Pole piece and battery

Abstract

The utility model discloses a pole piece and a battery. The pole piece comprises a current collector and a coating part arranged on the side surface of the current collector, the current collector comprises a coating area and an empty foil area which are connected in sequence, and the coating part is located in the coating area; the coating part comprises a first active material layer and a second active material layer which are stacked, and the first active material layer is located between the current collector and the second active material layer; in the first direction, the distance from the end, close to the empty foil area, of the first active material layer to the end, close to the empty foil area, of the second active material layer is S3, and S3 is smaller than or equal to 1 mm. Therefore, the current collector in the pole piece is coated with the double active material layers, the distance S3 from the end part, close to the empty foil region, of the first active substance layer to the end part, close to the empty foil region, of the second active substance layer is smaller than or equal to 1mm, the alignment degree of the two active substance layers is relatively high, the overall thickness of the pole piece is relatively balanced, and the uniform thickness of the pole piece is beneficial to improving the stability of the battery.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a pole piece, and also to a battery with the pole piece. Background Art

[0002] With people's growing demand, lithium-ion batteries have become the main power source for consumer electronics and electric vehicles. They have the advantages of high energy density and power density, high operating voltage, light weight, small size, long cycle life, good safety, and green environmental protection. They have broad application prospects in portable appliances, power tools, large-scale energy storage, and electric transportation power sources.

[0003] However, the existing battery structure has problems such as low safety and stability, as well as a high risk of lithium plating. Utility Model Content

[0004] In view of this, an object of the present invention is to provide a pole piece to improve the safety and stability of the battery.

[0005] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0006] A pole piece, comprising a current collector and a coating portion arranged on a side surface of the current collector;

[0007] The current collector comprises a coating area and a hollow foil area connected in sequence, and the coating portion is located in the coating area;

[0008] The coating portion includes a first active material layer and a second active material layer stacked together, wherein the first active material layer is located between the current collector and the second active material layer;

[0009] Wherein, along the first direction, the distance between the end of the first active material layer close to the empty foil area and the end of the second active material layer close to the empty foil area is S3, |S3|≤1mm.

[0010] Optionally, in the above-mentioned pole piece, the coating portion includes a first area close to the empty foil area and a second area away from the empty foil area;

[0011] Along the first direction, the size of the first region is S1, |S3|>0, |S3 / S1|≤0.33.

[0012] Optionally, in the above-mentioned pole piece,

[0013] S3>0, the first region of the second active material layer includes a first area in contact with the first active material layer and a second area in contact with the empty foil area; the ratio of the thickness of the second active material layer at the junction of the first area and the second area to the overall thickness of the first active material layer and the second active material layer in the second region is 0.90~1.05.

[0014] Alternatively, S3<0, the first region of the first active material layer includes a third region in contact with the second active material layer and a fourth region not in contact with the second active material layer; the ratio of the thickness of the first active material layer at the junction of the third region and the fourth region to the overall thickness of the first active material layer and the second active material layer in the second region is 0.90~1.05.

[0015] Optionally, in the above-mentioned pole piece, the thickness of the pole piece in the second region is T;

[0016] Along the first direction, the free end of the first region includes a trough protruding from the inside to the outside, and the thickness of the pole piece in the region where the distance from the trough is greater than 2.5 mm is T±2 μm.

[0017] A battery comprises a first pole sheet and a second pole sheet which are stacked and wound to form a winding core, wherein at least the first pole sheet of the first pole sheet and the second pole sheet is the above-mentioned pole sheet, and the first pole sheet is located at the innermost side of the winding.

[0018] Optionally, in the above battery, along the first direction, a distance between an end of the coated area in the second pole piece close to the empty foil area and an end of the coated area in the first pole piece close to the empty foil area is D, and D>2mm.

[0019] Optionally, in the above battery, along the first direction, the first pole sheet includes a double-sided region with the coating portion provided on both sides of the current collector, and a single-sided region with the coating portion provided on one side of the current collector.

[0020] Optionally, in the above battery, the double-sided region includes a first coating portion and a second coating portion located on both sides of the current collector;

[0021] Wherein, the distance between the end of the first coating portion away from the single-sided area and the end of the second coating portion away from the single-sided area is C1, and C1≤0.5mm;

[0022] And / or, the first coating portion and the second coating portion are away from the ends of the single-sided area, and the distance from the end farthest from the single-sided area of ​​either the first coating portion or the second coating portion to the end of the first active material layer and the second active material layer in the other that is closest to the single-sided area is C2, and C2≤1.5mm.

[0023] Optionally, in the above battery, the first pole piece includes a straight segment and an arc segment arranged in sequence,

[0024] Wherein, the end of the coating area in the single-sided area of ​​the first pole piece close to the empty foil area is located in the arc section on the inner side of the winding;

[0025] Alternatively, the coated area in the single-sided area of ​​the first pole piece is located in the straight section near the end of the empty foil area.

[0026] Optionally, in the above-mentioned battery, the arc segment where the end of the coated area in the double-sided area close to the empty foil area is located is a first arc segment, and the first arc segment is located outside the arc segment where the end of the coated area in the single-sided area of ​​the first pole piece close to the empty foil area is located.

[0027] Optionally, in the above battery, projections of an end of the coated area in the double-sided area close to the empty foil area and an end of the coated area in the single-sided area of ​​the first pole piece close to the empty foil area in the second direction at least partially overlap.

[0028] Optionally, in the above battery,

[0029] The end point of the coating area in the single-sided area close to the empty foil area does not exceed the intersection point between the arc segment and the straight segment away from the coating area;

[0030] And / or, the coated area in the single-sided area is closer to the end point of the hollow foil area than half the length of the circular arc segment.

[0031] Optionally, in the above battery, the single-sided area of ​​the first pole piece is located at the innermost side of the winding, D=S1±0.5m.

[0032] Optionally, in the above battery, the arc length between the end of the coated area in the second pole piece close to the empty foil area and the end of the double-sided area in the first pole piece close to the empty foil area is G, and G≥D.

[0033] It can be seen from the above technical solution that one side of the current collector in the pole piece provided by the utility model is provided with a coating part, and the coating part includes a first active material layer and a second active material layer, that is, a double-layer active material layer is coated on the current collector, and along the first direction, the distance from the end of the first active material layer close to the empty foil area to the end of the second active material layer close to the empty foil area is S3, |S3|≤1mm, the alignment degree of the two layers of active materials is relatively high, the overall thickness of the pole piece is relatively balanced, and the uniform pole piece thickness helps to improve the safety and stability of the battery. And when the pole piece is used for the negative electrode, it can reduce the risk of lithium deposition in lithium batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 A schematic diagram of the structure of the winding core unwinding the pole piece winding head provided in an embodiment of the utility model;

[0036] Figure 2 A schematic diagram of the structure of the pole piece end provided by an embodiment of the utility model;

[0037] Figure 3a The utility model provides a schematic diagram of the structure of the pole piece end structure overlapped and misaligned Figure 1 ;

[0038] Figure 3b The utility model provides a schematic diagram of the structure of the pole piece end structure overlapped and misaligned Figure 2 ;

[0039] Figure 3c A third structural diagram of the overlapped and misaligned pole piece end structure is provided for an embodiment of the utility model;

[0040] Figure 4 Schematic diagram of the local structure of the paste coating head of the single-sided double-layer area of ​​the winding core unfolding pole piece provided by the embodiment of the utility model Figure 1 ;

[0041] Figure 5 Schematic diagram of the local structure of the paste coating head of the single-sided double-layer area of ​​the winding core unfolding pole piece provided by the embodiment of the utility model Figure 2 ;

[0042] Figure 6 Schematic diagram 3 of the partial structure of the paste coating head of the single-sided double-layer area of ​​the winding core unfolding pole piece provided by the embodiment of the utility model;

[0043] Figure 7 A schematic diagram of the corresponding relationship between the paste coating head of the double-sided double-layer area of ​​the first pole piece and the second pole piece in the winding core provided by the embodiment of the utility model Figure 1 ;

[0044] Figure 8 A schematic diagram of the corresponding relationship between the paste coating head of the double-sided double-layer area of ​​the first pole piece and the second pole piece in the winding core provided by the embodiment of the utility model Figure 2 ;

[0045] Fig. 9 A third structural diagram of the corresponding relationship between the paste coating head of the double-sided double-layer area of ​​the first pole piece and the second pole piece in the winding core provided by the embodiment of the utility model;

[0046] Fig.10 A schematic diagram of the double-sided tail overlapped staggered structure of the roll core unfolded according to the embodiment of the utility model;

[0047] Fig.11 The structure of the winding core provided by the embodiment of the utility model is schematically shown Figure 1 ;

[0048] Fig.12 The structure of the winding core provided by the embodiment of the utility model is schematically shown Figure 2 ;

[0049] Fig.13 A third structural diagram of a winding core provided in an embodiment of the utility model;

[0050] Fig.14 A schematic diagram of the uneven end of a pole piece provided in an embodiment of the utility model.

[0051] in:

[0052] 1-current collector, 11-coating area, 12-empty foil area, 121-trough,

[0053] 2-coating part, 21-first active material layer, 22-second active material layer,

[0054] 3-first pole piece, 4-second pole piece, 5-winding core, 51-straight section, 52-arc section. DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0056] In the description of the utility model, it should be noted that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the utility model product is usually placed when in use, and are only for the convenience of describing the 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 utility model. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0057] like Figures 1 to 14 As shown, an embodiment of the utility model provides a pole piece.

[0058] First, the pole piece includes a current collector and a coating portion arranged on the side surface of the current collector; the current collector includes a coating area and a hollow foil area connected in sequence, and the coating portion is located in the coating area; the coating portion includes a first active material layer and a second active material layer stacked, and the first active material layer is located between the current collector and the second active material layer (that is, the first active material layer is the bottom active material layer, and the second active material layer is the surface active material layer); wherein, along the first direction, the distance from the end of the first active material layer close to the hollow foil area to the end of the second active material layer close to the hollow foil area is S3, |S3|≤1mm, that is, S3 is between -1mm and +1mm, and S3 is positive, indicating that the end of the surface active material exceeds the end of the bottom active material, see for details Figure 3a ; S3 is zero, indicating that the end of the surface active material coincides with the end of the bottom active material, see Figure 3b , the projection of the surface active material in the second direction (i.e. the thickness direction of the electrode) is located inside the bottom active material. At this time, the surface active material layer and the bottom active material layer are flush with the end close to the empty foil area, which can more effectively utilize the space of the electrode and improve the energy density of the battery; S3 is negative, which means that the end of the bottom active material exceeds the end of the surface active material. For details, see Figure 3c It should be noted that the first direction is the direction in which the core is unfolded, see Figure 1 In the direction of the arrow in the figure. In addition, the first active material layer is a high-density (high energy density) active material and the second active material layer is a high-charge rate (high rate) active material. When the electrode is a negative electrode, the capacity of the lithium battery is ensured by the high-density first active material layer, and the fast charging performance of the battery is ensured by the high-rate second active material layer, so as to achieve the purpose of reducing lithium plating and improving the volume energy density of the battery cell.

[0059] It can be seen that the pole piece provided by the embodiment of the utility model has a coating portion on one side of the current collector, and the coating portion includes a first active material layer and a second active material layer, that is, a double-layer active material layer is coated on the current collector, and along the first direction, the distance from the end of the first active material layer close to the empty foil area to the end of the second active material layer close to the empty foil area is S3, |S3|≤1mm, the alignment degree of the two layers of active material is relatively high, the overall thickness of the pole piece is relatively balanced, and the uniform pole piece thickness helps to improve the safety and stability of the battery. And when the pole piece is used for the negative electrode, it can reduce the risk of lithium deposition in lithium batteries.

[0060] In a specific implementation, the coating portion includes a first area close to the empty foil area and a second area away from the empty foil area, and the thickness of the first area is less than the thickness of the second area; along the first direction, the size of the first area is S1, |S3|>0, |S3 / S1|≤0.33. |S3 / S1| can be any one of 0.1, 0.2, 0.3, etc. The smaller the ratio of |S3 / S1|, the shorter the first area of ​​the pole piece or the higher the alignment of the two layers of active material, the more balanced the overall thickness of the pole piece, and the uniform pole piece thickness helps to improve the safety and stability of the battery. Uniformity can ensure the consistency of battery performance during the charge and discharge cycle.

[0061] For specific implementation, see Figure 3a , S3>0, the first region of the second active material layer includes a first region in contact with the first active material layer and a second region in contact with the empty foil region; the ratio of the thickness of the second active material layer at the junction of the first region and the second region to the overall thickness of the first active material layer and the second active material layer in the second region is 0.90~1.05, which can ensure the uniformity of the overall thickness of the electrode sheet, and the uniform electrode sheet thickness helps to improve the stability of the battery.

[0062] Alternatively, see Figure 3c , S3<0, the first region of the first active material layer includes the third region in contact with the second active material layer and the fourth region not in contact with the second active material layer; the ratio of the thickness of the first active material layer at the junction of the third region and the fourth region to the overall thickness of the first active material layer and the second active material layer in the second region is 0.90~1.05, which can ensure the uniformity of the overall thickness of the electrode sheet, and the uniform electrode sheet thickness helps to improve the stability of the battery.

[0063] See Fig.14In a specific implementation, the thickness of the pole piece in the second region is T; along the first direction, the free end of the first region includes a trough protruding from the inside to the outside, and the thickness of the pole piece in the region where the distance from the trough is greater than 2.5mm is T±2μm (i.e., the range of the thickness of the pole piece is ≤4μm). It can ensure that there is no risk of lithium deposition at the second pole piece that has a corresponding position relationship with the first pole piece, and the electrode with uniform thickness can achieve a more uniform charge distribution. It helps to avoid local overcharging or discharging in the battery, reduce uneven aging of the battery, and thus extend the battery life.

[0064] An embodiment of the utility model provides a battery, comprising a first pole piece and a second pole piece stacked and wound to form a winding core, wherein at least the first pole piece of the first pole piece and the second pole piece is the above-mentioned pole piece, and the first pole piece is located at the innermost side of the winding.

[0065] It can be seen that in the battery provided by the embodiment of the utility model, one side of the current collector in the pole piece is provided with a coating part, and the coating part includes a first active material layer and a second active material layer, that is, a double-layer active material layer is coated on the current collector, and along the first direction, the distance from the end of the first active material layer close to the empty foil area to the end of the second active material layer close to the empty foil area is S3, |S3|≤1mm, the alignment degree of the two layers of active material is relatively high, the overall thickness of the pole piece is relatively balanced, and the uniform pole piece thickness helps to improve the stability of the battery. And when the pole piece is used for the negative electrode, it can reduce the risk of lithium deposition in the lithium battery.

[0066] In specific implementation, along the first direction, the distance between the end of the coated area in the second pole piece close to the empty foil area and the end of the coated area in the first pole piece close to the empty foil area is D, and D>2mm. It should be noted that the first pole piece and the second pole piece have opposite polarities. Taking the first pole piece as the negative pole piece as an example, after the winding core is unfolded, the projection of the coated area of ​​the innermost first pole piece along the second direction (i.e., the thickness direction of the pole piece) covers the projection of the second pole piece along the second direction. It can avoid lithium deposition in the battery, and at the same time, the thickness of the battery cell can be made relatively small during the winding process in the winding core, which can increase the volume energy density of the battery cell.

[0067] In a specific implementation, along the first direction, the first pole piece includes a double-sided area where the coating part is provided on both sides of the current collector, and a single-sided area where the coating part is provided on one side of the current collector.

[0068] For specific implementation, see Fig.10, the double-sided area includes a first coating part and a second coating part located on both sides of the current collector; wherein, the end of the first coating part away from the single-sided area (the end of the first coating part close to the single-sided area is the head, and the end of the first coating part away from the single-sided area is the tail), and the end of the second coating part away from the single-sided area (the end of the second coating part close to the single-sided area is the head, and the end of the second coating part away from the single-sided area is the tail) is C1, C1≤0.5mm; and / or, the end of the first coating part and the second coating part away from the single-sided area, the end of either the first coating part and the second coating part farthest from the single-sided area, to the end of the first active material layer and the second active material layer in the other closest to the single-sided area is C2, C2≤1.5mm. That is, the alignment degree of the pole piece at the tail of the current collector in the double-sided area is high, which can ensure the consistency of the internal structure of the battery and help improve the stability and safety of the battery.

[0069] For specific implementation, see Figure 11-13 , the first pole piece includes a straight section and an arc section arranged in sequence, wherein the end of the coated area in the single-sided area of ​​the first pole piece close to the empty foil area is located in the innermost arc section of the winding; or the end of the coated area in the single-sided area of ​​the first pole piece close to the empty foil area is located in the straight section, see Figure 11-13 .

[0070] In specific implementation, the arc segment where the end of the coated area in the double-sided area close to the empty foil area is located is the first arc segment, and the first arc segment is located outside the arc segment where the end of the coated area in the single-sided area of ​​the first pole piece close to the empty foil area is located.

[0071] In a specific implementation, the projections of the end of the coated area in the double-sided area close to the empty foil area and the end of the coated area in the single-sided area of ​​the first pole piece close to the empty foil area in the second direction at least partially overlap.

[0072] For specific implementation, see Fig.11 , Fig.13 , the end point of the coated area in the single-sided area close to the empty foil area does not exceed the intersection point between the arc segment and the straight segment away from the coated area; and / or, the end point of the coated area in the single-sided area close to the empty foil area exceeds half the length of the arc segment. The stability of the battery can be improved. To a certain extent, the battery can maintain more stable performance during multiple charge and discharge cycles, reducing the rapid decline of battery capacity and power.

[0073] In specific implementation, the single-sided area of ​​the first pole piece is located at the innermost side of the winding, D = S1 ± 0.5m. It is ensured that the negative electrode in the first direction of the battery can cover the positive electrode to form a covering area. The value of D makes the covering area as small as possible, which not only helps to improve the heat dissipation performance of the battery, but also can improve the surface area to volume ratio of the battery, which helps to dissipate the generated heat more effectively.

[0074] For specific implementation, see Figure 7-Figure 9, the arc length between the end of the coated area in the second pole piece close to the empty foil area and the end of the double-sided area in the first pole piece close to the empty foil area is G, G≥D. It should be noted that, taking the first pole piece as the negative pole piece as an example, along the thickness direction of the winding core, the projection of the end of the double-sided area of ​​the first pole piece close to the single-sided area covers the projection of the end of the coated area of ​​the second pole piece close to the uncoated area. That is, the first pole piece covers the second pole piece, which is beneficial to improving the performance of the battery. It can ensure better contact between the positive and negative electrodes, reduce resistance, and promote more effective charge transfer, thereby improving the battery's energy conversion efficiency. In addition, since the arc length of the innermost arc segment of the first arc segment is longer, G≥D, the end of the double-sided area close to the single-sided area (i.e., the head of the double-sided area) does not exceed the arc segment, ensuring that the head of the double-sided area is bent inside the arc segment and has a coating portion, and the thickness of the winding core in the radial direction of the arc segment is as consistent as possible, avoiding the occurrence of hollow drum areas that cause insufficient contact between the positive and negative active materials of the battery and increase the impedance of the battery.

[0075] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0076] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0077] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A pole piece, characterized in that: It comprises a current collector (1) and a coating portion (2) arranged on a side surface of the current collector (1); The current collector (1) comprises a coating area (11) and a hollow foil area (12) which are connected in sequence, and the coating portion (2) is located in the coating area (11); The coating portion (2) comprises a first active material layer (21) and a second active material layer (22) which are stacked, wherein the first active material layer (21) is located between the current collector (1) and the second active material layer (22); Wherein, along the first direction, the distance between the end of the first active material layer (21) close to the empty foil area (12) and the end of the second active material layer (22) close to the empty foil area (12) is S3, | S3 | ≤1mm.

2. The pole piece according to claim 1, characterized in that: The coating portion (2) comprises a first region close to the empty foil region (12) and a second region facing away from the empty foil region (12); Along the first direction, the size of the first region is S1, |S3|>0, |S3 / S1|≤0.

33.

3. The pole piece according to claim 2, characterized in that: S3>0, the first region of the second active material layer (22) includes a first region in contact with the first active material layer (21) and a second region in contact with the empty foil region (12); the ratio of the thickness of the second active material layer (22) at the boundary between the first region and the second region to the overall thickness of the first active material layer (21) and the second active material layer (22) in the second region is 0.90 to 1.05; Alternatively, S3<0, the first region of the first active material layer (21) includes a third region in contact with the second active material layer (22) and a fourth region not in contact with the second active material layer (22); the ratio of the thickness of the first active material layer (21) at the boundary between the third region and the fourth region to the overall thickness of the first active material layer (21) and the second active material layer (22) in the second region is 0.90 to 1.

05.

4. The pole piece according to claim 2, characterized in that: The thickness of the pole piece in the second region is T; Along the first direction, the free end of the first region comprises a trough (121) protruding from the inside to the outside, and the thickness of the pole piece in the region where the distance from the trough (121) is greater than 2.5 mm is T±2 μm.

5. A battery, characterized in that: The invention comprises a first pole piece (3) and a second pole piece (4) which are stacked and wound to form a winding core (5), wherein at least the first pole piece (3) of the first pole piece (3) and the second pole piece (4) is the pole piece described in any one of claims 1 to 4, and the first pole piece (3) is located at the innermost side of the winding.

6. The battery according to claim 5, characterized in that Along the first direction, the distance between the end of the coated area (11) in the second pole piece (4) close to the empty foil area (12) and the end of the coated area (11) in the first pole piece (3) close to the empty foil area (12) is D, and D>2mm.

7. The battery according to claim 5, characterized in that Along the first direction, the first pole piece (3) comprises a double-sided region in which the coating portion (2) is arranged on both sides of the current collector (1), and a single-sided region in which the coating portion (2) is arranged on one side of the current collector (1).

8. The battery according to claim 7, characterized in that The double-sided area comprises a first coating portion and a second coating portion located on both sides of the current collector (1); Wherein, the distance between the end of the first coating portion away from the single-sided area and the end of the second coating portion away from the single-sided area is C1, and C1≤0.5mm; And / or, the first coating portion and the second coating portion are away from the end of the single-sided area, and the distance from the end of either the first coating portion or the second coating portion farthest from the single-sided area to the end of the first active material layer (21) and the second active material layer (22) in the other that is closest to the single-sided area is C2, and C2≤1.5mm.

9. The battery according to claim 7, characterized in that The first pole piece (3) comprises a straight section (51) and an arc section (52) which are arranged in sequence; Wherein, the end of the coated area (11) in the single-sided area of ​​the first pole piece (3) close to the empty foil area (12) is located at the circular arc section (52) on the inner side of the winding; Alternatively, the coated area (11) in the single-sided area of ​​the first pole piece (3) is located in the straight section (51) at an end close to the empty foil area (12).

10. The battery according to claim 9, characterized in that The arc segment (52) where the end of the coated area (11) in the double-sided area close to the empty foil area (12) is located is a first arc segment, and the first arc segment is located outside the arc segment (52) where the end of the coated area (11) in the single-sided area of ​​the first pole piece (3) close to the empty foil area (12) is located.

11. The battery according to claim 9, characterized in that The projections of the end of the coated area (11) in the double-sided area close to the empty foil area (12) and the end of the coated area (11) in the single-sided area of ​​the first pole piece (3) close to the empty foil area (12) in the second direction at least partially overlap.

12. The battery according to claim 9, characterized in that The end point of the coating area (11) in the single-sided area close to the empty foil area (12) does not exceed the intersection point between the circular arc segment (52) and the straight segment (51) away from the coating area (11); And / or, the end point of the coated area (11) in the single-sided area close to the empty foil area (12) exceeds half of the length of the circular arc segment (52).

13. The battery according to claim 7, characterized in that The single-sided area of ​​the first pole piece (3) is located at the innermost side of the winding, D=S1±0.5m.

14. The battery according to claim 13, characterized in that The arc length between the end of the coated area (11) in the second pole piece (4) close to the empty foil area (12) and the end of the double-sided area in the first pole piece (3) close to the empty foil area (12) is G, and G≥D.

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