Winding type battery cell and battery

Abstract

The winding type battery cell comprises a negative electrode plate, a positive electrode plate and a diaphragm, the positive electrode plate comprises a positive electrode main body part and a positive electrode coating, a plurality of transition areas and a plurality of positive electrode coating areas are arranged on the positive electrode main body part in a staggered manner, and the positive electrode coatings are arranged on the positive electrode main body part and positioned on the two sides of the positive electrode coating areas; the diaphragm is arranged between the positive plate and the negative plate, the winding type battery cell comprises a flat area and two corner areas, and in the corner areas of the inner ring of the winding type battery cell, a positive electrode coating is not arranged on the inner side of the transition area on the positive electrode main body part. According to the winding type battery cell and the battery, the positive electrode coating is not arranged on the inner side of the transition area on the positive electrode main body part, so that the CB value of the outer side of the negative electrode plate in the corner area is sufficient, the problem of lithium precipitation of the negative electrode in the corner area of the winding type battery cell can be improved, and expansion stress can be released in the uncoated area after the winding type battery cell circularly expands; and the deformation improvement cycle performance can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a winding type battery core and a battery. Background Art

[0002] With the development of science and technology, the application of new energy batteries is becoming more and more extensive. Lithium-ion batteries are widely used in consumer electronics and power fields due to their high energy density, fast charging capability and safety. Lithium-ion batteries have a large proportion of winding structure cells, which are formed by stacking positive electrode sheets, negative electrode sheets and separators and then winding them. Conventional winding structure cells are prone to lithium deposition at the negative electrode interface at the inner corner due to the difference in CB value (the ratio of excess negative electrode to positive electrode active material) at the negative electrode corner of the inner circle of the core, resulting in rapid cycle attenuation. At the same time, the winding structure cells are prone to deformation during the cycle, resulting in excessive thickness defects. Utility Model Content

[0003] The utility model aims to solve at least one of the technical problems existing in the prior art. To this end, the utility model proposes a wound cell and a battery, which solves the problem in the prior art that due to the difference in CB value at the negative electrode corner of the inner circle of the core, lithium deposition at the negative electrode interface is likely to occur at the inner circle corner, resulting in rapid cycle decay, and the wound structure cell is prone to deformation during the cycle, resulting in excessive thickness.

[0004] The wound battery cell according to the embodiment of the utility model comprises:

[0005] Negative electrode;

[0006] A positive electrode sheet, comprising a positive electrode main body and a positive electrode coating, wherein the positive electrode main body is provided with a plurality of transition zones and a plurality of positive electrode coating zones along the length direction of the positive electrode sheet, the plurality of transition zones and the plurality of positive electrode coating zones are arranged alternately, and the positive electrode coating is provided on both sides of the positive electrode main body located in the positive electrode coating zone and along the thickness direction of the positive electrode sheet;

[0007] A separator, disposed between the negative electrode sheet and the positive electrode sheet;

[0008] Among them, the negative electrode sheet, the separator and the positive electrode sheet are wound to form the wound battery cell, and the wound battery cell includes a flat area and two corner areas, and the two corner areas are respectively located on both sides of the flat area along the width direction of the wound battery cell. In the corner area of ​​the inner circle of the wound battery cell, the positive electrode main body located on the inner side of the transition zone is not provided with the positive electrode coating.

[0009] The wound battery cell according to the embodiment of the utility model has at least the following beneficial effects:

[0010] The positive electrode sheet, separator and negative electrode sheet are wound to form a wound battery cell. The positive electrode sheet is located in the inner circle of the wound battery cell and there is no dressing (no positive electrode coating) at the position inside the corner area, so that the CB value of the outer side of the negative electrode sheet in the corner area is sufficient, which can limit the number of lithium ions on the inner side of the positive electrode sheet in the corner area, thereby avoiding the situation of uneven distribution of lithium ions in the corner area, that is, there will be no situation where there are no vacant lithium insertion sites on the negative electrode sheet due to excessive lithium ions locally, thereby improving the problem of lithium precipitation of the negative electrode in the corner area of ​​the wound battery cell. Multiple transition zones and multiple positive electrode coating zones are arranged in an alternating manner, and the positive electrode main body is partially coated. After the wound battery cell expands in a cycle, the expansion stress can be released in the uncoated area (transition zone), which can improve deformation and enhance cycle performance.

[0011] According to some embodiments of the present invention, in the corner area of ​​the inner circle of the wound battery cell, the positive electrode coating is provided on the positive electrode main body and located on the outer side of the transition area.

[0012] According to some embodiments of the present invention, in the corner area of ​​the inner circle of the wound battery cell, the positive electrode coating is not provided on the outer side of the transition area on the positive electrode main body.

[0013] According to some embodiments of the present invention, the lengths of the plurality of positive electrode coating areas located in the inner circle of the wound battery core are consistent.

[0014] According to some embodiments of the present invention, the length of the plurality of positive electrode coating areas located in the inner circle of the wound battery cell is a, the width of the wound battery cell is b, and the thickness of the wound battery cell is c, then a=bc.

[0015] According to some embodiments of the utility model, the wound battery cell also includes a negative electrode ear and a positive electrode ear, the negative electrode ear is connected to the negative electrode sheet, the positive electrode ear is connected to the positive electrode main body, and the positive electrode coating is not provided on both sides of the connection between the positive electrode main body and the positive electrode ear along the thickness direction of the positive electrode sheet.

[0016] According to some embodiments of the present utility model, the positive electrode ear and the negative electrode ear are connected to the innermost circle position of the wound battery cell, and the plurality of transition zones are divided into a first transition zone, a second transition zone, a third transition zone, and an nth transition zone along the direction from the head to the tail of the positive electrode body and along the length direction of the positive electrode sheet. The thickness of the first transition zone is R1, the thickness of the second transition zone is R2, the thickness of the third transition zone is R3, the thickness of the nth transition zone is Rn, and the thickness of the positive electrode sheet is d1 , the thickness of the negative electrode sheet is d2, the thickness of the separator is d3, the thickness of the positive electrode ear is d4, and the thickness of the negative electrode ear is d5, then: R1=((d1+d2+2d3)+(d3+d4)÷2)×π, R2=((d1+d2+2d3)×2+(d3+d4)÷2)×π, R3=((d1+d2+2d3)×3+(d3+d4)÷2)×π, Rn=((d1+d2+2d3)×n+(d3+d4)÷2)×π.

[0017] According to some embodiments of the utility model, the positive electrode ear and the negative electrode ear are connected at the outermost circle position of the wound battery cell, and the multiple transition zones are divided into a first transition zone, a second transition zone, a third transition zone and up to an nth transition zone along the head to tail direction of the positive electrode body and along the length direction of the positive electrode sheet. The thickness of the first transition zone is R1, the thickness of the second transition zone is R2, the thickness of the third transition zone is R3, the thickness of the nth transition zone is Rn, the thickness of the positive electrode sheet is d1, the thickness of the negative electrode sheet is d2, and the thickness of the separator is d3, then: R1=(d1+d2+2d3)×π, R2=(d1+d2+2d3)×2×π, R3=(d1+d2+2d3)×3×π, Rn=(d1+d2+2d3)×n×π.

[0018] According to some embodiments of the utility model, the positive electrode coating area is provided on the positive electrode main body at the inner circle of the wound battery cell and at the flat area, and the positive electrode coating area is provided on the positive electrode main body at the outer circle of the wound battery cell.

[0019] A battery according to an embodiment of the utility model includes:

[0020] The wound battery cell;

[0021] Electrolyte;

[0022] A shell is provided with a cavity in the shell, and the wound battery core and the electrolyte are both arranged in the cavity.

[0023] The battery according to the embodiment of the utility model has at least the following beneficial effects:

[0024] The positive electrode sheet, separator and negative electrode sheet are wound to form a wound battery cell. The positive electrode sheet is located in the inner circle of the wound battery cell and there is no dressing (no positive electrode coating) at the position inside the corner area, so that the CB value of the outer side of the negative electrode sheet in the corner area is sufficient, which can limit the number of lithium ions on the inner side of the positive electrode sheet in the corner area, thereby avoiding the situation of uneven distribution of lithium ions in the corner area, that is, there will be no situation where there are no vacant lithium insertion sites on the negative electrode sheet due to excessive lithium ions locally, thereby improving the problem of lithium precipitation of the negative electrode in the corner area of ​​the wound battery cell. Multiple transition zones and multiple positive electrode coating zones are arranged in an alternating manner, and the positive electrode main body is partially coated. After the wound battery cell expands in a cycle, the expansion stress can be released in the uncoated area (transition zone), which can improve deformation and enhance cycle performance.

[0025] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will become apparent from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention is further described below with reference to the accompanying drawings and embodiments, wherein:

[0027] Figure 1 This is a schematic structural diagram of a first wound battery cell according to an embodiment of the utility model;

[0028] Figure 2 A cross-sectional view of a first positive electrode sheet of a first wound battery cell according to an embodiment of the utility model;

[0029] Figure 3 A cross-sectional view of a second positive electrode sheet of a first wound battery cell according to an embodiment of the utility model;

[0030] Figure 4 A cross-sectional view of a negative electrode sheet of a first wound battery cell according to an embodiment of the utility model;

[0031] Figure 5 This is a schematic structural diagram of a second wound battery cell according to an embodiment of the utility model;

[0032] Figure 6 A cross-sectional view of a first positive electrode sheet of a second wound battery cell according to an embodiment of the utility model;

[0033] Figure 7 A cross-sectional view of a second positive electrode sheet of a second wound battery cell according to an embodiment of the utility model;

[0034] Figure 8 It is a cross-sectional view of the negative electrode sheet of the second wound battery cell according to an embodiment of the utility model.

[0035] Figure Number:

[0036] 100, negative electrode sheet; 110, negative electrode main body; 111, negative electrode coating area; 112, tab connection area; 120, negative electrode coating; 130, negative tab;

[0037] 200, positive electrode sheet; 210, positive electrode main body; 211, transition zone; 212, positive electrode coating zone; 220, positive electrode coating; 230, positive electrode ear;

[0038] 300, diaphragm;

[0039] A. Flat area; B. Corner area;

[0040] a. The length of the positive electrode coating area of ​​the inner circle of the wound battery; b. The width of the wound battery; c. The thickness of the wound battery; a1. The length of the positive electrode coating area of ​​the outer circle of the wound battery;

[0041] R0, the length of the positive electrode body connected to the positive electrode ear when the positive electrode ear is arranged in the innermost circle of the wound battery cell;

[0042] R1, the length of the first transition zone; R2, the length of the second transition zone; R3, the length of the third transition zone; Rn, the length of the nth transition zone;

[0043] Rm, the length of the positive electrode main body used for the outermost circle packaging of the wound battery cell (the sum of the length used to connect with the positive electrode ear when the positive electrode ear is arranged at the outermost circle of the wound battery cell and the length used for the outermost circle packaging of the wound battery cell). DETAILED DESCRIPTION

[0044] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0045] In the description of the present utility model, it is necessary to understand that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, unless otherwise specified, "multiple" means two or more.

[0046] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] See also Figure 1 , Figure 2 and Figure 3 The wound cell and battery of the embodiment of the utility model include a negative electrode sheet 100, a positive electrode sheet 200 and a separator 300. The positive electrode sheet 200 includes a positive electrode main body 210 and a positive electrode coating 220. The positive electrode main body 210 is provided with a plurality of transition regions 211 and a plurality of positive electrode coating regions 212 along the length direction of the positive electrode sheet 200. The plurality of transition regions 211 and the plurality of positive electrode coating regions 212 are arranged in an alternating manner. The positive electrode main body 210 is provided with a positive electrode coating 220 on both sides of the positive electrode coating region 212 and along the thickness direction of the positive electrode sheet 200. The separator 300 is provided between the negative electrode sheet 100 and the positive electrode sheet 200, and the separator 300 is used to separate the positive electrode sheet 200 from the negative electrode sheet 100. The negative electrode sheet 100, the separator 300 and the positive electrode sheet 200 are wound to form a wound cell. The wound cell includes a flat area and two corner areas, which are located on both sides of the flat area along the width direction of the wound cell. In the corner area of ​​the inner circle of the wound cell, the positive electrode main body 210 is not provided with a positive electrode coating 220 on the inner side of the transition area 211.

[0048] The positive electrode sheet 200, the separator 300 and the negative electrode sheet 100 are wound to form a wound battery cell. The positive electrode sheet 200 is located in the inner circle of the wound battery cell and there is no dressing (no positive electrode coating 220) at the position inside the corner area, so that the CB value of the outer side of the negative electrode sheet 100 in the corner area is sufficient, which can limit the number of lithium ions on the inner side of the positive electrode sheet 200 in the corner area, thereby avoiding the situation of uneven distribution of lithium ions in the corner area, that is, there will be no situation where there is no vacant lithium insertion position on the negative electrode sheet 100 due to excessive lithium ions locally, thereby improving the problem of lithium precipitation of the negative electrode in the corner area of ​​the wound battery cell. Multiple transition areas 211 and multiple positive electrode coating areas 212 are arranged in an alternating manner, and the positive electrode main body 210 is coated in sections. After the wound battery cell is cyclically expanded, the expansion stress can be released in the uncoated area (transition area 211), which can improve deformation and enhance cycle performance.

[0049] In some embodiments, see Figure 1 , Figure 2 and Figure 3In the corner area of ​​the inner circle of the wound battery cell, a positive electrode coating 220 is provided on the positive electrode main body 210 on the outer side of the transition area 211. On the premise of ensuring that there is no dressing on the inner side of the corner area, it is easier to coat the positive electrode coating 220 on the outer side of the transition area 211 on the positive electrode main body 210, which is simple to operate and saves work time.

[0050] In some embodiments, see Figure 1 , Figure 2 and Figure 3 In the corner area of ​​the inner circle of the wound battery cell, the positive electrode main body 210 is not provided with a positive electrode coating 220 on the outer side of the transition area 211. The positive electrode coating 220 is not provided on both sides of the transition area 211, and the amount of positive electrode coating 220 can be saved while ensuring that there is no dressing at the inner side of the corner area.

[0051] In some embodiments, see Figure 1 , Figure 2 and Figure 3 The lengths of the multiple positive electrode coating regions 212 located in the inner circle of the wound battery cell are consistent. The lengths of the multiple positive electrode coating regions 212 are consistent, which is convenient for implementation.

[0052] In some embodiments, see Figure 1 , Figure 2 and Figure 3 , the length of the multiple positive electrode coating areas 212 located in the inner circle of the wound battery cell is a, the width of the wound battery cell is b, and the thickness of the wound battery cell is c, then a=bc. The two corner areas of the wound battery cell are similar to two semicircles, the thickness of the wound battery cell is the diameter of the semicircle of the corner area, the thickness of the wound battery cell is the radius of the semicircle of the corner area and the length of the corner area, and the width of the wound battery cell is the sum of the length of the flat area and the length of the two corner areas. The lengths of the multiple positive electrode coating areas 212 are consistent, which is convenient for implementation.

[0053] In some embodiments, see Figure 1 , Figure 2 and Figure 3 The wound cell further includes a negative electrode ear 130 and a positive electrode ear 230, and the negative electrode ear 130 is connected to the negative electrode sheet 100. The positive electrode ear 230 is connected to the positive electrode main body 210, and the positive electrode coating 220 is not provided on both sides of the connection between the positive electrode main body 210 and the positive electrode ear 230 along the thickness direction of the positive electrode sheet 200. The positive electrode coating 220 is not provided on both sides of the connection between the positive electrode main body 210 and the positive electrode ear 230 along the thickness direction of the positive electrode sheet 200, so that the positive electrode ear 230 is conveniently connected to the positive electrode main body 210, and the electrical conduction between the positive electrode ear 230 and the positive electrode main body 210 is ensured.

[0054] In some embodiments, see Figure 1 , Figure 2 , Figure 3 and Figure 4 The positive electrode ear 230 and the negative electrode ear 130 are connected at the innermost circle of the wound battery cell. The multiple transition zones 211 are divided into the first transition zone, the second transition zone, the third transition zone and the nth transition zone along the head to tail direction of the positive electrode body 210 and along the length direction of the positive electrode sheet 200. The thickness of the first transition zone is R1, the thickness of the second transition zone is R2, the thickness of the third transition zone is R3, the thickness of the nth transition zone is Rn, the thickness of the positive electrode sheet 200 is d1, and the thickness of the negative electrode sheet 100 is d2, the thickness of the separator 300 is d3, the thickness of the positive electrode ear 230 is d4, and the thickness of the negative electrode ear 130 is d5, then: R1 = ((d1 + d2 + 2d3) + (d3 + d4) ÷ 2) × π, R2 = ((d1 + d2 + 2d3) × 2 + (d3 + d4) ÷ 2) × π, R3 = ((d1 + d2 + 2d3) × 3 + (d3 + d4) ÷ 2) × π, Rn = ((d1 + d2 + 2d3) × n + (d3 + d4) ÷ 2) × π. The lengths of the multiple transition zones 211 can be calculated, and the lengths of the multiple transition zones 211 are relatively accurate and convenient to implement (it can be segmented coating, or the positive electrode coating 220 can be scraped off after coating to expose the positive electrode body 210 to form the transition zone 211).

[0055] In some embodiments, see Figure 5 , Figure 6 , Figure 7 and Figure 8 The positive electrode ear 230 and the negative electrode ear 130 are connected at the outermost circle of the wound battery cell. The multiple transition zones 211 are divided into the first transition zone, the second transition zone, the third transition zone and the nth transition zone along the head to tail direction of the positive electrode body 210 and along the length direction of the positive electrode sheet 200. The thickness of the first transition zone is R1, the thickness of the second transition zone is R2, the thickness of the third transition zone is R3, the thickness of the nth transition zone is Rn, the thickness of the positive electrode sheet 200 is d1, the thickness of the negative electrode sheet 100 is d2, and the thickness of the separator 300 is d3. Then: R1=(d1+d2+2d3)×π, R2=(d1+d2+2d3)×2×π, R3=(d1+d2+2d3)×3×π, Rn=(d1+d2+2d3)×n×π. The lengths of the multiple transition zones 211 can be calculated, and the lengths of the multiple transition zones 211 are relatively accurate and easy to implement (it can be applied in sections, or the positive electrode coating 220 can be scraped off after coating to expose the positive electrode body 210 to form the transition zone 211).

[0056] In some embodiments, see Figure 1 , Figure 2 and Figure 3, a transition zone 211 is provided on the positive electrode main body 210 at a position located in the inner circle of the wound cell and at the corner area. A positive electrode coating area 212 is provided on the positive electrode main body 210 at a position located in the inner circle of the wound cell and at the flat area, and a positive electrode coating area 212 is provided on the positive electrode main body 210 at a position located in the outer circle of the wound cell. In the inner circle of the wound cell, the positive electrode coating area 212 is located on the flat area, and the length of the positive electrode coating area 212 on the positive electrode main body 210 is consistent, so it is more convenient to apply the positive electrode coating 220 on the positive electrode main body 210. In the outer circle of the wound cell, the positive electrode coating area 212 on the positive electrode main body 210 is longer, and there is no transition zone 211 in the middle, so it is more convenient to apply the positive electrode coating 220 on the positive electrode main body 210.

[0057] In some embodiments, see Figure 1 , Figure 4 , Figure 5 and Figure 8 The negative electrode sheet 100 includes a negative electrode main body 110 and a negative electrode coating 120. The negative electrode main body 110 is provided with a tab connection area 112 and a negative electrode coating area 111. The negative electrode main body 110 is located in the tab connection area 112 and is not provided with the negative electrode coating 120 on both sides along the thickness direction of the negative electrode sheet 100. The negative electrode main body 110 is located in the tab connection area 112 for connecting the negative tab 130. The negative electrode main body 110 is located in the negative electrode coating area 111 and is provided with the negative electrode coating 120 on both sides along the thickness direction of the negative electrode sheet 100.

[0058] A battery according to an embodiment of the utility model comprises a wound battery cell, an electrolyte and a shell, wherein a cavity is arranged in the shell, and the wound battery cell and the electrolyte are both arranged in the cavity.

[0059] The positive electrode sheet 200, the separator 300 and the negative electrode sheet 100 are wound to form a wound battery cell. The positive electrode sheet 200 is located in the inner circle of the wound battery cell and there is no dressing (no positive electrode coating 220) at the position inside the corner area, so that the CB value of the outer side of the negative electrode sheet 100 in the corner area is sufficient, which can limit the number of lithium ions on the inner side of the positive electrode sheet 200 in the corner area, thereby avoiding the situation of uneven distribution of lithium ions in the corner area, that is, there will be no situation where there is no vacant lithium insertion position on the negative electrode sheet 100 due to excessive lithium ions locally, thereby improving the problem of lithium precipitation of the negative electrode in the corner area of ​​the wound battery cell. Multiple transition areas 211 and multiple positive electrode coating areas 212 are arranged in an alternating manner, and the positive electrode main body 210 is coated in sections. After the wound battery cell is cyclically expanded, the expansion stress can be released in the uncoated area (transition area 211), which can improve deformation and enhance cycle performance.

[0060] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0061] Although the embodiments of the present invention have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A wound battery cell, characterized in that: include: Negative electrode; A positive electrode sheet, comprising a positive electrode main body and a positive electrode coating, wherein the positive electrode main body is provided with a plurality of transition zones and a plurality of positive electrode coating zones along the length direction of the positive electrode sheet, the plurality of transition zones and the plurality of positive electrode coating zones are arranged alternately, and the positive electrode coating is provided on both sides of the positive electrode main body located in the positive electrode coating zone and along the thickness direction of the positive electrode sheet; A separator, disposed between the negative electrode sheet and the positive electrode sheet; Among them, the wound battery cell includes a flat area and two corner areas, and the two corner areas are respectively located on both sides of the flat area along the width direction of the wound battery cell; in the corner area of ​​the inner circle of the wound battery cell, the positive electrode coating is not provided on the inner side of the transition zone on the positive electrode main body.

2. The wound battery cell according to claim 1, characterized in that: The positive electrode coating is provided on the positive electrode main body at the outer side of the transition zone in the corner area of ​​the inner circle of the wound battery cell.

3. The wound battery cell according to claim 1, characterized in that: In the corner area of ​​the inner circle of the wound battery cell, the positive electrode coating is not provided on the positive electrode main body portion located outside the transition area.

4. The wound battery cell according to claim 1, characterized in that: The lengths of the plurality of positive electrode coating areas located in the inner circle of the wound battery core are consistent.

5. The wound battery cell according to claim 4, characterized in that: The length of the plurality of positive electrode coating areas located in the inner circle of the wound battery core is a, the width of the wound battery core is b, and the thickness of the wound battery core is c, then a=bc.

6. The wound battery cell according to claim 1, characterized in that: It also includes a negative electrode ear and a positive electrode ear, wherein the negative electrode ear is connected to the negative electrode sheet, and the positive electrode ear is connected to the positive electrode main body, and the positive electrode coating is not provided on both sides of the connection between the positive electrode main body and the positive electrode ear along the thickness direction of the positive electrode sheet.

7. The wound battery cell according to claim 6, characterized in that: The positive electrode ear and the negative electrode ear are connected to the innermost circle position of the wound battery cell, and the multiple transition zones are divided into a first transition zone, a second transition zone, a third transition zone and an nth transition zone along the direction from the head to the tail of the positive electrode body and along the length direction of the positive electrode sheet. The thickness of the first transition zone is R1, the thickness of the second transition zone is R2, the thickness of the third transition zone is R3, the thickness of the nth transition zone is Rn, the thickness of the positive electrode sheet is d1, and the thickness of the negative electrode sheet is The thickness is d2, the thickness of the separator is d3, the thickness of the positive electrode ear is d4, and the thickness of the negative electrode ear is d5, then: R1 = ((d1+d2+2d3)+(d3+d4)÷2)×π, R2 = ((d1+d2+2d3)×2+(d3+d4)÷2)×π, R3 = ((d1+d2+2d3)×3+(d3+d4)÷2)×π, Rn = ((d1+d2+2d3)×n+(d3+d4)÷2)×π.

8. The wound battery cell according to claim 6, characterized in that: The positive electrode ear and the negative electrode ear are connected at the outermost circle position of the wound battery cell. The multiple transition zones are divided into a first transition zone, a second transition zone, a third transition zone and an nth transition zone along the direction from the head to the tail of the positive electrode body and along the length direction of the positive electrode sheet. The thickness of the first transition zone is R1, the thickness of the second transition zone is R2, the length of the third transition zone is R3, the thickness of the nth transition zone is Rn, the thickness of the positive electrode sheet is d1, the thickness of the negative electrode sheet is d2, and the thickness of the separator is d3. Then: R1=(d1+d2+2d3)×π, R2=(d1+d2+2d3)×2×π, R3=(d1+d2+2d3)×3×π, Rn=(d1+d2+2d3)×n×π.

9. The wound battery cell according to claim 1, characterized in that: The positive electrode coating area is provided on the positive electrode main body at the inner circle of the wound battery cell and at the flattened area, and the positive electrode coating area is provided on the positive electrode main body at the outer circle of the wound battery cell.

10. A battery, characterized in that: include: The wound battery cell according to any one of claims 1 to 9; Electrolyte; A shell is provided with a cavity in the shell, and the wound battery core and the electrolyte are both arranged in the cavity.

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