Battery and battery manufacturing method

Abstract

The invention discloses a battery and a battery manufacturing method, and the battery comprises a housing which is provided with a storage cavity; the battery cell is arranged in the storage cavity, the battery cell comprises a straight part and a bent part, two ends of the bent part are respectively connected to the two straight parts, a groove is formed in the bent part, and the groove is used for accommodating electrolyte. The battery cell comprises the straight part and the bent part, the bent part is formed after the pole piece is bent, the bent part is provided with the groove for accommodating the electrolyte, in the prior art, the bent part of the battery cell is not provided with the groove, so that more electrolyte cannot be accommodated, and the problem of lithium precipitation of the battery is caused; and even if the bent part is extruded, the electrolyte can be effectively stored in the groove, so that the problem of lithium precipitation of the battery can be effectively avoided. Specifically, the battery can effectively avoid lithium precipitation.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a battery and a battery manufacturing method. Background Art

[0002] In the related art, the battery includes a battery cell and a shell, and the battery cell is arranged inside the shell. The battery cell can be formed by stacking the positive electrode sheet and the negative electrode sheet, or by stacking the positive electrode sheet and then winding the positive electrode sheet. Among them, some areas of the positive electrode sheet and the negative electrode sheet will be bent when winding. Specifically, during the charging and discharging process of the battery cell, due to the existence of factors such as winding tension and expansion, the electrolyte retained in the bending area of ​​the electrode sheet will be squeezed, resulting in less electrolyte in the bending area, so that the battery will experience lithium deposition. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a battery that can effectively avoid the occurrence of lithium plating.

[0004] The invention also provides a battery manufacturing method.

[0005] A battery according to a first aspect of the present invention comprises:

[0006] A housing having a storage cavity;

[0007] A battery cell is arranged in the storage cavity, and the battery cell includes a straight portion and a curved portion, wherein two ends of the curved portion are respectively connected to the two straight portions, wherein a groove is arranged on the curved portion, and the groove is used to accommodate electrolyte.

[0008] The battery according to the embodiment of the present invention has at least the following beneficial effects: the battery cell includes a straight portion and a curved portion, the curved portion is formed after the pole piece is bent, and the curved portion has a groove for accommodating electrolyte. In the prior art, the curved portion of the battery cell is not provided with a groove, so it cannot accommodate more electrolyte, which will cause the battery to have the problem of lithium deposition. In the present application, after the curved portion is provided with a groove, even if the curved portion is squeezed, the electrolyte will be effectively stored in the groove, so that the battery can effectively avoid the problem of lithium deposition. Specifically, the battery can effectively avoid the situation of lithium deposition.

[0009] According to some embodiments of the battery of the present invention, the bending portion has a plurality of first slot columns and a second slot column, each of the first slot columns and the second slot column includes a plurality of the grooves arranged along a first direction, and along a second direction, the first slot columns and the second slot columns are alternately arranged, and the first direction is perpendicular to the second direction.

[0010] In the battery according to some embodiments of the present invention, along the second direction, the first slot columns and the second slot columns are staggered.

[0011] In batteries according to some embodiments of the present invention, a distance A between the first slot array and the second slot array is staggered, and 0.3 mm≤A≤9 mm.

[0012] In batteries according to some embodiments of the present invention, a distance between a center line of the first slot column and a center line of the second slot column in the second direction is B, and 0.6 mm≤B≤10 mm.

[0013] In batteries according to some embodiments of the present invention, the depth of the groove is C, 3um≤C≤15um.

[0014] According to some embodiments of the battery of the present invention, there are multiple curved portions, the arc length of each curved portion is different, and the arc length of the curved portion gradually increases from the straight portion to the curved portion, wherein the grooves of two adjacent curved portions are staggered in the width direction of the battery cell.

[0015] The battery manufacturing method according to the second aspect of the present invention comprises the following steps:

[0016] A pole piece is prepared;

[0017] Embossing on the pole piece so that a groove is formed on the pole piece;

[0018] The pole pieces are wound to form a battery core.

[0019] The battery manufacturing method according to the embodiment of the present invention has at least the following beneficial effects: after embossing on the pole piece, a groove will be formed on the pole piece, that is, there will be a groove on the battery cell. In the prior art, there is no groove on the battery cell, so the bend of the battery cell cannot accommodate more electrolyte, which will cause the battery to have the problem of lithium precipitation. In the present application, after the groove is set on the battery cell, the groove can accommodate the electrolyte, so even if the battery cell is squeezed, the electrolyte will be effectively stored in the groove, and the battery can effectively avoid the problem of lithium precipitation. Specifically, the battery manufactured by the battery manufacturing method can effectively avoid the situation of lithium precipitation.

[0020] According to some embodiments of the battery manufacturing method of the present invention, the battery cell includes a straight portion and a curved portion, and both ends of the curved portion are respectively connected to the two straight portions. The battery manufacturing method also includes a step of flattening the grooves on the straight portions.

[0021] According to some embodiments of the battery manufacturing method of the present invention, the battery manufacturing method further includes the steps of preparing the pole piece, welding the pole lug to the pole piece, and avoiding the area where the pole piece and the pole lug are connected when embossing the pole piece.

[0022] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0024] Figure 1 is a schematic diagram of a battery cell in a battery according to a first embodiment of the present invention;

[0025] Figure 2 is a schematic diagram of a battery cell in a battery according to a second embodiment of the present invention;

[0026] Figure 3 is a schematic cross-sectional view of a groove in a battery according to a first embodiment of the present invention;

[0027] Figure 4 is a schematic cross-sectional view of a groove in a battery according to a second embodiment of the present invention;

[0028] Figure 5 Schematic diagram of a pole piece in a battery in some embodiments of the present invention;

[0029] Figure 6 FIG. 4 is a schematic flow chart of a battery manufacturing method according to some embodiments of the present invention.

[0030] Reference numerals:

[0031] The battery cell 100 , the curved portion 200 , the groove 300 , the first slot row 400 , the second slot row 500 , the straight portion 600 , the electrode sheet 700 , the positive electrode sheet 710 , the negative electrode sheet 720 , and the separator 800 . DETAILED DESCRIPTION

[0032] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0033] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0034] In the description of the present invention, "several" means more than one, "many" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, and "above", "below", "within", etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0035] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0036] In the description of the present invention, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0037] In the related art, the battery includes a battery cell 100 and a shell, and the battery cell 100 is arranged inside the shell. The battery cell 100 can be formed by stacking the positive electrode sheet 710 and the negative electrode sheet 720, or the battery cell 100 can be formed by stacking the positive electrode sheet 710 and the negative electrode sheet 720 and then winding them. Among them, some areas of the positive electrode sheet 710 and the negative electrode sheet 720 will be bent when winding. Specifically, during the charging and discharging process of the battery cell 100, due to the existence of factors such as winding tension and expansion, the electrolyte retained in the bending area of ​​the electrode sheet 700 will be squeezed, resulting in less electrolyte in the bending area, so that the battery has lithium deposition. To this end, the present application proposes a battery and a battery manufacturing method.

[0038] Please refer to Figures 1 to 4In some embodiments, the battery includes a shell and a battery cell 100. The shell has a storage cavity. The shell mainly serves as the outer shell of the battery and plays a role in physically protecting the internal components of the battery. It can resist the influence of the external environment, such as mechanical damage, vibration, impact, etc., thereby protecting the battery from damage. The shell can be an aluminum-plastic film or a metal shell. The battery cell 100 is arranged in the storage cavity. The battery cell 100 includes a positive electrode sheet 710 and a negative electrode sheet 720, and a diaphragm 800 is provided between the positive electrode sheet 710 and the negative electrode sheet 720. The positive electrode sheet 710, the diaphragm 800 and the negative electrode sheet 720 are stacked and then wound to form the battery cell 100. Among them, the battery cell 100 includes a straight portion 600 and a curved portion 200. The two ends of the curved portion 200 are respectively connected to the two straight portions 600, that is, the two ends of a straight portion 600 are respectively connected to the two curved portions 200. When the positive electrode sheet 710 is unfolded, the curved portion 200 and the straight portion 600 are alternately arranged along the length direction of the positive electrode sheet 710. When the negative electrode sheet 720 is unfolded, the curved portion 200 and the straight portion 600 are alternately arranged along the length direction of the negative electrode sheet 720. Among them, a groove 300 is arranged on the curved portion 200, and the groove 300 is used to accommodate the electrolyte. The groove 300 arranged on the curved portion 200 can be specifically that the positive electrode sheet 710 has a groove 300, and the negative electrode sheet 720 does not have a groove 300, or that the negative electrode sheet 720 has a groove 300, and the positive electrode sheet 710 does not have a groove 300. For details, please refer to Figure 1 Alternatively, the positive electrode sheet 710 has a groove 300, the negative electrode sheet 720 has a groove 300, and the groove 300 on the negative electrode sheet 720 and the groove 300 on the positive electrode sheet 710 are staggered and do not overlap each other. For details, please refer to Figure 2 . Specifically, the battery cell 100 includes a straight portion 600 and a curved portion 200. The curved portion 200 is formed after the pole piece 700 is bent. The curved portion 200 has a groove 300 for accommodating electrolyte. In the prior art, the curved portion 200 of the battery cell 100 is not provided with a groove 300, so it cannot accommodate more electrolyte, which will cause the battery to have a lithium deposition problem. In the present application, after the curved portion 200 is provided with a groove 300, even if the curved portion 200 is squeezed, the electrolyte will be effectively stored in the groove 300, so that the battery can effectively avoid the problem of lithium deposition. Specifically, the battery can effectively avoid the occurrence of lithium deposition.

[0039] The groove 300 is described in detail below, wherein the shape of the groove 300 may be an oblong, rectangular, circular or elliptical shape, etc. The shape of the groove 300 is not specifically limited. The shape of the groove 300 may also be a combination of multiple shapes, such as a combination of a rectangle, a semicircle and an oblong. Specifically, the two ends of the rectangle are connected to two semicircles respectively, and an oblong is provided below the rectangle and the semicircle. In addition to the combination of a rectangle, a semicircle and an oblong, the shape of the groove 300 may also be a combination of a cylinder and two hemispheres, that is, the two hemispheres are located at the two ends of the cylinder. Among them, r represents the radius of the hemisphere, x represents the length of the cylinder, and y represents the protrusion height of the cylinder and the hemisphere. Among them, 0.3mm≤r≤4.0mm, 0≤x≤8.0mm, 0≤y≤0.2mm, and the circumference of the groove 300 is 7.8mm to 15mm. Further, the groove 300 may be formed by rolling the pole piece 700 with an embossing roller.

[0040] Furthermore, it is conceivable that the more the number of grooves 300 is, the more electrolyte can be accommodated, which can effectively avoid the situation where the electrolyte is scarce at the bend of the battery cell 100. The following is a detailed description of the arrangement of the plurality of grooves 300, please refer to Figure 5 , Figure 5 The arrangement of the grooves 300 when the pole piece 700 in the battery cell 100 is flattened is illustrated. In some embodiments, the curved portion 200 has a plurality of first groove columns 400 and a second groove column 500. The first groove column 400 and the second groove column 500 both include a plurality of grooves 300 arranged along a first direction. Along a second direction, the first groove column 400 and the second groove column 500 are alternately arranged, and the first direction is perpendicular to the second direction. Specifically, the first groove column 400 has a plurality of grooves 300, which can increase the volume for accommodating the electrolyte. Similarly, the second groove column 500 has a plurality of grooves 300, which can also increase the volume for accommodating the electrolyte. In this way, by providing a plurality of first groove columns 400 and a plurality of second groove columns 500, the curved portion 200 can be provided with a plurality of grooves 300, thereby effectively preventing the battery from lithium deposition.

[0041] For further information, please refer to Figure 5 In some embodiments, along the second direction, the first slot array 400 and the second slot array 500 are staggered. Specifically, after the first slot array 400 and the second slot array 500 are staggered, the space of the curved portion 200 can be fully utilized, so that the curved portion 200 is filled with grooves 300, so that the curved portion 200 has as many grooves 300 as possible, effectively ensuring that the grooves 300 can accommodate more electrolyte and avoid lithium deposition in the battery.

[0042] Furthermore, the groove 300 mentioned above can be formed by rolling the electrode sheet 700 with an embossing roller. The specific structure of the embossing roller is as follows: the body of the embossing roller is cylindrical, and a protrusion is provided on the cylindrical body, and the shape of the protrusion can be consistent with the shape of the groove 300. That is, the protrusion on the embossing roller can roll out the groove 300 on the electrode sheet 700, wherein the distance between the first groove row 400 and the second groove row 500 can be controlled by controlling the distance between two adjacent protrusions on the embossing roller. For details, please refer to Figure 5 In some embodiments, the distance between the first slot row 400 and the second slot row 500 is A, 0.3mm≤A≤9mm. The distance between the first slot row 400 and the second slot row 500 can be 0.3mm, 0.5mm, 1mm, 2mm, 5mm, 6mm, 8mm or 9mm. When the distance between the first slot row 400 and the second slot row 500 is greater than 9mm, this will result in low utilization of the curved portion 200, thereby reducing the number of grooves 300 and reducing the amount of electrolyte contained. When the distance between the first slot row 400 and the second slot row 500 is less than 0.3mm, due to the small spacing, this will increase the difficulty in processing the embossing roller, the manufacturing cost of the embossing roller is high, and further increase the manufacturing cost of the battery.

[0043] Furthermore, in addition to limiting the distance between the first slot array 400 and the second slot array 500, the distance between the center line of the first slot array 400 and the center line of the second slot array 500 in the second direction may also be limited. Figure 5 In some embodiments, the spacing between the center line of the first groove array 400 and the center line of the second groove array 500 in the second direction is B, 0.6mm≤B≤10mm. The spacing between the center line of the first groove array 400 and the center line of the second groove array 500 in the second direction may be 0.6mm, 0.8mm., 1mm, 2mm, 5mm, 6mm, 8mm, 9mm or 10mm. When the spacing between the center line of the first groove array 400 and the center line of the second groove array 500 in the second direction is less than 0.6mm, this will increase the difficulty of manufacturing the embossing roller, resulting in a high manufacturing cost of the embossing roller, further increasing the manufacturing cost of the battery. When the spacing between the center line of the first groove array 400 and the center line of the second groove array 500 in the second direction is greater than 10mm, since the distance between the first groove array 400 and the second groove array 500 in the second direction is too large, it will not be possible to fully utilize the space of the curved portion 200, which will reduce the number of grooves 300, and the amount of electrolyte that can be accommodated in the grooves 300 is small.

[0044] Further, in some embodiments, the depth of the groove 300 is C, 3um≤C≤15um. Specifically, the depth of the groove 300 may be 3um, 5um, 10um, 13um or 15um. Since the groove 300 can be formed by rolling the electrode 700 with an embossing roller, when the depth of the groove 300 is greater than 15um, the depth of the groove 300 is too large, which may cause the electrode 700 to be damaged by the embossing roller, such as the foil breaking. When the depth of the groove 300 is less than 3um, the depth of the groove 300 is too small, which may result in the groove 300 being able to accommodate a small amount of electrolyte.

[0045] Further, it is conceivable that the battery cell 100 is formed by winding the pole piece 700. The battery cell 100 includes a plurality of layers of wound pole pieces 700, the straight portion of the pole piece 700 may be the straight portion 600 of the battery cell 100, and the bent portion of the pole piece 700 may be the bent portion 200 of the battery cell 100. After the pole piece 700 is wound, the two adjacent layers of the bent portion 200 will fit together. In this case, the grooves 300 on the two adjacent bent portions 200 will overlap in the width direction, which may result in a situation where one groove 300 is located in another groove 300, thereby causing one groove 300 to squeeze out the electrolyte in the other groove 300. Therefore, please refer to Figure 1 In some embodiments, a plurality of curved portions 200 are provided, and the arc length of each curved portion 200 is different. From the straight portion 600 to the curved portion 200, the arc length of the curved portion 200 gradually increases. That is, the arc length of the curved portion 200 of each layer gradually increases, wherein the grooves 300 of two adjacent curved portions 200 are staggered in the width direction of the battery cell 100. Specifically, after the grooves 300 of two adjacent curved portions 200 are staggered in the width direction of the battery cell 100, the grooves 300 on the two adjacent curved portions 200 may not affect each other, reducing the situation where one groove 300 squeezes out the electrolyte in another groove 300, which can effectively increase the amount of electrolyte, thereby avoiding lithium deposition in the battery.

[0046] The battery is described above, and the manufacturing method of the battery is described below. It is conceivable that the battery manufacturing method can produce the battery in the above embodiment. Please refer to Figure 6 In some embodiments, the battery manufacturing method includes the following steps:

[0047] S100, producing a pole piece 700;

[0048] S200, embossing the pole piece 700 so that a groove 300 is formed on the pole piece 700;

[0049] S300 , winding the electrode sheet 700 to form the battery cell 100 .

[0050] Specifically, after embossing the pole piece 700, a groove 300 will be formed on the pole piece 700, that is, the battery cell 100 will have a groove 300. In the prior art, the battery cell 100 is not provided with a groove 300, so the bending part of the battery cell 100 cannot accommodate more electrolyte, which will cause the battery to have a lithium deposition problem. In the present application, after the groove 300 is provided on the battery cell 100, the groove 300 can accommodate the electrolyte, so even if the battery cell 100 is squeezed, the electrolyte will be effectively stored in the groove 300, and the battery can effectively avoid the problem of lithium deposition. Specifically, the battery manufactured by the battery manufacturing method can effectively avoid the occurrence of lithium deposition.

[0051] The specific process of "embossing the pole piece 700 so as to form the groove 300 on the pole piece 700" may be that after the pole piece 700 is manufactured, two embossing rollers are provided, the embossing rollers have protrusions, and the pole piece 700 is located between the two embossing rollers. Then, the embossing rollers are rolled, and the groove 300 is provided on the pole piece 700. Alternatively, after the pole piece 700 is manufactured, one surface of the pole piece 700 is first rolled by an embossing roller, and then the other surface of the pole piece 700 is rolled.

[0052] It should be added that the groove 300 on the pole piece 700 is formed by an embossing roller, that is, the pole piece 700 has a groove 300 which specifically means that the pole piece 700 includes a foil and an active material layer, and the active material layer is arranged on the foil. After the embossing roller presses the pole piece 700, the foil and the active material layer are jointly recessed upward or downward to form the groove 300.

[0053] Further, in some embodiments, the battery cell 100 includes a straight portion 600 and a curved portion 200, wherein the straight portion 600 specifically refers to a portion that is not bent after the pole piece 700 is wound, and the curved portion 200 specifically refers to a portion that is bent after the pole piece 700 is wound. The two ends of the curved portion 200 are respectively connected to two straight portions 600, and the two ends of one straight portion 600 are respectively connected to two curved portions 200. As mentioned above, a groove 300 is provided on the pole piece 700, that is, the groove 300 is provided on both the straight portion 600 and the curved portion 200, and the curved portion 200 is provided with the groove 300, which can be used to accommodate electrolyte, thereby effectively preventing lithium deposition in the battery. After the groove 300 on the straight portion 600 is flattened, the thickness of the battery cell 100 can be effectively prevented from being too large (the groove 300 will bulge relative to the surface of the pole piece 700, which will cause the thickness of the pole piece 700 to increase, thereby ultimately increasing the thickness of the battery cell 100). To this end, the battery manufacturing method also includes the step of flattening the groove 300 on the straight portion 600. Specifically, after the groove 300 on the straight portion 600 is flattened, the thickness of the battery cell 100 can be effectively avoided from being too large. Among them, the specific method of flattening the groove 300 on the straight portion 600 can be that after the battery cell 100 is manufactured, the battery cell 100 is placed in a battery casing and injected with electrolyte. Then, the groove 300 on the straight portion 600 is flattened by forming hot pressing. More specifically, the straight portion 600 of the battery cell 100 is clamped by two clamping plates, so that the groove 300 on the straight portion 600 is flattened. It should be added that after the groove 300 is set on the pole piece 700 by the embossing roller, not only can the lithium precipitation of the battery cell 100 be effectively avoided, but also the manufactured groove 300 does not need to reduce the amount of the active material layer, so the energy density of the battery is also high.

[0054] Furthermore, in some embodiments, the battery manufacturing method further includes the steps of preparing the pole piece 700, welding the pole lug to the pole piece 700, and avoiding the area where the pole piece 700 is connected to the pole lug when embossing the pole piece 700. Specifically, after the pole lug and the pole piece 700 are welded, adhesive tape can be used at the welding position of the pole lug and the pole lug to avoid the problem of short circuit in the battery cell 100. When embossing the pole piece 700, avoiding the area where the pole lug and the pole piece 700 are connected can effectively prevent the embossing roller from damaging the connection between the pole piece 700 and the pole lug, resulting in failure of the connection between the pole piece 700 and the pole lug.

[0055] The specific process of the battery manufacturing method is introduced below, 1. coating the foil with active material; 2. cold pressing the foil and the active material layer; 3. dividing the foil into strips into pole pieces 700; 4. embossing the pole pieces 700 to form grooves 300; 5. winding the pole pieces 700 to form the battery cells 100; 6. placing the battery cells 100 into the shell and injecting the electrolyte; 7. forming; 8. forming, grading and testing to form the battery.

[0056] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. A battery, characterized in that include: A housing having a storage cavity; A battery cell is arranged in the storage cavity, and the battery cell includes a straight portion and a curved portion, wherein two ends of the curved portion are respectively connected to the two straight portions, wherein a groove is arranged on the curved portion, and the groove is used to accommodate electrolyte.

2. The battery according to claim 1, characterized in that The bending portion has a plurality of first slot columns and a second slot column, each of the first slot column and the second slot column includes a plurality of grooves arranged along a first direction, and along a second direction, the first slot column and the second slot column are alternately arranged, and the first direction is perpendicular to the second direction.

3. The battery according to claim 2, characterized in that Along the second direction, the first groove row and the second groove row are staggered.

4. The battery according to claim 3, characterized in that The first groove row and the second groove row are staggered by a distance A, 0.3 mm ≤ A ≤ 9 mm.

5. The battery according to claim 2, characterized in that The distance between the center line of the first groove row and the center line of the second groove row in the second direction is B, and 0.6 mm≤B≤10 mm.

6. The battery according to claim 1, characterized in that The depth of the groove is C, 3um≤C≤15um.

7. The battery according to claim 1, characterized in that There are multiple curved portions, and the arc lengths of each curved portion are different. The arc lengths of the curved portions gradually increase from the straight portion to the curved portion, wherein the grooves of two adjacent curved portions are staggered in the width direction of the battery cell.

8. A battery manufacturing method, characterized in that: The following steps are involved: A pole piece is prepared; Embossing on the pole piece so that a groove is formed on the pole piece; The pole pieces are wound to form a battery core.

9. The battery manufacturing method according to claim 8, characterized in that: The battery cell comprises a straight portion and a curved portion, and two ends of the curved portion are respectively connected to the two straight portions. The battery manufacturing method further comprises a step of flattening the grooves on the straight portions.

10. The battery manufacturing method according to claim 8, characterized in that: The battery manufacturing method further includes the steps of making the pole piece, welding the pole lug to the pole piece, and avoiding the area where the pole piece and the pole lug are connected when embossing the pole piece.

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