schematic diagram of a portion of the structure representing the positive electrode in method 2-2-1.

[0032] Figure 11B This is a cross-sectional schematic diagram of a part of the positive electrode structure representing mode 2-2-2.

[0033] Figure 12A This is a cross-sectional schematic diagram of a portion of the structure representing the positive electrode in method 2-3-1.

[0034] Figure 12B This is a cross-sectional schematic diagram of a portion of the positive electrode structure representing method 2-3-2.

[0035] Figure 13 This is a cross-sectional schematic diagram of a portion of the structure of the positive electrode active material layer in representation 2-4.

[0036] Figure 14This is a cross-sectional schematic diagram of the structure of the positive current collector in method 2-6.

[0037] Figure 15 This is an enlarged cross-sectional view of a portion of the structure of the positive electrode in representation 3-1.

[0038] Figure 16A This is an enlarged cross-sectional view of a portion of the structure of the positive electrode in representation 4-1.

[0039] Figure 16B This is an enlarged cross-sectional view of a portion of the structure of the positive electrode in representation 4-2.

[0040] Figure 16C This is an enlarged cross-sectional view of a portion of the structure of the positive electrode in representation 4-3.

[0041] Figure 17 This is an enlarged cross-sectional view of a portion of the structure of the positive electrode in representation 4-4-1.

[0042] Figure 18A This is an enlarged cross-sectional view of a portion of the structure of the positive electrode of representation 4-4-2A.

[0043] Figure 18B This is an enlarged cross-sectional view of a portion of the structure of the positive electrode in representation 4-4-2B.

[0044] Figure 19A This is an enlarged cross-sectional view of a portion of the structure of the positive electrode of representation 4-4-3A.

[0045] Figure 19B This is an enlarged cross-sectional view of a portion of the structure of the positive electrode in representation 4-4-3B.

[0046] Figure 20 This is an enlarged cross-sectional view of a portion of the positive electrode structure representing method 4-5.

[0047] Figure 21A This is an enlarged cross-sectional view of a portion of the positive electrode structure of representation 4-6A.

[0048] Figure 21B This is an enlarged cross-sectional view of a portion of the structure of the positive electrode in representation 4-6B.

[0049] Figure 21C This is an enlarged cross-sectional view of a portion of the positive electrode structure of representation 4-6C.

[0050] Figure 22A This is a planar schematic diagram of the structure of a portion of the positive electrode of method 4-7A.

[0051] Figure 22BThis is a planar schematic diagram of a portion of the structure of the positive electrode in representation 4-7B.

[0052] Figure 23A This is a cross-sectional schematic diagram of a portion of the structure of the electrode winding body in representation 4-8A.

[0053] Figure 23B This is a cross-sectional schematic diagram of a portion of the structure of the electrode winding body, representing method 4-8C.

[0054] Figure 23C This is a cross-sectional schematic diagram of a portion of the structure of the electrode winding body, representing method 4-8C.

[0055] Figure 24 This is an enlarged cross-sectional view of a portion of the structure of the positive electrode in representation 4-9.

[0056] Figure 25 This is an enlarged cross-sectional view of a portion of the structure of the positive electrode in representation 4-10.

[0057] Figure 26 This is an enlarged cross-sectional view of a portion of the structure of the positive electrode in representation 4-11.

[0058] Figure 27 This is an enlarged cross-sectional view of a portion of the structure of the positive electrode in representation 4-13.

[0059] Figure 28A This is an enlarged cross-sectional view of a portion of the structure of the positive electrode in representation 4-14.

[0060] Figure 28B This is a characteristic graph showing the relationship between the presence or absence of a carbon coating and the interfacial resistance between the positive current collector and the positive active material layer.

[0061] Figure 29A This is an enlarged cross-sectional view of a portion of the structure of the electrode winding body, representing method 4-15-1.

[0062] Figure 29B This is an enlarged cross-sectional view of a portion of the structure of the electrode winding body, representing method 4-15-2.

[0063] Figure 29C This is an enlarged cross-sectional view of a portion of the structure of the electrode winding body, representing method 4-15-3.

[0064] Figure 30 These are enlarged cross-sectional views and planar schematic diagrams of the positive electrode structure in representation 4-16.

[0065] Figure 31 This is a schematic diagram showing the positive electrode active material particles and polyvinylidene fluoride contained in the positive electrode active material layer of method 5-1.

[0066] Figure 32 This is a schematic diagram representing the positive electrode of method 5-2, as well as the positive electrode active material particles and polyvinylidene fluoride contained in the positive electrode active material layer.

[0067] Figure 33 This is a cross-sectional schematic diagram of the positive electrode in method 5-3.

[0068] Figure 34 This is a cross-sectional schematic diagram of the positive electrode in method 5-4.

[0069] Figure 35 This is a cross-sectional schematic diagram of the electrode winding body representing method 5-5.

[0070] Figure 36 This is a cross-sectional schematic diagram of the electrode winding body representing method 5-6.

[0071] Figure 37A This is a cross-sectional schematic diagram of the positive electrode in method 5-7-1.

[0072] Figure 37B This is a cross-sectional schematic diagram of the positive electrode in method 5-7-2.

[0073] Figure 38A This is a cross-sectional schematic diagram of the electrode winding body representing method 5-8.

[0074] Figure 38B This is a top view showing the positive electrode unfolded in the electrode winding body of method 5-8.

[0075] Figure 39 This is a cross-sectional schematic diagram of the electrode winding body representing method 5-9.

[0076] Figure 40A This is a schematic diagram showing the negative electrode active material particles and the porous CMC contained in the negative electrode active material layer of method 6-1.

[0077] Figure 40B It is a magnified microscopic photograph showing the negative electrode active material particles and the porous CMC contained in the negative electrode active material layer of Method 6-2.

[0078] Figure 40C This is a cross-sectional schematic diagram of the negative electrode in representation 6-3.

[0079] Figure 41 This is a cross-sectional schematic diagram of the electrode winding body representing method 7-1.

[0080] Figure 42 This is a cross-sectional schematic diagram of the electrode winding body representing method 7-4.

[0081] Figure 43AThis is a magnified cross-sectional view of the upper end of the electrode winding in the height direction of method 7-6.

[0082] Figure 43B This is a magnified cross-sectional view of the lower end of the electrode winding in the height direction of method 7-6.

[0083] Figure 44 This is a cross-sectional schematic diagram near the upper end face of the electrode winding body in the secondary battery of representation 8-2.

[0084] Figure 45A This is a cross-sectional schematic diagram near the upper end face of the electrode winding body in the secondary battery represented by method 8-3-1.

[0085] Figure 45B This is a cross-sectional schematic diagram near the upper end face of the electrode winding body in the secondary battery represented by method 8-3-2.

[0086] Figure 45C This is a cross-sectional schematic diagram near the upper end face of the electrode winding in a secondary battery, representing method 8-3-3.

[0087] Figure 45D This is a cross-sectional schematic diagram near the upper end face of the electrode winding body in the secondary battery represented by method 8-3-4.

[0088] Figure 46A This is a cross-sectional schematic diagram near the upper end face of the electrode winding body in the secondary battery represented by method 8-4-1.

[0089] Figure 46B This is a cross-sectional schematic diagram near the upper end face of the electrode winding in the secondary battery represented by method 8-4-2.

[0090] Figure 46C This is a cross-sectional schematic diagram near the upper end face of the electrode winding body in a secondary battery representing method 8-4-3.

[0091] Figure 47A This is a cross-sectional schematic diagram near the upper end face of the electrode winding body in a secondary battery representing method 8-5-1.

[0092] Figure 47B This is a cross-sectional schematic diagram near the upper end face of the electrode winding body in the secondary battery represented by method 8-5-2.

[0093] Figure 48 This is a planar schematic diagram of the electrode winding body and the positive electrode current collector in a secondary battery representing method 8-6.

[0094] Figure 49A This is a planar schematic diagram showing the unfolded state of the electrode winding body in mode 10-3-1.

[0095] Figure 49B This is a planar schematic diagram showing the unfolded state of the electrode winding body in mode 10-3-2.

[0096] Figure 50A This is a planar schematic diagram showing the unfolded state of the electrode winding body in mode 10-4-1.

[0097] Figure 50B This is a planar schematic diagram showing the unfolded state of the electrode winding body in mode 10-4-2.

[0098] Figure 51 This is a perspective view showing the appearance of the electrode winding body in method 10-5.

[0099] Figure 52 This is a cross-sectional schematic diagram of the electrode winding body and the center pin in method 10-6.

[0100] Figure 53 This is a cross-sectional schematic diagram of the center pin, representing method 10-7.

[0101] Figure 54A This is a perspective view schematically representing the appearance of the outer packaging can of method 13-2.

[0102] Figure 54B This is a perspective view schematically representing the appearance of the outer packaging can of method 13-3.

[0103] Figure 54C This is a perspective view schematically representing the appearance of the outer packaging can of method 13-4. Detailed Implementation

[0104] Hereinafter, one embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted that the description is presented in the following order.

[0105] A. Secondary battery

[0106] A-1. Structure

[0107] A-2. Actions

[0108] A-3. Manufacturing Method

[0109] B. Application Examples

[0110] B-1. Battery Pack

[0111] B-2. Energy Storage System

[0112] C. Specific Topics

[0113] <A. Secondary Battery>

[0114] First, a secondary battery according to one embodiment of the present disclosure will be described.

[0115] In this embodiment, a cylindrical lithium-ion secondary battery with a cylindrical shape is used as an example for description. However, the secondary battery disclosed herein is not limited to a cylindrical lithium-ion secondary battery, and may be a lithium-ion secondary battery with a shape other than a cylindrical shape, or a secondary battery using electrode reactants other than lithium.

[0116] The charging and discharging principle of a secondary battery is not particularly limited; the following explanation concerns the case where battery capacity is obtained by utilizing the intercalation and deintercalation of electrode reactants. This secondary battery includes a positive electrode, a negative electrode, and an electrolyte. In this secondary battery, to prevent the deposition of electrode reactants on the surface of the negative electrode during charging, the charging capacity of the negative electrode is greater than the discharging capacity of the positive electrode. That is, the electrochemical capacity per unit area of ​​the negative electrode is set to be greater than that of the positive electrode per unit area.

[0117] The types of substances used in the electrode reactions are not specifically limited as described above. Specifically, they are light metals such as alkali metals and alkaline earth metals. Alkali metals include lithium, sodium, and potassium, while alkaline earth metals include beryllium, magnesium, and calcium.

[0118] The following example uses lithium as the electrode reactant. A secondary battery that utilizes the insertion and extraction of lithium to obtain battery capacity is called a lithium-ion secondary battery. In this lithium-ion secondary battery, lithium is inserted and extracted in an ionic state.

[0119] [A-1. Structure]

[0120] (Lithium-ion secondary battery 1)

[0121] Figure 1 The vertical cross-sectional structure along the height direction of the lithium-ion secondary battery 1 (hereinafter simply referred to as secondary battery 1) of this embodiment is shown. Figure 1 The secondary battery 1 shown includes a generally cylindrical outer packaging can 11 and an electrode winding body 20, which serves as a battery element, housed within the outer packaging can 11. Furthermore, the secondary battery 1 includes an outer packaging tube 50 that covers the outer periphery of the outer packaging can 11. It should be noted that, in this specification, the height direction of the secondary battery 1 is defined as the Z-axis direction.

[0122] Specifically, the secondary battery 1, for example, includes inside the outer packaging can 11 a pair of insulating plates 12 and 13, an electrode winding body 20, a positive current collector plate 24 serving as the first electrode current collector plate, and a negative current collector plate 25 serving as the second electrode current collector plate. The electrode winding body 20 is, for example, a structure in which the positive electrode 21 and the negative electrode 22 are stacked and wound together with a separator 23 in between. An electrolyte, which is a liquid electrolyte, is impregnated in the electrode winding body 20. It should be noted that, alternatively, the secondary battery 1 may further include one or more of the following inside the outer packaging can 11: a thermistor element (also called a PTC element) and a reinforcing component.

[0123] (Outer packaging can 11)

[0124] The outer packaging can 11 is a container that houses the positive current collector 24, the negative current collector 25, and the electrode winding 20. The outer packaging can 11 has a bottom 11B and a side wall portion 11W. The bottom 11B is also the negative terminal connected to the negative electrode 22 via the negative current collector 25. The outer packaging can 11 has, for example, a hollow cylindrical structure with its lower end closed in the Z-axis direction and its upper end open. Therefore, the upper end of the outer packaging can 11 is called the open end 11N, and the lower end of the outer packaging can 11 is closed by the generally circular bottom 11B. Between the open end 11N and the bottom 11B is the side wall portion 11W surrounding the electrode winding 20. The side wall portion 11W is erected vertically along the outer edge of the bottom 11B in the height direction, surrounding the electrode winding 20, and includes an open end 11N on the opposite side of the bottom 11B through which the electrode winding 20 can be inserted. The structural material of the outer packaging can 11 includes, for example, a metallic material such as iron. However, a metal material such as nickel may also be plated on the surface of the outer packaging can 11. The insulating plates 12 and 13 are arranged opposite each other, for example, with the electrode winding 20 sandwiched between them in the Z-axis direction. It should be noted that, in this specification, in the Z-axis direction, the open end 11N and its vicinity are sometimes referred to as the upper part of the secondary battery 1, and the closed portion of the outer packaging can 11 and its vicinity are referred to as the lower part of the secondary battery 1.

[0125] (Outer packaging tube 50)

[0126] The outer packaging tube 50 surrounds the outer surface of the side wall 11W of the outer packaging can 11, i.e., the side surface 11WS. However, as... Figure 1 As shown, the outer packaging tube 50 may also cover the bent portion 11P (described later) at the upper end of the outer packaging can 11. Additionally, the outer packaging tube 50 may also cover a portion of the outer surface 11BS of the bottom 11B of the outer packaging can 11. The outer packaging tube 50 is, for example, made of an insulating film containing a polyester resin, a polyamide resin, or a thermoplastic elastomer resin, which has heat-shrinkable properties.

[0127] (Gasket 55)

[0128] A gasket 55 is provided in the gap between the outer packaging tube 50 and the bent portion 11P of the outer packaging can 11. The gasket 55 is an insulating ring component with an opening 55K in the central region of a plane orthogonal to the height direction. A protrusion 14T located in the central region of the battery cover 14 is inserted into the opening 55K. As a structural material for the gasket 55, for example, black modified polyphenylene ether can be used.

[0129] (Insulation boards 12 and 13)

[0130] Each of the insulating plates 12 and 13 has, for example, a surface perpendicular to the central axis CL of the electrode winding body 20, i.e., perpendicular to... Figure 1 The disk-shaped plate is located on the Z-axis plane. In addition, the insulating plates 12 and 13 are arranged to sandwich the electrode winding body 20.

[0131] (Riveted structure 11R)

[0132] On the open end 11N of the outer packaging can 11, for example, a structure is formed in which the battery cover 14 and the safety valve mechanism 30 are riveted together via a gasket 15, namely a riveting structure 11R. With the electrode winding body 20 and the like housed inside the outer packaging can 11, the outer packaging can 11 is sealed by the battery cover 14. The riveting structure 11R has a bent portion 11P, which is called a curled portion. In addition, a reduced diameter portion 11S, which protrudes inward from a part of the outer packaging can 11, is provided between the bent portion 11P and the insulating plate 12.

[0133] (Battery cover 14)

[0134] The battery cover 14 is a sealing component that closes the open end 11N, primarily when the electrode winding body 20 and the like are housed inside the outer packaging can 11. The battery cover 14 is, for example, a conductive body made of the same material as the outer packaging can 11. The battery cover 14 blocks the open end 11N of the outer packaging can 11 and is connected to the positive current collector 24. Therefore, the battery cover 14 is also the positive terminal connected to the positive electrode 21 via the positive current collector 24. The protrusion 14T in the central region of the battery cover 14 protrudes upwards (in the +Z direction), for example. Thus, the area outside the central region of the battery cover 14, i.e., the peripheral region, comes into contact with the safety valve mechanism 30, for example.

[0135] (Washer 15)

[0136] The gasket 15 is a sealing component mainly located between the bent portion 11P of the outer packaging can 11 and the battery cover 14. The gasket 15 seals the gap between the bent portion 11P and the battery cover 14. However, the surface of the gasket 15 may also be coated with, for example, asphalt. The gasket 15 may contain any one or more insulating materials. The type of insulating material is not particularly limited, and may include polymers such as polybutylene terephthalate (PBT) and polypropylene (PP). Among these, polybutylene terephthalate is preferred as the insulating material. This is because, while electrically separating the outer packaging can 11 and the battery cover 14 from each other, the gap between the bent portion 11P and the battery cover 14 is sufficiently sealed.

[0137] (Safety valve mechanism 30)

[0138] The safety valve mechanism 30 releases the internal pressure of the outer packaging can 11 when the internal pressure rises, thereby releasing the sealed state of the outer packaging can 11. The increase in internal pressure of the outer packaging can 11 can be caused by factors such as gases generated during the decomposition reaction of the electrolyte during charging and discharging. Additionally, external heating may also cause the internal pressure of the outer packaging can 11 to rise.

[0139] (Electrode winding body 20)

[0140] An electrode winding 20 is disposed between the positive current collector 24 and the negative current collector 25. The electrode winding 20 has an upper end face 41 facing the positive current collector 24 in the height direction and a lower end face 42 facing the negative current collector 25 in the height direction. The electrode winding 20 is a power generation element that performs charge-discharge reactions and is housed inside the outer packaging can 11. The electrode winding 20 includes a positive electrode 21, a negative electrode 22, a separator 23, and an electrolyte in liquid form.

[0141] Figure 2 This is an unfolded view of the electrode winding body 20, schematically showing a portion of a laminate S20 including a positive electrode 21 as a first electrode, a negative electrode 22 as a second electrode, and a separator 23. In the unfolded laminate S20 of the electrode winding body 20, the positive electrode 21 and the negative electrode 22 are stacked on top of each other with the separator 23 in between. The separator 23 has, for example, two substrates, namely, a first separator component 23A and a second separator component 23B. Therefore, the electrode winding body 20 has a four-layer laminate S20 in which the positive electrode 21, the first separator component 23A, the negative electrode 22, and the second separator component 23B are stacked in sequence. The positive electrode 21, the first separator component 23A, the negative electrode 22, and the second separator component 23B are all generally strip-shaped components with their short sides in the W direction and their long sides in the L direction.

[0142] like Figure 3As shown, in the electrode winding body 20, the laminate S20 is wound around the through hole 26 extending along the central axis CL in a spiral shape on a horizontal cross-section orthogonal to the Z-axis direction. The laminate S20 is wound in an orientation where the W direction is approximately aligned with the Z-axis direction. It should be noted that... Figure 3 An example structure of the electrode winding 20 along a horizontal cross-section orthogonal to the Z-axis direction is shown. However, in Figure 3 For clarity, the description of the diaphragm 23 is omitted. The electrode winding body 20 has a generally cylindrical shape. The positive electrode 21 and the negative electrode 22 are wound while maintaining their opposing positions with the diaphragm 23 in between. A through hole 26, serving as an internal space, is formed at the center of the electrode winding body 20. The through hole 26 is used to insert the assembly core of the electrode winding body 20 and the electrode rod for welding. The through hole 26 extends along the central axis CL in the Z-axis direction and penetrates the electrode winding body 20. Therefore, the laminate S20 is wound around the through hole 26.

[0143] The positive electrode 21, negative electrode 22, and separator 23 are wound such that the separator 23 is disposed on the outermost periphery and the innermost periphery of the electrode winding body 20, respectively. Furthermore, on the outermost periphery of the electrode winding body 20, the negative electrode 22 is disposed outside the positive electrode 21. That is, as... Figure 3 As shown, the outermost positive electrode portion 21out of the positive electrode 21 included in the electrode winding 20 is located further inward than the outermost negative electrode portion 22out of the negative electrode 22 included in the electrode winding 20. Here, the outermost positive electrode portion 21out refers to the outermost circumference of the positive electrode 21 in the electrode winding 20. The outermost negative electrode portion 22out refers to the outermost circumference of the negative electrode 22 in the electrode winding 20. On the other hand, on the innermost circumference of the electrode winding 20, the negative electrode 22 is positioned further inward than the positive electrode 21. That is, as... Figure 3 As shown, the innermost circumferential portion 22in of the negative electrode 22 included in the electrode winding body 20 is located further inward than the innermost circumferential portion 21in of the positive electrode 21 included in the electrode winding body 20. Here, the innermost circumferential portion 21in of the positive electrode refers to the innermost circumference of the positive electrode 21 in the electrode winding body 20. The innermost circumferential portion 22in of the negative electrode refers to the innermost circumference of the negative electrode 22 in the electrode winding body 20. The number of turns of each of the positive electrode 21, negative electrode 22, and diaphragm 23 is not particularly limited and can be arbitrarily set.

[0144] Figure 4A This is a diagram of the positive electrode 21, schematically showing its state before winding. Figure 4B The cross-sectional structure of the positive electrode 21 is shown. Additionally, Figure 4BThe positive electrode 21 is shown along Figure 4A The cross-section shown is in the direction of the arrow on the IVB-IVB line. The positive electrode 21 has a positive current collector 21A, a positive active material layer 21B, and an insulating layer 101. The positive active material layer 21B may be provided on only one side of the positive current collector 21A, or it may be provided on both sides of the positive current collector 21A. Figure 4B The diagram shows the positive electrode active material layer 21B disposed on both sides of the positive electrode current collector 21A. More specifically, the positive electrode current collector 21A includes an inner peripheral surface 21A1 facing the central axis CL, and an outer peripheral surface 21A2 opposite to the inner peripheral surface 21A1. As the positive electrode active material layer 21B, the positive electrode 21 has an inner peripheral active material layer 21B1 covering at least a portion of the inner peripheral surface 21A1, and an outer peripheral active material layer 21B2 covering at least a portion of the outer peripheral surface 21A2. It should be noted that in this specification, the inner peripheral active material layer 21B1 and the outer peripheral active material layer 21B2 are sometimes referred to collectively as the positive electrode active material layer 21B. The positive electrode active material layer 21B extends in two directions: the L direction and the W direction orthogonal to the L direction. The L direction is the winding direction of the laminate S20. The W direction is substantially consistent with the central axis CL.

[0145] The positive current collector 21A includes a positive electrode covered region 211 covered by a positive electrode active material layer 21B and a positive electrode exposed region 212 that is not covered by the positive electrode active material layer 21B and extends in the W direction. The insulating layer 101 extends in the L direction along the first end edge 21BT1 of the positive electrode active material layer 21B located at the boundary K between the positive electrode covered region 211 and the positive electrode exposed region 212. It should be noted that in the positive electrode 21 of this embodiment, as... Figure 4B As shown, the first end edge 21BT1 of the positive electrode active material layer 21B is an inclined surface, and the insulating layer 101 is in contact with the first end edge 21BT1. That is, the insulating layer 101 is formed in such a way that it covers the vicinity of the first end edge 21BT1 of the positive electrode active material layer 21B.

[0146] like Figure 4A As shown, the positive electrode covered region 211 and the positive electrode exposed region 212 extend along the L direction from the winding center side edge 21E1 to the winding outer peripheral side edge 21E2 of the positive electrode 21. That is, in the positive electrode 21, in the winding direction of the electrode winding body 20, from the winding center side edge 21E1 to the winding outer peripheral side edge 21E2 of the positive electrode 21, the positive electrode active material layer 21B is covered by the positive electrode current collector 21A. The positive electrode covered region 211 and the positive electrode exposed region 212 are adjacent to each other in the W direction, which is the short side direction of the positive electrode 21. It should be noted that in Figure 4A as well as Figure 4BThe diagram schematically depicts a positive current collector 21A extending linearly along the W direction. However, in reality, as shown... Figure 1 As shown, the positive electrode edge 212E in the positive electrode exposed area 212 bends towards the central axis CL and connects to the positive electrode current collector 24. That is, the end of the positive electrode exposed area 212 in the W direction forms the upper end face 41 and is connected to the positive electrode current collector 24 (see reference). Figure 1 The upper end face 41 is formed by bending towards the through hole 26 while the positive electrode edge 212E of the positive electrode exposed area 212 is wound up.

[0147] Alternatively, an insulating layer 101 may be provided near the boundary between the positive electrode covered area 211 and the positive electrode exposed area 212. Alternatively, similar to the positive electrode covered area 211 and the positive electrode exposed area 212, the insulating layer 101 may also extend from the winding center edge 21E1 to the winding outer peripheral edge 21E2 of the electrode winding body 20. Alternatively, the insulating layer 101 may be bonded to at least one of the first diaphragm component 23A and the second diaphragm component 23B. This is because it can prevent the positional misalignment of the positive electrode 21 and the diaphragm 23. Alternatively, the insulating layer 101 may contain a resin containing polyvinylidene fluoride (PVDF). This is because by containing PVDF, for example, the insulating layer 101 can be swollen by a solvent contained in the electrolyte, allowing it to bond well to the diaphragm 23.

[0148] Figure 5A This is a diagram of the unfolded state of negative electrode 22, schematically showing its state before winding. Figure 5B The cross-sectional structure of the negative electrode 22 is shown. It should be noted that... Figure 5B It shows along Figure 5A The cross-section shown is in the direction of the arrow on the VB-VB line. The negative electrode 22 includes, for example, a negative electrode current collector 22A as a second electrode current collector and a negative electrode active material layer 22B covering a portion of the negative electrode current collector 22A. The negative electrode active material layer 22B may be provided on only one side of the negative electrode current collector 22A, or it may be provided on both sides of the negative electrode current collector 22A. Figure 5BThe diagram shows the negative electrode active material layer 22B disposed on both sides of the negative electrode current collector 22A. More specifically, the negative electrode current collector 22A includes: an inner peripheral surface 22A1 facing the winding center side of the electrode winding body 20, i.e., the central axis CL; and an outer peripheral surface 22A2 facing the opposite side of the winding center side of the electrode winding body 20, i.e., the opposite side of the inner peripheral surface 22A1. As the negative electrode active material layer 22B, the negative electrode 22 has an inner peripheral active material layer 22B1 covering at least a portion of the inner peripheral surface 22A1 and an outer peripheral active material layer 22B2 covering at least a portion of the outer peripheral surface 22A2. It should be noted that in this specification, the inner peripheral active material layer 22B1 and the outer peripheral active material layer 22B2 are sometimes referred to collectively as the negative electrode active material layer 22B.

[0149] The negative electrode 22 has: a negative electrode covered region 221, in which the negative electrode current collector 22A is covered by a negative electrode active material layer 22B; and a negative electrode exposed region 222, in which the negative electrode current collector 22A is exposed and not covered by the negative electrode active material layer 22B. Figure 5A As shown, the negative electrode covered area 221 and the negative electrode exposed area 222 extend along the L direction, which is the long side of the negative electrode 22. The negative electrode exposed area 222 extends from the central axial end edge 22E1 to the outer peripheral end edge 22E2 of the negative electrode 22 in the winding direction of the electrode winding body 20. In contrast, the negative electrode covered area 221 is not provided at the central axial end edge 22E1 and the outer peripheral end edge 22E2 of the negative electrode 22. Figure 5A As shown, a portion of the negative electrode exposed region 222 is formed such that it sandwiches the negative electrode covering region 221 in the L direction, which is the long side direction of the negative electrode 22. Specifically, the negative electrode exposed region 222 includes a first portion 222A, a second portion 222B, and a third portion 222C. In addition, the negative electrode 22 further has a lower end edge 22E3 extending in the L direction on the lower side of the electrode winding body 20. The first portion 222A is arranged adjacent to the negative electrode covering region 221 in the W direction and extends from the central axis end edge 22E1 to the outer peripheral end edge 22E2 in the L direction. That is, the first portion 222A is the region extending from the negative electrode active material layer 22B in the W direction. The second portion 222B and the third portion 222C are arranged such that they sandwich the negative electrode covering region 221 in the L direction. The first portion 222A is located near the lower end edge 22E3 of the negative electrode 22. The second part 222B is located, for example, near the central axial end edge 22E1 of the negative electrode 22, and the third part 222C is located near the outer peripheral end edge 22E2 of the negative electrode 22. It should be noted that... Figure 5A as well as Figure 5BThe diagram schematically depicts a negative current collector 22A extending linearly along the W direction. However, in reality, as shown... Figure 1 As shown, the negative electrode edge 222E in the negative electrode exposed area 222 is bent towards the central axis CL and connected to the negative electrode current collector 25. That is, the end of the negative electrode exposed area 222 in the W direction forms the lower end face 42 and is connected to the negative electrode current collector 25 (see reference). Figure 1 The lower end face 42 is formed by bending towards the through hole 26 while the negative electrode edge 222E of the negative electrode exposed area 222 is wound.

[0150] In the stacked body S20 of the electrode winding body 20, the positive electrode 21 and the negative electrode 22 are stacked with the separator 23 in such a way that the first portions 222A of the positive electrode exposed region 212 and the negative electrode exposed region 222 are opposite to each other along the W direction, which is the width direction. The electrode winding body 20 fixes the end of the separator 23 by attaching the fixing strap 46 to its side portion 45 so that it does not loosen.

[0151] In secondary battery 1, such as Figure 2 As shown, when the width of the positive electrode exposed region 212 is A and the width of the first portion 222A of the negative electrode exposed region 222 is B, it is preferable that A > B. For example, when the width A = 7 (mm), the width B = 4 (mm). Furthermore, when the width of the portion protruding from the outer edge of the diaphragm 23 in the width direction of the positive electrode exposed region 212 is C and the width of the portion protruding from the outer edge of the diaphragm 23 on the opposite side in the width direction of the diaphragm 23 in the first portion 222A of the negative electrode exposed region 222 is D, it is preferable that C > D. For example, when the width C = 4.5 (mm), the width D = 3 (mm).

[0152] like Figure 1As shown, in the upper part of the secondary battery 1, multiple adjacent portions of the positive electrode edge 212E of the positive electrode exposed region 212 wound around the central axis CL are bent towards the central axis CL in a radially (R direction) manner, forming the upper end face 41 of the electrode winding body 20. Similarly, in the lower part of the secondary battery 1, multiple adjacent portions of the negative electrode edge 222E of the negative electrode exposed region 222 wound around the central axis CL are bent towards the central axis CL in a radially (R direction) manner, forming the lower end face 42 of the electrode winding body 20. Therefore, multiple portions of the positive electrode edge 212E of the positive electrode exposed region 212 are concentrated on the upper end face 41 of the electrode winding body 20, and multiple portions of the negative electrode edge 222E of the negative electrode exposed region 222 are concentrated on the lower end face 42 of the electrode winding body 20. To ensure good contact between the positive current collector 24 and the positive electrode edge 212E, multiple portions of the positive electrode edge 212E, which bends towards the central axis CL, are flat surfaces. Similarly, to ensure good contact between the negative current collector 25 and the negative electrode edge 222E, multiple portions of the negative electrode edge 222E, which bends towards the central axis CL, are flat surfaces. It should be noted that the flat surfaces referred to here include not only completely flat surfaces, but also surfaces with some unevenness and surface roughness, to the extent that the exposed positive electrode region 212 and the exposed negative electrode region 222 can respectively engage with the positive current collector 24 and the negative current collector 25.

[0153] As described later, the positive current collector 21A is made of aluminum foil, for example. On the other hand, as described later, the negative current collector 22A is made of copper foil, for example. In this case, the positive current collector 21A is softer than the negative current collector 22A. That is, the Young's modulus of the positive electrode exposed region 212 is lower than that of the negative electrode exposed region 222. Therefore, in one embodiment, it is more preferable that the widths A to D have a relationship of A > B and C > D. In this case, when the positive electrode exposed region 212 and the negative electrode exposed region 222 are bent simultaneously from both electrode sides with the same pressure, the height measured from the front end of the diaphragm 23 of the bent portion becomes the same in both the positive electrode 21 and the negative electrode 22. At this time, the positive electrode edge 212E ( Figure 1 The multiple parts of the electrode are bent and appropriately overlapped. Therefore, the positive electrode exposed area 212 can be easily joined to the positive electrode current collector 24. Similarly, the negative electrode edge 222E ( Figure 1 The multiple parts of the electrode are bent and appropriately overlapped. Therefore, the negative electrode exposed area 222 and the negative electrode current collector 25 can be easily joined. The joining method mentioned here refers to joining by means of laser welding, for example, but the joining method is not limited to laser welding.

[0154] like Figure 2As shown, in the positive electrode exposed region 212 of the positive electrode 21, the portion facing the negative electrode 22 across the separator 23 is covered by the insulating layer 101. The insulating layer 101 has a width of, for example, 3 mm in the W direction. The insulating layer 101 covers the entire area of ​​the positive electrode exposed region 212 of the positive electrode 21, which faces the negative electrode covered region 221 of the negative electrode 22 across the separator 23. For example, when a foreign object enters between the negative electrode covered region 221 and the positive electrode exposed region 212, the insulating layer 101 can effectively prevent an internal short circuit in the secondary battery 1. In addition, when an impact is applied to the secondary battery 1, the insulating layer 101 absorbs the impact, effectively preventing bending of the positive electrode exposed region 212 and short circuit between the positive electrode exposed region 212 and the negative electrode 22.

[0155] (Insulating tapes 53 and 54)

[0156] Alternatively, the secondary battery 1 may have insulating strips 53 and 54 further provided in the gap between the outer packaging can 11 and the electrode winding body 20. The positive electrode exposed area 212 and the negative electrode exposed area 222, concentrated on the upper end face 41 and the lower end face 42, are exposed conductive materials such as bare metal foil. Therefore, when the positive electrode exposed area 212 and the negative electrode exposed area 222 are close to the outer packaging can 11, a short circuit between the positive electrode 21 and the negative electrode 22 may occur through the outer packaging can 11. In addition, a short circuit may also occur when the positive electrode current collector 24 located on the upper end face 41 is close to the outer packaging can 11. Therefore, insulating strips 53 and 54 can be provided as insulating components. The insulating strips 53 and 54 are, for example, adhesive strips made of any one of polypropylene, polyethylene terephthalate, and polyimide as the material of the substrate layer, and have an adhesive layer on one side of the substrate layer. In order to prevent the volume of the electrode winding body 20 from being reduced due to the installation of insulating tapes 53 and 54, the insulating tapes 53 and 54 are configured not to overlap with the fixing tape 46 that is pasted to the side portion 45, and the thickness of the insulating tapes 53 and 54 is set to be less than or equal to the thickness of the fixing tape 46.

[0157] (Positive current collector 24 and negative current collector 25)

[0158] In typical lithium-ion secondary batteries, for example, a current extraction lead is welded to both the positive and negative electrodes. However, in this case, the internal resistance of the lithium-ion secondary battery is high, and it heats up during discharge, becoming very hot, thus unsuitable for high-rate discharge. Therefore, in the secondary battery 1 of this embodiment, the positive electrode current collector 24 is arranged opposite to the upper end face 41, and the negative electrode current collector 25 is arranged opposite to the lower end face 42. Multiple points are welded between the positive electrode covering area 211 and the positive electrode current collector 24 on the upper end face 41, and multiple points are welded between the negative electrode covering area 221 and the negative electrode current collector 25 on the lower end face 42. This reduces the internal resistance of the secondary battery 1. The fact that the upper end face 41 and the lower end face 42 are flat, as described above, also contributes to low resistance. The positive electrode current collector 24 is disposed between the battery cover 14 and the upper end face 41. The positive current collector 24 is electrically connected to the battery cover 14, for example, via a safety valve mechanism 30. The negative current collector 25 is disposed between the bottom 11B and the lower end face 42 of the outer packaging can 11. The negative current collector 25 is electrically connected, for example, to the inner surface of the bottom 11B of the outer packaging can 11. Figure 6A This is an unfolded diagram showing a structural example of the positive current collector 24. Figure 6B This is an unfolded view showing a structural example of the negative current collector 25. The positive current collector 24 is, for example, a metal plate made of aluminum or aluminum alloy monomers, or composite materials thereof. The negative current collector 25 is, for example, a metal plate made of nickel, nickel alloy, copper, or copper alloy monomers, or composite materials thereof.

[0159] like Figure 6A As shown, the positive current collector 24 has a generally fan-shaped portion 31 and a generally rectangular strip-shaped portion 32. However, the shape of the positive current collector 24 is not limited to... Figure 6A The shape shown can be chosen arbitrarily. It should be noted that in secondary battery 1, as... Figure 1 As shown, the positive current collector 24 is housed in the outer packaging can 11 with the strip portion 32 bent relative to the fan portion 31. Figure 6A The positive current collector 24 in its deployed state is shown. The fan-shaped portion 31 is a opposed portion connected to the upper end face 41. The fan-shaped portion 31, for example, has an outer edge including a straight portion and a curved portion. An opening 35 is formed near the center of the fan-shaped portion 31. Figure 6A The example illustrates a case where the opening 35 has a circular planar shape on a horizontal plane orthogonal to the Z-axis direction. The strip-shaped portion 32 is connected, for example, to a straight portion of the outer edge of the fan-shaped portion 31. The strip-shaped portion 32 extends in a direction intersecting the straight portion 31S of the fan-shaped portion 31. Figure 1As shown, in the secondary battery 1, the positive electrode current collector 24 is arranged such that the opening 35 and the through hole 26 coincide in the Z-axis direction. That is, the opening 35 is located at a position that coincides with a portion of the winding center side of the upper end face 41 in the Z-axis direction. Here, the diameter D35 of the opening 35 can be smaller than the diameter D26 of the through hole 26.

[0160] Figure 6A The section indicated by the diagonal line is the insulating portion 32A within the strip-shaped portion 32. The insulating portion 32A is a part of the strip-shaped portion 32, and is the portion to which insulating tape is adhered or coated with insulating material. In the strip-shaped portion 32, the lower part of the insulating portion 32A is the connecting portion 32B, which connects to the sealing plate that also serves as an external terminal. The sealing plate is electrically connected to the battery cover 14. It should be noted that, as... Figure 1 As shown, in the case where the secondary battery 1 has a battery structure without a metal center pin in the through hole 26, the possibility of the strip portion 32 contacting the negative electrode potential is low. Therefore, the positive electrode current collector 24 may not have an insulating portion 32A. When the positive electrode current collector 24 does not have an insulating portion 32A, the charge / discharge capacity can be increased by increasing the width of the positive electrode 21 and the negative electrode 22 by an amount equivalent to the thickness of the insulating portion 32A.

[0161] Figure 6B The shape of the negative current collector 25 shown is similar to Figure 6A The positive current collector 24 shown has almost the same shape. The negative current collector 25 has a generally fan-shaped portion 33 and a generally rectangular strip-shaped portion 34. However, the shape of the negative current collector 25 is not limited to... Figure 6B The shape shown can be chosen arbitrarily. It should be noted that in secondary battery 1, as... Figure 1 As shown, the negative electrode current collector 25 is housed in the outer packaging can 11 with the strip portion 34 bent relative to the fan portion 33. Figure 6BThe negative current collector plate 25 in its unfolded state is shown. The fan-shaped portion 33 is a opposed portion connected to the lower end face 42. The fan-shaped portion 33 has, for example, an outer edge including a straight portion and a curved portion. The strip-shaped portion 34 is connected, for example, to the straight portion 33S in the outer edge of the fan-shaped portion 33. The strip-shaped portion 34 extends in a direction intersecting the straight portion of the fan-shaped portion 33. The strip-shaped portion 34 of the negative current collector plate 25 is shorter than the strip-shaped portion 32 of the positive current collector plate 24 and does not have a portion corresponding to the insulating portion 32A of the positive current collector plate 24. A plurality of circular protrusions 37, as indicated by circular markings, are provided on the strip-shaped portion 34. At least a portion of the plurality of protrusions 37 is welded to the bottom 11B of the outer packaging can 11. During resistance welding, the current is concentrated on the protrusions 37, the protrusions 37 melt, and the strip-shaped portion 34 is welded to the bottom 11B of the outer packaging can 11. Similar to the positive electrode current collector 24, an opening 36 is formed near the center of the fan-shaped portion 33 on the negative electrode current collector 25. In the secondary battery 1, the negative electrode current collector 25 is arranged such that the opening 36 and the through hole 26 coincide in the Z-axis direction. Figure 6B The example illustrates the case where the opening 36 has a circular planar shape on a horizontal plane orthogonal to the Z-axis direction.

[0162] The fan-shaped portion 31 of the positive electrode current collector 24, due to its planar shape, only covers a portion of the upper end face 41. Similarly, the fan-shaped portion 33 of the negative electrode current collector 25, due to its planar shape, only covers a portion of the lower end face 42. There are two reasons why the fan-shaped portions 31 and 33 do not completely cover the upper end face 41 and the lower end face 42, for example. The first reason is, for example, to ensure that the electrolyte can smoothly penetrate into the electrode winding body 20 during the assembly of the secondary battery 1. Especially in the secondary battery 1 of this embodiment, the positive electrode current collector 24 is positioned such that the opening 35 coincides with a portion of the winding center side of the upper end face 41 in the Z-axis direction. Therefore, a portion of the positive electrode edge 212E constituting the upper end face 41 is exposed in the opening 35, not covered by the fan-shaped portion 31 of the positive electrode current collector 24. Therefore, the secondary battery 1 has a structure in which the electrolyte penetrates into the electrode winding body 20 more rapidly. The second reason is to facilitate the release of gases generated when lithium-ion secondary batteries are in an abnormally high temperature or overcharged state.

[0163] (Positive current collector 21A)

[0164] The positive current collector 21A may contain conductive materials such as aluminum. The positive current collector 21A may be a metal foil made of aluminum or an aluminum alloy.

[0165] (Positive electrode active material layer 21B)

[0166] The positive electrode active material layer 21B comprises one or more positive electrode materials capable of lithium intercalation and deintercalation as positive electrode active materials. Furthermore, the positive electrode active material layer 21B may further comprise one or more other materials such as a positive electrode binder and a positive electrode conductive agent. The positive electrode material is preferably a lithium-containing compound, and more specifically, preferably a lithium-containing composite oxide and a lithium-containing phosphate compound. The lithium-containing composite oxide is an oxide containing lithium and one or more other elements, i.e., elements other than lithium, as constituent elements. The lithium-containing composite oxide has, for example, any one of layered rock salt type and spinel type crystal structures. The lithium-containing phosphate compound is a phosphate compound containing lithium and one or more other elements as constituent elements, for example, having a olivine type crystal structure. In particular, the positive electrode active material layer 21B may contain at least one of lithium cobalt oxide, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide as positive electrode active materials. The positive electrode binder comprises, for example, any one or more of synthetic rubber and polymer compounds. Synthetic rubbers include, for example, styrene-butadiene rubber, fluorinated rubber, and ethylene propylene diene monomer (EPDM) rubber. Polymer compounds include, for example, polyvinylidene fluoride (PVDF) and polyimide. Positive electrode conductive agents include, for example, any one or more carbon materials. These carbon materials include, for example, graphite, carbon black, acetylene black, and Ketjen black. Furthermore, the positive electrode conductive agent can be any conductive material, including metals and conductive polymers.

[0167] (Negative current collector 22A)

[0168] The negative current collector 22A comprises, for example, a conductive material such as copper. The negative current collector 22A is, for example, a metal foil made of nickel, a nickel alloy, copper, or a copper alloy. The surface of the negative current collector 22A is preferably roughened. This is because, through the so-called anchoring effect, the adhesion between the negative active material layer 22B and the negative current collector 22A is improved. In this case, at least in the region opposite to the negative active material layer 22B, the surface of the negative current collector 22A can be roughened. Roughening methods include, for example, methods that form microparticles using electrolytic processing. In electrolytic processing, since microparticles are formed on the surface of the negative current collector 22A by electrolysis in an electrolytic cell, unevenness is provided on the surface of the negative current collector 22A. Copper foil produced by electrolysis is generally called electrolytic copper foil.

[0169] (Negative electrode active material layer 22B)

[0170] The negative electrode active material layer 22B comprises one or more negative electrode materials capable of lithium insertion and extraction as negative electrode active materials. Furthermore, the negative electrode active material layer 22B may further comprise one or more other materials such as a negative electrode binder and a negative electrode conductive agent. The negative electrode material is, for example, a carbon material. This is because the change in crystal structure during lithium insertion and extraction is very small, thus a high energy density can be stably obtained. In addition, since the carbon material also functions as a negative electrode conductive agent, the conductivity of the negative electrode active material layer 22B is improved. The carbon material is, for example, easily graphitized carbon, difficult-to-graphitized carbon, and graphite. Furthermore, the interplanar spacing of the (002) facets in difficult-to-graphitized carbon is preferably 0.37 nm or more. The interplanar spacing of the (002) facets in graphite is preferably 0.34 nm or less. More specifically, the carbon material is, for example, pyrolytic carbon, coke, glassy carbon fibers, sintered organic polymer compounds, activated carbon, and carbon black. This type of coke includes pitch coke, needle coke, and petroleum coke. The sintered organic polymer compound is produced by sintering (carbonizing) polymer compounds such as phenolic resin and furan resin at an appropriate temperature. Furthermore, the carbon material can be low-crystallinity carbon after heat treatment at a temperature below approximately 1000°C, or it can be amorphous carbon. It should be noted that the shape of the carbon material can be any of fibrous, spherical, granular, or flake-like. In secondary battery 1, if the open-circuit voltage during full charging, i.e., the battery voltage, is 4.25V or higher, then compared to the case where the open-circuit voltage during full charging is 4.20V, even using the same positive electrode active material, the lithium extraction / intercalation per unit mass increases. Therefore, the amounts of the positive and negative electrode active materials are adjusted accordingly. This results in a high energy density.

[0171] Furthermore, the negative electrode active material layer 22B may contain a silicon-containing material as the negative electrode active material, comprising at least one of silicon, silicon oxide, silicon carbide compound, and silicon alloy. Silicon-containing material refers to any material containing silicon as a constituent element. Alternatively, the silicon-containing material may contain only silicon as a constituent element. It should be noted that the type of silicon-containing material may be only one type or two or more types. The silicon-containing material can form an alloy with lithium and may be elemental silicon, a silicon alloy, a silicon compound, a mixture of two or more of these, or a material containing one or more of these phases. Furthermore, the silicon-containing material may be crystalline, amorphous, or contain both crystalline and amorphous portions. However, the term "elemental" here refers only to a general elemental substance, and therefore may contain trace amounts of impurities. That is, the purity of the elemental substance is not necessarily limited to 100%. Silicon alloys may, for example, contain any one or two or more of tin, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony, and chromium as constituent elements other than silicon. Silicon compounds may contain one or more of carbon and oxygen as constituent elements other than silicon. It should be noted that silicon compounds, for example, as constituent elements other than silicon, may also contain one or more of the constituent elements described in the section on silicon alloys. Specifically, silicon alloys and silicon compounds include, for example, SiB4, SiB6, Mg2Si, Ni2Si, TiSi2, MoSi2, CoSi2, NiSi2, CaSi2, CrSi2, Cu5Si, FeSi2, MnSi2, NbSi2, TaSi2, VSi2, WSi2, ZnSi2, SiC, Si3N4, Si2N2O, and SiO. v (0 < v ≤ 2), etc. In addition, the range of v can be set arbitrarily, for example, it can be 0.2 < v < 1.4.

[0172] (Diaphragm 23)

[0173] A separator 23 is located between the positive electrode 21 and the negative electrode 22. The separator 23 allows lithium ions to pass through while preventing short circuits caused by the contact between the positive and negative electrodes 21 and 22. The separator 23 can be any one or more porous membranes such as synthetic resins and ceramics, or it can be a laminate of two or more porous membranes. Synthetic resins include, for example, polytetrafluoroethylene, polypropylene, and polyethylene. However, the separator 23 may also have a substrate made of a single-layer polyolefin porous membrane containing polyethylene. This is because, compared to laminated membranes, it can achieve better high output characteristics. When both the first separator component 23A and the second separator component constituting the separator 23 are single-layer porous membranes made of polyolefin, the thickness of the porous membrane can be, for example, 10 μm or more and 15 μm or less. By having a thickness of 10 μm or more for the single-layer porous membrane made of polyolefin, internal short circuits can be sufficiently avoided. If the thickness of the single-layer porous membrane made of polyolefin is 15 μm or less, even better discharge capacity characteristics can be obtained. In addition, the areal density of this porous membrane can be, for example, 6.3 g / m³. 2 Above and 8.3g / m 2 Below. If the areal density of a single-layer porous membrane made of polyolefin is 6.3 g / m³. 2 The above can effectively prevent internal short circuits. If the areal density of a single-layer porous membrane made of polyolefin is 8.3 g / m³... 2 The following approach can yield better discharge capacity characteristics.

[0174] In particular, the separator 23 may include, for example, a porous membrane as the substrate described above, and a polymer compound layer disposed on one or both sides of the substrate layer. This is because, due to the improved adhesion between the separator 23 and the positive electrode 21 and the negative electrode 22, deformation of the electrode winding 20 can be suppressed. Consequently, the decomposition reaction of the electrolyte is suppressed, and leakage of the electrolyte impregnated into the substrate is also suppressed. Therefore, even with repeated charging and discharging, the resistance is unlikely to rise, and battery swelling is suppressed. The polymer compound layer may, for example, contain a polymer compound such as polyvinylidene fluoride. This is because it has excellent physical strength and is electrochemically stable. Alternatively, the polymer compound may be a compound other than polyvinylidene fluoride. When forming this polymer compound layer, for example, a solution of the polymer compound dissolved in an organic solvent is coated onto the substrate, and then the substrate is dried. It should be noted that the substrate may also be dried after being impregnated in the solution. The polymer compound layer may, for example, contain any one or more of insulating particles such as inorganic particles. Inorganic particles include, for example, aluminum oxide and aluminum nitride.

[0175] (Electrolyte)

[0176] The electrolyte comprises a solvent and an electrolyte salt. However, the electrolyte may further comprise one or more other materials, such as additives. The solvent comprises one or more non-aqueous solvents, such as organic solvents. An electrolyte comprising a non-aqueous solvent is called a non-aqueous electrolyte. The non-aqueous solvent may, for example, contain fluorinated compounds and dinitrile compounds. The fluorinated compound may, for example, comprise at least one of fluorinated ethylene carbonate, trifluorocarbonate, methyl ethyl trifluorocarbonate, fluorinated carboxylic acid esters, and fluoroethers. In addition, the non-aqueous solvent may further comprise nitrile compounds other than dinitrile compounds, such as at least one of mononitrile compounds and trinitrile compounds. As a dinitrile compound, succinate (SN) is preferred, for example. However, the dinitrile compound is not limited to succinate; for example, it may also be other dinitrile compounds such as adiponitrile.

[0177] The electrolyte salt may include one or more of the following: lithium salts. Alternatively, the electrolyte salt may include salts other than lithium salts. These other salts may be salts of light metals other than lithium. Examples of lithium salts 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). Lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, and lithium hexafluoroarsenate are preferred, and lithium hexafluorophosphate is more preferred. The content of the electrolyte salt is not particularly limited, but it is preferably 0.3 mol / kg to 3 mol / kg relative to the solvent. When the electrolyte contains LiPF6 as the electrolyte salt, the concentration of LiPF6 in the electrolyte can be 1.25 mol / kg or more and 1.45 mol / kg or less. This is because it can prevent cycle degradation caused by salt consumption (decomposition) during high-load charging, thus improving high-load cycling characteristics. Alternatively, when LiBF4 is further included as the electrolyte salt in addition to LiPF6, the concentration of LiBF4 in the electrolyte is 0.001% (wt%) or more and 0.1% (wt%) or less. This is because it can more effectively prevent cycle degradation caused by salt consumption (decomposition) during high-load charging, thus further improving high-load cycling characteristics.

[0178] [1-2. Actions]

[0179] In the secondary battery 1 of this embodiment, for example, during charging, lithium ions are deintercalated from the positive electrode 21 and intercalated into the negative electrode 22 via the electrolyte. Additionally, in the secondary battery 1, for example, during discharging, lithium ions are deintercalated from the negative electrode 22 and intercalated into the positive electrode 21 via the electrolyte.

[0180] [1-3. Manufacturing Method]

[0181] Apart from Figures 1-6B In addition, refer to Figure 7 The manufacturing method of secondary battery 1 will be explained. Figure 7 This is an explanation Figure 1 The diagram shows a three-dimensional representation of the manufacturing process of a secondary battery.

[0182] First, a positive current collector 21A is prepared, and a positive active material layer 21B is selectively formed on the surface of the positive current collector 21A. Then, an insulating layer 101 is formed on the surface of the positive current collector 21A along the first end edge 21BT1 of the positive active material layer 21B. Furthermore, for example, a thin-walled portion 61 is formed by laser ablation of a predetermined area of ​​the positive active material layer 21B. Through these operations, a positive electrode 21 is obtained. Next, a negative current collector 22A is prepared, and a negative active material layer 22B is selectively formed on the surface of the negative current collector 22A, thereby forming a negative electrode 22 having a negative electrode covered region 221 and a negative electrode exposed region 222. The positive electrode 21 and the negative electrode 22 can be dried. Next, the positive electrode 21 and the negative electrode 22 are overlapped with the first portion 222A of the positive electrode exposed area 212 and the negative electrode exposed area 222 facing opposite sides in the W direction, thereby creating a laminate S20. Then, the laminate S20 is wound into a spiral shape to form a through hole 26. At this time, for example, a cylindrical core is used as a clamp, and the laminate S20 is wound around the cylindrical core. Furthermore, after attaching the fixing tape 46 to the outermost periphery of the spirally wound laminate S20, the core is removed. Thus, as Figure 7 The electrode winding body 20 is obtained as shown in (A).

[0183] Next, as Figure 7 As shown in (B), for example, by pressing the end of a plate or the like with a thickness of 0.5 mm perpendicularly, i.e., along the Z-axis, to the upper end face 41 and the lower end face 42 of the electrode winding body 20, a portion of the upper end face 41 and a portion of the lower end face 42 are partially bent. As a result, a groove 43 is created that extends radially (in the R direction) from the through hole 26. It should be noted that... Figure 7 The number and configuration of slots 43 shown in B are examples, and this disclosure is not limited thereto.

[0184] Next, as Figure 7 As shown in (C), substantially the same pressure is applied substantially simultaneously to the upper end face 41 and the lower end face 42 in a substantially vertical direction from above and below the electrode winding body 20. At this time, a rod-shaped clamp is inserted into the through hole 26. As a result, the first portion 222A of the positive electrode exposed region 212 and the negative electrode exposed region 222 are bent respectively, so that the upper end face 41 and the lower end face 42 become flat surfaces respectively. At this time, it is also possible that multiple portions of the positive electrode edge 212E of the positive electrode exposed region 212 on the upper end face 41, which are adjacent in the radial direction of the electrode winding body 20, are bent toward the through hole 26 in a manner that overlaps with each other. Similarly, it is also possible that multiple portions of the negative electrode edge 222E of the negative electrode exposed region 222 on the lower end face 42, which are adjacent in the radial direction of the electrode winding body 20, are bent toward the through hole 26 in a manner that overlaps with each other. Then, the fan-shaped portion 31 of the positive electrode current collector 24 is joined to the upper end face 41 by laser welding or the like, and the fan-shaped portion 33 of the negative electrode current collector 25 is joined to the lower end face 42 by laser welding or the like.

[0185] Next, insulating tapes 53 and 54 are attached to the designated positions on the electrode winding body 20. Then, as... Figure 7 As shown in (D), the strip portion 32 of the positive current collector plate 24 is bent so that the strip portion 32 is inserted through the hole 12H of the insulating plate 12. In addition, the strip portion 34 of the negative current collector plate 25 is bent so that the strip portion 34 is inserted through the hole 13H of the insulating plate 13.

[0186] Next, the electrode winding body 20, assembled as described above, is inserted into... Figure 7 Inside the outer packaging can 11 shown in (E), the bottom 11B of the outer packaging can 11 is then welded to the negative electrode current collector 25. Then, a reduced diameter portion 11S is formed near the open end 11N of the outer packaging can 11. Furthermore, after the electrolyte is injected into the outer packaging can 11, the strip portion 32 of the positive electrode current collector 24 and the safety valve mechanism 30 are welded.

[0187] Next, as Figure 7 As shown in (F), the outer packaging can 11 is sealed using the reduced diameter section 11S, gasket 15, safety valve mechanism 30, and battery cover 14. Finally, the outer packaging tube 50 is placed over the outer packaging can 11 on the battery cover 14, on which the gasket 55 is installed. Then, hot air is blown onto the outer packaging tube 50 to heat it and cause it to shrink, so that the outer packaging tube 50 is sealed to the outer surface of the outer packaging can 11.

[0188] Thus, the secondary battery 1 of this embodiment is completed.

[0189] <B. Application Examples>

[0190] The use of the secondary battery 1, as one embodiment of the present disclosure described above, is as follows.

[0191] [B-1. Battery Pack]

[0192] Figure 8 This is a block diagram illustrating an example of a circuit structure when a battery (hereinafter appropriately referred to as a secondary battery) according to an embodiment of the present invention is applied to a battery pack 300. The battery pack 300 includes: a battery pack 301; an outer casing 305; a switching unit 304 having a charging control switch 302a and a discharging control switch 303a; a current sensing resistor 307; a temperature sensing element 308; and a control unit 310.

[0193] The battery pack 300 has a positive terminal 321 and a negative terminal 322. During charging, the positive terminal 321 and the negative terminal 322 are connected to the positive and negative terminals of the charger, respectively, for charging. In addition, when using electronic devices, the positive terminal 321 and the negative terminal 322 are connected to the positive and negative terminals of the electronic devices, respectively, for discharging.

[0194] The battery pack 301 is formed by connecting multiple secondary batteries 301a in series or parallel. The secondary battery 1 described above can be used as a secondary battery 301a. It should be noted that... Figure 8 The example shown is six secondary batteries 301a connected in a 2-parallel, 3-series (2P3S) configuration. However, in addition to this, there are also any other connection methods, such as n-parallel, m-series (where n and m are integers).

[0195] The switching unit 304 includes a charging control switch 302a and a diode 302b, and a discharging control switch 303a and a diode 303b, controlled by the control unit 310. Diode 302b has a polarity that is reversed relative to the charging current flowing from the positive terminal 321 to the battery pack 301, and forward relative to the discharging current flowing from the negative terminal 322 to the battery pack 301. Diode 303b has a polarity that is forward relative to the charging current and reverse relative to the discharging current. It should be noted that... Figure 8 In the middle, the switch part 304 is provided on the + side, but it can also be provided on the - side.

[0196] The charging control switch 302a is controlled by the charging / discharging control unit to be turned off when the battery voltage reaches the overcharge detection voltage, thus preventing charging current from flowing in the current path of the battery pack 301. After the charging control switch 302a is turned off, discharge can only occur via diode 302b. Furthermore, it is controlled by the control unit 310 to be turned off when a large current flows during charging, thereby blocking the charging current flowing through the current path of the battery pack 301. Similarly, the discharging control switch 303a is controlled by the control unit 310 to be turned off when the battery voltage reaches the over-discharge detection voltage, thus preventing discharging current from flowing in the current path of the battery pack 301. After the discharging control switch 303a is turned off, charging can only occur via diode 303b. Furthermore, it is controlled by the control unit 310 to be turned off when a large current flows during discharging, thereby blocking the discharging current flowing through the current path of the battery pack 301.

[0197] A temperature sensing element 308, such as a thermistor, is positioned near the battery pack 301 to measure the temperature of the battery pack 301 and supply the measured temperature data to the control unit 310. A voltage sensing unit 311 measures the voltage of the battery pack 301 and each of its constituent secondary batteries 301a, performs an analog-to-digital conversion on the measured voltage data, and supplies it to the control unit 310. A current sensing unit 313 uses a current sensing resistor 307 to measure the current and supplies the measured current data to the control unit 310. A switch control unit 314 controls the charging control switch 302a and the discharging control switch 303a of the switch unit 304 based on the voltage and current data input from the voltage sensing unit 311 and the current sensing unit 313.

[0198] When the voltage of any one of the multiple secondary batteries 301a falls below the overcharge detection voltage or the over-discharge detection voltage, or when a large current flows rapidly, the switch control unit 314 sends a control signal to the switch unit 304 to prevent overcharging, over-discharging, and overcurrent charging / discharging. Here, for example, in the case of a lithium-ion secondary battery, the overcharge detection voltage is set to, for example, 4.20V ± 0.05V, and the over-discharge detection voltage is set to, for example, 2.4V ± 0.1V.

[0199] The charge / discharge control switch can be a semiconductor switch such as a MOSFET. In this case, the parasitic diodes of the MOSFET function as diodes 302b and 303b. When using a P-channel FET as the charge / discharge control switch, the switch control unit 314 supplies control signals DO and CO to the gates of each of the charge control switch 302a and the discharge control switch 303a, respectively. When the charge control switch 302a and the discharge control switch 303a are P-channel type, they are set to ON by a gate potential that is at least a predetermined value lower than the source potential. That is, during normal charging and discharging operations, the control signals CO and DO are set to low level, thus setting the charge control switch 302a and the discharge control switch 303a to the ON state.

[0200] For example, during overcharging or over-discharging, control signals CO and DO are set to high level, and charging control switch 302a and discharging control switch 303a are set to OFF state.

[0201] The memory 317 is composed of RAM and ROM, such as an EPROM (Erasable Programmable Read Only Memory), which is a non-volatile memory. The memory 317 stores values ​​calculated by the control unit 310, the internal resistance values ​​of each secondary battery 301a in its initial state measured during the manufacturing process, and can also be rewritten as needed. Furthermore, by storing the full charge capacity of the secondary battery 301a in the memory 317, the remaining capacity can be calculated together with the control unit 310.

[0202] In the temperature detection unit 318, a temperature detection element 308 is used to measure the temperature, and to perform charge and discharge control when abnormal heating occurs, or to make corrections in the calculation of remaining capacity.

[0203] [B-2. Energy Storage System]

[0204] The secondary battery described in one embodiment of this disclosure can be installed in devices such as electronic devices, electric vehicles, electric aircraft, and energy storage devices, or used to supply electricity.

[0205] Examples of electronic devices include laptops, smartphones, tablets, PDAs (portable information terminals), mobile phones, wearable devices, cordless handsets, camcorders, digital still cameras, e-books, electronic dictionaries, music players, radios, headphones, game consoles, navigation systems, memory cards, pacemakers, hearing aids, power tools, electric shavers, refrigerators, air conditioners, televisions, stereo systems, water heaters, microwave ovens, dishwashers, washing machines, dryers, lighting equipment, toys, medical devices, robots, load conditioners, and signal lights.

[0206] In addition, examples of electric vehicles include railway vehicles, golf carts, electric trolleys, and electric vehicles (including hybrid vehicles), which can be used as a power source for their propulsion or auxiliary power. Examples of energy storage devices include power storage devices for buildings, such as residences, or for power generation equipment.

[0207] <C. Specific Topics>

[0208] (1-1)

[0209] [Structure] The positive electrode active material layer of the positive electrode in the method 1-1, which can be applied to batteries such as lithium-ion secondary batteries, is formed by attaching Zr (zirconium) or Ti (titanium) to the surface of positive electrode active material particles containing lithium nickel cobalt aluminum oxide (NCA) or nickel cobalt manganese oxide (NCM) with a Ni ratio of 85% or more. In this positive electrode active material, the concentration of Zr or Ti is relatively high near the surface of the positive electrode active material particles and relatively low inside the positive electrode active material particles.

[0210] Additionally, positive electrode active materials that can be used in the positive electrode of batteries such as lithium-ion secondary batteries (method 1-1) include, for example, LiNiO2 and LiNi. 0.9 Co 0.1 O2, LiNi 0.85 Co 0.1 Al 0.05 O2, LiNi 0.90 Co 0.05 Al 0.05 O2, LiNi 0.82 Co 0.14 Al 0.04 O2, LiNi 0.78 Co 0.18 Al 0.04 O2 and LiNi 0.90 Co 0.06 Al 0.04 O2, LiNi 0.5 Co 0.2 Mn 0.3O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.9 Co 0.05 Mn 0.05 O2, LiNi 0.3 Co 0.3 Mn 0.3 O2 and LiNi 0.84 Co 0.08 Mn 0.08 O2, LiNi 0.80 Co 0.10 Mn 0.05 Al 0.05 Lithium-nickel composite oxides such as O2 are used. The surface of this positive electrode active material is covered with boron compounds. That is, the positive electrode active material (positive electrode material) contains lithium-nickel composite oxides and boron compounds covering the surface of these lithium-nickel composite oxides. These boron compounds are a general term for compounds containing boron (B) as a constituent element. This is because the surface of the lithium-nickel composite oxide is electrochemically stable, thus inhibiting the decomposition reaction of the electrolyte on the surface of the lithium-nickel composite oxide. The types of boron compounds are not particularly limited, but include, for example, boric acid (H3BO3), lithium tetraborate (Li2B4O7), ammonium pentaborate (NH4B5O8), lithium metaborate (LiBO2), and boron oxide (B2O3).

[0211] (1-2)

[0212] [structure]

[0213] Figure 9A This is a cross-sectional schematic diagram showing a portion of the structure of the positive electrode 21 in methods 1-2, which can be applied to batteries such as lithium-ion secondary batteries. Figure 9A As shown, in the positive electrode 21 of methods 1-2, the positive electrode active material layer 21B includes a plurality of particles 21B-1 with relatively large diameters and a plurality of particles 21B-2 with relatively small diameters. Boric acid-containing coatings 21CL1 and 21CL2 are respectively disposed on the surfaces of particles 21B-1 and particles 21B-2. It should be noted that coatings 21CL1 and 21CL2 can cover at least a portion of the surface of particles 21B-1 and at least a portion of the surface of particles 21B-2. Alternatively, the amount of coating 21CL2 covering the surface of particles 21B-2 may be greater per unit surface area (by weight) than the amount of coating 21CL1 covering the surface of particles 21B-1.

[0214] [Effect]

[0215] According to the positive electrode 21 of method 1-2, by selectively covering a large amount of boric acid on small-diameter particles 21B-2 that are relatively easy to deteriorate, the deterioration of the positive electrode active material can be suppressed, thereby reducing the reaction resistance.

[0216] (1-3)

[0217] [structure]

[0218] Figure 9B This is a cross-sectional schematic diagram showing a portion of the structure of the positive electrode 21, which can be applied to batteries such as lithium-ion secondary batteries (methods 1-3). Figure 9B As shown, in the positive electrode 21 of methods 1-3, the positive electrode active material layer 21B includes a plurality of particles 21B-1 with relatively large diameters and a plurality of particles 21B-2 with relatively small diameters. Boric acid-containing coatings 21CL1 and 21CL2 are respectively disposed on the surfaces of particles 21B-1 and particles 21B-2. It should be noted that the coatings 21CL1 and 21CL2 can cover at least a portion of the surface of particles 21B-1 and at least a portion of the surface of particles 21B-2. Furthermore, in the positive electrode active material layer 21B, the coatings 21CL1 and 21CL2 are not present in the region of the first layer closest to the positive electrode current collector 21A. Additionally, in the positive electrode active material layer 21B, the amount of coatings 21CL1 and 21CL2 attached in the region of the nth layer furthest from the positive electrode current collector 21A, i.e., closest to the separator 23, is greater than the amount of coatings 21CL1 and 21CL2 attached in the region between the first layer and the nth layer. The amount of adhesion referred to herein is the weight per unit surface area of ​​the coating 21CL1 covering the surface of particle 21B-1, or the weight per unit surface area of ​​the coating 21CL2 covering the surface of particle 21B-2.

[0219] [Effect]

[0220] In the positive electrode active material layer 21B, the diffusion of Li ions is rapid in the nth layer closest to the separator 23, making it easy for the positive electrode active material to deteriorate. According to the positive electrode 21 of embodiments 1-5, since the amount of boric acid-containing coatings 21CL1 and 21CL2 attached to the nth layer closest to the separator 23 is greater than that of other layers, the deterioration of the positive electrode active material can be suppressed. Therefore, according to the positive electrode 21 of embodiments 1-3, the degradation of the reaction resistance after charge-discharge cycles in the region of the nth layer closest to the separator 23 in the positive electrode active material layer 21B can be suppressed, and the increase in reaction resistance in the region of the first layer closest to the positive electrode current collector 21A in the positive electrode active material layer 21B can also be suppressed.

[0221] (1-4)

[0222] [structure]

[0223] Figure 9C This is an enlarged cross-sectional schematic diagram showing the positive electrode active material particles 21B-1 and 21B-2 contained in the positive electrode active material layer 21B of methods 1-4, which can be applied to batteries such as lithium-ion secondary batteries. (Example) Figure 9C As shown, in the positive electrode active material layer 21B of methods 1-4, positive electrode active material particles 21B-1 covered by adhesive 21BD are mixed with positive electrode active material particles 21B-2 not covered by adhesive 21BD.

[0224] [Effect]

[0225] According to the positive electrode active material layer 21B of methods 1-4, high output can be expected. For example, the binder 21BD can be maintained at the contact point between the positive electrode active material particles 21B-1 and 21B-2. That is, the mechanical strength of the positive electrode active material layer 21B is maintained. On the other hand, since there are positive electrode active material particles 21B-2 that are not covered by the binder 21BD, good lithium ion intercalation and deintercalation can be achieved.

[0226] (2-1)

[0227] [structure]

[0228] Figure 10A This is a cross-sectional schematic diagram showing a portion of the structure of the positive electrode 21 in configuration 2-1-1, which can be applied to batteries such as lithium-ion secondary batteries. Figure 10A As shown, in the positive electrode 21 of method 2-1-1, the positive electrode active material layer 21B includes positive electrode active material particles 21B-1 composed of lithium nickel cobalt aluminum oxide (NCA), carbon nanotubes (CNTs), and acetylene black AB. The acetylene black AB is present near the interface between the positive electrode current collector 21A and the positive electrode active material layer 21B.

[0229] Figure 10B This is a cross-sectional schematic diagram showing a portion of the structure of the positive electrode 21 of method 2-1-2, which can be applied to batteries such as lithium-ion secondary batteries. Except for the absence of acetylene black AB, the structure of the positive electrode 21 of method 2-1-2 is substantially the same as that of the positive electrode 21 of method 2-1-1.

[0230] Figure 10C This is a cross-sectional schematic diagram showing a portion of the structure of the positive electrode 21 of method 2-1-3, which can be applied to batteries such as lithium-ion secondary batteries. Except that it does not contain carbon nanotubes (CNTs), and acetylene black AB is dispersed and exists in the positive electrode active material layer 21B except near the interface between the positive electrode current collector 21A and the positive electrode active material layer 21B, the structure of the positive electrode 21 of method 2-1-3 is substantially the same as that of the positive electrode 21 of method 2-1-1.

[0231] Figure 10D This is a cross-sectional schematic diagram showing a portion of the structure of the positive electrode 21 of method 2-1-4, which can be applied to batteries such as lithium-ion secondary batteries. Except for the portion near the interface between the positive current collector 21A and the positive active material layer 21B, where acetylene black AB is also dispersed in the positive active material layer 21B, the structure of the positive electrode 21 of method 2-1-4 is substantially the same as that of the positive electrode 21 of method 2-1-1.

[0232] [Effect]

[0233] Compared to the positive electrode active material layers 21B of methods 2-1-2 to 2-1-4, the positive electrode active material layer 21B according to method 2-1-1 achieves a balance between reducing the composite material resistance (the internal resistance of the positive electrode active material layer 21B) and reducing the interface resistance (the resistance at the interface between the positive electrode current collector 21A and the positive electrode active material layer 21B), and also obtains excellent loading characteristics. It can be considered that by dispersing carbon nanotubes (CNTs) throughout the positive electrode active material layer 21B, the diffusion path of Li ions can be ensured, and by placing acetylene black AB near the interface between the positive electrode current collector 21A and the positive electrode active material layer 21B, a good electron path can be formed.

[0234] (2-2)

[0235] [structure]

[0236] Figure 11A This is a cross-sectional schematic diagram showing a portion of the structure of the positive electrode 21 in method 2-2-1, which can be applied to batteries such as lithium-ion secondary batteries. Figure 11A As shown, in the positive electrode 21 of method 2-2-1, the positive electrode active material layer 21B includes positive electrode active material particles 21B-1 and 21B-2 composed of lithium nickel cobalt aluminum oxide (NCA), carbon nanotubes (CNTs) with a length of approximately 150 μm, and acetylene black AB. For example, acetylene black AB exists between multiple positive electrode active material particles 21B-1 and 21B-2. In the positive electrode 21 of method 2-2-1, the positive electrode active material layer 21B includes multiple particles 21B-1 with relatively large diameters and multiple particles 21B-2 with relatively small diameters.

[0237] Figure 11B This is a cross-sectional schematic diagram showing a portion of the structure of the positive electrode 21 of method 2-2-2, which can be applied to batteries such as lithium-ion secondary batteries. Except that the length of carbon nanotubes (CNTs) is less than 50 μm, the structure of the positive electrode 21 of method 2-2-2 is substantially the same as that of the positive electrode 21 of method 2-2-1.

[0238] [Effect]

[0239] According to the positive electrode 21 of method 2-2-1, compared with the positive electrode 21 of method 2-2-2, the positive electrode active material layer 21B contains carbon nanotubes (CNTs) with longer lengths. Therefore, the non-uniformity of electronic resistance in the positive electrode active material layer 21B can be reduced. In particular, it is possible to prevent the isolation of electronic paths of relatively small-diameter positive electrode active material particles and to mitigate the degradation caused by repeated charge and discharge.

[0240] (2-3)

[0241] [structure]

[0242] Figure 12A This is a cross-sectional schematic diagram showing a portion of the structure of the positive electrode active material layer 21B, which can be applied to batteries such as lithium-ion secondary batteries (method 2-3-1). Figure 12A As shown, the positive electrode active material layer 21B of method 2-3-1 comprises multiple positive electrode active material particles 21B-1, acetylene black AB as a spherical conductive additive, and carbon nanotubes (CNTs) as a linear conductive additive. The carbon nanotubes (CNTs) can be uniformly distributed throughout the positive electrode active material layer 21B by mixing a uniformly dispersed CNT dispersion with a positive electrode additive slurry and coating it onto the positive electrode current collector 21A during the manufacturing process of the positive electrode active material layer 21B. For example, the carbon nanotubes (CNTs) can have a length of 100 μm or more. The carbon nanotubes (CNTs) can be detected by observing the product obtained by SEM after diluting the positive electrode active material layer 21B with NMP (N-methyl-2-pyrrolidone) and then drying it.

[0243] Figure 12A This is a cross-sectional schematic diagram showing a portion of the structure of the positive electrode active material layer 21B of method 2-3-2, which can be applied to batteries such as lithium-ion secondary batteries. Except for the absence of carbon nanotubes (CNTs), the structure of the positive electrode 21 in method 2-3-2 is substantially the same as the structure of the positive electrode active material layer 21B in method 2-3-1.

[0244] [Effect]

[0245] Compared to the positive electrode active material layer 21B of Method 2-3-2, the positive electrode active material layer 21B of Method 2-3-1, by including both carbon nanotubes (CNTs) and acetylene black AB, can prevent the isolation of electron pathways in the positive electrode active material layer 21B and reduce the unevenness of internal resistance. Furthermore, since it also contains carbon nanotubes (CNTs) in addition to acetylene black AB, the total amount of acetylene black AB contained in the positive electrode active material layer 21B can be reduced. Therefore, the movement of Li ions becomes easier.

[0246] (2-4)

[0247] [structure]

[0248] Figure 13 This is a cross-sectional schematic diagram showing a portion of the structure of the positive electrode active material layer 21B, which can be applied to batteries such as lithium-ion secondary batteries (methods 2-4). Figure 13 As shown, the positive electrode active material layer 21B of methods 2-4 includes multiple positive electrode active material particles 21B-1, acetylene black AB as a spherical conductive aid, carbon nanotubes (CNTs) as a linear conductive aid, and conductive bridges (BGs). The bridges (BGs) connect adjacent positive electrode active material particles 21B-1 to each other. The bridges (BGs) can be, for example, Al (aluminum) powder, Al sheets, or aluminum fibers. Alternatively, the bridges (BGs) can also be structures in which the surface of Al (aluminum) powder, the surface of Al sheets, or the surface of aluminum fibers are respectively covered with a film of a fluorine compound. Besides Al, metals that do not decompose even at high potentials can also be used as structural materials for the bridges (BGs).

[0249] [Effect]

[0250] According to the positive electrode active material layer 21B of method 2-4, since multiple positive electrode active material particles 21B-1 are connected by bridges BG, the bonding between the positive electrode active material particles 21B-1 is enhanced compared with the positive electrode active material layer 21B without bridges BG, which can improve the mechanical strength of the positive electrode active material layer 21B. In addition, the isolation of positive electrode active material is reduced, and even if the positive electrode active material layer 21B is thickened, the reduction of load characteristics can be suppressed.

[0251] (2-5)

[0252] [structure]

[0253] The positive electrode current collector 21A of the positive electrode 21 in methods 2-5, which can be applied to batteries such as lithium-ion secondary batteries, is made of Al material, wherein the total purity mass of Si (silicon) and Fe (iron) is less than 0.05%, the purity mass of Cu (copper) is less than 0.1%, the purity mass of Mg (magnesium) is less than 0.1%, and the total purity mass of other elements is less than 0.05%. Furthermore, the Al material constituting the positive electrode current collector 21A in methods 2-5 has a purity mass of 238 W / m³. Thermal conductivity above C, with 70 kN / mm 2 The above refers to the longitudinal elastic modulus.

[0254] [Effect]

[0255] According to the positive current collector 21A of method 2-5, aluminum foil with high thermal conductivity (few impurities) is used. Therefore, the heat dissipation performance of the electrode winding 20 can be improved. That is, the heat generated inside the battery is effectively dissipated to the outside. As a result, the temperature rise of the electrode material and electrolyte is suppressed. In addition, since the increase in internal resistance can be suppressed, the energy supply from the battery and the charging and discharging speed are improved, thereby achieving high output. Furthermore, due to the improved heat dissipation performance, the temperature rise can be suppressed, and the excessive temperature rise and thermal stress of the electrode winding 20 can be reduced, thereby maintaining a stable operating state.

[0256] (2-6)

[0257] [structure]

[0258] Figure 14 This is a cross-sectional schematic diagram showing the structure of the positive electrode current collector 21A, which can be applied to batteries such as lithium-ion secondary batteries (methods 2-6). Figure 14 As shown, in the positive current collector 21A of methods 2-6, the surface 21AS1 and the back surface 21AS2 have concave and convex shapes, respectively. It should be noted that... Figure 14 The shapes of the surface 21AS1 and the back surface 21AS2 shown are one example, and this disclosure is not limited thereto. Furthermore, if the positive electrode active material layer 21B is formed only on the surface 21AS1, the back surface 21AS2 may not have an uneven shape. The uneven shapes of the surface 21AS1 and the back surface 21AS2 are formed, for example, by edge grinding.

[0259] [Effect]

[0260] According to the positive current collector 21A of methods 2-6, since the surface 21AS1 and the back surface 21AS2 have uneven shapes, the surface areas of the surface 21AS1 and the back surface 21AS2 can be increased. Therefore, the contact area at the interface between the positive current collector 21A and the positive active material layer 21B can be increased, and the resistance at the interface between the positive current collector 21A and the positive active material layer 21B can be reduced. In addition, by having uneven shapes, an anchoring effect can be obtained to maintain the positive active material layer 21B, and the detachment and peeling of the positive active material layer 21B from the positive current collector 21A can be suppressed.

[0261] (3-1)

[0262] [structure]

[0263] Figure 15 This is an enlarged cross-sectional view showing a portion of the structure of the positive electrode 21 in method 3-1, which can be applied to batteries such as lithium-ion secondary batteries. Figure 15As shown, the positive electrode 21 of method 3-1 has a positive current collector 21A, a positive active material layer 21B, a base layer 21C, and a masking layer 21D.

[0264] The positive current collector 21A may contain a conductive material such as aluminum. The positive current collector 21A may be a metal foil made of aluminum or an aluminum alloy. The positive current collector 21A is in a state where its end in the W direction, which is the width direction, is not covered by any of the positive active material layer 21B, the undercoating layer 21C, and the masking layer 21D and is exposed.

[0265] The structural material of the base coating 21C is, for example, carbon black or carbon nanotubes (CNTs). The base coating 21C covers both sides of the positive current collector 21A. Furthermore, the base coating 21C does not reach the front end T21A of the positive current collector 21A. That is, in the W direction, the position of the front end T21C of the base coating 21C is recessed inwards compared to the position of the front end T21A of the positive current collector 21A.

[0266] A positive electrode active material layer 21B is disposed on a base coating layer 21C. Furthermore, the positive electrode active material layer 21B does not reach the leading edge T21C in the base coating layer 21C. That is, in the W direction, the position of the leading edge T21B of the positive electrode active material layer 21B is recessed inwards compared to the position of the leading edge T21C of the base coating layer 21C. Therefore, the vicinity of the leading edge T21C of the base coating layer 21C is not covered by the positive electrode active material layer 21B. In the positive electrode 21 of embodiment 3-1, the vicinity of the boundary between the base coating layer 21C and the positive electrode active material layer 21B is covered by a masking layer 21D. Additionally, both the base coating layer 21C and the positive electrode active material layer 21B include portions not covered by the masking layer 21D. The masking layer 21D may be composed of an insulating material, such as a resin containing modified PVDF (polyvinylidene fluoride) or a copolymer of PVDF.

[0267] [Effect]

[0268] In the positive electrode 21 of method 3-1, the resistance is reduced due to the presence of the undercoating layer 21C, which suppresses heat generation during high-load charging and discharging. Furthermore, the improved heat dissipation due to the undercoating layer 21C further suppresses heat generation during high-load charging and discharging. Moreover, since a portion of the undercoating layer 21C is covered by the masking layer 21D, even when the positive electrode active material layer 21B becomes thicker, the difference in hardness between the positive electrode active material layer 21B and the masking layer 21D can prevent the positive electrode active material layer 21B from detaching from the positive electrode current collector 21A.

[0269] (3-2)

[0270] [structure]

[0271] In the positive electrode 21 of method 3-2, which can be applied to batteries such as lithium-ion secondary batteries, the undercoat 21C is composed of organic compounds such as non-fibrous conductive carbon, fibrous carbon, or particulate carbon, or inorganic compounds such as silicate compounds or aluminum hydrate oxides. When the undercoat 21C coated on the surface of the positive electrode current collector 21A, such as aluminum foil, or when the undercoat 21C, after being coated on the surface of the positive electrode current collector 21A and fired, is illuminated by an LED light source of 1,400,000 [lx] and captured by a CCD camera element, the brightness value of the undercoat 21C is 230 or less. It should be noted that the color of the undercoat 21C is not specified, but in RGB colors, ideally (i, i, i)i = 0~230.

[0272] [Effect]

[0273] In the positive electrode 21 of method 3-2, for example, the boundary position between the area coated with the base coating 21C and the area coated with the masking layer 21D, which is the upper layer of the base coating 21C, can be detected more accurately.

[0274] (4-1)

[0275] [structure]

[0276] Figure 16A This is an enlarged cross-sectional view showing a portion of the structure of the positive electrode 21 in method 4-1, which can be applied to batteries such as lithium-ion secondary batteries. Figure 16A As shown, the positive electrode 21 of method 4-1 has a positive current collector 21A, a positive active material layer 21B, a base layer 21C, and a masking layer 21D.

[0277] The positive current collector 21A contains, for example, a conductive material such as aluminum. The positive current collector 21A is, for example, a metal foil made of aluminum or an aluminum alloy. In the positive current collector 21A, the first end 21A1 in the W direction, which is the width direction, is bent.

[0278] The structural material of the base coating 21C is, for example, carbon black or carbon nanotubes (CNTs). The base coating 21C covers both sides of the positive current collector 21A. However, the base coating 21C does not reach the front end T21A of the first end 21A1 of the positive current collector 21A. That is, in the W direction, the position of the front end T21C of the base coating 21C is recessed inwards compared to the position of the front end T21A of the positive current collector 21A. Therefore, the vicinity of the front end T21A of the first end 21A1 of the positive current collector 21A is exposed and not covered by the base coating 21C.

[0279] A positive electrode active material layer 21B is disposed on a base coating layer 21C. Furthermore, the positive electrode active material layer 21B does not reach the leading edge T21C in the base coating layer 21C. That is, in the W direction, the position of the leading edge T21B of the positive electrode active material layer 21B is recessed inwards compared to the position of the leading edge T21C of the base coating layer 21C. Therefore, the vicinity of the leading edge T21C of the base coating layer 21C is not covered by the positive electrode active material layer 21B. In the positive electrode 21 of embodiment 4-1, the vicinity of the boundary between the base coating layer 21C and the positive electrode active material layer 21B is covered by a masking layer 21D. Additionally, both the base coating layer 21C and the positive electrode active material layer 21B include portions not covered by the masking layer 21D. The masking layer 21D may be composed of an insulating material, such as a resin containing modified PVDF (polyvinylidene fluoride) or a copolymer of PVDF.

[0280] [Effect]

[0281] In the positive electrode 21 of method 4-1, the resistance is reduced due to the presence of the undercoating 21C, which suppresses heat generation during high-load charging and discharging. Furthermore, the heat dissipation is improved due to the undercoating 21C, further suppressing heat generation during high-load charging and discharging. Moreover, since the undercoating 21C covers a portion of the bent first end 21A1 in the positive current collector 21A, heat diffusion is improved at the welding point between the positive current collector 21A and the positive current collector plate 24.

[0282] (4-2)

[0283] [structure]

[0284] Figure 16B This is an enlarged cross-sectional view showing a portion of the structure of the positive electrode 21 in method 4-2, which can be applied to batteries such as lithium-ion secondary batteries. Figure 16B As shown, in the positive electrode 21 of method 4-2, the position of the front end T21C of the base coating 21C is further inward and backward than the bending position T21A1 of the first end 21A1 of the positive current collector 21A. Apart from this, the structure of the positive electrode 21 of method 4-2 is similar to... Figure 16A The structure of the positive electrode 21 in the method 4-1 shown is essentially the same.

[0285] [Effect]

[0286] In the positive electrode 21 of method 4-2, by providing an undercoat 21C, heat dissipation can be improved and the undercoat 21C can be prevented from peeling off when the first end 21A1 of the positive current collector 21A is welded to the positive current collector plate 24.

[0287] (4-3)

[0288] [structure]

[0289] Figure 16CThis is an enlarged cross-sectional view showing a portion of the structure of the positive electrode 21 in method 4-3, which can be applied to batteries such as lithium-ion secondary batteries. Figure 16C As shown, in the positive electrode 21 of method 4-3, the front end T21C of the bottom coating 21C is positioned further inward and backward than the front end T21D of the masking layer 21D. Therefore, the bottom coating 21C is covered by the masking layer 21D and the positive electrode active material layer 21B. Apart from this, the structure of the positive electrode 21 of method 4-3 is similar to... Figure 16C The structure of the positive electrode 21 in the method 4-1 shown is essentially the same.

[0290] [Effect]

[0291] In the positive electrode 21 of method 4-3, the heat dissipation can be improved by providing the undercoating layer 21C, while the undercoating layer 21C can be protected by the masking layer 21D and the positive electrode active material layer 21B. Furthermore, since the undercoating layer 21C is also located below the masking layer 21D in the T direction (the thickness direction), peeling caused by the difference in hardness between the positive electrode active material layer 21B and the masking layer 21D can be suppressed when the positive electrode active material layer 21B is coated thickly. In addition, since the masking layer 21D is also in contact with the positive electrode current collector 21A, peeling can be effectively suppressed.

[0292] (4-4-1)

[0293] [structure]

[0294] Figure 17 This is an enlarged cross-sectional view showing a portion of the structure of the positive electrode 21 in method 4-4-1, which can be applied to batteries such as lithium-ion secondary batteries. Figure 17 As shown, in the positive electrode 21 of method 4-4-1, undercoating layers 21C-a and 21C-b, positive electrode active material layers 21B-a and 21B-b, and masking layers 21D-a and 21D-b are formed on both sides of the positive electrode current collector 21A (for convenience, referred to as side A and side B). In the positive electrode 21 of method 4-4-1, and... Figure 16C Similarly, in the positive electrode 21 of the shown method 4-3, the undercoating layers 21C-a and 21C-b are covered by the masking layers 21D-a and 21D-b and the positive electrode active material layers 21B-a and 21B-b.

[0295] In the positive electrode 21 of method 4-4-1, in the W direction, the position of the front end T21D-a of the masking layer 21D-a is set back from the position of the front end T21A of the positive current collector 21A; the position of the front end T21D-b of the masking layer 21D-b is set back from the position of the front end T21D-a; the position of the front end T21C-a of the bottom coating layer 21C-a is set back from the position of the front end T21D-b; the position of the front end T21C-b of the bottom coating layer 21C-b is set back from the position of the front end T21C-a; the position of the front end T21B-a of the positive active material layer 21B-a is set back from the position of the front end T21C-b; and the position of the front end T21B-b of the positive active material layer 21B-b is set back from the position of the front end T21B-a. Furthermore, in the W direction, the position of the rear end E21D-b of the masking layer 21D-b is set back from the position of the rear end E21D-a of the masking layer 21D-a. Furthermore, in the T direction corresponding to the thickness direction, the distance M-Ha between the surface of the masking layer 21D-a at the position of the front end T21C-a of the base coating 21C-a and the A surface of the positive current collector 21A is smaller than the distance M-Hb between the surface of the masking layer 21D-b at the position of the front end T21C-b of the base coating 21C-b and the B surface of the positive current collector 21A (M-Ha < M-Hb).

[0296] [Effect]

[0297] In the positive electrode 21 of method 4-4-1, in the W direction, compared with the position of the front end T21D-b of the masking layer 21D-b, the position of the front end T21D-a of the masking layer 21D-a is closer to the position of the front end T21A of the positive current collector 21A, and the distance from M-Ha is shorter than the distance from M-Hb, so it is easier to bend the first end of the positive current collector 21A. That is, it is easy to bend the positive current collector 21A with the position of the front end T21D-b as a fulcrum. Therefore, the bending stress is difficult to be transmitted to the bottom coatings 21C-a and 21D-b formed on both sides of the positive current collector 21A, and the peeling of the bottom coatings 21C-a and 21D-b can be suppressed.

[0298] In contrast, such as Figure 18A As shown in method 4-4-2A, in the W direction, compared to the position of the front end T21D-b of the masking layer 21D-b, the position of the front end T21D-a of the masking layer 21D-a is closer to the position of the front end T21A of the positive current collector 21A. When the thickness of the masking layer 21D-a is greater than the thickness of the masking layer 21D-b, bending the positive current collector 21A at the position of the front end T21D-b becomes difficult. Similarly, as... Figure 18BAs shown in method 4-4-2B, in the W direction, compared with the position of the front end T21D-a of the masking layer 21D-a, the position of the front end T21D-b of the masking layer 21D-b is closer to the position of the front end T21A of the positive current collector 21A. When the thickness of the masking layer 21D-b is greater than the thickness of the masking layer 21D-a, it becomes difficult to bend the positive current collector 21A at the position of the front end T21D-a.

[0299] (4-4-3A)

[0300] [structure]

[0301] Figure 19A This is an enlarged cross-sectional view showing a portion of the structure of the positive electrode 21 in configuration 4-4-3A, which can be applied to batteries such as lithium-ion secondary batteries. In the positive electrode 21 of configuration 4-4-3A, in the W direction, the position of the front end T21D-a of the masking layer 21D-a is substantially the same as the position of the front end T21D-b of the masking layer 21D-b. Furthermore, the position of the front end T21C-a of the undercoating layer 21C-a is closer to the front end T21A of the positive current collector 21A than the position of the front end T21C-b of the undercoating layer 21C-b. In this case, the thickness of the masking layer 21D-a can be thinner than the thickness of the masking layer 21D-b.

[0302] [Effect]

[0303] In the positive electrode 21 of method 4-4-3A, in the W direction, the position of the front end T21D-a of the masking layer 21D-a is substantially the same as the position of the front end T21D-b of the masking layer 21D-b, and the distance from M-Ha is shorter than the distance from M-Hb, so it is easy to bend the first end of the positive electrode current collector 21A. That is, it is easy to bend the positive electrode current collector 21A using the positions of the front ends T21D-a and T21D-b as fulcrums. Therefore, bending stress is difficult to be transmitted to the undercoating layers 21C-a and 21D-b formed on both sides of the positive electrode current collector 21A, and the peeling of the undercoating layers 21C-a and 21D-b can be suppressed.

[0304] (4-4-3B)

[0305] [structure]

[0306] Figure 19BThis is an enlarged cross-sectional view showing a portion of the structure of the positive electrode 21 in method 4-4-3B, which can be applied to batteries such as lithium-ion secondary batteries. In the positive electrode 21 of method 4-4-3B, in the W direction, the position of the front end T21D-b of the masking layer 21D-a is closer to the front end T21A of the positive current collector 21A than the position of the front end T21D-a of the masking layer 21D-a. Furthermore, the position of the front end T21C-a of the bottom coating layer 21C-a is closer to the front end T21A of the positive current collector 21A than the position of the front end T21C-b of the bottom coating layer 21C-b. In this case, the thickness of the masking layer 21D-b can be thinner than the thickness of the masking layer 21D-a.

[0307] [Effect]

[0308] In the positive electrode 21 of method 4-4-3B, in the W direction, compared with the distance between the position of the front end T21D-a of the masking layer 21D-a and the position of the front end T21A of the positive current collector 21A, the distance between the position of the front end T21D-b of the masking layer 21D-a and the position of the front end T21A of the positive current collector 21A is closer, and the distance M-Hb is shorter than the distance M-Ha. Therefore, it is easy to bend the first end of the positive current collector 21A. That is, it is easy to bend the positive current collector 21A with the position of the front end T21D-a as a fulcrum. The bending stress of the undercoating layers 21C-a and 21D-b formed on both sides of the positive current collector 21A becomes difficult to transmit, and the peeling of the undercoating layers 21C-a and 21D-b can be suppressed.

[0309] (4-5)

[0310] [structure]

[0311] Figure 20 This is an enlarged cross-sectional view showing a portion of the structure of the positive electrode 21, which can be applied to batteries such as lithium-ion secondary batteries (methods 4-5). Figure 20 As shown, in the positive electrode 21 of method 4-5, in the W direction, the position of the front end T21C of the bottom coating 21C is recessed inwards compared to the positions of the front end T21D of the masking layer 21D and the front end T21B of the positive electrode active material layer 21B. Therefore, the bottom coating 21C is covered by the masking layer 21D and the positive electrode active material layer 21B. Apart from this, the structure of the positive electrode 21 of method 4-5 is substantially the same as the structure of the positive electrode 21 of method 4-1 shown in Figure 4-1. It should be noted that in method 4-5, in the W direction, the position of the front end T21D of the masking layer 21D is closer to the front end T21A of the positive electrode current collector 21A than the position of the front end T21B of the positive electrode active material layer 21B.

[0312] [Effect]

[0313] In the positive electrode 21 of method 4-5, a base coating 21C is also provided, which reduces resistance and suppresses heat generation during high-load charging and discharging. Furthermore, the presence of the base coating 21C improves heat dissipation, further suppressing heat generation during high-load charging and discharging. Moreover, in the positive electrode 21 of method 4-5, the leading edge T21C of the base coating 21C is located further back than the leading edge T21B of the positive electrode active material layer 21B. Therefore, by mitigating the reduction in end-area density caused by coating collapse of the positive electrode active material layer 21B, or the unevenness in volume density of the positive electrode active material layer 21B caused by the coverage of the masking layer 21D, a more uniform battery reaction can be expected.

[0314] (4-6)

[0315] [structure]

[0316] Figure 21A This is an enlarged cross-sectional view showing a portion of the structure of the positive electrode 21 in a battery type 4-6A, which can be applied to batteries such as lithium-ion secondary batteries. Figure 21A As shown, in the positive electrode 21 of methods 4-6A, the formation positions of the positive electrode active material layers 21B-a and 21B-b are defined to coincide with the formation positions of the base coating layers 21C-a and 21C-b. Specifically, in the W direction, the front end T21B-a of the positive electrode active material layer 21B-a is set at a position receding from the front end T21A of the positive electrode current collector 21A compared to the position of the front end T21C-a of the base coating layer 21C-a formed on the surface of the positive electrode current collector 21A (for convenience, referred to as surface A). In the W direction, the front end T21B-b of the positive electrode active material layer 21B-b is set at a position receding from the front end T21A of the positive electrode current collector 21A compared to the position of the front end T21C-b of the base coating layer 21C-b formed on the back side of the positive electrode current collector 21A (for convenience, referred to as surface B). Here, as Figure 21A As shown, in the W direction, when the position of the front end T21C-a is closer to the front end T21A of the positive current collector 21A than the position of the front end T21C-b, the position of the front end T21B-a is closer to the front end T21A of the positive current collector 21A than the position of the front end T21B-b.

[0317] [Effect]

[0318] In the positive electrode 21 of method 4-6A, a base coating 21C is also provided, which reduces resistance and suppresses heat generation during high-load charging and discharging. Furthermore, the base coating 21C improves heat dissipation, further suppressing heat generation during high-load charging and discharging. In addition, it ensures the stability (straightness and areal density stability) of the front end T21B-a of the positive electrode active material layer 21B-a and the front end T21B-b of the positive electrode active material layer 21B-b in the L direction and the W direction. Furthermore, it ensures the peelability of the base coating 21C.

[0319] In contrast, for example, such as Figure 21B As shown, when the position of the front end T21B-a of the positive electrode active material layer 21B-a is closer to the front end T21A of the positive electrode current collector 21A than the position of the front end T21C-a of the bottom coating layer 21C-a, or for example as... Figure 21C As shown, when the position of the front end T21B-b of the positive electrode active material layer 21B-b is closer to the front end T21A of the positive electrode current collector 21A than the positions of the front end T21C-a of the bottom coating layer 21C-a and the front end T21C-b of the bottom coating layer 21C-b, it is difficult to expect the above-mentioned effect.

[0320] (4-7)

[0321] [structure]

[0322] Figure 22A This is a planar diagram showing a portion of the structure of the positive electrode 21 in method 4-7A, which can be applied to batteries such as lithium-ion secondary batteries. (Example) Figure 22A As shown, in the positive electrode 21 of method 4-7A, the leading edge T21B of the positive electrode active material layer 21B in the W direction extends in a roughly straight line along the L direction, which is the long side direction of the positive electrode 21. Specifically, the position of the leading edge T21B in the W direction may converge within a range of ±50 μm relative to a reference position.

[0323] [Effect]

[0324] When bending the exposed portion of the positive current collector 21A that is not covered by the positive active material layer 21B, for example... Figure 22B Compared to the case in the positive electrode 21 of method 4-7B, where the front end T21B of the positive electrode active material layer 21B in the W direction has unevenness in the L direction, the case in the positive electrode 21 of method 4-7A, where the front end T21B has high flatness in the L direction, makes it difficult for stress to concentrate on the positive electrode current collector 21A near the front end T21B. Therefore, damage to the positive electrode current collector 21A can be avoided.

[0325] (4-8)

[0326] [structure]

[0327] Figure 23A This is a cross-sectional schematic diagram showing a portion of the structure of an electrode winding 20 that can be applied to batteries such as lithium-ion secondary batteries (method 4-8A). Figure 23A As shown, in the electrode winding 20 of method 4-8A, a portion of the negative electrode current collector 22A exposed on the end face opposite to the negative electrode current collector 25 is covered by the undercoating 22C. That is, on the end face of the electrode winding 20 opposite to the negative electrode current collector 25, the edge of the undercoating 22C extends further toward the negative electrode current collector 25 than the edge of the negative electrode active material layer 22B.

[0328] Figure 23B This is a cross-sectional schematic diagram showing a portion of the structure of the electrode winding 20, which can be applied to batteries such as lithium-ion secondary batteries (method 4-8B). Figure 23B As shown, in the electrode winding 20 of method 4-8B, similarly to the electrode winding 20 of method 4-8A, a portion of the negative current collector 22A exposed on the end face opposite to the negative current collector plate 25 is covered by the undercoating 22C. That is, on the end face of the electrode winding 20 opposite to the negative current collector plate 25, the edge of the undercoating 22C extends further toward the negative current collector plate 25 than the edge of the negative active material layer 22B. In particular, in method 4-8B, the undercoating 22C extends closer to the negative current collector plate 25 than the position where the negative current collector 22A is bent.

[0329] Figure 23C This is a cross-sectional schematic diagram showing a portion of the structure of the electrode winding 20, as in the reference example 4-8C. (See diagram below.) Figure 23C As shown, in the electrode winding body 20 of mode 4-8C, on the end face of the electrode winding body 20 opposite to the negative electrode current collector 25, the end edge of the negative electrode active material layer 22B coincides with the end edge of the bottom coating layer 22C.

[0330] [Effect]

[0331] In the electrode winding body 20 of method 4-8C, when the negative current collector 22A is welded to the negative current collector plate 25, the negative current collector 22A is stretched due to the expansion of the electrode winding body 20. Therefore, damage such as cracking may occur on the negative current collector 22A. According to the electrode winding body 20 of methods 4-8A and 4-8B, since the negative current collector 22A is reinforced by the base coating 22C, damage to the negative current collector 22A can be avoided. In particular, according to the electrode winding body 20 of method 4-8B, the negative current collector 22A is further reinforced, so it is preferred.

[0332] (4-9)

[0333] [structure]

[0334] Figure 24 This is an enlarged cross-sectional view showing a portion of the structure of the positive electrode 21, which can be applied to batteries such as lithium-ion secondary batteries (methods 4-9). Figure 24 As shown, in the positive electrode 21 of methods 4-9, in the W direction, the thickness of the bottom coating 21C-a and 21C-b is thicker as it moves further away from the front end T21B-a and T21B-b of the positive electrode active material layer 21B.

[0335] [Effect]

[0336] In the positive electrode 21 of methods 4-9, undercoating layers 21C-a and 21C-b are also provided, thus reducing resistance and suppressing heat generation during high-load charging and discharging. Furthermore, the undercoating layers 21C-a and 21C-b improve heat dissipation, further suppressing heat generation during high-load charging and discharging. Moreover, in the positive electrode 21 of methods 4-9, the thickness of the undercoating layers 21C-a and 21C-b increases further away from the front ends T21B-a and T21B-b of the positive electrode active material layer 21B, while the thickness of the positive electrode active material layer 21B-a and 21B-b decreases further away from the front ends T21B-a and T21B-b. Therefore, the resistance at locations far from the exposed portion of the positive electrode current collector 21A welded to the positive electrode current collector plate 24 can be reduced, resulting in a more uniform electrode reaction in the W direction.

[0337] (4-10)

[0338] [structure]

[0339] Figure 25 This is an enlarged cross-sectional view showing a portion of the structure of the positive electrode 21 in six types 4-10(A) to (F) that can be applied to batteries such as lithium-ion secondary batteries. The positive electrode 21 in types 4-10(A) to (F) each has a structure in which a base coating 21C and a positive electrode active material layer 21B are sequentially stacked on both sides of the positive electrode current collector 21A. In the positive electrode 21 of types 4-10(A) to (F), the positive electrode current collector 21A includes a first edge T21A and a second edge E21A in the W direction, and a region near the first edge T21A is exposed and not covered by either the base coating 21C or the positive electrode active material layer 21B.

[0340] like Figure 25 As shown in (A), in the positive electrode 21 of mode 4-10 (A), in the W direction, the thickness of the undercoating 21C is thinner the further away from both the first end edge T21A and the second end edge E22A of the positive current collector 21A, and is thinnest near the middle of the first end edge T21A and the second end edge E22A.

[0341] like Figure 25As shown in (B), in the positive electrode 21 of mode 4-10 (B), in the W direction, the thickness of the undercoating 21C is thicker the further away from both the first end edge T21A and the second end edge E22A of the positive current collector 21A, and is thickest near the middle of the first end edge T21A and the second end edge E22A.

[0342] like Figure 25 As shown in (C), in the positive electrode 21 of mode 4-10 (C), in the W direction, the base coating 21C has a relatively thick portion near both the first end edge T21A and the second end edge E22A of the positive current collector 21A, and a relatively thin portion near the middle of the first end edge T21A and the second end edge E22A.

[0343] like Figure 25 As shown in (D), in the positive electrode 21 of mode 4-10 (D), in the W direction, the undercoating 21C has a relatively thin portion near both the first end edge T21A and the second end edge E22A of the positive current collector 21A, and a relatively thick portion near the middle of the first end edge T21A and the second end edge E22A.

[0344] like Figure 25 As shown in (E), in the positive electrode 21 of method 4-10 (E), the thickness of the undercoat 21C is formed to be approximately constant in the W direction. In the regions near both the first end edge T21A and the second end edge E22A of the positive current collector 21A, an additional undercoat 21C2 is selectively formed on the undercoat 21C. The composition of the undercoat 21C is different from that of the undercoat 21C2. The binder ratio of the undercoat 21C is, for example, 1% relative to the entire undercoat 21C, while the binder ratio of the undercoat 21C2 is, for example, 0.5% relative to the entire undercoat 21C2. The undercoat 21C in contact with the positive current collector 21A preferably has a ratio that ensures good adhesion to the positive current collector 21A, and the binder ratio of the undercoat 21C2 is lower than that of the undercoat 21C to reduce resistance in the thickness direction. Since the base coating 21C is in contact with the positive current collector 21A, in order to reduce the resistance in the planar direction, a powdered conductive material such as acetylene black is preferred, and in order to form a conductive path in the thickness direction, a fibrous conductive material such as carbon nanotubes is preferred for the base coating 21C2.

[0345] like Figure 25 As shown in (F), in the positive electrode 21 of mode 4-10 (F), the thickness of the undercoat 21C is formed to be approximately constant in the W direction, and in the middle region of the W direction, another undercoat 21C2 is selectively formed on the undercoat 21C.

[0346] In a battery having an electrode winding body 20 with a positive electrode 21 using the methods described in 4-10(A) to (F) above, current collectors are disposed at both ends in the W direction. In the electrode winding body 20, the current collection efficiency is higher near the current collectors, decreasing as it moves away from them. Therefore, compared to the positive electrode 21 of methods 4-10(B) and 4-10(D), where the thickness of the base coating 21C in the middle region away from the current collector is greater than the thickness of the base coating 21C in the two end regions near the current collector, as in the positive electrode 21 of methods 4-10(A) and 4-10(C), where the thickness of the base coating 21C in the two end regions near the current collector is greater than the thickness of the base coating 21C in the middle region away from the current collector, the unevenness of current collection efficiency in the W direction can be reduced. As a result, capacity reduction during charge-discharge cycles can be suppressed, and heat generation during high-load operation can be uniformized, thus suppressing battery degradation. Regarding the undercoating 21C with a thickness-sloping portion in the positive electrode 21 of method 4-10(A), it can be formed, for example, by varying the coating amount in stages in the W direction. Alternatively, as with the positive electrode 21 of method 4-10(C), the undercoating 21C with a relatively larger thickness at both ends than in the middle region in the W direction can be formed, for example, by applying an undercoating of a certain thickness overall, and then selectively applying additional undercoating only at both ends.

[0347] (4-11)

[0348] [structure]

[0349] Figure 26 This is an enlarged cross-sectional view showing a portion of the structure of the positive electrode 21, which can be applied to batteries such as lithium-ion secondary batteries (method 4-11). Figure 26 As shown, in the positive electrode 21 of method 4-11, in the W direction, the position of the front end T21D of the masking layer 21D is located between the position of the front end T21A of the positive current collector 21A and the position of the front end T21C of the base coating 21C. Furthermore, in the W direction, the position of the front end T21C of the base coating 21C is located between the position of the front end T21D of the masking layer 21D and the position of the front end T21B of the positive active material layer 21B. Here, the thickness M-Ha of the portion of the masking layer 21D directly covering the positive current collector 21A is thinner than the combined thickness M-Hb of the portion of the masking layer 21D covering the base coating 21C and the base coating 21C. Additionally, the thickness M-Hb is thinner than the combined thickness M-Hc of the portion of the masking layer 21D covering both the base coating 21C and the positive active material layer 21B.

[0350] [Effect]

[0351] In the positive electrode 21 of method 4-11, the resistance is reduced due to the presence of the undercoating layer 21C, which suppresses heat generation during high-load charging and discharging. Furthermore, the heat dissipation is improved due to the undercoating layer 21C, further suppressing heat generation during high-load charging and discharging. Additionally, the undercoating layer 21C can be protected by the masking layer 21D. Moreover, since the front end T21B of the positive electrode active material layer 21B is covered by the masking layer 21D, the shedding of the positive electrode active material layer 21B is prevented. Furthermore, since a portion of the exposed portion of the positive electrode current collector 21A is directly covered by the masking layer 21D, winding misalignment in the electrode winding body 20 is prevented.

[0352] (4-12)

[0353] In the positive electrode 21 described in methods 4-1 to 4-11 above, the areal density (or thickness) of the undercoating 21C-a formed on surface A of the positive electrode current collector 21A can be different from the areal density (or thickness) of the undercoating 21C-b formed on surface B of the positive electrode current collector 21A. For example, in the high-curvature bent portion located at the winding center of the electrode winding body 20, the thickness of the positive electrode active material layer 21B provided on the surface of the positive electrode current collector 21A on the winding center side is increased, thereby increasing the areal density (or thickness) of the undercoating 21C. As a result, the resistance is reduced, the potential distribution is adjusted, and the heat distribution is made more uniform. As a result, a longer lifespan can be expected.

[0354] (4-13)

[0355] [structure]

[0356] Figure 27 This is an enlarged cross-sectional view showing a portion of the structure of the positive electrode 21 in method 4-13, which can be applied to batteries such as lithium-ion secondary batteries. Figure 27 As shown, in the positive electrode 21 of method 4-13, the undercoating 21C is provided only on one side of the positive current collector 21A (e.g., the side facing the winding center of the electrode winding 20). The side of the positive current collector 21A without the undercoating 21C is welded to the positive current collector plate 24. In the W direction, the position of the leading edge T21C of the undercoating 21C can, for example, be substantially the same as the position of the leading edge T21A of the positive current collector 21A. Furthermore, in the W direction, the position of the leading edge T21D of the masking layer 21D is located behind both the positions of the leading edge T21A of the positive current collector 21A and the leading edge T21C of the undercoating 21C. Additionally, in the W direction, the position of the leading edge T21D of the masking layer 21D is, for example, located between the leading edge T21C of the undercoating 21C and the leading edge T21B of the positive active material layer 21B. The undercoating 21C is, for example, composed of small carbon particles.

[0357] [Effect]

[0358] In the positive current collector 21A, when some damage exists on the surface of the electrode winding body 20 at the winding center, the positive current collector 21A is prone to cracking during the fabrication of the electrode winding body 20 and during subsequent charge-discharge cycles. Therefore, by providing a base coating 21C composed of small particles of carbon, stress concentration caused by large particles of active material contained in the positive active material layer 21B during pressing is reduced, making it difficult for the positive current collector 21A to crack and break. It should be noted that in the positive electrode 21 of methods 4-13, the base coating 21C can also be applied to the entire single surface of the positive current collector 21A (or a non-patterned base coating 21C).

[0359] (4-14)

[0360] [structure]

[0361] Figure 28A This is an enlarged cross-sectional view showing a portion of the structure of the positive electrode 21 in method 4-14, which can be applied to batteries such as lithium-ion secondary batteries. Specifically, Figure 28A The image was obtained by observing a 3mm × 3mm cross-section of the interface between the positive electrode 21 (process 4-14) and the positive electrode current collector 21A and the base coating 21C, which was fabricated by cutting the positive electrode 21 using a razor blade or an ion milling device at 2000x magnification using an electron microscope. Additionally, Figure 28A The bulk density of the positive electrode 21 shown is 3.0 g / cm³. 3 That's all. Here, it could also be, in Figure 28A In the image shown, when the three positions are viewed from a 60μm×40μm perspective, the ratio (FL / CL) of the length CL of the part of the positive electrode active material layer 21B that is in direct contact with the positive electrode current collector 21A to the length FL of the positive electrode current collector 21A is less than 20%.

[0362] [Effect]

[0363] In order to suppress the interfacial resistance between the positive current collector 21A and the positive active material layer 21B, there is a method of using a base coating 21C made of carbon material. Figure 28B This is a characteristic graph showing the relationship between the presence or absence of carbon coating 21C and the interfacial resistance between the positive current collector 21A and the positive active material layer 21B. (For example...) Figure 28BAs shown, the presence of the undercoat 21C reduces the interfacial resistance and composite material resistance. Therefore, compared to the case where the positive current collector 21A and the positive active material layer 21B are in direct contact, it is more ideal to insert the undercoat 21C between the positive current collector 21A and the positive active material layer 21B. Furthermore, depending on the compression conditions during the pressing process of manufacturing the positive electrode 21, the positive active material layer 21B may penetrate the carbon coating 21C and contact the positive current collector 21A. In this case, the interfacial resistance and composite material resistance increase. Therefore, the ratio FL / CL, representing the proportion of the positive active material layer 21B penetrating the undercoat 21C and contacting the positive current collector 21A, is ideally 20% or less. If it is 20% or less, a significant reduction in both interfacial resistance and composite material resistance can be expected.

[0364] (4-15)

[0365] [structure]

[0366] Figure 29A This is an enlarged cross-sectional view showing a portion of the structure of the electrode winding 20, which can be applied to batteries such as lithium-ion secondary batteries (method 4-15-1). Figure 29A As shown, in the electrode winding body 20 of method 4-15-1, the positive electrode 21 includes a positive current collector 21A, a base coating 21C disposed on both sides of the positive current collector 21A, and a positive active material layer 21B disposed on the base coating 21C, but does not have a masking layer. A portion of the positive current collector 21A is not covered by either the base coating 21C or the positive active material layer 21B, but is exposed. That is, in the W direction, the leading edge T21C of the base coating 21C is located at a position regressed from the position of the leading edge T21A of the positive current collector 21A. Furthermore, in the W direction, the leading edge T21B of the positive active material layer 21B is located at a position regressed from the position of the leading edge T21C. In addition, a negative electrode 22 is disposed on the opposite side of the positive electrode 21 in the T direction, separated by a separator 23. In the negative electrode 22, a negative active material layer 22B is disposed on both sides of the negative current collector 22A. In the W direction, the position of the front end T22B of the negative electrode active material layer 22B is located between the position of the front end T21C and the position of the front end T21B.

[0367] Figure 29B This is an enlarged cross-sectional view showing a portion of the structure of the electrode winding 20, which can be applied to batteries such as lithium-ion secondary batteries (method 4-15-2). Figure 29B In the electrode winding 20 of embodiment 4-15-2 shown, a ceramic coating CCS is provided on the surface of the diaphragm 23 opposite to the positive electrode 21. Apart from this, the structure of the electrode winding 20 of embodiment 4-15-2 is substantially the same as that of the electrode winding 20 of embodiment 4-15-1.

[0368] Figure 29C This is an enlarged cross-sectional view showing a portion of the structure of the electrode winding 20, which can be applied to batteries such as lithium-ion secondary batteries (method 4-15-3). Figure 29C In the electrode winding 20 of method 4-15-3 shown, the undercoating 21C is only disposed near the front end T21B of the positive electrode active material layer 21B. Apart from this, the structure of the electrode winding 20 of method 4-15-3 is substantially the same as that of the electrode winding 20 of method 4-15-2.

[0369] [Effect]

[0370] In the positive electrode 21 of methods 4-15-1 to 3, the resistance is reduced due to the presence of the undercoating layer 21C, which suppresses heat generation during high-load charging and discharging. Furthermore, the heat dissipation is improved due to the undercoating layer 21C, further suppressing heat generation during high-load charging and discharging. Moreover, since there is no masking layer covering the undercoating layer 21C and the positive electrode active material layer 21B, it is suitable for increasing energy density compared to cases with a masking layer, and the manufacturing process is simplified.

[0371] (4-16)

[0372] [structure]

[0373] Figure 30 (A) is an enlarged cross-sectional view showing the structure of the positive electrode 21, which can be applied to batteries such as lithium-ion secondary batteries (method 4-16). Additionally, Figure 30 (B) is a planar schematic diagram showing the structure of the positive electrode 21 in configuration 4-16. In the positive electrode 21 of configuration 4-16, the laser absorption rate of the undercoating 21C is higher than that of the positive current collector 21A. In the region of the positive current collector 21A that is covered by the undercoating 21C but not by the positive active material layer 21B, multiple locations indicated by arrows are cut off by laser irradiation.

[0374] [Effect]

[0375] By coating the positive current collector 21A with a base coating 21C that has a high laser absorption rate before processing, the deterioration and deformation of the positive current collector 21A caused by the heat generated during laser cutting can be suppressed. As a result, laser cutting can be performed effectively.

[0376] (5-1)

[0377] [structure]

[0378] Figure 31This is a schematic diagram showing the positive electrode active material particles 21BP and polyvinylidene fluoride (PVdF) contained in the positive electrode active material layer 21B of method 5-1, which can be applied to batteries such as lithium-ion secondary batteries. PVdF is obtained by making it porous through phase separation during drying. For example, it is obtained by adding NMP (N-methyl-2-pyrrolidone) and TEG (triethylene glycol) as a poor solvent to PVdF.

[0379] [Effect]

[0380] According to Method 5-1, the flexibility of the positive electrode active material layer 21B is improved by making the PVdF porous. Therefore, a thicker film of the positive electrode active material layer 21B can be achieved. That is, even with increased thickness, the positive electrode active material layer 21B maintains high flexibility, allowing for smooth winding during the fabrication of the electrode winding body 20. Furthermore, by making the PVdF porous, channels for lithium ions within the positive electrode active material layer 21B can be ensured. Therefore, the ion resistance of the electrode winding body 20 can be reduced, and further high output can be expected.

[0381] (5-2)

[0382] [structure]

[0383] Figure 32 This is a schematic diagram illustrating the positive electrode 21 of method 5-2, which can be applied to batteries such as lithium-ion secondary batteries, and the positive electrode active material particles 21BP and polyvinylidene fluoride (PVdF) contained in the positive electrode active material layer 21B. (See diagram for example.) Figure 32 As shown, the positive electrode 21 of embodiment 5-2 includes a positive current collector 21A and a positive active material layer 21B disposed on both sides thereof. The positive active material layer 21B includes a first region 21B1 and a second region 21B2 sequentially from the positive current collector 21A side.

[0384] The first region 21B1 has multiple positive electrode active material particles 21BP connected via a gel-like PVdF. The second region 21B2 has multiple positive electrode active material particles 21BP connected via a porous PVdF.

[0385] [Effect]

[0386] According to the positive electrode active material layer 21B of method 5-2, since the second region 21B2 has porous PVdF, it has high flexibility. Therefore, it is possible to achieve a thick film of the positive electrode active material layer 21B. That is, even if the thickness of the positive electrode active material layer 21B increases, the positive electrode active material layer 21B still has high flexibility, so the winding operation can be performed smoothly when fabricating the electrode winding body 20. In addition, by making the PVdF porous, the lithium ion channel in the second region 21B2 can be ensured. Therefore, the ion resistance of the electrode winding body 20 can be reduced, and further high output can be expected. On the other hand, since the first region 21B1 contains unporous gel-like PVdF, a high adhesion between the first region 21B1 and the positive electrode current collector 21A can be obtained, thereby preventing the positive electrode active material layer 21B from peeling off and falling off from the positive electrode current collector 21A.

[0387] (5-3)

[0388] [structure]

[0389] Figure 33 This is a cross-sectional schematic diagram of the positive electrode 21, which can be applied to batteries such as lithium-ion secondary batteries (method 5-3). Figure 33 As shown, the positive electrode 21 of embodiment 5-3 includes a positive current collector 21A and a positive active material layer 21B disposed on both sides thereof. The positive active material layer 21B includes a first region 21B1 and a second region 21B2 sequentially from the positive current collector 21A side.

[0390] Here, the proportion of adhesives such as PVdF contained in the second region 21B2 is higher than the proportion of adhesives such as PVdF contained in the first region 21B1.

[0391] [Effect]

[0392] According to the positive electrode active material layer 21B of method 5-3, the content of binder in the second region 21B2 located on the surface of the positive electrode 21 is increased relative to the positive electrode active material. For example, the surface of the positive electrode 21 is a region where stress tends to concentrate during winding for manufacturing the electrode winding body 20. By increasing the binder ratio near the surface of the positive electrode 21, the generation of cracks in the positive electrode active material layer 21B can be effectively prevented. In addition, compared to the case where a large amount of binder is evenly dispersed throughout the positive electrode active material layer 21B, the binder content can be reduced.

[0393] (5-4)

[0394] [structure]

[0395] Figure 34 This is a cross-sectional schematic diagram of the positive electrode 21, which can be applied to batteries such as lithium-ion secondary batteries (method 5-4). Figure 34 As shown, the positive electrode 21 of embodiment 5-4 includes a positive current collector 21A and a positive active material layer 21B disposed on its surface. The positive active material layer 21B includes a first region 21B1 and a second region 21B2 sequentially from the positive current collector 21A side.

[0396] Here, the proportion of adhesives such as PVdF contained in the first region 21B1 is higher than the proportion of adhesives such as PVdF contained in the second region 21B2.

[0397] [Effect]

[0398] According to the positive electrode active material layer 21B of method 5-4, the ratio of adhesive in the first region 21B1 adjacent to the positive electrode current collector 21A is higher than the ratio of adhesive in the second region 21B2. Therefore, the adhesion between the positive electrode current collector 21A and the positive electrode active material layer 21B can be improved, and the positive electrode active material layer 21B can be made more difficult to peel off from the positive electrode current collector 21A. That is, the peel strength of the positive electrode active material layer 21B can be improved. As a result, improved loading characteristics can be expected. Furthermore, compared to the case where a large amount of adhesive is evenly dispersed throughout the positive electrode active material layer 21B, the adhesive content can be reduced.

[0399] (5-5)

[0400] [structure]

[0401] Figure 35 This is a cross-sectional schematic diagram of the electrode winding 20, which can be applied to batteries such as lithium-ion secondary batteries (method 5-5). Figure 35 As shown, the electrode winding body 20 of embodiment 5-5 is formed by winding a laminated structure consisting of a positive electrode 21 and a negative electrode 22 separated by a separator. The negative electrode 22 is located at the innermost periphery of the electrode winding body 20. The positive electrode 21 includes a positive current collector 21A and positive active material layers 21B disposed on both sides thereof. Here, the positive active material layer 21B has a thick film portion 21B-A with a relatively large thickness and a thin film portion 21B-B with a relatively small thickness, which are alternately arranged in the winding direction. The thin film portion 21B-B is located outside the outermost periphery of the electrode winding body 20, for example, extending in a width direction orthogonal to the winding direction.

[0402] [Effect]

[0403] According to the positive electrode active material layer 21B of method 5-5, since a thin film portion 21B-B is provided, the expansion of the electrode winding 20 that accompanies the expansion of the negative electrode 22 during charging can be mitigated. As a result, a portion of the positive electrode 21 can be prevented from buckling toward the through hole 26 located at the center of the electrode winding 20.

[0404] (5-6)

[0405] [structure]

[0406] Figure 36 This is a cross-sectional schematic diagram of the electrode winding 20, which can be applied to batteries such as lithium-ion secondary batteries (methods 5-6). Figure 36 As shown, the electrode winding body 20 of method 5-6 is formed by winding a laminated structure consisting of a positive electrode 21 and a negative electrode 22 separated by a separator. The negative electrode 22 is located at the innermost periphery of the electrode winding body 20. Here, in the innermost periphery of the positive electrode 21, which is opposite to the negative electrode active material layer 22B of the innermost periphery of the negative electrode 22, no positive electrode active material layer 21B is provided. That is, the negative electrode active material layer 22B of the innermost periphery of the negative electrode 22 is opposite to the positive electrode current collector 21A of the positive electrode 21 located on its outer side.

[0407] [Effect]

[0408] According to the positive electrode active material layer 21B of method 5-6, since the positive electrode active material layer 21B is not provided in the innermost peripheral portion of the positive electrode 21 opposite to the negative electrode active material layer 22B in the innermost peripheral portion of the negative electrode 22, the expansion of the innermost peripheral portion of the negative electrode 22 during charging can be suppressed. As a result, it is possible to prevent a part of the positive electrode 21 from being bent into the through hole 26 located in the center of the electrode winding body 20.

[0409] (5-7)

[0410] [structure]

[0411] Figure 37A This is a cross-sectional schematic diagram of the positive electrode 21, which can be applied to batteries such as lithium-ion secondary batteries (method 5-7-1). Figure 37A As shown, the positive electrode 21 of embodiment 5-7-1 includes a positive current collector 21A, a positive active material layer 21B disposed on its surface, and an insulating layer 21Z. In the L direction, the positive current collector 21A and the positive active material layer 21B extend from the winding center side edge 21E1 to the winding outer peripheral side edge 21E2, respectively. That is, in the L direction, the position of the front end T21B1 of the positive active material layer 21B coincides with the position of the front end T21A1 of the positive current collector 21A, and the position of the front end T21B2 of the positive active material layer 21B coincides with the position of the front end T21A2 of the positive current collector 21A. The insulating layer 21Z covers the front end T21B1 and its vicinity of the positive active material layer 21B, as well as the front end T21B2 and its vicinity of the positive active material layer 21B. It should be noted that, as... Figure 37BAs shown in the positive electrode 21 of configuration 5-7-2, the insulating layer 21Z1 can be configured to extend in the L direction around the center edge 21E1, or it can be configured to extend in the L direction around the outer peripheral edge 21E2. Furthermore, a portion of the insulating layer 21Z can be impregnated into the positive electrode active material layer 21B.

[0412] [Effect]

[0413] According to methods 5-7-1 and 5-7-2, the positive electrode 21, due to the presence of the insulating layer 21Z, can protect the leading edges T21B1 and T21B2 of the positive electrode active material layer 21B and their vicinity. By providing the insulating layer 21Z, the shedding of the positive electrode active material from the leading edges T21B1 and T21B2 of the positive electrode active material layer 21B and their vicinity can be suppressed, thereby inhibiting dust generation originating from the positive electrode 21. As a result, a reduction in open-circuit voltage (OCV) failure rate and suppression of short-circuit occurrences during storage can be expected.

[0414] Furthermore, the insulating layer 21Z acts as a buffer material, mitigating the stress on the separator 23 caused by the expansion and contraction of the electrode winding 20 during charge-discharge cycles. In addition, the insulating layer 21Z, as a buffer material, reduces friction between the positive electrode 21 and the separator 23 caused by the expansion and contraction of the electrode winding 20 during charge-discharge cycles, preventing the positive electrode active material from detaching from the positive electrode active material layer 21B and avoiding unintended exposure of the positive electrode current collector 21A. As a result, the insulating layer 21Z serves as both a buffer and an insulating material, effectively suppressing short circuits during charge-discharge cycles.

[0415] (5-8)

[0416] [structure]

[0417] Figure 38A This is a cross-sectional schematic diagram showing the electrode winding body 20 of method 5-8, which can be applied to batteries such as lithium-ion secondary batteries. The electrode winding body 20 of method 5-8 is formed by winding a laminated structure consisting of a positive electrode 21 and a negative electrode 22 separated by a separator. Figure 38A As shown, in the innermost peripheral portion of the positive electrode 21 of the electrode winding body 20 of methods 5-8, a positive current collector 21A that is not covered by the positive electrode active material layer 21B is wound around at least one turn. Additionally, Figure 38B This is a top view of the positive electrode 21 in the electrode winding body 20 of method 5-8 after it has been unfolded. Figure 38BAs shown, the positive electrode 21 has an exposed portion of the positive current collector 21A near its upper edge in the W direction, which is not covered by the positive active material layer 21B. In the positive electrode 21, the insulating layer 21D is configured to span the boundary KW between the exposed portion of the positive current collector 21A in the W direction and the portion covered by the positive active material layer 21B. Additionally, the positive electrode 21 has an exposed portion of the positive current collector 21A near its winding center side edge 21E1 in the L direction, which is not covered by the positive active material layer 21B. In the positive electrode 21, the insulating layer 21F is configured to span the boundary KL between the exposed portion of the positive current collector 21A in the L direction and the portion covered by the positive active material layer 21B. Here, in the W direction, the position of the front end T21F of the insulating layer 21F is located between the position of the front end T21A of the positive current collector 21A and the position of the front end T21B of the positive active material layer 21B. Furthermore, in the W direction, the insulating layer 21D is positioned inward and backward from the position of the front end T21A of the positive current collector 21A. That is, both the insulating layers 21F and 21D are positioned in the W direction away from the front end T21A of the positive current collector 21A. It should be noted that the area near the outer peripheral edge 21E2 of the positive electrode 21 in the L direction may also have the same structure as the area near the center edge 21E1 of the positive electrode 21 in the L direction described above. It should be noted that the insulating layers 21F and 21D may be, for example, layers formed by attaching a strip made of insulating material to the positive current collector 21A and the positive active material layer 21B, or coating layers formed by applying insulating material in a manner that covers the boundary KW and its vicinity and the boundary KL and its vicinity, respectively.

[0418] [Effect]

[0419] According to the positive electrode 21 of methods 5-8, in the innermost circumferential portion of the electrode winding body 20, only the positive current collector 21A is wound more than once in the positive electrode 21, so the inner diameter of the portion in the electrode winding body 20 where the positive active material layer 21B is provided becomes larger. Therefore, for example, the stress applied to the positive active material layer 21B due to the expansion of the negative electrode 22 during charge-discharge cycles is mitigated. As a result, damage such as cracking of the positive active material layer 21B can be avoided. In addition, buckling in the innermost circumferential portion of the positive electrode 21 can be suppressed, and internal short circuits can be avoided. Furthermore, since both the insulating layer 21F and the insulating layer 21D are provided at positions away from the front end T21A of the positive current collector 21A in the W direction, the positive current collector 21A and the positive current collector plate can be electrically and well bonded.

[0420] (5-9)

[0421] [structure]

[0422] Figure 39 This is a cross-sectional schematic diagram of the electrode winding body 20 of methods 5-9, which can be applied to batteries such as lithium-ion secondary batteries. In the innermost peripheral portion of the positive electrode 21, the electrode winding body 20 of method 5-9 covers the area from the starting end of the winding to 3.6 mm on the outer surface of the positive electrode current collector 21A by the insulating layer 21D. It should be noted that the insulating layer 21F and the insulating layer 21D can be, for example, layers formed by attaching a strip made of insulating material to the positive electrode current collector 21A and the positive electrode active material layer 21B, or coating layers formed by coating insulating material in a manner that covers the boundary KW and its vicinity and the boundary KL and its vicinity, respectively.

[0423] [Effect]

[0424] According to the positive electrode 21 of methods 5-9, for example, when the electrode winding body 20 is manufactured by winding a laminated structure including the positive electrode 21 and the negative electrode 22, even if cracks appear on the positive electrode active material layer 21B, the shedding of the positive electrode active material layer 21B can be suppressed by the insulating layer 21D. As a result, a positive electrode active material layer 21B with high in-plane density can be achieved.

[0425] (6-1)

[0426] [structure]

[0427] Figure 40A This is a schematic diagram illustrating the negative electrode active material particles 22BP and porous CMC (carboxymethyl cellulose) contained in the negative electrode active material layer 22B of method 6-1, which can be applied to batteries such as lithium-ion secondary batteries. The porous CMC is a binder present in the gaps between the multiple negative electrode active material particles 22BP. The porous CMC is, for example, a material that is made porous by adding NMP (N-methyl-2-pyrrolidone), which is a poor solvent, to foam it.

[0428] [Effect]

[0429] According to the negative electrode active material layer 22B of method 6-1, lithium ion channels are formed by making the CMC porous. Therefore, lithium ions can easily pass through the CMC. Therefore, even when the negative electrode active material layer 22B is thickened, the ion resistance of the electrode winding 20 can be reduced, and further high output can be expected.

[0430] (6-2)

[0431] [structure]

[0432] Figure 40BThis is a magnified microscopic photograph showing the negative electrode active material particles 22BP and the porous CMC (carboxymethyl cellulose) contained in the negative electrode active material layer 22B of method 6-2, which can be applied to batteries such as lithium-ion secondary batteries. The porous CMC is a binder covering at least a portion of the surface of the negative electrode active material particles 22BP. The porous CMC is, for example, a material that is made porous by adding NMP (N-methyl-2-pyrrolidone) as a poor solvent to foam it.

[0433] [Effect]

[0434] According to the negative electrode active material layer 22B of method 6-2, since the surface of the negative electrode active material particles 22BP is covered by porous CMC, lithium ions can more easily permeate through the CMC and reach the negative electrode active material particles 22BP compared to the case where the surface of the negative electrode active material particles 22BP is covered by non-porous solid CMC. Therefore, even when the negative electrode active material layer 22B is thickened, the ion resistance of the electrode winding 20 can be reduced, and further high output can be expected.

[0435] (6-3)

[0436] [structure]

[0437] Figure 40C This is a cross-sectional schematic diagram of the negative electrode 22, which can be applied to batteries such as lithium-ion secondary batteries (method 6-3). Figure 40C As shown, the negative electrode 22 of embodiment 6-3 includes a negative electrode current collector 22A, a negative electrode active material layer 22B disposed on its surface, and a masking layer 22D. In the W direction, the position of the front end T22B of the negative electrode active material layer 22B is recessed inwards compared to the position of the front end T22A of the negative electrode current collector 22A. Therefore, a portion of the negative electrode current collector 22A is exposed and not covered by the negative electrode active material layer 22B. The masking layer 22D covers the exposed portion of the negative electrode current collector 22A and the vicinity of the front end T22B of the negative electrode active material layer 22B.

[0438] [Effect]

[0439] According to the negative electrode 22 of method 6-3, the presence of the masking layer 22D protects the vicinity of the front end T22B of the negative electrode active material layer 22B. By providing the masking layer 22D, the shedding of the negative electrode active material near the front end T22B of the negative electrode active material layer 22B can be suppressed, and the generation of dust originating from the negative electrode 22 can be inhibited. As a result, a reduction in open-circuit voltage (OCV) failure rate and suppression of short circuits during storage can be expected.

[0440] Furthermore, the masking layer 22D acts as a buffer material, mitigating the stress on the diaphragm 23 caused by the expansion and contraction of the electrode winding 20 during charge-discharge cycles. In addition, the masking layer 22D, as a buffer material, reduces friction between the negative electrode 22 and the diaphragm 23 caused by the expansion and contraction of the electrode winding 20 during charge-discharge cycles, preventing the negative electrode active material from detaching from the negative electrode active material layer 22B, and avoiding unintended exposure of the negative electrode current collector 22A. As a result, the masking layer 22D serves as both a buffer and an insulating material, effectively suppressing short circuits during charge-discharge cycles.

[0441] (7-1)

[0442] [structure]

[0443] Figure 41 This is a cross-sectional schematic diagram of the electrode winding 20, which can be applied to batteries such as lithium-ion secondary batteries (method 7-1). Figure 41 As shown, the electrode winding body 20 of method 7-1 is formed by winding a laminated body consisting of a positive electrode 21, a separator 23, a negative electrode 22, and a separator 23 stacked sequentially. In the electrode winding body 20 of method 7-1, the separator 23 is absent in the outermost peripheral portion, while the negative electrode 22 is present. More specifically, the outermost peripheral surface of the electrode winding body 20 of method 7-1 becomes the outer surface of the wound negative electrode current collector 22A, such as a copper foil.

[0444] [Effect]

[0445] According to the electrode winding body 20 of method 7-1, since the negative electrode current collector 22A is exposed on its outermost peripheral surface, heat dissipation is improved, and the heat accompanying the battery reaction can be effectively dissipated to the outside. In addition, since the length of the separator 23 of the electrode winding body 20 can be reduced, the capacity of the battery having the electrode winding body 20 can be increased.

[0446] (7-2)

[0447] [structure]

[0448] The electrode winding of method 7-2, which can be applied to batteries such as lithium-ion secondary batteries, is formed by winding a laminate consisting of a positive electrode, a separator, and a negative electrode, stacked sequentially. In the electrode winding of method 7-2, there is no separator at the outermost periphery, but only a negative electrode. More specifically, the outermost periphery of the electrode winding of method 7-2 becomes the outer surface of the wound negative electrode current collector, such as a copper foil. Furthermore, in the electrode winding of method 7-2, there is also no separator at the innermost periphery, but only a negative electrode.

[0449] [Effect]

[0450] According to the electrode winding of method 7-2, since the negative electrode current collector is exposed on its outermost and innermost peripheral surfaces, heat dissipation is improved, and the heat accompanying the battery reaction can be effectively dissipated to the outside. In addition, since the length of the separator of the electrode winding can be reduced, the capacity of the battery equipped with the electrode winding can be increased.

[0451] (7-3)

[0452] [structure]

[0453] The electrode winding body of method 7-3, which can be applied to batteries such as lithium-ion secondary batteries, is formed by winding a laminated body consisting of a positive electrode, a separator, a negative electrode, and a separator, stacked sequentially. Furthermore, in the electrode winding body of method 7-3, only the separator exists in the central portion of the winding, among the positive electrode, separator, and negative electrode. In the central portion of the winding, only the separator of the positive electrode and negative electrode is wound multiple times.

[0454] [Effect]

[0455] According to the electrode winding body of method 7-3, since only the positive electrode, the separator, and the separator of the negative electrode are wound multiple times in the winding center portion, it can resist stress even when stress is applied to the positive electrode active material layer, for example, due to the expansion of the negative electrode during charging. Therefore, it is possible to prevent cracks or buckling from occurring on the positive electrode active material layer.

[0456] (7-4)

[0457] [structure]

[0458] Figure 42 This is a cross-sectional schematic diagram of the electrode winding 20, which can be applied to batteries such as lithium-ion secondary batteries (method 7-4). Figure 42 As shown, the electrode winding body 20 of method 7-4 is formed by winding a laminate consisting of a positive electrode, a separator, a negative electrode, and a separator stacked sequentially. In the electrode winding body 20 of method 7-4, a sheet-like insulating member Z is provided on at least one of a portion of the surface of the positive electrode and a portion of the surface of the negative electrode. The insulating member Z has a predetermined length in the winding direction. The insulating member Z may also be provided at multiple locations in the winding direction.

[0459] [Effect]

[0460] According to the electrode winding 20 of method 7-4, due to the provision of the insulating member Z, a height difference equivalent to the thickness of the insulating member Z is generated on at least one of the surfaces of the positive electrode and the negative electrode. Therefore, even if the negative electrode expands during charging, multiple stress concentration points will not be generated inside the electrode winding 20, thereby eliminating areas of high local stress concentration. As a result, cracking and detachment of the positive electrode active material layer, or cracking and breakage in the separator, can be avoided, improving safety.

[0461] (7-6)

[0462] [structure]

[0463] Figure 43A This is a magnified cross-sectional view of the upper end of the electrode winding body 20 in the height direction Z of the structure 7-6, which can be applied to batteries such as lithium-ion secondary batteries. Figure 43B This is an enlarged cross-sectional view of the lower end of the electrode winding 20 in the height direction Z of method 7-6. For example... Figure 43A As shown, the upper end of the electrode winding 20 has a positive current collector compression section 21CS. The positive current collector compression section 21CS is a portion of the positive current collector (e.g., aluminum foil) constituting the electrode winding 20, located radially within the electrode winding. Figure 43A The portion of the paper (in the horizontal direction) where adjacent upper edges are flattened so that they overlap in the height direction Z without sandwiching a diaphragm. The upper surface of the positive current collector compression portion 21CS is, for example, joined to the positive current collector plate. On the other hand, as Figure 43B As shown, the lower end of the electrode winding 20 has a negative current collector compression section 22CS. The negative current collector compression section 22CS is a portion of the negative current collector (e.g., copper foil) constituting the electrode winding 20, located radially within the electrode winding. Figure 43B The portion of the negative current collector compression section 22CS that is flattened so that it overlaps with each other in the height direction Z without sandwiching a diaphragm. The lower surface of the negative current collector compression section 22CS is, for example, joined to the negative current collector plate. Here, the maximum value of the thickness (dimension in the height direction Z) H21CS of the positive current collector compression section 21CS is greater than the maximum value of the thickness (dimension in the height direction Z) H22CS of the negative current collector compression section 22CS.

[0464] [Effect]

[0465] According to the electrode winding body 20 of method 7-6, the maximum value of the thickness H21CS of the positive current collector compression section 21CS is greater than the maximum value of the thickness H22CS of the negative current collector compression section 22CS. Therefore, the connection resistance between the positive current collector compression section 21CS and the positive current collector plate, and the connection resistance between the negative current collector compression section 22CS and the negative current collector can be reduced in a balanced manner.

[0466] (8-1)

[0467] The negative electrode current collector in method 8-1 is made of high-purity copper foil. Specifically, it is made of copper foil with a purity of 99.99% or higher. With such copper foil, a current collector of 0.1677 μΩ can be obtained. Volume resistivity below [m], 400 [W / m] A thermal conductivity of [k] or higher. By using such copper foil as the negative electrode current collector, heat generation during high input / output cycles can be suppressed, the temperature rise of the secondary battery can be controlled, and good cycle characteristics can be obtained. Furthermore, for example, the improved thermal conductivity of the negative electrode current collector and the negative electrode current collector plate allows heat generated in the electrode winding to be effectively released to the outside via the negative electrode current collector plate and the outer packaging can. As a result, good cycle characteristics can be obtained. In addition, since it is a high-purity copper foil, its excellent ductility also helps to suppress cracking of the negative electrode current collector that occurs during the expansion and contraction of the charging and discharging process.

[0468] (8-2)

[0469] [structure]

[0470] Figure 44 This is a cross-sectional schematic diagram showing the area near the upper end face 41 of the electrode winding body 20 in the secondary battery of method 8-2. The upper edge of the positive current collector forming the upper end face 41 of the electrode winding body 20 is welded to the positive current collector plate 24. Here, the gap G1, which is the offset in the radial direction between the outer edge of the electrode winding body 20 and the outer edge of the positive current collector plate 24, is less than 1 mm. In addition, the gap G2, which is the offset in the radial direction between the inner edge of the through hole 26 in the electrode winding body 20 and the inner edge of the opening 35 of the positive current collector plate 24, is less than 0.5 mm. That is, most of the area of ​​the upper end face 41 of the electrode winding body 20 is joined to the positive current collector plate 24. Similarly, in the secondary battery of method 8-2, most of the area of ​​the lower end face 42 of the electrode winding body 20 may also be joined to the negative current collector plate 25.

[0471] [Effect]

[0472] Based on the secondary battery of method 8-2, improvements in high-load discharge characteristics, suppression of short circuits during charge-discharge cycles, and suppression of short circuits during high-temperature storage can be expected.

[0473] (8-3-1)

[0474] [structure]

[0475] Figure 45AThis is a cross-sectional schematic diagram showing the area near the upper end face 41 of the electrode winding body 20 in the secondary battery of configuration 8-3-1. In the secondary battery of configuration 8-3-1, the electrode winding body 20 has a first region 20-1, a second region 20-2, and a third region 20-3 sequentially along the height direction Z of the secondary battery. The first region 20-1 is a region formed by stacking and winding the positive and negative electrodes with a separator in between. The second region 20-2 is a region in the wound positive electrode where multiple upper portions of the positive current collector not covered by the positive active material layer are arranged separately along the radial direction R of the secondary battery without overlapping each other. The third region 20-3 is a region in the wound positive electrode where multiple upper portions of the positive current collector not covered by the positive active material layer are compressed and flattened in an overlapping manner. The upper surface of the third region 20-3 becomes the upper end face 41 of the electrode winding body 20, and the upper end face 41 is joined to the positive current collector plate 24 by welding or the like. In the secondary battery of method 8-3-1, the inner diameter D35 of the opening 35 of the positive electrode current collector 24 is smaller than the inner diameter D26 of the through hole 26 of the electrode winding 20. Therefore, a portion of the positive electrode current collector 24 extends into the through hole 26. It should be noted that in the secondary battery of method 8-3-1, the outer diameter of the electrode winding 20 is substantially the same as the outer diameter of the positive electrode current collector 24.

[0476] [Effect]

[0477] According to the secondary battery of method 8-3-1, the inner diameter D35 of the opening 35 of the positive electrode current collector 24 is smaller than the inner diameter D26 of the through hole 26 of the electrode winding 20, and almost the entire area of ​​the upper end face 41 of the electrode winding 20 is engaged with the positive electrode current collector 24. Therefore, improved high-load discharge characteristics, suppression of short circuits during charge-discharge cycles, and suppression of short circuits during high-temperature storage can be expected. It should be noted that in the secondary battery of method 8-3-1, the inner diameter of the opening 36 of the negative electrode current collector 25 can also be made smaller than the inner diameter D26 of the through hole 26 of the electrode winding 20, and most of the lower end face 42 of the electrode winding 20 is engaged with the negative electrode current collector 25.

[0478] (8-3-2)

[0479] [structure]

[0480] Figure 45BThis is a cross-sectional schematic diagram showing the area near the upper end face 41 of the electrode winding body 20 in the secondary battery of configuration 8-3-2. In the secondary battery of configuration 8-3-2, the electrode winding body 20 has a first region 20-1, a second region 20-2, and a third region 20-3 sequentially along the height direction Z of the secondary battery. The first region 20-1 is a region formed by stacking and winding the positive and negative electrodes with a separator in between. The second region 20-2 is a region in the wound positive electrode where multiple upper portions of the positive current collector not covered by the positive active material layer are arranged separately along the radial direction R of the secondary battery without overlapping each other. The third region 20-3 is a region in the wound positive electrode where multiple upper portions of the positive current collector not covered by the positive active material layer are compressed and flattened in a way that overlaps each other. The upper surface of the third region 20-3 becomes the upper end face 41 of the electrode winding body 20, and the upper end face 41 is joined to the positive current collector plate 24 by welding or the like. In the secondary battery of method 8-3-2, the third region 20-3 has a recess 20U1 at its inner peripheral edge. The recess 20U1 is formed at the inner peripheral edge of the compressed portion of the positive current collector in the third region 20-3, that is, the portion of the positive current collector not covered by the positive active material layer where multiple portions overlap. The recess 20U1 is shaped by bending the inner peripheral edge of the compressed portion of the positive current collector in the third region 20-3 outwards. It should be noted that, except for the portion where the recess 20U1 is provided, the inner diameter D26 of the through hole 26 of the electrode winding 20 is substantially the same as the inner diameter D35 of the opening 35 of the positive current collector plate 24. However, the inner diameter D35 may be smaller than the inner diameter D26. In addition, in the secondary battery of method 8-3-2, the outer diameter of the electrode winding 20 is substantially the same as the outer diameter of the positive current collector plate 24.

[0481] [Effect]

[0482] According to the secondary battery of method 8-3-2, almost the entire area of ​​the upper end face 41 of the electrode winding 20 is engaged with the positive current collector 24. Furthermore, since the third region 20-3 has a recess 20U1, for example, when the negative electrode expands during charging, buckling of the innermost circumferential portion of the electrode winding 20 can be suppressed. Therefore, improvements in high-load discharge characteristics, suppression of short circuits during charge-discharge cycles, and suppression of short circuits during high-temperature storage can be expected. It should be noted that in the secondary battery of method 8-3-2, the negative current collector may also have a portion shaped such that its inner circumferential edge is bent towards the outer circumferential side of its compressed portion.

[0483] (8-3-3)

[0484] [structure]

[0485] Figure 45CThis is a cross-sectional schematic diagram showing the area near the upper end face 41 of the electrode winding body 20 in the secondary battery of configuration 8-3-3. In the secondary battery of configuration 8-3-3, the electrode winding body 20 has a first region 20-1, a second region 20-2, and a third region 20-3 sequentially along the height direction Z of the secondary battery. The first region 20-1 is a region formed by stacking and winding the positive and negative electrodes with a separator in between. The second region 20-2 is a region in the wound positive electrode where multiple upper portions of the positive current collector not covered by the positive active material layer are arranged separately along the radial direction R of the secondary battery without overlapping each other. The third region 20-3 is a region in the wound positive electrode where multiple upper portions of the positive current collector not covered by the positive active material layer are compressed and flattened in a way that overlaps each other. The upper surface of the third region 20-3 becomes the upper end face 41 of the electrode winding body 20, and the upper end face 41 is joined to the positive current collector plate 24 by welding or the like. In the secondary battery of method 8-3-3, the inner diameter D35 of the opening 35 of the positive electrode current collector 24 is smaller than the inner diameter D26 of the through hole 26 of the electrode winding body 20. Therefore, a portion of the positive electrode current collector 24 extends into the through hole 26. Furthermore, a bent portion 24T1 is provided at the periphery of the opening 35 of the positive electrode current collector 24, bending inwards into the through hole 26. The bent portion 24T1 covers at least a portion of the inner peripheral edge of the third region 20-3. It should be noted that in the secondary battery of method 8-3-3, the outer diameter of the electrode winding body 20 is substantially the same as the outer diameter of the positive electrode current collector 24.

[0486] [Effect]

[0487] According to the secondary battery of method 8-3-3, almost the entire area of ​​the upper end face 41 of the electrode winding 20 is joined to the positive electrode current collector 24. Furthermore, the inner peripheral edge of the third region 20-3 is covered by the bent portion 24T1 of the positive electrode current collector 24. Therefore, for example, in the event of expansion of the negative electrode during charging, buckling in the innermost peripheral portion of the electrode winding 20 can be suppressed. Thus, improved high-load discharge characteristics, suppression of short circuits during charge-discharge cycles, and suppression of short circuits during high-temperature storage are expected. It should be noted that in the secondary battery of method 8-3-3, a bent portion may also be provided at the periphery of the opening 36 for the negative electrode current collector 25, such that the bent portion of the negative electrode current collector 25 covers at least a portion of the inner peripheral edge near the lower end face 42 of the electrode winding 20.

[0488] (8-3-4)

[0489] [structure]

[0490] Figure 45DThis is a cross-sectional schematic diagram showing the area near the upper end face 41 of the electrode winding body 20 in the secondary battery of configuration 8-3-4. In the secondary battery of configuration 8-3-4, the electrode winding body 20 has a first region 20-1, a second region 20-2, and a third region 20-3 sequentially along the height direction Z of the secondary battery. The first region 20-1 is a region formed by stacking and winding the positive and negative electrodes with a separator in between. The second region 20-2 is a region in the wound positive electrode where multiple upper portions of the positive current collector not covered by the positive active material layer are arranged separately along the radial direction R of the secondary battery without overlapping each other. The third region 20-3 is a region in the wound positive electrode where multiple upper portions of the positive current collector not covered by the positive active material layer are compressed and flattened in an overlapping manner. The upper surface of the third region 20-3 becomes the upper end face 41 of the electrode winding body 20, and the upper end face 41 is joined to the positive current collector plate 24 by welding or the like. In the secondary battery of configuration 8-3-4, the inner diameter D35 of the opening 35 of the positive electrode current collector 24 is smaller than the inner diameter D26 of the through hole 26 of the electrode winding body 20. Therefore, a portion of the positive electrode current collector 24 extends into the through hole 26. Furthermore, in the secondary battery of configuration 8-3-4, the third region 20-3 has a recess 20U1 at its inner peripheral edge. The recess 20U1 is shaped by bending the inner peripheral edge of the compressed portion of the positive electrode current collector in the third region 20-3 outwards. Additionally, a bent portion 24T1 is provided at the periphery of the opening 35 of the positive electrode current collector 24. The bent portion 24T1 covers at least a portion of the recess 20U1 in the third region 20-3. It should be noted that in the secondary battery of configuration 8-3-4, the outer diameter of the electrode winding body 20 is substantially the same as the outer diameter of the positive electrode current collector 24.

[0491] [Effect]

[0492] According to the secondary battery of method 8-3-4, almost the entire area of ​​the upper end face 41 of the electrode winding 20 is joined to the positive electrode current collector 24. Furthermore, at least a portion of the recess 20U1 provided at the inner peripheral edge of the third region 20-3 is covered by the bent portion 24T1 of the positive electrode current collector 24. Therefore, for example, in the event that the negative electrode expands during charging, buckling in the innermost peripheral portion of the electrode winding 20 can be suppressed. Thus, improvements in high-load discharge characteristics, suppression of short circuits during charge-discharge cycles, and suppression of short circuits during high-temperature storage can be expected. It should be noted that in the secondary battery of method 8-3-4, for the negative electrode current collector 25, a bent portion may be provided at the periphery of the opening 36, and a recess may be provided at the inner peripheral edge near the lower end face 42 of the electrode winding 20, with the bent portion of the negative electrode current collector 25 covering the recess of the electrode winding 20.

[0493] (8-4-1)

[0494] [structure]

[0495] Figure 46A This is a cross-sectional schematic diagram showing the area near the upper end face 41 of the electrode winding body 20 in the secondary battery of method 8-4-1. In the secondary battery of method 8-4-1, the electrode winding body 20 has a first region 20-1, a second region 20-2, and a third region 20-3 sequentially along the height direction Z of the secondary battery. The first region 20-1 is a region formed by stacking and winding the positive and negative electrodes with a separator in between. The second region 20-2 is a region in the wound positive electrode where multiple upper portions of the positive current collector not covered by the positive electrode active material layer are not overlapping and are arranged separately along the radial direction R of the secondary battery. The third region 20-3 is a region in the wound positive electrode where multiple upper portions of the positive current collector not covered by the positive electrode active material layer are compressed and flattened in an overlapping manner. The upper surface of the third region 20-3 becomes the upper end face 41 of the electrode winding body 20, and the upper end face 41 is joined to the positive current collector plate 24 by welding or the like. In the secondary battery of method 8-4-1, the third region 20-3 has a recess 20U2 at its outer peripheral end edge. The recess 20U2 is shaped by bending the outer peripheral end edge of the compressed portion of the positive current collector in the third region 20-3 inward to the inner peripheral side. It should be noted that the inner diameter D26 of the through hole 26 of the electrode winding 20 is substantially the same as the inner diameter D35 of the opening 35 of the positive current collector plate 24. However, the inner diameter D35 may be smaller than the inner diameter D26.

[0496] [Effect]

[0497] According to the secondary battery of method 8-4-1, almost the entire area of ​​the upper end face 41 of the electrode winding 20 is engaged with the positive current collector 24. Furthermore, since the third region 20-3 has a recess 20U2, even if the negative electrode expands during charging, it is difficult for the position of the outermost peripheral portion of the electrode winding 20 to shift from the position of the outermost peripheral portion of the positive current collector 24. Therefore, the current collection efficiency is improved. Additionally, improvements in high-load discharge characteristics, suppression of short circuits during charge-discharge cycles, and suppression of short circuits during high-temperature storage are expected. It should be noted that in the secondary battery of method 8-4-1, the negative current collector may also have a portion shaped such that its compressed portion is bent outwards towards the outer periphery.

[0498] (8-4-2)

[0499] [structure]

[0500] Figure 46BThis is a cross-sectional schematic diagram showing the area near the upper end face 41 of the electrode winding body 20 in the secondary battery of method 8-4-2. In the secondary battery of method 8-4-2, the electrode winding body 20 has a first region 20-1, a second region 20-2, and a third region 20-3 sequentially along the height direction Z of the secondary battery. The first region 20-1 is a region formed by stacking and winding the positive and negative electrodes with a separator in between. The second region 20-2 is a region in the wound positive electrode where multiple upper portions of the positive current collector not covered by the positive electrode active material layer are not overlapping and are arranged separately along the radial direction R of the secondary battery. The third region 20-3 is a region in the wound positive electrode where multiple upper portions of the positive current collector not covered by the positive electrode active material layer are compressed and flattened in an overlapping manner. The upper surface of the third region 20-3 becomes the upper end face 41 of the electrode winding body 20, and the upper end face 41 is joined to the positive current collector plate 24 by welding or the like. In the secondary battery of method 8-4-2, the outer diameter of the positive current collector 24 is larger than the outer diameter of the electrode winding 20. Therefore, a portion of the positive current collector 24 extends outward beyond the third region 20-3 of the electrode winding 20. Furthermore, a bent portion 24T2 is provided at the outer periphery of the positive current collector 24, bending towards the negative current collector 25. The bent portion 24T2 covers at least a portion of the outer peripheral edge of the third region 20-3. It should be noted that in the secondary battery of method 8-4-2, the inner diameter D26 of the through hole 26 of the electrode winding 20 is substantially the same as the inner diameter D35 of the opening 35 of the positive current collector 24.

[0501] [Effect]

[0502] According to the secondary battery of method 8-4-2, almost the entire area of ​​the upper end face 41 of the electrode winding 20 is joined to the positive current collector 24. Furthermore, the outer peripheral edge of the third region 20-3 is covered by the bent portion 24T of the positive current collector 24. Therefore, even if the negative electrode expands during charging, it is difficult for the position of the outermost peripheral portion of the electrode winding 20 to shift from the position of the outermost peripheral portion of the positive current collector 24. Thus, the current collection efficiency is improved. Additionally, improvements in high-load discharge characteristics, suppression of short circuits during charge-discharge cycles, and suppression of short circuits during high-temperature storage are expected. It should be noted that in the secondary battery of method 8-4-2, a bent portion may also be provided at the outer peripheral edge of the negative current collector 25, and the bent portion of the negative current collector 25 may cover at least a portion of the outer peripheral edge near the lower end face 42 of the electrode winding 20.

[0503] (8-4-3)

[0504] [structure]

[0505] Figure 46CThis is a cross-sectional schematic diagram showing the area near the upper end face 41 of the electrode winding body 20 in the secondary battery of configuration 8-4-3. In the secondary battery of configuration 8-4-3, the electrode winding body 20 has a first region 20-1, a second region 20-2, and a third region 20-3 sequentially along the height direction Z of the secondary battery. The first region 20-1 is a region formed by stacking and winding the positive and negative electrodes with a separator in between. The second region 20-2 is a region in the wound positive electrode where multiple upper portions of the positive current collector not covered by the positive active material layer are not overlapping and are arranged separately along the radial direction R of the secondary battery. The third region 20-3 is a region in the wound positive electrode where multiple upper portions of the positive current collector not covered by the positive active material layer are compressed and flattened in an overlapping manner. The upper surface of the third region 20-3 becomes the upper end face 41 of the electrode winding body 20, and the upper end face 41 is joined to the positive current collector plate 24 by welding or the like. In the secondary battery of method 8-4-2, the outer diameter of the positive current collector 24 is larger than the outer diameter of the electrode winding 20. Therefore, a portion of the positive current collector 24 extends to a position further outward than the third region 20-3 of the electrode winding 20. Furthermore, in the secondary battery of method 8-4-3, the third region 20-3 has a recess 20U2 at its outer peripheral edge. The recess 20U2 is shaped by bending the outer peripheral edge of the compressed portion of the positive current collector in the third region 20-3 inward. Additionally, a bent portion 24T2 is provided at the outer peripheral edge of the positive current collector 24. The bent portion 24T2 covers at least a portion of the recess 20U2 in the third region 20-3. It should be noted that in the secondary battery of method 8-4-3, the inner diameter D26 of the through hole 26 of the electrode winding body 20 is substantially the same as the inner diameter D35 of the opening 35 of the positive electrode current collector plate 24.

[0506] [Effect]

[0507] According to the secondary battery of method 8-4-3, almost the entire area of ​​the upper end face 41 of the electrode winding 20 is joined to the positive current collector 24. Furthermore, at least a portion of the recess 20U2 provided at the outer peripheral edge of the third region 20-3 is covered by the bent portion 24T2 of the positive current collector 24. Therefore, even if the negative electrode expands during charging, it is difficult for the position of the outermost peripheral portion of the electrode winding 20 to shift from the position of the outermost peripheral portion of the positive current collector 24. Thus, the current collection efficiency is improved. Additionally, improvements in high-load discharge characteristics, suppression of short circuits during charge-discharge cycles, and suppression of short circuits during high-temperature storage are expected. It should be noted that in the secondary battery of method 8-4-3, for the negative current collector 25, a bent portion may be provided at the outer peripheral edge, and a recess may be provided at the outer peripheral edge near the lower end face 42 of the electrode winding 20, with the bent portion of the negative current collector 25 covering the recess of the electrode winding 20.

[0508] (8-5-1)

[0509] [structure]

[0510] Figure 47A This is a cross-sectional schematic diagram showing the area near the upper end face 41 of the electrode winding 20 in the secondary battery of configuration 8-5-1. In the secondary battery of configuration 8-5-1, the outer diameter of the positive electrode current collector 24 is larger than the outer diameter of the electrode winding 20. Therefore, a portion of the positive electrode current collector 24 extends outward beyond the third region 20-3 of the electrode winding 20. Furthermore, a bent portion 24T2 is provided at the outer peripheral edge of the positive electrode current collector 24. The bent portion 24T2 covers at least a portion of the outer peripheral edge of the third region 20-3. Additionally, in the secondary battery of configuration 8-5-1, the inner diameter D35 of the opening 35 of the positive electrode current collector 24 is smaller than the inner diameter D26 of the through hole 26 of the electrode winding 20. Therefore, a portion of the positive electrode current collector 24 extends into the through hole 26. Furthermore, a bent portion 24T1 is provided at the periphery of the opening 35 of the positive current collector plate 24, bending inward toward the through hole 26. The bent portion 24T1 covers at least a portion of the inner peripheral edge of the third region 20-3.

[0511] [Effect]

[0512] According to the secondary battery of method 8-5-1, almost the entire area of ​​the upper end face 41 of the electrode winding 20 is joined to the positive current collector 24. Furthermore, the outer peripheral edge of the third region 20-3 is covered by the bend 24T2 of the positive current collector 24. Therefore, even if the negative electrode expands during charging, it is difficult for the position of the outermost peripheral portion of the electrode winding 20 to shift from the position of the outermost peripheral portion of the positive current collector 24. Therefore, current collection efficiency is improved. Additionally, improvements in high-load discharge characteristics, suppression of short circuits during charge-discharge cycles, and suppression of short circuits during high-temperature storage are expected. Furthermore, the inner peripheral edge of the third region 20-3 is covered by the bend 24T1 of the positive current collector 24. Therefore, even if the negative electrode expands during charging, buckling in the innermost peripheral portion of the electrode winding 20 can be suppressed. Therefore, improvements in high-load discharge characteristics, suppression of short circuits during charge-discharge cycles, and suppression of short circuits during high-temperature storage are expected. It should be noted that in the secondary battery of method 8-5-1, a bent portion may be provided on the outer periphery of the negative electrode current collector 25, and the bent portion of the negative electrode current collector 25 may cover at least a portion of the outer peripheral edge near the lower end face 42 of the electrode winding body 20. Alternatively, a bent portion may be provided on the periphery of the opening 36, such that the bent portion of the negative electrode current collector 25 covers at least a portion of the inner peripheral edge near the lower end face 42 of the electrode winding body 20.

[0513] (8-5-2)

[0514] [structure]

[0515] Figure 47BThis is a cross-sectional schematic diagram showing the area near the upper end face 41 of the electrode winding 20 in the secondary battery of configuration 8-5-2. In the secondary battery of configuration 8-5-2, the outer diameter of the positive electrode current collector 24 is larger than the outer diameter of the electrode winding 20. Therefore, a portion of the positive electrode current collector 24 extends to a position further outward than the third region 20-3 of the electrode winding 20. Furthermore, in the secondary battery of configuration 8-5-2, the third region 20-3 has a recess 20U2 at its outer peripheral edge. The recess 20U2 is shaped such that the outer peripheral edge of the compressed portion of the positive electrode current collector in the third region 20-3 is bent inward. Additionally, a bent portion 24T2 is provided at the outer peripheral edge of the positive electrode current collector 24. The bent portion 24T2 covers at least a portion of the recess 20U2 in the third region 20-3. Furthermore, in the secondary battery of method 8-5-2, the inner diameter D35 of the opening 35 of the positive electrode current collector 24 is smaller than the inner diameter D26 of the through hole 26 of the electrode winding body 20. Therefore, a portion of the positive electrode current collector 24 extends into the through hole 26. Additionally, in the secondary battery of method 8-5-2, the third region 20-3 has a recess 20U1 at its inner peripheral edge. The recess 20U1 is shaped by bending the inner peripheral edge of the compressed portion of the positive electrode current collector in the third region 20-3 towards the outer peripheral side. Furthermore, a bent portion 24T1 is provided at the periphery of the opening 35 of the positive electrode current collector 24. The bent portion 24T1 covers at least a portion of the recess 20U1 in the third region 20-3.

[0516] [Effect]

[0517] According to the secondary battery of method 8-5-2, almost the entire area of ​​the upper end face 41 of the electrode winding 20 is joined to the positive current collector 24. Furthermore, at least a portion of the recess 20U2 provided at the outer peripheral edge of the third region 20-3 is covered by the bent portion 24T2 of the positive current collector 24. Therefore, even if the negative electrode expands during charging, it is difficult for the position of the outermost peripheral portion of the electrode winding 20 to shift from the position of the outermost peripheral portion of the positive current collector 24. Therefore, current collection efficiency is improved. Additionally, improvements in high-load discharge characteristics, suppression of short circuits during charge-discharge cycles, and suppression of short circuits during high-temperature storage are expected. Furthermore, according to the secondary battery of method 8-5-2, at least a portion of the recess 20U1 provided at the inner peripheral edge of the third region 20-3 is covered by the bent portion 24T1 of the positive current collector 24. Therefore, even if the negative electrode expands during charging, buckling in the innermost peripheral portion of the electrode winding 20 can be suppressed. Therefore, improvements in high-load discharge characteristics, suppression of short circuits during charge-discharge cycles, and suppression of short circuits during high-temperature storage can be expected. It should be noted that in the secondary battery of method 8-5-2, a bent portion can be provided at the outer periphery of the negative electrode current collector 25, and a recess can be provided at the outer periphery of the lower end face 42 of the electrode winding body 20, with the bent portion of the negative electrode current collector 25 covering the recess of the electrode winding body 20. Furthermore, in the secondary battery of method 8-5-2, a bent portion can be provided at the periphery of the opening 36 of the negative electrode current collector 25, and a recess can be provided at the inner periphery of the lower end face 42 of the electrode winding body 20, with the bent portion of the negative electrode current collector 25 covering the recess of the electrode winding body 20.

[0518] (8-6)

[0519] [structure]

[0520] Figure 48 This is a planar schematic diagram of the electrode winding body 20 and the positive electrode current collector 24 in a secondary battery representing method 8-6. (See diagram below.) Figure 48 As shown, in the secondary battery of methods 8-6, the fan-shaped portion 31 of the electrode winding body 20 and the positive electrode current collector plate 24 are joined at multiple joining points WZ1 to WZ7 by welding or the like. The joining points WZ2 to WZ7 extend radially along the secondary battery with respect to the opening 35 located in the center of the fan-shaped portion 31. Furthermore, the joining point WZ1 is located near the boundary of the fan-shaped portion 31 with the strip-shaped portion 32. The strip-shaped portion 32 is the part that joins with the external terminal. The length of the joining point WZ1 can, for example, be greater than or equal to the width of the strip-shaped portion 32.

[0521] [Effect]

[0522] According to the secondary battery of method 8-6, in addition to the joint portions WZ2 to WZ7, the electrode winding body 20 and the positive current collector plate 24 are also joined at the joint portion WZ1. Therefore, compared to the case where the electrode winding body 20 is joined to the positive current collector plate 24 only at the joint portions WZ2 to WZ7, the resistance between the electrode winding body 20 and the positive current collector plate 24 can be reduced. This is because the length of the conduction path between the joint portion WZ1 and the strip portion 32 is shorter than the length of the conduction path between each of the joint portions WZ2 to WZ7 and the strip portion 32. Therefore, the internal resistance of the secondary battery of method 8-6 decreases, and heat generation can be reduced. Furthermore, even when the electrode winding body 20 expands and contracts due to charging and discharging, stress is applied to the boundary portion between the fan-shaped portion 31 and the strip portion 32. Since the fan-shaped portion 31 and the electrode winding body 20 are joined at the joint portion WZ1, a portion of the fan-shaped portion 31 is also difficult to peel off from the electrode winding body 20. Therefore, the secondary battery according to method 8-6 has excellent operational reliability because it can maintain the contact area between the fan-shaped portion 31 and the electrode winding body 20.

[0523] (9-1)

[0524] [structure]

[0525] In the secondary battery of method 9-1, a non-aqueous electrolyte is impregnated in the electrode winding body 20. This non-aqueous electrolyte contains DMC (dimethyl carbonate) as the main solvent and LiPF6 as the solute. The content of LiPF6 in the non-aqueous electrolyte is less than 12% by weight of the total non-aqueous electrolyte. In addition, the content of DMC in the non-aqueous electrolyte is more than 50% based on the molar ratio of carbonates contained in the non-aqueous electrolyte.

[0526] [Effect]

[0527] According to the secondary battery of method 9-1, since the electrode winding body 20 is immersed in a non-aqueous electrolyte containing a specified amount of thickening LiPF6 in a low-viscosity solvent with DMC as the main solvent, the phenomenon of isolated small amounts of non-aqueous electrolyte inside the secondary battery can be prevented. Therefore, the dissolution of the metal forming the battery canister can be prevented.

[0528] (9-2)

[0529] [structure]

[0530] In the secondary battery of method 9-2, a non-aqueous electrolyte is impregnated in the electrode winding 20. This non-aqueous electrolyte comprises DMC (dimethyl carbonate) as the main solvent, cyclic carbonates as a secondary solvent, and LiPF6 as a solute. The cyclic carbonates in the non-aqueous electrolyte are EC (ethylene carbonate), PC (propylene carbonate), and FEC (fluoroethylene carbonate). The combined content of EC, PC, and FEC in the non-aqueous electrolyte is 20% by weight or more of the total content of the non-aqueous electrolyte, and the content of FEC is 10% by weight or more of the total content of the non-aqueous electrolyte. Furthermore, the content of DMC in the non-aqueous electrolyte is 50% or more, based on the molar ratio of the carbonates contained in the non-aqueous electrolyte.

[0531] [Effect]

[0532] According to the secondary battery of method 9-2, since the low-viscosity non-aqueous electrolyte of the above composition is impregnated in the electrode winding body 20, the phenomenon of small amounts of non-aqueous electrolyte isolation inside the secondary battery can be prevented. Therefore, the dissolution of the metal forming the battery canister can be prevented.

[0533] (9-3)

[0534] [structure]

[0535] In the secondary battery of method 9-3, a swellable strip that swells by being impregnated with electrolyte is wound around the electrode winding 20. For example, in the process of manufacturing the secondary battery of method 9-3, after the electrode winding 20 with the swellable strip wound is inserted into the outer packaging can 11, electrolyte is injected into the outer packaging can 11 to cause the swellable strip to swell. As a result, the electrode winding 20 and the outer packaging can 11 are sealed together by the swellable strip, thereby reducing the air layer between the electrode winding 20 and the outer packaging can 11.

[0536] [Effect]

[0537] In the secondary battery of method 9-3, the electrode winding 20 is tightly sealed to the outer packaging can 11, reducing the amount of air layer that forms the heat insulation layer. Therefore, heat dissipation is excellent, and the heat generated by the electrode winding 20 during charging is effectively transferred to the outer packaging can 11. As a result, high heat dissipation and improved safety are achieved. It should be noted that, as described above, by inserting the swollen strip wound around the electrode winding 20 into the interior of the outer packaging can 11 and allowing it to swell, the secondary battery of method 9-3 can be manufactured without compromising manufacturability.

[0538] (10-1)

[0539] [structure]

[0540] The electrode winding of method 10-1, which can be applied to batteries such as lithium-ion secondary batteries, is formed by winding a laminate consisting of a positive electrode, a separator, and a negative electrode, which are sequentially stacked. In the electrode winding of method 10-1, there is no separator in the innermost peripheral portion, but there is a negative electrode. More specifically, in the innermost peripheral portion of the electrode winding of method 10-1, there is a negative electrode current collector such as copper foil that has been wound multiple times (e.g., more than three times).

[0541] [Effect]

[0542] According to the electrode winding of method 10-1, since multiple negative current collectors are wound around its innermost circumference, the radius of the innermost circumference of the positive electrode wound on its outer side can be increased. Therefore, cracks can be prevented from appearing on the positive electrode active material layer in the innermost circumference of the positive electrode. Therefore, the areal density and bulk density of the positive electrode can be increased.

[0543] (10-2)

[0544] [structure]

[0545] The electrode winding body of method 10-2, which can be applied to batteries such as lithium-ion secondary batteries, is formed by winding a laminate consisting of a positive electrode, a separator, and a negative electrode stacked sequentially. In the electrode winding body of method 10-2, there is no separator in the innermost peripheral portion, but there is a negative electrode. More specifically, in the innermost peripheral portion of the electrode winding body of method 10-2, there is a negative electrode current collector such as copper foil that has been wound multiple times (e.g., more than 3 times). Here, when the thickness of the negative electrode current collector is set as a [μm] and the number of windings is set as b, a×b can be 24μm or more.

[0546] [Effect]

[0547] According to the electrode winding of method 10-2, since multiple negative current collectors are wound around its innermost circumference, the mechanical strength of the electrode winding can be maintained without using a center pin made of a conductive material such as metal. Since the electrode winding of method 10-2 does not have a center pin made of a conductive material, internal short circuits caused by contact between the center pin and the positive and negative current collectors can be avoided.

[0548] (10-3-1)

[0549] [structure]

[0550] Figure 49A This is a plan view showing the unfolded state of the electrode winding body 20 of method 10-3-1, which can be applied to batteries such as lithium-ion secondary batteries. The electrode winding body of method 10-3-1 is formed by winding a laminated body consisting of a positive electrode 21, a separator, a negative electrode 22, and a separator stacked sequentially. Furthermore, in Figure 49AThe description of the diaphragm is omitted. For example... Figure 49A As shown, the electrode winding body 20 of method 10-3-1 has a portion on the winding start end 20E1 side where only the negative electrode 22 exists and the positive electrode 21 does not exist. Therefore, in the winding center portion of the electrode winding body 20 of method 10-3-1, only the negative electrode 22, which is not opposite to the positive electrode 21, is wound multiple times (for example, more than 3 times). A thin copper plate 22C is attached to the negative electrode active material layer 22B in the portion of the negative electrode 22 that is not opposite to the positive electrode 21. The thickness of the copper plate 22C is, for example, about 40 μm. It is possible that all of the copper plate 22C is bonded to the negative electrode active material layer 22B, or only a portion of the copper plate 22C is bonded to the negative electrode active material layer 22B. In the innermost peripheral portion of the electrode winding body 20 of method 10-3-1, the stack of the negative electrode current collector 22A, the negative electrode active material layer 22B, and the copper plate 22C is wound multiple times (for example, more than 3 times) as a whole.

[0551] [Effect]

[0552] According to the electrode winding body of method 10-3-1, the positive electrode 21, the separator, and the negative electrode 22 are wound multiple times only in the winding center portion, and the negative electrode 22 in the winding center portion has a copper plate 22C. Therefore, for example, even if stress is applied to the innermost peripheral portion of the positive electrode 21 of the electrode winding body 20 during charging due to the expansion of the negative electrode 22, the innermost peripheral portion of the positive electrode 21 can resist the stress. Therefore, buckling in the innermost peripheral portion of the positive electrode 21 can be prevented, and cracks in the positive electrode active material layer 21B in the innermost peripheral portion can be prevented. As a result, short circuits inside the battery can be effectively suppressed.

[0553] (10-3-2)

[0554] [structure]

[0555] Figure 49B This is a plan view showing the unfolded state of the electrode winding body 20 of method 10-3-2, which can be applied to batteries such as lithium-ion secondary batteries. The electrode winding body of method 10-3-2 is formed by winding a laminated body consisting of a positive electrode 21, a separator, a negative electrode 22, and a separator stacked sequentially. Furthermore, in Figure 49B The description of the diaphragm is omitted. For example... Figure 49BAs shown, the electrode winding body 20 of method 10-3-2 has a portion on the winding start end 20E1 side where only the negative electrode 22 exists and the positive electrode 21 does not exist. Therefore, in the winding center portion of the electrode winding body 20 of method 10-3-2, only the negative electrode 22, which is not opposite to the positive electrode 21, is wound multiple times (for example, more than 3 times). A thin copper plate 22C is attached to the negative electrode active material layer 22B in the portion of the negative electrode 22 that is not opposite to the positive electrode 21. The thickness of the copper plate 22C is, for example, about 40 μm. It is possible that all of the copper plate 22C is bonded to the negative electrode active material layer 22B, or only a portion of the copper plate 22C is bonded to the negative electrode active material layer 22B. In addition, a resin strip 22D is provided to cover at least a portion of the copper plate 22C. In the innermost circumferential portion of the electrode winding body 20 of method 10-3-2, the laminate of negative electrode current collector 22A, negative electrode active material layer 22B, copper plate 22C and resin tape 22D is wound in an integral manner multiple times (e.g., more than 3 times).

[0556] [Effect]

[0557] According to the electrode winding body of method 10-3-2, the positive electrode 21, the separator, and the negative electrode 22 are wound multiple times only in the winding center portion, and the negative electrode 22 in the winding center portion has a copper plate 22C. Therefore, for example, even if stress is applied to the innermost peripheral portion of the positive electrode 21 of the electrode winding body 20 during charging due to the expansion of the negative electrode 22, the innermost peripheral portion of the positive electrode 21 can resist the stress. Therefore, buckling in the innermost peripheral portion of the positive electrode 21 can be prevented, and cracks in the positive electrode active material layer 21B in the innermost peripheral portion can be prevented. Furthermore, since the copper plate 22C is covered by the resin tape 22D, the height difference between the negative electrode current collector 22A and the copper plate 22C present at the end edge of the copper plate 22C can be mitigated, and the local stress applied to the positive electrode 21 can be mitigated. As a result, short circuits inside the battery can be effectively suppressed.

[0558] (10-4-1)

[0559] [structure]

[0560] Figure 50A This is a plan view showing the unfolded state of the electrode winding body 20 of method 10-4-1, which can be applied to batteries such as lithium-ion secondary batteries. The electrode winding body of method 10-4-1 is formed by winding a laminated body consisting of a positive electrode 21, a separator, a negative electrode 22, and a separator stacked sequentially. Furthermore, in... Figure 50A The description of the diaphragm is omitted. For example... Figure 50AAs shown, the electrode winding body 20 of method 10-4-1 has a portion on the winding start end 20E1 side where only the negative electrode 22 exists and the positive electrode 21 does not exist. Therefore, in the winding center portion of the electrode winding body 20 of method 10-4-1, only the negative electrode 22, which is not opposite to the positive electrode 21, is wound multiple times (for example, more than 3 times). A thin copper plate 22C is attached to the negative electrode active material layer 22B in the portion of the negative electrode 22 that is not opposite to the positive electrode 21. The thickness of the copper plate 22C is, for example, about 40 μm. It is possible that all of the copper plate 22C is bonded to the negative electrode active material layer 22B, or only a portion of the copper plate 22C is bonded to the negative electrode active material layer 22B. In the innermost peripheral portion of the electrode winding body 20 of method 10-4-1, the stack of the negative electrode current collector 22A, the negative electrode active material layer 22B, and the copper plate 22C is wound multiple times (for example, more than 3 times) as a whole. Furthermore, in the electrode winding body 20 of method 10-4-1, a thin-walled portion 61 is provided on a portion of the positive electrode active material layer 21B at the inner peripheral end of the positive electrode 21. The thin-walled portion 61 is a portion of the positive electrode active material layer 21B that has a thickness thinner than the portions other than the thin-walled portion 61. The thin-walled portion 61 is formed, for example, by laser ablation.

[0561] [Effect]

[0562] According to the electrode winding body of method 10-4-1, the negative electrode 22 of the positive electrode 21, the separator, and the negative electrode 22 is wound multiple times only in the winding center portion, and the negative electrode 22 in the winding center portion has a copper plate 22C. Therefore, for example, even if stress is applied to the innermost peripheral portion of the positive electrode 21 of the electrode winding body 20 during charging due to the expansion of the negative electrode 22, the innermost peripheral portion of the positive electrode 21 can resist the stress. Therefore, buckling in the innermost peripheral portion of the positive electrode 21 can be prevented, and cracks in the positive electrode active material layer 21B in the innermost peripheral portion can be prevented. Furthermore, since the positive electrode active material layer 21B has a thin-walled portion 61, the expansion of the negative electrode 22 near the winding center portion of the electrode winding body 20 during charging can be suppressed. As a result, short circuits inside the battery can be effectively suppressed.

[0563] (10-4-2)

[0564] [structure]

[0565] Figure 50B This is a plan view showing the unfolded state of the electrode winding body 20 of method 10-4-2, which can be applied to batteries such as lithium-ion secondary batteries. The electrode winding body of method 10-4-2 is formed by winding a laminated body consisting of a positive electrode 21, a separator, a negative electrode 22, and a separator stacked sequentially. Furthermore, in Figure 50B The description of the diaphragm is omitted. For example... Figure 50BAs shown, the electrode winding body 20 of method 10-4-2 has a portion on the winding start end 20E1 side where only the negative electrode 22 exists and the positive electrode 21 does not exist. Therefore, in the winding center portion of the electrode winding body 20 of method 10-4-2, only the negative electrode 22, which is not opposite to the positive electrode 21, is wound multiple times (for example, more than 3 times). A thin copper plate 22C is attached to the negative electrode active material layer 22B in the portion of the negative electrode 22 that is not opposite to the positive electrode 21. The thickness of the copper plate 22C is, for example, about 40 μm. It is possible that all of the copper plate 22C is bonded to the negative electrode active material layer 22B, or only a portion of the copper plate 22C is bonded to the negative electrode active material layer 22B. In addition, a resin strip 22D is provided to cover at least a portion of the copper plate 22C. In the innermost peripheral portion of the electrode winding body 20 of method 10-4-2, the laminate of the negative electrode current collector 22A, the negative electrode active material layer 22B, the copper plate 22C, and the resin tape 22D is wound multiple times (e.g., more than three times) as a single unit. Furthermore, in the electrode winding body 20 of method 10-4-2, a thin-walled portion 61 is provided on a portion of the positive electrode active material layer 21B at the inner peripheral end of the positive electrode 21. The thin-walled portion 61 is a portion of the positive electrode active material layer 21B with a thickness thinner than the portions other than the thin-walled portion 61. The thin-walled portion 61 is formed, for example, by laser ablation.

[0566] [Effect]

[0567] According to the electrode winding body of method 10-4-2, the positive electrode 21, the separator, and the negative electrode 22 are wound multiple times only in the winding center portion, and the negative electrode 22 in the winding center portion has a copper plate 22C. Therefore, for example, even if stress is applied to the innermost peripheral portion of the positive electrode 21 of the electrode winding body 20 during charging due to the expansion of the negative electrode 22, the innermost peripheral portion of the positive electrode 21 can resist the stress. Therefore, buckling in the innermost peripheral portion of the positive electrode 21 can be prevented, and cracks in the positive electrode active material layer 21B in the innermost peripheral portion can be prevented. In addition, since the copper plate 22C is covered by the resin tape 22D, the height difference between the negative electrode current collector 22A and the copper plate 22C present at the end edge of the copper plate 22C can be mitigated, and the local stress applied to the positive electrode 21 can be mitigated. Furthermore, since the positive electrode active material layer 21B has a thin-walled portion 61, it is possible to suppress the expansion of the negative electrode 22 near the winding center portion of the electrode winding body 20 during charging. As a result, short circuits inside the battery can be effectively suppressed.

[0568] (10-5)

[0569] [structure]

[0570] The electrode winding, which can be applied to batteries such as lithium-ion secondary batteries, has a through hole in its center, for example... Figure 51The diagram shows a spiral spring-shaped core material CS wound body. Specifically, the electrode winding body of method 10-5 is formed by winding a laminate consisting of a positive electrode, a separator, a negative electrode, and a separator sequentially around the core material CS. The core material CS is formed by winding a plate-shaped elastic component, such as stainless steel.

[0571] [Effect]

[0572] According to the electrode winding of method 10-5, a helical spring-shaped core material CS is inserted into the central through hole. Therefore, the outer diameter of the core material CS can vary in accordance with the inner diameter of the electrode winding, and the inner surface of the electrode winding can be in close contact with the outer surface of the core material CS. Therefore, the core material CS can improve the mechanical strength of the electrode winding and suppress deformation of the electrode winding during expansion and contraction. Therefore, buckling in the innermost circumferential portion of the positive electrode 21 can be prevented, and cracks in the positive electrode active material layer 21B in the innermost circumferential portion can be prevented. As a result, short circuits inside the battery can be effectively suppressed.

[0573] (10-6)

[0574] [structure]

[0575] Figure 52 This is a cross-sectional schematic diagram showing the electrode winding body 20 and the center pin CP of method 10-6, which can be applied to batteries such as lithium-ion secondary batteries. The center pin CP is inserted into the through hole 26 at the center of the electrode winding body 20 of method 10-6. The center pin CP includes: a cylindrical core CP-L1, made of a high-rigidity material such as stainless steel; and a resin layer CP-L2 covering the outer peripheral surface of the core CP-L1. The resin layer CP-L2 is made of a resin material that expands upon heating and plastically deforms at a specified temperature (e.g., around 130°C). The resin layer CP-L2 can be, for example, a three-layer structure of PE (polyethylene), polyester, and rubber. The surface of the resin layer CP-L2 is in close contact with the inner surface of the through hole 26 of the electrode winding body 20. In particular, the resin layer CP-L2 can be thermally fused to the inner surface of the through hole 26.

[0576] [Effect]

[0577] According to the electrode winding 20 of method 10-6, a center pin CP is inserted into a through hole 26 at its center, and the surface of the resin layer CP-L2 of the center pin CP is in close contact with the inner surface of the through hole 26. Therefore, the center pin CP improves the mechanical strength of the electrode winding 20 and can suppress the deformation of the electrode winding 20 during expansion and contraction. Therefore, it is possible to prevent buckling or cracking in the innermost peripheral portion of the positive electrode constituting the electrode winding 20, or in the positive electrode active material layer in the innermost peripheral portion. As a result, short circuits inside the battery can be effectively suppressed.

[0578] (10-7)

[0579] [structure]

[0580] Figure 53 This is a cross-sectional schematic diagram of the center pin CP of configuration 10-7, which can be applied to batteries such as lithium-ion secondary batteries. The center pin CP of configuration 10-7 has: a core CP-1 as a cylindrical component; an insulating film CP-2 covering the vicinity of the upper end of the core CP-1; and an insulating film CP-3 covering the vicinity of the lower end of the core CP-1. The core CP-1 is made of a high-rigidity material, such as stainless steel. Examples of structural materials for the insulating films CP-2 and CP-3 include polyester, polyamide, polyolefin, polyacrylate, polymethacrylate, polysulfone, polycarbonate, polypropylene, polyethylene, polysulfone, polytetrafluoroethylene, and polyvinylidene fluoride.

[0581] [Effect]

[0582] According to method 10-7, since the center pin CP covers the vicinity of the upper end and the vicinity of the lower end of the core CP-1 by insulating films CP-2 and CP-3 respectively, the internal short circuit of the battery can be prevented even when vibration is applied or when the center pin CP contacts the top and bottom surfaces of the battery in abnormal situations.

[0583] (13-2)

[0584] [structure]

[0585] Figure 54A This is a perspective view schematically illustrating the appearance of the outer packaging can 11 of embodiment 13-2, which can be applied to batteries such as lithium-ion secondary batteries. The outer packaging can 11 is a container that houses the positive electrode current collector, the negative electrode current collector, and the electrode winding. Ideally, the structural material of the outer packaging can 11 is a material with high thermal conductivity and high rigidity, specifically, a metal material such as iron. The outer packaging can 11 has a bottom 11B and a side wall portion 11W. The outer packaging can 11 of embodiment 13-2 has at least one recess 11U on at least one of the outer surface and the inner surface of the side wall portion 11W. It should be noted that the number, arrangement, size, and shape of the recesses 11U are not limited to... Figure 54A The options shown can be chosen arbitrarily.

[0586] [Effect]

[0587] According to the outer packaging can 11 of method 13-2, since a recess 11U is provided on at least one of the outer surface and the inner surface of the side wall portion 11W, the surface area of ​​the side wall portion can be increased compared to an outer packaging can without a recess, resulting in high heat dissipation. Therefore, the heat generated by the battery reaction accompanying the built-in electrode winding can be effectively released to the outside. Therefore, in the battery using the outer packaging can 11 of method 13-2, temperature rise can be suppressed.

[0588] (13-3)

[0589] [structure]

[0590] Figure 54B This is a perspective view schematically illustrating the appearance of the outer packaging can 11 of embodiment 13-3, which can be applied to batteries such as lithium-ion secondary batteries. The outer packaging can 11 is a container that houses the positive electrode current collector, the negative electrode current collector, and the electrode winding. Ideally, the structural material of the outer packaging can 11 is a material with high thermal conductivity and high rigidity, specifically, a metallic material such as iron. The outer packaging can 11 has a bottom 11B and a side wall portion 11W. The outer packaging can 11 of embodiment 13-3 has at least one protrusion 11T on at least one of the outer surface and the inner surface of the side wall portion 11W. It should be noted that the number, arrangement, size, and shape of the protrusions 11T are not limited to... Figure 54B The options shown can be chosen arbitrarily.

[0591] [Effect]

[0592] According to the outer packaging can 11 of method 13-3, since a protrusion 11T is provided on at least one of the outer surface and the inner surface of the side wall portion 11W, the surface area of ​​the side wall portion can be increased compared with an outer packaging can without a protrusion, thus achieving high heat dissipation. Therefore, the heat generated by the battery reaction accompanying the built-in electrode winding can be effectively released to the outside. Therefore, in the battery using the outer packaging can 11 of method 13-3, temperature rise can be suppressed.

[0593] (13-4)

[0594] [structure]

[0595] Figure 54CThis is a perspective view schematically illustrating the appearance of the outer packaging can 11, which can be applied to batteries such as lithium-ion secondary batteries, according to method 13-4. The outer packaging can 11 is a container that houses a positive electrode current collector, a negative electrode current collector, and an electrode winding. Ideally, the structural material of the outer packaging can 11 is a material with high thermal conductivity and high rigidity, specifically, a metallic material such as iron. The outer packaging can 11 has a bottom 11B and a side wall portion 11W. The outer packaging can 11 of method 13-4 has at least one groove 11G on at least one of the outer surface and the inner surface of the side wall portion 11W. The groove 11G is, for example, arranged to surround the outer surface of the side wall portion 11W of the outer packaging can 11. It should be noted that the number, arrangement, and width of the grooves 11G are not limited. Figure 54C The options shown can be chosen arbitrarily.

[0596] [Effect]

[0597] According to the outer packaging can 11 of method 13-4, since a groove 11G is provided on at least one of the outer surface and the inner surface of the side wall portion 11W, the surface area of ​​the side wall portion can be increased compared to an outer packaging can without a groove 11G, resulting in high heat dissipation. Therefore, the heat generated by the battery reaction accompanying the built-in electrode winding can be effectively released to the outside. Therefore, in the battery using the outer packaging can 11 of method 13-4, temperature rise can be suppressed.

[0598] The present disclosure has been described above with reference to one embodiment and several modifications, but the structure of the present disclosure is not limited to the structure described in the above embodiment and several modifications, and various modifications can be made.

[0599] Furthermore, while the above description addresses the case where lithium is used as the electrode reactant, this is not specifically limited. Therefore, as mentioned above, the electrode reactant can be other alkali metals such as sodium and potassium, or alkaline earth metals such as beryllium, magnesium, and calcium. Additionally, the electrode reactant can also be other light metals such as aluminum.

[0600] The effects described in this specification are merely illustrative, and the effects of this disclosure are not limited to those described herein. Therefore, other effects can be obtained with respect to this disclosure.

[0601] 1: Lithium-ion secondary battery; 11: Outer packaging can; 11B: Bottom; 11N: Open end; 11P: Bending part; 11R: Riveting structure; 11S: Reduced diameter part; 11W: Side wall part; 11WS: Side; 12, 13: Insulating plate; 14: Battery cover; 14T: Protrusion; 15: Gasket; 20: Electrode winding body; S20: Laminated body; 21: Positive electrode; 21A: Positive electrode current collector 21B: Positive electrode active material layer; 21BT1: First edge; 211: Positive electrode covered area; 212: Positive electrode exposed area; 212E: Positive electrode edge; 21E1: Center-side edge of the coil; 21E2: Outer peripheral edge of the coil; 22: Negative electrode; 22A: Negative electrode current collector; 22B: Negative electrode active material layer; 221: Negative electrode covered area; 222: Negative electrode exposed area; 222E: Negative electrode active material layer; 221: Negative electrode covered area; 222: Negative electrode exposed area; 222E: Negative electrode active material layer; 21B: Positive electrode active material layer; 21B: Positive electrode covered area; 21B: Positive electrode exposed area; 21B: Positive electrode active material layer; 21B: Positive electrode active material layer; 21B: Positive electrode covered area; 21B: Positive electrode exposed area; 21B: Positive electrode active material layer; 21B: Positive electrode active material layer; 21B: Positive electrode active material layer; 21B: Positive electrode covered area; 21B: Positive electrode exposed ... exposed area; 21B: Positive electrode exposed area; 21B: Positive electrode exposed area; 21B: Positive electrode exposed area; 21B: Positive electrode exposed area; 21B: Positive electrode exposed area; 21B: Po 22E1: Central shaft side edge; 22E2: Outer peripheral side edge; 23: Diaphragm; 23A: First diaphragm component; 23B: Second diaphragm component; 24: Positive current collector; 25: Negative current collector; 26: Through hole; 30: Safety valve mechanism; 31, 33: Fan-shaped portion; 32, 34: Strip-shaped portion; 35, 36: Opening; 41: Upper end face; 41G1, 41G2: Groove Part; 42: Lower end face; 46: Fixing strap; 50: Outer packaging tube; 53, 54: Insulating tape; 55: Gasket; 55K: Opening; 61: First joint; 61A: First linear portion; 61B: First fold-back portion; 62: Second joint; 62A: Second linear portion; 62B: Second fold-back portion; 101: Insulating layer; 300: Battery pack; CL: Central axis; K: Boundary.

Claims

1. A secondary battery, comprising: An electrode winding body, comprising a stack of a first electrode, a second electrode, and a diaphragm, is wound along the long side direction of the stack, and the electrode winding body has a through hole extending in a width direction orthogonal to the long side direction; and The first electrode current collector plate and the second electrode current collector plate sandwich the electrode winding body in the width direction and are positioned opposite each other. The first electrode current collector plate includes an opening at the position in the width direction where it coincides with the through hole. The diameter of the opening is smaller than the diameter of the through hole.

2. The secondary battery according to claim 1, wherein, A first bent portion is provided at the periphery of the opening of the first electrode current collector plate, bending into the through hole.

3. The secondary battery according to claim 2, wherein, A first recess is provided in the through hole, and the first bent portion covers at least a portion of the first recess.

4. The secondary battery according to claim 3, wherein, The first electrode has a first electrode current collector and a first electrode active material layer covering a portion of the first electrode current collector. The first electrode includes a first electrode covered area and a first electrode exposed area. In the first electrode covered area, the first electrode current collector is covered by the first electrode active material layer. In the first electrode exposed area, the first electrode current collector is exposed and not covered by the first electrode active material layer. The first electrode exposed area is adjacent to the first electrode covered area in the width direction and is coupled to the first electrode current collector plate. The first recess is formed in the compression portion of the first electrode current collector in the first electrode exposed area where multiple portions overlap.

5. A secondary battery, comprising: An electrode winding body, comprising a laminate of a first electrode, a second electrode, and a diaphragm, is wound along the long side direction of the laminate and has a through hole extending in a width direction orthogonal to the long side direction; and The first electrode current collector plate and the second electrode current collector plate sandwich the electrode winding body in the width direction and are positioned opposite each other. A second bending portion is provided on the outer periphery of the first electrode current collector plate, which bends toward the second electrode current collector plate.

6. The secondary battery according to claim 5, wherein, A second recess is provided on the outer surface of the electrode winding body, and the second bent portion covers at least a portion of the second recess.

7. The secondary battery according to claim 6, wherein, The first electrode has a first electrode current collector and a first electrode active material layer covering a portion of the first electrode current collector. The first electrode includes a first electrode covered area and a first electrode exposed area. In the first electrode covered area, the first electrode current collector is covered by the first electrode active material layer. In the first electrode exposed area, the first electrode current collector is exposed and not covered by the first electrode active material layer. The first electrode exposed area is adjacent to the first electrode covered area in the width direction and is coupled to the first electrode current collector plate. The second recess is formed in the compression portion of the first electrode current collector in the exposed area of ​​the first electrode, where multiple portions overlap.

8. The secondary battery according to claim 1, wherein, The first electrode has a first electrode current collector and a first electrode active material layer covering a portion of the first electrode current collector. The first electrode includes a first electrode covered area and a first electrode exposed area. In the first electrode covered area, the first electrode current collector is covered by the first electrode active material layer. In the first electrode exposed area, the first electrode current collector is exposed and not covered by the first electrode active material layer. The first electrode exposed area is adjacent to the first electrode covered area in the width direction and is coupled to the first electrode current collector plate. The second electrode has a second electrode current collector and a second electrode active material layer covering a portion of the second electrode current collector. The second electrode includes a second electrode covered area and a second electrode exposed area. In the second electrode covered area, the second electrode current collector is covered by the second electrode active material layer. In the second electrode exposed area, the second electrode current collector is exposed and not covered by the second electrode active material layer. The second electrode exposed area is adjacent to the second electrode covered area in the width direction and is joined to the second electrode current collector plate. The maximum thickness of the first compressed portion, in which multiple parts of the first electrode current collector overlap in the first electrode exposed area, is greater than the maximum thickness of the second compressed portion, in which multiple parts of the second electrode current collector overlap in the second electrode exposed area.

9. The secondary battery according to claim 1, wherein, The electrode winding has a first end face that is orthogonal to the width direction and opposite to the first electrode current collector. The first electrode current collector includes a first portion extending along the first end face and a second portion protruding from the first portion in a first direction. Among the multiple joints that join the first part and the first end face, the joint closest to the second part has a length in a second direction orthogonal to the first direction that is greater than or equal to the length of the second part in the second direction.

10. A secondary battery, comprising: An electrode winding body, comprising a stack of a first electrode, a second electrode, and a diaphragm, is wound along the long side direction of the stack, and the electrode winding body has a through hole extending in a width direction orthogonal to the long side direction; and The first electrode current collector plate and the second electrode current collector plate sandwich the electrode winding body in the width direction and are positioned opposite each other. The first electrode has a first electrode current collector, a base coating covering the first electrode current collector, and a first electrode active material layer covering a portion of the base coating. The second electrode has a second electrode current collector and a second electrode active material layer covering the second electrode current collector. In the width direction, the end edge of the first electrode active material layer is located at a position set back from the end edge of the base layer, and the end edge of the second electrode active material layer is located between the end edge of the base layer and the end edge of the first electrode active material layer.

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