Calculation method and system for forming of multiple tabs of cylindrical battery

Abstract

The method comprises the following steps: S1, taking a roll core with the diameter of 58 mm as an example, and according to the specific parameters, the diameter of a center hole is 8 mm, the length of a positive plate is 7000 mm, the thickness is 184 [mu] m (the thickness of an aluminum foil is 13 [mu] m), the length of a negative plate is 7200 mm, the thickness is 140 [mu] m (the thickness of a copper foil is 6 [mu] m), the thickness of a diaphragm is 12 [mu] m, the gap between tabs is 0.1 mm (the diameter of a laser spot), and the tab length design is as follows: the inner ring (rb is 8-12 mm) Le is 4 mm; the middle ring (rb: 12-20mm) is 6mm, and the outer ring (rb: 20-29mm) Le is 4mm; according to the tab forming method provided by the invention, after the tab is folded, the end surface is flat and uniformly stacked, the contact resistance is reduced, the battery performance and safety are improved, the end surface structure is optimized through the 60-degree tab design, and the situation that the edge of the end surface extends out of the outer side of a roll core body due to backward movement of the folding position in the 60-degree tab folding process is avoided. The method is suitable for manufacturing high-capacity cylindrical lithium batteries.

Description

Technical Field

[0001] This invention relates to the field of cylindrical lithium battery manufacturing technology, and in particular to a calculation method and system for forming multi-tabs in cylindrical batteries. Background Technology

[0002] In existing technologies, tab formation is one of the key processes in the manufacturing of cylindrical lithium batteries. Traditional tab formation methods often involve cutting or welding after winding, which can easily lead to problems such as uneven tab end faces, high contact resistance, and increased internal resistance of the battery. In addition, uneven tab stacking may cause battery performance degradation and safety hazards.

[0003] In existing technologies, the tab shape is mostly T-shaped. The folded rear end face is prone to step-like bumps, which affects the current collection effect and safety of the battery. In addition, the T-shaped tab cutting process will generate waste material edges, resulting in waste.

[0004] Therefore, this application proposes a calculation method and system for forming multi-tabs in cylindrical batteries to solve the above problems. Summary of the Invention

[0005] Given the existing technical issues that the tabs are mostly T-shaped, and the folded rear end face is prone to step-like unevenness, affecting the current collection efficiency and safety of the battery; and that the T-shaped tab cutting process generates waste material edges, resulting in technical problems, this invention proposes a calculation method and system for forming multiple tabs in cylindrical batteries.

[0006] The present invention proposes a calculation method and system for forming multi-tabs in cylindrical batteries, comprising the following steps: S1: Parameter settings: Taking a 58mm diameter core as an example, the specific parameters are as follows: Center hole diameter: 8mm; Positive electrode length: 7000mm, thickness 184μm (aluminum foil thickness 13μm). Negative electrode length: 7200mm, thickness 140μm (copper foil thickness 6μm); Diaphragm thickness: 12μm; Electrode gap: 0.1mm (laser spot diameter); Tab length design: Inner ring (rb: 8-12mm) Le=4mm, middle (rb: 12-20mm) = 6mm, outer ring (rb: 20-29mm) Le=4mm; S2: Electrode cutting: A die-cutting machine is used to make slit cuts in the empty foil area of ​​the positive and negative electrode sheets. The first tab of the positive electrode sheet is located 433.3 mm from the starting end, and the calculation for the negative electrode sheet is similar. S3: Winding: The cut electrode sheets and diaphragm are wound together into a core, and the electrode sheets are pre-folded by a pre-folding wheel during winding. S4: Clasp folding: After winding, the electrode tabs are formed by two gathering mechanisms and two flattening mechanisms. The electrode tabs are folded and flattened towards the end face so that the inner electrode tabs cover the edge of the center hole. S5: Stacking layer verification: The number of stacked layers on the end face is calculated by formula. For example, at r=10mm, N(10)=17.2 layers; at r=4mm, N(4)=11.5 layers. The middle area with a higher number of stacked layers (r=12-20mm) is the key area for welding the manifold.

[0007] Preferably, according to S1, a die-cutting machine is used to slit-cut the empty foil area of ​​the electrode sheet before winding, so that the electrode tab is formed into a parallelogram with a cutting angle of 60°.

[0008] Furthermore, the empty foil area of ​​the electrode sheet is cut at a 60° angle using a die-cutting machine to form parallelogram-shaped tabs. This cutting angle allows the hypotenuses of adjacent tabs to nest together after folding, significantly improving the flatness of the end face. This design reduces unevenness caused by uneven stacking, enhancing the overall structural stability and current conduction efficiency of the battery.

[0009] Preferably, the electrode gap is the diameter of the laser spot, typically 0.1 mm.

[0010] Furthermore, the tab gap is designed to be the same as the laser spot diameter (0.1mm). This design ensures high precision during tab cutting and reduces material waste. The precise cutting gap maximizes production efficiency and minimizes material loss during production, thereby reducing production costs.

[0011] Preferably, both the positive and negative tabs adopt a design with a short inner ring, a long middle ring, and a short outer ring, with the tab length in the range of 4-6mm.

[0012] Furthermore, the design employs a tab shape with a short inner ring, a long middle ring, and a short outer ring, which can adapt to the winding requirements at different radius positions. This design allows the tab length to vary within the range of 4-6mm, not only optimizing the shape of the tabs but also ensuring that the tabs at different positions can be evenly covered during the winding process, avoiding battery performance instability caused by tabs that are too long or too short.

[0013] Preferably, the starting position of the electrode cutting is calculated so that the inner electrode is folded and flattened to cover the edge of the central hole.

[0014] Furthermore, the calculation method for the starting position of the tab cutting ensures that the inner tab, after folding, can precisely cover the edge of the center hole. This precise calculation avoids situations where the tab fails to completely cover the center hole, guaranteeing the battery's sealing and structural integrity, thereby improving the battery's lifespan and safety.

[0015] Preferably, the number of tab stacking layers at each radial position on the end face of the core is calculated by the formula N(r) = Le(r) / teff, where N(r) is the tab length at the coverage radius r, and teff is the effective winding thickness.

[0016] Furthermore, by calculating the number of tab stacking layers at each radial position on the end face of the core using a formula, the tab thickness and stacking quantity at different radii can be accurately determined. This calculation provides a theoretical basis for the welding area of ​​the current collector, ensuring optimal welding strength and current conduction during the welding process, thereby improving the overall performance of the battery.

[0017] A system for implementing the above method includes a die-cutting machine, a winding machine, and a control unit, characterized in that: the die-cutting machine is configured to perform 60° parallelogram cutting, and the control unit adjusts the cutting position according to calculated parameters.

[0018] Furthermore, the system design of this invention can automatically adjust the tab cutting position. Combined with the cooperation of the die-cutting machine, winding machine, and control unit, it can achieve efficient and precise tab cutting and winding operations. This system reduces human intervention during production, improves production efficiency, and ensures accurate tab cutting and folding, further enhancing battery performance and production stability.

[0019] The beneficial effects of this invention are: The tab forming method provided by this invention results in a flat and uniformly stacked rear end face after tab folding, reducing contact resistance and improving battery performance and safety. The 60° tab design optimizes the end face structure, and the 60° tab folding process prevents the end face edge from extending beyond the outer side of the core body due to rearward shift of the folding position. It is suitable for the manufacture of high-capacity cylindrical lithium batteries. Attached Figure Description

[0020] Figure 1 The flowchart proposed in this invention; Figure 2 This is a schematic diagram of the electrode slit cutting structure proposed in this invention; Figure 3 This is a schematic diagram of the parallelogram-shaped pole lug and the 60° cutting angle proposed in this invention. Figure 4 This is a schematic diagram of the stacking of the end face tabs of the winding core proposed in this invention; Figure 5This is a schematic diagram of the coverage area of ​​the display electrode proposed in this invention; Figure 6 This is a schematic diagram of the stacking layer distribution proposed in this invention; Figure 7 This is a schematic diagram of the flatness of the first conventional folding end face proposed in this invention; Figure 8 This is a schematic diagram of the flatness of the second conventional folding end face proposed in this invention; Figure 9 This is a schematic diagram illustrating the flatness of the folded end face proposed in this invention. Detailed Implementation

[0021] The present invention will be further explained below with reference to specific embodiments.

[0022] Reference Figure 1-9 Example 1 This embodiment proposes a calculation method and system for forming multi-tabs in cylindrical batteries, including the following steps: S1: Parameter settings: Taking a 58mm diameter core as an example, the specific parameters are as follows: Center hole diameter: 8mm; Positive electrode length: 7000mm, thickness 184μm (aluminum foil thickness 13μm). Negative electrode length: 7200mm, thickness 140μm (copper foil thickness 6μm); Diaphragm thickness: 12μm; Electrode gap: 0.1mm (laser spot diameter); Tab length design: Inner ring (rb: 8-12mm) Le=4mm, middle (rb: 12-20mm) = 6mm, outer ring (rb: 20-29mm) Le=4mm; S2: Electrode cutting: A die-cutting machine is used to make slit cuts in the empty foil area of ​​the positive and negative electrode sheets. The first tab of the positive electrode sheet is located 433.3 mm from the starting end, and the calculation for the negative electrode sheet is similar. S3: Winding: The cut electrode sheets and diaphragm are wound together into a core, and the electrode sheets are pre-folded by a pre-folding wheel during winding. S4: Clasp folding: After winding, the electrode tabs are formed by two gathering mechanisms and two flattening mechanisms. The electrode tabs are folded and flattened towards the end face so that the inner electrode tabs cover the edge of the center hole. S5: Stacking layer verification: The number of stacked layers on the end face is calculated by formula. For example, at r=10mm, N(10)=17.2 layers; at r=4mm, N(4)=11.5 layers. The middle area with a higher number of stacked layers (r=12-20mm) is the key area for welding the manifold.

[0023] Preferably, according to S1, a die-cutting machine is used to slit-cut the empty foil area of ​​the electrode sheet before winding, so that the electrode tab is formed into a parallelogram with a cutting angle of 60°.

[0024] Furthermore, the empty foil area of ​​the electrode sheet is cut at a 60° angle using a die-cutting machine to form parallelogram-shaped tabs. This cutting angle allows the hypotenuses of adjacent tabs to nest together after folding, significantly improving the flatness of the end face. This design reduces unevenness caused by uneven stacking, enhancing the overall structural stability and current conduction efficiency of the battery.

[0025] Preferably, the electrode gap is the diameter of the laser spot, typically 0.1 mm.

[0026] Furthermore, the tab gap is designed to be the same as the laser spot diameter (0.1mm). This design ensures high precision during tab cutting and reduces material waste. The precise cutting gap maximizes production efficiency and minimizes material loss during production, thereby reducing production costs.

[0027] Preferably, both the positive and negative tabs adopt a design with a short inner ring, a long middle ring, and a short outer ring, with the tab length in the range of 4-6mm.

[0028] Furthermore, the design employs a tab shape with a short inner ring, a long middle ring, and a short outer ring, which can adapt to the winding requirements at different radius positions. This design allows the tab length to vary within the range of 4-6mm, not only optimizing the shape of the tabs but also ensuring that the tabs at different positions can be evenly covered during the winding process, avoiding battery performance instability caused by tabs that are too long or too short.

[0029] Preferably, the starting position of the electrode cutting is calculated so that the inner electrode is folded and flattened to cover the edge of the central hole.

[0030] Furthermore, the calculation method for the starting position of the tab cutting ensures that the inner tab, after folding, can precisely cover the edge of the center hole. This precise calculation avoids situations where the tab fails to completely cover the center hole, guaranteeing the battery's sealing and structural integrity, thereby improving the battery's lifespan and safety.

[0031] Preferably, the number of tab stacking layers at each radial position on the end face of the core is calculated by the formula N(r) = Le(r) / teff, where N(r) is the tab length at the coverage radius r, and teff is the effective winding thickness.

[0032] Furthermore, by calculating the number of tab stacking layers at each radial position on the end face of the core using a formula, the tab thickness and stacking quantity at different radii can be accurately determined. This calculation provides a theoretical basis for the welding area of ​​the current collector, ensuring optimal welding strength and current conduction during the welding process, thereby improving the overall performance of the battery.

[0033] A system for implementing the above method includes a die-cutting machine, a winding machine, and a control unit, characterized in that: the die-cutting machine is configured to perform 60° parallelogram cutting, and the control unit adjusts the cutting position according to calculated parameters.

[0034] Furthermore, the system design of this invention can automatically adjust the tab cutting position. Combined with the cooperation of the die-cutting machine, winding machine, and control unit, it can achieve efficient and precise tab cutting and winding operations. This system reduces human intervention during production, improves production efficiency, and ensures accurate tab cutting and folding, further enhancing battery performance and production stability.

[0035] Working Principle: Before winding, a die-cutting machine is used to slit the empty foil areas of the positive and negative electrode sheets, forming parallelogram-shaped tabs at a 60° angle. This angle design ensures that the beveled edges of adjacent tabs nest together after folding, resulting in a flatter end face. The tab gap is equal to the laser spot diameter, typically 0.1mm, to minimize material waste and ensure cutting accuracy. Both positive and negative tabs adopt a design with a short inner ring, a long middle ring, and a short outer ring, with the tab length varying within the range of 4-6mm. The inner ring tab length is set to 4mm, the middle tab length to 6mm, and the outer ring tab length to 4mm, to accommodate changes in circumference at different radii during winding, ensuring uniform stacking height at the folded end face. The starting position of the tab cutting is calculated so that the inner ring tab, after folding and flattening, just covers the edge of the center hole. Taking a center hole diameter of 8mm as an example, the radius of the inner ring tab base needs to be 4mm +Le (Le is the tab length) to determine the cutting start point on the electrode sheet. The number of tab stacking layers at each radial position on the end face of the core is calculated by formula to ensure uniform stacking. The formula is derived based on the winding geometry parameters and the tab coverage area. For the positive electrode, the relationship between the winding radius r and the electrode length s is as follows: , Among them, r0 = 4mm is the radius of the central hole (the radius varies for different battery models. In this invention, the 60150 battery is taken as an example), and teff = tp + tn + 2*ts is the effective thickness, where tp = 0.184mm (thickness of the positive electrode sheet), tn = 0.140mm (thickness of the negative electrode sheet), and ts = 0.012mm (thickness of the separator). It is obtained that: r2 = 16 + 0.1108s. Similarly, for the negative electrode sheet, the starting position of cutting is calculated using the same formula: after the inner - loop tab is folded, it covers the edge of the central hole (radius 4mm). Therefore, the radius of the tab base rb = 4 + Le. Taking the positive electrode as an example, when Le = 4mm, then rb = 8mm. Substituting into the formula 82 = 16 + 0.1108s, we get: s = 433.3mm, that is, the starting position of the first tab cutting on the positive electrode sheet is 433.3mm; Calculation of the tab stacking layer number: The tab stacking layer number refers to the number of layers covered by the tabs at a certain radial position r on the end face of the core. The calculation is based on the winding layer number and the tab coverage range. For the tab stacking layer number N(r) at the end - face radius r, N(r)=Le(r) / teff, where Le(r) is the length of the tab covering the radius r, and teff = 0.348mm. Since the tab length is designed to be short in the inner loop (4mm), long in the middle (6mm), and short in the outer loop (4mm), therefore: When r ≤ 12mm or r ≥ 20mm, Le(r)=4mm, then N(r)=4 / 0.348 = 12 layers, When 12mm < r < 20mm, Le(r)=6mm, then N(r)=6 / 0.348 = 17 layers.

[0036] Through calculation, we can calculate the stacking layer number and thickness of the tabs at each position on the end face of the core, providing a theoretical basis for calculating the welding area of the current collector plate in subsequent welding.

[0037] Calculation of the tab number: To meet the tab number for rb - Le ≤ r ≤ rb, since the tab gap is small (about 0.1mm, which is the diameter of the laser - cutting light spot), it can be approximately calculated continuously.

[0038] For example, for r = 4.5mm, the tab - covering range is from 8mm to 8.5mm, corresponding to s from 433.3mm to 507.6mm, and the tab number is (507.6 - 433.3) / 0.1 = 743. Similarly, for r = 10mm, the rb range of the tab - covering is from 10mm to 16mm, corresponding to s from 758.8mm to 2166.4mm, and the tab number is 14076.

[0039] Advantages of the 60° tab: The parallelogram-shaped tabs and 60° cutting angle allow the folded tabs to form an equilateral triangle arrangement, effectively reducing end-face unevenness. Geometrically, the 60° angle enables the tabs to support each other after folding, resulting in high stacking density and high end-face flatness, which is beneficial for current collection and battery performance.

[0040] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A calculation method for forming multiple tabs in a cylindrical battery, characterized in that, Includes the following steps: S1: Parameter settings: Taking a 58mm diameter core as an example, the specific parameters are as follows: Center hole diameter: 8mm; Positive electrode length: 7000mm, thickness: 184μm; Negative electrode length: 7200mm, thickness: 140μm; Diaphragm thickness: 12μm; Electrode gap: 0.1mm; Tab length design: Inner ring Le=4mm, middle ring=6mm, outer ring Le=4mm; S2: Electrode cutting: A die-cutting machine is used to make slit cuts in the empty foil area of ​​the positive and negative electrode sheets. The first tab of the positive electrode sheet is located 433.3 mm from the starting end, and the calculation for the negative electrode sheet is similar. S3: Winding: The cut electrode sheets and diaphragm are wound together into a core, and the electrode sheets are pre-folded by a pre-folding wheel during winding. S4: Clasp folding: After winding, the electrode tabs are formed by two gathering mechanisms and two flattening mechanisms. The electrode tabs are folded and flattened towards the end face so that the inner electrode tabs cover the edge of the center hole. S5: Stacking layer verification: The number of stacked layers on the end face is calculated using a formula. For example, at r=10mm, N=17.2 layers; at r=4mm, N=11.5 layers. The middle area with a higher number of stacked layers is the key area for welding the manifold.

2. The calculation method for forming multi-tabs in a cylindrical battery according to claim 1, characterized in that, According to S1, before winding, a die-cutting machine is used to slit the empty foil area of ​​the electrode sheet to form the electrode tab into a parallelogram shape with a cutting angle of 60°.

3. The calculation method for forming multi-tabs in a cylindrical battery according to claim 1, characterized in that, The gap between the electrodes is the diameter of the laser spot, typically 0.1 mm.

4. The calculation method for forming multiple tabs in a cylindrical battery according to claim 1, characterized in that, Both the positive and negative tabs adopt a design with a short inner ring, a long middle ring, and a short outer ring, with the tab length ranging from 4 to 6 mm.

5. The calculation method for forming multiple tabs in a cylindrical battery according to claim 1, characterized in that, The starting position for cutting the electrode tab is calculated so that the inner electrode tab is folded and flattened to cover the edge of the central hole.

6. The calculation method for forming multiple tabs in a cylindrical battery according to claim 1, characterized in that, The number of tab stacking layers at each radial position on the end face of the core is calculated using the formula N(r) = Le(r) / teff, where N(r) is the tab length at the coverage radius r, and teff is the effective winding thickness.

7. A system for implementing the method of claims 1-6, comprising a die-cutting machine, a winding machine, and a control unit, characterized in that: The die-cutting machine is configured to perform 60° parallelogram cutting, and the control unit adjusts the cutting position according to the calculated parameters.

Images