Battery cell, secondary battery, and electronic device

Abstract

Disclosed in the present application are a battery cell, a secondary battery, and an electronic device. The battery cell comprises a packaging bag comprising a first folding portion and a second folding portion, the first folding portion having a first cut edge and a first folding line, and the second folding portion having a second cut edge and a second folding line. The first folding line, the second folding line, the first cut edge, and the second cut edge intersect at a first vertex, or, the extension line of the first folding line and the extension line of the second folding line intersect at the first vertex.

Description

Battery cell, secondary battery and electronic device

[0001] Related applications

[0002] The present application claims priority to the following Chinese patent application:

[0003] Application No. 2024113104587, entitled "Battery cell, secondary battery and electronic device", filed on September 19, 2024;

[0004] The above patent is hereby incorporated by reference in its entirety into the present application. TECHNICAL FIELD

[0005] The present application relates to the technical field of electrochemical devices, and in particular to a battery cell, a secondary battery and an electronic device. BACKGROUND

[0006] With the wide application of secondary batteries, the improvement of energy density has become the core pursuit of research and development. In a secondary battery, in order to achieve higher volumetric energy density, unnecessary volume waste needs to be minimized or compressed in the design stage to improve the volumetric utilization of the battery cell, which has higher design requirements for the packaging structure of the battery cell. SUMMARY

[0007] The present application provides a battery cell, a secondary battery and an electronic device, which can improve the volume waste problem caused by the packaging structure of the battery cell.

[0008] In a first aspect, the present application provides a battery cell, which comprises a packaging bag, the packaging bag comprising a packaging body and a sealing portion connected to the packaging body. The sealing portion comprises a first folding portion and a second folding portion. The first folding portion has a first folding line, and further comprises a first cut edge facing the second folding portion, the first cut edge intersecting the first folding line at a first end point. The second folding portion has a second folding line, and further comprises a second cut edge facing the first folding portion, the second cut edge intersecting the second folding line at a second end point. The first folding line and the second folding line are arranged at an included angle, and the included angle between the first cut edge and the second cut edge is γ, 90°≤γ≤180°. The first folding line, the second folding line, the first cut edge and the second cut edge intersect at a first vertex, or the extension line of the first folding line intersects the extension line of the second folding line at the first vertex.

[0009] Based on the above embodiment, by cutting the corner position of the packaging bag, the first folding portion with the first cut edge and the second folding portion with the second cut edge are formed, which avoids the overlap of the first folding portion and the second folding portion at the corner position of the packaging bag. In this way, the first folding portion and the second folding portion can be folded and fixed at the same time and shaped, so that the packaging bag is folded to form a more compact structure, achieving the purpose of reducing the size of the battery cell and improving the volume waste in the packaging of the battery cell.

[0010] In some embodiments, the distance from the first end point to the first vertex in the extension direction of the first folding line is a1, and the distance from the second end point to the first vertex in the extension direction of the second folding line is a2, 0mm≤a1≤2.0mm, and 0mm≤a2≤2.0mm.

[0011] Based on the above embodiments, by controlling a1 and a2 to be within the above ranges, it is avoided that the cutting removal area at the corner position is too small to remove the sealing edge, so that the first folding part and the second folding part cannot be folded at the same time, and it is also avoided that the cutting removal area at the corner position is too large to make the sealing of the corner part of the sealing part 12 unreliable, causing sealing failure and affecting the safety of the battery cell.

[0012] In some embodiments, one end of the first cutting edge extends to the outer edge of the first folding part, and the included angle between the first cutting edge and the first folding line is a1; one end of the second cutting edge extends to the outer edge of the second folding part, and the included angle between the second cutting edge and the second folding line is a2; and the battery cell satisfies at least one of the following conditions: (1) 0°<a1≤90°; and (2) 0°<a2≤90°.

[0013] Based on the above embodiments, by setting a1 and a2 within the range of (0°, 90°], it is further avoided that the first folding part and the second folding part overlap at the corner position of the packaging bag, and the obstruction of the sealing edge overlap area at the corner position is eliminated.

[0014] In some embodiments, at least one of the first end point and the second end point is spaced apart from the first vertex, and the sealing part has a first corner line connected between the first end point and the second end point; and the battery cell satisfies at least one of the following conditions: (1) the minimum distance from the first vertex to the first corner line is L, and 0mm≤L≤1.0mm; and (2) the included angle between the first folding line and the second folding line is θ, and 85°≤θ≤95°.

[0015] Based on the above embodiments, the corner position of the packaging bag also forms a first corner line after cutting, and by controlling L to be within the above range, it is ensured that the sealing edge overlap area is completely removed, and the sealing efficiency of the sealing part at the first corner line is ensured.

[0016] In some embodiments, the inner edge of the first folding part and the inner edge of the second folding part intersect at a fourth end point, and the minimum distance from the fourth end point to the first corner line is B, and 1.2mm≤B≤2.0mm.

[0017] Based on the above embodiments, by controlling the distance from the fourth end point to the first corner line, it is ensured that the corner position has sufficient sealing width after cutting.

[0018] In some embodiments, the sealing portion further has an inner corner boundary line, the inner corner boundary line is connected between the inner edge of the first folding portion and the inner edge of the second folding portion, and the inner corner boundary line is spaced apart from the first cutting corner line.

[0019] Based on the above embodiments, by means of the inner corner boundary line spaced apart from the first cutting corner line, the inner edge of the sealing portion is extended inward, and under the premise of ensuring that the corner position is cut and has sufficient sealing width, the range of the first cutting corner line can be larger.

[0020] In some embodiments, the inner corner boundary line is parallel to the first cutting corner line; the minimum distance between the inner corner boundary line and the first cutting corner line is T1, and 1.2mm≤T1≤2.4mm.

[0021] Based on the above embodiments, by controlling T1 to meet the above range, the sealing reliability of the corner position after cutting is ensured.

[0022] In some embodiments, the minimum distance between the inner corner boundary line and the first cutting edge is T2, T2 satisfies: 1.2mm≤T2≤2.4mm; and the minimum distance between the inner corner boundary line and the second cutting edge is T3, T3 satisfies: 1.2mm≤T3≤2.4mm.

[0023] Based on the above embodiments, by controlling T2 and T3 to meet the above range, the sealing reliability of the corner position after cutting is ensured.

[0024] In some embodiments, the battery cell further includes a battery cell monomer arranged in the internal space of the packaging body, the battery cell monomer has a second cutting corner line corresponding to the first vertex; the two ends of the second cutting corner line intersect the first outer edge and the second outer edge of the battery cell monomer, respectively; the extension line of the first outer edge, the extension line of the second outer edge and the second cutting corner line define a battery cell cutting corner area, and in the thickness direction of the battery cell, the projection area of the battery cell cutting corner area is M, 0.10mm 2 ≤M≤6.31mm 2 .

[0025] Based on the above embodiments, in order to ensure the sealing effect of the corner position of the packaging bag, the battery cell monomer is cut, and by controlling the projection area M of the battery cell cutting corner area to be in the range of [0.10mm 2 , 6.31mm 2 ], the area of the battery cell cutting corner area is avoided to be too large, so that the capacity of the battery cell is excessively reduced, resulting in a decrease in energy density, and the area of the battery cell cutting corner area is avoided to be too small, resulting in insufficient sealing width of the corner position of the packaging bag, affecting the sealing effect.

[0026] In some embodiments, the first folding line is located between the inner edge and the outer edge of the first folding portion; in a direction perpendicular to the first folding line, the distance from the first folding line to the inner edge of the first folding portion is s1, 0.1mm≤s1≤1.0mm, and the distance between the inner edge and the outer edge of the first folding portion is k1, 1.0mm≤k1≤4.0mm; the second folding line is located between the inner edge and the outer edge of the second folding portion; in a direction perpendicular to the second folding line, the distance from the second folding line to the inner edge of the second folding portion is s2, 0.1mm≤s2≤1.0mm, and the distance between the inner edge and the outer edge of the second folding portion is k2, 0.6mm≤k2≤4.0mm.

[0027] Based on the above embodiments, in the unfolded state of the packaging bag, the position of the first folding line is determined by controlling the distance from the first folding line to the inner edge and the outer edge of the first folding portion, and the position of the second folding line is determined by controlling the distance from the second folding line to the inner edge and the outer edge of the second folding portion, thereby avoiding excessive extrusion of the first folding portion and the second folding portion after folding or still occupying a large space after folding.

[0028] In some embodiments, along the length direction of the battery cell, the first folding portion is located on one side of the packaging body, along the width direction of the battery cell, the second folding portion is located on one side of the packaging body, and the length direction, the width direction and the thickness direction of the battery cell are perpendicular to each other; the battery cell further comprises a tab, and the tab is connected to the first folding portion and extends from the first folding portion.

[0029] Based on the above embodiments, the first folding portion is located on one side of the packaging body along the length direction of the battery cell, and the top sealing edge of the battery cell can be folded; the second folding portion is located on one side of the packaging body along the width direction of the battery cell, and the side sealing edge of the battery cell can be folded; in this way, the battery cell can be completely folded to achieve the purpose of reducing the size of the battery cell.

[0030] In some embodiments, the packaging body has two first sides arranged opposite along the length direction of the battery cell, and two second sides arranged opposite along the width direction of the battery cell; the first folding portion has a first folding edge and a first straight edge, the first folding edge is located between the outer edge and the first folding line, and the first straight edge is located between the inner edge and the first folding line; the second folding portion has a second folding edge and a second straight edge, the second folding edge is located between the outer edge and the second folding line, and the second straight edge is located between the inner edge and the second folding line; wherein the first folding edge is folded relative to the first straight edge and connected to one of the first sides, the second folding edge is folded relative to the second straight edge, and the two second folding edges are connected to the two second sides one by one.

[0031] Based on the above embodiment, the first folding area in the first folding part is folded and connected to one side of the packaging body along the length direction of the battery cell, so as to realize the folding of the top sealing edge of the packaging bag, and the second folding area in the second folding part is folded and connected to one side of the packaging body along the width direction of the battery cell, so as to realize the folding of the side sealing edge of the packaging bag.

[0032] In some embodiments, the battery cell further comprises a battery cell monomer, the packaging bag comprises a packaging film, the packaging film is wound from one side of the battery cell monomer to the other side of the battery cell monomer, and after the film is folded, a packaging body, a first folding part and two second folding parts are formed, and the battery cell monomer is arranged in the internal space of the packaging body.

[0033] Based on the above embodiment, the two corner positions on both sides of the top sealing edge of the packaging bag are cut, two second folding parts are formed, the battery cell is completely folded, and the size of the battery cell is reduced.

[0034] In a second aspect, the application further provides a secondary battery, comprising: a shell; and the above-mentioned battery cell, which is arranged in the internal space of the shell.

[0035] In a third aspect, the application further provides an electronic device comprising a secondary battery.

[0036] Based on the battery cell, the secondary battery and the electronic device provided in the embodiments of the application, the packaging bag in the embodiments of the application comprises a sealing part having a first folding part and a second folding part, the first folding part is provided with a first cutting edge, and the second folding part is provided with a second cutting edge, so that there is a gap between the first folding part and the second folding part which are folded, the first folding part and the second folding part do not overlap at the corner part of the packaging bag, the first folding part and the second folding part are folded and fixed to be shaped, the packaging bag is packaged to form a more compact structure, the size of the battery cell is reduced, the problem of volume waste in the packaging of the battery cell is improved, and the energy density of the battery cell is improved. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0038] FIG. 1 is an unfolded schematic view of a battery cell according to an embodiment of the application;

[0039] FIG. 2 is a cross-sectional schematic view of a battery cell according to an embodiment of the application;

[0040] FIG. 3 is a partial enlarged schematic view of FIG. 1;

[0041] Figure 4 is another enlarged view of a part of Figure 1;

[0042] Figure 5 is a schematic diagram of the structure of a cutting and removal area according to an embodiment of this application;

[0043] Figure 6 is a schematic diagram of another cut-out area according to an embodiment of this application;

[0044] Figure 7 is a schematic diagram of the structure of another cutting and removal area according to an embodiment of this application;

[0045] Figure 8 is a structural schematic diagram of a corner sealing part according to an embodiment of this application;

[0046] Figure 9 is a schematic diagram of another corner sealing part according to an embodiment of this application;

[0047] Figure 10 is a structural schematic diagram of another corner sealing part according to an embodiment of this application;

[0048] Reference numerals: 1. Battery cell; 10. Packaging bag; 20. Single battery cell; 30. Tab; 11. Packaging body; 12. Sealing part; 21. First outer edge; 22. Second outer edge; 23. Second chamfer line; 110. Receiving cavity; 121. First fold; 122. Second fold; 123. Corner sealing part; 410. First dividing line; 420. Second dividing line; 430. Third dividing line; 440. Fourth dividing line; 1211. First fold line; 1212. First chamfer; 1213. First inner boundary line; 1214. First outer boundary line; 1221. Second fold line; 1222. Second chamfer; 1223. Second inner boundary line; 1224. Second outer boundary line; 1231. First chamfer line; 1232. Inner corner boundary line. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0050] In the cell packaging process of secondary batteries, after the packaging bag is heat-sealed to form a seal, the seal is usually folded to reduce the assembly size of the cell. In related technologies, the top and side seals at the corners of the packaging bag often overlap, causing interference between the folded edges of the top and side seals. Therefore, the side seals are usually folded to reduce the width of the packaging bag and increase the energy density of the cell. However, this cell packaging structure makes it difficult to fold the top seal, which occupies space along the length of the cell, resulting in significant volume waste.

[0051] In order to solve the above problems in the related art, the application provides an electric core, a secondary battery and an electronic device. The sealing part of the packaging bag has a first folding part and a second folding part, and the first folding part has a first cutting edge and the second folding part has a second cutting edge, so that there is a gap between the first folding part and the second folding part. The first folding part can be folded along the first folding line to complete the edge folding process, and the second folding part can be folded along the second folding line to complete the edge folding process. In this way, the first folding part and the second folding part can be folded and fixed, and they do not interfere with each other when being folded. The space occupied by the packaging bag in the length direction of the electric core and the space occupied by the packaging bag in the width direction are both reduced. The electric core can be packaged to form a more compact mechanism, thereby reducing the size of the electric core and improving the volumetric energy density.

[0052] As shown in FIG. 1, it is an unfolded schematic view of an electric core 1 according to an embodiment of the application. FIG. 2 is a cross-sectional schematic view of the electric core 1 according to an embodiment of the application. The electric core 1 according to the embodiment of the application includes a packaging bag 10, an electric core monomer 20 and an electrolyte. The packaging bag 10 has a packaging main body 11 and a sealing part 12. The packaging main body 11 forms an accommodation cavity 110. The electric core monomer 20 is arranged in the accommodation cavity 110, and the electrolyte is filled in the accommodation cavity 110 and infiltrates the electric core monomer 20. The sealing part 12 is connected to the packaging main body 11 to form a sealed space in the accommodation cavity 110, thereby preventing the electrolyte in the accommodation cavity 110 from overflowing.

[0053] The electric core monomer 20 includes a positive electrode sheet, a negative electrode sheet and a separator. The positive electrode sheet, the separator and the negative electrode sheet are sequentially laminated to form the electric core monomer 20, i.e., the electric core monomer 20 is a laminated electric core monomer. Alternatively, the positive electrode sheet, the separator and the negative electrode sheet are sequentially laminated and wound to form the electric core monomer 20, i.e., the electric core monomer 20 is a wound electric core monomer. In the embodiment of the application, the lamination direction of the positive electrode sheet, the separator and the negative electrode sheet is the thickness direction Z of the electric core 1.

[0054] The electric core 1 further includes a tab 30. The tab 30 includes a positive electrode tab and a negative electrode tab. The positive electrode tab is electrically connected to the positive electrode sheet, and the negative electrode tab is electrically connected to the negative electrode sheet. As shown in FIG. 1, in the embodiment of the application, the tab 30 is connected to the electric core monomer 20 and extends out of the packaging bag 10 along the length direction X of the electric core 1. The two tabs 30 are arranged side by side in the width direction Y of the electric core 1. The two tabs 30 include one positive electrode tab and one negative electrode tab. The width direction Y, the length direction X and the thickness direction Z of the electric core 1 are perpendicular to each other.

[0055] The sealing part 12 comprises a first folding part 121, a second folding part 122 and a corner sealing part 123, wherein the two tabs 30 are connected to the first folding part 121 and extend from the first folding part 121. The first folding part 121 is connected to one side of the packaging body 11 along the length direction Y of the battery cell 1. The sealing part 12 comprises two second folding parts 122, which are respectively connected to the opposite sides of the packaging body 11 along the width direction X of the battery cell 1. The first folding part 121 and the second folding part 122 are arranged at an angle, and the corner sealing part 123 is connected between the first folding part 121 and the second folding part 122. In the embodiment, the first folding part 121 and the second folding part 122 are at least partially spaced apart, so that both of them can complete the edge folding process and achieve the purpose of reducing the packaging bag 10 packaging size.

[0056] Further, the packaging body 11 has two first sides and two second sides, the two first sides are oppositely arranged along the length direction Y of the battery cell 1, and the two second sides are oppositely arranged along the width direction X of the battery cell 1. The first folding part 121 has a first folding edge and a first straight edge, the first folding edge is located between the outer edge and the first folding line 1211, and the first straight edge is located between the inner edge and the first folding line 1211. The second folding part 122 has a second folding edge and a second straight edge, the second folding edge is located between the outer edge and the second folding line 1221, and the second straight edge is located between the inner edge and the second folding line 1221. The first folding edge is folded relative to the first straight edge and connected to one of the first sides, and the second folding edge is folded relative to the second straight edge connected thereto, and the two second folding edges are respectively connected to the two second sides. In specific implementation, the first folding edge can be connected to the first side of the packaging body 11 in a flat state, or can be connected to the first side of the packaging body 11 in a folded state, and the second folding edge can be connected to the second side of the packaging body 11 in a flat state, or can be connected to the second side of the packaging body 11 in a folded state. In this way, the first folding edge in the first folding part 121 is folded and connected to the side of the packaging body 11 along the length direction Y of the battery cell 1 to realize the edge folding of the top sealing edge of the packaging bag 10, and the second folding edge in the second folding part 122 is folded and connected to the side of the packaging body 11 along the width direction X of the battery cell 1 to realize the edge folding of the side sealing edge of the packaging bag 10.

[0057] Referring to FIGS. 3-4, FIG. 3 is a partial enlarged view of FIG. 1, and FIG. 4 is another partial enlarged view of FIG. 1. Specifically, the first folding portion 121 has a first folding line 1211 spaced apart from an inner edge thereof, and has a first cut edge 1212 on a side thereof facing the second folding portion 122, the first cut edge 1212 intersecting the first folding line 1211 at a first end point. The second folding portion 122 has a second folding line 1221 spaced apart from an inner edge thereof, and has a second cut edge 1222 on a side thereof facing the first folding portion, the second cut edge 1222 intersecting the second folding line 1221 at a second end point. The first folding line 1211 and the second folding line 1221 are arranged at an angle, and the angle between the first cut edge 1212 and the second cut edge 1222 is γ, 90°≤γ≤180°. The angle formed by rotating the first cut edge 1212 toward a direction away from the inner edge of the first folding portion 121 to the second cut edge 1222 is γ, and in the embodiment, the angle γ between the first cut edge 1212 and the second cut edge 1222 satisfies γ+θ+α1+α2=360°, where θ is the angle between the first folding line 1211 and the second folding line 1221, α1 is the angle between the first cut edge 1212 and the first folding line 1211, and α2 is the angle between the second cut edge 1222 and the second folding line 1221.

[0058] In a specific implementation, the material of the packaging bag 10 can be melted and then pressed and sealed, for example, a heat sealing method is used to process the sealing area. After the battery cell 1 is packaged, the packaging bag 10 forms a sealing area. The sealing area is cut according to a predetermined cutting boundary line to form the first cut edge 1212 and the second cut edge 1222, and then the sealing portion 12 including the first folding portion 121 and the second folding portion 122 is obtained. In this way, when the packaging bag 10 is packaged, the first folding portion 121 and the second folding portion 122 can be folded and fixed to the side surface of the packaging body 11, so that the packaging of the packaging bag 10 is more compact, which helps to improve the energy density of the battery cell 1.

[0059] In an embodiment of the present application, the packaging bag 10 is in an unfolded state, the first folding part 121 has an inner edge and an outer edge arranged at intervals, the inner edge of the first folding part 121 is named as a first inner boundary line 1213, and the outer edge of the first folding part 121 is named as a first outer boundary line 1214. The first inner boundary line 1213 and the first outer boundary line 1214 are located on opposite sides of the first folding line 1211, and in a direction perpendicular to the first folding line 1211, the first inner boundary line 1213 is located on a side of the first folding line 1211 close to the packaging body 11, and the first outer boundary line 1214 is located on a side of the first folding line 1211 away from the packaging body 11. In an embodiment of the present application, when the first folding part 121 is edge folded: if the distance between the first folding line 1211 and the first inner boundary line 1213 is too close, the edge folding is not easy to fold, the folding of the first folding part 121 causes stress to the packaging body 11, and then causes extrusion to the battery cell monomer 20 and the electrolyte in the packaging body 11, thereby causing deformation of the battery cell monomer 20 and deterioration of the cycle performance; if the distance between the first folding line 1211 and the first inner boundary line 1213 is too far, the space occupied by the first folding part 121 after folding increases, which is not conducive to the improvement of the energy density of the battery cell 1, and therefore the position of the first folding line 1211 relative to the first inner boundary line 1213 needs to be controlled. For example, in a direction perpendicular to the extension line of the first folding line 1211, the distance between the first folding line 1211 and the first inner boundary line 1213 is s1, and s1 satisfies: 0.1mm≤s1≤1.0mm. For example, s1 can be 0.1mm, 0.4mm, 0.5mm, 0.6mm, 0.8mm, 1.0mm, or a range formed by any two of them.

[0060] Further, the distance between the first folding line 1211 and the first outer boundary line 1214 is k1, and 1.0mm≤k1≤4.0mm. Alternatively, k1 can be 1.0mm, 1.25mm, 1.5mm, 1.75mm, 2.0mm, 2.5mm, 3.0mm, 4.0mm, or a range formed by any two of them. If k1<1.0mm, the edge folding is not easy to fold, the sealing width of the first folding part 121 is insufficient, and the edge is easy to enter water vapor, which causes insufficient service life of the battery cell 1 to ensure effective packaging; if k1>4.0mm, after edge folding, the width of the edge exceeds the thickness of the battery cell monomer 20, which affects the thickness size of the battery cell 1.

[0061] In an embodiment of the present application, the packaging bag 10 is in an unfolded state, and the second folding part 122 further has an inner edge and an outer edge arranged at intervals. The inner edge of the second folding part 122 is named as a second inner boundary line 1223, and the outer edge of the second folding part 122 is named as a second outer boundary line 1224. The second inner boundary line 1223 and the second outer boundary line 1224 are located on opposite sides of the second folding line 1221. In a direction perpendicular to the second folding line 1221, the second inner boundary line 1223 is located on a side of the second folding line 1221 close to the packaging body 11, and the second outer boundary line 1224 is located on a side of the second folding line 1221 away from the packaging body 11. In an embodiment of the present application, when the second folding part 122 is edge folded: if the distance between the second folding line 1221 and the second inner boundary line 1223 is too close, the edge folding is not easy to fold, the folding of the second folding part 122 causes stress to the packaging body 11, and then causes extrusion to the battery cell monomer 20 and the electrolyte in the packaging body 11, thereby causing deformation of the battery cell monomer 20 and deterioration of the cycle performance; if the distance between the second folding line 1221 and the second inner boundary line 1223 is too far, the space occupied by the second folding part 122 after folding is increased, which is not conducive to the improvement of the energy density of the battery cell 1, and therefore the position of the second folding line 1221 relative to the second inner boundary line 1223 needs to be controlled. In a direction perpendicular to the extension line of the second folding line 1221, the distance between the second folding line 1221 and the second inner boundary line 1223 is s2, and s2 satisfies: 0.1 mm≤s2≤1.0 mm. For example, s2 can be 0.1 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.8 mm, 1.0 mm, or a range formed by any two of them. In specific implementation, a person skilled in the art can determine the value of s2 according to the thickness of the second folding part 122 and the edge folding process of the second folding part 122, for example, when the thickness of the second folding part 122 is relatively thick, or the second folding part 122 adopts a two-fold process, s2 takes a larger value.

[0062] Further, the distance between the second folding line 1221 and the second outer boundary line 1224 is k2, and k2 satisfies: 0.6 mm≤k2≤4.0 mm. Optionally, k2 can be 0.6 mm, 1.0 mm, 1.25 mm, 1.5 mm, 1.75 mm, 2.0 mm, 2.5 mm, 3.0 mm, 4.0 mm, or a range formed by any two of them. If k2<0.6 mm, the edge folding is not easy to fold, the sealing width of the second folding part 122 is insufficient, and the edge is easy to enter water vapor, which causes insufficient service life of the battery cell 1 to ensure effective packaging. If k2>4.0 mm, after edge folding, the width of the edge exceeds the thickness of the battery cell monomer 20, which affects the thickness size of the battery cell 1.

[0063] The first cutting edge 1212 and the second cutting edge 1222 in the present application will be introduced below in combination with specific embodiments.

[0064] As shown in FIG. 3, the extension line of the first folding line 1211, the first outer boundary line 1214, the extension line of the second folding line 1221 and the second outer boundary line 1224 jointly define the edge sealing overlapping area. In the embodiment of the present application, the extension line of the first folding line 1211 intersects with the extension line of the second folding line 1221 at the first vertex, the first cutting edge 1212 has a first end point intersecting with the first folding line 1211, and the second cutting edge 1222 has a second end point intersecting with the second folding line 1221. It can be seen that, in the width direction of the battery cell 1, the first cutting edge 1212 is located on the extension line of the second folding line 1221 or on the side close to the package body 11, and in the length direction of the battery cell 1, the second cutting edge 1222 is located on the extension line of the first folding line 1211 or on the side close to the package body 11, so that the cutting removal area includes the edge sealing overlapping area. Alternatively, the first folding line 1211, the second folding line 1221, the first cutting edge 1212 and the second cutting edge 1222 intersect at the first vertex, or the extension line of the first folding line 1211 and the extension line of the second folding line 1221 intersect at the first vertex.

[0065] If the cutting removal area is too small and cannot completely cut off the edge sealing overlapping area, the first folding part 121 and the second folding part 122 cannot be completely folded. If the cutting removal area is too large, the sealing of the sealing part 12 is unreliable, which can easily lead to sealing failure and the safety of the battery cell 1 cannot be guaranteed. In the extension direction of the first folding line 1211, the distance from the first end point to the first vertex is a1, and a1 satisfies: 0mm≤a1≤2.0mm. In the extension direction of the second folding line 1221, the distance from the second end point to the first vertex is a2, and a2 satisfies: 0mm≤a2≤2.0mm. Alternatively, a1 can be 0mm, 0.25mm, 0.5mm, 0.75mm, 1.0mm, 1.5mm, 2.0mm or a range formed by any two of them, and a2 can be 0mm, 0.25mm, 0.5mm, 0.75mm, 1.0mm, 1.5mm, 2.0mm or a range formed by any two of them.

[0066] The first cut edge 1212 extends to a first outer boundary line 1214, and an angle between the first cut edge 1212 and the first folding line 1211 is a1; the second cut edge 1222 extends to a second outer boundary line 1224, and an angle between the second cut edge 1222 and the second folding line 1221 is a2, wherein a1, a2 satisfy: 0° < a1≤ 90°, 0° < a2≤ 90°. In the embodiment of the present application, by setting a1, a2 ∈ (0°, 90°], the obstruction caused by the edge sealing overlapping area to the folding edge is eliminated. When a1, a2 are 0°, the cutting removal area is too large, and the effective sealing cannot be guaranteed. When a1, a2 are higher than the upper limit 90°, the edge sealing overlapping area is likely to be reserved, which may cause the first folding part 121 and the second folding part 122 to interfere with each other when being folded.

[0067] In some embodiments of the present application, the first cut edge 1212 and the second cut edge 1222 are arranged at intervals, so that the first folding part 121 and the second folding part 122 are arranged at intervals. The corner sealing part 123 has a first corner line 1231 connected between the first end point and the second end point. In this way, the first cut edge 1212, the first corner line 1231, the second cut edge 1222 together form the cutting boundary line mentioned above, and the first cut edge 1212, the first corner line 1231, the second cut edge 1222, the extension line of the second outer boundary line 1224 and the extension line of the first outer boundary line 1214 together define the cutting removal area.

[0068] Further, at least one of the first end point and the second end point is arranged at intervals from the first vertex. In a specific implementation, as shown in FIG. 3, the first end point and the second end point can be arranged at intervals from the first vertex. Alternatively, as shown in FIG. 5, which is a structural schematic diagram of a cutting removal area in an embodiment of the present application, the first end point and the second end point can be arranged at intervals from the first vertex, and the second end point coincides with the first vertex, at this time, the first corner line 1231 is on the extension line of the first folding line 1211. Alternatively, as shown in FIG. 6, which is another structural schematic diagram of a cutting removal area in an embodiment of the present application, the first end point coincides with the first vertex, and the second end point is arranged at intervals from the first vertex, at this time, the first corner line 1231 is on the extension line of the second folding line 1221.

[0069] It can be understood that if the cutting boundary line has a bending angle, folding the first folding part 121 and the second folding part 122 is easy to cause stress concentration of the bending angle, and then cause tearing, affecting the sealing effect. In an optional embodiment of the present application, the first cutting edge 1212, the second cutting edge 1222 and the first cutting corner line 1231 are collinear, that is, the cutting boundary line is a straight line segment, and the cutting removal area is a triangle. In this way, the sealing part 12 can be formed by one cutting, which is simple and easy to operate, and is conducive to improving the overall production efficiency, and in addition, this design can also avoid the bending angle in the cutting boundary line. In some other embodiments, the first cutting edge 1212, the second cutting edge 1222 and the first cutting corner line 1231 can also be connected at an included angle, and the stress concentration can be reduced by controlling the angle of the bending angle in the cutting boundary line or rounding the bending angle. Of course, the first cutting edge 1212, the second cutting edge 1222 and the first cutting corner line 1231 can also adopt a curved segment.

[0070] Based on the above embodiment, the minimum distance L from the first vertex to the first cutting corner line 1231 is 0mm≤L≤1.0mm. When L is less than 0mm, that is, the first vertex is located on the side of the first cutting corner line 1231 close to the packaging body 11, and the edge overlap area is not removed sufficiently, which will directly hinder the folding of the first folding part 121 and the second folding part 122, causing the packaging size of the packaging bag 10 to increase. When L is greater than 1.0mm, the cutting removal area is too wide, although it ensures the elimination of the edge overlap area, but increases the risk of sealing failure. In this case, in order to ensure the sealing efficiency of the sealing part 12, the battery cell 20 needs to be cut too much, which will reduce the capacity of the battery cell 1, which is not conducive to the improvement of the energy density.

[0071] In some other embodiments of the present application, the first cutting edge 1212 and the second cutting edge 1222 intersect at the first vertex, that is, the first endpoint, the second endpoint and the first vertex coincide. At this time, the first cutting edge 1212 and the second cutting edge 1222 form a cutting boundary line, and the extension line of the first cutting edge 1212, the second cutting edge 1222, the second outer boundary line 1224 and the extension line of the first outer boundary line 1214 together define a cutting removal area. As shown in FIG. 7, FIG. 7 is a structure schematic view of another cutting removal area of an embodiment of the present application. As an option, by setting the first cutting edge 1212 and the second cutting edge 1222 collinear, the bending angle in the cutting boundary line reduces the risk of tearing of the sealing part 12, wherein the cutting removal area is a triangle. In particular, in the embodiment in which the first endpoint, the second endpoint and the first vertex coincide, the first cutting corner line 1231 with a length of 0mm can be formed between the first endpoint and the second endpoint, and the minimum distance L from the first vertex to the first cutting corner line 1231 is 0mm.

[0072] In an embodiment of the present application, the first inner boundary line 1213 and the second inner boundary line 1223 are connected and intersect at a fourth end point. The distance from the fourth end point to the cutting boundary line is B, and to ensure the sealing effect, B satisfies: 1.2mm≤B≤2.0mm. As shown in FIG. 8, which is a structural schematic diagram of a corner sealing portion 123 according to an embodiment of the present application, based on the above embodiment, the line connecting the fourth end point and the first end point is defined as a first demarcation line 410, and the line connecting the fourth end point and the second end point is defined as a second demarcation line 420. Among them, the part of the sealing portion 12 between the two first demarcation lines 410 forms a first folding portion 121, and the part of the sealing portion 12 on the side away from the first folding portion 121 of the second demarcation line 420 forms a second folding portion 122. Further, the first end point and the second end point are arranged in a spaced manner, and the first demarcation line 410, the second demarcation line 420, and the first corner cutting line 1231 are sequentially connected and enclosed to form the corner sealing portion 123. In particular, if the first end point coincides with the second end point, that is, the first demarcation line 410 coincides with the second demarcation line 420, then the sealing portion 12 is composed of the first folding portion 121 and the second folding portion 122.

[0073] It should be noted that in the scheme in which the first inner boundary line 1213 and the second inner boundary line 1223 intersect at the fourth end point, to ensure the effective sealing width, the distance s1 between the first inner boundary line 1213 and the first folding line 1211, and the distance s2 between the second inner boundary line 1223 and the second folding line 1221, both need to be set to a large value. Although this scheme can achieve the folding and fixing of the first folding portion 121 and the second folding portion 122, it is difficult to achieve the optimal packaging size of the packaging bag 10.

[0074] In an alternative embodiment of the present application, the inner edge of the sealing portion 12 corresponding to the cutting boundary line is extended inward to ensure the sealing width of the sealing portion 12. The corner sealing portion 123 further comprises an inner corner boundary line 1232 connected between the first inner boundary line 1213 and the second inner boundary line 1223. By setting the inner corner boundary line 1232, the inner corner of the sealing portion 12 is extended inward to ensure that the corner sealing portion 123 has sufficient sealing width to form a barrier between the packaging body 11 and the external environment.

[0075] Specifically, the minimum distance between the inner corner boundary line 1232 and the cutting boundary line is T, and to ensure the sealing reliability of the corner sealing portion 123, 1.2mm≤T≤2.4m. Alternatively, T can be 1.2mm, 1.4mm, 1.6mm, 1.8mm, 2.0mm, 2.4mm, or a range formed by any two of them.

[0076] The inner corner boundary line 1232 is spaced apart from the first cutting edge 1212 and the second cutting edge 1222. In a direction perpendicular to the first cutting edge 1212, the minimum distance from the inner corner boundary line 1232 to the first cutting edge 1212 is T2, i.e. the point on the inner corner boundary line 1232 closest to the first cutting edge 1212 has a minimum distance T2 to the first cutting edge 1212. In order to ensure the sealing reliability of the sealing portion 12, T2 satisfies: 1.2mm≤T2≤2.4mm. In a direction perpendicular to the second cutting edge 1222, the minimum distance from the inner corner boundary line 1232 to the second cutting edge 1222 is T3, i.e. the point on the inner corner boundary line 1232 closest to the second cutting edge 1222 has a minimum distance T3 to the second cutting edge 1222. In order to ensure the sealing reliability of the sealing portion 12, T3 satisfies: 1.2mm≤T3≤2.4mm.

[0077] Further, if the cutting boundary line further comprises a first corner cutting line 1231, the inner corner boundary line 1232 is spaced apart from the first corner cutting line 1231. Alternatively, the inner corner boundary line 1232 is parallel to the first corner cutting line 1231, and the minimum distance between the inner corner boundary line 1232 and the first corner cutting line 1231 is T1. In order to ensure the sealing reliability of the corner sealing portion 123, 1.2mm≤T1≤2.4mm. Alternatively, T1 can be 1.2mm, 1.4mm, 1.6mm, 1.8mm, 2.0mm, 2.4mm or any range formed by any two of them. It should be noted that the inner corner boundary line 1232 and the first corner cutting line 1231 are designed to be parallel in an ideal state, but considering the machining precision and slight deviation in actual application, the parallelism between the two allows a tolerance range of ±5°. When there is a parallelism tolerance between the inner corner boundary line 1232 and the first corner cutting line 1231, the distance should be measured in a direction perpendicular to the first corner cutting line 1231.

[0078] Referring to FIG. 9-10, FIG. 9 is a schematic structural view of another corner sealing portion 123 according to an embodiment of the present application, and FIG. 10 is a schematic structural view of another corner sealing portion 123 according to an embodiment of the present application. In some embodiments, the inner corner boundary line 1232 intersects the first inner boundary line 1213 at a fifth end point, and a line connecting the first end point and the fifth end point defines a third boundary line 430. The inner corner boundary line 1232 intersects the second inner boundary line 1223 at a sixth end point, and a line connecting the second end point and the sixth end point defines a fourth boundary line 440. In the sealing portion 12, a portion between the two third boundary lines 430 forms a first folding portion 121, and a portion of the sealing portion 12 on a side of the fourth boundary line 440 away from the first folding portion 121 forms a second folding portion 122. Further, if the first end point and the second end point are spaced apart, the third boundary line 430, the inner corner boundary line 1232, the fourth boundary line 440, and the first corner line 1231 are sequentially connected and enclosed to form the corner sealing portion 123. If the first end point and the second end point coincide, the third boundary line 430, the inner corner boundary line 1232, and the fourth boundary line 440 are sequentially connected and enclosed to form the corner sealing portion 123.

[0079] In an embodiment of the present application, if the sealing portion 12 has an inner corner boundary line 1232 and the packaging body 11 has a corner corresponding to the inner corner boundary line 1232, the battery cell monomer 20 needs to be cut in order to be smoothly accommodated in the inner space of the packaging body 11. Specifically, the battery cell monomer 20 has a first outer edge 21 and a second outer edge 22 arranged at an included angle, and the battery cell monomer 20 also has a second corner line 23 arranged corresponding to a first vertex, and the two ends of the second corner line 23 are opposite to the first outer edge 21 and the second outer edge 22, respectively. The extension line of the first outer edge 21, the extension line of the second outer edge 22, and the second corner line 23 define a battery cell corner cutting area. The included angle between the second corner line 23 and the first outer edge 21 is β, and β satisfies: 0°<β<90°. Optionally, β can be 45°.

[0080] In the thickness direction of the battery cell 1, the projection area of the battery cell corner cutting area is M, and 0.10mm 2 ≤M≤6.31mm 2 If M<0.10mm 2 , the battery cell corner cutting area is too small, and after the battery cell monomer 20 is packaged by the packaging bag 10, the corner of the battery cell monomer 20 is too close to the outer boundary line of the sealing portion 12, which cannot ensure effective sealing after cutting. If M>6.31mm 2 , the area of the battery cell corner cutting area is too large, which reduces the area of the cathode tab in the battery cell monomer 20 and greatly reduces the capacity, which may lead to a decrease in the energy density of the battery cell 1.

[0081] In specific embodiments, the cutting shape of the battery cell 20, the shape of the packaging body 11, and the cutting boundary line of the packaging bag 10 are matched and designed by the skilled person to ensure that the battery cell 20 can be accommodated in the packaging body 11, ensure that the sealing performance of the sealing part 12 is good after cutting, and the first folding part 121 and the second folding part 122 can be folded. In specific embodiments, the shape of the packaging body 11 is adjusted and controlled by stamping forming process parameters.

[0082] Optionally, the packaging bag 10 comprises a packaging film, the packaging film is wound from one side of the battery cell 20 to the other side of the battery cell 20, and after folding the film, a packaging body 11, a first folding part 121 and two second folding parts 122 are formed, and the battery cell 20 is arranged in the internal space of the packaging body 11.

[0083] The positive electrode tab, the negative electrode tab, the separator, the positive electrode tab, the negative electrode tab, and the electrolyte in the embodiments of the present application are not particularly limited, and various elements known in the art can be used as the above-mentioned elements of the battery cell 1.

[0084] The embodiments of the present application also provide a secondary battery, which comprises a housing and the battery cell 1 as described above, and the battery cell 1 is arranged in the internal space of the housing.

[0085] In specific embodiments, in the case where the size of the battery cell 20 is determined, the above-mentioned packaging method of the embodiments of the present application can reduce the size of the secondary battery after packaging, make the structure of the secondary battery more compact, and realize the improvement of energy density. Optionally, in the case where the size of the secondary battery is determined, the above-mentioned packaging method of the embodiments of the present application can reduce the size occupied by the top sealing edge and the side sealing edge, and then the size of the internal battery cell 20 can be increased, the capacity of the secondary battery can be increased, and the energy density can be improved.

[0086] The embodiments of the present application also provide an electronic device comprising the secondary battery in any of the foregoing embodiments. Therefore, the electronic device provided by the present application has good use performance.

[0087] The electronic device is not particularly limited in kind, and can be any electronic device known in the art. In some embodiments, the electronic device can include, but is not limited to, a notebook computer, a pen input computer, a mobile computer, an electronic book player, a portable telephone, a portable facsimile machine, a portable copying machine, a portable printer, a head-mounted stereo headphone, a video recorder, a liquid crystal television, a portable cleaner, a portable CD player, a mini disc, a transceiver, an electronic organizer, a calculator, a memory card, a portable audio recorder, a radio, a backup power supply, a motor, an automobile, a motorcycle, a power-assisted bicycle, a bicycle, a lighting appliance, a toy, a game machine, a timepiece, a power tool, a flash, a camera, a household large storage battery, and a lithium ion capacitor, etc.

[0088] The present application will be further described below with reference to the example of the lithium ion battery cell 1 and in combination with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and are not used to limit the scope of the present application.

[0089] The performance of the lithium ion battery is tested by the following method in each embodiment and each comparative example in the present application:

[0090] (1) Energy density test

[0091] The lithium ion battery is discharged to the terminal voltage under the standard test condition at a constant current of 0.2C, and is left for 5 min. The lithium ion battery is charged under the standard test condition at a constant current of 1C, and when the terminal voltage of the lithium ion battery reaches the charge limit voltage, it is changed to constant voltage charging until the charging current is less than or equal to 0.02C, and the longest charging time is not greater than 4h, the charging is stopped, and after the charging is completed, it is left for 5 min. The lithium ion battery is discharged under the standard test condition at 0.2C until the terminal voltage of the lithium ion battery reaches 3.0V, and the discharge capacity I in the discharge process is recorded.

[0092] The energy density of the lithium ion battery is calculated according to the discharge capacity I and the volume V of the lithium ion battery: VED=I / V.

[0093] (2) High temperature and high humidity test

[0094] The lithium ion battery was discharged to the terminal voltage under the standard test condition at a constant current of 0.2C, and was left for 5 min. The lithium ion battery was charged under the standard test condition at a constant current of 1C, and when the terminal voltage of the lithium ion battery reached the charge limit voltage, the charging was changed to constant voltage charging until the charging current was less than or equal to 0.02C, and the longest charging time was not more than 4h, and the charging was stopped. After the charging was completed, the above process was cycled twice, and the initial thickness value d0 of the lithium ion battery after the second full charging was tested. The fully charged lithium ion battery was left to stand for 7 days under the condition that the temperature was 60℃±2℃ and the humidity was 90%~95%. The fully charged lithium ion battery was left to stand for 2h under the condition of room temperature, and the cooling thickness d1 of the lithium ion battery was tested. According to the initial thickness value and the cooling thickness value of the lithium ion battery, the thickness change rate of the lithium ion battery in the high temperature and high humidity test was calculated: μ=(d1-d0) / d0.

[0095] The embodiments of the present application simulate the state of the lithium ion battery after long-term use through the high temperature and high humidity test, and the sealing performance of the lithium ion battery is characterized according to the thickness change rate of the lithium ion battery in the high temperature and high humidity test, wherein μ≤10%, and the sealing performance of the lithium ion battery is qualified. The smaller μ is, the better the sealing performance is.

[0096] In the embodiments and the comparative examples of the present application, the lithium ion battery was prepared by the following method, and the performance of the lithium ion battery was tested:

[0097] Preparation method of lithium ion battery

[0098] Comparative example 1-1

[0099] (1) Preparation of positive electrode sheet

[0100] The positive electrode active material lithium cobaltate LiCoO2, the conductive agent conductive carbon black, and the binder polyvinylidene fluoride PVDF were mixed in a mass ratio of 97.9:0.9:1.2, N-methyl pyrrolidone NMP was added as a solvent, and the mixture was uniformly stirred under the action of a vacuum stirrer to obtain a positive electrode slurry with a solid content of 75wt%. The positive electrode slurry was uniformly coated on one surface of an aluminum foil positive electrode current collector with a thickness of 9μm, and was dried at 85℃ and cold-pressed to obtain a positive electrode with a single-side coated positive electrode material layer with a thickness of 95μm. Then, the above steps were repeated on the other surface of the aluminum foil to obtain a positive electrode with a double-side coated positive electrode material layer. After cutting and welding the positive electrode tab aluminum tab, a positive electrode sheet with a specification of 74mm×851mm was obtained, and the compaction density of the positive electrode material layer of the positive electrode sheet was 4.20g / cm 3 .

[0101] (2) Preparation of negative electrode sheet

[0102] The negative active material artificial graphite, the binder styrene-butadiene rubber SBR, and the thickening agent sodium carboxymethyl cellulose CMC were mixed in a mass ratio of 97.4:1.4:1.2, and then deionized water was added as a solvent. The mixture was stirred uniformly in a vacuum stirrer to obtain a negative electrode slurry with a solid content of 50 wt%. The negative electrode slurry was uniformly coated on one surface of a negative electrode current collector copper foil with a thickness of 10 μm, and the negative electrode was obtained by drying at 85°C and cold pressing to obtain a single-side coated negative electrode material layer with a thickness of 130 μm. Then, the above steps were repeated on the other surface of the copper foil to obtain a double-side coated negative electrode. After cutting and welding the negative electrode tabs, a negative electrode tab with a size of 76 mm x 867 mm was obtained, and the compacted density of the negative electrode material layer of the negative electrode tab was 1.80 g / cm3. 3 .

[0103] (3) Preparation of the separator film

[0104] The porous base material layer was a 9 μm thick polypropylene film.

[0105] (4) Preparation of the electrolyte

[0106] In an argon atmosphere glove box with a water content of less than 10 ppm, ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl propionate (EP), and propyl propionate (PP) were mixed in a mass ratio of 1:1:1:1:1 to obtain a base solvent. Lithium hexafluorophosphate (LiPF6) was dissolved in the above non-aqueous solvent to obtain an electrolyte. The mass percentage of LiPF6 in the electrolyte was 12.5% based on the total mass of the electrolyte.

[0107] (5) Assembly of the lithium ion battery

[0108] The positive electrode tabs were installed on the positive electrode, and the negative electrode tabs were installed on the negative electrode. The positive electrode with the installed positive electrode tabs, the separator film, and the negative electrode with the installed negative electrode tabs were sequentially stacked in order, with the separator film between the positive electrode and the negative electrode to play a separating role, and the cell monomer 20 was obtained by winding.

[0109] The cell monomer 20 was placed in a packaging film, and after removing the water at 80°C, the above electrolyte was injected and packaged. Then, the lithium ion battery was obtained by the processes of standing, formation (0.2C constant current charging to 3.5V, and then 1C constant current charging to 3.9V), capacity, degassing, and edge cutting. After the edge folding of the lithium ion battery, the length and width dimensions of the lithium ion battery were as shown in Table 1. The side seal of the lithium ion battery was folded, and the top seal was not folded. At this time, the width of the top seal was 2.5 mm.

[0110] Examples 1-1 to 4-7 and Comparative Examples 1-2 to 4-2

[0111] The difference from Comparative Example 1 includes that, in the assembly of the lithium ion battery, the cell monomer 20 is cut, placed in the packaging film, after removing water at 80°C, the above-mentioned electrolyte is injected and packaged, and then the lithium ion battery is obtained after the processes of standing, formation (0.2C constant current charging to 3.5V, and then 1C constant current charging to 3.9V), capacity, degassing, edge cutting, etc., the packaging bag 10 is cut along the preset cutting boundary line to form the first folding part 121 and the second folding part 122 which are folded and fixed on the side of the packaging main body 11, so as to complete the packaging of the lithium ion battery, wherein the length and width dimensions of the packaged lithium ion battery are consistent with those in Comparative Example 1, and the size of the cell monomer 20 is adjusted adaptively.

[0112] Example 4-5 to Example 4-7, Comparative Example 4-3-Comparative Example 4-4

[0113] The difference from Comparative Example 1 includes that, in the assembly of the lithium ion battery, after removing water at 80°C, the above-mentioned electrolyte is injected and packaged, and then the lithium ion battery is obtained after the processes of standing, formation (0.2C constant current charging to 3.5V, and then 1C constant current charging to 3.9V), capacity, degassing, edge cutting, etc., the packaging bag 10 is cut along the preset cutting boundary line to form the first folding part 121 and the second folding part 122 which are folded and fixed on the side of the packaging main body 11, so as to complete the packaging of the lithium ion battery, wherein the length and width dimensions of the packaged lithium ion battery are consistent with those in Comparative Example 1, and the size of the cell monomer 20 is adjusted adaptively.

[0114] The performance test results of the lithium ion batteries prepared in Comparative Example 1-1 to Comparative Example 1-3 and Example 1-1 to Example 1-3 are shown in Table 1.

[0115] Table 1

[0116] As can be seen from Table 1, Example 1-1 to Example 1-3, Comparative Example 1-1 to Comparative Example 1-3, the included angle γ between the first cutting edge 1212 and the second cutting edge 1222 satisfies: 90°≤γ≤180°, the energy density of the prepared lithium ion battery is optimized, and the sealing performance is good, when γ is less than the lower limit 90°, the top sealing edge and the side sealing edge of the lithium ion battery still interfere, the top sealing edge cannot be effectively folded, and the energy density cannot be improved, when γ exceeds the upper limit 180°, the sealing performance of the lithium ion battery is not good.

[0117] The performance test results of the lithium ion batteries prepared in Comparative Example 1-1, Comparative Example 2-1 to Comparative Example 2-2, Example 2-1 to Example 2-10 are shown in Table 2.

[0118] Table 2

[0119] As can be seen from Table 2, Comparative Example 1-1, Examples 2-1 to 2-5, and Comparative Example 2-1, the distance a1 from the first end point to the first vertex satisfies: 0mm≤a1≤2.0mm, and the energy density of the lithium ion battery is optimized, and when a1 exceeds the upper limit of 2.0mm, the energy density of the lithium ion battery is reduced.

[0120] As can be seen from Table 2, Comparative Example 1-1, Examples 2-6 to 2-10, and Comparative Example 2-2, the distance a2 from the second end point to the first vertex satisfies: 0mm≤a2≤2.0mm, and the energy density of the lithium ion battery is optimized, and when a1 exceeds the upper limit of 2.0mm, the energy density of the lithium ion battery is reduced.

[0121] The performance test results of the lithium ion batteries prepared in Comparative Example 1-1, Comparative Examples 3-1 to 3-2, and Examples 3-1 to 3-3 are shown in Table 2.

[0122] Table 3

[0123] As can be seen from Table 2, Comparative Example 1-1, Comparative Examples 3-1 to 3-2, and Examples 3-1 to 3-3, compared with the scheme without cutting the aluminum plastic film and the single battery, the minimum distance L from the first vertex to the first tangent line 1231 satisfies: 0mm≤L≤1.0mm, and the energy density of the lithium ion battery is optimized, and when L exceeds the upper limit of 1.0mm, the energy density of the lithium ion battery is greatly reduced, and even the energy density is reduced.

[0124] The performance test results of the lithium ion batteries prepared in Comparative Example 1-1, Comparative Examples 4-1 to 4-4, and Examples 4-1 to 4-7 are shown in Table 2.

[0125] Table 4

[0126] As can be seen from Table 4, Comparative Example 1-1, Comparative Examples 4-1 to 4-2, and Examples 4-1 to 4-4, when the aluminum plastic film packaging bag 10 and the single battery 20 are cut at the same time, the minimum distance T1 from the inner corner boundary line 1232 to the first tangent line 1231 satisfies: 1.2mm≤T1≤2.4mm, and the energy density of the lithium ion battery is optimized, and the sealing performance is good. When T1 exceeds the upper limit range of 2.4mm, the energy density of the lithium ion battery is reduced, and when T1 is less than the lower limit range of 1.2mm, the sealing performance of the lithium ion battery is poor.

[0127] It can be seen from the comparative example 1-1, the comparative example 4-3 to the comparative example 4-4, the example 4-5 to the example 4-7 in Table 4 that when only the cutting of the packaging bag 10 of the aluminum plastic film is performed, the distance B from the fourth end point to the cutting boundary line satisfies 1.2 mm≤B≤2.0 mm, the energy density of the lithium ion battery is optimized, and the sealing performance is good. When B exceeds the upper limit range 2.0 mm, the energy density of the lithium ion battery decreases, and when B is less than the lower limit range 1.2 mm, the sealing performance of the lithium ion battery is poor.

[0128] The same or similar reference numerals in the drawings of the embodiments correspond to the same or similar components; in the description of the present application, it is understood that if the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right" and the like are based on the orientations or positional relationships shown in the drawings, they are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the terms describing the positional relationships in the drawings are only used for exemplary illustration, and cannot be understood as a limitation of the present patent, for those skilled in the art, the specific meanings of the above terms can be understood according to the specific circumstances.

[0129] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An electric cell, wherein, The package bag comprises a package body and a sealing part connected to the package body; The sealing part comprises a first folding part and a second folding part, the first folding part has a first folding line, the first folding part further comprises a first cut edge towards the second folding part, the first cut edge intersects with the first folding line at a first end point; the second folding part has a second folding line, the second folding part further comprises a second cut edge towards the first folding part, the second cut edge intersects with the first folding line at a second end point; the first folding line and the second folding line are arranged at an included angle, and the included angle between the first cut edge and the second cut edge is γ, 90°≤γ≤180°; Wherein, the first folding line, the second folding line, the first cut edge and the second cut edge intersect at a first vertex, or the extension line of the first folding line intersects with the extension line of the second folding line at the first vertex.

2. The electric cell of claim 1, wherein, In the extension direction of the first folding line, the distance from the first end point to the first vertex is a1, and in the extension direction of the second folding line, the distance from the second end point to the first vertex is a2, 0≤a1≤2.0mm, 0≤a2≤2.0mm.

3. The electric cell of claim 1, wherein, One end of the first cut edge extends to the outer edge of the first folding part, and the included angle between the first cut edge and the first folding line is α1; one end of the second cut edge extends to the outer edge of the second folding part, and the included angle between the second cut edge and the second folding line is α2; the battery cell satisfies at least one of the following conditions: (1)0°＜α1≤90°； (2)0°＜α2≤90°。 4. The electric cell of claim 1, wherein, At least one of the first end point and the second end point is arranged apart from the first vertex, and the sealing part has a first corner line connected between the first end point and the second end point; the battery cell satisfies at least one of the following conditions: (1) The minimum distance from the first vertex to the first corner line is L, 0≤L≤1.0mm; (2) The included angle between the first folding line and the second folding line is θ, 85°≤θ≤95°.

5. The electric cell of claim 4, wherein, The inner edge of the first folding part and the inner edge of the second folding part intersect at a fourth end point, and the minimum distance from the fourth end point to the first corner line is B, 1.2mm≤B≤2.0mm.

6. The electric cell of claim 4, wherein, The sealing part further has an inner corner boundary line connected between the inner edge of the first folding part and the inner edge of the second folding part, and the inner corner boundary line is arranged apart from the first corner line.

7. The battery cell according to claim 6, wherein The inner corner boundary line is parallel to the first corner line; The minimum distance between the inner corner boundary line and the first corner line is T1, 1.2mm≤T1≤2.4mm.

8. The electric cell of claim 6, wherein, The minimum distance between the inner corner boundary line and the first cut edge is T2, T2 satisfies: 1.2mm≤T2≤2.4mm; The minimum distance between the inner corner boundary line and the second cut edge is T3, T3 satisfies: 1.2mm≤T3≤2.4mm.

9. The electric cell of claim 1, wherein, The battery cell further comprises a battery cell monomer arranged in the internal space of the package body, and the battery cell monomer has a second corner line corresponding to the first vertex; The second tangent line intersects the first outer edge and the second outer edge of the battery cell monomer at two ends, respectively, and the extension line of the first outer edge, the extension line of the second outer edge and the second tangent line define a battery cell tangent corner area, the projection area of the battery cell tangent corner area in the thickness direction of the battery cell is M, 0.10mm 2 ≤M≤6.31mm 2 .

10. The battery cell of any one of claims 1-9, wherein, the first fold line is located between the inner edge and the outer edge of the first fold portion; in a direction perpendicular to the first fold line, the distance from the first fold line to the inner edge of the first fold portion is s1, 0.1 mm≤s1≤1.0 mm, and the distance between the inner edge and the outer edge of the first fold portion is k1, 1.0 mm≤k1≤4.0 mm; the sealing portion has a second fold line located between the inner edge and the outer edge of the second fold portion; in a direction perpendicular to the second fold line, the distance from the second fold line to the inner edge of the second fold portion is s2, 0.1 mm≤s2≤1.0 mm, and the distance between the inner edge and the outer edge of the second fold portion is k2, 0.6 mm≤k2≤4.0 mm.

11. The battery cell of any one of claims 1-9, wherein, the first fold portion is located on one side of the package body in the length direction of the battery cell, and the second fold portion is located on one side of the package body in the width direction of the battery cell, the length direction, the width direction, and the thickness direction of the battery cell being perpendicular to each other; the battery cell further comprises a tab connected to the first fold portion and extending from the first fold portion.

12. The electric cell of claim 11, wherein, the package body has two first side surfaces located opposite each other in the length direction of the battery cell, and two second side surfaces located opposite each other in the width direction of the battery cell; the first fold portion has a first folded edge located between the outer edge thereof and the first fold line, and a first straight edge located between the inner edge thereof and the first fold line, and the second fold portion has a second folded edge located between the outer edge thereof and the second fold line, and a second straight edge located between the inner edge thereof and the second fold line; wherein the first folded edge is folded relative to the first straight edge and connected to one of the first side surfaces, and the second folded edge is folded relative to the second straight edge and connected to one of the second side surfaces.

13. The electric cell of claim 3, wherein, the battery cell further comprises a battery cell monomer, the package bag comprises a packaging film, the packaging film is wrapped from one side of the battery cell monomer to the other side of the battery cell monomer, and after folding and film folding, one package body, one first fold portion, and two second fold portions are formed, and the battery cell monomer is arranged in the internal space of the package body.

14. A secondary battery, wherein, comprising: a housing; and the battery cell of any one of claims 1-13 is arranged in the internal space of the housing. comprising the secondary battery of claim 14.

15. An electronic device, wherein, ​

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