Winding battery, design method thereof and foil resistance calculation method

Abstract

The application provides a winding battery and a design method and foil resistance calculation method thereof. The foil resistance calculation method comprises the following steps: S1, determining the mathematical spiral mode of the winding core and the size information of the diaphragm, the positive electrode sheet and the negative electrode sheet; S2, establishing a polar coordinate system and determining a pole point and a pole axis; S3, fitting the spiral equation of the diaphragm, the positive electrode sheet and the negative electrode sheet in the polar coordinate; and S4, fitting the parameter equation of the welding wire in the polar coordinate system, combining the spiral equation and the parameter equation, solving all intersection points, each intersection point corresponding to a welding point, generating the geometric solid foil of the positive electrode foil or the negative electrode foil according to the welding point information, and calculating the resistance value of the geometric solid foil through a simulation experiment. The welding point information is solved through a mathematical model, and the resistance value of the geometric solid foil is calculated through a simulation experiment. The resistance value of the positive electrode foil or the negative electrode foil can be quickly calculated without actually winding and welding the winding core, the rapid screening and optimization of the welding wire design are realized.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a wound battery and its design method and foil resistance calculation method. Background Technology

[0002] A wound battery typically consists of a core, an electrolyte, and a casing. The two ends of the casing form the external positive and negative electrodes, respectively. The electrolyte serves as the ion transport medium, and the core converts chemical energy into electrical energy. The core is usually formed by winding four layers sequentially: a separator, a negative electrode sheet, another separator, and a positive electrode sheet. The negative electrode sheet includes a negative electrode foil and a negative electrode material layer coated on at least one surface of the foil. The positive electrode sheet includes a positive electrode foil and a positive electrode material layer coated on at least one surface of the foil. After winding, one end of the positive electrode sheet forms a cylinder connected to the external positive electrode of the casing, while the other end of the negative electrode sheet forms a cylinder connected to the external negative electrode of the casing.

[0003] A common core winding process involves first loosely winding the separator to a predetermined length using a fixed winding needle. Then, the negative electrode sheet is inserted between the two separator layers and wound together with the separator to a predetermined length. Finally, the positive electrode sheet is attached to the outside of the separator, achieving co-winding of the separator, negative electrode sheet, and positive electrode sheet, until the core winding is complete. The predetermined length of the loosely wound separator is the separator insertion length, and the predetermined length of the negative electrode sheet wound together with the separator is the negative electrode insertion length. After the negative electrode foil is wound, the resulting end face is welded to the negative current collector and then connected to the external negative electrode of the casing. Similarly, after the positive electrode foil is wound, the resulting end face is welded to the positive current collector and then connected to the external positive electrode of the casing.

[0004] Typically, the end faces of the positive and negative electrode foils are linearly welded to the positive and negative current collectors, respectively. For example, CN117219972B discloses connecting the current collector to the end face of the coiled foil using three linear welding lines, and CN112290168B discloses connecting it using three or five linear welding lines. The length, number, and arrangement of the welding lines all affect the conductive path of the foil. Different conductive paths result in different resistance values ​​even with the same foil material and thickness, leading to different internal resistance conditions in the resulting battery system. Therefore, a method is urgently needed to quickly calculate the resistance values ​​of the positive or negative electrode foils under different welding line designs, providing a theoretical basis for evaluating the quality of the current collector welding line design or optimizing the current collector welding line design. Summary of the Invention

[0005] To address the aforementioned issues and enable rapid calculation of the resistance value of the positive or negative electrode foil within the battery system under a given wire bonding design, the first aspect of this application provides a foil resistance calculation method, comprising the following steps:

[0006] S1: Based on the winding pattern of the core, determine the mathematical spiral pattern, thickness, width in the height direction of the core, and corresponding winding arc length of the diaphragm, positive electrode, and negative electrode in the orthographic projection view of the end face of the core.

[0007] S2: Establish a polar coordinate system in the orthographic projection view of the end face of the core, with the geometric center of the winding needle in the orthographic projection view of the end face of the core as the pole and the line connecting the pole and the starting winding point of the diaphragm as the polar axis.

[0008] S3: Fit the spiral equations of the diaphragm, the positive electrode, and the negative electrode within the polar coordinates; and

[0009] S4: Fit the parametric equation of the welding wire in the polar coordinate system according to the shape, size, quantity and orientation of the welding wire. Solve the helical equation and the parametric equation simultaneously to find all intersection points. Each intersection point corresponds to the geometric center of a welding point. Generate a geometric solid foil material of positive or negative electrode foil material according to the size information of the welding point. Calculate the resistance value of the geometric solid foil material through simulation experiments.

[0010] In some optional embodiments, the mathematical spiral is an Archimedean spiral, and the polar radius r and polar angle θ satisfy the relationship: r = a + bθ, where a is the polar radius at the starting winding point, b is the radius increment per unit polar angle, and arc length arc of the spiral between polar angles θ1 and θ2. l satisfy:

[0011] In some alternative embodiments, establishing the helical equations for the winding arc length, polar angle, and polar diameter further includes the following steps:

[0012] S31: With the aforementioned needle radius r a The polar diameter of the starting winding point for the diaphragm insertion is determined, along with the diaphragm thickness sep. t With input length Insertion length of negative electrode With the winding arc length neg l Thickness of negative electrode foil Neg of negative electrode material layer thickness t The arc length of the positive electrode (pos) l Thickness of the positive electrode foil and the thickness of the cathode material layer pos t ;as well as

[0013] S32: Based on the radius increment of the unit polar angle during the empty winding of the diaphragm. bThe radius increment of the unit polar angle when the negative electrode is inserted is neg. b And the radius increment pos of the unit pole angle during the winding of the positive electrode sheet. b The polar angle and polar diameter of the insertion endpoint of the diaphragm and the negative electrode, as well as the polar angle and polar diameter of the winding endpoint of the positive electrode, are calculated respectively, and the spiral equations of the polar angle, polar diameter and arc length of the negative electrode and the positive electrode are established respectively.

[0014] In some alternative implementations, S32 further includes the following step:

[0015] S321: The sep b From the formula The relationship between the polar diameter and polar angle during the diaphragm insertion stage is obtained as follows: r sep =r a +sep b θ sep The diaphragm insertion length is Establish relation I: Where θ0=0, the polar angle of the diaphragm insertion endpoint is solved. further, Solve for the polar diameter of the diaphragm insertion endpoint.

[0016] S322: The neg b From the formula The relationship between the polar diameter and polar angle during the negative electrode insertion stage is obtained as follows: The insertion endpoint of the diaphragm is the insertion starting point of the negative electrode sheet, based on the insertion length of the negative electrode sheet. Establish relation II: Solve for the polar angle at the endpoint of the negative electrode insertion. further, Solve for the polarity of the negative electrode at the insertion end point.

[0017] S323: The pos b From the formula It is determined that the insertion end point of the negative electrode is the winding start point of the positive electrode, based on the winding arc length pos of the positive electrode. l Establish relation III: Solve for the polar angle at the end of the winding of the positive electrode. Further according to the formula Solve for the polarity r of the winding endpoint of the positive electrode. b ;as well as

[0018] S324: The length of the spiral segment between any two polar angles θ1 and θ2 of the positive electrode plate satisfies: The arc length of the spiral between any two polar angles θ1 and θ2 during the insertion phase of the negative electrode sheet satisfies: The arc length of the spiral between any two polar angles θ1 and θ2 during the co-winding stage of the negative electrode and the positive electrode after the insertion stage satisfies: The For the diaphragm in Polar radius at the polar angle

[0019] In some optional implementations, the solution methods for relation I to relation III include at least one of heuristic algorithms and numerical optimization algorithms. The heuristic algorithms include genetic algorithms, particle swarm optimization, differential evolution, and ant colony optimization. The numerical optimization algorithms include least squares, bisection, gradient descent, Newton's method, and conjugate gradient.

[0020] In some alternative implementations, S4 further includes the following step:

[0021] S41: The line connecting the geometric symmetry center of each weld wire to the pole forms a weld wire polar angle. List the weld wire polar angles θ for all the weld wires. list And corresponding to the polar angle list θ of the bonding wire list The parametric equations of the corresponding bonding wires are matched, and the parametric equations of the bonding wires are solved simultaneously with the helical equations of the positive or negative electrode. Using the range of the polar diameter of each bonding wire as a constraint, n intersection points are obtained between all the bonding wires and the negative or positive electrode. Each intersection point corresponds to dividing the helical line of the negative or positive electrode into n+1 arc segments. The arc length of each arc segment is solved. Based on the bonding wire width w, the intersection points are corrected to the bonding points, and the foil length gap corresponding to the arc length is obtained. length The list yields (gap) length , w);

[0022] S42: Based on the list of foil lengths and solder joint widths between every two adjacent solder joints (gap... length (w) Combining the thickness of the corresponding positive or negative electrode foil, the winding arc length parameter of the positive or negative electrode sheet, and the width parameter of the positive or negative electrode sheet in the height direction of the winding core, a geometric entity corresponding to the foil is generated in the finite element software; and

[0023] S43: Perform a simulation experiment in the finite element software, input the three-dimensional geometric parameters of the geometric solid foil and the geometric parameters of each of the solder joints, input a specified current I to the geometric solid foil using the solder joints as the current input terminals, calculate the average potential Vup of the current input terminal and the potential Vlb of the ground terminal using the finite element method based on the conductivity coefficient σ of the foil, and output the resistance value of the geometric solid foil.

[0024] In some alternative embodiments, the parametric equation of the welding wire is used to describe the welding trajectory of the welding wire in the polar coordinate system. The welding trajectory is a straight line or curve of finite length. The distance between the endpoint of the welding trajectory near the pole and the pole is d1, and the width of the welding trajectory in the polar radial direction of the polar coordinate system is d2.

[0025] In some optional embodiments, the welding trajectory is a straight line whose extension passes through the pole, and the width of each welding line is w. The combination of polar angles corresponding to each welding trajectory is the welding line polar angle list θ. list The (gap) length The method for solving the w) list includes the following steps:

[0026] S411: Determine the helical equation r(θ) = a + bθ of the positive or negative electrode where the solder joint is located, determine the parameters a, b, and the effective polar radius range [r1, r2] of the helix, and input θ. list Input the polar diameter range [d1, d1+d2] for each of the welding trajectories, and the width w of the welding line;

[0027] S412: Define the arc-length integral formula Any two polar angles θ star to polar angle θ end The formula for calculating the arc length between arcs is: arc length a,b,θ star ,θ end )=L(a,b,θ end -L(a,b,θ star S413: Initialize θ to 0, obtain θ list For any polar angle θ1, with the constraint r1≤r(θ1)≤r2, calculate the polar radius d=r(θ1). If d∈d1,d1+d2, then calculate the arc length: length sec =L(θ1)-L(0), record θ1, d, length sec Set the increment to 2π, update θ = θ1 + 2π, recalculate r(θ), and merge all θ, d, and length values ​​on the weld line corresponding to θ1 that meet the conditions. sec ;

[0028] S414: Traverse θ list For each polar angle value, record θ, d, and length on all bonding wires that satisfy the conditions. sec S415: Sort θ, d, and length in ascending order based on the value of θ. sec Based on the width w data of the weld wire, the length is corrected. sec For gap length gap length =length sec -w;

[0029] S416: θ, d, length sec The first set of data in the table corresponds to [θa, da, length]. seca The last set of data corresponds to: [θb,db,length] secb The total length L of the helix, the helix including the first arc segment: Final arc And all the middle arcs except the first and last arcs; and

[0030] S417: Output the first arc segment (gap) lengtha , w), the middle arc of each group (gap) length ,w) and the final arc gapl eng thb.

[0031] In some alternative implementations, the (gap) length The solution method for the list (w) can be converted into a computer programming language for application on a computer terminal, wherein the computer programming language includes at least one of Java, C, C++ and MathLab.

[0032] In some alternative implementations, S43 further includes the following step:

[0033] S431: Input the three-dimensional geometric parameters of the geometric entity foil and the geometric parameters of each of the solder joints;

[0034] S432: Based on the actual foil material properties used, define the conductivity σ, define the potential Vlb of the grounding terminal face to be equal to 0, and preset the normal component of the current to be zero;

[0035] S433: Input a specified current I into the geometric foil material using the solder joint as the current input terminal, where each solder joint corresponds to a node on the current input terminal face;

[0036] S434: Extract the potential value V of each node on the current input terminal face. iCalculate the area weight Dai for each node, and then calculate the average potential value of all nodes using a weighted average to obtain V. up ;as well as

[0037] S435: The resistance R of the geometric solid foil is: R = (V up -V lb ) / I.

[0038] In some alternative implementations, the finite element software includes at least one of: croe, solidwork, cossol, ansys, and ABAQUS.

[0039] A second aspect of this application provides a method for designing a wound battery, the method comprising the following steps:

[0040] S01: Determine the three-dimensional dimensions of the separator, negative electrode, positive electrode, and winding needle, as well as the winding method of the core; S02: Design the bonding schemes for the positive electrode foil and negative electrode foil to the corresponding positive electrode current collector and negative electrode current collector, respectively;

[0041] S03: Calculate the resistance of the positive electrode foil or the negative electrode foil according to the foil resistance calculation method described in any of the above items;

[0042] S04: Adjust the three-dimensional dimensions of the separator, negative electrode, positive electrode and winding needle, the winding method of the core and the wire bonding scheme until the battery design scheme with the lowest resistance of the positive electrode foil or negative electrode foil is selected.

[0043] A third aspect of this application provides a wound battery, which is a wound battery designed according to the design method described above.

[0044] Furthermore, the wound battery is a lithium-ion cylindrical battery.

[0045] This application has at least the following technical effects:

[0046] 1) The first aspect of this application provides a method for calculating the resistance of foil in a wound battery. By establishing a polar coordinate system in the orthographic projection view of the end face of the core, and taking the geometric center of the winding needle in the orthographic projection view of the end face of the core as the pole, and the line connecting the pole and the starting winding point of the separator as the polar axis, the spiral equations of the separator, the positive electrode, and the negative electrode are fitted in a mathematical spiral manner. Combined with the parametric equations of the bonding wire, all intersections of the spiral and the bonding wire are solved by solving the simultaneous equations, thereby determining the three-dimensional geometric parameters of the geometric solid foil and the distribution of the bonding points. The resistance of the geometric solid foil is calculated through simulation experiments. Without actually winding the core and welding it to the current collector, the resistance of the positive or negative electrode foil under a determined bonding wire design in the battery system can be quickly calculated. This saves time and effort, and can also quickly screen the bonding wire design with lower interface contact resistance. It can also provide a theoretical basis for evaluating the quality of the current collector bonding wire design or optimizing the current collector bonding wire design.

[0047] 2) The second aspect of this application provides a design method for a wound battery. Using the above-mentioned foil resistance calculation method, parameters can be adjusted from multiple dimensions such as the winding method of the core, the three-dimensional size information of the separator, negative electrode, positive electrode and winding needle, and the wire bonding design. By comparing the resistance of the positive electrode foil or negative electrode foil in the battery system under various parameters, the direction of battery design optimization can be determined, the resistance of the positive electrode foil or negative electrode foil in the battery system can be minimized, and the optimal battery design scheme can be formed.

[0048] 3) A third aspect of this application provides a wound battery in which the positive and negative electrode foils obtained by the above design method can be adapted to the optimal wire bonding layout design, thereby minimizing the resistance in the battery system, reducing energy loss when current passes through, improving the charging and discharging efficiency and stability of the battery, extending service life and improving safety performance. Attached Figure Description

[0049] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application 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.

[0050] Figure 1 This is a three-dimensional structural diagram of the unfolded core portion of a wound battery according to an optional embodiment of this application;

[0051] Figure 2 This is a schematic diagram of the bonding wire on the end face of the core in Embodiment 1 of this application;

[0052] Figure 3This is a schematic diagram of the geometric solid foil generated in the finite element software after solving for the information of the weld point and the arc length of the segment in Embodiment 1 of this application;

[0053] Figure 4 This is a partial enlarged view of the current input end face of the negative electrode foil in Embodiment 1 of this application;

[0054] Figure 5 This is a schematic diagram of the bonding wire on the end face of the core in Embodiment 2 of this application;

[0055] Figure 6 This is a schematic diagram of the bonding wire on the end face of the core in Embodiment 3 of this application;

[0056] Figure 7 This is a planar schematic diagram of the inner separator, negative electrode, and positive electrode being co-wound, showing the core end face of a wound battery according to an optional embodiment of this application.

[0057] Figure reference numerals: 2-core, 21-positive electrode sheet, 210-positive electrode active material layer, 212-positive electrode foil, 23-separator, 25-negative electrode sheet, 250-negative electrode active material layer, 252-negative electrode foil, 3-welding wire, 30-welding point, 32-arc segment. Detailed Implementation

[0058] The embodiments of this implementation are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this implementation, and should not be construed as limiting this implementation.

[0059] In the description of this embodiment, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this embodiment and simplifying the description, 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 embodiment.

[0060] In the description of this embodiment, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0061] In the description of this embodiment, unless otherwise explicitly limited, terms such as setting, installing, and connecting should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this embodiment in conjunction with the specific content of the technical solution.

[0062] The first aspect of this application provides a method for calculating the foil resistance of a wound battery. The method includes the following steps:

[0063] S1: Based on the winding pattern of the core 2, determine the mathematical spiral pattern, thickness, width in the height direction of the core 2, and corresponding winding arc length of the diaphragm 23, positive electrode 21, and negative electrode 25 in the orthographic projection view of the end face of the core 2.

[0064] S2: Establish a polar coordinate system in the orthographic projection view of the end face of the core 2, with the geometric center of the winding needle in the orthographic projection view of the end face of the core 2 as the pole and the line connecting the pole and the starting winding point of the diaphragm 23 as the polar axis.

[0065] S3: Fit the spiral equations of the winding arc length, polar angle, and polar diameter of the diaphragm 23, the positive electrode 21, and the negative electrode 25 within the polar coordinates; and

[0066] S4: Fit the parametric equation of the solder wire 3 in the polar coordinate system according to the shape, size, quantity and orientation of the solder wire 3. Solve the helical equation and the parametric equation simultaneously to find all intersection points. Each intersection point corresponds to the geometric center of a solder point 30. Generate a geometric solid foil material of positive electrode foil 212 or negative electrode foil 252 according to the size information of the solder point 30. Calculate the resistance value of the geometric solid foil material through simulation experiments.

[0067] Furthermore, the mathematical spiral pattern is an Archimedean spiral, and the polar radius r and polar angle θ satisfy the relationship: r = a + bθ, where a is the polar radius at the starting winding point, b is the radius increment per unit polar angle, and arc length arc of the spiral between polar angles θ1 and θ2. l satisfy:

[0068] It should be noted that, taking the positive electrode 21 as an example, the positive electrode 21 is formed by coating a positive electrode material on at least one side of the positive electrode foil 212. After the positive electrode material is cured, the positive electrode material layer 210 is formed. Therefore, the positive electrode foil 212 and the positive electrode material layer 210, and the negative electrode foil 252 and the negative electrode material layer 250 can all be regarded as sheet-like wholes. Furthermore, the spiral equation of the positive electrode 21 can be equivalent to the spiral equation of the positive electrode foil 212, and the spiral equation of the negative electrode 25 can be equivalent to the spiral equation of the negative electrode foil 252.

[0069] By establishing a polar coordinate system in the orthographic projection view of the end face of the core 2, and taking the geometric center of the winding needle in the orthographic projection view of the end face of the core 2 as the pole, and the line connecting the pole and the starting winding point of the separator 23 as the polar axis, the spiral equations of the separator 23, the positive electrode 21, and the negative electrode 25 are fitted in a mathematical spiral manner. Combined with the parametric equations of the bonding wire 3, all intersections of the spiral and the bonding wire 3 are solved by solving the simultaneous equations, thereby determining the three-dimensional geometric parameters of the geometric solid foil and the distribution of the bonding points 30. The resistance value of the geometric solid foil is calculated through simulation experiments. Without actually winding the core 2 and welding it to the current collector, the resistance value of the positive electrode foil 212 or the negative electrode foil 252 under the determined bonding wire 3 design can be quickly calculated in the battery system. This saves time and effort, and can also quickly screen the bonding wire 3 design with lower interface contact resistance. At the same time, it provides a theoretical basis for evaluating the design quality of the current collector bonding wire 3 or optimizing the current collector bonding wire 3 design.

[0070] In some alternative implementations, establishing the helical equations for the winding arc length, polar angle, and polar diameter further includes the following steps:

[0071] S31: With the aforementioned needle radius r a The polar diameter of the starting winding point of the diaphragm 23 is determined, and the parameters are: the thickness of the diaphragm 23 is sep. t With input length Insertion length of negative electrode 25 With the winding arc length neg l The thickness of the negative electrode foil 252 Neg 250mm thick anode material layer t The winding arc length of the positive electrode 21 is pos l The thickness of the positive electrode foil 212 and the cathode material layer with a thickness of 210 pos t ;as well as

[0072] S32: Based on the radius increment of the unit polar angle when the diaphragm 23 is unwound during insertion, sep b The radius increment of the unit polar angle when the negative electrode 25 is in place is neg. b And the radius increment pos of the unit pole angle when the positive electrode 21 is wound. b The polar angle and polar diameter of the insertion endpoint of the diaphragm 23 and the negative electrode 25, and the polar angle and polar diameter of the winding endpoint of the positive electrode 21 are respectively calculated, and the spiral equations of the polar angle, polar diameter and arc length of the negative electrode 25 and the positive electrode 21 are respectively established.

[0073] In some alternative implementations, S32 further includes the following step:

[0074] S321: The sepb From the formula The relationship between the polar radius and polar angle of the diaphragm 23 during the insertion stage is obtained as follows: r sep =r a +sep b θ sep The insertion length of the diaphragm 23 is Establish relation I: Where θ0=0, the polar angle of the endpoint of the diaphragm 23 is solved. further, Solve for the polar diameter of the endpoint of the diaphragm 23.

[0075] S322: The neg b From the formula The relationship between the polar diameter and polar angle of the negative electrode 25 during the insertion stage is obtained as follows: The insertion endpoint of the diaphragm 23 is the insertion starting point of the negative electrode 25, based on the insertion length of the negative electrode 25. Establish relation II: Solve for the polar angle of the negative electrode plate 25 at the end point of the insertion position. further, Solve for the polarity of the negative electrode 25 at the insertion end point. as well as

[0076] S323: The pos b From the formula It is determined that the insertion end point of the negative electrode 25 is the winding start point of the positive electrode 21, based on the winding arc length pos of the positive electrode 21. l Establish relation III: Solve for the polar angle of the winding endpoint of the positive electrode 21. Further according to the formula Solve for the polarity r of the winding endpoint of the positive electrode 21. b ;as well as

[0077] S324: The length of the arc segment 32 of the spiral between any two polar angles θ1 and θ2 of the positive electrode 21 satisfies: The length of the arc segment 32 of the spiral between any two polar angles θ1 and θ2 during the insertion phase of the negative electrode 25 satisfies: The arc length of the spiral between any two polar angles θ1 and θ2 during the co-winding stage of the negative electrode 25 and the positive electrode 21 after the positioning stage satisfies: The For the diaphragm 23 in Polar radius at the polar angle

[0078] In the specific implementation process, the thickness of the diaphragm 23 is sep t The thickness of the negative electrode 25, ranging from 6 to 20 μm, includes the thickness of the negative electrode foil 252. and the thickness of the negative electrode material layer is 250. t Normally, The range is 4-15 μm, the neg t The thickness ranges from 50 to 200 μm, and the thickness of the positive electrode 21 includes the thickness of the positive electrode foil 212. The thickness pos of the positive electrode material layer 210 t Normally, The range is 6-20 μm, and the pos t The range is 60-200 μm. Furthermore, the neg... t With pos t This corresponds to the total thickness of the negative electrode material and the positive electrode material, i.e., when both sides of the foil are coated with material, neg t With pos t This corresponds to the total thickness of the double-sided material.

[0079] It should be noted that, see Figure 1 and Figure 7 During the winding of the core 2, the separator 23 is pre-wound on the winding needle. The separator 23 comprises two layers, with the thickness increment being twice the thickness of the separator 23 per winding turn. The negative electrode 25 begins to be positioned between the two separator layers. Its initial electrode diameter should be the final electrode diameter of the inner separator 23. However, since the thickness of the separator 23 differs from the thickness of the negative electrode 25 by several times, to simplify the helical equation, the two separator layers 23 are not further distinguished. The initial electrode diameter of the negative electrode 25 is simplified to the final electrode diameter of the separator 23, which is also the final electrode diameter of the outer separator 23. Furthermore, during the stage where the negative electrode 25 is co-wound with the positive electrode 21 after its insertion, the initial electrode diameter of the negative electrode 25 also corresponds to the θ of the separator 23 at the end of the negative electrode 25's insertion. negs The extreme diameter r at that location sepu .

[0080] In the specific implementation process, the solution methods for relation I to relation III include at least one of heuristic algorithms and numerical optimization algorithms. The heuristic algorithms include genetic algorithms, particle swarm optimization, differential evolution, and ant colony optimization. The numerical optimization algorithms include least squares, bisection, gradient descent, Newton's method, and conjugate gradient method. All of the above methods can be used to solve for the polar angle values ​​within relation I to relation III.

[0081] In some alternative implementations, S4 further includes the following step:

[0082] S41: The line connecting the geometric symmetry center of each of the bonding wires 3 to the pole forms a bonding wire polar angle. List the bonding wire polar angles θ of all the bonding wires 3. list And corresponding to the polar angle list θ of the bonding wire list The parametric equations of the corresponding bonding wires 3 are matched, and the parametric equations of the bonding wires 3 are solved simultaneously with the helical equations of the positive electrode 21 or the negative electrode 25. Using the range of the polar diameter of each bonding wire 3 as a constraint, n intersection points are obtained between all bonding wires 3 and the negative electrode 25 or the positive electrode 21. These intersection points divide the helical lines corresponding to the negative electrode 25 or the positive electrode 21 into n+1 arc segments 32. The arc length of each arc segment 32 is solved. Based on the width w data of the bonding wires 3, the intersection points are corrected to the bonding points 30, and the foil length gap corresponding to the length of the arc segment 32 is obtained. length The list yields (gap) length , w);

[0083] S42: Based on the list of foil lengths and widths of every two adjacent solder joints 30 (gap) length (w) Combining the thickness of the corresponding positive electrode foil 212 or negative electrode foil 252, the winding arc length data of the positive electrode 21 or negative electrode 25, and the width data of the positive electrode 21 or negative electrode 25 in the height direction of the core 2, the geometric entity corresponding to the foil is generated in the finite element software.

[0084] S43: Perform a simulation experiment in the finite element software. Input the three-dimensional geometric parameters of the geometric solid foil and the geometric parameters of each of the solder joints 30. Input a specified current I into the geometric solid foil using the solder joints 30 as the current input terminals. Based on the conductivity coefficient σ of the foil, calculate the average potential Vup of the current input terminal and the potential Vlb of the ground terminal using the finite element method. Output the resistance value of the geometric solid foil.

[0085] In some alternative implementations, the parametric equation of the welding wire 3 is used to describe the welding trajectory of the welding wire 3 in the polar coordinate system. The welding trajectory is a straight line or curve of finite length. The distance between the endpoint of the welding trajectory near the pole and the pole is d1, and the width of the welding trajectory in the polar radial direction of the polar coordinate system is d2.

[0086] In some alternative implementations, the welding trajectory is a straight line whose extension passes through the pole, and the width of each welding line 3 is w. The combination of polar angles corresponding to each welding trajectory is the welding line polar angle list θ. listThe (gap) length The method for solving the w) list includes the following steps:

[0087] S411: Determine the helical equation r(θ) = a + bθ of the positive electrode 21 or negative electrode 25 where the solder joint 30 is located, determine the parameters a, b, and the effective polar radius range [r1, r2] of the helix, and input θ. list Input the polar diameter range [d1, d1+d2] of each welding trajectory, and the width w of the welding line 3;

[0088] S412: Define the arc-length integral formula Any two polar angles θ star to polar angle θ end The formula for calculating the length of the arc segment between arcs is: arc length (a,b,θ star ,θ end )=L(a,b,θ end )-L(a,b,θ star );

[0089] S413: Initialize θ to 0, obtain θ list For any polar angle θ1, with constraints r1 ≤ r(θ1) ≤ r2, calculate the polar radius d = r(θ1). If d ∈ d1, d1 + d2, then calculate the arc length: length sec =L(θ1)-L(0), record θ1, d, length sec Set the increment to 2π, update θ = θ1 + 2π, recalculate r(θ), and merge all θ, d, and length values ​​on the weld line 3 corresponding to θ1 that meet the conditions. sec ;

[0090] S414: Traverse θ list For each polar angle value, record θ, d, and length on all bonding wires 3 that satisfy the conditions. sec S415: Sort θ, d, and length in ascending order based on the value of θ. sec Based on the width w data of the weld wire 3, the length is adjusted. sec For gap length gap length =length sec -w;

[0091] S416: θ, d, length sec The first set of data in the table corresponds to [θa, da, length]. seca The last set of data corresponds to: [θb,db,length] secbThe total length L of the helix, the helix including the first arc segment: Final arc And all the middle arcs except the first and last arcs; and

[0092] S417: Output the first arc segment (gap) lengtha , w), the middle arc of each group (gap) length ,w) and the final arc gapl eng thb.

[0093] It is understandable that when weld line 3 is a straight line, the parametric equation of weld line 3 corresponds to the equation of the welding trajectory: θ = θ0, r ∈ d1, d1 + d2, and the resulting intersection points are the set {θ0, r0, θ1 + 2π, r1, ..., θ1 + 2nπ, r}. n}, where n is an integer.

[0094] Alternatively, the weld line 3 can also be a curve. A common type of curved weld line 3 is the S-shaped weld line. The S-shaped weld line 3 can be sinusoidal or piecewise symmetrical. Taking the sinusoidal S-shaped weld line 3 as an example, first define the spiral equation r(θ) = a + bθ. The equation of the S-shaped weld line 3 in polar coordinates is: r s =d1+d2sin(θ), where d1 is the distance between the endpoint of the S-curve closest to the pole and the pole, and d2 is the width of the S-curve's extension in the polar radius direction. Solving the simultaneous equations a+bθ=d1+d2sin(θ), we get the nonlinear equation: f(θ)=a+bθ-d1-d2sin(θ)=0. Further, using heuristic algorithms such as genetic algorithms, particle swarm optimization, differential evolution, and ant colony optimization, or numerical optimization algorithms such as least squares method, bisection method, gradient descent method, Newton's method, and conjugate gradient method, we obtain a numerical solution. After obtaining the numerical solution, referring to the above method, we correct the intersection point to weld point 30 and output the corresponding first arc segment (gap). lengtha , w), the middle arc of each group (gap) length , w) and the final arc gap lengthb .

[0095] It should be further noted that the width w of the weld line 3 is determined by the welding procedure. Normally, without considering operational or system errors, the width of the weld line 3 is consistent during continuous welding operations. Therefore, the width of the same weld line 3 should be equal everywhere. However, the widths of different weld lines 3 can differ. Therefore, in the above steps, the width information of each weld line 3 can be supplemented, and the initial arc (gap) can be corrected with a relative width value based on the information of the weld line 3 where the weld point 30 is located. lengtha w a ), the middle arc (gap) of each group length w iand the final arc gap lengthb This has certain practical applications in actual production design. Taking the straight welding line 3 as an example, the closer to the outer edge of the spiral, the longer the arc segment 32 between every two welding points 30. Therefore, the arc segment length between welding points 30 can be adjusted by increasing the width of the welding line 3 at the outer edge, or by adding welding lines 3 at the outer edge (see...). Figure 5 and Figure 6 The arc length of the arc segment 32 between solder points 30 is adjusted using a certain method. On the other hand, directly correcting the intersection point to solder point 30 using the width value w of the solder wire 3 is based on the fact that the width w of the solder wire 3 is much smaller than the spiral length L. Therefore, to reduce computational load, the curvature of the foil covered by solder point 30 is ignored, and the length of the foil covered by solder point 30 is approximately equal to the width of the solder wire 3. In scenarios requiring higher precision, the width of solder point 30 can be further corrected to the arc length of the foil to obtain more accurate solder point 30 size data. For example, the polar angles corresponding to the endpoints of the width W of solder point 30 can be determined, and the arc length between the two polar angle values ​​can be solved using the arc length integral formula.

[0096] In the specific implementation process, some or all of the bonding wires 3 have the characteristic of rotational symmetry about the poles. After confirming the intersection information of a bonding wire 3, the intersection information of bonding wires 3 that have a symmetrical relationship with it can be quickly solved by using the symmetric mapping method, which reduces the amount of calculation to a certain extent and reduces the computing power requirement of the computer.

[0097] In some alternative implementations, the (gap) length The solution method for the list (w) can be converted into a computer programming language for application on a computer terminal. The computer programming language includes at least one of Java, C, C++, and MathLab. The above solution process can be programmed using a computer in a programming language, achieving more efficient computation.

[0098] In some alternative implementations, the simulation experiment calculation of the foil resistance within the finite element software further includes the following steps:

[0099] S431: Input the three-dimensional geometric parameters of the geometric entity foil and the geometric parameters of each of the solder joints 30; S432: Define the conductivity σ according to the actual foil material properties used, define the potential Vlb of the grounding terminal face to be equal to 0, and preset the current normal component to be zero;

[0100] S433: Input a specified current I into the geometric foil material using the solder joint 30 as the current input terminal, where each solder joint 30 corresponds to a node on the current input terminal face;

[0101] S434: Extract the potential value V of each node on the current input terminal face. iCalculate the area weight Dai for each node, and then calculate the weighted average potential value of all nodes to obtain V. up ;as well as

[0102] S435: The resistance R of the geometric solid foil is: R = (V up -V lb ) / I.

[0103] In some alternative implementations, the finite element software includes at least one of the following: croe, solidwork, cossol, ansys, and ABAQUS. All of these software programs possess corresponding computer-aided design, finite element calculation, and simulation experiment functions.

[0104] A second aspect of this application provides a method for designing a wound battery, the method comprising the following steps:

[0105] S01: Determine the three-dimensional dimensions of the diaphragm 23, negative electrode 25, positive electrode 21, and winding needle, as well as the winding method of the core 2;

[0106] S02: Design a bonding wire 3 scheme for the positive electrode foil 212 and the negative electrode foil 252 to the corresponding positive electrode current collector and negative electrode current collector, respectively;

[0107] S03: Calculate the resistance of the positive electrode foil 212 or the negative electrode foil 252 according to the foil resistance calculation method described above;

[0108] S04: Adjust the three-dimensional dimensions of the separator 23, negative electrode 25, positive electrode 21 and winding needle, the winding method of the core 2 and the bonding wire 3 scheme until the battery design scheme with the lowest resistance of the positive electrode foil 212 or the negative electrode foil 252 is selected.

[0109] Using the above-mentioned foil resistance calculation method, parameters can be adjusted from multiple dimensions, including the winding method of the core 2, the three-dimensional dimensions of the separator 23, negative electrode 25, positive electrode 21 and winding needle, and the design of the bonding wire 3. By comparing the resistance of the positive electrode foil 212 or negative electrode foil 252 in the battery system under various parameters, the direction of battery design optimization can be determined, the resistance of the positive electrode foil 212 or negative electrode foil 252 in the battery system can be minimized, and the optimal battery design scheme can be formed.

[0110] A third aspect of this application provides a wound battery, which is a wound battery designed according to the design method described above. The wound battery obtained by the above design method allows the positive and negative electrode foils to be adapted to an optimal bonding wire arrangement design, thereby minimizing the resistance within the battery system, reducing energy loss during current flow, improving the battery's charging and discharging efficiency and stability, extending its service life, and enhancing safety performance.

[0111] Furthermore, the wound battery is a lithium-ion cylindrical battery.

[0112] The technical solution of this application is described below with reference to Examples 1-3. In Examples 1-3, a lithium-ion cylindrical battery of model 21700 is used as the target battery. The height of the core 2 is 70mm and the diameter is 21mm.

[0113] Example 1:

[0114] See Figures 2-4 In Example 1, the thickness of diaphragm 23 is: sep t =12e -3 mm, needle radius: r a =1.75mm, diaphragm 23 insertion length: Neg material layer thickness 250 t =9.5e -2 mm, negative electrode foil thickness 252: Negative electrode 25mm insertion length: The thickness of the positive electrode material layer 210 is: pos t =7.7e -2 mm, thickness of positive electrode foil 212: The winding arc length of the negative electrode 25: neg l =1493mm, the width of each weld line is w: w=0.5mm;

[0115] Polar Angle List for Bond 3

[0116] The distance from the center of the bonding wire 3 to the core is d1 = 3.85 mm, the length of the bonding wire 3 is d2 = 3.85 mm, the current is I = 4 A, and the conductivity of the foil is σ = 5.8 e. 7 Based on the S / m, the resistance of the negative electrode foil 252 is calculated to be 13.56μΩ.

[0117] Example 2:

[0118] See Figure 5 In Example 2, the thickness of diaphragm 23 is: sep t =12e -3 mm, needle radius: r a =1.75mm, diaphragm 23 insertion length: Neg material layer thickness 250 t =9.5e -2 mm, negative electrode foil thickness 252: Negative electrode 25mm insertion length: The thickness of the positive electrode material layer 210 is: pos t =7.7e-2 mm, thickness of positive electrode foil 212: The winding arc length of the negative electrode 25: neg l =1493mm, the width of each welding line 3 is w: w=0.5mm, the distance of welding line 3 from the center of the roll core d1=[3.85,5.35,6.85]mm, the length of welding line 3 d2=[4.5,3,1.5]mm;

[0119] List of polar angles for wire bonding 3:

[0120] Current I = 4A, conductivity σ of negative electrode foil 252 = 5.8e 7 Based on the S / m, the resistance of the negative electrode foil 252 is calculated to be 16.59 μΩ.

[0121] Example 3:

[0122] See Figure 6 In Example 3, the thickness of diaphragm 23 is: sep t =12e -3 mm, needle radius: r a =1.75mm, diaphragm 23 insertion length: Neg material layer thickness 250 t =9.5e -2 mm, negative electrode foil thickness 252 Negative electrode insertion length The thickness of the positive electrode material layer 210 is: pos t =7.7e - 2 mm, thickness of positive electrode foil 212: The winding arc length of the positive electrode 21: pos l =1411mm, the width of each weld line 3 is w: w=0.5mm, the distance of weld line 3 from the pole is d1=[3.55,6.55,5.05,3.55]mm, the length of weld line 3 is d2=[4.5,1.5,3,1.5]mm;

[0123] List of polar angles for wire bonding 3:

[0124]

[0125] Current: I = 4A; Conductivity of positive electrode foil 212: σ = 3.5e 7 The resistance of the positive electrode foil was calculated to be 19.49 μΩ based on the S / m.

[0126] The resistance data calculated from Examples 1-2 show that foils of the same material and size exhibit resistance differences of up to 18% under different bonding wire designs. This confirms that the interfacial contact resistance of the positive and negative electrode foils is one of the key variables in the battery's internal resistance. Traditional methods for testing foil resistance require resistance calibration through physical battery experiments, which has drawbacks such as long testing cycles and high equipment costs. The foil resistance calculation method provided in this application can quickly calculate the resistance of the positive or negative electrode foil within the battery system under a given bonding wire design without conducting physical battery experiments. This provides a theoretical tool for the forward design of battery internal resistance, and is particularly suitable for the development of next-generation batteries that are sensitive to interfaces, such as high-nickel ternary / silicon-carbon systems, demonstrating significant technological foresight.

[0127] In the description of this specification, references to the terms "some embodiments," "an embodiment," or similar descriptions mean that a specific feature, structure, material, or characteristic described in connection with that embodiment is included in at least one embodiment or example. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0128] Although embodiments of this implementation have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this implementation, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for calculating the resistance of foil, characterized in that, Includes the following steps: S1: Based on the winding pattern of the core, determine the mathematical spiral pattern, thickness, width in the height direction of the core, and corresponding winding arc length of the diaphragm, positive electrode, and negative electrode in the orthographic projection view of the end face of the core. The mathematical spiral pattern is an Archimedean spiral, and the polar radius r and polar angle θ satisfy the relationship: r = a + bθ, where a is the polar radius at the starting winding point, b is the radius increment per unit polar angle, and the arc length of the spiral between polar angles θ1 and θ2 is... satisfy: S2: Establish a polar coordinate system in the orthographic projection view of the end face of the core, with the geometric center of the winding needle in the orthographic projection view of the end face of the core as the pole and the line connecting the pole and the starting winding point of the diaphragm as the polar axis; S3: Fit the spiral equations of the winding arc length, polar angle and polar diameter of the diaphragm, the positive electrode and the negative electrode in the polar coordinate system; and S4: Fit the parametric equations of the welding wire in the polar coordinate system according to the shape, size, quantity and orientation of the welding wire, solve the spiral equations and the parametric equations simultaneously, solve for all intersection points, each intersection point corresponds to the geometric center of a welding point, generate the geometric solid foil of the positive electrode foil or the negative electrode foil according to the size information of the welding point, and calculate the resistance value of the geometric solid foil through simulation experiments; wherein, the establishment of the spiral equations of the winding arc length, polar angle and polar diameter also includes the following steps: S31: with the radius of the winding needle For the polar diameter of the starting winding point of the diaphragm insertion, determine the following parameters: diaphragm thickness. With input length The insertion length of the negative electrode plate With the winding arc length Thickness of negative electrode foil Thickness of the negative electrode material layer The winding arc length of the positive electrode plate Thickness of the positive electrode foil and the thickness of the cathode material layer ; and S32: based on the radius increment of the unit polar angle when the diaphragm is inserted into the empty roll. The radius increment per unit polar angle when the negative electrode is inserted and the radius increment per unit pole angle during the winding of the positive electrode sheet. The polar angle and polar diameter of the insertion endpoint of the diaphragm and the negative electrode, as well as the polar angle and polar diameter of the winding endpoint of the positive electrode, are calculated respectively, and the spiral equations of the polar angle, polar diameter and arc length of the negative electrode and the positive electrode are established respectively.

2. The method for calculating the resistance of foil according to claim 1, characterized in that, The S32 also Includes the following steps: S321: the From the formula The relationship between the polar diameter and polar angle during the diaphragm insertion stage is obtained as follows: The diaphragm insertion length is Establish relation I: ,in =0, solve for the polar angle of the diaphragm insertion endpoint. ,further, Solve for the polar diameter of the diaphragm insertion endpoint. S322: The aforementioned From the formula The relationship between the polar diameter and polar angle during the negative electrode insertion stage is obtained as follows: The insertion endpoint of the diaphragm is the insertion starting point of the negative electrode sheet, based on the insertion length of the negative electrode sheet. Establish relation II: Solve for the polar angle at the endpoint of the negative electrode insertion. ,further, The polar diameter of the negative electrode insert end point is calculated. S323: The aforementioned From the formula It is determined that the endpoint of the negative electrode is the starting point of the winding of the positive electrode, based on the winding arc length of the positive electrode. Establish relation III: Solve for the polar angle at the winding endpoint of the positive electrode plate. Further according to the formula The polar diameter at the winding endpoint of the positive electrode is determined. ; and S324: The arc length of the spiral between any two polar angles θ1 and θ2 of the positive electrode plate satisfies: , The arc length of the spiral between any two polar angles θ1 and θ2 during the insertion phase of the negative electrode sheet satisfies: , The arc length of the spiral between any two polar angles θ1 and θ2 during the co-winding stage after the negative electrode is in place and with the positive electrode satisfies: , The For the diaphragm in Polar radius at the polar angle .

3. The method for calculating the resistance of foil according to claim 2, characterized in that, The methods for solving relation I to relation III include at least one of heuristic algorithms and numerical optimization algorithms. The heuristic algorithms include genetic algorithms, particle swarm optimization, differential evolution, and ant colony optimization. The numerical optimization algorithms include least squares, bisection, gradient descent, Newton's method, and conjugate gradient.

4. The method for calculating the resistance of foil according to claim 1, characterized in that, The S4 also The steps include: S41: The line connecting the geometric symmetry center of each bonding wire to the pole forms a bonding wire pole angle, and a list of bonding wire pole angles for all the bonding wires is compiled. And corresponding to the list of bonding wire polar angles The parametric equations of the corresponding bonding wires are matched, and the parametric equations of the bonding wires are solved simultaneously with the helical equations of the positive or negative electrode. Using the range of the polar diameter of each bonding wire as a constraint, n intersection points are obtained between all the bonding wires and the negative or positive electrode. Each intersection point corresponds to dividing the helical line of the negative or positive electrode into n+1 arc segments. The arc length of each arc segment is solved. Based on the bonding wire width w, the intersection points are corrected to the bonding points, and the foil length corresponding to the arc length is obtained. , get a list ( S42: Based on the foil length between every two adjacent solder joints and the list ( S41: Combining the thickness of the corresponding positive or negative electrode foil, the winding arc length parameter of the positive or negative electrode, and the width parameter of the positive or negative electrode in the height direction of the core, a geometric entity corresponding to the foil is generated in the finite element software; and S42: A simulation experiment is performed in the finite element software, the three-dimensional geometric parameters of the geometric entity foil and the geometric parameters of each solder joint are input, a specified current I is input to the geometric entity foil with the solder joint as the current input terminal, and the average potential Vup of the current input terminal and the potential Vlb of the ground terminal are calculated by the finite element method according to the conductivity coefficient σ of the foil, and the resistance value of the geometric entity foil is output.

5. The method for calculating the resistance of foil according to claim 4, characterized in that, The parametric equation of the welding wire is used to describe the welding trajectory of the welding wire in the polar coordinate system. The welding trajectory is a straight line or curve of finite length, and the distance between the endpoint of the welding trajectory near the pole and the pole is... The width of the welding trajectory in the polar radial direction of the polar coordinate system is .

6. The method for calculating the resistance of foil according to claim 5, characterized in that, The welding trajectory is a straight line whose extension passes through the pole, and the width of each welding line is w. The combination of polar angles corresponding to each welding trajectory is the welding line polar angle list. The list ( Solution method for ) Includes the following steps: S411: Determine the helical equation of the positive or negative electrode where the solder joint is located. Determine parameters a, b, and the effective polar radius range [r1, r2] of the helix, and input... Input the polar radius range [d1, d1+d2] for each welding trajectory, and the width w of the weld line; S412: Define the arc length integral formula. Any two polar angles to polar angle The formula for calculating the length of the arc segment between them is: ; S413: Initialize θ to 0, obtain... Any polar angle value ,constraint Calculate the polar radius ,if Then calculate the length of the arc segment: ),Record Set the increment to 2π and update θ= +2π, recalculate r(θ), and combine. All of the corresponding bonding wires that meet the conditions S414: Traversal For each polar angle value, record all bonding wires that meet the conditions. ; S415: Sort in ascending order based on the value of θ. Based on the width w data of the weld wire, the correction is performed. for , S416: The first set of data in [ ] corresponds to [ ] The last set of data corresponds to: [ The total length L of the helix, the helix including the first arc segment: Final arc And the middle arcs of each group except the first and last arcs; and S417: output the first arc ( ), the middle arc of each group ( ) and the final arc .

7. The method for calculating the resistance of foil according to claim 6, characterized in that, The list ( The solution method can be converted into a computer programming language and applied to a computer terminal, wherein the computer programming language includes at least one of Java, C, C++ and MathLab.

8. The method for calculating the resistance of foil according to claim 4, characterized in that, The S43 also The process includes the following steps: S431: Input the three-dimensional geometric parameters of the geometric solid foil and the geometric parameters of each solder joint; S432: Define the conductivity σ according to the actual foil material properties used, define the potential Vlb of the grounding terminal face to be equal to 0, and preset the current normal component to be zero; S433: Input a specified current I into the geometric solid foil using the solder joint as the current input terminal, with each solder joint corresponding to a node on the current input terminal face; S434: Extract the potential value V of each node on the current input terminal face. i Calculate the area weight Dai for each node, and then calculate the weighted average potential value of all nodes to obtain V. up ; and S435: The resistance R of the geometric solid foil is: .

9. The method for calculating the resistance of foil according to claim 4, characterized in that, The finite element software includes at least one of the following: croe, solidwork, cossol, ansys, and ABAQUS.

10. A design method for a wound battery, characterized in that, The design method of the wound battery includes the following steps: S01: Determine the three-dimensional dimensions of the separator, negative electrode sheet, positive electrode sheet, and winding needle, as well as the winding method of the core; S02: Design the bonding schemes for the positive electrode foil and negative electrode foil to the corresponding positive electrode current collector and negative electrode current collector, respectively; S03: Calculate the resistance value of the positive electrode foil or negative electrode foil according to the foil resistance calculation method according to any one of claims 1-9; S04: Adjust the three-dimensional dimensions of the separator, negative electrode sheet, positive electrode sheet, and winding needle, the winding method of the core, and the bonding scheme until the battery design scheme with the lowest resistance value of the positive electrode foil or negative electrode foil is selected.

11. A wound battery, characterized in that, The wound battery is a wound battery designed according to the design method described in claim 10.

12. The wound battery according to claim 11, characterized in that, The wound battery is a lithium-ion cylindrical battery.

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