A method for flattening the full tab of a cylindrical battery

Abstract

The present invention discloses a method for flattening all tabs of a cylindrical battery, comprising the following steps: S1: The tabs are reciprocally roll-pressed by a flattening mechanism and pre-flattened to gather and pre-shape the tabs; S2: The tabs after being gathered and pre-shaped are flattened and shaped by the flattening mechanism to form regularly arranged electrolyte infiltration areas and current collector plate welding areas. In the present invention, the tabs can be gathered and pre-shaped by reciprocally roll-pressing the tabs by the flattening mechanism. While ensuring the flatness and thickness of the flattened surface, the arrangement of the tabs is optimized. The tabs after being gathered and pre-shaped are flattened and shaped by the flattening mechanism to form regularly arranged electrolyte infiltration areas and current collector plate welding areas, reducing the loss of metal chips during the flattening process, improving the short-circuit defect, and enhancing the welding qualification rate of the current collector plate and the electrolyte infiltration rate through the main function distinction of different areas of the tabs.

Description

Technical Field

[0001] The present invention relates to the technical field of flattening of cylindrical battery tabs, and more particularly to a method for flattening all tabs of a cylindrical battery. Background Art

[0002] The all-tab flattening process is a key process in the manufacturing of large cylindrical batteries. After winding, the tabs of the cylindrical battery core are flattened by flattening, and the standing tabs of the cylindrical battery core are flattened into a flat plane, so that the tabs of each layer are in close contact, and then the tabs are welded to the current collector plate at the tab ends. The thickness, tightness, and flatness of the flattened surface have a great influence on the welding effect of the current collector plate and the electrolyte infiltration efficiency. By optimizing the flattening method, the metal chips removed during flattening can be improved to a certain extent, the problems such as short circuit can be reduced, the qualified rate of current collector plate welding can be increased, and the electrolyte infiltration effect can be improved.

[0003] Currently, in the industry, for the flattening method used for flattening the tabs of all-tab battery cores, the tab texture on the tab plane after flattening is too messy, so there is a high risk of metal chips falling off the tabs during the flattening process, which may cause short circuits. Moreover, if the feed amount during the flattening process is too large, it will cause the flattened surface to be dense, affecting the electrolyte infiltration rate and the coating state of the edge of the electrode sheet; if the feed amount during the flattening process is too small, the flattened surface will be loose and not flat enough, and problems such as welding through and poor soldering are likely to occur during the welding process of the current collector plate.

[0004] The prior patent document with the publication number CN114361555A discloses a method for flattening all tabs of a cylindrical battery and an all-tab cylindrical battery. The method includes the following steps: using a first flattening wheel to rotate from the outer circle to the center of the flattened surface of the battery core to a first position; using a second flattening wheel to rotate from the center to the outer circle of the flattened surface of the battery core to a second position, and the path passed by the first flattening wheel does not overlap with the path passed by the second flattening wheel. This method can effectively increase the thickness of the flattened surface in the current collector plate welding area while reducing the thickness of the non-welding area without increasing the tab foil material, improve the yield rate of current collector plate welding, and improve the electrolyte infiltration rate, and at the same time solve the problem of the flattened surface blocking the center hole.

[0005] However, this device still has the following problems:

[0006] 1. During the process of the second flattening wheel flattening from the center of the battery core to the outside, the tabs will be torn, and it is more likely to have chips falling off, resulting in an increase in short circuit defects;

[0007] 2. The outer tabs flattened by the first flattening wheel have no significant difference from the traditional flattened outer circle, and the thickness reduction of the non-welding area and the infiltration efficiency improvement are limited;

[0008] 3. The tab thickening area is annularly distributed on the end face of the battery core, the welding marks are distributed on a section of the electrode sheet close to the middle of the wound core, the current passing through the outer and inner electrode sheets of the battery core is reduced, and the thickness distribution uniformity fluctuates greatly, and the welding effect is difficult to control. Summary of the Invention

[0009] The technical problem to be solved by the present invention is how to optimize the morphology of the tab after ironing, improve the qualified rate of the current collector plate welding, and enhance the electrolyte infiltration efficiency.

[0010] The present invention solves the above technical problems through the following technical means: a method for ironing all tabs of a cylindrical battery, comprising the following steps:

[0011] S1: The tab is reciprocally roll-pressed by an ironing mechanism and pre-ironed to gather and pre-shape the tab;

[0012] S2: The ironing mechanism irones and shapes the gathered and pre-shaped tab to form regularly arranged electrolyte infiltration areas and current collector plate welding areas.

[0013] By reciprocally roll-pressing the tab with the ironing mechanism, the tab can be gathered and pre-shaped. While ensuring the flatness and thickness of the ironing surface, the arrangement of the tabs is optimized. By ironing and shaping the gathered and pre-shaped tab with the ironing mechanism to form regularly arranged electrolyte infiltration areas and current collector plate welding areas, the dropping of metal chips during the ironing process is reduced, the short-circuit defect is improved, and through the main function differentiation of different areas of the tab, the qualified rate of the current collector plate welding and the electrolyte infiltration rate are improved.

[0014] As a preferred technical solution, the reciprocating roll-pressing in step S1 includes the following steps:

[0015] S1-1: The ironing mechanism rotates clockwise from the starting position on the ironing surface of the battery cell to pre-shape the tab and reaches the first position;

[0016] S1-2: The ironing mechanism rotates counterclockwise from the first position and reaches the second position;

[0017] S1-3: The ironing mechanism rotates clockwise from the second position and returns to the first position.

[0018] Through the above three steps, the tab can form a flat, regularly arranged electrolyte infiltration area of the tab and a current collector plate welding area with double-layer overlapping of the tab, reduce the dropping of metal chips, reduce the risk of short circuit defects in the battery cell, and the orderly stacked infiltration area can allow the electrolyte to enter at a faster speed, improving the electrolyte infiltration rate; and after ironing the gathered area formed by gathering and shaping, the tab forms a current collector plate welding area with double-layer overlapping, which can obtain a larger welding process window and has a significant improvement effect on the defects of the current collector plate being welded through or having false soldering.

[0019] As a preferred technical solution, in step S2, the ironing mechanism starts rotating from the second position and stops after forming regularly arranged electrolyte infiltration areas of the tab and a current collector plate welding area with double-layer overlapping of the tab that can be distinguished according to the tab morphology.

[0020] As a preferred technical solution, the flattening mechanism is a multi-wheel flattening roller assembly. The multi-wheel conical flattening roller assembly includes a plurality of flattening rollers. The plurality of flattening rollers are arranged on the pre-flattening side of the battery cell and are equally angularly distributed around the vertical projection of the axis of the battery cell.

[0021] As a preferred technical solution, when the number of the flattening rollers is four, the rotation angle in the step S1-1 is 45°, and the rotation angles in the steps S1-2 and S1-3 are both 90°.

[0022] As a preferred technical solution, when the number of the flattening rollers is three, the rotation angle in the step S1-1 is 60°, and the rotation angles in the steps S1-2 and S1-3 are both 105°.

[0023] As a preferred technical solution, the flattening rollers are conical rollers. The conical vertices of the plurality of flattening rollers face the axis of the battery cell, and the extension lines of their axes can intersect at one point.

[0024] As a preferred technical solution, the central axes of the plurality of flattening rollers are all inclined towards the center of the battery cell.

[0025] As a preferred technical solution, the gathering pre-shaping in the step S1 is performed multiple times. By performing the gathering pre-shaping multiple times, the final shaping effect can be improved.

[0026] As a preferred technical solution, the feed amounts of the rotation of the flattening mechanism in the steps S1-1, S1-2, and S1-3 are the same.

[0027] The advantages of the present invention are as follows:

[0028] (1) In the present invention, the ear can be gathered and pre-shaped by reciprocating rolling of the ear by the flattening mechanism. While ensuring the flatness and thickness of the flattened surface, the arrangement of the ears is optimized. The ears after gathering and pre-shaping are flattened and shaped by the flattening mechanism to form a regularly arranged electrolyte infiltration area and a current collector welding area, reducing metal chips dropping during the flattening process, improving the short-circuit defect, and enhancing the current collector welding qualification rate and electrolyte infiltration rate through the main function distinction of different regions of the ear.

[0029] (2) In the present invention, through the above three steps, the ears can form a flat, regularly arranged electrolyte infiltration area of the ears and a current collector welding area with double-layer overlapping of the ears, reducing the dropping of metal chips, reducing the risk of short circuit defect of the battery cell, and the orderly stacked infiltration area can allow the electrolyte to enter at a faster speed, enhancing the electrolyte infiltration rate; and after flattening the gathering area formed by gathering and shaping, the ears form a current collector welding area with double-layer overlapping, and a larger welding process window can be obtained, which has a significant improvement effect on the defects of current collector welding through or poor soldering. Description of the Drawings

[0030] Figure 1 Schematic flow diagram of step S1 of a method for flattening all tab ears of a cylindrical battery provided by an embodiment of the present invention;

[0031] Figure 2 Schematic diagram of the cell structure of a method for flattening all tab ears of a cylindrical battery provided by an embodiment of the present invention;

[0032] Figure 3 Schematic diagram of the structure of the tab ear after pre - shaping in a method for flattening all tab ears of a cylindrical battery provided by an embodiment of the present invention;

[0033] Figure 4 Schematic diagram of the structure of the tab ear after flattening in a method for flattening all tab ears of a cylindrical battery provided by an embodiment of the present invention;

[0034] Reference numerals: 1, flattening mechanism; 2, cell; 3, tab ear. Detailed implementation manners

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0036] Refer to Figure 1 , a method for flattening all tab ears of a cylindrical battery, including the following steps:

[0037] S1: The flattening mechanism 1 performs reciprocating rolling on the tab ear 3 at a fixed angle and pre - flattens it to gather and pre - shape the tab ear 3, which can be performed multiple times according to the actual gathering and shaping effect;

[0038] S1 - 1: The flattening mechanism 1 rotates clockwise from the starting position on the flattening plane of the cell 2 to pre - shape the tab ear 3 and reaches the first position; the flattening plane of the cell is the plane at the top of the cell 2 where the tab ear 3 is provided;

[0039] S1 - 2: The flattening mechanism 1 rotates counterclockwise from the first position and reaches the second position;

[0040] S1 - 3: The flattening mechanism 1 rotates clockwise from the second position and returns to the first position;

[0041] S2: The leveling mechanism 1 levels and shapes the gathered and pre-shaped tab 3 to form a regularly arranged electrolyte infiltration area and a current collector welding area. The leveling mechanism 1 starts rotating from the second position and stops after forming a regularly arranged electrolyte infiltration area of the tab 3 that can be distinguished according to the morphology of the tab 3 and a current collector welding area with double-layer overlapping tabs 3, thereby forming a current collector welding area with double-layer overlapping and a regularly arranged electrolyte infiltration area.

[0042] Among them, the leveling mechanism 1 includes a multi-wheel leveling roller assembly. The multi-wheel conical leveling roller assembly includes multiple leveling rollers. The multiple leveling rollers are arranged on the pre-leveling side of the battery cell 2 and are equally angularly distributed with the vertical projection of the axis of the battery cell 2 as the center. The leveling rollers are conical rollers. The conical vertices of the multiple leveling rollers face the axis of the battery cell 2, and the extension lines of their axes can intersect at a point on the axis of the battery cell 2. Among them, the leveling rollers are inclined. In this embodiment, taking four leveling rollers as an example, the rotation angle in S1-1 is 45°, and the rotation angles in step S1-2 and step S1-3 are both 90°.

[0043] Refer to Figures 1 to 4 , and the usage method is specifically as follows:

[0044] Step 1: The leveling mechanism 1 rotates 45° clockwise from the starting position on the leveling plane of the battery cell 2 at a certain feed rate to pre-shape the tab 3 and reaches the first position;

[0045] Step 2: The leveling mechanism 1 rotates 90° counterclockwise from the first position at the same feed rate and reaches the second position;

[0046] Step 3: The leveling mechanism 1 rotates 90° clockwise from the second position at the same feed rate and returns to the first position;

[0047] Steps 2 and 3 are repeated twice to achieve the best shaping and gathering effect of the tab 3;

[0048] Step 4: The leveling mechanism 1 starts rotating 20 circles from the second position to perform the final leveling and shaping of the tab 3;

[0049] Step 5: The above-leveled battery cell 2 is subjected to current collector welding, and the welding track position is adjusted to the flattened position after the tabs 3 are gathered; the battery cell 2 after current collector welding is subjected to a hipot (breakdown voltage) test to confirm the change in its infiltration efficiency and short-circuit rate;

[0050] The test results are as follows: After leveling the battery cell, the appearance of the tab leveling plane is confirmed to be flat, and the arrangement of the tabs 3 is clear; the hipot failure rate after leveling is 0.07%; the current collector welding power window can be appropriately increased without causing welding penetration, and the current collector welding penetration is about 0.04%.

[0051] Embodiment 2

[0052] Referring to Figures 2 to 4 , the difference between this embodiment and Embodiment 1 is that the number of flattening rollers is different. In this Embodiment 2, taking three as an example, in order to obtain the best gathering and shaping effect of the tab 2, the rotation angle can be appropriately adjusted according to the number of rollers. The rotation angle in step S1-1 is 60°, and the rotation angles in step S1-2 and step S1-3 are both 105°.

[0053] The specific usage method is as follows:

[0054] Step 1: The flattening mechanism 1 rotates 60° clockwise from the starting position at a certain feed rate on the flattened surface of the battery cell 2 to pre-shape the tab 3 and reaches the first position;

[0055] Step 2: The flattening mechanism 1 rotates 105° counterclockwise from the first position at the same feed rate and reaches the second position;

[0056] Step 3: The flattening mechanism 1 rotates 105° clockwise from the second position at the same feed rate and returns to the first position;

[0057] Steps 2 and 3 are repeated twice to achieve the best shaping and gathering effect of the tab 3;

[0058] Step 4: The flattening mechanism 1 rotates 20 circles starting from the second position to finally flatten and shape the tab 3;

[0059] Step 5: Weld the current collector plate to the flattened battery cell 2 above, and adjust the welding track position to the flattened area after the tabs 3 are gathered; perform a hipot (breakdown voltage) test on the battery cell 2 after the current collector plate welding is completed to confirm the change in its infiltration efficiency and short-circuit rate.

[0060] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for flattening the full tab of a cylindrical battery, comprising the following steps: S1: The tab is reciprocally roll-pressed and pre-smoothed by a smoothing mechanism to gather and pre-shape the tab. The feature is that the smoothing mechanism is a multi-wheel smoothing roller assembly, and the smoothing mechanism includes a plurality of conical rollers; the reciprocal roll-pressing includes: S1-1: The smoothing mechanism rotates clockwise from the starting position on the smoothing plane of the battery cell to pre-shape the tab and reaches the first position; S1-2: The smoothing mechanism rotates counterclockwise from the first position and reaches the second position; S1-3: The smoothing mechanism rotates clockwise from the second position and returns to the first position; S2: The tab after being gathered and pre-shaped is smoothed and shaped by the smoothing mechanism to form a regularly arranged electrolyte infiltration area and a current collector welding area with double-layer overlapping tabs. The current collector welding area protrudes relative to the electrolyte infiltration area.

2. The method for flattening the full tab of a cylindrical battery according to claim 1, wherein In step S2, the smoothing mechanism starts to rotate from the second position and stops after forming a regularly arranged electrolyte infiltration area of the tab that can be distinguished according to the tab morphology and a current collector welding area with double-layer overlapping tabs.

3. The method for flattening the full tab of a cylindrical battery according to claim 1, wherein The multi-wheel smoothing roller assembly includes a plurality of smoothing rollers. The plurality of smoothing rollers are arranged on the pre-smoothed side of the battery cell and are equally angularly distributed with the vertical projection of the battery cell axis as the center.

4. The method for flattening the full tab of a cylindrical battery according to claim 3, wherein When the number of the smoothing rollers is four, the rotation angle in step S1-1 is 45°, and the rotation angles in step S1-2 and step S1-3 are both 90°.

5. The method for flattening the full tab of a cylindrical battery according to claim 3, wherein When the number of the smoothing rollers is three, the rotation angle in step S1-1 is 60°, and the rotation angles in step S1-2 and step S1-3 are both 105°.

6. The method for flattening the full tab of a cylindrical battery according to claim 3, wherein The conical vertices of the plurality of smoothing rollers face the battery cell axis, and the extension lines of their axes intersect at one point.

7. The method for flattening the full tab of a cylindrical battery according to claim 6, wherein The central axes of the plurality of smoothing rollers are all inclined towards the center of the battery cell.

8. The method for flattening the full tab of a cylindrical battery according to claim 1, wherein The gathering and pre-shaping in step S1 is performed multiple times.

9. The method for flattening the full tab of a cylindrical battery according to claim 1, wherein The feed amounts of the rotation of the smoothing mechanism in step S1-1, step S1-2, and step S1-3 are the same.

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