Battery cell and lithium battery

Abstract

The utility model provides a battery cell and a lithium battery. The battery cell comprises a positive plate, a diaphragm, a negative plate and a diaphragm layer which are laminated and wound, and is provided with a first straight area, a first R-angle area, a second straight area and a second R-angle area which are sequentially connected end to end, the positive plate comprises a positive head part, a double-sided paste-coated foil part, a single-sided paste-coated foil part and a positive tail part which are sequentially connected along the winding direction, the connection junction of the double-sided paste-coated foil part and the single-sided paste-coated foil part is a first connection junction, and the battery cell further comprises a first hot melt adhesive layer and a positive adhesive layer; the positive electrode rubberizing layer extends in the winding direction and is attached to the non-paste side of the single-sided paste foil part, the first hot melt adhesive layer is attached to the first connection junction, and when the first hot melt adhesive layer reaches the melting point, the first hot melt adhesive layer extends to the outer side of the positive electrode rubberizing layer in the first R-angle area, and the second hot melt adhesive layer extends to the outer side of the positive electrode rubberizing layer in the second R-angle area. And the positive electrode adhesive layer is covered at the end part of the first R corner area.

Description

Technical Field

[0001] The present disclosure relates to the technical field of battery cells, and in particular to a battery cell and a lithium battery. Background Art

[0002] For battery cell models with narrower widths, such as battery cells with a width of less than 20 mm, the width of the straight area of ​​the corresponding battery cell is also smaller, so that the single-sided and double-sided junction of the positive electrode paste, i.e., the start and end positions of the glue coating, and the distance between the positive ear position, i.e., the offset distance, are smaller, usually within a spacing of 5 mm. Prior art, such as a pole piece and a lithium-ion battery disclosed in a Chinese patent with application number CN202120442429.1, has adhesive tape attached to the head and tail of the positive electrode sheet, but because the edge of the PET high-temperature adhesive tape attached to the end position of the positive electrode paste is sharp, and the end position of the positive electrode paste is a single-sided paste, i.e., an offset structure, the positive electrode sheet is easily cut off under high pressure formation, so that in the subsequent cycle, the pole sheet has a serious problem of pole sheet fragmentation due to expansion and contraction. Utility Model Content

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a battery cell and a lithium battery that prevents electrode breakage and improves the battery cell yield.

[0004] The purpose of this disclosure is achieved through the following technical solutions:

[0005] A battery cell, comprising:

[0006] The positive electrode sheet, the separator, the negative electrode sheet and the separator layer are stacked and wound, the battery cell is formed with a first straight area, a first R angle area, a second straight area and a second R angle area connected end to end in sequence, the positive electrode sheet includes a positive electrode head, a double-sided pasted foil part, a single-sided pasted foil part and a positive electrode tail part connected in sequence along the winding direction, the connection junction between the double-sided pasted foil part and the single-sided pasted foil part is located in the first straight area, the battery cell also includes a positive electrode ear, the part where the positive electrode ear is welded to the positive electrode tail is located in the second straight area, the connection junction between the double-sided pasted foil part and the single-sided pasted foil part is the first connection junction,

[0007] The battery cell also includes a first hot melt adhesive layer and a positive electrode adhesive layer. The starting end of the positive electrode adhesive layer is located in the first R corner area, and the positive electrode adhesive layer extends along the winding direction and is attached to the non-paste side of the single-sided pasted foil portion. The first hot melt adhesive layer is attached to the first connection junction. The first hot melt adhesive layer is used to extend to the outside of the positive electrode adhesive layer in the first R corner area when the melting point is reached, and cover the end of the positive electrode adhesive layer located in the first R corner area.

[0008] In one embodiment, the connection junction between the single-sided pasted foil portion and the positive electrode tail is located in the first straight area, and the connection junction between the single-sided pasted foil portion and the positive electrode tail is the second connection junction, and also includes a second hot melt adhesive layer, and the second hot melt adhesive layer is attached to the outer side of the portion of the positive electrode tail adjacent to the second connection junction. The positive electrode adhesive layer has a middle break in the first straight area, and the second hot melt adhesive layer covers the middle break. One end of the second hot melt adhesive layer extends to the single-sided pasted foil portion, and the other end of the second hot melt adhesive layer extends to the first R corner area.

[0009] In one embodiment, the hot pressing temperature of the first hot melt adhesive layer is 75° C.-85° C.; and / or,

[0010] The hot pressing temperature of the second hot melt adhesive layer is 75°C-85°C.

[0011] In one embodiment, the thickness of the first hot melt adhesive layer is 65um-70um; and / or,

[0012] The thickness of the second hot melt adhesive layer is 65um-70um.

[0013] In one embodiment, the first hot melt adhesive layer includes a first adhesive layer and a first PET film, and the first adhesive layer is bonded to the first PET film.

[0014] In one embodiment, the second hot melt adhesive layer includes a second adhesive layer and a second PET film, and the second adhesive layer is bonded to the second PET film.

[0015] In one embodiment, the battery cell also includes a negative electrode ear, and the negative electrode sheet includes a negative electrode head, a single-sided pasted area, a double-sided pasted area and a negative electrode tail connected in sequence along the winding direction, and the position where the negative electrode ear is welded to the negative electrode tail is located in the second straight area, and the negative electrode ear is spaced apart from the positive electrode ear.

[0016] In one embodiment, the negative electrode head, the single-sided paste coating area, the double-sided paste coating area and the negative electrode tail are an integrally formed structure.

[0017] In one embodiment, the positive electrode head, the double-sided pasted foil portion, the single-sided pasted foil portion and the positive electrode tail portion are an integrally formed structure.

[0018] A lithium battery comprises the battery cell described in any one of the above embodiments.

[0019] Compared with the prior art, the present invention has at least the following advantages:

[0020] In the above-mentioned battery cell, the positive electrode sheet is provided with a positive electrode head, a double-sided pasted foil portion, a single-sided pasted foil portion and a positive electrode tail in sequence along the winding direction. The connection junction between the double-sided pasted foil portion and the single-sided pasted foil portion is the first connection junction, and the first connection junction is located in the first straight area. The first hot-melt adhesive layer is attached to the non-paste side of the single-sided pasted foil portion. When the first hot-melt adhesive layer is formed, that is, when the first hot-melt adhesive layer reaches the melting point, the thickness becomes thinner and the adhesive overflows to the surrounding areas. The adhesive flows to the outside of the positive electrode adhesive layer in the first R corner area, and covers the end of the positive electrode adhesive layer in the first R corner area. In this way, the edge of the positive electrode adhesive layer of the single-sided pasted foil portion is no longer sharp, and no obvious step is formed, thereby preventing the positive electrode sheet from breaking during formation, thereby improving the battery cell yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 is a schematic structural diagram of a battery cell according to an embodiment;

[0023] Figure 2 for Figure 1 Another structural schematic diagram of the battery cell shown;

[0024] Figure 3 for Figure 1 A schematic structural diagram of the positive electrode sheet of the battery cell shown;

[0025] Figure 4 for Figure 1 A schematic diagram of the structure of the negative electrode sheet of the battery cell shown;

[0026] Figure 5 for Figure 1 A schematic structural diagram of the first hot melt adhesive layer of the battery cell shown. DETAILED DESCRIPTION

[0027] In order to facilitate the understanding of the present disclosure, the present disclosure will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present disclosure are given in the drawings. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present disclosure more thoroughly and comprehensively understood.

[0028] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present disclosure. The terms used herein in the specification of the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0030] The present disclosure provides a battery cell, comprising a positive electrode sheet, a separator, a negative electrode sheet and a separator layer stacked and wound, wherein the battery cell is formed with a first straight area, a first R angle area, a second straight area and a second R angle area connected end to end in sequence, the positive electrode sheet comprises a positive electrode head, a double-sided pasted foil portion, a single-sided pasted foil portion and a positive electrode tail portion connected in sequence along a winding direction, the connection junction between the double-sided pasted foil portion and the single-sided pasted foil portion is located in the first straight area, the battery cell further comprises a positive electrode ear, the portion where the positive electrode ear is welded to the positive electrode tail portion is located in the second straight area, the double-sided pasted foil portion is connected to the positive electrode tail portion, and the positive electrode head portion is connected to the double-sided pasted foil portion. The connection junction between the paste foil portion and the single-sided paste foil portion is the first connection junction. The battery cell also includes a first hot melt adhesive layer and a positive electrode adhesive layer. The starting end of the positive electrode adhesive layer is located in the first R corner area, and the positive electrode adhesive layer extends along the winding direction and is attached to the non-paste side of the single-sided paste foil portion. The first hot melt adhesive layer is attached to the first connection junction. The first hot melt adhesive layer is used to extend to the outside of the positive electrode adhesive layer in the first R corner area when the melting point is reached, and cover the end of the positive electrode adhesive layer located in the first R corner area.

[0031] In the above-mentioned battery cell, the positive electrode sheet is provided with a positive electrode head, a double-sided pasted foil portion, a single-sided pasted foil portion and a positive electrode tail in sequence along the winding direction. The connection junction between the double-sided pasted foil portion and the single-sided pasted foil portion is the first connection junction, and the first connection junction is located in the first straight area. The first hot-melt adhesive layer is attached to the non-paste side of the single-sided pasted foil portion. When the first hot-melt adhesive layer is formed, that is, when the first hot-melt adhesive layer reaches the melting point, the thickness becomes thinner and the adhesive overflows to the surrounding areas. The adhesive flows to the outside of the positive electrode adhesive layer in the first R corner area, and covers the end of the positive electrode adhesive layer in the first R corner area. In this way, the edge of the positive electrode adhesive layer of the single-sided pasted foil portion is no longer sharp, and no obvious step is formed, thereby preventing the positive electrode sheet from breaking during formation, thereby improving the battery cell yield.

[0032] In order to better understand the technical solutions and beneficial effects of the present invention, the present invention is further described in detail below in conjunction with specific embodiments:

[0033] like Figures 1 to 4 As shown, a battery cell 10 of an embodiment includes a positive electrode sheet 100, a separator 200, a negative electrode sheet 300 and a separator layer 400 stacked and wound, and the battery cell 10 is formed with a first straight area 10a, a first R angle area 10b, a second straight area 10c and a second R angle area 10d connected end to end in sequence, and the positive electrode sheet 100 includes a positive electrode head 110, a double-sided pasted foil part 120, a single-sided pasted foil part 130 and a positive electrode tail 140 connected in sequence along the winding direction, and the double-sided pasted foil part 120 is connected to the positive electrode head 110, a double-sided pasted foil part 120, a single-sided pasted foil part 130 and a positive electrode tail part 140. The connection junction between the double-sided pasted foil portion 120 and the single-sided pasted foil portion 130 is located in the first straight area 10a, the battery cell 10 also includes a positive electrode ear 500, and the position where the positive electrode ear 500 is welded to the positive electrode tail 140 is located in the second straight area 10c, and the connection junction between the double-sided pasted foil portion 120 and the single-sided pasted foil portion 130 is the first connection junction 120a, which is also the intersection of the double-sided pasted and single-sided pasted positive electrode sheet 100.

[0034] Furthermore, the battery cell 10 also includes a first hot melt adhesive layer 700a and a positive electrode adhesive layer 800, the starting end of the positive electrode adhesive layer 800 is located in the first R corner area 10b, and the positive electrode adhesive layer 800 extends along the winding direction and is attached to the non-paste side of the single-sided pasted foil portion 120, the first hot melt adhesive layer 700a is attached to the first connection junction 120a, and the first hot melt adhesive layer 700a is used to extend to the outside of the positive electrode adhesive layer 800 in the first R corner area 10b when the melting point is reached, and cover the end of the positive electrode adhesive layer 800 located in the first R corner area 10b.

[0035] It can be understood that the diaphragm 200 and the diaphragm layer 400 prevent the positive electrode sheet 100 and the negative electrode sheet 300 from direct contact and short circuit. When the battery cell 10 is wound, a first straight area 10a, a first R-angle area 10b, a second straight area 10c and a second R-angle area 10d connected end to end are formed. The first R-angle area 10b and the second R-angle area 10d are also bending areas. The positive electrode sheet 100 is coated with paste (i.e., coated with active material) starting from the double-sided pasted foil portion 120. The double-sided pasted foil portion 120 is coated with paste on both sides, and when it extends to the single-sided pasted foil portion 130, the inner side of the single-sided pasted foil portion 130 is coated with paste, while the outer side is not coated with paste. The junction where the double-sided pasted foil portion 120 and the single-sided pasted foil portion 130 are connected is the first connection junction 120a. The first connection junction 120a is located in the first straight area 10a, and the positive ear 500 is located in the second straight area 10c, so that the welding position of the positive ear 500 is separated from the glue at the first connection junction 120a.

[0036] Furthermore, the conventional battery cell 10 is affixed with PET high temperature adhesive tape on the outside of the first connection junction 120a to achieve an insulating and fixing effect, but the edge of the PET high temperature adhesive tape has obvious steps and is relatively sharp, which can easily cut the positive electrode sheet 100 when the battery cell 10 is formed. The present application is to attach a first hot melt adhesive layer 700a to the first connection junction 120a, and the first hot melt adhesive layer 700a becomes thinner and overflows to the surroundings during formation. The overflowing adhesive layer is bonded to the positive electrode adhesive layer 800, so that the edge of the positive electrode adhesive layer 800 is no longer sharp and has no obvious steps, thereby avoiding the positive electrode sheet 100 from being cut under the action of high pressure during formation. In this embodiment, the positive electrode adhesive layer 800 is PET high temperature adhesive tape.

[0037] In the above-mentioned battery cell 10, the positive electrode sheet 100 is provided with a positive electrode head 110, a double-sided pasted foil portion 120, a single-sided pasted foil portion 130 and a positive electrode tail 140 in sequence along the winding direction, the connection junction between the double-sided pasted foil portion 120 and the single-sided pasted foil portion 130 is a first connection junction 120a, the first connection junction 120a is located in the first straight area 10a, the first hot melt adhesive layer 700a is attached to the non-paste side of the single-sided pasted foil portion 130, and the first hot melt adhesive layer 700a is attached to the non-paste side of the single-sided pasted foil portion 130. When layer 700a is formed, that is, when the first hot-melt adhesive layer 700a reaches the melting point, the thickness becomes thinner and the adhesive overflows to the surrounding areas, and the adhesive flows to the outside of the positive electrode adhesive layer 800 in the first R corner area 10b, and covers the end of the positive electrode adhesive layer 800 located in the first R corner area 10b. In this way, the edge of the positive electrode adhesive layer 800 of the single-sided paste-coated foil portion 130 is no longer sharp, and no obvious steps are formed, thereby preventing the positive electrode sheet 100 from breaking during formation, thereby improving the yield of the battery cell 10.

[0038] like Figure 1 , Figure 2 and Figure 3As shown, in one embodiment, the connection junction between the single-sided pasted foil portion 130 and the positive electrode tail 140 is located in the first straight area 10a, and the connection junction between the single-sided pasted foil portion 130 and the positive electrode tail 140 is the second connection junction 130b, and also includes a second hot melt adhesive layer 700b, the second hot melt adhesive layer 700b is attached to the outer side of the portion of the positive electrode tail 140 adjacent to the second connection junction 130b, the positive electrode adhesive layer 800 has a middle break in the first straight area 10a, the second hot melt adhesive layer 700b covers the middle break, one end of the second hot melt adhesive layer 700b extends to the single-sided pasted foil portion 130, and the other end of the second hot melt adhesive layer 700b extends to the first R corner area 10b. It can be understood that the positive electrode adhesive layer 800 is attached to the single-sided paste-coated foil portion 130 and the positive electrode tail 140, and the positive electrode adhesive layer 800 of the first straight area 10a has a middle port, and the second hot melt adhesive layer 700b covers the middle port. The second hot melt adhesive layer 700b becomes thinner and overflows to the surroundings during formation, and the overflowed adhesive layer adheres to the positive electrode adhesive layer 800, so that the edge of the positive electrode adhesive layer 800 of the first straight area 10a is no longer sharp, and no obvious steps are formed to prevent the positive electrode sheet 100 from breaking during formation.

[0039] In one embodiment, the hot pressing temperature of the first hot melt adhesive layer 700a is 75°C-85°C, and the hot pressing temperature of the second hot melt adhesive layer 700b is 75°C-85°C. In this embodiment, the hot pressing temperatures of the first hot melt adhesive layer 700a and the second hot melt adhesive layer 700b are both 75°C, so that the first hot melt adhesive layer 700a and the second hot melt adhesive layer 700b become thinner during hot pressing, and the adhesive layer overflows to the surroundings, so that the edge of the positive electrode adhesive is no longer sharp and no obvious steps are formed.

[0040] In one embodiment, the thickness of the first hot melt adhesive layer 700a is 65um-70um. In this embodiment, the thickness of the first hot melt adhesive layer 700a is 65um, and the thickness of the first hot melt adhesive layer 700a is reduced to 30um after hot pressing.

[0041] In one embodiment, the thickness of the second hot melt adhesive layer 700b is 65um-70um. In this embodiment, the thickness of the second hot melt adhesive layer 700b is 65um, and the thickness of the second hot melt adhesive layer 700b is reduced to 30um after hot pressing.

[0042] like Figure 5As shown, in one embodiment, the first hot melt adhesive layer 700a includes a first adhesive layer 710 and a first PET film 720, and the first adhesive layer 710 is bonded to the first PET film 720. In this embodiment, the first PET film 720 is a release film, and the first PET film 720 is torn off during attachment to bond the first adhesive layer 710 to the positive electrode sheet 100.

[0043] In one embodiment, the second hot melt adhesive layer 700b includes a second adhesive layer and a second PET film, and the second adhesive layer is bonded to the second PET film. In this embodiment, the second PET film is a release film, and the second PET film is torn off during attachment to bond the second adhesive layer to the positive electrode sheet 100.

[0044] like Figure 4 As shown, in one embodiment, the battery cell 10 further includes a negative electrode ear 600, and the negative electrode sheet 300 includes a negative electrode head 310, a single-sided paste area 320, a double-sided paste area 330 and a negative electrode tail 340 connected in sequence along the winding direction. The portion where the negative electrode ear 600 is welded to the negative electrode tail 340 is located in the second straight area 10c, and the negative electrode ear 600 is spaced apart from the positive electrode ear 500. In this embodiment, the single-sided paste area 320 of the negative electrode sheet 300 is arranged correspondingly to the double-sided paste foil portion 120 of the positive electrode sheet 100, and the double-sided paste area 330 of the negative electrode sheet 300 is arranged correspondingly to the single-sided paste foil portion 130 of the positive electrode sheet 100, so that the energy density of the battery cell 10 is higher. Further, the negative electrode ear 600 is welded to the negative electrode tail 340, and the negative electrode ear 600 is located in the second straight area 10c, so that the structure of the battery cell 10 is more compact.

[0045] In one embodiment, the negative electrode head 310 , the single-sided paste coating area 320 , the double-sided paste coating area 330 and the negative electrode tail 340 are an integrally formed structure, so that the negative electrode sheet 300 has a higher structural strength.

[0046] In one embodiment, the positive electrode head 110 , the double-sided pasted foil portion 120 , the single-sided pasted foil portion 130 , and the positive electrode tail 140 are an integrally formed structure, so that the positive electrode sheet 100 has a higher structural strength.

[0047] The present application also provides a lithium battery, comprising the battery cell 10 described in any of the above embodiments.

[0048] Compared with the prior art, the present invention has at least the following advantages:

[0049] In the above-mentioned battery cell 10, the positive electrode sheet 100 is provided with a positive electrode head 110, a double-sided pasted foil portion 120, a single-sided pasted foil portion 130 and a positive electrode tail 140 in sequence along the winding direction, the connection junction between the double-sided pasted foil portion 120 and the single-sided pasted foil portion 130 is a first connection junction 120a, the first connection junction 120a is located in the first straight area 10a, the first hot melt adhesive layer 700a is attached to the non-paste side of the single-sided pasted foil portion 130, and the first hot melt adhesive layer 700a is attached to the non-paste side of the single-sided pasted foil portion 130. When layer 700a is formed, that is, when the first hot-melt adhesive layer 700a reaches the melting point, the thickness becomes thinner and the adhesive overflows to the surrounding areas, and the adhesive flows to the outside of the positive electrode adhesive layer 800 in the first R corner area 10b, and covers the end of the positive electrode adhesive layer 800 located in the first R corner area 10b. In this way, the edge of the positive electrode adhesive layer 800 of the single-sided paste-coated foil portion 130 is no longer sharp, and no obvious steps are formed, thereby preventing the positive electrode sheet 100 from breaking during formation, thereby improving the yield of the battery cell 10.

[0050] The above-mentioned embodiments only express several implementation methods of the present disclosure, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the utility model patent. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present disclosure, and these all belong to the protection scope of the present disclosure. Therefore, the protection scope of the patent of the present disclosure shall be based on the attached claims.

Claims

1. A battery cell, comprising a positive electrode sheet, a separator, a negative electrode sheet and a separator layer stacked and wound, the battery cell forming a first straight area, a first R angle area, a second straight area and a second R angle area connected end to end in sequence, the positive electrode sheet comprising a positive electrode head, a double-sided pasted foil portion, a single-sided pasted foil portion and a positive electrode tail portion connected in sequence along the winding direction, the connection junction between the double-sided pasted foil portion and the single-sided pasted foil portion is located in the first straight area, the battery cell also includes a positive electrode ear, the portion where the positive electrode ear is welded to the positive electrode tail is located in the second straight area, the connection junction between the double-sided pasted foil portion and the single-sided pasted foil portion is a first connection junction, characterized in that, The battery cell also includes a first hot melt adhesive layer and a positive electrode adhesive layer. The starting end of the positive electrode adhesive layer is located in the first R corner area, and the positive electrode adhesive layer extends along the winding direction and is attached to the non-paste side of the single-sided pasted foil portion. The first hot melt adhesive layer is attached to the first connection junction. The first hot melt adhesive layer is used to extend to the outside of the positive electrode adhesive layer in the first R corner area when the melting point is reached, and cover the end of the positive electrode adhesive layer located in the first R corner area.

2. The battery cell according to claim 1, characterized in that: The connection junction between the single-sided pasted foil portion and the positive electrode tail is located in the first straight area, and the connection junction between the single-sided pasted foil portion and the positive electrode tail is the second connection junction, and also includes a second hot-melt adhesive layer, and the second hot-melt adhesive layer is attached to the outer side of the portion of the positive electrode tail adjacent to the second connection junction. The positive electrode adhesive layer has a middle break in the first straight area, and the second hot-melt adhesive layer covers the middle break. One end of the second hot-melt adhesive layer extends to the single-sided pasted foil portion, and the other end of the second hot-melt adhesive layer extends to the first R corner area.

3. The battery cell according to claim 2, characterized in that: The hot pressing temperature of the first hot melt adhesive layer is 75° C.-85° C.; and / or, The hot pressing temperature of the second hot melt adhesive layer is 75°C-85°C.

4. The battery cell according to claim 2, characterized in that: The thickness of the first hot melt adhesive layer is 65um-70um; and / or, The thickness of the second hot melt adhesive layer is 65um-70um.

5. The battery cell according to claim 1, characterized in that: The first hot melt adhesive layer includes a first adhesive layer and a first PET film, and the first adhesive layer is bonded to the first PET film.

6. The battery cell according to claim 2, characterized in that: The second hot-melt adhesive layer includes a second adhesive layer and a second PET film, and the second adhesive layer is bonded to the second PET film.

7. The battery cell according to claim 1, characterized in that: The battery cell also includes a negative electrode ear, and the negative electrode sheet includes a negative electrode head, a single-sided pasted area, a double-sided pasted area and a negative electrode tail connected in sequence along the winding direction. The position where the negative electrode ear is welded to the negative electrode tail is located in the second straight area, and the negative electrode ear is spaced apart from the positive electrode ear.

8. The battery cell according to claim 7, characterized in that: The negative electrode head, the single-sided paste coating area, the double-sided paste coating area and the negative electrode tail are an integrally formed structure.

9. The battery cell according to claim 1, characterized in that: The positive electrode head, the double-sided pasted foil portion, the single-sided pasted foil portion and the positive electrode tail portion are an integrally formed structure.

10. A lithium battery, characterized in that: A battery cell comprising the battery cell according to any one of claims 1 to 8.

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