Calculation method for die cutting tab spacing of sodium ion battery cell

Abstract

The invention discloses a method for calculating the distance between die-cutting tabs of a sodium ion battery cell. The method comprises the following steps: S1, calculating the length of a pre-winding diaphragm; s2, calculating the perimeter of the winding core after the diaphragm is pre-wound; s3, calculating the winding length of the first circle of negative pole piece; s4, calculating the perimeter of the winding core after the first circle of negative pole piece is wound; s5, calculating the winding length of the first circle of positive pole piece; s6, calculating the perimeter of a roll core after the first circle of positive pole piece is wound; s7, calculating the winding length of the second circle of negative pole piece and the perimeter of the wound core; s8, calculating the winding length of the second circle of positive pole piece and the perimeter of the wound core; s9, calculating the winding length of the (n-1) th circle of negative pole piece and the perimeter of the wound core; according to the method, the calculation accuracy can be improved, the trial production intensity of die cutting and winding after the cell process is changed can be reduced, the phenomenon of tab dislocation can be obviously reduced, and meanwhile, reasons can be quickly analyzed and found out and die cutting and winding parameters can be adjusted according to the tab dislocation condition.

Description

Technical Field

[0001] The invention relates to the technical field of sodium ion battery core winding, and in particular to a method for calculating the spacing between die-cut tabs of a sodium ion battery core. Background Art

[0002] Battery tabs are key components (copper or aluminum) that lead out the positive and negative electrodes inside the battery and connect them to other batteries or external devices, playing the role of switching and power transmission. Battery tab size and tab spacing are important characteristic parameters of battery products. In the battery manufacturing process, the measurement of battery tab size and tab spacing is an important process. If the battery tab size and tab spacing exceed the design requirements, it will cause the tabs to be misaligned after the module is stacked, which will lead to welding defects and the product cannot meet the use requirements. Therefore, it is necessary to calculate the tab spacing of the sodium ion battery die-cutting.

[0003] Traditionally, the calculation of the spacing between the die-cut tabs of sodium-ion battery cells is usually that the positive and negative electrodes are simultaneously calculated based on the circumference of the battery cell after the second outer positive (or negative) electrode sheet is wound. For example, the positive and negative electrodes are simultaneously calculated based on the circumference of the battery cell after the second outer positive electrode sheet is wound, and the electrode sheets are arranged in a positive-negative-positive manner. During the calculation, since the winding arc is the same, but the core radius increments of the negative and positive electrodes are different, the increments of their arc lengths are also different. If the arc length increment of the negative electrode is the same as that of the positive electrode at this time, since the winding radius of the negative electrode is smaller than that of the positive electrode, the winding arc of the negative electrode sheet is larger than that of the positive electrode sheet, which easily causes the tabs to be misaligned. In addition, when traditionally calculating the increment of the battery cell with incompletely wound electrode sheets, the calculation is based on the change in the circumference of the winding needle after the winding needle is affixed with Teflon, and the calculation accuracy is low. Therefore, we propose a method for calculating the spacing between the die-cut tabs of sodium-ion battery cells. Summary of the invention

[0004] The purpose of the present invention is to provide a method for calculating the spacing between die-cut tabs of a sodium ion battery cell to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for calculating the spacing between die-cut tabs of a sodium ion battery cell, comprising the following steps:

[0006] S1. Let R be the length of the diaphragm (mm), and the length of each winding section is represented by R0, R1, R2, ... R n+2 Indicates that the length of the pre-wound diaphragm is calculated using the formula:

[0007] R0=2π×(F / 2π)×N=NF (1);

[0008] Among them, F is the actual winding needle circumference, and N is the number of pre-winding turns;

[0009] S2. Calculate the circumference of the winding core after pre-winding the separator: Let U be the circumference of the winding core at different stages as the number of positive and negative electrode sheets increases (mm), and use U0, U1...U n+2 Indicates the core circumference of a single roll of a non-polar diaphragm (mm), expressed in U 负1 , U 负2 ...U 负n , U 负n+1 Indicates the circumference of the winding core at each stage of the negative electrode sheet (mm), expressed in U 正1 , U 正2 ...U 正n Indicates the circumference of the core when each stage of winding of the positive electrode is completed (mm), the formula is:

[0010] U0=F+N×2×2π×E0=F+4NπE0 (2)

[0011] Among them, F is the actual winding needle circumference after the winding core is attached with Teflon, and E0 is the thickness of the diaphragm;

[0012] S3. Calculate the winding length of the first negative electrode sheet (the first parameter of negative electrode die cutting) using the formula:

[0013] S1=U0+2π×E0-L-((AJ) / 2-B / 2)=U0+2π×E0-L-(KB / 2) (3);

[0014] Among them, 2π×E0 is the difference in the circumference of the winding core caused by the inner separator covering the negative electrode, L is the length of the negative electrode sheet insertion position, A is the width of the battery cell, J is the center distance of the tabs, B is the thickness of the battery cell, and K is the negative tab margin (the distance from the center of the negative tab to the edge of the battery cell after hot pressing);

[0015] S4. Calculate the circumference of the winding core after the first circle of negative electrode sheet is wound. The formula is:

[0016] U 负1 =U0+2π×(C+E0)×S1 / (U0+2π×(C+E0))≈U0+2πaH×S1 / (U0+2πaH) (4);

[0017] Wherein, C is the thickness of the negative electrode sheet, H is the change in the thickness of the winding core when the positive electrode sheet and the separator are wound for one cycle (mm), and a is the winding correction coefficient of the negative electrode sheet;

[0018] S5. Calculate the winding length of the first positive electrode sheet (the first parameter of positive electrode die cutting) using the formula:

[0019] T1=U 负1 +2π×(D+E)-MJ=U 负1 +2πbH-MJ (5);

[0020] Wherein, D is the thickness of the positive electrode sheet, M is the positive electrode insertion position value (mm), J is the center distance between the positive and negative electrode tabs of a single cell (mm), and b is the positive electrode sheet winding correction coefficient;

[0021] S6. Calculate the circumference of the winding core after the first circle of positive electrode sheet is wound. The formula is:

[0022] U 正1 =U 负1 +2π×(D+E)×T1 / (U 负1 +2π×(D+E))=U 负1 +2πbH×T1 / (U 负1 +2πbH) (6);

[0023] S7. Calculate the winding length of the second negative electrode sheet (the second parameter of negative electrode die cutting) and the circumference of the winding core after winding. The formula is:

[0024] U 负2 =S2=U 正1 +2π×(C+E)=U 正1 +2πaH (7);

[0025] S8. Calculate the winding length of the second positive electrode sheet (the second parameter of positive electrode die cutting) and the circumference of the winding core after winding. The formula is:

[0026] U 正2 =T2=U 负2 +2π×(D+E)=U 负2 +2πbH (8);

[0027] ……;

[0028] S9. Calculate the winding length of the n-1th negative electrode sheet (the n-1th parameter of the negative electrode die cutting) and the circumference of the winding core after winding. The formula is:

[0029] U 负n-1 =S n-1 =U 正n-2 +2π×(C+E)=U 正n-2 +2πaH (9);

[0030] S10. Calculate the winding length of the positive electrode sheet of the n-1th circle (the n-1th parameter of the positive electrode die cutting) and the circumference of the winding core after winding. The formula is:

[0031] U 正n-1 =T n-1 =U 负n-1 +2π×(D+E)=U 负n-1 +2πbH (10).

[0032] Preferably, the method further includes S11, calculating the winding length of the n-th negative electrode sheet (the n-th parameter of the negative electrode die cutting) and the circumference of the winding core after winding, and the formula is:

[0033] U 负n =S n =U 正n-1 +2π×(C+E)=U 正n-1 +2πaH (11);

[0034] S12. Calculate the winding length of the nth positive electrode sheet (the nth parameter of positive electrode die cutting), the formula is:

[0035] T n =(U 负n +2π×(D+E))×P=U 负n P+2πbHP(12), where P is the number of positive electrode closing turns;

[0036] S13. Calculate the circumference of the winding core after the nth round of positive electrode sheet is wound. The formula is:

[0037] U 正n =U 负n +2π×(D+E)×P=U 正n-2 +2πbHP (13);

[0038] S14, calculate the winding length of the negative electrode sheet of the n+1th circle (the n+1th parameter of the negative electrode die cutting), the formula is:

[0039] S n+1 =(U 正n +2π×(C+E))×Q=U 正n P + 2πaHP (14), where Q is the number of negative terminal closing turns;

[0040] S15. Calculate the circumference of the winding core after the n+1th winding of the negative electrode sheet. The formula is:

[0041] U 正n+1 =U 正n +2π×(C+E)×Q=U 正n +2πaHP (15);

[0042] S16. Calculate the winding length of the n+2th circle of the separator (the n+1th parameter of the negative electrode die cutting), the formula is:

[0043] R n+2 =(U 正n+1 +2×2πE0)×O=U 正n+1 O+4πE0O(16), where O is the number of diaphragm closing turns;

[0044] S17, calculate the circumference of the core after the n+2th circle of diaphragm is wound, the formula is:

[0045] U n+2 =U 正n+1 +2×2πE0×O=U 正n+1 +4πE0O ​​(17).

[0046] Preferably, starting from the negative electrode tab, winding the pole sheet or separator once back to the center of the negative electrode tab is considered as one circle.

[0047] Preferably, when the electrode sheet is not fully wound and wound, the cell increment of the electrode sheet that is not fully wound needs to be calculated, and the formula is:

[0048]

[0049] Preferably, when the electrode sheet is fully rolled, the increment of the negative electrode sheet die-cutting parameters is based on the circumference of the winding core after the second outer layer positive electrode sheet is wound. Similarly, the increment of the positive electrode sheet die-cutting parameters is based on the circumference of the winding core after the second outer layer negative electrode sheet is wound.

[0050] Preferably, a negative electrode pole sheet winding correction coefficient a and a positive electrode pole sheet winding correction coefficient b=1-a are established. When calculated for the first time, a=(C+E1+2E2) / (C+D+2E1+4E2), wherein C is the thickness of the negative electrode pole sheet, D is the thickness of the positive electrode pole sheet, E1 is the thickness of the diaphragm, and E2 is the distance between the diaphragm and the pole sheet. The values ​​of a and b are corrected in actual production according to the pole sheet winding performance.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] 1. In the present invention, except for the cases of electrode sheet winding and finishing, when the electrode sheet is fully wound, the increment of the die-cutting parameters of the negative electrode sheet is based on the circumference of the core after the second outer layer positive electrode sheet is wound. Similarly, the increment of the die-cutting parameters of the positive electrode sheet is based on the circumference of the core after the second outer layer negative electrode sheet is wound. This calculation method has higher accuracy than calculating the circumference of the battery cell after the second outer layer positive (or negative) electrode sheet is wound at the same time. It can improve the calculation accuracy and reduce the trial production intensity of die-cutting and winding after the battery cell process is changed.

[0053] 2. The present invention can significantly reduce the phenomenon of tab misalignment. At the same time, the cause can be quickly analyzed and found out according to the tab misalignment, and the die-cutting and winding parameters can be adjusted. DETAILED DESCRIPTION

[0054] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0055] The present invention provides a technical solution: a method for calculating the spacing between die-cut tabs of a sodium ion battery cell, comprising the following steps:

[0056] S1. Let R be the length of the diaphragm (mm), and the length of each winding section is represented by R0, R1, R2, ... R n+2 Indicates that the length of the pre-wound diaphragm is calculated using the formula:

[0057] R0=2π×(F / 2π)×N=NF (1);

[0058] Among them, F is the actual winding needle circumference, and N is the number of pre-winding turns;

[0059] S2. Calculate the circumference of the winding core after pre-winding the separator: Let U be the circumference of the winding core at different stages as the number of positive and negative electrode sheets increases (mm), and use U0, U1...U n+2 Indicates the core circumference of a single roll of a non-polar diaphragm (mm), expressed in U 负1 , U 负2 ...U 负n , U 负n+1 Indicates the circumference of the winding core at each stage of the negative electrode sheet (mm), expressed in U 正1 , U 正2 ...U 正n Indicates the circumference of the core when each stage of winding of the positive electrode is completed (mm), the formula is:

[0060] U0=F+N×2×2π×E0=F+4NπE0 (2)

[0061] Among them, F is the actual winding needle circumference after the winding core is attached with Teflon, and E0 is the thickness of the diaphragm;

[0062] S3. Calculate the winding length of the first negative electrode sheet (the first parameter of negative electrode die cutting) using the formula:

[0063] S1=U0+2π×E0-L-((AJ) / 2-B / 2)=U0+2π×E0-L-(KB / 2) (3);

[0064] Among them, 2π×E0 is the difference in the circumference of the winding core caused by the inner separator covering the negative electrode, L is the length of the negative electrode sheet insertion position, A is the width of the battery cell, J is the center distance of the tabs, B is the thickness of the battery cell, and K is the negative tab margin (the distance from the center of the negative tab to the edge of the battery cell after hot pressing);

[0065] S4. Calculate the circumference of the winding core after the first circle of negative electrode sheet is wound. The formula is:

[0066] U 负1=U0+2π×(C+E0)×S1 / (U0+2π×(C+E0))≈U0+2πaH×S1 / (U0+2πaH) (4);

[0067] Wherein, C is the thickness of the negative electrode sheet, H is the change in the thickness of the winding core when the positive electrode sheet and the separator are wound for one cycle (mm), and a is the winding correction coefficient of the negative electrode sheet;

[0068] S5. Calculate the winding length of the first positive electrode sheet (the first parameter of positive electrode die cutting) using the formula:

[0069] T1=U 负1 +2π×(D+E)-MJ=U 负1 +2πbH-MJ (5);

[0070] Wherein, D is the thickness of the positive electrode sheet, M is the positive electrode insertion position value (mm), J is the center distance between the positive and negative electrode tabs of a single cell (mm), and b is the positive electrode sheet winding correction factor;

[0071] S6. Calculate the circumference of the winding core after the first circle of positive electrode sheet is wound. The formula is:

[0072] U 正1 =U 负1 +2π×(D+E)×T1 / (U 负1 +2π×(D+E))=U 负1 +2πbH×T1 / (U 负1 +2πbH) (6);

[0073] S7. Calculate the winding length of the second negative electrode sheet (the second parameter of negative electrode die cutting) and the circumference of the winding core after winding. The formula is:

[0074] U 负2 =S2=U 正1 +2π×(C+E)=U 正1 +2πaH (7);

[0075] S8. Calculate the winding length of the second positive electrode sheet (the second parameter of positive electrode die cutting) and the circumference of the winding core after winding. The formula is:

[0076] U 正2 =T2=U 负2 +2π×(D+E)=U 负2 +2πbH (8);

[0077] ……;

[0078] S9. Calculate the winding length of the n-1th negative electrode sheet (the n-1th parameter of the negative electrode die cutting) and the circumference of the winding core after winding. The formula is:

[0079] U负n-1 =S n-1 =U 正n-2 +2π×(C+E)=U 正n-2 +2πaH (9);

[0080] S10. Calculate the winding length of the positive electrode sheet of the n-1th circle (the n-1th parameter of the positive electrode die cutting) and the circumference of the winding core after winding. The formula is:

[0081] U 正n-1 =T n-1 =U 负n-1 +2π×(D+E)=U 负n-1 +2πbH (10).

[0082] S11. Calculate the winding length of the nth negative electrode sheet (the nth parameter of negative electrode die cutting) and the circumference of the winding core after winding. The formula is:

[0083] U 负n =S n =U 正n-1 +2π×(C+E)=U 正n-1 +2πaH (11);

[0084] S12. Calculate the winding length of the nth positive electrode sheet (the nth parameter of positive electrode die cutting), the formula is:

[0085] T n =(U 负n +2π×(D+E))×P=U 负n P+2πbHP(12), where P is the number of positive electrode closing turns;

[0086] S13. Calculate the circumference of the winding core after the nth round of positive electrode sheet is wound. The formula is:

[0087] U 正n =U 负n +2π×(D+E)×P=U 正n-2 +2πbHP (13);

[0088] S14, calculate the winding length of the negative electrode sheet of the n+1th circle (the n+1th parameter of the negative electrode die cutting), the formula is:

[0089] S n+1 =(U 正n +2π×(C+E))×Q=U 正n P + 2πaHP (14), where Q is the number of negative terminal closing turns;

[0090] S15. Calculate the circumference of the winding core after the n+1th winding of the negative electrode sheet. The formula is:

[0091] U 正n+1 =U正n +2π×(C+E)×Q=U 正n +2πaHP (15);

[0092] S16. Calculate the winding length of the n+2th circle of the separator (the n+1th parameter of the negative electrode die cutting), the formula is:

[0093] R n+2 =(U 正n+1 +2×2πE0)×O=U 正n+1 O+4πE0O(16), where O is the number of diaphragm closing turns;

[0094] S17, calculate the circumference of the core after the n+2th circle of diaphragm is wound, the formula is:

[0095] U n+2 =U 正n+1 +2×2πE0×O=U 正n+1 +4πE0O ​​(17).

[0096] Among them, A is the width of a single cell (mm), B is the thickness of a single cell (mm), C is the thickness of the negative electrode sheet (mm), D is the thickness of the positive electrode sheet (mm), E1 is the thickness of the diaphragm (mm), E2 is the distance between the diaphragm and the electrode sheet (or the diaphragm and the diaphragm) (mm), E0=E1+E2 is the thickness of the diaphragm when the diaphragm without the electrode sheet is rolled alone (mm), E=E1+2E2 is the thickness of the diaphragm when the positive (negative) electrode sheet and the diaphragm are rolled together = Degree (mm), F1 is the circumference of the bare winding needle (mm), F2 is the change in the circumference of the winding needle after the winding needle is affixed with Teflon (mm), F = F1 + F2 is the actual circumference of the winding needle (mm), G = (C + D + 2E) is the change in the thickness of the winding core when the positive electrode sheet, the negative electrode sheet and the separator are wound for one cycle (mm), H = a × G is the change in the thickness of the winding core when the positive electrode sheet and the separator are wound for one cycle (mm), a is the correction factor, The inner negative electrode sheet and the outer positive electrode sheet have the same curvature, but different radii and arc length increments. In the first calculation, a=(C+E) / H can be used for estimation. I=b×G is the change in core thickness when the negative electrode sheet and the separator are wound for one circle (mm). b is the correction factor. Because the inner positive electrode sheet and the outer negative electrode sheet have the same curvature, but different radii and arc length increments, b=1-a can be used for calculation. In practical applications, the values ​​of a and b are corrected according to the actual test values. J is the center distance of the pole ear (mm), K=(AJ) / 2 is the edge distance of the pole ear (mm), L is the negative electrode insertion position value (mm), M is the positive electrode insertion position value (mm), N is the number of pre-winding turns of the separator, O is the number of closing turns of the separator, P is the number of closing turns of the positive electrode, Q is the number of closing turns of the negative electrode, R is the length of the separator (mm), and the length of each winding section is represented by R0, R1, R2...R n+2 Indicated by, S is the length of the negative electrode sheet, and the length of each winding section is S1, S2...Sn Indicated by, T is the length of the positive electrode sheet, and the length of each winding section is T1, T2...T n Indicates that U is the core circumference value (mm) at different stages as the number of positive and negative electrode winding layers increases, represented by U0, U1, ... U n+2 Indicates the core circumference of a single roll of a non-polar diaphragm (mm), expressed in U 负1 , U 负2 ...U 负n , U 负n+1 Indicates the circumference of the winding core at each stage of the negative electrode sheet (mm), expressed in U 正1 , U 正2 ...U 正n Indicates the circumference of the winding core (mm) when each stage of the positive electrode winding is completed.

[0097] It should be noted that when the pole piece is wound and wound up for less than one circle, the formula

[0098]

[0099] Calculate the increment of the battery cell of the incompletely wound electrode sheet. This calculation method is simpler and more practical than the Archimedean spiral calculation formula, and the calculation accuracy is much higher than the die-cutting accuracy of existing die-cutting equipment, and is also much higher than the accuracy of the change in the circumference of the existing winding needle after the Teflon is added to the winding needle, which can meet the existing sodium battery production needs; except for the electrode sheet rolling and finishing, when the electrode sheet is fully wound, the increment of the negative electrode sheet die-cutting parameters is based on the circumference of the winding core after the second outer layer positive electrode sheet is wound. Similarly, the increment of the positive electrode sheet die-cutting parameters is based on the circumference of the winding core after the second outer layer negative electrode sheet is wound. This calculation method has higher accuracy than the calculation of the circumference of the battery cell when the positive and negative electrodes are simultaneously based on the second outer layer positive (or negative) electrode sheet. In addition to the different thicknesses of the above-mentioned positive and negative electrodes, In addition to affecting the calculation of die-cutting parameters, the positive and negative pole sheets have different tension coefficients after rolling due to the different materials. Due to the existence of tension during die-cutting and winding, the pole sheets have different elongation amounts. At the same time, the thickness changes of the pole sheets when the pole sheets are bent are also different. Therefore, a negative pole sheet winding correction coefficient a and a positive pole sheet winding correction coefficient b=1-a are established. When calculating for the first time, a=(C+E1+2E2) / (C+D+2E1+4E2), where C is the thickness of the negative pole sheet, D is the thickness of the positive pole sheet, E1 is the thickness of the diaphragm, and E2 is the distance between the diaphragm and the pole sheet (or between the diaphragm and the diaphragm). The values ​​of a and b need to be corrected in actual production according to the pole sheet winding performance.

[0100] In addition, the terms "first", "second", "third" and "fourth" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first", "second", "third" and "fourth" may explicitly or implicitly include at least one of such features.

[0101] In the present invention, unless otherwise clearly stipulated and limited, the terms such as "installation", "setting", "connection", "fixation" and "screw-on" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. Unless otherwise clearly defined, ordinary technicians in this field can understand the specific meanings of the above terms in the present invention according to the specific circumstances.

[0102] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for calculating the distance between die-cut tabs of sodium ion batteries, characterized in that: The steps include: S1. Calculate the length of the pre-wound diaphragm; S2, calculate the circumference of the winding core after the pre-wound diaphragm; S3, calculating the winding length of the first circle of the negative electrode sheet; S4, calculating the circumference of the winding core after the first circle of the negative electrode sheet is wound; S5, calculating the winding length of the first circle of the positive electrode sheet; S6, calculating the circumference of the winding core after the first circle of the positive electrode sheet is wound; S7, calculating the winding length of the second turn of the negative electrode sheet and the circumference of the winding core after winding; S8, calculating the winding length of the second positive electrode sheet and the circumference of the winding core after winding; S9, calculating the winding length of the negative electrode sheet of the n-1th turn and the circumference of the winding core after winding; S10, calculate the winding length of the n-1th positive electrode sheet (the n-1th parameter of the positive electrode die-cutting) and the circumference of the winding core after winding.

2. The method for calculating the distance between die-cut tabs of a sodium ion battery cell according to claim 1, characterized in that: The method further includes S11, calculating the winding length of the n-th negative electrode sheet and the circumference of the winding core after winding; S12, calculating the winding length of the nth positive electrode sheet; S13, calculating the circumference of the winding core after the nth round of positive electrode sheet is wound; S14, calculating the winding length of the negative electrode sheet of the n+1th turn; S15, calculating the circumference of the winding core after the (n+1)th winding of the negative electrode sheet; S16, calculating the winding length of the n+2th diaphragm circle; S17, calculating the circumference of the winding core after the n+2th circle of diaphragm is wound.

3. The method for calculating the distance between die-cut tabs of a sodium ion battery cell according to claim 1, characterized in that: Starting from the negative electrode tab, one circle is considered as one circle when the pole piece or separator is wound back to the center of the negative electrode tab.

4. The method for calculating the distance between die-cut tabs of a sodium ion battery cell according to claim 1, characterized in that: When the pole piece is wound in and out for less than one circle, the formula is used: Calculate the increment of the battery cell with incompletely wound pole pieces.

5. The method for calculating the distance between die-cut tabs of a sodium ion battery cell according to claim 1, characterized in that: When the electrode sheet is fully wound, the increment of the negative electrode sheet die-cutting parameters is based on the circumference of the core after the second outer positive electrode sheet is wound. Similarly, the increment of the positive electrode sheet die-cutting parameters is based on the circumference of the core after the second outer negative electrode sheet is wound.

6. The method for calculating the distance between die-cut tabs of a sodium ion battery cell according to claim 1, characterized in that: Establish the negative electrode sheet winding correction coefficient a, the positive electrode sheet winding correction coefficient b = 1-a. When calculating for the first time, a = (C + E1 + 2E2) / (C + D + 2E1 + 4E2), where C is the thickness of the negative electrode sheet, D is the thickness of the positive electrode sheet, E1 is the thickness of the diaphragm, and E2 is the distance between the diaphragm and the electrode sheet. The values ​​of a and b are corrected in actual production according to the electrode sheet winding performance.

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