Pole piece, roll core, preparation method of roll core, battery cell and battery pack

Abstract

The invention provides a pole piece, a roll core, a preparation method of the roll core, a battery cell and a battery pack. The roll core comprises a body (1), tabs are arranged at the ends of the body (1), the body (1) comprises a wound pole piece main body (2), the tabs are folded at the winding position of the pole piece main body (2) along with winding of the pole piece main body (2), and two segments (3) connected at the winding position of the pole piece main body (2) are formed. The roll core can effectively prevent the tabs from being folded and warped, and the welding quality of the tabs is effectively guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy battery, in particular to a pole piece, a roll core, a preparation method thereof, a battery cell and a battery pack. BACKGROUND

[0002] Lithium-ion batteries play an important role in portable electronic devices, electric vehicles, and grid energy storage systems due to their high energy density, long lifespan, and excellent cycle performance. As a mainstream packaging form of lithium-ion batteries, square batteries have a precise and complex internal structure, mainly including positive pole pieces, negative pole pieces, electrolytes, and separators. Among them, the positive pole pieces and the negative pole pieces are connected to the external circuit through the tabs, while the electrolytes and the separators are used to ensure the stable progress of the electrochemical reaction. The performance and reliability of the battery depend largely on the fine design of the internal structure, especially the design and manufacturing accuracy of the tabs.

[0003] In the internal structure of the square lithium-ion battery, the positive pole piece is composed of a positive active material layer and a current collector (usually aluminum foil), and the negative pole piece is composed of a negative active material layer and a current collector (usually copper foil). The edges of the pole pieces are usually cut out to form tabs for connecting the external circuit. These tabs are stacked in a specific order during the winding of the battery roll core and are finally fixed on the side of the battery.

[0004] In the traditional structure of the square battery, the tabs are usually located on one side of the roll core opening and are composed of multiple layers of easily deformable foils. These foil layers rely only on the adhesion between the pole pieces to maintain their position during the winding of the roll core, and there is no direct physical connection between them. This makes the tabs prone to folding or warping during subsequent manufacturing processes such as roll core transfer, positioning, and ultrasonic welding. The folding or warping of the tabs not only increases the difficulty of size detection, but also may cause poor contact between the upper and lower tabs during the ultrasonic welding process, resulting in virtual welding or missed welding problems, which directly affects the electrical performance and product quality of the battery.

[0005] To address the challenges posed by tab folding and warping, various auxiliary equipment and methods have been introduced into the traditional manufacturing process, such as using a CCD vision detection system for size and shape detection, and using a tab flattening mechanism to reshape the warped tabs. Although the CCD detection system can provide high-precision position and shape information, due to the reflective nature of the tab material and the complex stacking structure, the detection algorithm has difficulty accurately distinguishing between normal and abnormal states, especially in the case of slight folding or warping, the misjudgment rate is relatively high. This not only affects the accuracy of detection, but also increases the detection time and cost, reducing production efficiency.

[0006] On the other hand, the design of the tab flattening mechanism is to flatten the warped tab by mechanical force to ensure the smooth progress of the subsequent welding process. However, the characteristics of the foil itself determine that the flattened tab may still deform again due to elastic rebound, which limits the shaping effect of the flattening mechanism and cannot guarantee the flatness of the tab in the subsequent welding process, resulting in a decline in welding quality, which in turn affects the performance and durability of the battery.

[0007] Therefore, the square battery in the prior art generally cannot effectively prevent the tab from folding and warping during the core manufacturing process, which leads to the problem of being unable to effectively guarantee the welding quality of the tab. SUMMARY

[0008] The main purpose of the present application is to provide a tab, a core and a preparation method thereof, a battery cell and a battery pack, which can effectively prevent the tab from folding and warping, and effectively guarantee the welding quality of the tab.

[0009] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a core is provided, comprising a body, the end of the body is provided with a tab, the body comprises a wound tab body, each tab is folded with the winding of the tab body at the winding position of the tab body, and forms two segments connected at the winding position of the tab body. It can be guaranteed that each layer of tab can form good fitting effect and deformation prevention effect, avoiding the folding and warping of the tab during manufacturing and assembling, ensuring the positioning accuracy and structural stability of the tab inside the core, thereby significantly improving the precision of the subsequent welding process and the electrical performance of the battery, and reducing the defective rate in the production process.

[0010] Further, the tab is provided with a through hole on the side close to the tab body, the through hole is located at the folding position of the tab, and the through hole does not penetrate the tab along the folding direction of the tab. Prevents material fatigue and fracture caused by the tab during welding and assembly, and ensures the long-term electrical performance and structural reliability of the tab.

[0011] Further, along the direction from the inside to the outside of the core, the width of the through hole increases. It is more convenient to perform subsequent welding and assembly operations, and the stress generated during welding and assembly can be more effectively released, effectively avoiding cracks or fractures of the tab during welding and assembly.

[0012] Further, each tab of the same pole is superimposed, the through holes are superimposed to form an opening slot opening to the outer edge of the core, and the groove bottom of the opening slot is flush. The stress can be effectively released through the opening slot, the integrity of the tab is maintained, the welding quality and the yield of battery manufacturing are improved, and the reliability of electrical connection is improved as a whole.

[0013] Further, the through hole and the tab body have a preset interval. The difficulty of processing the through hole on the tab is reduced, the damage to the structure of the tab body in the process of processing the through hole is effectively avoided, and the processing efficiency is improved.

[0014] Further, along the direction from the inside to the outside of the winding core, the width of the tab in the winding direction increases. The internal stress is reduced, the tab is prevented from being folded or warped in the subsequent assembly process, and the high yield and excellent performance of the battery manufacturing are ensured.

[0015] Further, the tabs of the same pole are stacked and flush on the side away from the outer edge of the winding core. The flush design reduces the space occupation in the winding core, helps the compactness of the overall structure, and optimizes the energy density of the battery.

[0016] Further, the tab is rectangular or trapezoidal in projection along the stacking direction of the tab body, and when the tab is trapezoidal, the width of the tab decreases in the direction away from the tab body. Effectively adapt to the material deformation in the winding process, reduce the probability of tab wrinkling and folding risk in the winding process, and ensure the close fit and stable connection of the tab when stacking.

[0017] Further, the tab includes a positive tab and a negative tab, and the positive tab and the negative tab are located at the same end of the body, or the positive tab and the negative tab are located at different ends of the body. The difficulty of forming the winding core can be reduced, and the forming and assembly efficiency can be improved.

[0018] Further, the tab is gathered at the middle position of the stacking direction of the tab body. The double winding core parallel assembly process can be simplified, the complexity of traditional A / B winding core pairing is avoided, and the production cost and process difficulty are reduced.

[0019] According to another aspect of the present application, a preparation method of the above-mentioned winding core is provided, comprising:

[0020] Preparation of positive tab, separator and negative tab;

[0021] Stacking the positive tab, the separator and the negative tab to form a to-be-wound structure;

[0022] Winding the to-be-wound structure so that the positive tab and the negative tab are located at the winding position of the to-be-wound structure and are folded with the winding of the to-be-wound structure. The winding stress is effectively dispersed, the disorder warping or damage of the tab is avoided, the reliability of the subsequent welding process is ensured, and the yield of the battery manufacturing and the electrical performance stability of the final product are improved.

[0023] Further, the step of preparing the positive tab, the separator and the negative tab comprises:

[0024] A through hole is processed at the tab root of the positive electrode tab, so that the through hole extends along the length direction of the positive electrode tab and does not penetrate the two ends of the tab along the length direction;

[0025] A through hole is processed at the tab root of the negative electrode tab, so that the through hole extends along the length direction of the negative electrode tab and does not penetrate the two ends of the tab along the length direction. Not only is the tab stacking state structurally stable, but also stress can be effectively released through the open slot during subsequent welding assembly, maintaining the integrity of the tab, improving welding quality and battery manufacturing yield.

[0026] Further, the preparation method further comprises:

[0027] All the positive electrode tabs are gathered and fused so that the positive electrode tabs are located at the center position in the thickness direction of the winding core;

[0028] All the negative electrode tabs are gathered and fused so that the negative electrode tabs are located at the center position in the thickness direction of the winding core. The feature of the tab being located at the center position simplifies the parallel assembly process of the double winding core, and only two identical winding cores are needed for pairing during the parallel pairing process of the double winding core, without the need to manufacture A / B two different winding cores, greatly reducing the manufacturing complexity.

[0029] According to another aspect of the present application, a tab is provided for use in the winding core or the preparation method of the winding core, comprising:

[0030] The tab body has a coating area;

[0031] The active material is coated on the coating area of the tab body;

[0032] The tab is arranged on one side of the tab body along the width direction of the tab body, and the tab is provided with a through hole near one side of the tab body, and the through hole does not penetrate the tab at the two ends along the length direction of the tab body. The folding path and form of the tab can be effectively controlled, the folding difficulty of the tab is reduced, the tab is naturally gathered at the center position in the thickness direction of the winding core, and the tab plays a role in stress release during winding and battery assembly, reduces internal stress accumulation caused by material deformation, and enhances the mechanical stability and electrical consistency of the battery.

[0033] Further, the through hole has a predetermined interval with the tab body. The difficulty of processing the through hole on the tab is reduced, and damage to the structure of the tab body during processing of the through hole can be effectively avoided, and the processing efficiency is improved.

[0034] Further, along the winding direction of the pole piece, starting from the starting end, the length of the through hole increases; and / or, the length of the tab increases. This facilitates subsequent welding assembly operations, and can more effectively release stress generated during welding assembly, effectively avoiding cracks or breakage of the tab during welding assembly.

[0035] Further, the pole piece includes a positive pole piece and a negative pole piece, and the tab includes a positive tab and a negative tab. The positive pole piece includes the positive tab, and the negative pole piece includes the negative tab. The dimension of the negative tab along the length direction of the pole piece body is Tf, the dimension of the positive tab along the length direction of the pole piece body is Tz, the interval between the positive tab and the negative tab in the same layer is S, the interval between two adjacent negative tabs in different layers and along the winding direction is 2S+Tz, and the interval between two adjacent positive tabs in different layers and along the winding direction is 2S+Tf. This effectively avoids tab overlap and interference, promotes natural formation of the U-shaped folding, ensures stable folding of the tab at the center of the thickness of the winding core, and provides a good foundation for subsequent welding procedures.

[0036] Further, the pole piece includes a positive pole piece and a negative pole piece, and the tab includes a positive tab and a negative tab. The positive pole piece includes the positive tab, and the negative pole piece includes the negative tab. The tab includes the positive tab and the negative tab, the dimension of the negative tab along the length direction of the pole piece body is Tf, the dimension of the positive tab along the length direction of the pole piece body is Tz, the interval between the positive tab and the negative tab in the same layer is S, and the interval between the positive tab and the negative tab in different layers and along the winding direction is K, where K=n*(3*S+Tf+Tz), and n is a positive integer. This can control the interval between tabs in different layers, reduce the number of layers of the tab, thereby reducing the difficulty of tab pre-welding and welding of the tab and the connecting piece, reducing the occurrence of virtual welding and other adverse phenomena, and improving welding quality.

[0037] According to another aspect of the present application, an electric core is provided, including the winding core.

[0038] According to another aspect of the present application, a battery pack is provided, including the winding core or the electric core.

[0039] The application has the advantages that the tab of the body end of the core is designed to be dynamically folded during the winding process of the tab body, and finally two stably connected segments are formed at the winding position. The two segments formed by folding are still of an integrated structure, which can ensure that the two segments originally integrated remain in a connected state, and under the action of folding, the folding force generated by bending forms a more effective anti-folding and anti-warping structure. In addition, due to the layer-by-layer wrapping structure of the tab, the two segments on the outside can use the connection effect of the folding structure at the winding position to form a folding and clamping effect on the multiple segments on the inside, so that each layer of the tab can form a good fitting effect and anti-deformation effect, avoiding the folding and warping of the tab during the manufacturing and assembly process, ensuring the positioning accuracy and structural stability of the tab inside the core, thereby significantly improving the precision of the subsequent welding process and the electrical performance of the battery, and reducing the defect rate in the production process. BRIEF DESCRIPTION OF DRAWINGS

[0040] The drawings accompanying the specification of this application form a part thereof, serve to provide further understanding of the application, and together with the description of the application, explain the application. The detailed description of the application and its illustrations serve to explain the application without imposing undue limitation on the application. In the drawings:

[0041] Figure 1 is a structural schematic diagram of the positive and negative tabs of the first embodiment of the application;

[0042] Figure 2 is a structural schematic diagram of the core of the first embodiment of the application;

[0043] Figure 3 is a side view structural schematic diagram of the core of the first embodiment of the application;

[0044] Figure 4 is a three-dimensional structural schematic diagram of the core of the first embodiment of the application;

[0045] Figure 5 is a three-dimensional structural schematic diagram of the core of the first embodiment of the application after the tab folding and pre-welding;

[0046] Figure 6 is a structural schematic diagram of the core of the first embodiment of the application after the tab folding and pre-welding;

[0047] Figure 7 is a three-dimensional connection structure diagram of the connecting tab and the tab of the core of the first embodiment of the application;

[0048] Figure 8 is a connection structure diagram of the connecting tab and the tab of the core of the first embodiment of the application;

[0049] Figure 9 is a connection structure diagram of the core and the cover plate assembly of the first embodiment of the application;

[0050] Figure 10 is a side view of the connecting structure of the roll core and the cover plate assembly of the first embodiment of the application;

[0051] Figure 11 is a perspective view of the connecting structure of the roll core and the cover plate assembly of the first embodiment of the application;

[0052] Figure 12 is a connecting structure diagram of the roll core and the cover plate assembly of the first embodiment of the application;

[0053] Figure 13 is a partial enlarged view of the connecting structure of the roll core and the cover plate assembly of the first embodiment of the application;

[0054] Figure 14 is a structural schematic diagram of the positive electrode sheet and the negative electrode sheet of the second embodiment of the application;

[0055] Figure 15 is a structural schematic diagram of the positive electrode sheet and the negative electrode sheet of the third embodiment of the application;

[0056] Figure 16 is a structural schematic diagram of the roll core of the third embodiment of the application;

[0057] Figure 17 is a perspective structural schematic diagram of the roll core of the third embodiment of the application;

[0058] Figure 18 is a structural schematic diagram of the roll core of the fourth embodiment of the application;

[0059] Figure 19 is a perspective structural schematic diagram of the roll core of the fourth embodiment of the application;

[0060] Figure 20 is a perspective structural schematic diagram of the roll core after splicing of the fourth embodiment of the application;

[0061] Figure 21 is a structural schematic diagram of the roll core after splicing of the fourth embodiment of the application;

[0062] Figure 22 is a perspective structural schematic diagram of the cover plate assembly of the fourth embodiment of the application;

[0063] Figure 23 is a perspective structural schematic diagram of the cover plate assembly of the fourth embodiment of the application from another perspective;

[0064] Figure 24 is a perspective structural diagram of the tab of the roll core and the cover plate assembly after completion of welding of the fourth embodiment of the application;

[0065] Figure 25is a structure diagram of the tab and the cover plate assembly of the winding core after welding of the fourth embodiment of the application is completed;

[0066] Figure 26 is a structure diagram of the winding core of the fifth embodiment of the application;

[0067] Figure 27 is a three-dimensional structure diagram of the tab and the connecting piece of the winding core after welding of the fifth embodiment of the application is completed;

[0068] Figure 28 is a structure diagram of the connecting piece and the cover plate assembly after welding of the fifth embodiment of the application is completed;

[0069] Figure 29 is a three-dimensional structure diagram of the connecting piece and the cover plate assembly after welding of the fifth embodiment of the application is completed;

[0070] Figure 30 is a three-dimensional structure diagram of the cover plate assembly and the shell after welding of the fifth embodiment of the application is completed;

[0071] Figure 31 is Figure 30 a sectional structure diagram of A-A direction.

[0072] Among them, the above-mentioned drawings include the following reference signs:

[0073] 1, the body; 10, the negative pole piece; 101, the negative pole ear; 2, the pole piece main body; 3, the segment; 20, the positive pole piece; 201, the positive pole ear; 30, the through hole; 40, the open slot; 50, the positive pole connecting piece; 60, the negative pole connecting piece; 70, the cover plate assembly: 701, the positive pole support, 702, the negative pole support; 80, the shell. DETAILED DESCRIPTION

[0074] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0075] Combined with the drawings shown in Figures 1 to 31 According to the embodiments of the present application, the winding core includes a body 1, the end of the body 1 is provided with a pole ear, the body 1 includes a wound pole piece main body 2, each pole ear is folded with the winding of the pole piece main body 2 at the winding position of the pole piece main body 2, and two segments 3 connected at the winding position of the pole piece main body 2 are formed.

[0076] In the present application, the tab at the end of the body 1 of the core is designed to be dynamically folded during the winding process of the tab body 2, and finally forms two stably connected segments 3 at the winding position. The two segments 3 formed by folding are still an integral structure, which can ensure that the two segments 3 originally integrated remain connected, and under the action of folding, the folding force generated by bending forms a more effective anti-folding and anti-warping structure. Moreover, due to the layer-by-layer wrapping structure of the tab, the two segments 3 located on the outside can use the connection effect formed by the folding structure at the winding position to form a folding and clamping effect on the multiple segments 3 located on the inside, thereby ensuring that each layer of tab can form a good fitting effect and anti-deformation effect, avoiding the folding and warping of the tab during manufacturing and assembly, and ensuring the positioning accuracy and structural stability of the tab inside the core, thereby significantly improving the precision of the subsequent welding process and the electrical performance of the battery, and reducing the defect rate in the production process.

[0077] The core of this design is to use the folding characteristics of the tab. By designing a foldable tab at the end of the core body 1, when the tab body 2 is wound, the tab is folded along with it, and two segments 3 are formed at the winding completion position. These two segments 3 are tightly connected to the winding position of the tab body 2, and can support each other, thereby effectively preventing the tab from freely warping and folding during subsequent processing. This design not only simplifies the layout of the tab inside the battery, but also reduces the alignment difficulty when the tab is welded with external connectors, providing favorable conditions for automation and high precision in the battery manufacturing process, ensuring the high quality and consistency of the battery.

[0078] This embodiment combines the structure design of the tab with the winding structure of the tab body 2, not only solving the problem of easy deformation of the traditional core tab, but also providing a new idea for optimizing the battery manufacturing process and improving the performance of the battery.

[0079] In this embodiment, since the tabs of the core are symmetrically arranged along the folding surface, the tabs are more convenient to move towards the middle position in the thickness direction of the core, so that the core can be folded at the center position in the thickness direction of the core after pre-welding. During the parallel pairing of double cores, only two identical cores are needed to realize the pairing operation, without the need to manufacture A / B two different cores, greatly reducing the manufacturing complexity. Here, the tabs are symmetrically arranged along the folding surface, which means that the positions of the tabs are symmetric along the folding surface, and the width is not limited to be symmetrical, that is, the structure is not limited to be completely symmetrical.

[0080] In one embodiment, the two segments 3 formed by the same tab are symmetrical about the folding plane where the winding center line of the multi-layer tab body 2 of the winding core is located, and the structures of the two segments 3 located on both sides of the folding plane are the same. During the winding process of the tab body 2 of the winding core, the tab is dynamically folded along the folding plane where the winding center line is located, which ensures the consistency and stability of the structure of the two segments 3 formed by the same tab, effectively overcomes the deformation problem of the tab, improves the precision of battery manufacturing, and ensures the reliability of electrical connection.

[0081] In one embodiment, the tab is provided with a through hole 30 on the side close to the tab body 2. The through hole 30 is located at the folding position of the tab, and the through hole 30 does not penetrate the tab along the folding direction of the tab, that is, does not penetrate the tab along the length direction of the tab. Here, the folding direction of the tab refers to the length direction of the tab body 2 before winding.

[0082] In this embodiment, the non-penetrating through hole 30 provided on the side close to the tab body 2 of the tab is located at the folding position, and the through hole 30 plays a role of stress release in the subsequent welding assembly process of the tab, effectively reduces the stress concentration at the folding position, avoids the damage of the tab material, ensures the integrity and stability of the tab in the subsequent assembly process, and thus improves the yield and electrical connection quality of battery manufacturing.

[0083] By providing the through hole 30 which does not penetrate the entire length direction of the tab at the folding position of the tab, the stress relaxation effect of the local material is ingeniously utilized to prevent material fatigue and fracture of the tab caused by welding assembly, and the long-term electrical performance and structural reliability of the tab are ensured.

[0084] In this embodiment, since the through hole 30 does not penetrate the tab along the length direction of the tab, the length direction of the tab is connected with the tab body 2 at both ends. When the tab is bent with the tab body 2, since the both ends of the tab are connected with the tab body 2, the structure of the tab is avoided to be loose, the structural strength of the tab at the bending position is ensured, the folding effect of the tab caused by bending is more effectively avoided in the subsequent transfer process, and the welding quality of the tab is improved. At the same time, due to the setting of the through hole 30, a weakened area can be formed at the bending position, which can effectively release the stress generated in the welding assembly process of the tab, and prevent cracks or fractures of the tab in the welding assembly process.

[0085] In one embodiment, along the direction from the inside to the outside of the winding core, the width of the through hole 30 increases.

[0086] Along the direction from inside to outside of the winding core, the tab forms a layer-by-layer wrapping structure, the farther the tab is located from the outer layer of the winding core, the longer the length of the arc-shaped winding structure required is, by increasing the width T of the through hole 30, the structure position of each layer of the through hole 30 far away from the edge position of the winding core can be made more consistent, and the subsequent welding assembly operation is more convenient, the stress generated in the welding assembly process can be released more effectively, and the crack or fracture of the tab in the welding assembly process is effectively avoided.

[0087] In one embodiment, the tabs of the same pole are stacked, and the through holes 30 are stacked to form an opening groove 40 opening to the outer edge of the winding core, and the groove bottom of the opening groove 40 is flush.

[0088] When the tabs of the same pole are stacked, the through holes 30 located at the folding position collectively form an opening groove 40 opening to the outer edge of the winding core, and the design of the flush groove bottom not only stabilizes the stacking state of the tabs in structure, but also ensures that the stress can be effectively released through the opening groove 40 in the subsequent welding assembly process, the integrity of the tab is maintained, the welding quality and the yield of battery manufacturing are improved, and the reliability of electrical connection is improved as a whole.

[0089] This design fully utilizes the stress release function of the through hole 30, and by forming the opening groove 40, a stress buffer zone is created while the tabs are stacked, which can effectively avoid material damage even under the influence of welding thermal stress, and maintain good contact and electrical performance between the tabs.

[0090] In one embodiment, the through hole 30 has a predetermined interval with the tab body 2, which reduces the difficulty of machining the through hole 30 on the tab, can effectively avoid damaging the structure of the tab body 2 in the process of machining the through hole 30, and improves the machining efficiency.

[0091] In one embodiment, the ratio of the size of the through hole 30 along the length direction of the tab body 2 to the size of the tab along the length direction of the tab body 2 is in the range of 1 / 4-1 / 2, which can avoid that the through hole 30 is too small to effectively release the stress, and can also avoid that the through hole 30 is too large to cause the connection size between the tab and the tab body 2 to be too small and the connection strength to be insufficient.

[0092] In one embodiment, along the direction from inside to outside of the winding core, the width of the tab along the winding direction increases.

[0093] Along the direction from inside to outside of the winding core, the width of the tab along the winding direction increases, which can effectively adapt to the natural deformation of the material in the winding process, ensure the stability and contact area of the tabs in each layer when stacked, and thus improve the welding quality and the reliability of electrical connection, while reducing the internal stress and preventing the tab from folding or warping in the subsequent assembly process, thereby ensuring high yield and excellent performance of battery manufacturing.

[0094] In one embodiment, the tabs of the same polarity are stacked and flush with each other on a side away from the outer edge of the winding core.

[0095] Stacking the tabs of the same polarity and keeping them flush with each other on a side away from the outer edge of the winding core ensures the orderliness and close contact of the tabs during stacking, which is conducive to the accurate implementation of the subsequent welding process and improves the quality and reliability of electrical connection. At the same time, the flush design reduces the space occupation inside the winding core, which helps to compact the overall structure and optimize the energy density of the battery.

[0096] In one embodiment, the tabs are rectangular or trapezoidal in projection along the stacking direction of the tab body 2. When the tabs are trapezoidal, the width of the tabs decreases along the direction away from the tab body 2.

[0097] The tabs are trapezoidal in projection along the stacking direction of the tab body 2, and the width decreases along the direction away from the tab body 2. This can effectively adapt to the material deformation during winding, reduce the probability of wrinkles and folding of the tabs during winding, and ensure the close fit and stable connection of the tabs during stacking. The geometric characteristics of the trapezoidal shape help to maximize the contact area of the tabs in a limited space, thereby improving the electrical conductivity. Moreover, the decrease in width along the direction away from the tab body helps to reduce the stress during tab welding assembly, prevent material damage, and ensure the electrical connection reliability and structural integrity during subsequent welding and assembly processes.

[0098] In one embodiment, the tabs include positive tabs 201 and negative tabs 101, and the positive tabs 201 and the negative tabs 101 are located at the same end of the body 1.

[0099] When the positive tabs 201 and the negative tabs 101 are located at the same end of the body 1, along the length direction of the tab body 2, the positive tabs 201 are located at the first side of the body 1, and the negative tabs 101 are located at the second side of the body 1. This structure can reduce the difficulty of forming the winding core and improve the forming and assembly efficiency.

[0100] In one embodiment, the positive tabs 201 and the negative tabs 101 are located at different ends of the body 1.

[0101] The positive tabs 201 and the negative tabs 101 are located at different ends of the body 1, including two cases. In one case, along the length direction of the tab body 2, the positive tabs 201 and the negative tabs 101 are located at the same side of the body 1, and along the width direction of the tab body 2, the positive tabs 201 and the negative tabs 101 are located at different ends of the body 1. In the other case, along the length direction of the tab body 2, the positive tabs 201 and the negative tabs 101 are located at different sides of the body 1, and along the width direction of the tab body 2, the positive tabs 201 and the negative tabs 101 are located at different ends of the body 1.

[0102] By the above manner, more forms of tab setting structures can be provided, more options are provided, the adaptability of the winding core is better, and different use requirements in different conditions can be adapted.

[0103] In one embodiment, the tabs are collected at the middle position of the stacking direction of the tab body 2.

[0104] The tabs are designed to be collected at the middle position of the stacking direction of the tab body 2, so that the tabs can be kept at the center of the thickness of the winding core throughout the winding process, effectively reducing the material stress concentration caused by the position deviation, and ensuring the stability and symmetry of the tabs in the subsequent welding process. By collecting the tabs at the middle position of the tab body 2, the double-winding core parallel assembly process can be simplified, and the complexity of the traditional A / B winding core pairing is avoided, and the production cost and process difficulty are reduced.

[0105] According to the embodiment of the present application, the preparation method of the winding core comprises: preparing a positive tab 20, a separator and a negative tab 10; stacking the positive tab 20, the separator and the negative tab 10 to form a to-be-wound structure; winding the to-be-wound structure, so that the positive tab 20 and the negative tab 10 are located at the winding position of the to-be-wound structure, and are folded with the winding of the to-be-wound structure.

[0106] The winding core preparation method of the present application precisely stacks the positive tab 20, the separator and the negative tab 10, and promotes the self-adaptive folding of the positive tab 201 and the negative tab 101 to a specific winding position during winding, realizes the ordered collection and positioning of the tabs in the winding core structure; the folding action of the tabs in this process combines the pre-designed tab shape, effectively disperses the winding stress, avoids the disordered warping or damage of the tabs, ensures the reliability of the subsequent welding process, improves the yield of battery manufacturing and the electrical performance stability of the final product.

[0107] In one embodiment, the step of preparing the positive tab 20, the separator and the negative tab 10 comprises: processing a through hole 30 at the root of the positive tab 201 of the positive tab 20, so that the through hole 30 extends along the length direction of the positive tab 20, and does not penetrate the two ends of the positive tab 201 along the length direction; processing a through hole 30 at the root of the negative tab 101 of the negative tab 10, so that the through hole 30 extends along the length direction of the negative tab 10, and does not penetrate the two ends of the negative tab 101 along the length direction.

[0108] By processing the through hole 30 at the root of the tab, the connection structure of the tab and the tab body 2 can be optimized, so that the through hole 30 is located at the folding position and forms an opening groove 40 with the opening facing the outside at the folding position after winding is completed. Not only is the state of the tab stacking structurally stable, but also the stress can be effectively released through the opening groove 40 during the subsequent welding assembly process, the integrity of the tab is maintained, and the welding quality and the yield of battery manufacturing are improved.

[0109] In one embodiment, the preparation method further includes: folding and fusing all the positive tabs 201 so that the positive tabs 201 are located at the center position in the thickness direction of the winding core; folding and fusing all the negative tabs 101 so that the negative tabs 101 are located at the center position in the thickness direction of the winding core.

[0110] In the preparation method of the application, by folding and fusing all the positive tabs 201 and the negative tabs 101 to the center position in the thickness direction of the winding core, the centralized management and optimized positioning of the tabs are realized. This dynamic process not only ensures the neat stacking of the tabs inside the winding core, avoids the problem of poor electrical contact caused by positional deviation during subsequent assembly and welding, but also reduces the waste of space inside the battery through symmetrical design, thereby improving the energy density. At the same time, the feature that the tabs are located at the center position simplifies the parallel assembly process of the double winding cores. During the parallel pairing of the double winding cores, only two identical winding cores need to be used to realize the pairing operation, without the need to manufacture A / B two different winding cores, thereby greatly reducing the manufacturing complexity.

[0111] For reference Figures 1 to 31 As shown in the drawings, according to the embodiment of the application, the tab is applied to the winding core or the preparation method of the winding core, which includes: a tab body 2, the tab body 2 has a coating area; an active material, coated on the coating area of the tab body 2; a tab, disposed on one side of the tab body 2 along the width direction of the tab body 2, the tab has a through hole 30 opened near one side of the tab body 2, and the through hole 30 does not penetrate the tab at both ends along the length direction of the tab body 2.

[0112] By opening the through hole 30 extending along the length direction of the tab at the root of the tab on one side of the tab body 2 and not penetrating the tab at both ends, in combination with the distribution of the active material in the coating area of the tab body 2, a unique structural design is formed. The through hole 30 as an optimized structure of the tab structure can effectively control the folding path and form of the tab, reduce the folding difficulty of the tab, and make it naturally fold in the center position in the thickness direction of the winding core. In the winding and battery assembly links, the through hole 30 plays a role in stress release, reduces the accumulation of internal stress caused by material deformation, and enhances the mechanical stability and electrical consistency of the battery.

[0113] In one embodiment, the through hole 30 has a preset interval with the tab body 2.

[0114] In one embodiment, the length of the through hole 30 increases and / or the length of the tab increases along the winding direction of the jelly-roll, starting from the beginning end.

[0115] In one embodiment, the tabs include positive tabs 201 and negative tabs 101, the dimension of the negative tab 101 along the length direction of the jelly-roll body 2 is Tf, the dimension of the positive tab 201 along the length direction of the jelly-roll body 2 is Tz, the interval between the positive tab 201 and the negative tab 101 in the same layer is S, the interval between two adjacent negative tabs 101 in different layers along the winding direction is 2S+Tz, and the interval between two adjacent positive tabs 201 in different layers along the winding direction is 2S+Tf.

[0116] The tab design in the embodiment ingeniously controls the interaction and positioning between the tabs in different layers during the winding process by setting the specific dimensions Tz and Tf of the positive tab 201 and the negative tab 101 along the length direction of the jelly-roll body 2 and the interval S therebetween; in particular, the interval 2S+Tz or 2S+Tf between the positive tab and the negative tab in different layers along the winding direction effectively avoids tab overlapping and interference, promotes the natural formation of the U-shaped folding, and ensures the stable folding of the tabs at the center of the jelly-roll thickness, thereby providing a good foundation for the subsequent welding process.

[0117] Tz and Tf can be the same or different.

[0118] In one embodiment, the tabs include positive tabs 201 and negative tabs 101, the dimension of the negative tab 101 along the length direction of the jelly-roll body 2 is Tf, the dimension of the positive tab 201 along the length direction of the jelly-roll body 2 is Tz, the interval between the positive tab 201 and the negative tab 101 in the same layer is S, and the interval between the positive tab 201 and the negative tab 101 in different layers along the winding direction is K, where K=n*(3S+Tf+Tz), and n is a positive integer.

[0119] When the number of tab layers of the jelly-roll is large, the difficulty of tab pre-welding and tab-to-tab welding is increased, and false welding and other adverse phenomena are prone to occur. Through the above design, the interval between the tabs in different layers can be controlled, the number of tab layers can be reduced, the difficulty of tab pre-welding and tab-to-tab welding can be reduced, the occurrence of false welding and other adverse phenomena can be reduced, and the welding quality can be improved.

[0120] According to an embodiment of the application, the battery cell includes a jelly-roll, which is the jelly-roll described above.

[0121] The electric core adopts the winding core as the core structure. Through the unique tab structure design and the optimized preparation process, the winding core effectively solves the problem of tab warping and folding in traditional winding cores, and realizes the precise folding of the positive and negative tabs at the center of the winding core thickness. This not only maintains the stable form of the tabs during the entire manufacturing and assembly process, ensuring the welding quality and the reliability of the electrical connection, but also simplifies the parallel assembly process of the double winding cores by reducing the demand for different types of winding cores, greatly improving the efficiency and cost-effectiveness of the electric core production, while ensuring the consistency and safety of the battery performance.

[0122] In one embodiment, the electric core includes at least two winding cores arranged in parallel.

[0123] Taking an electric core including two winding cores as an example, the two winding cores are the same structure and arranged side by side. According to the different positions of the tabs, the parallel structure of the two winding cores presents different connection forms.

[0124] In one embodiment, the positive tab 201 and the negative tab 101 of the winding core are located at the same end of the winding core, and the electric core further includes a positive connection sheet 50 and a negative connection sheet 60, wherein the positive connection sheet 5 is welded with the positive tab 201, and the negative connection sheet 60 is welded with the negative tab 101. In one embodiment, the welding method is ultrasonic welding. The welding method can also be other forms, such as laser welding.

[0125] When the positive connection sheet 5 and the positive tab 201 are welded, and the negative connection sheet 60 and the negative tab 101 are welded, the positive connection sheet 50 and the negative connection sheet 60 can be welded with the cover plate assembly 70 respectively. In one embodiment, the welding method is laser welding. The welding method can also be other forms, such as ultrasonic welding.

[0126] The cover plate assembly 70 is a plate structure, including a positive column and a negative column, and the cover plate assembly 70 is arranged at the end of the winding core where the tabs are arranged, and the positive column is welded with the positive connection sheet 50, and the negative column is welded with the negative connection sheet 60.

[0127] In one embodiment, the cover plate assembly 70 is provided with a positive support 701 and a negative support 702, and the positive support 701 is connected with the positive column, and the negative support 702 is connected with the negative column.

[0128] In one embodiment, the positive tab 201 is bent and welded on the positive support 701, and the negative tab 101 is bent and welded on the negative support 702. In one embodiment, the welding method is laser welding. The welding method can also be other forms, such as ultrasonic welding.

[0129] Embodiment one

[0130] For referenceFigures 1 to 13 FIG. 1 is a structural diagram of the first embodiment of the present invention.

[0131] In the first embodiment, the negative electrode sheet 10 consists of a negative electrode tab 101 and a negative electrode coating area, wherein the negative electrode active material is evenly coated on the upper and lower surfaces of the negative electrode coating area. The negative electrode tab 101 is an uncoated copper foil and is located on the same side of the negative electrode sheet 10. Viewed along the winding direction of the negative electrode sheet 10, the width Tf of the negative electrode tab 101 gradually increases from the starting end.

[0132] The positive electrode sheet 20 consists of a positive electrode tab 201 and a positive electrode coating area. The positive electrode active material is evenly coated on the upper and lower surfaces of the positive electrode coating area. The positive electrode tab 201 is an uncoated aluminum foil and is located on the same side of the positive electrode sheet 20. As viewed along the winding direction of the positive electrode sheet 20, the width Tz of the positive electrode tab 201 gradually increases from the starting end.

[0133] It is worth noting that Tf and Tz may be the same or different, and the present invention does not impose any specific limitation thereto.

[0134] A through hole 30 is provided in the inner region of each of the negative electrode tab 101 and the positive electrode tab 201 . The through hole 30 is close to the base of the tab. When viewed along the winding direction of the positive electrode sheet 20 , the length L of the through hole 30 gradually increases from the starting end.

[0135] It is worth noting that the lengths L of the through holes 30 may be the same or different, and the present invention does not impose any specific limitation thereto.

[0136] From the perspective of relative position, after the positive electrode sheet 20 and the negative electrode sheet 10 are stacked, the distance between adjacent negative electrode tabs 101 and positive electrode tabs 201 is S.

[0137] See also Figures 2 to 4 As shown, during the core forming process, Figure 1 The negative electrode sheet 10, positive electrode sheet 20, and separator shown are stacked in the order of separator-negative electrode sheet 10-separator-positive electrode sheet 20, and then wound in the order starting from the starting end to obtain a winding core. At this time, the negative electrode ear 101 and the positive electrode ear 201 are respectively located at the two ends of the same side of the winding core, and the corresponding single negative electrode ear 101 and positive electrode ear 201 are both U-folded, and the through hole 30 passes through the arc area of ​​the above-mentioned U-shaped fold to form an open groove 40.

[0138] See also Figure 5 and Figure 6 As shown, after the pole piece is wound, Figure 4 The negative electrode tab 101 and the positive electrode tab 201 are pre-welded to gather and fuse the layered tabs, for example, by ultrasonic welding. The gathered tabs are located at the center of the winding core in the thickness direction.

[0139] Referring to Figure 7 and Figure 8 shown, after the tab is gathered and welded, the positive tab 50 and the negative tab 60 are welded to the cover plate assembly, for example, by laser welding. Figure 5

[0140] Referring to Figures 9 to 13 shown, after the tab is gathered and welded, the positive tab 50 and the negative tab 60 are welded to the cover plate assembly, for example, by laser welding. Figure 8 Figure 11

[0141] Example Two

[0142] Referring to Figure 14 shown, this is a structure diagram of the second embodiment of the present application.

[0143] This embodiment is basically the same as the first embodiment, except that, in the first embodiment of the present application, each circle of the core corresponds to one negative tab 101 and one positive tab 201, which results in a larger number of layers of tabs of the core, as shown in Figure 1 which increases the difficulty of pre-welding of the tabs and welding of the tabs to the connecting pieces, and is prone to false welding and other adverse phenomena. Figure 3 In the second embodiment of the present application, every two circles of the core correspond to one negative tab 101 and one positive tab 201. In terms of relative position, the distance between the positive tab 201 and the adjacent negative tab 101 is S and K, respectively, where K = 3*S + Tf + Tz, and Tf and Tz correspond to the width of the negative tab 101 and the positive tab 201 at this position. Figure 14 Figure 1

[0144] Figure 7 In the second embodiment of the present application, the number of layers of the negative tab 101 and the positive tab 201 of the core is 50% of that of the first embodiment, as shown. Figure 3

[0145] It is worth noting that different distances can be set for the negative tab 101 and the positive tab 201 to obtain different numbers of layers of the tabs, and the present application is not limited in this regard.

[0146] Example Three

[0147] Referring to Figures 15 to 17 shown, this is a structure diagram of the third embodiment of the present application.

[0148] This embodiment is basically the same as the first embodiment, except that, in the first embodiment of the present application, the rectangular-shaped tabs are prone to wrinkling and folding risks during the winding of the core,​​​​​​Figure 15 The third embodiment sets the structure of the negative tab 101 and the positive tab 201 as trapezoids, and the obtained core tab is as shown in Figure 17 .

[0149] It is worth noting that the negative tab 101 and the positive tab 201 can also be set as different shapes respectively, and the present application is not limited specifically.

[0150] Embodiment Four

[0151] Referring to Figures 18 to 25 , a structure diagram of the fourth embodiment of the present application is shown.

[0152] Referring to Figure 18 and Figure 19 , the present embodiment is basically the same as the first embodiment, and the difference is that, in the present embodiment, the negative tab 101 and the positive tab 201 are located at the opposite sides of the body 1 of the core, that is, they are distributed at the two ends of the body 1 along the X direction, and from the Y direction, the negative tab 101 and the positive tab 201 are both located at the same side of the body 1. That is, along the width direction of the body 1, the negative tab 101 and the positive tab 201 are located at the two ends of the body 1, and along the length direction of the body 1, the negative tab 101 and the positive tab 201 are both located at the same side of the body 1.

[0153] Referring to Figure 20 and 21 , a state diagram of the parallel arrangement of the two cores in the present embodiment is shown, and on the basis of Figure 19 , the two cores after the pre-welding are placed side by side, and the negative tabs 101 of the two cores are opposite to each other, and the positive tabs 201 are opposite to each other.

[0154] Referring to Figure 22 and 23 , a structure diagram of the cover plate assembly 70 in the present embodiment is shown, and the cover plate assembly 70 is provided with the positive tab support 701 and the negative tab support 702, and the positive tab support 701 and the negative tab support 702 are connected with the positive column and the negative column respectively.

[0155] Referring to Figure 24 and 25 , a structure diagram of the tab and the cover plate support after the welding is shown, and on the basis of Figure 20 , the positive tab 201 is bent and welded on the positive tab support 701, and the negative tab 101 is bent and welded on the negative tab support 702, and the welding method adopts laser welding.

[0156] The difference from the first embodiment is that, in the first embodiment, the cover plate assembly is located at one end of the width direction of the body 1 of the core after the welding is completed, and in the present embodiment, the cover plate assembly is located at one end of the length direction of the body 1 of the core after the welding is completed.

[0157] Embodiment Five

[0158] Referring to Figures 26 to 31 Fig. 5 is a structural diagram of a fifth embodiment of the present application.

[0159] Figure 26 and 27 Fig. 5 is a structural diagram of a fifth embodiment of the present application. Figure 27 In the fifth embodiment, the negative tab 101 and the positive tab 201 are located at different sides (X direction distribution), and from the Y direction distribution, the negative tab 101 and the positive tab 201 are located at different ends. After pre-welding the negative tab 101 and the positive tab 201, the negative tab 101 and the positive tab 201 are respectively welded with the negative connecting piece 60 and the positive connecting piece 50, and the welding method is ultrasonic welding.

[0160] Figure 28 and 29 Fig. 5 is a structural diagram of a fifth embodiment of the present application. Figure 27 On the basis of Fig. 5, the wound core after welding is inserted into the shell 80, and the positive connecting piece 50 and the negative connecting piece 60 are respectively welded on the positive cover plate assembly and the negative cover plate assembly.

[0161] Figure 30 and 31 Fig. 5 is a structural diagram of a fifth embodiment of the present application. Figure 29 On the basis of Fig. 5, the positive cover plate assembly and the negative cover plate assembly are respectively welded with the port of the shell 80, and the welding method is laser welding.

[0162] According to the embodiment of the present application, the battery pack comprises the wound core or the battery cell.

[0163] It is to be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments consistent with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0164] It should be noted that the terms "first", "second", and so on as used in the specification and the claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily have to be used to describe a specific 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 application described herein can be implemented in an order other than that illustrated or described herein.

[0165] The above description is only the preferred embodiment of the present application, and is not intended to limit the present application. The present application can have various changes and modifications for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A winding core, characterized in that: The invention comprises a body (1), wherein the end of the body (1) is provided with a pole ear, and the body (1) comprises a wound pole piece body (2), wherein each pole ear is folded at the winding position of the pole piece body (2) as the pole piece body (2) is wound, and forms two segments (3) connected at the winding position of the pole piece body (2).

2. The winding core according to claim 1, characterized in that The pole lug is provided with a through hole (30) on a side close to the pole piece body (2); the through hole (30) is located at a folded position of the pole lug; the through hole (30) does not penetrate the pole lug along the folded direction of the pole lug.

3. The winding core according to claim 2, characterized in that Along the direction from the inside to the outside of the winding core, the width of the through hole (30) increases gradually.

4. The winding core according to claim 3, characterized in that The pole tabs of the same pole are stacked, and the through holes (30) are stacked to form an open groove (40) that opens to the outer edge of the winding core, and the bottoms of the open groove (40) are flush.

5. The winding core according to claim 2, characterized in that There is a preset interval between the through hole (30) and the pole piece body (2).

6. The winding core according to any one of claims 1 to 5, characterized in that Along the direction from the inside to the outside of the winding core, the width of the tab increases gradually along the winding direction.

7. The winding core according to claim 6, characterized in that The pole tabs of the same pole are stacked and flush with each other at a side away from an outer edge of the winding core.

8. The winding core according to any one of claims 1 to 5, characterized in that Projected along the stacking direction of the pole piece body (2), the pole lug is rectangular or trapezoidal. When the pole lug is trapezoidal, the width of the pole lug decreases in the direction away from the pole piece body (2).

9. The winding core according to any one of claims 1 to 5, characterized in that The electrode tabs include a positive electrode tab (201) and a negative electrode tab (101), wherein the positive electrode tab (201) and the negative electrode tab (101) are located at the same end of the body (1), or the positive electrode tab (201) and the negative electrode tab (101) are located at different ends of the body (1).

10. The winding core according to any one of claims 1 to 5, characterized in that The pole tabs are gathered at a middle position in the stacking direction of the pole piece body (2).

11. A method for preparing a winding core according to any one of claims 1 to 10, characterized in that: include: Prepare the positive electrode sheet (20), the separator and the negative electrode sheet (10); The positive electrode sheet (20), the separator and the negative electrode sheet (10) are stacked to form a structure to be wound; The structure to be wound is wound so that the positive electrode tab (201) of the positive electrode sheet (20) and the negative electrode tab (101) of the negative electrode sheet (10) are both located at the winding position of the structure to be wound and are folded as the structure to be wound is wound.

12. The preparation method according to claim 11, characterized in that The steps of preparing the positive electrode sheet (20), the separator and the negative electrode sheet (10) include: Processing a through hole (30) at the root of the positive electrode tab (201) of the positive electrode sheet (20) such that the through hole (30) extends along the length direction of the positive electrode sheet (20) and does not penetrate through both ends of the positive electrode tab (201) along the length direction; A through hole (30) is processed at the root of the negative electrode tab (101) of the negative electrode sheet (10), so that the through hole (30) extends along the length direction of the negative electrode sheet (10) and does not penetrate through both ends of the negative electrode tab (101) along the length direction.

13. The preparation method according to claim 11, characterized in that The preparation method further comprises: All the positive electrode tabs (201) are gathered and fused together so that the positive electrode tabs (201) are located at the center of the winding core in the thickness direction; All the negative electrode tabs (101) are gathered and fused together so that the negative electrode tabs (101) are located at the center of the winding core in the thickness direction.

14. A pole piece, applied to the winding core according to any one of claims 1 to 10, or the method for preparing the winding core according to any one of claims 11 to 13, characterized in that: include: A pole piece body (2), wherein the pole piece body (2) has a coating area; Active material, coated on the coating area of ​​the pole piece body (2); A pole ear is arranged on one side of the pole piece body (2) along the width direction of the pole piece body (2), a through hole (30) is provided on the side of the pole ear close to the pole piece body (2), and the through hole (30) does not pass through the pole ear at both ends along the length direction of the pole piece body (2).

15. The pole piece according to claim 14, characterized in that: There is a preset interval between the through hole (30) and the pole piece body (2).

16. The pole piece according to claim 14, characterized in that: Along the winding direction of the pole piece, starting from the starting end, the length of the through hole (30) increases gradually; and / or the length of the pole ear increases gradually.

17. The pole piece according to claim 14, characterized in that: The electrode sheet comprises a positive electrode sheet (20) and a negative electrode sheet (10); the electrode tab comprises a positive electrode tab (201) and a negative electrode tab (101); the positive electrode sheet (20) comprises the positive electrode tab (201); the negative electrode sheet (10) comprises the negative electrode tab (101); the dimension of the negative electrode tab (101) along the length direction of the electrode sheet body (2) is Tf; the dimension of the positive electrode tab (201) along the length direction of the electrode sheet body (2) is Tz; the spacing between the positive electrode tab (201) and the negative electrode tab (101) located in the same layer is S; the spacing between two negative electrode tabs (101) located in different layers and adjacent to each other in a winding direction is 2S+Tz; and the spacing between two positive electrode tabs (201) located in different layers and adjacent to each other in a winding direction is 2S+Tf.

18. The pole piece according to claim 14, characterized in that: The electrode sheet comprises a positive electrode sheet (20) and a negative electrode sheet (10); the electrode tab comprises a positive electrode tab (201) and a negative electrode tab (101); the positive electrode sheet (20) comprises the positive electrode tab (201); the negative electrode sheet (10) comprises the negative electrode tab (101); the electrode tab comprises a positive electrode tab (201) and a negative electrode tab (101); the dimension of the negative electrode tab (101) along the length direction of the electrode sheet body (2) is Tf; the dimension of the positive electrode tab (201) along the length direction of the electrode sheet body (2) is Tz; the spacing between the positive electrode tab (201) and the negative electrode tab (101) located in the same layer is S; the spacing between the positive electrode tab (201) and the negative electrode tab (101) located in different layers and adjacent to each other along the winding direction is K, wherein K=n*(3*S+Tf+Tz), and n is a positive integer.

19. A battery cell comprising a winding core, characterized in that: The winding core is the winding core according to any one of claims 1 to 10.

20. A battery pack, characterized in that: The invention comprises the winding core according to any one of claims 1 to 10 or the battery cell according to claim 19.

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