Method for manufacturing an electric cell and electric cell

Abstract

The application discloses a preparation method of an electric core and the electric core. Since an end face infiltration area is formed between a positive electrode tab area and a negative electrode tab area, compared with a mode of infiltrating through a winding center hole in the related art, the end face formed infiltration area can more conveniently infiltrate electrolyte from the side of the electric core to the electric core, so that the liquid injection efficiency of the electric core is improved.

Description

Technical Field

[0001] This application relates to the field of electronic technology, and in particular to a method for preparing a battery cell and the battery cell itself. Background Technology

[0002] In related technologies, batteries often inject electrolyte into the cell through the central hole on the electrode. However, it is difficult to ensure that the electrolyte fully penetrates the cell, resulting in low electrolyte injection efficiency. Summary of the Invention

[0003] This application provides a method for preparing a battery cell and a battery cell in general, so as to at least partially solve the above-mentioned technical problems.

[0004] To achieve the above objectives, according to a first aspect of this application, this application provides a method for manufacturing a battery cell, the battery cell comprising an electrode assembly, the electrode assembly comprising a positive electrode and a negative electrode, and comprising: Active materials are coated onto the electrode assembly using techniques such as extrusion coating, transfer coating, and gravure coating. The electrode assembly is then cut, and multiple positive and negative electrode tabs are cut from the blank foil at the edges of the positive and negative electrode sheets using an ultra-short pulse laser. The positive and negative electrode tabs are then chamfered and roughened on the surface. The electrode assembly is wound so that the positive electrode tab and the negative electrode tab form a positive electrode tab region and a negative electrode tab region at the same end of the battery cell, respectively. An end face wetting region is formed between the positive electrode tab region and the negative electrode tab region, and the end face wetting region radially isolates the positive electrode tab region and the negative electrode tab region along the end face of the battery cell.

[0005] In the cell manufacturing method of this application embodiment, since an end-face wetting area is formed between the positive electrode tab area and the negative electrode tab area, compared with the wetting method of winding the center hole in related technologies, the end-face wetting area can more conveniently wet the cell from the side of the cell with electrolyte, thereby improving the electrolyte injection efficiency of the cell.

[0006] It should also be noted that the wound positive electrode tab and multiple negative electrode tabs form the positive electrode tab area and negative electrode tab area at the same end of the cell, respectively. Therefore, it can reduce the extra space requirement inside the battery caused by the distribution of the tabs at both ends, so that the battery pack can be designed to be more compact.

[0007] In some embodiments, cutting the electrode assembly further includes: Cut out multiple positive electrode tabs and / or multiple negative electrode tabs; and / or, The winding of the electrode assembly further includes: Along the width direction of the positive electrode tab, a plurality of the positive electrode tabs overlap; and / or, along the width direction of the negative electrode tab, a plurality of the negative electrode tabs overlap.

[0008] Thus, the positive electrode tabs overlap in the width direction, forming a smaller positive electrode tab area on the end face of the cell. Under the same conditions, this allows for a larger wetting area on the end face, facilitating electrolyte wetting and ensuring injection efficiency. Similarly, the negative electrode tabs overlap in the width direction, forming a smaller negative electrode tab area on the end face of the cell. Under the same conditions, this allows for a larger wetting area on the end face, facilitating electrolyte wetting and ensuring injection efficiency.

[0009] Furthermore, since the positive and negative electrode tab regions occupy a relatively small proportion on the end face of the cell, the electrolyte can more evenly wet the cell, thereby improving the energy density of the cell.

[0010] In some embodiments, cutting the electrode assembly further includes: Multiple positive electrode tabs are cut out, wherein the widths of the multiple positive electrode tabs are the same, and the distances between adjacent positive electrode tabs are unequal; and / or, Multiple negative electrode tabs are cut out, wherein the widths of the multiple negative electrode tabs are the same, and the distances between two adjacent negative electrode tabs are unequal.

[0011] Understandably, as the thickness of the battery cell increases continuously during winding, in this embodiment, the distance between two adjacent positive electrode tabs gradually increases, so that the positive electrode tabs can overlap in the radial direction of the end face of the battery cell during winding to form a small positive electrode tab area; similarly, the distance between two adjacent negative electrode tabs gradually increases, so that the negative electrode tabs can overlap in the radial direction of the end face of the battery cell during winding to form a small negative electrode tab area.

[0012] In some embodiments, cutting the electrode assembly includes: Determine the starting point of the winding of the electrode assembly; The starting position of the first positive electrode tab on the positive electrode sheet is set based on the winding start point, and the starting position of the first negative electrode tab on the negative electrode sheet is determined; wherein, the positive electrode tab area and the negative electrode tab area are spaced apart at a preset angle α, the distance between the first positive electrode tab and the first negative electrode tab is α / 360 of the circumference of the first turn of the electrode assembly after winding, and the distance between the first positive electrode tab and the first negative electrode tab is the distance between the center line of the first positive electrode tab and the center line of the first negative electrode tab; The first positive electrode tab on the positive electrode sheet and the first negative electrode tab on the negative electrode sheet are cut out according to the determined position.

[0013] In some embodiments, the positive electrode tab region and the negative electrode tab region are arranged at a 180° interval, and the distance between the first positive electrode tab and the first negative electrode tab is half the circumference of the first turn of the electrode assembly after winding.

[0014] Thus, once the winding start point is defined, the positions of the first positive electrode tab and the first negative electrode tab are set according to the winding start point. It is only necessary to ensure that the distance between the first positive electrode tab and the first negative electrode tab is half the circumference of the first turn of the cell, so that the first positive electrode tab and the first negative electrode tab are symmetrically set after the cell is wound.

[0015] Understandably, in the specific manufacturing process, the starting position of the first positive electrode tab can be set first based on the starting point of winding, and then the starting position of the first negative electrode tab can be determined based on the starting position of the first positive electrode tab; alternatively, the starting position of the first negative electrode tab can be set first based on the starting point of winding, and then the starting position of the first positive electrode tab can be determined based on the starting position of the first negative electrode tab.

[0016] In some embodiments, the electrode assembly further includes a separator located between the positive electrode and the negative electrode, and the cutting of the electrode assembly further includes: Calculate the circumference L of each turn of the battery cell after winding. n L n =πD n D n =T core +2n(T) anode +T cathode +2T sep ); Among them, D n T is the diameter of the nth turn of the battery cell; core T is the diameter of the first coil of the battery cell; anode T represents the thickness of the negative electrode sheet. cathode T is the thickness of the positive electrode sheet. sep The thickness of the diaphragm; A first spacing is formed between every two adjacent positive electrode tabs, and each of these first spacings E is determined sequentially. n And cut out multiple positive electrode tabs according to multiple first spacings, wherein E n =L n ; and / or, A second spacing is formed between every two adjacent negative electrode tabs, and each second spacing F is determined sequentially.n And cut out multiple negative electrode tabs according to multiple second spacings, wherein F n =L n .

[0017] It should also be noted that the thickness of the positive electrode includes the thickness of the coating and the thickness of the foil; similarly, the thickness of the negative electrode also includes the thickness of the coating and the thickness of the foil.

[0018] Furthermore, in the actual manufacturing process, the position of each positive electrode tab can be calculated first, and then the positive electrode tab can be cut; similarly, the position of each negative electrode tab can be calculated first, and then the negative electrode tab can be cut.

[0019] Understandably, after the battery cell is wound, it can be viewed as a spiral that continuously thickens. Therefore, the circumference of the nth turn is calculated based on the diameter of the nth turn, and the size of the nth first spacing is set as the circumference of the nth turn. The size of the nth second spacing is also set as the circumference of the nth turn. This ensures that each positive electrode tab is perfectly stacked after winding, and each negative electrode tab is also perfectly stacked. All positive and negative electrode tabs form two distinct and closely arranged tab regions on the same end of the battery. This makes the non-tab region larger than the tab region, and the non-tab region can form an electrolyte wetting channel, which facilitates the electrolyte wetting of the battery cell.

[0020] In some embodiments, cutting the electrode assembly further includes: correcting the circumference L of each turn of the battery cell according to an empirical coefficient, L n =G*πD n Where G is an empirical coefficient, and G is greater than or equal to 0.98 and less than or equal to 1.02.

[0021] Understandably, in actual production, the positive and negative electrode materials will be stretched and compressed, and there will also be tension changes and slippage during the winding process of the battery cell. Therefore, the theoretical value needs to be multiplied by an empirical coefficient for fine-tuning to correct the error and better ensure that each positive electrode tab is perfectly stacked after winding, and each negative electrode tab is also perfectly stacked.

[0022] Secondly, this application also provides a battery cell, the battery cell including a positive electrode sheet and a negative electrode sheet wound together, the positive electrode sheet including a positive electrode tab, the negative electrode sheet including a negative electrode tab, the positive electrode tab and the negative electrode tab respectively forming a positive electrode tab region and a negative electrode tab region at the same end of the battery cell, an end face wetting region forming between the positive electrode tab region and the negative electrode tab region, the end face wetting region radially isolating the positive electrode tab region and the negative electrode tab region along the end face of the battery cell.

[0023] In the battery cell of this application embodiment, since an end-face wetting area is formed between the positive electrode tab area and the negative electrode tab area, compared with the method of wetting by winding the center hole in related technologies, the end-face wetting area can more conveniently wet the battery cell from the side of the battery cell, thereby improving the electrolyte injection efficiency of the battery cell.

[0024] In some embodiments, the positive electrode sheet includes a plurality of the positive electrode tabs; and / or, the negative electrode sheet includes a plurality of the negative electrode tabs.

[0025] This allows the electrode to be connected to other devices through multiple tabs, ensuring a good connection.

[0026] In some embodiments, a plurality of positive electrode tabs overlap along the width direction of the positive electrode tab; and / or, a plurality of negative electrode tabs overlap along the width direction of the negative electrode tab.

[0027] Thus, the positive electrode tabs overlap in the width direction, forming a smaller positive electrode tab area on the end face of the cell. Under the same conditions, this allows for a larger wetting area on the end face, facilitating electrolyte wetting and ensuring injection efficiency. Similarly, the negative electrode tabs overlap in the width direction, forming a smaller negative electrode tab area on the end face of the cell. Under the same conditions, this allows for a larger wetting area on the end face, facilitating electrolyte wetting and ensuring injection efficiency.

[0028] Furthermore, since the positive and negative electrode tab regions occupy a relatively small proportion on the end face of the cell, the electrolyte can more evenly wet the cell, thereby improving the energy density of the cell.

[0029] In some embodiments, the widths of the plurality of positive electrode tabs are the same, but the distances between two adjacent positive electrode tabs are unequal; and / or, the widths of the plurality of negative electrode tabs are the same, but the distances between two adjacent negative electrode tabs are unequal.

[0030] Understandably, as the thickness of the battery cell increases continuously during winding, in this embodiment, the distance between two adjacent positive electrode tabs gradually increases, so that the positive electrode tabs can overlap in the radial direction of the end face of the battery cell during winding to form a small positive electrode tab area; similarly, the distance between two adjacent negative electrode tabs gradually increases, so that the negative electrode tabs can overlap in the radial direction of the end face of the battery cell during winding to form a small negative electrode tab area.

[0031] In some embodiments, the positive electrode tab region and the negative electrode tab region are arranged symmetrically.

[0032] This ensures that the two non-tab regions formed between the positive and negative electrode tab regions are of uniform size, thereby ensuring uniform electrolyte penetration, improving current distribution uniformity, and extending battery cycle life.

[0033] In some embodiments, the heights of the plurality of positive electrode tabs are unequal; and / or, the heights of the plurality of negative electrode tabs are unequal.

[0034] In this way, compared to the uniform height of the positive electrode tabs and the uniform height of the negative electrode tabs in related technologies, setting the heights of multiple positive electrode tabs to be unequal and the heights of multiple negative electrode tabs to be unequal can avoid the problem that the electrode completely wraps around the end face of the core after winding, and also avoids the problem that the tabs are too tightly attached to each other after being flattened, making it difficult for the electrolyte to penetrate from the side, resulting in low electrolyte injection efficiency, poor electrolyte retention coefficient, and affecting battery cycle life.

[0035] In some embodiments, a plurality of positive electrode tabs are arranged in a stepped manner along the direction of the diameter of the battery cell; and / or, a plurality of negative electrode tabs are arranged in a stepped manner along the direction of the diameter of the battery cell.

[0036] It is understood that in this embodiment, since the heights of the multiple positive electrode tabs are not equal, the multiple positive electrode tabs will overlap in stages, thus forming a stepped overlap surface; similarly, since the heights of the multiple negative electrode tabs are not equal, the multiple negative electrode tabs will overlap in stages, thus forming a stepped overlap surface.

[0037] This prevents the tabs from sticking too tightly together after being flattened, allowing the electrolyte to seep in from the sides and improving the electrolyte injection efficiency of the battery cell.

[0038] Thus, the stepped tab design makes the current distribution inside the cell more uniform, which can better disperse the current and avoid the current from concentrating at a certain point, thereby reducing local overheating and uneven aging of electrode materials.

[0039] In this embodiment, the height of the plurality of positive electrode tabs gradually decreases along the direction from the inner layer to the outer layer of the battery cell; and / or, the height of the plurality of negative electrode tabs gradually decreases along the direction from the inner layer to the outer layer of the battery cell.

[0040] However, this design is not limited to this. In other embodiments, the height of the plurality of positive electrode tabs may gradually increase along the direction from the inner layer to the outer layer of the battery cell, or the height of the plurality of negative electrode tabs may gradually increase.

[0041] In some embodiments, the ratio of the tallest positive electrode tab to the shortest positive electrode tab is greater than 1 and less than or equal to 2; and / or, the ratio of the tallest negative electrode tab to the shortest negative electrode tab is greater than 1 and less than or equal to 2.

[0042] In this way, the ratio of the tallest positive electrode tab to the shortest positive electrode tab is between 1 and 2, and the ratio of the tallest negative electrode tab to the shortest negative electrode tab is between 1 and 2. This ensures that the current distribution is uniform and that the structural strength is not affected by excessive differences in electrode height.

[0043] Thus, the battery cell manufactured by the battery cell manufacturing method in this application, under the same conditions, can reduce the internal resistance of the battery cell by more than 35%, improve the rate performance by 40%, improve the current distribution uniformity by 50%, extend the cycle life by 30%, improve the material and space utilization, increase the energy density by 6%, improve the thermal distribution uniformity of the battery cell by 60%, reduce the risk of thermal runaway, improve the reliability of the tab connection, and reduce the failure rate by 50%.

[0044] In the cell manufacturing method of this application embodiment, since an end-face wetting area is formed between the positive electrode tab area and the negative electrode tab area, compared with the wetting method of winding the center hole in related technologies, the end-face wetting area can more conveniently wet the cell from the side of the cell with electrolyte, thereby improving the electrolyte injection efficiency of the cell.

[0045] In the battery cell of this application embodiment, since an end-face wetting area is formed between the positive electrode tab area and the negative electrode tab area, compared with the method of wetting by winding the center hole in related technologies, the end-face wetting area can more conveniently wet the battery cell from the side of the battery cell, thereby improving the electrolyte injection efficiency of the battery cell. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] To gain a more complete understanding of this application and its beneficial effects, the following description will be provided in conjunction with the accompanying drawings, wherein the same reference numerals in the following description denote the same parts.

[0048] Figure 1 This is a flowchart of a method for manufacturing a battery cell provided in an exemplary embodiment of this disclosure; Figure 2 This is a schematic diagram of the structure of the battery cell provided in an exemplary embodiment of this disclosure; Figure 3 This is a schematic diagram of the first structure of the positive electrode sheet provided in an exemplary embodiment of this disclosure; Figure 4This is a schematic diagram of the first structure of the negative electrode sheet provided in an exemplary embodiment of this disclosure; Figure 5 This is a schematic diagram of the second structure of the positive electrode sheet provided in an exemplary embodiment of this disclosure; Figure 6 This is a schematic diagram of the second structure of the negative electrode sheet provided in an exemplary embodiment of this disclosure.

[0049] Explanation of reference numerals in the attached figures: 1. Positive electrode plate; 11 positive electrode tabs; 2. Negative electrode plate; 21. Negative electrode tab; 3. Battery cell; 31. Positive electrode tab area; 32. Negative electrode tab area; 33. Non-tab area; 34. Center hole. Detailed Implementation

[0050] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the protection scope of this application.

[0051] In related technologies, the preparation of electrodes for large cylindrical batteries with opposite output terminals mainly suffers from the following technical defects: (1) Unreasonable tab design: Traditional tabs adopt a full tab equal height design, which results in the tab stack completely covering the end face of the core after winding. In addition, after the full tab is flattened, the tabs are too tightly attached, making it difficult for the electrolyte to penetrate from the side. It mainly relies on the winding center hole 34, resulting in low liquid injection efficiency and poor liquid retention coefficient, which affects the battery cycle life.

[0052] (2) Limited energy density: The design of the tabs at both ends requires space to be reserved for the tabs to be led out and connected, which reduces the height of the electrode and the utilization rate of the internal space of the battery. Secondly, some tabs do not play a real conductive role, increasing the weight, thus limiting the energy density of the battery.

[0053] (3) Safety issues: The design with tabs at both ends may cause the tabs to insert into the core during manufacturing, increasing the risk of thermal runaway. Although it is a full tab structure, the welding contact surface with the current collector is limited, and there are problems with incomplete welding, which leads to excessive heat generation and increases the risk of thermal runaway.

[0054] This application provides a method for manufacturing a battery cell 3. Please refer to [link / reference]. Figure 1 , Figure 1 A flowchart illustrating the manufacturing method of the battery cell 3 provided in this embodiment.

[0055] A method for manufacturing a battery cell 3, the battery cell 3 comprising an electrode assembly, the electrode assembly comprising a positive electrode 1 and a negative electrode 2, the method for manufacturing the battery cell 3 comprising: Active materials are coated onto the electrode assembly using technologies such as extrusion coating, transfer coating, and gravure coating. The electrode assembly is then cut, and multiple positive electrode tabs 11 and multiple negative electrode tabs 21 are cut from the blank foil at the edges of the positive electrode 1 and negative electrode 2 using an ultra-short pulse laser. The positive electrode tabs 11 and negative electrode tabs 21 are then chamfered and roughened on the surface. The electrode assembly is wound so that the positive electrode tab 11 and the negative electrode tab 21 form a positive electrode tab region 31 and a negative electrode tab region 32 at the same end of the cell 3, respectively. An end face wetting region is formed between the positive electrode tab region 31 and the negative electrode tab region 32. The end face wetting region radially isolates the positive electrode tab region 31 and the negative electrode tab region 32 along the end face of the cell.

[0056] In the manufacturing method of the battery cell 3 in this application embodiment, since an end face wetting area is formed between the positive electrode tab area 31 and the negative electrode tab area 32, compared with the method of wetting by winding the center hole in related technologies, the end face wetting area can more conveniently wet the battery cell 3 from the side of the battery cell 3, thereby improving the liquid injection efficiency of the battery cell 3.

[0057] It should also be noted that the wound positive electrode tab 11 and multiple negative electrode tabs 21 form a positive electrode tab region 31 and a negative electrode tab region 32 at the same end of the cell 3, respectively. Therefore, the additional space requirement inside the battery caused by the tabs being distributed at both ends can be reduced, allowing the battery pack to be designed to be more compact.

[0058] In some embodiments, cutting the electrode assembly further includes: Cut out multiple positive electrode tabs 11 and / or multiple negative electrode tabs 21; and / or, Winding the electrode assembly also includes: Along the width direction of the positive electrode tab 11, multiple positive electrode tabs 11 overlap; and / or, along the width direction of the negative electrode tab 21, multiple negative electrode tabs 21 overlap.

[0059] Thus, the positive electrode tabs 11 overlap in the width direction, forming a smaller positive electrode tab area 31 on the end face of the cell 3. Under the same conditions, this allows for a larger end face wetting area, facilitating electrolyte wetting and ensuring injection efficiency. Similarly, the negative electrode tabs 21 overlap in the width direction, forming a smaller negative electrode tab area 32 on the end face of the cell 3. Under the same conditions, this allows for a larger end face wetting area, facilitating electrolyte wetting and ensuring injection efficiency.

[0060] Furthermore, since the positive electrode tab region 31 and the negative electrode tab region 32 occupy a small proportion on the end face of the cell 3, the electrolyte can more evenly wet the cell 3, thereby improving the energy density of the cell.

[0061] In some embodiments, cutting the electrode assembly further includes: Multiple positive electrode tabs 11 are cut out, wherein the widths of the multiple positive electrode tabs 11 are the same, the distances between adjacent positive electrode tabs 11 are unequal, and / or, Multiple negative electrode tabs 21 are cut out, wherein the width of the multiple negative electrode tabs 21 is the same, and the distance between two adjacent negative electrode tabs 21 is not equal.

[0062] Understandably, as the thickness of the battery cell 3 increases continuously during winding, in this embodiment, the distance between two adjacent positive electrode tabs 11 gradually increases, so that the positive electrode tabs 11 can overlap in the radial direction of the end face of the battery cell 3 during winding to form a small positive electrode tab region 31; similarly, the distance between two adjacent negative electrode tabs 21 gradually increases, so that the negative electrode tabs 21 can overlap in the radial direction of the end face of the battery cell 3 during winding to form a small negative electrode tab region 32.

[0063] In some embodiments, cutting the electrode assembly includes: Determine the starting point of the electrode assembly winding; The starting position of the first positive electrode tab 11 on the positive electrode plate 1 is set based on the starting point of winding, and the starting position of the first negative electrode tab 21 on the negative electrode plate 2 is determined; wherein, the positive electrode tab area 31 and the negative electrode tab area 32 are set at a preset angle α, the distance between the first positive electrode tab 11 and the first negative electrode tab 21 is α / 360 of the circumference of the first turn after the cell 3 is wound, and the distance between the first positive electrode tab 11 and the first negative electrode tab 21 is the distance between the center line of the first positive electrode tab 11 and the center line of the first negative electrode tab 21; The first positive electrode tab 11 on the positive electrode plate 1 and the first negative electrode tab 21 on the negative electrode plate 2 are cut out according to the determined position.

[0064] In some embodiments, the positive electrode tab region 31 and the negative electrode tab region 32 are arranged at a 180° interval, and the distance between the first positive electrode tab 11 and the first negative electrode tab 21 is half the circumference of the first turn of the electrode assembly after winding.

[0065] Thus, once the winding start point is defined, the positions of the first positive electrode tab 11 and the first negative electrode tab 21 are set according to the winding start point. It is only necessary to ensure that the distance between the first positive electrode tab 11 and the first negative electrode tab 21 is half the circumference of the first turn of the battery cell 3, so that the first positive electrode tab 11 and the first negative electrode tab 21 are symmetrically set after the battery cell 3 is wound.

[0066] Understandably, in the specific manufacturing process, the starting position of the first positive electrode tab 11 can be set first based on the starting point of winding, and then the starting position of the first negative electrode tab 21 can be determined based on the starting position of the first positive electrode tab 11; alternatively, the starting position of the first negative electrode tab 21 can be set first based on the starting point of winding, and then the starting position of the first positive electrode tab 11 can be determined based on the starting position of the first negative electrode tab 21.

[0067] In some embodiments, the electrode assembly further includes a separator located between the positive electrode 1 and the negative electrode 2, and cutting the electrode assembly further includes: Calculate the circumference L of each turn of the wound cell 3 sequentially. n L n =πD n D n =T core +2n(T) anode +T cathode +2T sep ); Among them, D n T is the diameter of the nth turn of cell 3; core T is the diameter of the first coil of cell 3; anode The thickness of negative electrode plate 2; T cathode T represents the thickness of the positive electrode 1. sep The thickness of the diaphragm; Reference Figure 3 As shown, a first spacing is formed between every two adjacent positive electrode tabs 11, and each first spacing E is determined sequentially. n And cut out multiple positive electrode tabs 11 according to multiple first spacings, wherein E n =L n ; and / or, Reference Figure 4 As shown, a second spacing is formed between every two adjacent negative electrode tabs 21, and each second spacing F is determined sequentially. n And multiple negative electrode tabs 21 are cut according to multiple second spacings, wherein F n =L n .

[0068] It should also be noted that the thickness of the positive electrode 1 includes the thickness of the coating and the thickness of the foil; similarly, the thickness of the negative electrode 2 also includes the thickness of the coating and the thickness of the foil.

[0069] Furthermore, in the specific manufacturing process, the position of each positive electrode tab 11 can be calculated first, and then the positive electrode tab 11 can be cut; similarly, the position of each negative electrode tab 21 can be calculated first, and then the negative electrode tab 21 can be cut.

[0070] It is understandable that after the cell 3 is wound, the cell 3 can be regarded as a spiral that is continuously thickening. Therefore, the circumference of the nth turn is calculated based on the diameter of the nth turn of the cell 3, and the size of the nth first spacing is set as the circumference of the nth turn of the cell 3. The size of the nth second spacing is set as the circumference of the nth turn of the cell 3. This ensures that each positive electrode tab 11 and each negative electrode tab 21 are perfectly stacked after winding. All positive electrode tabs 11 and negative electrode tabs 21 form two distinct and closely arranged tab regions on the same end of the battery. This makes the space of the non-tab region 33 larger than that of the tab region. The non-tab region 33 can form an electrolyte wetting channel, which facilitates the electrolyte wetting of the cell 3.

[0071] In some embodiments, cutting the electrode assembly further includes: adjusting the circumference L of each turn of the cell 3 according to an empirical coefficient, L n =G*πD n Where G is an empirical coefficient, and G is greater than or equal to 0.98 and less than or equal to 1.02.

[0072] It is understandable that in actual production, the positive and negative electrode materials will be stretched and compressed, and there will also be tension changes and slippage during the winding process of the battery cell 3. Therefore, the theoretical value needs to be multiplied by an empirical coefficient for fine adjustment in order to correct the error and better ensure that each positive electrode tab 11 is perfectly stacked after winding, and each negative electrode tab 21 is also perfectly stacked.

[0073] Secondly, referring to Figures 2 to 6 As shown, this application also provides a battery cell 3, which includes a positive electrode 1 and a negative electrode 2 wound together. The positive electrode 1 includes a positive electrode tab 11, and the negative electrode 2 includes a negative electrode tab 21. The positive electrode tab 11 and the negative electrode tab 21 respectively form a positive electrode tab region 31 and a negative electrode tab region 32 at the same end of the battery cell 3. An end face wetting region is formed between the positive electrode tab region 31 and the negative electrode tab region 32. The end face wetting region radially isolates the positive electrode tab region 31 and the negative electrode tab region 32 along the end face of the battery cell.

[0074] In the battery cell 3 of this application embodiment, since an end-face wetting area is formed between the positive electrode tab region 31 and the negative electrode tab region 32, compared with the method of wetting by winding the center hole in related technologies, the end-face wetting area can more conveniently wet the battery cell 3 from the side of the battery cell 3, thereby improving the liquid injection efficiency of the battery cell 3.

[0075] In some embodiments, the positive electrode 1 includes a plurality of positive electrode tabs 11; and / or, the negative electrode 2 includes a plurality of negative electrode tabs 21.

[0076] This allows the electrode to be connected to other devices through multiple tabs, ensuring a good connection.

[0077] In some embodiments, a plurality of positive electrode tabs 11 overlap along the width direction of the positive electrode tab 11; and / or, a plurality of negative electrode tabs 21 overlap along the width direction of the negative electrode tab 21.

[0078] Thus, the positive electrode tabs 11 overlap in the width direction, forming a smaller positive electrode tab area 31 on the end face of the cell 3. Under the same conditions, this allows for a larger end face wetting area, facilitating electrolyte wetting and ensuring injection efficiency. Similarly, the negative electrode tabs 21 overlap in the width direction, forming a smaller negative electrode tab area 32 on the end face of the cell 3. Under the same conditions, this allows for a larger end face wetting area, facilitating electrolyte wetting and ensuring injection efficiency.

[0079] Furthermore, since the positive electrode tab region 31 and the negative electrode tab region 32 occupy a small proportion on the end face of the cell 3, the electrolyte can more evenly wet the cell 3, thereby improving the energy density of the cell.

[0080] In some embodiments, the widths of the plurality of positive electrode tabs 11 are the same, but the distances between two adjacent positive electrode tabs 11 are unequal; and / or, the widths of the plurality of negative electrode tabs 21 are the same, but the distances between two adjacent negative electrode tabs 21 are unequal.

[0081] Understandably, as the thickness of the battery cell 3 increases continuously during winding, in this embodiment, the distance between two adjacent positive electrode tabs 11 gradually increases, so that the positive electrode tabs 11 can overlap in the radial direction of the end face of the battery cell 3 during winding to form a small positive electrode tab region 31; similarly, the distance between two adjacent negative electrode tabs 21 gradually increases, so that the negative electrode tabs 21 can overlap in the radial direction of the end face of the battery cell 3 during winding to form a small negative electrode tab region 32.

[0082] In some embodiments, the positive electrode tab region 31 and the negative electrode tab region 32 are symmetrically arranged.

[0083] In this way, the two non-tab regions 33 formed between the positive electrode tab region 31 and the negative electrode tab region 32 can be of uniform size, thereby making the electrolyte penetration uniform, improving the uniformity of current distribution, and extending the cycle life of the battery.

[0084] In some embodiments, refer to Figure 4 and Figure 5 As shown, the heights of the multiple positive electrode tabs 11 are not equal; and / or, the heights of the multiple negative electrode tabs 21 are not equal.

[0085] Thus, compared to the consistent height of the positive electrode tab 11 and the consistent height of the negative electrode tab 21 in related technologies, setting the heights of multiple positive electrode tabs 11 and multiple negative electrode tabs 21 to be unequal can avoid the problem of the electrode completely wrapping the end face of the core after winding, and also avoid the problem of the tabs sticking too tightly to each other after the tabs are flattened, making it difficult for the electrolyte to penetrate from the side, resulting in low electrolyte injection efficiency, poor electrolyte retention coefficient, and affecting the battery cycle life.

[0086] In some embodiments, a plurality of positive electrode tabs 11 are arranged in a stepped manner along the direction of the diameter of the battery cell 3; and / or, a plurality of negative electrode tabs 21 are arranged in a stepped manner along the direction of the diameter of the battery cell 3.

[0087] It is understood that in this embodiment, since the heights of the multiple positive electrode tabs 11 are not equal, the multiple positive electrode tabs 11 will overlap in stages, thereby forming a stepped overlap surface; similarly, since the heights of the multiple negative electrode tabs 21 are not equal, the multiple negative electrode tabs 21 will overlap in stages, thereby forming a stepped overlap surface.

[0088] This prevents the tabs from sticking too tightly together after being flattened, allowing the electrolyte to seep in from the sides and improving the electrolyte injection efficiency of cell 3.

[0089] Thus, the stepped tab design makes the current distribution inside the cell 3 more uniform, which can better disperse the current and avoid the current from concentrating at a certain point, thereby reducing local overheating and uneven aging of the electrode material.

[0090] In this embodiment, the height of the plurality of positive electrode tabs 11 gradually decreases along the direction from the inner layer to the outer layer of the battery cell 3; and / or, the height of the plurality of negative electrode tabs 21 gradually decreases along the direction from the inner layer to the outer layer of the battery cell 3.

[0091] However, this design is not limited to this. In other embodiments, the height of the plurality of positive electrode tabs 11 can also gradually increase along the direction from the inner layer to the outer layer of the cell 3, or the height of the plurality of negative electrode tabs 21 can also gradually increase.

[0092] In some embodiments, the ratio of the tallest positive electrode tab 11 to the shortest positive electrode tab 11 is greater than 1 and less than or equal to 2; and / or, the ratio of the tallest negative electrode tab 21 to the shortest negative electrode tab 21 is greater than 1 and less than or equal to 2.

[0093] Thus, the ratio of the tallest positive electrode tab 11 to the shortest positive electrode tab 11 is between 1 and 2, and the ratio of the tallest negative electrode tab 21 to the shortest negative electrode tab 21 is between 1 and 2. This ensures that the current distribution is uniform and that the structural strength is not affected by the large difference in the height of the tabs.

[0094] Thus, the battery cell 3 manufactured by the battery cell 3 manufacturing method in this application, under the same other conditions, can reduce the internal resistance of the battery cell 3 by more than 35%, improve the rate performance by 40%, improve the current distribution uniformity by 50%, extend the cycle life by 30%, improve the material and space utilization, increase the energy density by 6%, improve the thermal distribution uniformity of the battery cell 3 by 60%, reduce the risk of thermal runaway, improve the reliability of the electrode connection, and reduce the failure rate by 50%.

[0095] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0096] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0097] The embodiments, implementation methods, and related technical features of this application can be combined and substituted for each other without conflict.

[0098] The above are merely preferred embodiments of this application and are not intended to limit this application in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application without departing from the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. A method for preparing a battery cell, wherein the battery cell (3) comprises an electrode assembly, the electrode assembly comprising a positive electrode (1) and a negative electrode (2), characterized in that, include: Cutting the electrode assembly includes cutting the blank foil at the edge of the positive electrode (1) to form a positive electrode tab (11) and cutting the blank foil at the edge of the negative electrode (2) to form a negative electrode tab (21). The electrode assembly is wound so that the positive electrode tab (11) and the negative electrode tab (21) form a positive electrode tab region (31) and a negative electrode tab region (32) at the same end of the cell (3), respectively. An end face wetting region is formed between the positive electrode tab region (31) and the negative electrode tab region (32), and the end face wetting region isolates the positive electrode tab region (31) and the negative electrode tab region (32) radially along the end face of the cell.

2. The method for preparing a battery cell according to claim 1, characterized in that, The cutting of the electrode assembly further includes: Cut out multiple positive electrode tabs (11) and / or multiple negative electrode tabs (21); and / or, The winding of the electrode assembly further includes: Along the width direction of the positive electrode tab (11), a plurality of the positive electrode tabs (11) overlap; and / or, along the width direction of the negative electrode tab (21), a plurality of the negative electrode tabs (21) overlap.

3. The method for preparing a battery cell according to claim 1, characterized in that, The cutting of the electrode assembly further includes: Multiple positive electrode tabs (11) are cut out, wherein the widths of the multiple positive electrode tabs (11) are the same, and the distances between two adjacent positive electrode tabs (11) are unequal; and / or, Multiple negative electrode tabs (21) are cut out, wherein the widths of the multiple negative electrode tabs (21) are the same, and the distances between two adjacent negative electrode tabs (21) are not equal.

4. The method for preparing a battery cell according to claim 3, characterized in that, The cutting of the electrode assembly includes: Determine the starting point of the winding of the electrode assembly; The starting position of the first positive electrode tab (11) on the positive electrode sheet (1) is set based on the winding start point, and the starting position of the first negative electrode tab (21) on the negative electrode sheet (2) is determined; wherein, the positive electrode tab area (31) and the negative electrode tab area (32) are set at a preset angle α, and the distance between the first positive electrode tab (11) and the first negative electrode tab (21) is α / 360 of the circumference of the first turn of the electrode assembly after winding; And cut out the first positive electrode tab (11) on the positive electrode plate (1) and the first negative electrode tab (21) on the negative electrode plate (2) according to the determined position.

5. The method for preparing a battery cell according to claim 4, characterized in that, The positive electrode tab area (31) and the negative electrode tab area (32) are arranged at a 180° interval, and the distance between the first positive electrode tab (11) and the first negative electrode tab (21) is half the circumference of the first turn of the electrode assembly after winding.

6. The method for preparing a battery cell according to claim 5, characterized in that, The electrode assembly further includes a separator located between the positive electrode (1) and the negative electrode (2), and the cutting of the electrode assembly further includes: Calculate the circumference L of each turn of the wound cell (3) sequentially. n L n =πD n D n =T core +2n(T) anode +T cathode +2T sep ); Among them, D n T is the diameter of the nth turn of the battery cell (3); core T is the diameter of the first coil of the battery cell (3); anode T is the thickness of the negative electrode sheet (2); cathode T is the thickness of the positive electrode sheet (1). sep The thickness of the diaphragm; A first spacing is formed between every two adjacent positive electrode tabs (11), and each of the first spacings E is determined sequentially. n And cut out multiple positive electrode tabs (11) according to multiple first spacings, wherein, E n =L n ; and / or, A second spacing is formed between every two adjacent negative electrode tabs (21), and each second spacing F is determined sequentially. n And cut out multiple negative electrode tabs (21) according to multiple second spacings, wherein, F n =L n .

7. The method for preparing a battery cell according to claim 5, characterized in that, The cutting of the electrode assembly further includes: The circumference L of each turn of the battery cell (3) is corrected according to an empirical coefficient. n =G*πD n ; Wherein, G is an empirical coefficient, and G is greater than or equal to 0.98 and less than or equal to 1.

02.

8. A battery cell, characterized in that, The battery cell (3) includes a positive electrode (1) and a negative electrode (2) wound together. The positive electrode (1) includes a positive electrode tab (11), and the negative electrode (2) includes a negative electrode tab (21). The positive electrode tab (11) and the negative electrode tab (21) form a positive electrode tab region (31) and a negative electrode tab region (32) at the same end of the battery cell (3), respectively. An end face wetting region is formed between the positive electrode tab region (31) and the negative electrode tab region (32). The end face wetting region isolates the positive electrode tab region (31) and the negative electrode tab region (32) radially along the end face of the battery cell.

9. The battery cell according to claim 8, characterized in that, The positive electrode (1) includes a plurality of positive electrode tabs (11); and / or, the negative electrode (2) includes a plurality of negative electrode tabs (21).

10. The battery cell according to claim 9, characterized in that, Along the width direction of the positive electrode tab (11), a plurality of the positive electrode tabs (11) overlap; and / or, Along the width direction of the negative electrode tab (21), a plurality of negative electrode tabs (21) overlap.

11. The battery cell according to claim 10, characterized in that, The positive electrode tabs (11) of the plurality of said positive electrode tabs (11) have the same width, the distance between two adjacent positive electrode tabs (11) is not equal, and / or, The widths of the multiple negative electrode tabs (21) are the same, and the distances between two adjacent negative electrode tabs (21) are not equal.

12. The battery cell according to claim 8, characterized in that, The positive electrode tab region (31) and the negative electrode tab region (32) are arranged symmetrically.

13. The battery cell according to claim 8, characterized in that, The heights of the plurality of positive electrode tabs (11) are not equal; and / or the heights of the plurality of negative electrode tabs (21) are not equal.

14. The battery cell according to claim 13, characterized in that, Along the direction of the diameter of the battery cell (3), a plurality of positive electrode tabs (11) are arranged in a stepped manner; and / or, along the direction of the diameter of the battery cell (3), a plurality of negative electrode tabs (21) are arranged in a stepped manner.

15. The battery cell according to claim 13 or 14, characterized in that, Along the direction from the inner layer to the outer layer of the battery cell (3), the height of the plurality of positive electrode tabs (11) gradually decreases; and / or, along the direction from the inner layer to the outer layer of the battery cell (3), the height of the plurality of negative electrode tabs (21) gradually decreases.

16. The battery cell according to any one of claims 9-15, characterized in that, The ratio of the highest positive electrode tab (11) to the lowest positive electrode tab (11) is greater than 1 and less than or equal to 2; and / or, The ratio of the highest negative electrode tab (21) to the lowest negative electrode tab (21) is greater than 1 and less than or equal to 2.

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