Winding core assembly and battery cell

Abstract

The utility model belongs to battery technical field discloses a kind of roll core assembly and battery monomer, roll core assembly includes roll core, roll core includes pole piece structure, pole piece structure includes pole piece and multiple tabs, pole piece is wound along winding direction, multiple tabs are set on pole piece along winding direction, along winding direction, the spacing between two adjacent tabs gradually increases, multiple tabs form at least two tab groups, all tab groups are evenly distributed along the circumference of roll core, the roll core assembly can improve the uniformity of roll core temperature distribution, and also can reduce the heat production when roll core charges and discharges.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to a winding assembly and a battery cell. Background Technology

[0002] During fast charging, cylindrical batteries exhibit uneven temperature distribution within the core, with significant temperature differences between high-temperature and low-temperature zones. This reduces the fast-charging performance of cylindrical batteries, shortens their cycle life, and increases the risk of thermal runaway.

[0003] Therefore, there is an urgent need to propose a core assembly and a battery cell to solve the above-mentioned technical problems. Utility Model Content

[0004] The first objective of this invention is to provide a core assembly that can improve the uniformity of core temperature distribution and reduce the heat generated during core charging and discharging.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] A core assembly includes a core, the core including an electrode structure, the electrode structure including an electrode and a plurality of tabs, the electrode being wound along a winding direction, the plurality of tabs being disposed on the electrode along the winding direction, the spacing between two adjacent tabs gradually increasing along the winding direction, the plurality of tabs forming at least two tab groups, and all tab groups being evenly distributed along the circumference of the core.

[0007] Optionally, the core also includes a diaphragm, and the number of electrode structures is two, with the two electrode structures having opposite polarities, and the diaphragm is sandwiched between the electrodes of the two electrode structures.

[0008] Optionally, the side of the electrode sheet facing away from the winding direction is designated as the winding start side, and the distance between the k-th electrode tab and the winding start side is P. k P k =2π×[r0×k+Δr×k×(k-1) / 2];

[0009] Where r0 is the radius of the winding needle used when winding the electrode sheet;

[0010] Δr=L p +L n +2L s , where L p and L n These represent the thicknesses of the two electrode structures, respectively.

[0011] L s The thickness of the diaphragm.

[0012] Optionally, the two electrode tabs are located on opposite sides of the winding core along the axial direction.

[0013] Optionally, the electrode includes an active material layer and a current collector, the active material layer covering the surface of the current collector, the current collector having a protrusion that protrudes from the active material layer along the axial direction of the core, and the protrusion forming an electrode tab.

[0014] Alternatively, the protrusion may be formed on the current collector using a cutting process.

[0015] Alternatively, the active material layer is formed on the current collector using a dry electrode process.

[0016] Optionally, the tabs in the same tab group overlap radially on the core, and the tabs in the same tab group are located on the same side of the core axis radially.

[0017] Optionally, the winding core assembly also includes conductive adapters, the number of which is the same as the number of tabs and corresponds one-to-one. Each conductive adapter is connected to a corresponding tab group, and the end of the conductive adapter facing away from the tab group is used to connect to the battery casing of the battery cell.

[0018] The second objective of this invention is to provide a battery cell in which the temperature distribution of the core is relatively uniform and the heat generation of the core is low during charging and discharging.

[0019] To achieve this objective, the present invention adopts the following technical solution:

[0020] A battery cell includes a battery casing and the aforementioned winding core assembly, the winding core assembly being disposed within the battery casing.

[0021] The beneficial effects of this utility model are:

[0022] First, the electrode sheet has multiple tabs along the winding direction, which divide the electrode sheet into multiple independent conductive regions. Electrons in each conductive region can flow into the tab corresponding to that conductive region, shortening the electron transport path in each conductive region and thus reducing the internal resistance of each conductive region. This not only helps to improve the uniformity of the core temperature distribution, but also reduces the heat generated during core charging and discharging.

[0023] Secondly, since the current density is higher in the area of ​​the core near the axis, the spacing between two adjacent tabs gradually increases along the winding direction of the electrode sheet, making the tabs in the area of ​​the core near the axis more dense. This further shortens the electron transmission path in the area near the core axis, thereby further reducing the internal resistance in the area near the core axis, making the temperature distribution of the core more uniform, and at the same time, further reducing the heat generated during the charging and discharging of the core.

[0024] Furthermore, multiple tabs form at least two tab groups, and all tab groups are evenly distributed along the circumference of the core to improve the uniformity of current density in the circumference of the core. This helps to distribute the heat generated by the core evenly in the circumference, thereby further improving the temperature uniformity of the core. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the core assembly provided in Embodiment 1 of this utility model;

[0026] Figure 2 This is a schematic diagram of the structure of the core provided in Embodiment 1 of this utility model;

[0027] Figure 3 This is a first structural schematic diagram of the electrode structure provided in Embodiment 1 of this utility model;

[0028] Figure 4 This is a schematic diagram of the second structure of the electrode structure provided in Embodiment 1 of this utility model;

[0029] Figure 5 This is a schematic diagram of the current collector structure provided in Embodiment 1 of this utility model;

[0030] Figure 6 This is a schematic diagram of the structure of the core provided in Embodiment 2 of this utility model;

[0031] Figure 7 This is a schematic diagram of the core assembly provided in Embodiment 2 of this utility model.

[0032] In the picture:

[0033] 100. Core; 110. Electrode structure; 111. Electrode; 1111. Winding start side; 1112. Active material layer; 1113. Current collector; 1113a. Coating area; 1113b. Uncoated area; 1113c. Cutting area; 1114. Protrusion; 112. Tab; 1121. Tab assembly; 120. Axis; 130. Non-tab area; 200. Conductive adapter. Detailed Implementation

[0034] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0035] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0036] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0037] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0038] Existing cylindrical battery cells often employ a single-tab structure, with the tab located near the axis of the winding core. Since current travels along the winding direction of the core, the single-tab structure prolongs the current path, increases the internal resistance of the core, and consequently increases the risk of thermal runaway. Furthermore, during charging and discharging, the current density is high in the region of the core near the axis. Although liquid cooling plates and other cooling devices are commonly used to cool the battery cells, these devices are located outside the battery casing, resulting in a significant distance between the core near the axis and the cooling device. This leads to poor heat dissipation in this area, causing a large temperature difference between this region and other areas, resulting in uneven temperature distribution within the core. This reduces the fast-charging performance of the battery cell, shortens its cycle life, and further increases the risk of thermal runaway.

[0039] Therefore, this utility model provides a winding core assembly and a battery cell to solve the above-mentioned technical problems.

[0040] Example 1

[0041] like Figures 1 to 3 As shown, the core assembly includes a core 100, which includes an electrode structure 110. The electrode structure 110 includes an electrode 111 and a plurality of electrode tabs 112. For example, the number of electrode tabs 112 can be twenty, twenty-five, or thirty, etc. The electrode 111 is wound along the winding direction, and the plurality of electrode tabs 112 are disposed on the electrode 111 along the winding direction. Along the winding direction, the spacing between two adjacent electrode tabs 112 gradually increases, and the plurality of electrode tabs 112 form at least two electrode tab groups 1121. All electrode tab groups 1121 are evenly distributed along the circumference of the core 100.

[0042] In this embodiment, the winding direction is Figure 3 In the x-direction, which is also the length direction of electrode 111, and the y-direction, which is the width direction of electrode 111, as shown... Figure 1 and Figure 3 As shown, the y-direction is also the axial direction of the core 100.

[0043] In this embodiment, the number of tab groups 1121 is three. Of course, in other embodiments, the number of tab groups 1121 can also be two, five or six, etc. The number of tab groups 1121 is preferably three to eight, so that the included angle between two adjacent tab groups 1121 is between 30° and 120°, and the density of tab groups 1121 in the circumferential direction of the core is moderate.

[0044] This embodiment provides a winding core assembly. The electrode sheet 111 is provided with a plurality of tabs 112 along the winding direction. The plurality of tabs 112 divide the electrode sheet 111 into a plurality of independent conductive regions. Electrons in each conductive region can be drawn into the tab 112 corresponding to that conductive region, shortening the electron transport path in each conductive region and thus reducing the internal resistance of each conductive region. This not only helps to improve the uniformity of temperature distribution of the winding core 100, but also reduces the heat generated during charging and discharging of the winding core 100.

[0045] On the other hand, since the current density is higher in the region of the core 100 near the axis 120, the spacing between two adjacent tabs 112 gradually increases along the winding direction of the electrode 111, making the tabs 112 in the region of the core 100 near the axis 120 more dense. This further shortens the electron transmission path in the region of the core 100 near the axis 120, thereby further reducing the internal resistance in the region of the core 100 near the axis 120, making the temperature distribution of the core 100 more uniform, and further reducing the heat generated during the charging and discharging of the core 100.

[0046] On the other hand, multiple tabs 112 form at least two tab groups 1121. All tab groups 1121 are evenly distributed along the circumference of the core 100 to improve the uniformity of current density in the circumference of the core 100. This helps to evenly distribute the heat generated by the core 100 in the circumference, further improving the temperature uniformity of the core 100. Furthermore, the even distribution of tab groups 1121 in the circumference of the core 100 ensures that the area between two adjacent tab groups 1121 is also evenly distributed in the circumference of the core 100. For ease of description, the area between two adjacent tab groups 1121 is referred to as the non-tab 112 region. Since the electrolyte migrates, refluxes, and wets the core 100 through the non-tab 112 region, the even distribution of the non-tab 112 region along the circumference of the core 100 helps to improve the uniformity of electrolyte distribution, thereby improving the migration, reflux, and wetting effects of the electrolyte. Secondly, when the explosion-proof valve of a single battery cell bursts, the high-temperature, high-pressure gas and substances inside the battery casing flow in the non-tab 112 area and are discharged from the battery casing through the explosion-proof valve. The non-tab 112 area is evenly distributed along the circumference of the core 100, which helps to ensure the uniform distribution of high-temperature, high-pressure gas and substances inside the battery casing. This not only makes the venting smoother and improves the venting efficiency, but also reduces the risk that the core 100 may move with the high-pressure gas inside the battery casing and eventually block the explosion-proof valve, thus improving the safety of the single battery cell.

[0047] Furthermore, the tabs 112 in the same tab group 1121 overlap radially in the core 100, and the tabs 112 in the same tab group 1121 are located on the same side of the axis 120 of the core 100 radially. Since the fixed end of the tab 112 is connected to the pole piece 111, and the free end of the tab 112 is connected to other tabs 112 in the same tab group 1121, the formation structure of the tab group 1121 in this embodiment can reduce the probability of the tab 112 breaking due to excessive bending near the fixed end, thereby reducing the probability of increased internal resistance of the core 100 due to the breakage of the tab 112.

[0048] It should be noted that in a single electrode group 1121, the number of electrodes 112 can be one, five, ten, or other numbers. In different electrode groups 1121, the number of electrodes 112 can be the same or different.

[0049] Optionally, the winding core assembly also includes conductive adapters 200. The number of conductive adapters 200 is the same as the number of tabs 1121 and they correspond one-to-one. Each conductive adapter 200 is connected to a corresponding tab 1121. The end of the conductive adapter 200 facing away from the tab 1121 is used to connect to the battery casing of the battery cell, so that the tab 1121 is electrically connected to the battery casing through the conductive adapter 200. This structure can ensure the reliability of the conductive connection between the tab 1121 and the battery casing, and avoid the problem of breakage of the tab 1121 or the connection position between the tab 1121 and the battery casing due to excessive spacing between the tab 1121 and the battery casing. This provides a guarantee for the reliability of the conductive connection between the tab 1121 and the battery casing, thereby reducing the probability of increased internal resistance of the winding core 100 due to connection failure between the tab 1121 and the battery casing. In this embodiment, the battery casing and the tab assembly 1121 are both welded and fixed to the conductive adapter 200 using processes such as laser welding. This structural design reduces the probability of incomplete soldering.

[0050] On the other hand, in this embodiment, all tab assemblies 1121 are evenly distributed along the circumference of the core 100, and the distribution of tab assemblies 1121 on the core 100 is relatively regular, thus avoiding the problem of missing connection between tab assemblies 1121 and conductive adapters 200. Furthermore, each tab assembly 1121 corresponds one-to-one with a conductive adapter 200, therefore all conductive adapters 200 are evenly distributed along the circumference of the core 100, and the distribution of conductive adapters 200 on the core 100 is relatively regular, thus avoiding the problem of missing connection between conductive adapters 200 and the battery casing. It is evident that this structural design provides further assurance for the reliability of the conductive connection between the tab assemblies 1121 and the battery casing, further reducing the probability of increased internal resistance of the core 100.

[0051] Furthermore, the conductive adapter 200 can be made of materials such as copper-nickel composite strip, which improves the welding yield of the conductive adapter 200 while also improving its conductivity. Of course, in other embodiments, the conductive adapter 200 can also be made of other conductive materials, which will not be listed here.

[0052] Optionally, the core 100 also includes a diaphragm. There are two electrode structures 110 with opposite polarities. The diaphragm is sandwiched between the electrodes 111 of the two electrode structures 110. Specifically, one of the two electrode structures 110 is a positive electrode structure, and the other is a negative electrode structure. The electrode 111 of the positive electrode structure is the positive electrode, the tab 112 of the positive electrode structure is the positive tab, and the tab group 1121 formed by the positive tab is the positive tab group. All positive tab groups are evenly distributed along the circumference of the core 100. The electrode 111 of the negative electrode structure is the negative electrode, the tab 112 of the negative electrode structure is the negative tab, and the tab group 1121 formed by the negative tab is the negative tab group. All negative tab groups are evenly distributed along the circumference of the core 100. The diaphragm is sandwiched between the positive and negative electrode sheets.

[0053] Furthermore, the positive and negative tabs are located on opposite sides of the winding core 100 along its axial direction, respectively, so that the positive tab group and the negative tab group are located on opposite sides of the winding core 100 along its axial direction. This structure can avoid mutual interference and accidental contact between the positive and negative tabs, and between the positive tab group and the negative tab group. In addition, it can also make the electrolyte distribution more uniform along the axial direction of the winding core 100, which is beneficial to improving the temperature uniformity of the winding core 100 along its axial direction.

[0054] Optionally, the side of electrode 111 facing away from the winding direction is designated as the winding start side 1111, and the distance between the k-th electrode tab 112 and the winding start side 1111 starting from the winding start side 1111 is P. k P k =2π×[r0×k+Δr×k×(k-1) / 2];

[0055] Where r0 is the radius of the winding needle used when winding the electrode 111 (i.e., the initial winding radius of the electrode 111);

[0056] Δr=L p +L n +2L s , where L p and L n The thicknesses of the electrodes 111 of the two electrode structures 110 are respectively.

[0057] L s The thickness of the diaphragm;

[0058] k is a positive integer greater than or equal to 1. For example, k can be 1, 2, 3 or other positive integers. When k = 1, P1 is the distance between the first tab 112 and the winding start side 1111. When k = 2, P2 is the distance between the second tab 112 and the winding start side 1111. The same applies when k is equal to other positive integers, which will not be elaborated here.

[0059] In this embodiment, L pL represents the thickness of the positive electrode. n The thickness of the negative electrode sheet is L; of course, in other implementations, it can also be L. p L represents the thickness of the negative electrode. n The thickness is the positive electrode plate.

[0060] When P k Satisfy P k When the formula =2π×[r0×k+Δr×k×(k-1) / 2] is used, the distance S between the k-th electrode 112 and the (k+1)-th electrode 112 can be made so that k Satisfying formula S k = 2π×[r0+(k-1)×Δr], where r0 is the radius of the winding needle used when winding electrode 111; Δr = L p +L n +2L s , where L p and L n The thicknesses L of the electrode 111 in the two electrode structures 110 are respectively. s Let S1 be the thickness of the diaphragm, and k be a positive integer greater than or equal to 1. For example, k can be 1, 2, 3, or other positive integers. When k = 1, S1 is the distance between the first tab 112 and the second tab 112. When k = 2, S2 is the distance between the second tab 112 and the third tab 112. The same applies when k equals other positive integers, which will not be elaborated here. It can be seen that the distance between two adjacent tabs 112 increases with the increase of k, and thus when P... k Satisfy P k When the formula =2π×[r0×k+Δr×k×(k-1) / 2] is used, the distance between two adjacent tabs 112 can be gradually increased along the winding direction of the electrode 111.

[0061] It should be noted that, since the tab 112 has a certain dimension in the winding direction (i.e., the x-direction), therefore, P k and S k The calculation reference position should be consistent. Figure 3 For example, the left side of the tab 112 is taken as the starting position of the tab 112, the right side of the tab 112 is taken as the ending position of the tab 112, and the middle part of the tab 112 in the x direction is taken as the middle position of the tab 112. In this embodiment, the starting position of each tab 112 is taken as the calculation reference position, that is, the distance between the starting position of the tab 112 and the winding starting side 1111 is P. k The distance between the starting positions of two adjacent tabs 112 is S. k Of course, in other embodiments, the termination position of the tab 112 can also be used as the calculation reference position, that is, the distance between the termination position of the tab 112 and the winding start side 1111 is P.k The distance between the termination positions of two adjacent tabs 112 is S. k Alternatively, the middle position of the tab 112 can be used as the calculation reference position, that is, the distance between the middle position of the tab 112 and the winding start side 1111 is P. k The distance between the middle positions of two adjacent tabs 112 is S. k Other examples of calculating the reference position will not be elaborated here, as long as P is made k and S k The calculation reference position should remain consistent.

[0062] On the other hand, when P k Satisfy P k When the formula is =2π×[r0×k+Δr×k×(k-1) / 2], several tabs 112 can overlap in the radial direction of the core 100, which makes it easier to gather and connect the tabs 112 located on the same side of the axis 120 of the core 100 in the radial direction of the core 100 to form a tab group 1121.

[0063] On the other hand, when P k Satisfy P k When the formula =2π×[r0×k+Δr×k×(k-1) / 2] is used, all tab groups 1121 can be evenly distributed along the circumference of the core 100.

[0064] Optionally, such as Figure 4As shown, the electrode 111 includes an active material layer 1112 and a current collector 1113. The active material layer 1112 covers the surface of the current collector 1113. The current collector 1113 has a protrusion 1114 that protrudes from the active material layer 1112 along the axial direction (i.e., the y-direction) of the core 100, forming an electrode tab 112. Specifically, the positive electrode includes a positive active material layer and a positive current collector. The positive active material layer covers the surface of the positive current collector. The positive current collector has a positive protrusion 1114 that protrudes from the positive active material layer along the axial direction of the core 100, forming a positive electrode tab. The negative electrode sheet includes a negative electrode active material layer and a negative electrode current collector. The negative electrode active material layer covers the surface of the negative electrode current collector. The negative electrode current collector has a negative electrode protrusion 1114, which protrudes from the negative electrode active material layer along the axial direction of the core 100, forming a negative electrode tab. Using the protrusion 1114 protruding from the current collector 1113 as a tab 112, so that the tab 112 has no active material layer 1112, can improve welding quality when welding tabs 112 in the same tab group 1121, or when welding tab group 1121 to conductive adapter 200. Furthermore, the absence of an active material layer 1112 on the tab 112 can reduce the weight of the core 100, which is beneficial for improving the energy density of the battery cell.

[0065] Furthermore, the protrusion 1114 is formed on the current collector 1113 using a cutting process. For example, laser slitting, die-cutting, or laser etching, all common cutting processes in the art, can be used to form the protrusion 1114 on the current collector 1113, thereby increasing the electrolyte permeation channels. Specifically, forming the protrusion 1114 on the current collector 1113 using a cutting process creates a cut surface at the cutting position of the current collector 1113. The cut surface forms additional electrolyte permeation channels, allowing the electrolyte to permeate into the current collector 1113 through the cut surface, thereby improving the electrolyte permeation efficiency and effect.

[0066] Secondly, the electrode 111 is provided with multiple tabs 112, that is, the current collector 1113 is provided with multiple protrusions 1114, which increases the number and distribution area of ​​the cut surface, and further improves the penetration efficiency and penetration effect of the electrolyte.

[0067] In this embodiment, the core 100 has a large-pore permeation channel formed on the cut surface of the current collector 1113, a mesopore permeation channel formed on the pores of the active material layer 1112, and a micropore permeation channel formed on the pores of the active material material itself in the active material layer 1112. The large-pore permeation channel, the mesopore permeation channel, and the micropore permeation channel form a multi-level pore network on the core 100. The electrolyte can gradually permeate through the multi-level pore network, which greatly improves the permeation efficiency and permeation effect of the electrolyte.

[0068] In actual production, either a dry electrode process or a wet electrode process can be used to prepare the active material layer 1112 on the current collector 1113. The dry electrode process is preferred because it allows for adjustment of the thickness of the active material layer 1112 before compaction, thereby adjusting the areal density of the electrode 111. It also allows for adjustment of the pressure applied during compaction of the active material layer 1112, thus adjusting the compaction density of the electrode 111. By adjusting the areal density and compaction density of the electrode 111, the size of the mesopore permeation channels can be adjusted, thereby regulating the electrolyte permeation efficiency and effect. Therefore, when the dry electrode process is used to prepare the active material layer 1112 on the current collector 1113, the controllability of the electrolyte permeation efficiency and effect can be achieved.

[0069] It should be noted that the above-mentioned dry electrode process and wet electrode process are both common production processes in this field, and the process itself will not be described in detail here.

[0070] The winding core assembly provided in this embodiment has multiple tabs 112 on the electrode sheet 111, and the spacing between two adjacent tabs 112 gradually increases along the winding direction. This effectively reduces the internal resistance of the winding core 100 to 1.5mΩ-2.5mΩ (lower than 80% of the internal resistance of traditional winding cores). During high-current charging, the winding core 100 generates low heat and has a relatively uniform temperature distribution. During fast charging, the temperature rise is ≤30℃, which can increase the charging rate to 4C (charging to 80% capacity in 10 minutes). Furthermore, while maintaining a capacity retention rate of ≥80%, the cycle life of the winding core 100 can be extended to 1500 cycles.

[0071] This embodiment also provides a method for preparing a core assembly, which can improve the uniformity of temperature distribution of the core 100 and reduce the heat generated during charging and discharging of the core 100.

[0072] Specifically, the method for manufacturing the core assembly includes the following steps:

[0073] S1. Prepare the positive electrode structure and the negative electrode structure. The method for preparing the positive electrode structure includes:

[0074] A positive current collector is provided, and a positive active material layer is prepared on the surface of the positive current collector to form a positive electrode sheet;

[0075] Multiple positive electrode tabs are prepared on the positive electrode sheet along the winding direction (i.e., the x-direction), such that the spacing between two adjacent positive electrode tabs gradually increases along the winding direction. For example, the number of positive electrode tabs can be twenty, twenty-five, or thirty, etc.

[0076] Methods for preparing negative electrode structures include:

[0077] A negative electrode current collector is provided, and a layer of negative electrode active material is prepared on the surface of the negative electrode current collector to form a negative electrode sheet;

[0078] Along the winding direction, multiple negative electrode tabs are prepared on the negative electrode sheet, such that the spacing between two adjacent negative electrode tabs gradually increases along the winding direction. For example, the number of negative electrode tabs can be twenty, twenty-five, or thirty, etc.

[0079] S2. Provide a separator, sandwich the separator between the positive electrode and the negative electrode, such that the side of the positive electrode structure facing the winding direction and the side of the negative electrode structure facing the winding direction are on the same side of the separator, so as to form a stacked structure.

[0080] The stacked structure is wound along the winding direction to form a core semi-finished product;

[0081] S3. Group several positive tabs in the positive electrode structure to form a positive tab group. Prepare at least two positive tab groups on the positive electrode structure so that all positive tab groups on the positive electrode structure are evenly distributed along the circumference of the core semi-finished product. For example, the number of positive tab groups can be two, three or five, etc., and the number of positive tabs in a single positive tab group can be five, ten or fifteen, etc.

[0082] Several negative electrode tabs in the negative electrode sheet structure are grouped together to form a negative electrode tab group. At least two negative electrode tab groups are prepared on the negative electrode sheet structure so that all negative electrode tab groups on the negative electrode sheet structure are evenly distributed along the circumference of the core semi-finished product. For example, the number of negative electrode tab groups can be two, three, or five, etc., and the number of negative electrode tabs in a single negative electrode tab group can be five, ten, or fifteen, etc.

[0083] The core assembly prepared by this method has multiple positive tabs on the positive electrode sheet along the winding direction and multiple negative tabs on the negative electrode sheet along the winding direction. Thus, both the positive and negative electrode sheets are divided into multiple independent conductive regions. Electrons in each conductive region can be drawn into the tab 112 corresponding to that conductive region, shortening the electron transport path in each conductive region and reducing the internal resistance of each conductive region. This not only helps to improve the uniformity of temperature distribution of the core 100, but also reduces the heat generated during charging and discharging of the core 100.

[0084] On the other hand, since the current density is high in the region of the core 100 near the axis 120, the spacing between two adjacent positive tabs and the spacing between two adjacent negative tabs gradually increase along the winding direction, making the tabs 112 in the region of the core 100 near the axis 120 more dense. This further shortens the electron transmission path in the region of the core 100 near the axis 120, thereby further reducing the internal resistance in the region of the core 100 near the axis 120, making the temperature distribution of the core 100 more uniform, and at the same time, further reducing the heat generated during the charging and discharging of the core 100.

[0085] On the other hand, multiple positive tabs form at least two positive tab groups, and all positive tab groups are evenly distributed along the circumference of the core 100. Similarly, multiple negative tabs form at least two negative tab groups, and all negative tab groups are evenly distributed along the circumference of the core 100. This improves the uniformity of current density along the circumference of the core 100, which helps to evenly distribute the heat generated by the core 100 along the circumference, further improving the temperature uniformity of the core 100. Furthermore, since both the positive and negative tab groups are evenly distributed along the circumference of the core 100, the area between two adjacent positive tab groups and the area between two adjacent negative tab groups are also evenly distributed along the circumference of the core 100. For ease of description, the areas between two adjacent positive tab groups and the areas between two adjacent negative tab groups are collectively referred to as the non-tab 112 region. Since the electrolyte migrates, refluxes, and wets the core 100 through the non-tab 112 area, the uniform distribution of the non-tab 112 area along the circumference of the core 100 helps improve the uniformity of electrolyte distribution, thereby enhancing the migration, reflux, and wetting effects of the electrolyte. Furthermore, when the explosion-proof valve of a battery cell bursts, the high-temperature, high-pressure gas and substances inside the battery casing flow through the non-tab 112 area and are discharged from the battery casing through the explosion-proof valve. The uniform distribution of the non-tab 112 area along the circumference of the core 100 facilitates the even distribution of high-temperature, high-pressure gas and substances inside the battery casing. This not only ensures smoother venting and improves venting efficiency but also reduces the risk of the core 100 moving with the high-pressure gas inside the battery casing and ultimately blocking the explosion-proof valve, thus improving the safety of the battery cell.

[0086] Optionally, the method for manufacturing the core assembly includes the following steps:

[0087] S4. Provide a positive electrode conductive adapter, and weld the end of each positive electrode tab away from the positive electrode plate to a corresponding positive electrode conductive adapter;

[0088] A negative electrode conductive adapter is provided, and the end of each negative electrode tab that is away from the negative electrode plate is soldered to a corresponding negative electrode conductive adapter.

[0089] The positive electrode conductive adapter and the negative electrode conductive adapter are used to weld to the cover and the casing of the battery case, respectively, so that the positive electrode tabs are electrically connected to the cover through the positive electrode conductive adapter, and the negative electrode tabs are electrically connected to the casing through the negative electrode conductive adapter.

[0090] Optionally, in step S1, a positive electrode active material layer is prepared on the surface of the positive electrode current collector using a dry electrode process, and a negative electrode active material layer is prepared on the surface of the negative electrode current collector. This allows control over the areal density and compaction density of the positive electrode sheet and the areal density and compaction density of the negative electrode sheet, thereby achieving control over the porosity of the positive electrode active material layer and the negative electrode active material layer, and realizing the adjustment of the electrolyte permeability of different battery cells.

[0091] Furthermore, a constant thickness compaction method is employed to compact the positive electrode active material layer on the positive electrode current collector and the negative electrode active material layer on the negative electrode current collector. This ensures that the thickness of the compacted positive electrode active material layer remains consistent in the winding direction, and the thickness of the compacted negative electrode active material layer remains consistent in the winding direction. This forms sheet-like positive and negative electrode sheets, avoiding radial deformation in the semi-finished core.

[0092] Optionally, in step S1, the method for preparing multiple positive electrodes includes:

[0093] Along the winding direction, multiple positive electrode cutting regions are set on the positive electrode sheet. For example, the number of positive electrode cutting regions can be five, ten, or fifteen, etc. Multiple positive electrode cutting regions are cut off from the positive electrode sheet, and the positive electrode sheet between two adjacent positive electrode cutting regions forms a positive electrode tab.

[0094] The method for preparing multiple negative electrodes is the same as the method for preparing multiple positive electrodes, and will not be repeated here.

[0095] This method allows for the formation of tabs 112 on the electrode sheet 111 through cutting. Compared to attaching each tab 112 individually to the electrode sheet 111, this method is simpler and more convenient, improving production efficiency and reducing production costs. Furthermore, forming tabs 112 on the electrode sheet 111 through cutting creates a cut surface at the cutting location of the current collector 1113. This cut surface forms additional electrolyte penetration channels, allowing electrolyte to penetrate into the current collector 1113 through the cut surface, thereby improving the electrolyte penetration efficiency and effect. Common cutting techniques in the field, such as laser slitting, die-cutting, or laser etching, can be used for cutting.

[0096] Furthermore, such as Figure 5As shown, in step S1, the method for preparing multiple positive tabs further includes: dividing the two sides of the positive current collector into a positive coating area and a positive uncoated area along the width direction (i.e., the y-direction); preparing a positive active material layer in the positive coating area; and setting multiple positive cutting areas in the positive uncoated area along the winding direction, with the width direction perpendicular to the winding direction. The multiple positive cutting areas on the positive current collector are cut off, and the portion between each two adjacent positive cutting areas forms a positive tab. The method for preparing multiple negative tabs is the same as the method for preparing multiple positive tabs, and will not be described again here. This method sets the cutting position in the uncoated area 1113b of the current collector 1113, ensuring that there is no active material layer 1112 on the tab 112. Therefore, when welding the gathered tabs 112, or when welding the tab assembly 1121 to the conductive adapter 200, the welding quality can be improved, and the overall weight of the winding core assembly can be reduced. In addition, the cutting area 1113c is located within the uncoated area 1113b, so the cutting area 1113c does not have an active material layer 1112, thus avoiding the waste of the active material layer 1112 and reducing production costs.

[0097] Optionally, in step S1, the method for preparing multiple positive electrodes includes:

[0098] The side of the positive electrode sheet facing away from the winding direction is designated as the positive electrode winding start side. The distance between the k-th positive electrode tab and the positive electrode winding start side, starting from the positive electrode winding start side, is set to P. k P k Satisfying the formula:

[0099] P k =2π×[r0×k+Δr×k×(k-1) / 2];

[0100] Where r0 is the radius of the winding needle used when winding the stacked structure (i.e., the initial winding radius);

[0101] Δr=L p +L n +2L s , where L p and L n The thicknesses of the electrodes 111 of the two electrode structures 110 are respectively.

[0102] L s The thickness of the diaphragm.

[0103] In this embodiment, L p L represents the thickness of the positive electrode. n The thickness is L, which represents the thickness of the negative electrode. Of course, in other implementations, it can also be L. p L represents the thickness of the negative electrode. n The thickness is the positive electrode plate.

[0104] The method for preparing multiple negative electrodes is the same as the method for preparing multiple positive electrodes, and will not be repeated here.

[0105] When P k Satisfy P k When the formula =2π×[r0×k+Δr×k×(k-1) / 2] is used, the distance S between the k-th positive electrode and the (k+1)-th positive electrode can be made so that k Satisfying formula S k = 2π×[r0+(k-1)×Δr]. It can be seen that the distance between two adjacent positive electrodes increases with increasing k, and further, when P... k Satisfy P k When using the formula =2π×[r0×k+Δr×k×(k-1) / 2], the distance between two adjacent positive electrodes can be gradually increased along the winding direction of electrode 111.

[0106] On the other hand, when P k Satisfy P k When the formula is =2π×[r0×k+Δr×k×(k-1) / 2], several positive electrode tabs can overlap in the radial direction of the semi-finished core, which makes it easier to gather and connect the positive electrode tabs located on the same side of the axis 120 of the semi-finished core in the radial direction of the semi-finished core to form a positive electrode tab group.

[0107] On the other hand, when P k Satisfy P k When the formula =2π×[r0×k+Δr×k×(k-1) / 2] is used, all positive electrode tabs can be evenly distributed along the circumference of the core semi-finished product.

[0108] Furthermore, in step S3, the method for preparing the positive electrode tab assembly includes: overlapping the core semi-finished product radially, and grouping the positive electrode tabs located on the same side of the core semi-finished product axis 120 radially to form a positive electrode tab assembly. This can reduce the probability of the positive electrode tab breaking due to excessive bending on the side closest to the positive electrode sheet.

[0109] The method for preparing the negative electrode ear assembly is the same as that for preparing the positive electrode ear assembly, and will not be repeated here.

[0110] In another embodiment, the method for preparing the positive electrode lug assembly includes: grouping together all the radially overlapping positive electrode lugs of the core semi-finished product to form a positive electrode lug assembly.

[0111] In another embodiment, the method for preparing the positive electrode tab assembly includes: setting several gathering areas along the circumference of the core semi-finished product, and gathering all the positive electrode tabs located in the same gathering area to form a positive electrode tab assembly.

[0112] This embodiment also provides a battery cell, which includes a battery casing and the aforementioned winding core assembly. The winding core assembly is disposed inside the battery casing, which is filled with electrolyte. When the battery cell uses the aforementioned winding core assembly, the temperature distribution of the winding core 100 is relatively uniform during charging and discharging, and the heat generation of the winding core 100 is low.

[0113] This embodiment also provides a battery cell, which includes a battery casing and a winding assembly prepared by the above-described winding assembly preparation method. The winding assembly is disposed inside the battery casing, which is filled with electrolyte. The winding assembly of this battery cell is made by the above-described winding assembly preparation method. During charging and discharging, the temperature distribution of the winding 100 is relatively uniform, and the heat generation of the winding 100 is low.

[0114] Example 2

[0115] This embodiment provides a core assembly. The differences between this embodiment and Embodiment 1 are mainly described below, while the similarities will not be repeated.

[0116] like Figure 6 and Figure 7 As shown, in this embodiment, there are six tab groups 1121, which are evenly distributed circumferentially along the core 100. The tabs 112 in the same tab group 1121 overlap radially on the core 100, and the tabs 112 in the same tab group 1121 are located on the same side of the axis 120 of the core 100 in the radial direction. In this embodiment, a tab group 1121 is provided on both sides of the axis 120 in the radial direction of the core 100, so as to... Figure 6 For example, the core 100 has two tab groups 1121 in the left and right directions. Compared with merging the two tab groups 1121 on the left and right sides into one tab group 1121, this structure, in the radial direction of the core 100, provides one tab group 1121 on each side of the axis 120. This can reduce the probability of the tab 112 breaking due to excessive bending in the area near the pole piece 111, and thus reduce the probability of the core 100's internal resistance increasing due to the breakage of the tab 112.

[0117] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make various obvious changes, readjustments, and substitutions without departing from the protection scope of this utility model. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A winding core assembly, characterized in that, The device includes a core (100), which includes an electrode structure (110). The electrode structure (110) includes an electrode (111) and a plurality of tabs (112). The electrode (111) is wound along a winding direction. The plurality of tabs (112) are disposed on the electrode (111) along the winding direction. Along the winding direction, the spacing between two adjacent tabs (112) gradually increases. The plurality of tabs (112) form at least two tab groups (1121). All tab groups (1121) are evenly distributed along the circumference of the core (100).

2. The core assembly according to claim 1, characterized in that, The core (100) also includes a diaphragm, and there are two electrode structures (110) with opposite polarities. The diaphragm is sandwiched between the electrodes (111) of the two electrode structures (110).

3. The core assembly according to claim 2, characterized in that, The side of the electrode (111) facing away from the winding direction is the winding start side (1111). Starting from the winding start side (1111), the distance between the kth electrode tab (112) and the winding start side (1111) is P. k P k =2π×[r0×k+Δr×k×(k-1) / 2]; Where r0 is the radius of the winding needle used when winding the electrode (111); Δr=L p +L n +2L s , where L p and L n The thicknesses of the electrodes (111) of the two electrode structures (110) are respectively. L s The thickness of the diaphragm.

4. The core assembly according to claim 2, characterized in that, The tabs (112) of the two electrode structures (110) are located on both sides of the winding core (100) along the axial direction.

5. The core assembly according to any one of claims 1-4, characterized in that, The electrode (111) includes an active material layer (1112) and a current collector (1113). The active material layer (1112) covers the surface of the current collector (1113). The current collector (1113) is provided with a protrusion (1114). The protrusion (1114) protrudes from the active material layer (1112) along the axial direction of the core (100). The protrusion (1114) forms the tab (112).

6. The core assembly according to claim 5, characterized in that, The protrusion (1114) is formed on the current collector (1113) by a cutting process.

7. The core assembly according to claim 5, characterized in that, The active material layer (1112) is formed on the current collector (1113) by a dry electrode process.

8. The core assembly according to any one of claims 1-4, characterized in that, The tabs (112) in the same tab group (1121) overlap radially on the core (100), and the tabs (112) in the same tab group (1121) are located on the same side of the axis (120) of the core (100) radially.

9. The core assembly according to any one of claims 1-4, characterized in that, The winding core assembly also includes conductive adapters (200), the number of which is the same as the number of tabs (1121) and corresponds one-to-one. Each conductive adapter (200) is connected to a corresponding tab group (1121), and the end of the conductive adapter (200) facing away from the tab group (1121) is used to connect to the battery casing of the battery cell.

10. A single battery cell, characterized in that, It includes a battery housing and a winding core assembly as described in any one of claims 1-9, the winding core assembly being disposed within the battery housing.

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