Battery cell, battery, battery cell manufacturing method and forming equipment

Abstract

The invention provides a battery cell, a battery, a battery cell manufacturing method and forming equipment, and relates to the technical field of batteries. The battery cell comprises pole pieces and a diaphragm, the diaphragm is clamped between the two pole pieces, and the pole pieces and the diaphragm are wound together; the pole piece comprises a coating area and an empty foil area, and the empty foil area is positioned at the end part of the coating area along the winding axial direction of the pole piece; the empty foil area is provided with a bending line, and the empty foil area is bent relative to the coating area to form a tab; the tab is provided with a plurality of folding parts, the plurality of folding parts are arranged along the winding direction of the pole piece, and the folding parts are folded relative to the end surface of the battery cell. According to the invention, the arrangement mode of the tabs is optimized, so that regularly arranged welding planes are formed at the end parts of the battery cells, the falling of active materials in the kneading process is reduced, the short circuit defect is improved, and the manufacturing difficulty is reduced; and meanwhile, the manufacturing cost of the battery cell with the laser cutting and laminating flattening structure is reduced, the welding difficulty is reduced, and the quality of the battery is ensured to the greatest extent.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery cell, a battery, a battery cell manufacturing method and a molding device. Background Art

[0002] With the development of electronic technology, lithium-ion batteries have been widely used due to their advantages such as high specific power, long cycle life, good safety performance and no pollution.

[0003] In the battery manufacturing process, tab flattening is a key process. Specifically, tab flattening is to use specific equipment and technology to make the tab surface of the battery cell reach a flat and consistent standard, which helps to reduce the performance degradation or safety problems that may be caused by the irregularity of the tab during the charging and discharging process of the battery cell. In the related art, the effect of tab flattening is poor. Summary of the invention

[0004] In view of the above problems, the embodiments of the present application provide a battery cell, a battery, a battery cell manufacturing method and a molding device, which optimize the arrangement of the pole ears, thereby forming a regularly arranged welding surface at the end of the battery cell, which helps to reduce the shedding of active materials during the flattening process, improve short circuit defects, and reduce manufacturing difficulty; at the same time, it helps to reduce the manufacturing cost of laser-cut, stacked and flattened structure batteries, reduce welding difficulty, and ensure the quality of the battery to the greatest extent.

[0005] In order to achieve the above objectives, this application provides the following technical solutions:

[0006] According to a first aspect of an embodiment of the present application, there is provided a battery cell, comprising a pole piece and a diaphragm; the pole piece comprises a coated area and a hollow foil area, the hollow foil area being located at the end of the coated area along the axial direction of the pole piece winding; the diaphragm is sandwiched between two pole pieces, and the pole piece and the diaphragm are wound together; the hollow foil area is bent relative to the coated area to form a pole ear; the pole ear has a plurality of folding portions, the plurality of folding portions are arranged along the winding direction of the pole piece, and the folding portions are all folded relative to the end face of the battery cell.

[0007] In a feasible embodiment, a plurality of the folded portions are folded toward the winding core.

[0008] In a feasible implementation, the spacings between adjacent folding portions are equal; or, the central angles between adjacent folding portions are equal.

[0009] In a feasible embodiment, there are at least two folding parts, and there is a forming angle A between each folding part, and the forming angle A ranges from 5 to 180 degrees.

[0010] In a feasible implementation, there is a forming avoidance zone between two adjacent forming planes forming the folding portion, the included angle of the forming avoidance zone is B, and the included angle range of B is between 0-5°.

[0011] In a feasible implementation, the hollow foil area has a bending line, and the hollow foil area is bent relative to the coated area along the bending line toward the winding center of the battery cell to form the pole ear.

[0012] In a feasible embodiment, the empty foil area includes a first reserved section, a transition section and a pole lug section, the first reserved section, the transition section and the pole lug section are arranged in sequence along the length direction of the pole piece, and the first reserved section is located on the inner side of the battery cell winding; the height of the pole lug section is greater than the height of the first reserved section, and the side of the transition section is inclined relative to the length direction of the pole piece.

[0013] In one feasible embodiment, the side of the first reserved section facing away from the coating area is flush with the bending line; and / or the dimension of the first reserved section along the length direction of the pole piece is greater than or equal to 10 mm and less than or equal to 500 mm.

[0014] In a feasible implementation, the height dimension of the bent portion of the pole lug segment along the bending line is greater than or equal to 2 mm and less than or equal to 8 mm.

[0015] In a feasible implementation, the empty foil area further includes a second reserved section, which is connected to the pole lug section; the second reserved section is located on the outside of the battery cell winding, and the side of the second reserved section facing away from the coating area is flush with the bending line.

[0016] In a feasible embodiment, the bending line extends along the length direction of the pole piece, and the empty foil area forms a buffer zone and a bending zone on both sides of the bending line, respectively, the buffer zone is connected to the coating zone, and the bending zone is located on the side of the buffer zone away from the coating zone; the empty foil area is configured to bend the bending zone relative to the coating zone along the bending line.

[0017] In a feasible implementation, the buffer area is provided with a plurality of immersion holes distributed at intervals, and the immersion holes are configured to form an immersion channel between two sides of the empty foil area.

[0018] In a feasible implementation, the diameter of the immersion hole is greater than or equal to 0.1 mm and less than or equal to 0.5 mm.

[0019] A second aspect of an embodiment of the present application provides a battery, the battery comprising a battery cell.

[0020] A third aspect of the embodiments of the present application provides a method for manufacturing a battery cell, the method comprising: winding a pole piece, and bending a hollow foil area at an end of the pole piece along a direction from an outer arc surface of the battery cell to a center of the battery cell;

[0021] The empty foil area bent at the end of the battery cell is flattened to form a flat surface.

[0022] In an achievable implementation, the pole piece is a continuous structure, and the step of winding the pole piece further includes:

[0023] During the winding process, the battery cell is bent along the direction from the outer arc surface of the battery cell to the center of the battery cell while being wound, and the empty foil area at the end of the electrode sheet forms a plurality of raised portions and folded portions spaced apart along the winding direction;

[0024] The protrusion is rolled at the end of the pole piece so that the protrusion is folded relative to the bent empty foil area and forms a plane.

[0025] A fourth aspect of an embodiment of the present application provides a molding device, including a folding mechanism and a rolling mechanism, to implement the battery cell manufacturing method of the first embodiment.

[0026] In an achievable implementation, the folding mechanism is used to form a folded portion in the empty foil area at the end of the pole piece;

[0027] Wherein, the folding mechanism bends one by one along the outer arc surface of the battery cell to the center of the battery cell;

[0028] Alternatively, the folding mechanism performs 360° rolling and pressing bending in the outer arc direction of the battery core.

[0029] In a feasible implementation, the two side edges of the folding mechanism are arranged to be parallel; or, an angle C is formed between the two side edges of the folding mechanism, and the angle range of C is between 0-5°.

[0030] In a feasible implementation, the rolling mechanism is used to roll the protrusion at the end of the pole piece so that the protrusion is folded relative to the bent empty foil area and forms a plane.

[0031] The embodiments of the present application provide a cell, a battery, a method for manufacturing a cell, and a molding device, including a pole piece and a diaphragm, wherein the diaphragm is sandwiched between the two pole pieces, so as to prevent the positive and negative pole pieces from directly contacting each other and causing a short circuit, thereby ensuring the safety performance of the battery. The empty foil area is bent toward the center of the winding to form a pole ear, and the pole ear has a folding portion arranged at intervals, and the folding portion is pressed onto the surface of the pole ear to form a welding plane at the end of the cell. In this way, the present application optimizes the arrangement of the pole ears, and forms a regularly arranged welding plane at the end of the cell, thereby helping to reduce the shedding of active materials during the flattening process, avoiding deformation of the pole ears, improving short circuit defects, and reducing manufacturing difficulty; at the same time, it helps to reduce the manufacturing cost of laser-cut, stacked, and flattened structure cells, reduce welding difficulty, and maximize battery quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of the structure of a battery cell provided in an embodiment of the present application;

[0033] Figure 2 A front view of a battery cell provided in an embodiment of the present application;

[0034] Figure 3 A top view of a battery cell provided in an embodiment of the present application;

[0035] Figure 4 A cross-sectional view of a battery cell provided in an embodiment of the present application;

[0036] Figure 5 A schematic diagram of the structure of the raised portion of the pole piece provided in an embodiment of the present application;

[0037] Figure 6 for Figure 5 A partial enlarged schematic diagram of part I;

[0038] Figure 7 A schematic diagram of the structure of the folding portion of the battery cell provided in an embodiment of the present application;

[0039] Figure 8 for Figure 7 A partial enlarged schematic diagram of part II;

[0040] Fig. 9 This is a schematic diagram of the structure after the pole piece provided in the embodiment of the present application is flattened;

[0041] Fig.10 A flow chart of a battery cell manufacturing method provided in an embodiment of the present application.

[0042] Description of reference numerals:

[0043] 100-battery cells;

[0044] 110-pole piece; 111-coating area; 112-empty foil area;

[0045] 1121-first reserved section; 1122-transition section; 1123-ear section;

[0046] 1124-second reserved section; 113-bending line; 114-folding portion;

[0047] 115- buffer zone; 116- bending zone; 1161- immersion hole;

[0048] 117- raised portion;

[0049] 200-folding mechanism; 300-rolling mechanism. DETAILED DESCRIPTION

[0050] Traditional wound batteries are mainly single-ear or multi-ear wound batteries. Full-ear wound batteries are increasingly recognized due to their low internal resistance and high energy density. The manufacturing method of full-ear wound batteries is usually to coat one end of the positive and negative electrodes with active materials (the part coated with active materials is called the coating area), and the other end is a blank part (that is, no active material is coated, the part is called the empty foil area). During the winding process of the positive and negative electrodes (or after the winding of the positive and negative electrodes is completed), the blank part is flattened to form a full-ear.

[0051] In the related art, during the process of folding the blank part inward, there are two types of full-tab battery cells: one is a laser-cut laminated structure, and the other is a structure that is directly wound without laser die-cutting and then flattened as a whole. However, the laser-cut laminated structure battery cell has a relatively high manufacturing cost and a difficult welding process; the overall flattened structure has a lot of metal shavings, which is easy to cause short circuit risks and is difficult to manufacture.

[0052] In response to the above technical problems, the embodiments of the present application provide a cell, a battery, a method for manufacturing a cell, and a molding device, including a pole piece and a diaphragm. The diaphragm is sandwiched between two pole pieces. This helps prevent the positive and negative pole pieces from directly contacting each other and causing a short circuit, thereby ensuring the safety performance of the battery. The empty foil area is bent toward the center of the winding to form a pole ear. The pole ear has a folding portion that is spaced apart. The folding portion is pressed onto the surface of the pole ear to form a welding surface at the end of the cell. In this way, the present application optimizes the arrangement of the pole ears and forms a regularly arranged welding plane at the end of the cell, thereby helping to reduce the shedding of active materials during the flattening process, avoiding deformation of the pole ears, improving short circuit defects, and reducing manufacturing difficulty; at the same time, it helps to reduce the manufacturing cost of laser-cut, stacked, and flattened structure cells, reduce welding difficulty, and maximize battery quality.

[0053] In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below in conjunction with the drawings in the embodiments of the present application. In the drawings, the same or similar reference numerals throughout represent the same or similar parts or parts with the same or similar functions. The described embodiments are part of the embodiments of the present application, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limitations on the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0054] The embodiment of the present application provides a battery, which may include a housing and a battery cell, wherein the housing has a receiving cavity, and the battery cell is received in the receiving cavity. In the embodiment of the present application, the housing may be an aluminum housing, or the housing may be a steel housing, which is not limited in the present embodiment. The battery may be a lithium-ion battery or a sodium-ion battery, etc., which is not limited in the present embodiment.

[0055] The battery cell includes pole pieces, which include positive pole pieces and negative pole pieces. A separator is sandwiched between the positive pole pieces and the negative pole pieces. The pole pieces and separators are stacked and wound to form a battery cell. The positive pole ear of the positive pole piece and the negative pole ear of the negative pole piece are located at both ends of the battery cell. After winding and flattening the pole ears, the positive pole ear of the positive pole piece and the negative pole ear on the negative pole piece are stacked to form a ring shape.

[0056] It should be noted that the diaphragm is an insulating film, which helps prevent the positive and negative electrodes from directly contacting each other and causing a short circuit, thereby ensuring the safety performance of the battery.

[0057] Reference Figures 1 to 3 As shown, an embodiment of the present application provides a battery cell 100 including a pole piece 110 . The pole piece 110 includes a coating area 111 and a hollow foil area 112 . The hollow foil area 112 is located at the end of the coating area 111 along the winding axis of the pole piece 110 .

[0058] In the embodiment of the present application, the coating area 111 is used to coat the stirred slurry. This step is a key production step in the coating process of the lithium battery pole piece 110. It mainly involves uniformly coating the stirred solution on the pole piece 110. This process not only affects the capacity, internal resistance, cycle life and safety of the battery, but also has an important impact on the coating effect. The slurry contains organic solvents, which are dried during the coating process to form the pole piece 110 of the battery. Therefore, the portion coated with the active material is called the coating area 111.

[0059] In the embodiment of the present application, the empty foil area 112 is a blank part, that is, no active material is coated. This part is called the empty foil area 112. During the winding process of the positive and negative electrode sheets 110 or after the winding of the positive and negative electrode sheets 110 is completed, the above-mentioned blank part is flattened to form a pole ear.

[0060] Reference Figure 4 As shown, the empty foil area 112 has a bending line 113, and the empty foil area 112 is bent along the bending line 113 toward the winding center of the battery cell 100 relative to the coated area 111, and forms a pole ear. It can be understood that the bending line 113 is the position or line where the empty foil area 112 is bent during the bending process. Among them, the bending direction of the bending line 113 is not limited. Exemplarily, when the empty foil area 112 is bent along the bending line 113 toward the winding center of the battery cell 100 relative to the coated area 111, it can be bent clockwise; or, it can be bent counterclockwise. This embodiment is not limited to this.

[0061] Reference Figure 2 and Figure 3 As shown, the pole ear has a plurality of folding portions 114, which are arranged at intervals along the winding direction of the pole piece 110, and the folding portions 114 are all folded relative to the end surface of the battery cell 100. In the embodiment of the present application, the number of the folding portions 114 is not limited, and the number of the folding portions 114 can be set according to actual needs.

[0062] It should be noted that the reason why the tab has multiple folding portions 114 is that: since the tab is a structure that protrudes to the outside of the pole piece 110 and is discontinuous and extremely thin, if it is not folded, the tab is prone to folding during the roller and winding process of the cut pole piece 110, which affects the quality of the produced battery. Therefore, in the embodiment of the present application, the tab has multiple folding portions 114, which is conducive to increasing the thickness of the tab, thereby facilitating the bending of the tab.

[0063] In the embodiment of the present application, the multiple folding portions 114 are all folded relative to the end surface of the battery cell 100. There is no limitation on the folding direction of the multiple folding portions 114. For example, the multiple folding portions 114 can be folded in the same direction; or, the multiple folding portions 114 can be folded in different directions. In this embodiment, the multiple folding portions 114 are folded in the same direction as an example for explanation.

[0064] Therefore, in the battery cell provided in this embodiment, the empty foil area is bent toward the winding center to form a pole ear, and the pole ear has a folded portion arranged at intervals, and the folded portion is pressed to the surface of the pole ear to form a welding plane at the end of the battery cell. In this way, it is helpful to optimize the arrangement of the pole ears and form a regularly arranged welding plane at the end of the battery cell, thereby helping to reduce the shedding of active materials during the flattening process, avoiding deformation of the pole ears, improving short circuit defects, and reducing manufacturing difficulty; at the same time, it is helpful to reduce the manufacturing cost of the laser cut, stacked and flattened structure battery cell, reduce the difficulty of welding, and maximize the quality of the battery.

[0065] Among them, in order to further optimize the arrangement of the tabs, refer to Figures 5 to 8 As shown, in one embodiment, the spacing between adjacent folding portions 114 may be equal; or the spacing between adjacent folding portions 114 may be unequal. In this embodiment, the spacing between adjacent folding portions 114 is not further limited and can be set according to actual needs.

[0066] In this embodiment, the equal spacing between adjacent folding portions 114 is mainly used as an example for explanation. In this way, it is helpful to ensure that the folding portions 114 are arranged regularly, so that during the flattening process, the shedding of active materials can be minimized to the greatest extent, and the deformation of the tabs can be avoided; on the other hand, it is helpful to ensure the stability of the bending position; on the other hand, it is also helpful to realize the process and improve the appearance of the battery cell 100.

[0067] One embodiment is, referring to Figures 5 to 9 As shown, the central angles of adjacent folded portions 114 may be equal; or, the central angles of adjacent folded portions 114 may be unequal. In this embodiment, the central angles of adjacent folded portions 114 are equal as an example for description.

[0068] In this way, it is helpful to ensure that the folding parts 114 are arranged regularly and bent one by one at equal angles in the axial direction, so as to minimize the shedding of active materials during the flattening process and avoid deformation of the pole ear; on the other hand, it is helpful to ensure the stability of the bending position; on the other hand, it is also beneficial to the realization of the process and improve the appearance of the battery cell 100; on the other hand, no great pressure is required when flattening the pole ear, which can reduce the stress of bending the pole ear and ensure the quality of the battery.

[0069] In order to further optimize the arrangement of the tabs, in one practicable implementation, referring to Figures 5 to 9 As shown, the folding directions of the plurality of folding portions 114 relative to the central angle of the battery cell 100 may be the same; or, the folding directions of the plurality of folding portions 114 relative to the central angle of the battery cell 100 may be different.

[0070] In this embodiment, the folding directions of the multiple folding parts 114 relative to the central angle of the battery cell 100 are the same. In this way, it is helpful to ensure that the folding parts 114 are arranged regularly, so that during the flattening process, the shedding of active materials can be minimized to the greatest extent, and the deformation of the tabs can be avoided; on the other hand, it is helpful to ensure the stability of the bending position; on the other hand, it is also helpful to realize the process and improve the appearance of the battery cell 100; on the other hand, when flattening the tabs, no great pressure is required, which can reduce the stress of bending the tabs and ensure the quality of the battery.

[0071] In one possible implementation, referring to Figure 6 As shown, there are at least two folding portions 114, and a forming angle A may be formed between each folding portion 114, and the angle range of the forming angle A may be between 5-180°. Exemplarily, the angle of the forming angle A may be 5°, 100°, 150°, 180°, or any value between 5-180°. This embodiment is not limited to this. In this way, it helps to ensure that the end surface of the battery cell after the folded pole ear is smoother.

[0072] It should be noted that, when the end face of the battery cell is circular, the forming angle A of the folded portion 114 may be a central angle, where the central angle is the angle between two radii; or, when the end face of the battery cell is a regular polygon, the forming angle A of the folded portion 114 may be a central angle, where the central angle is the central angle of the circumscribed circle corresponding to each side of the regular polygon. This embodiment does not limit this.

[0073] In one possible implementation, referring to Figure 6 As shown, there is a forming avoidance zone between two adjacent forming planes forming the folding portion 114, and the angle of the forming avoidance zone is B, and the angle range of B is between 0-5°. Exemplarily, the angle B of the forming avoidance zone can be 0°, 1°, 2°, 3°, 4°, 5° or any value between 0-5°. This embodiment is not limited to this.

[0074] If the angle B of the forming avoidance zone is less than 0°, or the angle B of the forming avoidance zone is greater than 5°, the intermittent triangular convex structure cannot be formed well during the two side push forming. Therefore, the present application stipulates that the angle B of the forming avoidance zone is between 0-5°, which not only helps to ensure that the end face of the battery cell after the folded tab is smoother, but also can naturally form an intermittent triangular convex structure.

[0075] It should be noted that, when the end face of the battery cell is circular, the forming angle A of the forming avoidance zone may be a central angle, where the central angle is the angle between two radii; or, when the end face of the battery cell is a regular polygon, the forming angle A of the forming avoidance zone may be a central angle, where the central angle is the central angle of the circumscribed circle corresponding to each side of the regular polygon. This embodiment does not limit this.

[0076] In one possible implementation, referring to Figure 4 As shown, the empty foil area 112 may include a first reserved section 1121, a transition section 1122 and a pole lug section 1123, which are arranged in sequence along the length direction of the pole piece 110, and the first reserved section 1121 is located on the inner side of the winding of the battery cell 100.

[0077] In the embodiment of the present application, the first reserved section 1121 is a non-electrode ear area. This design takes into account the ductility of the pole piece 110 during the rolling process, which helps to avoid wrinkling and breaking of the pole piece 110 during rolling and winding; in addition, it also helps to easily remove the film after rolling without affecting the performance of the pole piece 110, improves the processing quality of the pole piece 110, and helps to ensure the performance and safety of the battery. In the embodiment of the present application, the pole ear section 1123 is an area that is bent to form a pole ear.

[0078] In the present application, refer to Figure 4 As shown, the height of the pole ear segment 1123 is greater than the height of the first reserved segment 1121. This is because the pole ear is the lead-out part of the positive and negative poles of the battery, which is used for contact during charging and discharging. Its design and position are crucial to the performance and safety of the battery. During the winding process of the battery, increasing the height of the pole ear segment 1123 can ensure that the pole ear has enough space inside the battery to facilitate the smooth flow of current during battery charging and discharging, optimize the distribution of current inside the battery, reduce internal resistance, and thus improve the energy conversion efficiency and service life of the battery; in addition, by increasing the height of the pole ear segment 1123, the distribution of electrolyte inside the battery can be optimized to avoid the degradation of battery performance caused by uneven distribution of electrolyte. At the same time, this design also helps to enhance the flow of electrolyte inside the battery, avoid wrinkles, bulges, etc. on the surface of the battery packaging bag caused by electrolyte overflow, thereby improving the yield rate of the battery.

[0079] It should be noted that there is no limitation on the height difference between the pole ear section 1123 and the first reserved section 1121 , and it can be set according to actual needs.

[0080] In the present application, refer to Figure 4As shown, the side of the transition section 1122 is inclined relative to the length direction of the pole piece 110. It can be understood that the inclination of the transition section 1122 increases along the length direction of the pole piece 110. In this way, it helps to prevent the hollow foil area 112 from blocking the winding pinhole when it is bent and flattened during winding, thereby ensuring the smooth bending of the hollow foil area 112. There is no limitation on the inclination angle of the transition section 1122, which can be set according to actual needs.

[0081] In one possible implementation, referring to Figure 4 As shown, the side of the first reserved section 1121 away from the coating area 111 is flush with the bending line 113. Such a design improves the battery power characteristics from the perspective of the pole ear, the distance the current flows through is short, the current density is evenly distributed at a high rate, and high power density can be achieved. At the same time, the heat generated by the pole piece 110 is also small, which not only optimizes the performance of the battery, but also improves the safety and reliability of the battery.

[0082] In the embodiment of the present application, the dimension of the first reserved section 1121 along the length direction of the pole piece 110 is greater than or equal to 10 mm and less than or equal to 500 mm. Exemplarily, the length of the first reserved section 1121 can be 10 mm, 50 mm, 100 mm, 150 mm, 30 mm, 50 mm, or any value between 10 mm and 500 mm, which is not limited in the present embodiment.

[0083] In this way, on the one hand, it helps to avoid the problem that the pole piece 110 cannot be wrinkled and broken during rolling and winding when the length of the first reserved section 1121 is too small; on the other hand, it helps to avoid the problem that the length of the pole lug section 1123 is affected when the length of the first reserved section 1121 is too large, thereby helping to ensure that there is enough space for the pole lug inside the battery, ensuring the smooth flow of current when the battery is charged and discharged, optimizing the distribution of current inside the battery, reducing internal resistance, and thus improving the energy conversion efficiency and service life of the battery.

[0084] In an achievable implementation, the height dimension of the bent portion of the pole lug segment 1123 along the bending line 113 is greater than or equal to 2 mm and less than or equal to 8 mm. Exemplarily, the height of the pole lug segment 1123 can be 2 mm, 3 mm, 4 mm, 6 mm, 8 mm, or any value between 2 mm and 8 mm. This embodiment does not limit this.

[0085] This helps to ensure that the height of the pole lug segment 1123 is within a reasonable range, so that during the winding process of the battery, there is enough space for the pole lug inside the battery to facilitate the smooth flow of current during battery charging and discharging, optimize the distribution of current inside the battery, reduce internal resistance, and thus improve the energy conversion efficiency and service life of the battery; in addition, the distribution of electrolyte inside the battery can be optimized to avoid degradation of battery performance due to uneven distribution of electrolyte.

[0086] In one possible implementation, referring to Figure 4 As shown, the empty foil area 112 may further include a second reserved section 1124 , which is connected to the pole lug section 1123 ; the second reserved section 1124 is located on the outer side of the winding of the battery cell 100 , and the side of the second reserved section 1124 facing away from the coating area 111 is flush with the bending line 113 .

[0087] In the embodiment of the present application, the second reserved section 1124 is a pole-ear-free area. This design helps to shorten the distance that the current flows, thereby achieving uniformity of current density distribution at a large rate, and thus achieving high power density; in addition, this design can also reduce the heat generated by the pole piece 110 and improve the performance and safety of the battery.

[0088] In the embodiment of the present application, the side of the second reserved section 1124 away from the coating area 111 is flush with the bending line 113. Such a design improves the battery power characteristics from the perspective of the pole ear, the distance the current flows through is short, the current density is evenly distributed at a high rate, and high power density can be achieved. At the same time, the heat generated by the pole piece 110 is also small, which not only optimizes the performance of the battery, but also improves the safety and reliability of the battery.

[0089] In one possible implementation, referring to Figure 4 As shown, the bending line 113 extends along the length direction of the pole piece 110, and the empty foil area 112 forms a buffer area 115 and a bending area 116 on both sides of the bending line 113, respectively. The buffer area 115 is connected to the coating area 111, and the bending area 116 is located on the side of the buffer area 115 away from the coating area 111; the empty foil area 112 is configured to bend the bending area 116 relative to the coating area 111 along the bending line 113.

[0090] In the embodiment of the present application, by including the buffer zone 115, on the one hand, it helps to increase the buffer zone 115 area of ​​the empty foil area 112 at the pole tab position, thereby helping to increase the stress buffer zone 115 of the empty foil area 112 of the pole tab, thereby protecting the pole tab from breakage due to external reasons to the greatest extent; on the other hand, it can prevent the pole piece 110 from breakage caused by the stress generated during the thickness change of the pole piece 110 when the battery expands during charging and discharging, thereby protecting the safety performance of the battery to the greatest extent.

[0091] It should be noted that the size and shape of the buffer zone 115 and the bending zone 116 are not further limited and can be set according to actual needs.

[0092] In one possible implementation, referring to Figure 4 As shown, the buffer area 115 is provided with a plurality of immersion holes 1161 distributed at intervals, and the immersion holes 1161 are configured to form an immersion channel between the two sides of the empty foil area 112 .

[0093] It should be noted that the present application may not process the immersion hole 1161, which helps to retain the complete empty foil area 112, and the electrolyte can enter from the gap of the bent ear during injection, and this embodiment does not limit this.

[0094] In the embodiment of the present application, there is no limitation on the processing method of the immersion hole 1161. For example, the immersion hole 1161 can be processed by laser die cutting, which is not limited in the present embodiment. In addition, there is no limitation on the shape, number, and size of the immersion hole 1161, which can be set according to actual needs.

[0095] In the embodiment of the present application, the immersion hole 1161 is opened in the buffer zone 115 , so that it will not interfere with the normal bending of the bending zone 116 and help ensure the structural integrity of the bending zone 116 .

[0096] In this way, by processing the immersion hole 1161, on the one hand, it helps to increase the contact area between the electrode 110 and the electrolyte, making the electrochemical reaction more complete, thereby improving the capacity and energy density of the battery; on the other hand, the immersion hole 1161 can form an ion channel, shortening the migration distance of ions in the electrode 110, thereby improving the charge and discharge rate of the battery; on the other hand, during the charge and discharge process, since the active material will undergo volume changes, processing the immersion hole 1161 can alleviate this volume effect and prevent damage to the structure of the electrode 110, thereby maximizing the cycle stability of the battery; on the other hand, processing the immersion hole 1161 can increase the heat dissipation area of ​​the electrode 110, which is beneficial to the dissipation of heat generated by the battery during operation, thereby improving the thermal stability of the battery.

[0097] In an achievable implementation, the diameter of the immersion hole 1161 is greater than or equal to 0.1 mm and less than or equal to 0.5 mm. For example, the diameter of the immersion hole 1161 can be set to 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, or any value between 0.1 mm and 0.5 mm according to actual needs. This embodiment is not limited to this.

[0098] This helps ensure that the diameter of the immersion hole 1161 is within an appropriate range. On the one hand, it helps avoid the problem that the contact area between the electrode 110 and the electrolyte is too small and the electrochemical reaction is insufficient when the diameter of the immersion hole 1161 is too small. On the other hand, it also helps avoid the problem that the electrolyte may be lost and the battery performance may be affected when the diameter of the immersion hole 1161 is too large.

[0099] Reference Fig.10 As shown, an embodiment of the present application provides a method for manufacturing a battery cell, which is used to prepare a battery cell. The method includes:

[0100] S100: Winding the pole piece, and bending the empty foil area at the end of the pole piece along the direction from the outer arc surface of the battery cell to the center of the battery cell.

[0101] In the process of winding the pole piece, the winding can be performed in the axial direction of the winding needle. For example, the winding needle can be understood as a winding shaft, which is conducive to winding and plays a supporting and fixing role during the winding process to maintain stability during the winding process.

[0102] S200: Flatten the bent empty foil area at the end of the battery cell to form a flat surface.

[0103] In the flattening process, a flattening structure may be used for flattening. For example, the flattening structure may be a flattening cylinder, which is not limited in this embodiment.

[0104] In this way, after the winding is completed, the empty foil area 112 and the folded portion 114 are flattened by the flattening structure to achieve a flat welding plane of the collector plate. Fig. 9 shown.

[0105] It should be noted that the plane formed in this embodiment can be understood as a relatively flat plane.

[0106] In an achievable implementation, the pole piece is a continuous structure, and the step of winding the pole piece may further include:

[0107] During the winding process, the battery cell is bent along the direction from the outer arc surface to the center of the battery cell while being wound, and the empty foil area at the end of the electrode sheet forms a plurality of raised portions and folded portions spaced apart along the winding direction;

[0108] The protrusion is rolled at the end of the pole piece so that the protrusion is folded relative to the bent hollow foil area and forms a plane.

[0109] In this embodiment, the shape of the protrusion 117 is not limited. For example, the shape of the protrusion 117 may be a triangular protrusion; or the shape of the protrusion 117 may be a polygonal protrusion; or the shape of the protrusion 117 may be other shapes. In this embodiment, the shape of the protrusion 117 is a triangular protrusion as an example for description.

[0110] A molding device is also provided in an embodiment of the present application, which may include a folding mechanism and a rolling mechanism to implement the battery cell manufacturing method of embodiment three.

[0111] The folding mechanism 200 is used to form a folded portion 114 in the empty foil area 112 at the end of the electrode. In the process of bending along the outer arc surface of the battery cell 100 to the center of the battery cell 100, the bending can be performed in the following manner:

[0112] One bending method is: refer to Figure 5 and Figure 6 As shown, the folding mechanism 200 bends one by one along the outer arc surface of the battery cell to the center of the battery cell. Specifically, it runs from the outside of the battery cell 100 to the axis direction, and the foil parallel to the axis of the battery cell 100 can be bent one by one at equal intervals or equal angles of 60-90° toward the axis. There is no limitation on the bending angle. Exemplarily, it can be bent one by one at equal intervals or equal angles of 60°; or, it can be bent one by one at equal intervals or equal angles of 70°; or, it can be bent one by one at equal intervals or equal angles of 90°. This embodiment does not limit this, and it can be set according to actual needs. Exemplarily, the folding direction of this embodiment can refer to Figure 6 As shown in the direction of arrow a.

[0113] Another bending method is: refer to Figure 5 and Figure 6 As shown, the folding mechanism 200 performs 360° rolling and pressing bending in the outer arc direction of the battery cell. Specifically, the 360° rolling and pressing bending is performed in the outer arc direction of the battery cell 100, and finally the foil is bent and pressed into an intermittent triangular protrusion on the end face of the battery cell 100. For example, the folding direction of this embodiment can refer to Figure 6 As shown in the direction of arrow b.

[0114] It should be noted that the bending method of the empty foil area 112 in the embodiment of the present application includes but is not limited to the above-mentioned method, and can be specifically set according to actual needs.

[0115] So, refer to Figure 7 and Figure 8As shown, the intermittent triangular protrusion is flattened horizontally on one side by rolling to realize the folding portion 114 of the intermittent foil pole ear, and the pole piece 110 is formed one by one by winding layer by layer, and finally the folding portion 114 is formed on the end face of the battery cell 100, and the outer layer pole ear foil area wraps the inner layer pole ear layer by layer folding structure of the battery cell.

[0116] It should be noted that before step S100, when the battery cell 100 is being manufactured, the edge foil material of the active dressing of the inner circle of the pole piece 110 is reserved with a certain length of non-polar ear area (the first reserved section in this application), and then a foil area with increasing slope (the transition section in this application) is designed to prevent the foil area from bending and flattening to block the winding pinhole during winding. The edge of the pole piece 110 in the middle of the battery cell 100 retains a complete foil area (the pole ear section in this application), and 0-5 circles of the pole piece 110 are reserved at the tail of the pole piece 110 for the extended non-polar ear area (the second reserved section in this application).

[0117] It should be noted that after step S300, a buffer zone 115 of empty foil is reserved between the bent pole ear and the coating area 111. The present application designs a laser die-cut immersion hole 1161 for liquid injection, which is arranged in the longitudinal direction of the pole piece 110, and forms an infiltration channel in the radial direction of the battery cell 100 after winding.

[0118] In which, in the step of rolling the folded portion at the end of the pole piece by the folding mechanism 200: the two side edges of the folding mechanism 200 can be set to be parallel; or, there can be an angle C between the two side edges of the folding mechanism 200, and the angle range of C can be between 0-5°.

[0119] For example, refer to Figure 6 As shown, the angle C between the two sides of the folding mechanism 200 can be 0°, 1°, 2°, 3°, 4°, 5° or any value between 0-5°. In this way, it helps to improve the flatness of the end surface of the battery cell after the tab is folded, and maximize the quality of the battery.

[0120] In the embodiment of the present application, after the folding mechanism 200 completes the bending, a rolling mechanism 300 may be further included, and the rolling mechanism 300 is used to roll the protrusion 117 at the end of the pole piece so that the protrusion 117 is folded relative to the already bent empty foil area 112 and forms a plane. Figure 8 Roll in the direction of the arrow.

[0121] It should be noted that, due to the existence of residual material during the rolling process, the folded and formed plane in this embodiment is not an absolutely flat plane.

[0122] Therefore, the embodiments of the present application provide a cell, a battery, a method for manufacturing a cell, and a molding device, including a pole piece and a diaphragm, wherein the diaphragm is sandwiched between two pole pieces, so as to help prevent the positive and negative pole pieces from directly contacting each other and causing a short circuit, thereby ensuring the safety performance of the battery. The empty foil area is bent toward the center of the winding to form a pole ear, and the pole ear has a folding portion arranged at intervals, and the folding portion is pressed onto the surface of the pole ear to form a welding surface at the end of the cell. In this way, the present application optimizes the arrangement of the pole ears, and forms a regularly arranged welding plane at the end of the cell, thereby helping to reduce the shedding of active materials during the flattening process, avoiding deformation of the pole ears, improving short circuit defects, and reducing manufacturing difficulty; at the same time, it helps to reduce the manufacturing cost of laser-cut, stacked, and flattened structure cells, reduce welding difficulty, and maximize battery quality.

[0123] It should be noted that, in the description of the embodiments of the present application, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, or it can be an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0124] In the description of the embodiments of the present application, the term "and / or" merely indicates an association relationship that describes associated objects, indicating that three relationships may exist. For example, A and / or B may indicate the following three situations: A exists alone, A and B exist at the same time, and B exists alone. In addition, the term "at least one" indicates any combination of at least two of any one or more of a plurality of. For example, at least one of A, B, and C may indicate any one or more elements selected from a set that includes A, B, and C.

[0125] In the description of the embodiments of the present application, the terms "upper", "lower", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on the present application. In addition, the term "plurality" means two or more, unless otherwise precisely and specifically specified.

[0126] In the description of the embodiment of the present application, the terms "first", "second", "third", "fourth", etc. (if present) are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0127] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery cell, characterized in that: The battery cell comprises: A pole piece (110), the pole piece (110) comprising a coating area (111) and a hollow foil area (112), the hollow foil area (112) being located at an end of the coating area (111) along the winding axis of the pole piece (110); A diaphragm, the diaphragm being sandwiched between the two pole pieces (110), the pole pieces (110) and the diaphragm being wound together; The empty foil area (112) is bent relative to the coated area (111) to form a pole ear, the pole ear having a plurality of folding portions (114), the plurality of folding portions (114) being arranged along the winding direction of the pole piece (110), and the folding portions (114) are all folded relative to the end face of the battery cell.

2. The battery cell according to claim 1, characterized in that: The plurality of folded portions (114) are folded toward the winding core.

3. The battery cell according to claim 2, characterized in that: The spacings between adjacent folding portions (114) are equal; or, the central angles between adjacent folding portions (114) are equal.

4. The battery cell according to any one of claims 1 to 3, characterized in that: There are at least two folding parts (114), and a forming angle A is formed between each of the folding parts (114), and the forming angle A ranges from 5 to 180 degrees.

5. The battery cell according to any one of claims 1 to 3, characterized in that: A forming avoidance zone is provided between two adjacent forming planes forming the folding portion (114), the included angle of the forming avoidance zone is B, and the included angle range of B is between 0 and 5 degrees.

6. The battery cell according to any one of claims 1 to 3, characterized in that: The empty foil area (112) has a bending line (113), and the empty foil area (112) is bent relative to the coated area (111) along the bending line (113) toward the winding center of the battery core to form the pole ear.

7. The battery cell according to claim 6, characterized in that: The empty foil area (112) comprises a first reserved section (1121), a transition section (1122) and a pole lug section (1123); the first reserved section (1121), the transition section (1122) and the pole lug section (1123) are arranged in sequence along the length direction of the pole piece (110); the first reserved section (1121) is located on the inner side of the winding of the battery cell; the height of the pole lug section (1123) is greater than the height of the first reserved section (1121); and the side of the transition section (1122) is arranged obliquely relative to the length direction of the pole piece (110).

8. The battery cell according to claim 7, characterized in that: The side of the first reserved section (1121) facing away from the coating area (111) is flush with the bending line (113); and / or the dimension of the first reserved section (1121) along the length direction of the pole piece (110) is greater than or equal to 10 mm and less than or equal to 500 mm.

9. The battery cell according to claim 7, characterized in that: The height dimension of the bent portion of the pole lug segment (1123) along the bending line (113) is greater than or equal to 2 mm and less than or equal to 8 mm.

10. The battery cell according to claim 7, characterized in that: The empty foil area (112) further comprises a second reserved section (1124), wherein the second reserved section (1124) is connected to the pole lug section (1123); the second reserved section (1124) is located on the outer side of the battery cell winding, and the side edge of the second reserved section (1124) facing away from the coating area (111) is flush with the bending line (113).

11. The battery cell according to claim 6, characterized in that: The bending line (113) extends along the length direction of the pole piece (110); the empty foil area (112) forms a buffer area (115) and a bending area (116) on both sides of the bending line (113), respectively; the buffer area (115) is connected to the coating area (111); the bending area (116) is located on a side of the buffer area (115) away from the coating area (111); and the empty foil area (112) is configured to bend the bending area (116) relative to the coating area (111) along the bending line (113).

12. The battery cell according to claim 11, characterized in that: The buffer area (115) is provided with a plurality of immersion holes (1161) distributed at intervals, and the immersion holes (1161) are configured to form an immersion channel between two sides of the empty foil area (112).

13. The battery cell according to claim 12, characterized in that: The diameter of the immersion hole (1161) is greater than or equal to 0.1 mm and less than or equal to 0.5 mm.

14. A battery, characterized in that: The battery comprises the battery cell according to any one of claims 1 to 13.

15. A method for manufacturing a battery cell, characterized in that: Used to prepare the battery cell according to any one of claims 1 to 13; the method comprises: Winding the pole piece, and bending the empty foil area at the end of the pole piece along the direction from the outer arc surface of the battery cell to the center of the battery cell; The empty foil area bent at the end of the battery cell is flattened to form a flat surface.

16. The method for manufacturing a battery cell according to claim 15, characterized in that: The pole piece is a continuous structure, and the step of winding the pole piece further includes: During the winding process, the battery cell is bent along the direction from the outer arc surface of the battery cell to the center of the battery cell while being wound, and the empty foil area at the end of the electrode sheet forms a plurality of raised portions and folded portions spaced apart along the winding direction; The protrusion is rolled at the end of the pole piece so that the protrusion is folded relative to the bent empty foil area and forms a plane.

17. A molding device, characterized in that: It comprises a folding mechanism and a rolling mechanism to realize the battery cell manufacturing method described in claim 15 above.

18. The molding device according to claim 17, characterized in that: The folding mechanism is used to form a folded portion in the empty foil area at the end of the pole piece; Wherein, the folding mechanism bends one by one along the outer arc surface of the battery cell to the center of the battery cell; Alternatively, the folding mechanism performs 360° rolling and pressing bending in the outer arc direction of the battery core.

19. The molding device according to claim 18, characterized in that The two side edges of the folding mechanism are arranged to be parallel; or, there is an angle C between the two side edges of the folding mechanism, and the angle range of C is between 0-5°.

20. The molding device according to claim 18, characterized in that The rolling mechanism is used for rolling the protrusion at the end of the pole piece so that the protrusion is folded relative to the bent empty foil area and forms a plane.

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