Pole piece, battery cell and battery

Abstract

The utility model discloses a pole piece, a battery cell and a battery, and relates to the technical field of new energy. The pole piece comprises a tab and a pole piece main body, the tab is connected with the pole piece main body, the pole piece main body is provided with a first edge and a second edge which are oppositely arranged along the width direction of the pole piece main body, and the tab extends out of the pole piece main body from the first edge; the pole piece is provided with a plurality of contour lines which are arranged in parallel at intervals, an arc-shaped notch is formed in a second edge between every two adjacent contour lines, and the distance from the edge of each arc-shaped notch to the first edge is gradually reduced and then gradually increased in the length direction of the pole piece. After the pole piece is wound, a battery cell with an arc-shaped bottom can be formed, so that the pole piece can be matched with the bottom shape of a battery shell, and the overall energy density of the battery cell can be further improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to new energy technology field especially, relate to a kind of pole piece, electric core and battery. BACKGROUND

[0002] In soft package battery manufacturing process, be influenced by the impact mould and packaging process, the bottom of battery shell can form the arc surface that recesses towards accommodating cavity, along the width direction of electric core, the distance of the bottom of battery shell and the top of battery shell is big on both sides, small in the middle phenomenon.

[0003] Therefore, after electric core is assembled into shell, the bottom of electric core and the bottom of battery shell can exist larger space, to cause the waste of space in shell, greatly affect the promotion of battery energy density. SUMMARY

[0004] The utility model at least solves one of the technical problems in prior art. To this end, the utility model provides a kind of pole piece, winding can form the electric core with arc-shaped bottom, so it can be adapted to the bottom shape of battery shell, so it can further improve the energy density of electric core as a whole.

[0005] The utility model further provides a kind of electric core with the above-mentioned pole piece.

[0006] The utility model further provides a kind of battery with the above-mentioned electric core.

[0007] According to the pole piece of the first aspect embodiment of the utility model, including tab and pole piece main body, the tab is connected with the pole piece main body, wherein:

[0008] The pole piece main body has first edge and second edge oppositely arranged along its width direction, and the tab is stretched out to the outside of the pole piece main body by the first edge;

[0009] The pole piece has a plurality of parallel and interval arranged contour lines, and the second edge between adjacent two contour lines is provided with arc-shaped notch, and the distance from the edge of the arc-shaped notch to the first edge gradually decreases and then gradually increases along the length direction of the pole piece.

[0010] According to the pole piece of the utility model embodiment, at least has following beneficial effects:

[0011] The electrode sheet of the application can form a battery cell with an arc-shaped bottom after winding, so as to adapt to the shape of the bottom of the battery shell. For the same battery shell, if a battery cell with a flat bottom in the prior art is used, the battery cell is affected by the deformation of the battery shell, and when the distance between the bottom of the battery cell and the middle part of the bottom of the shell reaches the minimum value required by the design, the distance between the bottom of the battery cell and the edge part of the bottom of the shell is still large, thereby wasting part of the space. The shape of the bottom of the battery cell formed by winding the electrode sheet of the application matches the shape of the bottom of the shell, and the width of the electrode sheet of the application is wider than that of the electrode sheet forming a common battery cell. After winding to form a battery cell, the length of the battery cell is longer than that of a common battery cell, so as to increase the content of active material inside the battery cell, thereby further improving the energy density of the battery cell as a whole. In addition, since the gap between the bottom of the battery cell and the battery shell is small, the risk of the battery shell being easily dented and deformed when subjected to external force impact can be reduced, and the problem of poor appearance of the battery cell can be improved.

[0012] According to some embodiments of the application, the second edge is arranged to be inclined compared to the first edge, the electrode sheet body has a winding start end and a winding end, and the second edge is configured to gradually reduce in distance to the first edge in a direction from the winding start end to the winding end.

[0013] According to some embodiments of the application, the electrode sheet body comprises a current collector and active material layers coated on both sides of the current collector, and the widths of the active material layers on both sides of the current collector are not equal.

[0014] According to the battery cell of the second aspect of the application, the electrode sheet has a winding start end and a winding end, and the electrode sheet is wound from the winding start end to the winding end to form the battery cell. The battery cell has a first end and a second end in the length direction thereof. The first end is formed by winding the first edge, and the second end is formed by winding the second edge.

[0015] In the projection in the thickness direction of the battery cell, the second end is configured to gradually decrease in distance to the first end in the width direction of the battery cell and then gradually increase in distance to the first end in the width direction of the battery cell.

[0016] According to some embodiments of the application, in the projection in the width direction of the battery cell, the second end is configured to gradually increase in distance to the first end in the thickness direction of the battery cell and then gradually decrease in distance to the first end in the thickness direction of the battery cell.

[0017] According to some embodiments of the application, the electrode sheet comprises positive electrode sheets and negative electrode sheets, and the positive electrode sheets and the negative electrode sheets are arranged alternately in the direction from the inside to the outside of the battery cell.

[0018] The positive electrode sheet comprises a positive electrode current collector, a first positive electrode active layer coated on the inner side of the positive electrode current collector, and a second positive electrode active layer coated on the outer side of the positive electrode current collector, and the dimension of the second positive electrode active layer along the length direction of the battery is smaller than the dimension of the first positive electrode active layer along the length direction of the battery at the second end.

[0019] According to some embodiments of the present application, the electrode sheet comprises a positive electrode sheet and a negative electrode sheet, and the positive electrode sheet and the negative electrode sheet are arranged alternately along the direction from the inside to the outside of the battery.

[0020] The negative electrode sheet comprises a negative electrode current collector, a first negative electrode active layer coated on the inner side of the negative electrode current collector, and a second negative electrode active layer coated on the outer side of the negative electrode current collector, and the dimension of the first negative electrode active layer along the length direction of the battery is greater than the dimension of the second negative electrode active layer along the length direction of the battery at the second end.

[0021] According to some embodiments of the present application, the electrode sheet comprises a positive electrode sheet and a negative electrode sheet, and the positive electrode sheet and the negative electrode sheet are arranged alternately along the direction from the inside to the outside of the battery.

[0022] Among any one positive electrode sheet and two adjacent negative electrode sheets, the positive electrode sheet comprises a positive electrode current collector, a first positive electrode active layer coated on the inner side of the positive electrode current collector, and a second positive electrode active layer coated on the outer side of the positive electrode current collector, and the negative electrode sheet comprises a negative electrode current collector and negative electrode active layers coated on both sides of the negative electrode current collector respectively, the length difference between the first positive electrode active layer and the adjacent negative electrode active layer is OH1, the length difference between the second positive electrode active layer and the adjacent negative electrode active layer is OH2, and OH1=OH2.

[0023] According to some embodiments of the present application, the electrode sheet comprises a positive electrode sheet, a negative electrode sheet and a separator, and the positive electrode sheet and the negative electrode sheet are arranged alternately along the direction from the inside to the outside of the battery, and the positive electrode sheet and the adjacent negative electrode sheet are separated by the separator.

[0024] At the second end and along the length direction of the battery, the negative electrode sheet protrudes compared with the adjacent positive electrode sheet, and the separator protrudes compared with the adjacent negative electrode sheet.

[0025] The battery according to the third aspect of the present application comprises the battery cell mentioned in any one of the above embodiments.

[0026] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0027] The utility model will be further described below in combination with the drawings and embodiments, in which:

[0028] Figure 1 is the battery structure schematic drawing (observe along the thickness direction of the electric core) and the enlarged schematic drawing of A area in the prior art;

[0029] Figure 2 is the battery structure schematic drawing (observe along the width direction of the electric core) and the enlarged schematic drawing of B area in the prior art;

[0030] Figure 3 is the structure schematic drawing of the pole piece of the utility model;

[0031] Figure 4 is the structure schematic drawing of the battery of the utility model (observe along the thickness direction of the electric core) and the enlarged schematic drawing of C area;

[0032] Figure 5 is the partial enlarged schematic drawing of the electric core at the second end (observe along the width direction of the electric core);

[0033] Figure 6 is the partial enlarged schematic drawing of the electric core at the second end (observe along the width direction of the electric core);

[0034] Figure 7 is the partial enlarged schematic drawing of the electric core at the second end (observe along the width direction of the electric core).

[0035] Reference signs:

[0036] Pole piece 10; winding end 11; winding end 12;

[0037] Pole lug 100;

[0038] Pole piece main body 200; contour line 201; first edge 210; Second edge 220; Arc-shaped notch 221;

[0039] Electric core 30; First end 31; Second end 32;

[0040] Positive pole piece 300; Positive current collector 310; First positive active layer 320; Second positive active layer 330;

[0041] Negative pole piece 400; Negative current collector 410; First negative active layer 420; Second negative active layer 430;

[0042] Diaphragm 500;

[0043] Shell 60; Sealing area 61; DETAILED DESCRIPTION

[0044] The embodiments of the present application are described below in detail, examples of which are shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary only, and are for the purpose of explanation of the present application, and are not to be understood as a limitation of the present application.

[0045] In the description of the present application, it is understood that the orientation description, such as the orientation or position relationship indicated by up, down, front, back, left, right, etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0046] In the description of the present application, the meaning of several is more than one, the meaning of multiple is more than two, greater than, less than, more than, etc. are understood as not including the number, above, below, etc. are understood as including the number. If it is described as first, second, it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or the order of technical features indicated.

[0047] In the description of the present application, unless otherwise explicitly limited, the words such as setting, installing, connecting, etc. should be broadly understood, and the person skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical solution.

[0048] In the description of the present application, the description of the reference terms "one embodiment", "some embodiments", "illustrative embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the present application. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0049] In the soft package battery manufacturing process, affected by the punching die and the packaging process, the bottom of the battery shell 60 forms a concave arc surface facing the accommodation cavity, and along the width direction of the battery cell 30, the distance between the bottom of the battery shell 60 and the top of the battery shell 60 is larger on both sides and smaller in the middle.

[0050] More specifically, the shell 60 of the soft package battery is commonly made of aluminum plastic film material. Before being punched, the aluminum plastic film is cut to have consistent length at each position. During the punching, part of the aluminum plastic film is stretched in the thickness direction under pressure, and the size of the punched position is supplemented in the vertical direction, so the length is reduced. The length of the non-punched area remains unchanged. At the same time, the non-punched area is also the sealing area 61. The aluminum plastic film is stretched under heat and pressure, so the length is increased. As a result, the punched area is shortened due to stretching, and the non-punched area is lengthened due to heat and pressure stretching. The two form a deformation difference at the junction. To coordinate this difference, as shown in Figure 1 , the aluminum plastic film is forced to shrink inward at the bottom of the shell 60, thereby forming a concave arc surface toward the top.

[0051] As a result, as shown in the enlarged view of area A in Figure 1 , after the cell 30 is assembled into the shell 60, there is a large space between the bottom of the cell 30 and the bottom of the battery shell 60, which causes waste of space in the shell 60 and greatly affects the improvement of battery energy density.

[0052] To solve the above problems, as shown in Figure 3 , the first aspect of the present application proposes an electrode sheet 10, which comprises an electrode tab 100 and an electrode sheet body 200, wherein the electrode tab 100 is connected to the electrode sheet body 200. It should be noted that the electrode tab 100 can be separately manufactured, or can be formed by die cutting from the blank area on the electrode sheet body 200. The electrode sheet body 200 has a first edge 210 and a second edge 220 oppositely arranged along the width direction thereof, and the connection between the electrode tab 100 and the electrode sheet body 200 is closer to the first edge 210 and extends out of the electrode sheet body 200 from the first edge 210.

[0053] As shown in Figure 3 and Figure 4 , the electrode sheet 10 can form a cell 30 by winding. For each different winding layer of the cell 30, the projection of the cell 30 in the thickness direction (see the cross-sectional view of the battery shown in Figure 4 ) has an approximately rectangular outer contour, wherein the first edge 210 is superimposed on the top of the outer contour, and the second edge 220 is superimposed on the bottom of the outer contour. A plurality of contour lines 201 are arranged on the electrode sheet 10, and the winding direction of the electrode sheet 10 is changed at the contour lines 201 during winding to form the cell 30. After winding is completed, each contour line 201 is in the same plane.

[0054] It should be noted that the second edge 220 between the two adjacent contour lines 201 is provided with an arc-shaped notch 221, as shown in Figure 3As shown, each of the two adjacent contour lines 201 is provided with an arc-shaped notch 221, and the arc-shaped notch 221 is recessed towards the direction of the first edge 210. Along the length direction of the pole piece 10, the distance from the edge of the arc-shaped notch 221 to the first edge 210 first gradually decreases and then gradually increases. For the convenience of subsequent description, the end of the electric core 30 wound by the first edge 210 is named as the first end 31, and the end of the electric core 30 wound by the second edge 220 is named as the second end 32, as shown in Figure 3 and Figure 4 As shown, the width direction of the pole piece 10 is converted into the length direction of the electric core 30 after winding, and therefore, the first end 31 and the second end 32 are respectively located at the two ends of the electric core 30 along the length direction thereof. Further, the second end 32 of the electric core 30 is formed by the lamination of the second edge 220, and each arc-shaped notch 221 is sequentially communicated along the thickness direction of the electric core 30, so that the projection along the thickness direction of the electric core 30, the second end 32 of the electric core 30 is also arranged in an arc shape, that is, along the width direction of the electric core 30, the distance from the second end 32 to the first end 31 first gradually decreases and then gradually increases.

[0055] Based on the above, the pole piece 10 of the first aspect embodiment of the present application can form an electric core 30 with an arc-shaped bottom after winding, so as to adapt to the shape of the bottom of the battery shell 60. It can be understood that for the same battery shell 60, if the flat-bottomed electric core 30 in the prior art is used, the influence of the deformation of the battery shell 60 is that when the distance between the bottom of the electric core 30 and the middle part of the bottom of the shell 60 reaches the minimum value required by the design, the distance between the bottom of the electric core 30 and the edge part of the bottom of the shell 60 is still large, thereby wasting part of the space. The electric core 30 formed by using the pole piece 10 of the present application has a shape of the bottom of the electric core 30 matched with the shape of the bottom of the shell 60, and further, the width of the pole piece 10 of the present application is wider than that of the pole piece 10 forming the ordinary electric core 30, and after winding to form the electric core 30, the length of the electric core 30 is longer than that of the ordinary electric core 30, so as to increase the content of active material inside the electric core 30, and therefore, the overall energy density of the electric core 30 can be further improved. In addition, due to the small gap between the bottom of the electric core 30 and the battery shell 60, the risk of easy indentation and deformation of the battery shell 60 when subjected to external force impact can be reduced, and the problem of poor appearance of the electric core 30 can be improved.

[0056] In addition, in some implementation scenarios of the prior art, when the soft package battery is subjected to the formation process, the bottom of the aluminum plastic film will protrude outward due to the increase of the air pressure in the accommodating cavity, and the bottom of the aluminum plastic film will be further deformed, as shown in Figure 2As shown, along the thickness direction of the battery cell 30, the distance between the bottom of the shell 60 and the top of the shell 60 is smaller on both sides and larger in the middle. In combination with the foregoing, the shape of the bottom of the aluminum plastic film after being deformed twice is arc-shaped (as shown in Figure 1 As shown, along the width direction of the battery cell 30, it is arc-shaped (as shown in Figure 2 ).

[0057] In view of this situation, the tab 10 of the present application is further improved. Specifically, the second edge 220 is arranged to be inclined as a whole compared with the first edge 210, as shown in Figure 3 As shown, the tab main body 200 has a winding start end 11 and a winding end 12, and the second edge 220 is configured to gradually reduce the distance to the first edge 210 in the direction from the winding start end 11 to the winding end 12. That is, by arranging the second edge 220 to be a slant line intersecting the first edge 210, the width of the tab 10 is gradually reduced in the direction from the winding start end 11 to the winding end 12.

[0058] It can be understood that when the tab 10 is wound to form the battery cell 30, the winding starts from the winding start end 11 and ends at the winding end 12, that is, the winding start end 11 is located inside the battery cell 30, and the winding end 12 is located at the outer periphery of the battery cell 30. It should be noted that after the tab 10 is wound, the width direction of the tab 10 forms the length direction of the battery cell 30. Thus, as shown in Figure 5 As shown, the length of the outer circle layer of the battery cell 30 is shorter, and the length of the inner circle layer of the battery cell 30 is longer, and the distance between the second end 32 and the first end 31 of the battery cell 30 gradually reduces from the inside to the outside of the battery cell 30.

[0059] In summary, the tab 10 of the present application sets the inclined second edge 220 and opens the arc-shaped notch 221 at the second end 32 of the second edge 220, so that the battery cell 30 formed by winding the tab 10 can adapt to the shape of the aluminum plastic film after deformation, thereby having higher active material content and higher energy density.

[0060] Further, the tab main body 200 further includes a current collector and active material layers coated on both sides of the current collector, and the widths of the active material layers on both sides of the current collector are not equal, so as to still meet the OH requirement of adjacent positive and negative active layers when the width of the tab 10 changes. It should be explained that in a lithium ion battery, the area of the negative tab 400 is usually designed to be larger than that of the positive tab 300, and the distance between the edge of the negative tab 400 and the edge of the positive tab 300 is called Overhang (OH). This design can prevent the lithium ions released by the positive electrode from excessive embedding in the edge area of the negative electrode during charging, so as to avoid the risk of battery short circuit, capacity decay or thermal runaway.

[0061] The second aspect of this application provides a battery cell 30, such as... Figure 4 to Figure 7 As shown, the battery cell 30 is formed by winding the electrode sheet 10 described in the above embodiment. Based on the foregoing, the electrode sheet 10 has a starting end 11 and a winding end 12. The electrode sheet 10 is wound from the starting end 11 to the winding end 12 to form the battery cell 30. The width direction of the electrode sheet 10 is converted into the length direction of the battery cell 30. The two ends of the battery cell 30 along the length direction are a first end 31 and a second end 32, respectively. The first end 31 is formed by winding along a first edge 210, and the second end 32 is formed by winding along a second edge 220. Along the thickness direction of the battery cell 30, the distance from the second end 32 to the first end 31 gradually decreases and then gradually increases. That is, in the projection along the thickness direction of the battery cell 30 mentioned above, the second end 32 forms an arc-shaped recess facing the first end 31 to adapt to the shape of the battery casing 60 after deformation during the stamping and packaging process.

[0062] In some embodiments, the distance from the second end 32 to the first end 31, projected along the width direction of the cell 30 and along the thickness direction of the cell 30, gradually increases and then gradually decreases, in order to adapt to the shape of the battery casing 60 after deformation during the formation process.

[0063] In some embodiments, the electrode 10 includes a positive electrode 300 and a negative electrode 400, which are alternately arranged along the direction from the inside to the outside of the cell 30. The positive electrode 300 includes a positive current collector 310, a first positive active layer 320, and a second positive active layer 330. The first positive active layer 320 is coated on the inner side of the positive current collector 310, and the second positive active layer 330 is coated on the outer side of the positive current collector 310. At the second end 32, as... Figure 6 As shown, the second positive electrode active layer 330 is retracted from the first positive electrode active layer 320 along the length direction of the cell 30. That is, the size of the second positive electrode active layer 330 along the length direction of the cell 30 is smaller than the size of the first positive electrode active layer 320 along the length direction of the cell 30.

[0064] Understandably, if the first positive electrode active layer 320 and the second positive electrode active layer 330 have the same dimensions along the length of the cell 30, the dimensions of the corresponding negative electrode active layers (the negative electrode active layer closer to the outer ring is shorter) will result in a lower OH value for the second positive electrode active layer 330 and its corresponding negative electrode active layer closer to the outer ring, posing a risk of lithium plating. Therefore, at the second end 32, the second positive electrode active layer 330 is set shorter than the first positive electrode active layer 320, thereby increasing the OH value of the second positive electrode active layer 330 and its corresponding negative electrode active layer to a set range, thus improving the battery's safety performance.

[0065] In other embodiments, in addition to changing the size of the inner and outer active layers of the positive electrode sheet 300, the size of the inner and outer active layers of the negative electrode sheet 400 can also be changed to make the OH value of the adjacent positive active layer and negative active layer meet the requirements.

[0066] Specifically, as shown in FIG. 4, the negative electrode sheet 400 includes a negative electrode current collector 410, a first negative active layer 420 and a second negative active layer 430, the first negative active layer 420 is coated on the inner side of the negative electrode current collector 410, and the second negative active layer 430 is coated on the outer side of the negative electrode current collector 410. At the second end 32, the first negative active layer 420 protrudes along the length direction of the battery cell 30 compared to the second negative active layer 430, that is, the size of the first negative active layer 420 along the length direction of the battery cell 30 is greater than the size of the second negative active layer 430 along the length direction of the battery cell 30, so that the OH value of the first negative active layer 420 and the positive active layer corresponding thereto (that is, the second positive active layer 330 mentioned above) is increased. Figure 7

[0067] It can be understood that in other embodiments, the size of the inner and outer active layers of the positive electrode sheet 300 can be changed, and the size of the inner and outer active layers of the negative electrode sheet 400 can also be changed to make the adjacent positive electrode sheet 300 and negative electrode sheet 400 meet the OH requirements. Preferably, in any positive electrode sheet 300 and the two negative electrode sheets 400 adjacent thereto, the length difference between the first positive active layer 320 and the second negative active layer 430 of the negative electrode sheet 400 on the inner side thereof is OH1, and the length difference between the second positive active layer 330 and the first negative active layer 420 of the negative electrode sheet 400 on the outer side thereof is OH2, OH1 and OH2 are equal, so that the electrical properties of the electrode sheet 10 of each ring layer are more consistent.

[0068] In addition, as shown in FIG. 4, the electrode sheet 10 also includes a separator 500, any positive electrode sheet 300 and the negative electrode sheet 400 adjacent thereto are separated by the separator 500 to avoid the positive and negative electrode sheets 400 from contacting and short-circuiting. At the second end 32 of the battery cell 30, the negative electrode sheet 400 protrudes compared to the positive electrode sheet 300 adjacent thereto to provide enough lithium intercalation sites to avoid lithium precipitation problems. The separator 500 protrudes compared to the negative electrode sheet 400 adjacent thereto to avoid the electrode sheet 10 from contacting the aluminum plastic film to cause short-circuiting. Figure 5 to Figure 7 The third aspect of the present application further provides a battery including the battery cell 30 of any one of the above-mentioned embodiments. Since the battery of the present application includes the technical solutions of the battery cell 30 in the above-mentioned embodiments, it has all the beneficial effects of the corresponding embodiments, which will not be repeated here.

[0069]

[0070] ​​The utility model embodiment has been explained in detail above in combination with the drawings, but the utility model is not limited to the above-mentioned embodiment, still can make various changes in the knowledge range of the ordinary skill in the art who possesses under the premise of not departing from the utility model's tenet. Besides, the embodiment and the feature in the embodiment of the utility model can be combined mutually under the condition of not conflicting.

Claims

1. A pole piece characterized by, The tab and the tab body are connected, wherein: The tab body has a first edge and a second edge arranged oppositely along the width direction of the tab body, and the tab extends out of the tab body from the first edge; The tab has a plurality of profile lines arranged in parallel and at intervals, and the second edge between any two adjacent profile lines is provided with an arc-shaped notch, and the distance from the edge of the arc-shaped notch to the first edge gradually decreases and then gradually increases along the length direction of the tab.

2. The pole piece of claim 1, wherein The second edge is arranged obliquely compared with the first edge, and the tab body has a winding start end and a winding end, and the distance from the second edge to the first edge gradually decreases along the direction from the winding start end to the winding end.

3. The pole piece of claim 2, wherein The tab body includes a current collector and active material layers coated on both sides of the current collector, and the widths of the active material layers on both sides of the current collector are not equal.

4. An electric cell, characterized by The tab has a winding start end and a winding end, and the tab is wound from the winding start end to the winding end to form the battery cell, and the battery cell has a first end and a second end along the length direction of the battery cell, the first end is formed by winding the first edge, and the second end is formed by winding the second edge; Wherein, in the projection along the thickness direction of the battery cell, the second end is configured to gradually decrease and then gradually increase the distance from the second end to the first end along the width direction of the battery cell.

5. The electric cell of claim 4, wherein, In the projection along the width direction of the battery cell, the second end is configured to gradually increase and then gradually decrease the distance from the second end to the first end along the thickness direction of the battery cell.

6. The electric cell of claim 4, wherein, The tab includes positive tabs and negative tabs, and the positive tabs and the negative tabs are arranged alternately along the direction from the inside to the outside of the battery cell. Wherein, the positive tab includes a positive current collector, a first positive active layer coated on the inner side of the positive current collector, and a second positive active layer coated on the outer side of the positive current collector, and the size of the second positive active layer along the length direction of the battery cell is smaller than the size of the first positive active layer along the length direction of the battery cell at the second end.

7. The electric cell of claim 4, wherein, The tab includes positive tabs and negative tabs, and the positive tabs and the negative tabs are arranged alternately along the direction from the inside to the outside of the battery cell. Wherein, the negative tab includes a negative current collector, a first negative active layer coated on the inner side of the negative current collector, and a second negative active layer coated on the outer side of the negative current collector, and the size of the first negative active layer along the length direction of the battery cell is larger than the size of the second negative active layer along the length direction of the battery cell at the second end.

8. The electric cell of claim 4, wherein, The tab includes positive tabs and negative tabs, and the positive tabs and the negative tabs are arranged alternately along the direction from the inside to the outside of the battery cell. Any of the positive electrode sheet and the two negative electrode sheets adjacent thereto, the positive electrode sheet comprises a positive electrode current collector, and a first positive electrode active layer coated on the inner side of the positive electrode current collector, and a second positive electrode active layer coated on the outer side of the positive electrode current collector, the negative electrode sheet comprises a negative electrode current collector and a negative electrode active layer coated on both sides of the negative electrode current collector respectively, the length difference between the first positive electrode active layer and the adjacent negative electrode active layer is OH1, the length difference between the second positive electrode active layer and the adjacent negative electrode active layer is OH2, OH1 = OH2.

9. The electric cell of claim 4, wherein, The electrode sheet comprises a positive electrode sheet, a negative electrode sheet and a separator, the positive electrode sheet and the negative electrode sheet are arranged alternately along the direction from the inside to the outside of the battery cell, the positive electrode sheet and the negative electrode sheet adjacent thereto are separated by the separator. Among them, in the second end and along the length direction of the battery cell, the negative electrode sheet protrudes compared with the positive electrode sheet adjacent thereto, and the separator protrudes compared with the negative electrode sheet adjacent thereto.

10. A battery characterized by The battery cell comprises any of claims 4 to 9.

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