Battery roll core structure and battery

Abstract

This application discloses a battery core structure and a battery. The battery core structure includes a positive electrode sheet and a negative electrode sheet, which are stacked and wound into a cylindrical shape. A positive electrode tab is provided in the middle of the positive electrode sheet and is electrically connected to it. A first negative electrode tab is provided in the middle of the negative electrode sheet, and a second negative electrode tab is provided at the tail end of the negative electrode sheet. The tail end is the end of the battery core structure away from the center of the battery core structure. Both the first and second negative electrode tabs are electrically connected to the negative electrode sheet. The positive electrode tab and the first negative electrode tab are radially offset from each other in the battery core structure. The battery includes a casing and the battery core structure, which is disposed within the casing. This application improves the problem of inward collapse and deformation of the electrode sheet, enhances the uniformity of current distribution on the electrode sheet, improves current distribution, shortens the movement and diffusion paths of electrons and ions, and effectively improves the battery's rate performance and cycle life.

Description

Technical Field

[0001] This application belongs to the field of battery technology, and more specifically, this application relates to a battery core structure and a battery. Background Technology

[0002] In the current manufacturing process of cylindrical batteries, a positive or negative tab is typically welded to the head of the electrode. This manufacturing process presents a potential problem: during the later stages of charge-discharge cycles, the battery core tends to collapse inward toward the center hole. This inward collapse and deformation of the electrode leads to poor contact between the electrodes, resulting in lithium plating and performance degradation. Furthermore, the inward deformation causes the separator between the positive and negative electrodes to be stretched, leading to accelerated aging and a risk of puncturing the separator and causing a short circuit between the positive and negative electrodes. Utility Model Content

[0003] The embodiments of this application provide a battery core structure and battery. Tabs are provided at the middle and end of the electrode sheet, while the head of the electrode sheet has no tabs. This ensures that the displacement of the electrode sheet towards the innermost ring is not obstructed, allowing stress to be released promptly and improving the problem of inward deformation and collapse of the electrode sheet. A positive tab and one of the negative tabs are located in the middle of the electrode sheet, subject to interlayer compression from the positive and negative electrode sheets, resulting in better interface contact and stability. The presence of one positive tab and two negative tabs improves the uniformity of current distribution on the electrode sheet, enhances current distribution, shortens the movement and diffusion paths of electrons and ions, and effectively improves the battery's rate performance and cycle life.

[0004] To achieve the aforementioned technical objectives, the first aspect of this application discloses a battery core structure, comprising a positive electrode sheet and a negative electrode sheet stacked and wound into a cylindrical shape. A positive electrode tab is provided in the middle of the positive electrode plate, and the positive electrode tab is electrically connected to the positive electrode plate. The negative electrode sheet has a first negative electrode tab in the middle and a second negative electrode tab at the tail end. The tail end is the end of the battery core structure away from the center of the battery core structure. Both the first negative electrode tab and the second negative electrode tab are electrically connected to the negative electrode sheet. The positive electrode tab is offset from the first negative electrode tab in the radial direction of the battery core structure.

[0005] To achieve the above-mentioned technical objectives, a second aspect of this application discloses a battery, including a housing and the battery core structure described in the first aspect, wherein the battery core structure is disposed within the housing.

[0006] The beneficial effects of this application are as follows: The battery core structure and battery of this application have tabs at the middle and end of the electrode sheet, and no tabs at the head of the electrode sheet. The displacement of the electrode sheet towards the innermost circle is not blocked, and the stress is released in time, which improves the problem of the electrode sheet's concave collapse and deformation. The positive tab and one of the negative tabs are located in the middle of the electrode sheet, and are subject to the interlayer extrusion force of the positive and negative electrode sheets, resulting in better interface contact and stability. The presence of one positive tab and two negative tabs improves the uniformity of current distribution on the electrode sheet, improves current distribution, shortens the movement and diffusion paths of electrons and ions, and effectively improves the battery's rate performance and cycle life. Attached Figure Description

[0007] Figure 1 This is a schematic diagram of the battery core structure in an embodiment of this application when it is not wound.

[0008] Figure 2 This is a schematic diagram of the battery core structure of another embodiment of this application (excluding the separator).

[0009] Figure 3 This is a schematic diagram of the inner surface of the positive electrode sheet according to an embodiment of this application.

[0010] Figure 4 This is a schematic diagram of the inner surface of the negative electrode sheet according to an embodiment of this application.

[0011] In the picture, 1. Positive electrode sheet; 11. Positive current collector; 12. First positive active material layer; 13. Second positive active material layer; 14. Third positive active material layer; 15. Fourth positive active material layer; 2. Negative electrode sheet; 21. Negative current collector; 22. First negative active material layer; 23. Second negative active material layer; 24. Third negative active material layer; 25. Fourth negative active material layer; 3. Positive electrode tab; 41. First negative electrode tab; 42. Second negative electrode tab; 51. First insulating protective layer; 52. Second insulating protective layer; 53. Third insulating protective layer; 54. Fourth insulating protective layer; 6. Separator; 61. First adhesive layer; 62. Base film; 63. Ceramic layer; 64. Second adhesive layer. Detailed Implementation

[0012] The battery core structure provided in this application will be explained and described in detail below with reference to the accompanying drawings.

[0013] This embodiment specifically discloses a battery core structure, such as... Figures 1-2As shown, it includes a positive electrode 1 and a negative electrode 2 that are stacked and wound into a column shape. After winding, one of the positive electrode 1 and the negative electrode 2 is disposed on the inner side of the other. For example, the positive electrode 1 can be disposed on the inner side of the negative electrode 2, and the positive electrode 1 can also be disposed on the outer side of the negative electrode 2. Preferably, the positive electrode 1 is disposed on the outer side of the negative electrode 2. A positive electrode tab 3 is provided in the middle of the positive electrode 1. The positive electrode tab 3 is electrically connected to the positive electrode 1. The positive electrode tab 3 can be provided on the inner surface or the outer surface of the positive electrode 1. In this embodiment, the inner surface of the electrode refers to the surface near the center of the battery core structure, and the outer surface of the electrode refers to the surface away from the center of the battery core structure. A first negative electrode tab 41 is provided in the middle of the negative electrode 2, and a second negative electrode tab 42 is provided at the tail end of the negative electrode 2. The tail end is the end of the battery core structure away from the center of the battery core structure, and the head end is the end of the battery core structure near the center of the battery core structure. Both the first negative electrode tab 41 and the second negative electrode tab 42 are electrically connected to the negative electrode 2. The first negative electrode tab 41 can be provided on the inner surface or the outer surface of the negative electrode 2, and the second negative electrode tab 42 can be provided on the inner surface or the outer surface of the negative electrode 2. The positive electrode tab 3 and the first negative electrode tab 41 are offset radially from each other in the battery core structure to avoid short circuit between the positive electrode tab 3 and the first negative electrode tab 41.

[0014] Preferably, the positive electrode tab 3 and the first negative electrode tab 41 are distributed on both sides of the center of the battery core structure and are arranged opposite each other to facilitate connection with external circuits.

[0015] The reason why the battery core structure undergoes inward collapse and cyclic deformation in the later stages of charge-discharge cycles is that during the cycle, the expansion and displacement of the electrode sheets cause the battery core structure to be subjected to two forces: the internal pressure of the outer casing and the friction between the positive and negative electrode sheets. These two forces eventually concentrate on the innermost ring of the battery core structure. If the innermost ring has a head tab, the cyclic displacement of the electrode sheets will be blocked by the internal head tab, and the stress on the electrode sheets cannot be released, ultimately causing the inner ring electrode sheets to fold and deform to release the stress.

[0016] This application provides tabs at the middle and tail of the electrode sheet, while the head of the electrode sheet is free of tabs. This ensures that the displacement of the electrode sheet towards the innermost ring is not blocked, and stress is released in a timely manner, improving the problem of inward collapse and deformation of the electrode sheet. The positive tab 3 and one of the negative tabs are located in the middle of the electrode sheet and are subject to interlayer compression force from the positive electrode sheet 1 and the negative electrode sheet 2, resulting in better interface contact and stability. The provision of one positive tab 3 and two negative tabs improves the uniformity of current distribution on the electrode sheet, improves current distribution, shortens the movement and diffusion paths of electrons and ions, and effectively improves the rate performance and cycle life of the battery.

[0017] This application provides only one positive electrode tab 3, which effectively avoids lithium plating compared to providing two positive electrode tabs 3. Since the current is mainly transferred from the negative electrode during battery charging and discharging, if two positive electrode tabs 3 are provided, the current will concentrate too quickly on the positive electrode, resulting in lithium ions not being properly inserted into the negative electrode material and metallic lithium being deposited on the surface of the negative electrode.

[0018] The length of the positive electrode 1 from its head to its tail is L1. The positive electrode tab 3 can be located at 1 / 3L1 to 2 / 3L1 of the positive electrode 1. Preferably, the positive electrode tab 3 is located at 1 / 2L1 of the positive electrode 1. The length of the negative electrode 2 from its head to its tail is L2. The first negative electrode tab 41 can be located at 1 / 3L2 to 2 / 3L2 of the negative electrode 2. Preferably, the first negative electrode tab 41 is located at 1 / 2L2 of the negative electrode 2.

[0019] In some alternative embodiments, such as Figure 1 As shown, the battery core structure also includes a separator 6, which is stacked between the positive electrode 1 and the negative electrode 2. The separator 6 separates the positive electrode 1 and the negative electrode 2, preventing short circuits between them. The separator 6 includes a first adhesive layer 61, a base film 62, a ceramic layer 63, and a second adhesive layer 64 arranged radially along the battery core structure. Adhesive layers are provided on both the inner and outer sides of the separator 6 to improve adhesion to the electrode sheets, thereby improving the safety of the battery core structure. The base film 62 may include one of polyethylene, non-woven fabric, and polypropylene. The ceramic layer 63 may include ceramic particles, which may include at least one of alumina, zirconium dioxide, titanium dioxide, boehmite, and silicon dioxide. The ceramic particles can be bonded together with an adhesive to form the ceramic layer 63. The adhesive may be polyvinylidene fluoride, styrene-butadiene rubber, waterborne polyurethane, etc. The ceramic layer 63 increases the puncture resistance and thermal deformation of the separator 6. The oxide ceramic layer 63 has good wettability and liquid absorption and retention capabilities, which can improve the cycle performance of the battery core structure. The boehmite ceramic layer 63 can improve the heat resistance and puncture resistance of the separator 6, and improve the safety performance and energy density of the battery core structure.

[0020] In one embodiment, the first adhesive layer 61 is bonded to the positive electrode 1, and the second adhesive layer 64 is bonded to the negative electrode 2. The puncture resistance on the ceramic layer 63 side is higher than that on the base film 62 side. After the positive electrode 1 and the negative electrode 2 are wound, the head end of the negative electrode 2 can protrude beyond the head end of the positive electrode 1 (i.e., the head end of the positive electrode 1 is located between the head end of the negative electrode 2 and the interlayer formed by the adjacent negative electrode 2). At this time, the head end of the positive electrode 1 exerts a greater force on the separator 6. The first adhesive layer 61 is bonded to the positive electrode 1, and the second adhesive layer 64 is bonded to the negative electrode 2. The ceramic layer 63 is closer to the positive electrode 1, which can improve the puncture resistance of the separator 6 on the side closer to the positive electrode 1, prevent the separator 6 from being punctured by the head end of the positive electrode 1, and thus improve the safety performance of the battery core structure.

[0021] In another embodiment, the first adhesive layer 61 is bonded to the negative electrode 2, and the second adhesive layer 64 is bonded to the positive electrode 1. After the positive electrode 1 and the negative electrode 2 are wound, the head end of the positive electrode 1 can protrude beyond the head end of the negative electrode 2 (i.e., the head end of the negative electrode 2 is located between the head end of the positive electrode 1 and the layer formed by the adjacent positive electrode 1). At this time, the head end of the negative electrode 2 exerts a greater force on the separator 6. The first adhesive layer 61 is bonded to the negative electrode 2, and the second adhesive layer 64 is bonded to the positive electrode 1. The ceramic layer 63 is closer to the negative electrode 2, which can improve the puncture resistance of the separator 6 on the side closer to the negative electrode 2, prevent the separator 6 from being punctured by the head end of the negative electrode 2, and thus improve the safety performance of the battery core structure.

[0022] Preferably, the first adhesive layer 61 is bonded to the negative electrode 2, and the second adhesive layer 64 is bonded to the positive electrode 1. Typically, the length of the positive electrode 1 is shorter than that of the negative electrode 2. The head of the positive electrode 1 is located between the head of the negative electrode 2 and the adjacent negative electrode 2. The ceramic layer 63 is closer to the positive electrode 1. The ceramic layer 63 improves the puncture resistance of the separator 6 on the side closer to the positive electrode 1, thereby improving the safety performance of the battery core structure and saving costs.

[0023] Optionally, the first adhesive layer 61 includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, carboxymethyl cellulose, styrene-butadiene rubber, polyimide, and sodium carboxymethyl cellulose, and the second adhesive layer 64 includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, carboxymethyl cellulose, styrene-butadiene rubber, polyimide, and sodium carboxymethyl cellulose. The materials of the first adhesive layer 61 and the second adhesive layer 64 can be the same or different. Both the first adhesive layer 61 and the second adhesive layer 64 have good adhesion, improving the safety of the battery core structure.

[0024] Preferably, the first adhesive layer 61 comprises polyvinylidene fluoride (PVDF), and the second adhesive layer 64 comprises PVDF, exhibiting good adhesion. After the battery core structure is manufactured or the battery is manufactured, the battery core structure or battery is stored at a high temperature of 60°C for 6 hours to activate the adhesion of the first adhesive layer 61 and the second adhesive layer 64, thereby improving the safety of the battery core structure.

[0025] Optionally, the length of the separator 6 from its head to its tail is greater than the length of the positive electrode 1 from its head to its tail, and the length of the separator 6 from its head to its tail is greater than the length of the negative electrode 2 from its head to its tail. The tail end of the separator 6 protrudes outward from the tail ends of the positive electrode 1 and the negative electrode 2, so that the battery core structure is finished with the separator 6 after winding, improving heat dissipation. Furthermore, the adhesive properties of the separator 6 are used to fix the tail ends of the positive electrode 1 and the negative electrode 2, improving the safety of the battery core structure. The head end of the separator 6 can be flush with the more protruding head end of the head ends of the positive electrode 1 and the negative electrode 2, or the head end of the separator 6 can protrude beyond the head ends of the positive electrode 1 and the negative electrode 2.

[0026] In some alternative embodiments, such as Figures 1-3 As shown, the positive electrode 1 has a first empty foil area on both the inner and outer surfaces of its head. The head is the end of the battery core structure near the center of the battery core structure. The positive electrode 1 has a second empty foil area on both the inner and outer surfaces of its tail. The first empty foil area has a first insulating protective layer 51, and the second empty foil area has a second insulating protective layer 52. The positive electrode 1 includes a positive current collector 11 and positive active material layers disposed on the inner and outer surfaces of the positive current collector 11. The area on the positive current collector 11 without a positive active material layer is the empty foil area. In this embodiment, the positive current collector 11 of the positive electrode 1 can be aluminum foil, and the active material of the positive active material layer can include at least one of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide. The lengths of the first empty foil areas on the inner and outer surfaces of the head of the positive electrode 1 can be the same or different, and the lengths of the second empty foil areas on the inner and outer surfaces of the tail of the positive electrode 1 can be the same or different. In this embodiment, length refers to the dimension along the direction from the head to the tail of the electrode. The lengths of the first and second empty foil regions can be set as needed, and this application does not impose any special limitations. The inner and outer surfaces of the head and the tail of the negative electrode 2 may be provided with an insulating protective layer, or they may not be provided with an insulating protective layer (the inner and outer surfaces of the head and the tail of the negative electrode 2 are both negative electrode active material layers).

[0027] After the positive electrode 1 and the negative electrode 2 are wound together, the head end of the positive electrode 1 can protrude outward from the head end of the negative electrode 2, and the head end of the negative electrode 2 can also protrude outward from the head end of the positive electrode 1. The head ends of the positive electrode 1 and the negative electrode 2 can also be flush. The tail end of the positive electrode 1 can protrude outward from the tail end of the negative electrode 2, and the tail end of the negative electrode 2 can also protrude outward from the tail end of the positive electrode 1. The tail ends of the positive electrode 1 and the negative electrode 2 can also be flush.

[0028] When the head end of the positive electrode 1 protrudes outward beyond the head end of the negative electrode 2, the projection of the head end face of the negative electrode 2 radially along the battery core structure onto the positive electrode 1 falls on the first insulating protective layer 51, preventing the head end of the negative electrode 2 from contacting the positive electrode 1 and causing a short circuit. When the tail end of the positive electrode 1 protrudes outward beyond the tail end of the negative electrode 2, the projection of the tail end face of the negative electrode 2 radially along the battery core structure onto the positive electrode 1 falls on the second insulating protective layer 52, preventing the tail end of the negative electrode 2 from contacting the positive electrode 1 and causing a short circuit. Especially when a separator 6 is provided between the positive electrode 1 and the negative electrode 2, even if the end of the negative electrode 2 punctures the separator 6, the end of the negative electrode 2 will not contact the positive electrode 1 and cause a short circuit, ensuring the safety of the battery core structure.

[0029] When the head end of the negative electrode 2 protrudes outward from the head end of the positive electrode 1, or when the head end of the positive electrode 1 and the head end of the negative electrode 2 are flush, and the tail end of the negative electrode 2 protrudes outward from the tail end of the positive electrode 1, or when the tail end of the positive electrode 1 and the tail end of the negative electrode 2 are flush, the insulating protective layer at the head and tail of the positive electrode 1 can replace the sharp active material originally provided at the end of the positive electrode 1, avoiding short circuit between the positive electrode 1 and the negative electrode 2 caused by the end of the positive electrode 1 piercing the separator 6, thus maximizing the safety of the battery core structure.

[0030] In summary, the embodiments of this application provide insulating protective layers at the head and tail of the positive electrode 1, which protect the end of the positive electrode 1 and prevent short circuits caused by contact between the end of the positive electrode 1 and the negative electrode 2. Especially when a separator 6 is provided between the positive electrode 1 and the negative electrode 2, the insulating protective layers at the head and tail of the positive electrode 1 can prevent short circuits between the positive electrode 1 and the negative electrode 2 caused by the end of the positive electrode 1 piercing the separator 6, thus maximizing the safety of the battery core structure.

[0031] In some alternative embodiments, such as Figure 1 , Figure 2 and Figure 4 As shown, the negative electrode 2 has a third empty foil area on both the inner and outer surfaces of its head, and a fourth empty foil area on both the inner and outer surfaces of its tail. A third insulating protective layer 53 is provided in the third empty foil area, and a fourth insulating protective layer 54 is provided in the fourth empty foil area. The negative electrode 2 includes a negative current collector 21 and negative active material layers disposed on the inner and outer surfaces of the negative current collector 21. The area on the negative current collector 21 without a negative active material layer is the empty foil area. In this embodiment, the negative current collector 21 of the negative electrode 2 can be copper foil, and the active material of the negative active material layer can include at least one of graphite, lithium titanate, carbon materials, and tin-based oxides. The lengths of the third empty foil areas on the inner and outer surfaces of the head of the negative electrode 2 can be the same or different, and the lengths of the fourth empty foil areas on the inner and outer surfaces of the tail of the positive electrode 1 can be the same or different. The lengths of the third and fourth empty foil areas can be set as needed, and this application does not impose any special limitations. A first insulating protective layer 51 may be provided on the inner and outer surfaces of the head of the positive electrode 1, and a second insulating protective layer 52 may be provided on the inner and outer surfaces of the tail of the positive electrode 1; the inner and outer surfaces of the head and the tail of the positive electrode 1 may also be without an insulating protective layer.

[0032] In some optional embodiments, the positive electrode 1 has a first empty foil area on both the inner and outer surfaces of its head, and a second empty foil area on both the inner and outer surfaces of its tail. A first insulating protective layer 51 is provided in the first empty foil area, and a second insulating protective layer 52 is provided in the second empty foil area. The negative electrode 2 has a third empty foil area on both the inner and outer surfaces of its head, and a fourth empty foil area on both the inner and outer surfaces of its tail. A third insulating protective layer 53 is provided in the third empty foil area, and a fourth insulating protective layer 54 is provided in the fourth empty foil area. The specific features are consistent with those described in the above embodiments and will not be repeated here.

[0033] When the head end of the negative electrode 2 protrudes outward from the head end of the positive electrode 1, the projection of the head end face of the positive electrode 1 radially along the battery core structure onto the negative electrode 2 falls on the third insulating protective layer 53, preventing the head end of the positive electrode 1 from contacting the negative electrode 2 and causing a short circuit. When the tail end of the negative electrode 2 protrudes outward from the tail end of the positive electrode 1, the projection of the tail end face of the positive electrode 1 radially along the battery core structure onto the negative electrode 2 falls on the fourth insulating protective layer 54, preventing the tail end of the positive electrode 1 from contacting the negative electrode 2 and causing a short circuit. Especially when a separator 6 is provided between the positive electrode 1 and the negative electrode 2, even if the end of the positive electrode 1 punctures the separator 6, the end of the positive electrode 1 will not contact the negative electrode 2 and cause a short circuit, ensuring the safety of the battery core structure.

[0034] When the head end of the positive electrode 1 protrudes outward beyond the head end of the negative electrode 2, or when the head end of the negative electrode 2 is flush with the head end of the positive electrode 1, and the tail end of the positive electrode 1 protrudes outward beyond the tail end of the negative electrode 2, or when the tail end of the negative electrode 2 is flush with the tail end of the positive electrode 1, the insulating protective layer at the head and tail of the negative electrode 2 replaces the sharp active material originally provided at the end of the negative electrode 2, thus preventing the end of the negative electrode 2 from piercing the separator 6 and causing a short circuit between the positive electrode 1 and the negative electrode 2, and maximizing the safety of the battery core structure.

[0035] In summary, the embodiments of this application provide insulating protective layers at the head and tail of the negative electrode 2, which protect the end of the negative electrode 2 and prevent short circuits caused by contact between the end of the negative electrode 2 and the positive electrode 1. Especially when a separator 6 is provided between the positive electrode 1 and the negative electrode 2, the insulating protective layers at the head and tail of the negative electrode 2 can prevent short circuits between the positive electrode 1 and the negative electrode 2 caused by the end of the negative electrode 2 piercing the separator 6, thus maximizing the safety of the battery core structure.

[0036] In some preferred embodiments, the inner and outer surfaces of the head of the positive electrode 1 are provided with a first insulating protective layer 51, and the inner and outer surfaces of the tail of the positive electrode 1 are provided with a second insulating protective layer 52. The inner and outer surfaces of the head of the negative electrode 2 are provided with a third insulating protective layer 53, and the inner and outer surfaces of the tail of the negative electrode 2 are provided with a fourth insulating protective layer 54.

[0037] In this embodiment, insulating protective layers are provided at both the head and tail of the positive electrode 1 and the negative electrode 2, which protect the ends of the positive electrode 1 and the negative electrode 2 and prevent short circuits from occurring due to end contact. Especially when a separator 6 is provided between the positive electrode 1 and the negative electrode 2, the insulating protective layer replaces the sharp active material originally provided at the ends of the positive electrode 1 and the negative electrode 2, preventing short circuits caused by the ends of the positive electrode 1 and the negative electrode 2 piercing the separator 6, thus maximizing the safety of the battery core structure. Regardless of whether the head end of the positive electrode 1 or the head end of the negative electrode 2 protrudes more outward, or whether the tail end of the positive electrode 1 or the tail end of the negative electrode 2 protrudes more outward, the embodiments of this application can prevent the ends of the electrodes from piercing the separator 6, thus maximizing the safety of the battery core structure and providing more options for setting the lengths of the positive electrode 1 and the negative electrode 2.

[0038] In some alternative embodiments, such as Figure 1 and Figure 2 As shown, the length of the positive electrode 1 from its head to its tail is less than the length of the negative electrode 2 from its head to its tail. The head of the negative electrode 2 protrudes outward from the head of the positive electrode 1, and the tail of the negative electrode 2 protrudes outward from the tail of the positive electrode 1. As the main electrode from which current flows out, the negative electrode 2 needs to carry a larger current to meet the requirements of high-rate charging and discharging. Figure 2 As shown, the projection of the front end face of the positive electrode 1 onto the negative electrode 2 along the radial direction of the battery core structure falls on the third insulating protective layer 53, and the projection of the rear end face of the positive electrode 1 onto the negative electrode 2 along the radial direction of the battery core structure falls on the fourth insulating protective layer 54. This prevents the end of the positive electrode 1 from piercing the separator 6 and coming into contact with the negative electrode 2, thus avoiding a short circuit and further improving the safety performance of the battery core structure.

[0039] Optionally, the first insulating protective layer 51 can be an insulating tape, an insulating coating, or other insulating material that can provide protection, provided on the positive current collector 11.

[0040] Optionally, the second insulating protective layer 52 can be an insulating tape, an insulating coating, or other insulating material that can provide protection, provided on the positive current collector 11.

[0041] Optionally, the third insulating protective layer 53 can be an insulating tape, an insulating coating, or other insulating material that can provide protection, provided on the negative electrode current collector 21.

[0042] Optionally, the fourth insulating protective layer 54 can be an insulating tape, an insulating coating, or other insulating material that can provide protection, provided on the negative current collector 21.

[0043] For example, in one embodiment, the first insulating protective layer 51, the second insulating protective layer 52, the third insulating protective layer 53, and the fourth insulating protective layer 54 are all made of insulating tape. The insulating tape is directly adhered to the surface of the current collector, making it simple to manufacture. Furthermore, the hardness of the insulating tape is lower than that of the positive and negative electrode active materials, effectively preventing the ends of the positive electrode plate 1 and the negative electrode plate 2 from puncturing the separator 6. The insulating tape can be polypropylene tape or polyethylene terephthalate (PET) tape.

[0044] Optional, such as Figures 1-3 As shown, a fifth empty foil region is provided on the inner surface of the middle part of the positive electrode sheet 1. A first positive electrode active material layer 12 and a second positive electrode active material layer 13 can be disposed on the inner surface of the positive electrode current collector 11. A gap is maintained between the first positive electrode active material layer 12 and the second positive electrode active material layer 13. The area between the first positive electrode active material layer 12 and the second positive electrode active material layer 13 is the fifth empty foil region. The first positive electrode active material layer 12 and the second positive electrode active material layer 13 are disposed between the first insulating protective layer 51 and the second insulating protective layer 52 on the inner surface of the positive electrode sheet 1. A sixth empty foil region is provided on the outer surface of the middle part of the positive electrode sheet 1. A third positive electrode active material layer 14 and a fourth positive electrode active material layer 15 can be disposed on the outer surface of the positive electrode current collector 11. The positive electrode active material layer 15, the third positive electrode active material layer 14, and the fourth positive electrode active material layer 15 are spaced apart. The area between the third positive electrode active material layer 14 and the fourth positive electrode active material layer 15 is the sixth empty foil area. The third positive electrode active material layer 14 and the fourth positive electrode active material layer 15 are disposed between the first insulating protective layer 51 and the second insulating protective layer 52 on the outer surface of the positive electrode sheet 1. The fifth empty foil area and the sixth empty foil area are arranged opposite each other. The positive electrode tab 3 is disposed in the fifth empty foil area or the sixth empty foil area. The lengths of the fifth empty foil area and the sixth empty foil area can be the same, and the two ends of the fifth empty foil area and the sixth empty foil area are aligned. Alternatively, the lengths of the fifth empty foil area and the sixth empty foil area can be different, and one end of the two empty foil areas is aligned. The positive electrode tab 3 may not completely fill the empty foil area in which it is located. The positive electrode tab 3 is welded to the positive electrode current collector 11. Adhesive tape can also be disposed on the surface of the positive electrode tab 3 away from the positive electrode current collector 11. The two ends of the adhesive tape are attached to the positive electrode active material layer at both ends of the empty foil area in which the positive electrode tab 3 is located. The tape reinforces the connection between the positive electrode tab 3 and the positive electrode current collector 11, and also serves as insulation and protection.

[0045] like Figure 1 , Figure 2 and Figure 4As shown, the inner surface of the negative electrode 2 has a seventh empty foil region. A first negative electrode active material layer 22 and a second negative electrode active material layer 23 can be disposed on the inner surface of the negative electrode current collector 21. A gap is maintained between the first negative electrode active material layer 22 and the second negative electrode active material layer 23. The area between the first negative electrode active material layer 22 and the second negative electrode active material layer 23 is the seventh empty foil region. The first negative electrode active material layer 22 and the second negative electrode active material layer 23 are disposed between the third insulating protective layer 53 and the fourth insulating protective layer 54 on the inner surface of the negative electrode 2. The outer surface of the negative electrode 2 has an eighth empty foil region. A third negative electrode active material layer 24 and a fourth negative electrode active material layer 25 can be disposed on the outer surface of the negative electrode current collector 21. Layer 25, with a gap maintained between the third negative electrode active material layer 24 and the fourth negative electrode active material layer 25, forms the eighth empty foil region. The third negative electrode active material layer 24 and the fourth negative electrode active material layer 25 are disposed between the third insulating protective layer 53 and the fourth insulating protective layer 54 on the outer surface of the negative electrode sheet 2. The seventh empty foil region and the eighth empty foil region are arranged opposite each other, and the first negative electrode tab 41 is disposed in either the seventh or eighth empty foil region. The seventh and eighth empty foil regions can have the same length, with their two ends aligned; alternatively, the lengths of the seventh and eighth empty foil regions can be different, with one end of each empty foil region aligned. The first negative electrode tab 41 may not completely fill the empty foil region it is located in. The first negative electrode tab 41 can be soldered to the negative electrode current collector 21. Adhesive tape can also be disposed on the surface of the first negative electrode tab 41 away from the negative electrode current collector 21, with both ends of the tape adhered to the negative electrode active material layers at the beginning and end of the empty foil region where the first negative electrode tab 41 is located. The tape reinforces the connection between the first negative electrode tab 41 and the negative electrode current collector 21, and also serves as insulation and protection.

[0046] The inner surface of the tail end of the negative electrode 2 is provided with a ninth empty foil area, and the outer surface of the tail end of the negative electrode 2 is provided with a tenth empty foil area. The ninth and tenth empty foil areas are arranged opposite to each other, and the second negative electrode tab 42 is disposed within the ninth or tenth empty foil area. The ninth and tenth empty foil areas can be disposed at the beginning end of the fourth empty foil area, the end end of the fourth empty foil area, or inside the fourth empty foil area. That is, the second negative electrode tab 42 can be disposed at the beginning end of the fourth insulating protective layer 54, the end end of the fourth insulating protective layer 54, or between the fourth insulating protective layer 54 and the negative electrode current collector 21. When the second negative electrode tab 42 is disposed at the beginning or end of the fourth insulating protective layer 54, the fourth insulating protective layer 54 can extend and cover the second negative electrode tab 42. The second negative electrode tab 42 can be soldered to the negative electrode current collector 21. The fourth insulating protective layer 54 reinforces the connection between the second negative electrode tab 42 and the negative electrode current collector 21 on the one hand, and plays an insulating and protective role on the other.

[0047] Preferably, the positive electrode tab 3 is disposed in the fifth empty foil area, the first negative electrode tab 41 is disposed in the seventh empty foil area, and the second negative electrode tab 42 is disposed in the ninth empty foil area. That is, the positive electrode tab 3 is disposed on the inner surface of the positive electrode sheet 1, and the first negative electrode tab 41 and the second negative electrode tab 42 are disposed on the inner surface of the negative electrode sheet 2. During winding, the deformation of the tab itself and the displacement and deformation of the electrode sheet are relatively small.

[0048] This application also discloses a battery, including a housing and the battery core structure described in the above embodiments, wherein the battery core structure is disposed within the housing.

[0049] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0050] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0051] In the description of this specification, the references to terms such as "this embodiment," "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any at least one embodiment or example. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0052] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0053] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and simple improvements made to the substantive content of this application should be included within the protection scope of this application.

Claims

1. A battery jelly-roll structure, characterized by, This includes positive and negative electrode sheets that are stacked and wound into a cylindrical shape. A positive electrode tab is provided in the middle of the positive electrode plate, and the positive electrode tab is electrically connected to the positive electrode plate. The negative electrode sheet has a first negative electrode tab in the middle and a second negative electrode tab at the tail end. The tail end is the end of the battery core structure away from the center of the battery core structure. Both the first negative electrode tab and the second negative electrode tab are electrically connected to the negative electrode sheet. The positive electrode tab is offset from the first negative electrode tab in the radial direction of the battery core structure.

2. The jelly-roll structure of claim 1, wherein, The positive electrode sheet has a first empty foil area on both its head and outer surfaces. The head is the end of the battery core structure near the center of the battery core structure. The positive electrode sheet has a second empty foil area on both its tail and outer surfaces. The first empty foil area has a first insulating protective layer, and the second empty foil area has a second insulating protective layer. And / or... The negative electrode sheet has a third empty foil area on both the inner and outer surfaces of the head and a fourth empty foil area on both the inner and outer surfaces of the tail. The third empty foil area has a third insulating protective layer and the fourth empty foil area has a fourth insulating protective layer.

3. The jelly-roll structure of claim 2, wherein, The first insulating protective layer is insulating tape, and / or the second insulating protective layer is insulating tape, and / or the third insulating protective layer is insulating tape, and / or the fourth insulating protective layer is insulating tape.

4. The battery core structure according to claim 1, characterized in that, The positive electrode sheet has a fifth empty foil region on its inner central surface and a sixth empty foil region on its outer central surface. The fifth and sixth empty foil regions are arranged opposite to each other, and the positive electrode tab is disposed within either the fifth or sixth empty foil region. The negative electrode sheet has a seventh empty foil region on its inner central surface and an eighth empty foil region on its outer central surface. The seventh and eighth empty foil regions are arranged opposite to each other, and the first negative electrode tab is disposed within either the seventh or eighth empty foil region. The inner surface of the tail of the negative electrode sheet is provided with a ninth empty foil area, and the outer surface of the tail of the negative electrode sheet is provided with a tenth empty foil area. The ninth empty foil area and the tenth empty foil area are arranged opposite to each other, and the second negative electrode tab is disposed in the ninth empty foil area or the tenth empty foil area.

5. The battery core structure according to claim 4, characterized in that, The positive electrode tab is disposed in the fifth empty foil area, the first negative electrode tab is disposed in the seventh empty foil area, and the second negative electrode tab is disposed in the ninth empty foil area.

6. The battery core structure according to claim 2, characterized in that, The length of the positive electrode from its head to its tail is less than the length of the negative electrode from its head to its tail. The head of the negative electrode protrudes outward from the head of the positive electrode, and the tail of the negative electrode protrudes outward from the tail of the positive electrode. The projection of the front end face of the positive electrode sheet radially along the battery core structure onto the negative electrode sheet falls on the third insulating protective layer, and the projection of the rear end face of the positive electrode sheet radially along the battery core structure onto the negative electrode sheet falls on the fourth insulating protective layer.

7. The battery core structure according to claim 1, characterized in that, The battery core structure also includes a separator, which is stacked between the positive electrode and the negative electrode. The separator includes a first adhesive layer, a base film, a ceramic layer, and a second adhesive layer arranged sequentially along the radial direction of the battery core structure. The first adhesive layer is bonded to the negative electrode sheet, and the second adhesive layer is bonded to the positive electrode sheet, or... The first adhesive layer is bonded to the positive electrode sheet, and the second adhesive layer is bonded to the negative electrode sheet.

8. The battery core structure according to claim 7, characterized in that, The first adhesive layer includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, carboxymethyl cellulose, styrene-butadiene rubber, polyimide, and sodium carboxymethyl cellulose, and the second adhesive layer includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, carboxymethyl cellulose, styrene-butadiene rubber, polyimide, and sodium carboxymethyl cellulose.

9. The battery core structure according to claim 7, characterized in that, The length of the separator from its head end to its tail end is greater than the length of the positive electrode from its head end to its tail end, and the length of the separator from its head end to its tail end is greater than the length of the negative electrode from its head end to its tail end. The tail end of the separator protrudes outward from the tail ends of the positive electrode and the negative electrode.

10. A battery, characterized in that, It includes a housing and a battery core structure as described in any one of claims 1-9, wherein the battery core structure is disposed within the housing.

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