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

Abstract

The present disclosure relates to the technical field of batteries, and provides a battery cell, a battery, a battery cell manufacturing method, and a forming device. The battery cell comprises electrode sheets and a separator, wherein the separator is sandwiched between two electrode sheets, and the electrode sheets and the separator are jointly wound. Each electrode sheet comprises a coated region and an uncoated region, and the uncoated region is located at an end portion in the coated region along a winding axial direction of the electrode sheet; the uncoated region has a bending line, and the uncoated region is bent relative to the coated region to form a tab; and the tab comprises multiple folding portions, the multiple folding portions are arranged along a winding direction of the electrode sheet, and the folding portions are all folded relative to an end surface of the battery cell. The present disclosure optimizes the arrangement mode of tabs, so as to form a regularly arranged welding plane at an end portion of a battery cell, thereby helping to reduce the shedding of an active material during flattening, mitigate short-circuit failure, and reduce the manufacturing difficulty. In addition, the present disclosure is conducive to reducing the manufacturing costs of battery cells having a laser-notched, stacked, and flattened structure, reducing the welding difficulty, and ensuring the quality of batteries to the maximum extent.

Description

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

[0001] Cross-reference to related applications

[0002] The present disclosure claims priority to the Chinese patent application No. 202411395533.4, filed on September 30, 2024, entitled "Battery cell, battery, battery cell manufacturing method and forming device", the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0003] The present disclosure relates to the technical field of battery, and in particular to a battery cell, a battery, a battery cell manufacturing method and a forming device. BACKGROUND

[0004] With the development of electronic technology, lithium ion batteries have high specific power, long cycle life, good safety performance, and no pollution, and are widely used.

[0005] In the battery manufacturing process, the tab flattening is a key process. Specifically, the tab flattening is to make the surface of the tab of the battery cell flat and consistent through specific equipment and technology, which helps to reduce the performance degradation or safety problems that may be caused by irregular tabs during charging and discharging. In the related art, the effect of tab flattening is poor. SUMMARY

[0006] In view of the above problems, the present disclosure provides a battery cell, a battery, a battery cell manufacturing method and a forming device, which optimizes the arrangement mode of the tab, thereby forming a regularly arranged welding surface at the end of the battery cell, which helps to reduce the shedding of active material during the flattening process, improve short circuit defects, and reduce manufacturing difficulty; at the same time, it helps to reduce the manufacturing cost of the laser cutting and stacking flat structure battery cell, reduce the welding difficulty, and maximize the quality of the battery.

[0007] To achieve the above purpose, the present disclosure provides the following technical solutions:

[0008] The first aspect of the present disclosure provides a battery cell, which comprises a tab and a separator; the tab comprises a coated area and a hollow foil area, the hollow foil area is located at the end of the coated area along the winding axis of the tab; the separator is clamped between two tabs, and the tab and the separator are co-wound; the hollow foil area is bent relative to the coated area and forms a tab; the tab has a plurality of folding parts, and the plurality of folding parts are arranged along the winding direction of the tab, and the folding parts are all folded relative to the end surface of the battery cell.

[0009] In an implementable embodiment, the plurality of folding parts are folded towards the direction of the core.

[0010] In an implementable embodiment, the spacing between adjacent folding portions is equal; or, the central angles between adjacent folding portions are equal.

[0011] In an implementable embodiment, there are at least two folding portions, each folding portion has a shaped included angle A, and the range of the shaped included angle A is 5-180°.

[0012] In an implementable embodiment, there is a shaped avoidance zone in the two adjacent shaped planes forming the folding portion, the shaped avoidance zone has an included angle B, and the range of the included angle B is 0-5°.

[0013] In an implementable embodiment, the empty foil area has a bending line, the empty foil area is bent along the bending line towards the winding center of the battery cell relative to the coated area, and forms the tab.

[0014] In an implementable embodiment, the empty foil area includes a first reserved section, a transition section, and a tab section, the first reserved section, the transition section, and the tab section are sequentially arranged along the length direction of the tab, and the first reserved section is located on the inside of the winding of the battery cell; the height of the tab section is greater than the height of the first reserved section, and the side of the transition section is obliquely arranged relative to the length direction of the tab.

[0015] In an implementable embodiment, the side of the first reserved section away from the coated area is flush with the bending line; and / or, the size of the first reserved section along the length direction of the tab is greater than or equal to 10 mm and less than or equal to 500 mm.

[0016] In an implementable embodiment, the height dimension of the tab section bent along the bending line is greater than or equal to 2 mm and less than or equal to 8 mm.

[0017] In an implementable embodiment, the empty foil area further includes a second reserved section, the second reserved section is connected with the tab section; the second reserved section is located on the outside of the winding of the battery cell, and the side of the second reserved section away from the coated area is flush with the bending line.

[0018] In an implementable embodiment, the bending line extends along the length direction of the tab, the empty foil area forms a buffer area and a bending area on both sides of the bending line, the buffer area is connected with the coated area, and the bending area is located on the side of the buffer area away from the coated area; the empty foil area is configured to bend the bending area relative to the coated area along the bending line.

[0019] In an implementable embodiment, the buffer zone is provided with a plurality of spaced immersion holes configured to form a wicking channel between two sides of the empty foil zone.

[0020] In an implementable embodiment, the diameter of the immersion hole is greater than or equal to 0.1 mm and less than or equal to 0.5 mm.

[0021] The second aspect of the embodiments of the present disclosure provides a battery, which comprises a battery cell.

[0022] The third aspect of the embodiments of the present disclosure provides a battery cell manufacturing method for manufacturing a battery cell, which comprises: winding an electrode sheet, and bending an empty foil zone at the end of the electrode sheet in a direction from the outer arc surface of the battery cell to the center of the battery cell;

[0023] Flattening the empty foil zone at the end of the battery cell to form a flat surface.

[0024] In an implementable embodiment, the electrode sheet is of a continuous structure, and the step of winding the electrode sheet further comprises:

[0025] In the winding process, the empty foil zone at the end of the electrode sheet is bent in the direction from the outer arc surface of the battery cell to the center of the battery cell while being wound, to form a plurality of protrusions and folds spaced in the winding direction;

[0026] Rolling the protrusions at the end of the electrode sheet to fold the protrusions relative to the already bent empty foil zone and form a flat surface.

[0027] The fourth aspect of the embodiments of the present disclosure provides a forming device comprising a folding mechanism and a rolling mechanism to implement the battery cell manufacturing method of the first aspect.

[0028] In an implementable embodiment, the folding mechanism is used to form a fold at the empty foil zone at the end of the electrode sheet;

[0029] The folding mechanism is bent one by one in the direction from the outer arc surface of the battery cell to the center of the battery cell.

[0030] Or, the folding mechanism is 360° rolling type bending in the direction of the outer arc surface of the battery cell.

[0031] In an implementable embodiment, the two sides of the folding mechanism are parallel; or, the folding mechanism has an included angle C between the two sides, and the included angle C ranges from 0 to 5°.

[0032] In an implementable embodiment, the rolling mechanism is used to roll the protrusions at the end of the electrode sheet to fold the protrusions relative to the already bent empty foil zone and form a flat surface.

[0033] The embodiment of the present disclosure provides an electric core, a battery, a manufacturing method of the electric core and a forming device, which comprises a pole piece and a diaphragm, and the diaphragm is clamped between two pole pieces, so as to prevent the direct contact between the positive and negative pole pieces and cause short circuit, and ensure the safety performance of the battery. The hollow foil area is bent to form a tab at the winding center, the tab has a spaced folding part, the folding part is pressed and overlapped to the surface of the tab, and a welding plane is formed at the end of the electric core. In this way, the arrangement mode of the tab is optimized, the regular arrangement of the welding plane is formed at the end of the electric core, so as to help reduce the shedding of the active material in the rubbing process, avoid the deformation of the tab, improve the short circuit defect, reduce the manufacturing difficulty, and at the same time, help reduce the manufacturing cost of the laser cutting and overlapping structure electric core, reduce the welding difficulty, and maximize the quality of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0034] Fig. 1 is a structural schematic diagram of an electric core provided by the embodiment of the present disclosure;

[0035] Fig. 2 is a front view of the electric core provided by the embodiment of the present disclosure;

[0036] Fig. 3 is a top view of the electric core provided by the embodiment of the present disclosure;

[0037] Fig. 4 is a sectional view of the electric core provided by the embodiment of the present disclosure;

[0038] Fig. 5 is a structural schematic diagram of a protruding part of a pole piece provided by the embodiment of the present disclosure;

[0039] Fig. 6 is a local enlarged schematic diagram of part I in Fig. 5;

[0040] Fig. 7 is a structural schematic diagram of a folding part of the electric core provided by the embodiment of the present disclosure;

[0041] Fig. 8 is a local enlarged schematic diagram of part II in Fig. 7;

[0042] Fig. 9 is a structural schematic diagram of the pole piece after rubbing and flattening provided by the embodiment of the present disclosure;

[0043] Fig. 10 is a flow chart of the manufacturing method of the electric core provided by the embodiment of the present disclosure.

[0044] Explanation of reference signs: 100 - cell; 110 - tab; 111 - coated area; 112 - blank foil area; 1121 - first reserved section; 1122 - transition section; 1123 - tab section; 1124 - second reserved section; 113 - bending line; 114 - folding part; 115 - buffer area; 116 - bending area; 1161 - immersion hole; 117 - protruding part; 200 - folding mechanism; 300 - rolling mechanism. DETAILED DESCRIPTION

[0045] Traditional winding type batteries are mainly single-tab or multi-tab winding type batteries. Full-tab winding type batteries are increasingly recognized due to their low internal resistance and high energy density. The manufacturing method of full-tab winding type batteries is usually to coat one end of the positive and negative tabs with active material (the part coated with active material is referred to as a coated area), and the other end is a blank part (i.e., not coated with active material, which is referred to as a blank foil area). During the winding process of the positive and negative tabs (or after the winding of the positive and negative tabs is completed), the blank part is flattened to form a full tab.

[0046] In related technologies, during the inward folding of the blank part, full-tab cells include two types: one is a laser cutting and laminating tab structure, and the other is a whole rubbing flat structure after direct winding without laser cutting. However, the laser cutting and laminating flat structure cell has relatively high manufacturing cost and difficult welding process; the whole rubbing flat structure has more metal scraps, which can easily cause short circuit risk and has high manufacturing difficulty.

[0047] To solve the above technical problems, the embodiments of the present disclosure provide a cell, a battery, a manufacturing method of a cell, and a forming device, which include tabs and a separator. The separator is clamped between two tabs, which helps to prevent short circuit caused by direct contact between the positive and negative tabs and ensures the safety performance of the battery. The blank foil area is bent towards the winding center to form a tab, and the tab has a folding part arranged at intervals. The folding part is pressed and laminated to the surface of the tab to form a welding surface at the end of the cell. In this way, the arrangement of the tab is optimized, a regular arranged welding plane is formed at the end of the cell, which helps to reduce the shedding of active material during the rubbing process, avoid deformation of the tab, improve short circuit defects, and reduce manufacturing difficulty. At the same time, it helps to reduce the manufacturing cost of the laser cutting and laminating flat structure cell, reduce the welding difficulty, and maximize the quality of the battery.

[0048] In order to make the purposes, technical solutions and advantages of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be described in more detail below with reference to the drawings in the embodiments of the present disclosure. In the drawings, identical or similar labels represent identical or similar components or components with identical or similar functions throughout. The described embodiments are part of the embodiments of the present disclosure, rather than all the embodiments. The embodiments described below by reference to the drawings are exemplary and are intended to explain the present disclosure, and cannot be understood as a limitation of the present disclosure. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present disclosure.

[0049] The embodiments of the present disclosure provide a battery, which can include a shell and a cell, the shell has a receiving cavity, and the cell is accommodated in the receiving cavity. In the embodiments of the present disclosure, the shell can be an aluminum shell, or the shell can be a steel shell, and the present embodiment does not limit this. The battery can be a lithium ion battery or a sodium ion battery, and the present embodiment does not limit this.

[0050] The cell includes a pole piece, the pole piece includes a positive pole piece and a negative pole piece, a diaphragm is clamped between the positive pole piece and the negative pole piece, and the pole piece and the diaphragm are stacked to form the cell by winding. The positive pole lug of the positive pole piece and the negative pole lug of the negative pole piece are respectively located at two ends of the cell. After the winding and the rubbing of the pole lug are completed, the positive pole lug of the positive pole piece and the negative pole lug on the negative pole piece are respectively stacked to form a circular ring.

[0051] It should be noted that the diaphragm is an insulating film, thereby helping to prevent short circuit caused by direct contact of the positive pole piece and the negative pole piece, and ensuring the safety performance of the battery.

[0052] Referring to FIGS. 1-3, the embodiments of the present disclosure provide a cell 100, which includes a pole piece 110, the pole piece 110 includes a coated area 111 and a hollow foil area 112, and the hollow foil area 112 is located at the end of the coated area 111 along the winding axis of the pole piece 110.

[0053] In the embodiments of the present disclosure, the coated area 111 is used to coat the uniformly stirred slurry, and this step is a key production step in the coating process of the lithium battery pole piece 110, mainly involving uniformly coating the uniformly 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 influence 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 part coated with the active material is referred to as the coated area 111.

[0054] In the embodiments of the present disclosure, the empty foil area 112 is a blank part, that is, a part not coated with active material, which is referred to as an 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 rubbed flat to form a tab.

[0055] Referring to FIG. 4, the empty foil area 112 has a bending line 113. The empty foil area 112 is bent along the bending line 113 relative to the coated area 111 to the winding center of the battery cell 100 and forms a tab. 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. The bending direction of the bending line 113 is not limited. For example, the empty foil area 112 can be bent clockwise along the bending line 113 relative to the coated area 111 to the winding center of the battery cell 100. Alternatively, the empty foil area 112 can be bent counterclockwise along the bending line 113 relative to the coated area 111 to the winding center of the battery cell 100. The present embodiment does not limit this.

[0056] Referring to FIGS. 2 and 3, the tab has a plurality of folding parts 114. The plurality of folding parts 114 are arranged at intervals along the winding direction of the electrode sheet 110, and the folding parts 114 are each arranged to be folded relative to the end surface of the battery cell 100. In the embodiments of the present disclosure, the number of the folding parts 114 is not limited, and the number of the folding parts 114 can be set according to actual needs.

[0057] It should be noted that the tab has a plurality of folding parts 114 because the tab is a structure that protrudes to the outside of the electrode sheet 110 and is discontinuous and extremely thin. If not folded, the tab is prone to folding during the rolling and winding process of the cut electrode sheet 110, which affects the quality of the produced battery. Therefore, in the embodiments of the present disclosure, the tab has a plurality of folding parts 114, which is beneficial to increase the thickness of the tab and thus facilitate the bending of the tab.

[0058] In the embodiments of the present disclosure, the plurality of folding parts 114 are each arranged to be folded relative to the end surface of the battery cell 100. The folding direction of the plurality of folding parts 114 is not limited. For example, the plurality of folding parts 114 can be folded in the same direction. Alternatively, the plurality of folding parts 114 can be folded in different directions. In the present embodiment, the plurality of folding parts 114 are mainly taken as an example to be folded in the same direction.

[0059] Therefore, the battery cell provided in the present embodiment has the advantages that the empty foil area is bent to the winding center to form a tab, the tab has a plurality of folding parts arranged at intervals, the folding parts are pressed and overlapped to the surface of the tab, and a welding flat surface is formed at the end of the battery cell. In this way, it is helpful to optimize the arrangement mode of the tab, form a regular arrangement of welding flat surfaces at the end of the battery cell, thereby reducing the falling of active material during the rubbing process, avoiding the deformation of the tab, improving the short circuit defect, reducing the manufacturing difficulty, and reducing the manufacturing cost of the laser cutting and overlapping flat structure battery cell, reducing the welding difficulty, and maximizing the quality of the battery.

[0060] In order to further optimize the arrangement of the tabs, referring to FIGS. 5 to 8, in an embodiment, the intervals between the adjacent folding portions 114 can be equal; or the intervals between the adjacent folding portions 114 can be unequal. In the embodiment, the interval values between the adjacent folding portions 114 are not further limited, and can be set according to actual needs.

[0061] In the embodiment, the equal intervals between the adjacent folding portions 114 are mainly taken as an example for description. In this way, it is beneficial to ensure the regular arrangement of the folding portions 114, so that the shedding of the active material during the flattening process can be maximally reduced, and the deformation of the tabs can be avoided; on the other hand, it is beneficial to ensure the stability of the bending position; on the other hand, it is also beneficial to the implementation of the process, and improves the appearance of the battery cell 100.

[0062] In an embodiment, referring to FIGS. 5 to 9, the central angles between the adjacent folding portions 114 can be equal; or the central angles between the adjacent folding portions 114 can be unequal. In the embodiment, the equal central angles between the adjacent folding portions 114 are mainly taken as an example for description.

[0063] In this way, it is beneficial to ensure the regular arrangement of the folding portions 114, and to bend each folding portion 114 at an equal angle to the axial direction, so that the shedding of the active material during the flattening process can be maximally reduced, and the deformation of the tabs can be avoided; on the other hand, it is beneficial to ensure the stability of the bending position; on the other hand, it is also beneficial to the implementation of the process, and improves the appearance of the battery cell 100; on the other hand, a large pressure is not needed when flattening the tabs, the stress of the bent tabs can be reduced, and the quality of the battery is ensured.

[0064] In order to further optimize the arrangement of the tabs, in an embodiment that can be implemented, referring to FIGS. 5 to 9, the folding directions of the plurality of folding portions 114 relative to the central angle of the battery cell 100 can be the same; or the folding directions of the plurality of folding portions 114 relative to the central angle of the battery cell 100 can be different.

[0065] In the embodiment, the same folding directions of the plurality of folding portions 114 relative to the central angle of the battery cell 100 are mainly taken as an example for description. In this way, it is beneficial to ensure the regular arrangement of the folding portions 114, so that the shedding of the active material during the flattening process can be maximally reduced, and the deformation of the tabs can be avoided; on the other hand, it is beneficial to ensure the stability of the bending position; on the other hand, it is also beneficial to the implementation of the process, and improves the appearance of the battery cell 100; on the other hand, a large pressure is not needed when flattening the tabs, the stress of the bent tabs can be reduced, and the quality of the battery is ensured.

[0066] In an implementation, as shown in FIG. 6, the folding part 114 has at least two, and the folding part 114 has a shaped included angle A, and the shaped included angle A is in a range of 5-180°. For example, the shaped included angle A is 5°, 100°, 150°, 180°, or any value in a range of 5-180°. The present embodiment is not limited in this regard. In this way, the end face of the battery cell after folding the tab is more flat.

[0067] It should be noted that when the end face of the battery cell is circular, the shaped included angle A of the folding part 114 can be a central angle, wherein the central angle is an included angle between two radii. Alternatively, when the end face of the battery cell is a regular polygon, the shaped included angle A of the folding part 114 can be a central angle, wherein the central angle is a central angle of a circumscribed circle of each side of the regular polygon. The present embodiment is not limited in this regard.

[0068] In an implementation, as shown in FIG. 6, the adjacent two shaped planes forming the folding part 114 have a shaped avoidance area, and the shaped avoidance area has an included angle B, and the included angle B is in a range of 0-5°. For example, the shaped avoidance area has an included angle B of 0°, 1°, 2°, 3°, 4°, 5°, or any value in a range of 0-5°. The present embodiment is not limited in this regard.

[0069] If the shaped avoidance area has an included angle B less than 0°, or the shaped avoidance area has an included angle B greater than 5°, the intermittent triangular convex structure cannot be well formed during the two times of side pushing forming. Therefore, the present disclosure limits the shaped avoidance area to have an included angle B in a range of 0-5°, which not only helps to ensure that the end face of the battery cell after folding the tab is more flat, but also naturally forms the intermittent triangular convex structure.

[0070] It should be noted that when the end face of the battery cell is circular, the shaped included angle A of the folding part 114 can be a central angle, wherein the central angle is an included angle between two radii. Alternatively, when the end face of the battery cell is a regular polygon, the shaped included angle A of the folding part 114 can be a central angle, wherein the central angle is a central angle of a circumscribed circle of each side of the regular polygon. The present embodiment is not limited in this regard.

[0071] In an implementation, as shown in FIG. 4, the empty foil area 112 can include a first reserved section 1121, a transition section 1122, and a tab section 1123, which are sequentially arranged along the length direction of the tab 110, and the first reserved section 1121 is located at the inner side of the winding of the battery cell 100.

[0072] In the embodiment of the present disclosure, the first reserved section 1121 is a non-tab area. This design takes into account the ductility of the pole piece 110 during the rolling process, which helps to avoid wrinkles and breakage of the pole piece 110 during rolling and winding. In addition, it also helps to easily remove the adhesive film after rolling without affecting the performance of the pole piece 110, improving the processing quality of the pole piece 110, and also helps to ensure the performance and safety of the battery. In the embodiment of the present disclosure, the tab section 1123 is the area where the tab is bent to form.

[0073] In the embodiment of the present disclosure, referring to FIG. 4, the height of the tab section 1123 is greater than the height of the first reserved section 1121. This is because the tab 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 tab section 1123 can ensure that the tab has enough space inside the battery to facilitate 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 tab section 1123, the distribution of electrolyte inside the battery can be optimized, avoiding the decline in 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, avoiding the phenomenon of wrinkles and bulges on the surface of the battery packaging bag caused by electrolyte overflow, thereby improving the yield of the battery.

[0074] It should be noted that the height difference between the tab section 1123 and the first reserved section 1121 is not limited, and can be set according to actual needs.

[0075] In the embodiment of the present disclosure, referring to FIG. 4, 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 empty foil area 112 from blocking the winding needle hole when it is bent and flattened during winding, thereby ensuring the smooth bending of the empty foil area 112. The inclination angle of the transition section 1122 is not limited, and can be set according to actual needs.

[0076] In an implementable embodiment, referring to FIG. 4, the side of the first reserved section 1121 away from the coating area 111 is flush with the bending line 113. This design improves the power characteristics of the battery from the tab angle, the current flows through a short distance, the current density distribution is uniform at high rate, high power density can be achieved, and the pole piece 110 also generates less heat, which not only optimizes the performance of the battery, but also improves the safety and reliability of the battery.

[0077] In the embodiments of the present disclosure, the length of the first reserved section 1121 in the length direction of the pole piece 110 is greater than or equal to 10 mm and less than or equal to 500 mm. For example, 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, and the embodiments are not limited in this regard.

[0078] In this way, on the one hand, it helps to avoid the problem that when the length of the first reserved section 1121 is too small, the pole piece 110 cannot be well prevented from being wrinkled and broken during rolling and winding; on the other hand, it helps to avoid the problem that when the length of the first reserved section 1121 is too large, the length of the tab section 1123 is affected, thereby helping to ensure that the tab has enough space inside the battery, to ensure smooth flow of current during battery charging and discharging, to optimize the distribution of current inside the battery, to reduce internal resistance, and thereby to improve the energy conversion efficiency and service life of the battery.

[0079] In an implementable embodiment, the height of the tab section 1123 along the bent portion of the bending line 113 is greater than or equal to 2 mm and less than or equal to 8 mm. For example, the height of the tab section 1123 can be 2 mm, 3 mm, 4 mm, 6 mm, 8 mm, or any value between 2 mm and 8 mm. The embodiments are not limited in this regard.

[0080] In this way, it helps to ensure that the height of the tab section 1123 is within a reasonable range, thereby ensuring that the tab has enough space inside the battery during the winding process of the battery, to facilitate smooth flow of current during battery charging and discharging, to optimize the distribution of current inside the battery, to reduce internal resistance, and thereby to improve the energy conversion efficiency and service life of the battery; in addition, the distribution of electrolyte inside the battery can be optimized, and the performance degradation of the battery caused by uneven distribution of electrolyte can be avoided.

[0081] In an implementable embodiment, referring to FIG. 4, the empty foil area 112 can further include a second reserved section 1124, the second reserved section 1124 being connected with the tab section 1123; the second reserved section 1124 is located on the outside of the winding of the battery cell 100, and the side edge of the second reserved section 1124 away from the coating area 111 is flush with the bending line 113.

[0082] In the embodiments of the present disclosure, the second reserved section 1124 is a tab-free area. In this way, the design helps to shorten the distance of current flow, thereby achieving uniformity of current density distribution at high power density, and thereby achieving high power density; in addition, this design can also reduce the heat generation of the pole piece 110, and improve the performance and safety of the battery.

[0083] In the embodiment of the present disclosure, the side edge 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 tab, the current flows through a short distance, the current density distribution is uniform at a large rate, high power density can be achieved, and the heat generated by the tab 110 is small, which not only optimizes the performance of the battery, but also improves the safety and reliability of the battery.

[0084] In an implementable embodiment, referring to FIG. 4, the bending line 113 extends along the length direction of the tab 110, the empty foil area 112 forms a buffer area 115 and a bending area 116 on both sides of the bending line 113, the buffer area 115 is connected with 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.

[0085] In the embodiment of the present disclosure, by including the buffer area 115, on the one hand, it helps to increase the buffer area 115 of the empty foil area 112 at the tab position, thereby helping to increase the stress buffer area 115 of the tab empty foil area 112, and to the greatest extent protect the tab from breaking due to external reasons; on the other hand, it can prevent the tab 110 from breaking due to stress generated during the thickness change of the tab 110 during the charging and discharging of the battery, and to the greatest extent protect the safety performance of the battery.

[0086] It should be noted that the size and shape of the buffer area 115 and the bending area 116 are not limited, and can be set as needed.

[0087] In an implementable embodiment, referring to FIG. 4, 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 a wicking channel between the two sides of the empty foil area 112.

[0088] It should be noted that the present disclosure can also not process the immersion hole 1161, which helps to retain the integrity of the empty foil area 112, and the electrolyte can enter from the gap of the tab bending during liquid injection, which is not limited in the present embodiment.

[0089] In the embodiment of the present disclosure, the processing method of the immersion hole 1161 is not limited. For example, the immersion hole 1161 can be processed by laser die cutting, which is not limited in the present embodiment. In addition, the shape, number and size of the immersion hole 1161 are not limited, and can be set as needed.

[0090] In the embodiment of the present disclosure, the immersion hole 1161 is provided in the buffer area 115, which does not interfere with the normal bending of the bending area 116, and helps to ensure the structural integrity of the bending area 116.

[0091] In this way, by processing the immersion hole 1161, on the one hand, it helps to increase the contact area of the pole piece 110 with the electrolyte, so that the electrochemical reaction is more sufficient, thereby improving the capacity and energy density of the battery; on the other hand, the immersion hole 1161 can form an ion channel, shorten the migration distance of ions in the pole piece 110, thereby improving the charge and discharge rate of the battery; on the other hand, during the charging and discharging process, due to the volume change of the active material, processing the immersion hole 1161 can alleviate this volume effect and prevent the destruction of the structure of the pole piece 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 pole piece 110, which is conducive to the dissipation of heat generated by the battery during operation, thereby improving the thermal stability of the battery.

[0092] In an implementation that can be implemented, 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. Exemplarily, 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 does not limit this.

[0093] In this way, it helps to ensure that the diameter of the immersion hole 1161 is within a suitable range, on the one hand, it helps to avoid the problem that when the diameter of the immersion hole 1161 is too small, the contact area of the pole piece 110 with the electrolyte is too small, and the electrochemical reaction is not sufficient; on the other hand, it also helps to avoid the problem that when the diameter of the immersion hole 1161 is too large, it may cause the electrolyte to flow out and affect the performance of the battery.

[0094] Referring to FIG. 10, the present disclosure provides a method for manufacturing a battery cell, for preparing a battery cell, the method comprising:

[0095] S100: winding the pole piece and bending the empty foil area of the end portion of the pole piece in the direction from the outer arc surface of the battery cell to the center of the battery cell.

[0096] Wherein, during the winding of the pole piece, the winding can be carried out by the axial direction of the winding needle. Exemplarily, the winding needle can be understood as a winding shaft, in this way, it is conducive to winding and plays a supporting and fixing role during winding to maintain stability during winding.

[0097] S200: flattening the bent empty foil area of the end portion of the battery cell to form a plane.

[0098] Wherein, during the flattening, a flattening structure can be used for flattening. Exemplarily, the flattening structure can be a flattening air cylinder, and this embodiment does not limit this.

[0099] In this way, after winding is completed, the flat structure is used to flatten the empty foil area 112 and the folded part 114, so as to realize a flat welding plane of the current collector plate. The structure after flattening is shown in FIG. 9.

[0100] It should be noted that the plane formed in the embodiment can be understood as a relatively flat plane.

[0101] In an implementable embodiment, the pole piece is a continuous structure, and in the step of winding the pole piece, the method can further include:

[0102] In the winding process, the pole piece end is bent along the direction from the outer arc surface of the battery cell to the center of the battery cell, and the empty foil area at the pole piece end forms a plurality of protruding parts and folded parts spaced along the winding direction;

[0103] The protruding parts at the pole piece end are rolled to make the protruding parts fold relative to the already bent empty foil area and form a plane.

[0104] In the embodiment, the shape of the protruding part 117 is not limited, and for example, the shape of the protruding part 117 can be a triangular protrusion, or the shape of the protruding part 117 can be a polygonal protrusion, or the shape of the protruding part 117 can be other shapes. In the embodiment, the shape of the protruding part 117 is mainly taken as a triangular protrusion for illustration.

[0105] The disclosure also provides a forming device in the embodiment, which can include a folding mechanism and a rolling mechanism to realize the battery cell manufacturing method of the third embodiment.

[0106] The folding mechanism 200 is used to form the folded part 114 at the empty foil area 112 at the pole piece end. In the process of bending along the direction from 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:

[0107] One bending manner is that, as shown in FIGS. 5 and 6, the folding mechanism 200 bends one by one along the direction from the outer arc surface of the battery cell to the center of the battery cell. Specifically, the foil material parallel to the axis of the battery cell 100 is run from the outer side of the battery cell 100 to the axis direction, and is bent one by one at an interval of 60-90° or at an equal included angle towards the axis. The bending angle is not limited. For example, the foil material can be bent one by one at an interval of 60° or at an equal included angle; or the foil material can be bent one by one at an interval of 70° or at an equal included angle; or the foil material can be bent one by one at an interval of 90° or at an equal included angle. The embodiment does not limit this, and the folding direction can be set according to actual needs. For example, the folding direction of the embodiment can be shown in the direction of the arrow a in FIG. 6.

[0108] Another bending mode is shown in FIGS. 5 and 6. The folding mechanism 200 is rolled and pressed in the 360° direction of the outer arc of the battery cell. Specifically, the folding mechanism 200 is rolled and pressed in the 360° direction of the outer arc of the battery cell, 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 the present embodiment can be shown by the arrow b direction in FIG. 6.

[0109] It should be noted that the bending mode of the empty foil area 112 in the present embodiment includes but is not limited to the above-mentioned mode, and can be set according to actual needs.

[0110] In this way, as shown in FIGS. 7 and 8, the folding part 114 of the intermittent foil tab is achieved by rolling and pressing the intermittent triangular protrusion on one side, and the folding part 114 of the intermittent tab foil is formed by layer-by-layer winding of the tab 110, and finally the folding part 114 is formed on the end face of the battery cell 100, and the outer tab foil area wraps the inner tab of the battery cell.

[0111] It should be noted that before step S100, when the battery cell 100 is being manufactured, the edge foil of the active material of the inner ring of the tab 110 is reserved with a certain length of non-tab area (first reserved section in the present disclosure), and a foil area with increasing slope (transition section in the present disclosure) is designed to prevent the foil area from blocking the pinhole during winding and pressing. The edge of the tab 110 in the middle of the battery cell 100 is reserved with a complete foil area (tab section in the present disclosure), and the tail of the tab 110 is reserved with a non-tab area (second reserved section in the present disclosure) with an unfolded length of 0-5 turns of the tab 110.

[0112] It should be noted that after step S300, a buffer area 115 with empty foil is reserved between the bent tab and the coating area 111, and the present disclosure designs a laser die-cut immersion hole 1161 for liquid injection. In the longitudinal layout of the tab 110, the immersion channel is formed in the radial direction of the battery cell 100 after winding.

[0113] In the step of rolling and pressing the folding mechanism 200 at the end of the tab to form the folding part, the two sides of the folding mechanism 200 can be parallel, or the two sides of the folding mechanism 200 can have an included angle C, and the included angle C can be between 0-5°.

[0114] For example, as shown in FIG. 6, the included 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 is helpful to improve the flatness of the end face of the battery cell after the tab is folded, and to maximize the quality of the battery.

[0115] In the embodiments of the present disclosure, after the folding mechanism 200 is bent, a rolling mechanism 300 can be further included, which is used to roll the protruding part 117 at the end of the pole piece to fold and form a flat surface with respect to the already bent hollow foil area 112. For example, the rolling mechanism 300 can roll in the direction of the arrow in FIG. 8.

[0116] It should be noted that, since there is excess material during the rolling process, the folding and forming a flat surface in the present embodiment is not an absolutely flat surface.

[0117] Therefore, the embodiments of the present disclosure provide an electric core, a battery, a manufacturing method of an electric core and a forming device, which include pole pieces and a diaphragm, and the diaphragm is clamped between two pole pieces, which helps to prevent short circuit caused by direct contact between the positive and negative pole pieces and ensures the safety performance of the battery. The hollow foil area is bent to the winding center to form a tab, the tab has a folding part arranged at intervals, the folding part is pressed and overlapped to the surface of the tab, and a welding surface is formed at the end of the electric core. In this way, the present disclosure optimizes the arrangement mode of the tab, forms a regular arranged welding plane at the end of the electric core, thereby helping to reduce the shedding of active material during the flattening process, avoiding the deformation of the tab, improving the short circuit defect, reducing the manufacturing difficulty; at the same time, it helps to reduce the manufacturing cost of the laser cutting and overlapping structure electric core, reduce the welding difficulty, and maximize the quality of the battery.

[0118] It should be noted that, in the description of the embodiments of the present disclosure, unless otherwise explicitly specified and limited, the terms “mounting”, “connection”, “connection” should be understood in a broad sense, for example, it can be fixedly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present disclosure can be understood according to the specific circumstances.

[0119] In the description of the embodiments of the present disclosure, the term “and / or” only represents an association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B, which can represent three cases of A alone, A and B together, and B alone. In addition, the term “at least one” means any combination of any one or at least two of the plurality, for example, including at least one of A, B, and C, which can represent any one or more elements selected from the set of A, B, and C.

[0120] In the description of the embodiments of the present disclosure, the terms "upper", "lower", "front", "back", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present disclosure and simplify the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation to the present disclosure. In addition, the term "a plurality of" means two or more, unless otherwise specifically specified.

[0121] In the description of the embodiments of the present disclosure, the terms "first", "second", "third", "fourth" and the like (if any) are used to distinguish similar objects, and do not necessarily have to describe a particular order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present disclosure described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device that includes a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0122] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present disclosure, and not to limit them; although the present disclosure has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. An electric cell, comprising: a pole piece (110), the pole piece (110) comprising a coated area (111) and an empty foil area (112), the empty foil area (112) being located at an end of the coated area (111) along a winding axis of the pole piece (110); a separator, the separator being sandwiched between two pole pieces (110), the pole pieces (110) and the separator being co-wound together; the empty foil area (112) is bent relative to the coated area (111) and forms a tab, the tab having a plurality of folding portions (114), the plurality of folding portions (114) being arranged along a winding direction of the pole piece (110), each of the folding portions (114) being folded relative to an end surface of the electric cell.

2. The electric cell according to claim 1, the plurality of folding portions (114) being folded towards a winding core direction.

3. The electric cell according to claim 1 or 2, a distance between adjacent folding portions (114) is equal; or, a central angle between adjacent folding portions (114) is equal.

4. The electric cell according to any one of claims 1-3, having at least two folding portions (114), each of the folding portions (114) having a shaped included angle A therebetween, the shaped included angle A being in a range of 5-180°.

5. The electric cell according to any one of claims 1-4, having a shaped avoidance area in two adjacent shaped planes forming the folding portions (114), the shaped avoidance area having an included angle B, the included angle B being in a range of 0-5°.

6. The electric cell according to any one of claims 1-5, the empty foil area (112) having a bending line (113), the empty foil area (112) being bent relative to the coated area (111) along the bending line (113) towards a winding center of the electric cell and forming the tab.

7. The electric cell according to claim 6, the empty foil area (112) comprising a first reserved section (1121), a transition section (1122) and a tab section (1123), the first reserved section (1121), the transition section (1122) and the tab section (1123) being sequentially arranged along a length direction of the pole piece (110), the first reserved section (1121) being located at an inner side of the electric cell winding; a height of the tab section (1123) is greater than a height of the first reserved section (1121), a side of the transition section (1122) being obliquely arranged relative to the length direction of the pole piece (110).

8. The electric cell according to claim 7, a side of the first reserved section (1121) facing away from the coated area (111) being flush with the bending line (113); and / or, a 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 electric cell according to claim 7 or 8, a height dimension of the tab section (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 of any one of claims 7-9, wherein the empty foil area (112) further comprises a second reserved section (1124) connected to the tab section (1123); the second reserved section (1124) is located at the outer side of the battery cell winding, and the side edge of the second reserved section (1124) away from the coated area (111) is flush with the bending line (113).

11. The battery cell of claim 6, wherein the bending line (113) extends along the length direction of the electrode tab (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 coated area (111), and the bending area (116) is located at the side of the buffer area (115) away from the coated area (111); the empty foil area (112) is configured to bend the bending area (116) relative to the coated area (111) along the bending line (113).

12. The battery cell of claim 11, wherein the buffer area (115) is provided with a plurality of spaced immersion holes (1161) configured to form a wicking channel between the two sides of the empty foil area (112).

13. The battery cell of claim 12, wherein 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 comprising the battery cell of any one of claims 1-13.

15. A battery cell manufacturing method for preparing the battery cell of any one of claims 1-13; the method comprising: winding the electrode tab and bending the empty foil area of the electrode tab end along the direction from the outer arc surface of the battery cell to the center of the battery cell; flattening the bent empty foil area of the battery cell end to form a flat surface.

16. The battery cell manufacturing method of claim 15, wherein the electrode tab is a continuous structure, and the winding step further comprises: during winding, bending the empty foil area of the electrode tab end along the direction from the outer arc surface of the battery cell to the center of the battery cell to form a plurality of protrusions and folds spaced along the winding direction; rolling the protrusions at the electrode tab end to fold the protrusions relative to the already bent empty foil area and form a flat surface.

17. A forming device comprising a folding mechanism and a rolling mechanism to implement the battery cell manufacturing method of claim 15 or 16.

18. The forming device of claim 17, wherein the folding mechanism is configured to form a fold at the empty foil area of the electrode tab end; wherein, the folding mechanism is configured to bend one by one along the direction from the outer arc surface of the battery cell to the center of the battery cell; or, the folding mechanism is configured to perform 360° rolling type bending in the direction of the outer arc surface of the battery cell.

19. The forming device of claim 18, wherein the two side edges of the folding mechanism are parallel; or, the folding mechanism has an included angle C between the two side edges, and the included angle C ranges from 0-5°. ​ 20. The forming apparatus of claim 18 or 19, the roller press mechanism being configured to roll a protrusion at an end of a pole piece to fold and form a flat with respect to a blanked foil region that has already been bent.

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