A method for manufacturing a multi-pole tab cell pole piece

Abstract

The application belongs to the technical field of secondary batteries. More particularly, it relates to a preparation method of a multi-tab cell pole piece. The specific preparation steps of the application include: providing a cell pole piece, the cell pole piece comprising a current collector, a coating area of an active material region coated on the current collector, and a blank area on one side of the coating area, which is not coated with the active material region; a plurality of tabs are formed in the blank area by laser cutting; wherein the laser cutting to form the plurality of tabs comprises: using a first laser beam to pre-cut along a preset cutting path to incompletely cut off the current collector of the blank area in the thickness direction; then using a second laser beam to perform a second fine cutting along the preset cutting path to completely cut off the current collector of the blank area to form the plurality of tabs; the power of the second laser beam is higher than that of the first laser beam.

Description

Technical Field

[0001] This invention belongs to the field of secondary battery technology. More specifically, it relates to a method for preparing a multi-tab battery cell electrode. Background Technology

[0002] In traditional battery cell structures, the electrode typically uses a single tab lead-out method, that is, a current collector tab is set at the head or tail of the entire electrode. This structure exposes significant technical defects in large-size, high-capacity, or high-rate charge-discharge applications: the current density distribution along the length of the electrode (i.e., the current transmission path) is severely uneven.

[0003] To alleviate the above problems, existing technologies have proposed "multi-tab" or "all-tab" design schemes. By setting multiple tabs along the length of the electrode, the current transmission path in the current collector is shortened, which theoretically improves the uniformity of current distribution.

[0004] Among the various manufacturing processes for multi-tab electrodes, laser cutting is widely used for directly forming tabs on current collectors due to its significant advantages such as high processing precision, high speed, and ease of automation. However, those skilled in the art have found in practice that laser cutting is prone to producing metal burrs when cutting the edges of the tabs. This seemingly minor process defect can pose a series of serious challenges to the performance and safety of the battery cell.

[0005] Currently, to address the issue of laser burrs, the industry typically employs secondary processing steps such as "cleaning" or "grinding." However, these methods not only increase the complexity and cost of the production process but may also damage or contaminate the active material coating on the electrode surface. Furthermore, they have limited effectiveness in removing micron-sized burrs and may even transform large burrs into more difficult-to-detect microburrs, failing to fundamentally solve the problem. Summary of the Invention

[0006] The technical problem this invention aims to solve is that existing methods for forming multi-tab battery cells using laser cutting of current collectors easily generate burrs, leading to increased process complexity and cost due to the need for cleaning or polishing. Based on these challenges, this invention provides a method for preparing multi-tab battery cell electrode sheets.

[0007] The purpose of this invention is to provide a method for preparing multi-electrode battery core plates.

[0008] The above-mentioned objective of this invention is achieved through the following technical solution:

[0009] A method for preparing a multi-electrode battery core electrode sheet, the specific preparation steps of which include:

[0010] A battery cell electrode sheet is provided, the battery cell electrode sheet including a current collector, a coating area on which an active material region is coated, and a blank area located on one side of the coating area, which is not coated with an active material region;

[0011] Multiple tabs are formed in the blank area by laser cutting;

[0012] The laser cutting process for forming multiple tabs includes:

[0013] A first laser beam is used to pre-cut along a preset cutting path so as not to completely cut off the current collector of the blank area in the thickness direction;

[0014] Then, a second laser beam is used to perform a second fine cut along the preset cutting path to completely sever the current collector in the blank area, forming the multiple tabs;

[0015] The power of the second laser beam is higher than that of the first laser beam.

[0016] The beneficial effects of the above technical solution are as follows:

[0017] The main causes of burrs in laser cutting are energy input mismatch or insufficient material vaporization. This problem is particularly pronounced for metals like foil, which have high reflectivity and thermal conductivity. For example, common processes use single high-power laser cutting, requiring high energy density to ensure instantaneous vaporization and material cutting. However, this can easily lead to: an excessively large heat-affected zone (HAZ): the cut edge is rapidly melted, and surface tension causes the molten aluminum to aggregate and re-solidify, forming molten burrs. Sputtering and adhesion: the violently vaporized and sputtered molten aluminum can splash and adhere to the lower surface of the cut, forming adhered burrs.

[0018] In the above-described technical solution of this invention, the first weak laser with relatively low power used in the pre-cutting process is not intended to cut, but rather to "pre-treat." It forms a microgroove, a modified line, or a pre-damage zone along the cutting path using low energy. This process is energy-moderate, has minimal heat-affected zone, effectively removes the surface oxide layer, and preheats and micro-melts the material, altering its physical state and energy absorption characteristics.

[0019] Following this, a second high-intensity laser is used for precision cutting, since the path has already been pre-processed:

[0020] Increased energy absorption rate: The pre-cut area has a much higher laser absorption rate than the original glossy aluminum foil surface.

[0021] Reduced energy required: Cutting pre-damaged material requires less energy than cutting whole material directly.

[0022] The cutting is "cleaner": Because the cutting can be completed with relatively lower actual effective power (or higher cutting speed), the total heat input and heat-affected zone of the entire process are effectively controlled. The material is removed more by vaporization rather than being pushed away after melting, thus significantly reducing the generation of molten burrs and attached burrs from the source.

[0023] Furthermore, the second laser beam performs fine cutting immediately after the first laser beam completes the pre-cutting, with the time interval between the two not exceeding 50ms.

[0024] The beneficial effects of the above technical solution are as follows:

[0025] By controlling the interval between the two cuts, it is ensured that the precision cut is performed before the localized high-temperature area generated by the pre-cut has completely cooled down. At this time, the material is in a more easily vaporized state, and the energy required for the second laser can be further optimized. The cutting process is closer to "vaporization cutting" than "melting cutting," resulting in a smaller heat-affected zone and a cleaner cut. If the interval is too long, the preheating effect disappears, and the advantages of dual lasers are diminished.

[0026] Furthermore, the first laser beam and the second laser beam are output by two independent lasers respectively.

[0027] Furthermore, the power of the first laser beam is set to melt or vaporize the surface of the current collector's cutting path, forming a microgroove with a depth of 10-90% of the current collector's thickness.

[0028] The beneficial effects of the above technical solution are as follows:

[0029] A depth of ≥10% ensures that pre-cutting effectively modifies the material physically (e.g., forming microgrooves, changing surface conditions), providing a clear guiding path for precision cutting. A depth of ≤90% ensures that the mechanical integrity of the current collector is maintained after pre-cutting, avoiding premature breakage or displacement of the tabs during high-speed production.

[0030] Furthermore, the power of the first laser beam is set to melt or vaporize the surface of the current collector's cutting path, forming a microgroove with a depth of 40-60% of the current collector's thickness.

[0031] Within the aforementioned range, the microgroove is both deep enough to maximize the guiding and preheating effects of pre-cutting, minimizing the energy requirements for precision cutting, and shallow enough to perfectly maintain the structural strength and stability of the current collector after pre-cutting. Operating within this range typically yields cutting results with minimal burrs and optimal edge quality.

[0032] Furthermore, the current collector is aluminum foil, the power range of the first laser beam is 15-35W, and the power range of the second laser beam is 45-85W.

[0033] The 15-35W pre-cutting power and 45-85W fine cutting power are optimized settings for the high laser absorption rate but easy melting characteristics of aluminum foil. They can perfectly control the heat input and avoid over-melting while ensuring cutting efficiency.

[0034] Furthermore, the current collector is copper foil, the power range of the first laser beam is 80-200W, and the power range of the second laser beam is 250-600W.

[0035] Copper has high reflectivity to infrared lasers and extremely high thermal conductivity, therefore requiring significantly higher power (80-200W for pre-cutting and 250-600W for precision cutting) to initiate and sustain the cut. This parameter range ensures that for difficult-to-machine copper foil, pre-cutting effectively disrupts its highly reflective surface and forms an initial path, while precision cutting provides sufficient energy to complete a clean cut. This range is key to solving the burr problem in copper foil laser cutting.

[0036] Furthermore, during the pre-cutting and precision cutting processes, the cutting speed range of the first laser beam and the second laser beam is 1000-2000 mm / s.

[0037] High cutting speed is a core requirement for cost reduction and efficiency improvement in battery electrode production. Traditional single-laser cutting at such high speeds often requires higher power to ensure a clean cut, leading to more severe burr problems. This invention, through dual-laser synergy, achieves high-quality, low-burr cutting even at high speeds of 1000-2000 mm / s by optimizing energy distribution.

[0038] Furthermore, the current collector is an aluminum foil with a thickness of 10-15 μm; or, the current collector is a copper foil with a thickness of 4.5-8.5 μm. Attached Figure Description

[0039] Figure 1 This is a microscopic cross-sectional view of the electrode tab in Embodiment 1 of the present invention;

[0040] Figure 2 This is a microscopic cross-sectional view of the tab of Comparative Example 1 of the present invention. Detailed Implementation

[0041] The present invention will be further illustrated below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field.

[0042] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0043] Example 1

[0044] A battery cell electrode sheet is provided, the battery cell electrode sheet including a current collector, a coating area on which an active material region is coated, and a blank area located on one side of the coating area, which is not coated with an active material region;

[0045] Among them, the blank area and the coating area extend along the length direction of the cell electrode sheet;

[0046] In the width direction of the cell electrode sheet, the ratio of the width of the blank area to the width of the coating area can be 1:8;

[0047] Multiple tabs are formed in the blank area by laser cutting; the multiple tabs are arranged at intervals along the length direction of the cell electrode sheet.

[0048] The laser cutting process for forming multiple tabs includes:

[0049] A first laser beam is used to pre-cut along a preset cutting path to not completely cut off the current collector in the blank area in the thickness direction; the power of the first laser beam is set to melt or vaporize the surface of the current collector's cutting path to form a microgroove with a depth of 40% of the current collector's thickness.

[0050] Then, a second laser beam is used to perform a second fine cut along the preset cutting path to completely sever the current collector in the blank area, forming the multiple tabs;

[0051] The second laser beam performs fine cutting immediately after the first laser beam completes the pre-cutting, with a time interval of 50ms between the two.

[0052] The first laser beam and the second laser beam are output by two independent lasers respectively;

[0053] The power of the second laser beam is higher than that of the first laser beam;

[0054] When the current collector is aluminum foil, the power of the first laser beam is 20W, the power of the second laser beam is 65W, and the thickness of the aluminum foil is 10μm.

[0055] When the current collector is copper foil, the power of the first laser beam is 120W, the power of the second laser beam is 320W, and the thickness of the copper foil is 4.5μm;

[0056] During the pre-cutting and fine-cutting processes, the cutting speed of the first laser beam and the second laser beam is 1000 mm / s.

[0057] Example 2

[0058] A battery cell electrode sheet is provided, the battery cell electrode sheet including a current collector, a coating area on which an active material region is coated, and a blank area located on one side of the coating area, which is not coated with an active material region;

[0059] Among them, the blank area and the coating area extend along the length direction of the cell electrode sheet;

[0060] In the width direction of the cell electrode sheet, the ratio of the width of the blank area to the width of the coating area can be 1:8;

[0061] Multiple tabs are formed in the blank area by laser cutting; the multiple tabs are arranged at intervals along the length direction of the cell electrode sheet.

[0062] The laser cutting process for forming multiple tabs includes:

[0063] A first laser beam is used to pre-cut along a preset cutting path to not completely cut off the current collector in the blank area in the thickness direction; the power of the first laser beam is set to melt or vaporize the surface of the current collector's cutting path to form a microgroove with a depth of 50% of the current collector's thickness.

[0064] Then, a second laser beam is used to perform a second fine cut along the preset cutting path to completely sever the current collector in the blank area, forming the multiple tabs;

[0065] The second laser beam performs fine cutting immediately after the first laser beam completes the pre-cutting, with a time interval of 46ms between the two.

[0066] The first laser beam and the second laser beam are output by two independent lasers respectively;

[0067] The power of the second laser beam is higher than that of the first laser beam;

[0068] When the current collector is aluminum foil, the power of the first laser beam is 25W, the power of the second laser beam is 60W, and the thickness of the aluminum foil is 12μm.

[0069] When the current collector is copper foil, the power of the first laser beam is 140W, the power of the second laser beam is 360W, and the thickness of the copper foil is 6.5μm;

[0070] During the pre-cutting and precision cutting processes, the cutting speed of the first laser beam and the second laser beam is 1500 mm / s.

[0071] Example 3

[0072] A battery cell electrode sheet is provided, the battery cell electrode sheet including a current collector, a coating area on which an active material region is coated, and a blank area located on one side of the coating area, which is not coated with an active material region;

[0073] Among them, the blank area and the coating area extend along the length direction of the cell electrode sheet;

[0074] In the width direction of the cell electrode sheet, the ratio of the width of the blank area to the width of the coating area can be 1:8;

[0075] Multiple tabs are formed in the blank area by laser cutting; the multiple tabs are arranged at intervals along the length direction of the cell electrode sheet.

[0076] The laser cutting process for forming multiple tabs includes:

[0077] A first laser beam is used to pre-cut along a preset cutting path to not completely cut off the current collector in the blank area in the thickness direction; the power of the first laser beam is set to melt or vaporize the surface of the current collector's cutting path to form a microgroove with a depth of 60% of the current collector's thickness.

[0078] Then, a second laser beam is used to perform a second fine cut along the preset cutting path to completely sever the current collector in the blank area, forming the multiple tabs;

[0079] The second laser beam performs fine cutting immediately after the first laser beam completes the pre-cutting, with a time interval of 40ms between the two.

[0080] The first laser beam and the second laser beam are output by two independent lasers respectively;

[0081] The power of the second laser beam is higher than that of the first laser beam;

[0082] When the current collector is aluminum foil, the power of the first laser beam is 30W, the power of the second laser beam is 65W, and the thickness of the aluminum foil is 15μm.

[0083] When the current collector is copper foil, the power of the first laser beam is 150W, the power of the second laser beam is 400W, and the thickness of the copper foil is 8.5μm;

[0084] During the pre-cutting and precision cutting processes, the cutting speed of the first laser beam and the second laser beam is 2000 mm / s.

[0085] Example 4

[0086] The difference between this embodiment and Embodiment 1 is as follows:

[0087] A first laser beam is used to pre-cut along a preset cutting path to not completely cut off the current collector in the blank area in the thickness direction; the power of the first laser beam is set to melt or vaporize the surface of the current collector's cutting path to form a microgroove with a depth of 10% of the current collector's thickness.

[0088] Accordingly, the relevant cutting parameters need to be adjusted accordingly. Specifically:

[0089] When the current collector is aluminum foil, the power of the first laser beam is 15W, the power of the second laser beam is 45W, and the thickness of the aluminum foil is 10μm.

[0090] When the current collector is copper foil, the power of the first laser beam is 80W, the power of the second laser beam is 250W, and the thickness of the copper foil is 4.5μm;

[0091] The remaining conditions remain basically unchanged.

[0092] Example 5

[0093] The difference between this embodiment and Embodiment 1 is as follows:

[0094] A first laser beam is used to pre-cut along a preset cutting path to not completely cut off the current collector in the blank area in the thickness direction; the power of the first laser beam is set to melt or vaporize the surface of the current collector's cutting path to form a microgroove with a depth of 90% of the current collector's thickness.

[0095] Accordingly, the relevant cutting parameters need to be adjusted accordingly. Specifically:

[0096] When the current collector is aluminum foil, the power of the first laser beam is 35W and the power of the second laser beam is 50W;

[0097] When the current collector is copper foil, the power of the first laser beam is 200W, and the power range of the second laser beam is 300W;

[0098] The remaining conditions remain basically unchanged.

[0099] Example 6

[0100] The difference between this embodiment and Embodiment 1 is that,

[0101] The second laser beam performs fine cutting immediately after the first laser beam completes the pre-cutting, with a time interval of 60ms between the two.

[0102] The remaining conditions remain basically unchanged.

[0103] Comparative Example 1

[0104] The difference between this comparative example and Example 1 is as follows:

[0105] A battery cell electrode sheet is provided, the battery cell electrode sheet including a current collector, a coating area on which an active material region is coated, and a blank area located on one side of the coating area, which is not coated with an active material region;

[0106] Among them, the blank area and the coating area extend along the length direction of the cell electrode sheet;

[0107] In the width direction of the cell electrode sheet, the ratio of the width of the blank area to the width of the coating area can be 1:8;

[0108] Multiple tabs are formed in the blank area by laser cutting; the multiple tabs are arranged at intervals along the length direction of the cell electrode sheet.

[0109] A laser beam is used to pre-cut along a preset cutting path to completely sever the current collector in the blank area in one go in the thickness direction;

[0110] Wherein, when the current collector is aluminum foil, the power of the laser beam is 95W; and the thickness of the aluminum foil is 10μm;

[0111] When the current collector is copper foil, the power of the laser beam is 660W; the thickness of the copper foil is 4.5μm.

[0112] The burr condition of the products obtained in the examples and comparative examples was inspected, and the specific inspection methods and results are as follows:

[0113] The cross-section of the cut electrode tab was observed, and the size of the burrs was tested using measuring tools.

[0114] Taking the view of Example 1 as an example, the cut cross-section is flat and smooth, with no obvious burrs; and the views of Examples 2 and 3 are similar to those of Example 1.

[0115] The remaining embodiments and comparative examples show burrs, and the specific morphology of the burrs is as follows: Figure 2 As shown, Figure 2 Specifically, the burr situation of Comparative Example 1 and the maximum burr size, i.e., 88.58 μm, are shown; correspondingly, the maximum burr size of Example 4 is 5.25 μm; the maximum burr size of Example 5 is 7.88 μm; and the maximum burr size of Example 6 is 4.98 μm.

[0116] The test results above show that when using the technical solution of this invention to laser cut the electrode sheet of a multi-tab, the problem caused by burrs can be significantly reduced.

[0117] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a multi-electrode battery core electrode, characterized in that, The specific preparation steps include: A battery cell electrode sheet is provided, the battery cell electrode sheet including a current collector, a coating area on which an active material region is coated, and a blank area located on one side of the coating area, which is not coated with an active material region; Multiple tabs are formed in the blank area by laser cutting; The laser cutting process for forming multiple tabs includes: A first laser beam is used to pre-cut along a preset cutting path so as not to completely cut off the current collector of the blank area in the thickness direction; Then, a second laser beam is used to perform a second fine cut along the preset cutting path to completely sever the current collector in the blank area, forming the multiple tabs; The power of the second laser beam is higher than that of the first laser beam; The second laser beam performs fine cutting immediately after the first laser beam completes the pre-cutting, and the time interval between the two does not exceed 50ms.

2. The method for preparing a multi-electrode battery core electrode sheet according to claim 1, characterized in that, The first laser beam and the second laser beam are output by two independent lasers.

3. The method for preparing a multi-electrode battery core electrode sheet according to claim 1, characterized in that, The power of the first laser beam is set to melt or vaporize the surface of the current collector's cutting path, forming a microgroove with a depth of 10-90% of the current collector's thickness.

4. The method for preparing a multi-electrode battery core electrode sheet according to claim 3, characterized in that, The power of the first laser beam is set to melt or vaporize the surface of the current collector's cutting path, forming a microgroove with a depth of 40-60% of the current collector's thickness.

5. The method for preparing a multi-electrode battery core electrode sheet according to claim 3, characterized in that, The current collector is aluminum foil, the power range of the first laser beam is 15-35W, and the power range of the second laser beam is 45-85W.

6. The method for preparing a multi-electrode battery core electrode sheet according to claim 3, characterized in that, The current collector is copper foil, the power range of the first laser beam is 80-200W, and the power range of the second laser beam is 250-600W.

7. The method for preparing a multi-electrode battery core electrode sheet according to claim 1, characterized in that, During the pre-cutting and precision cutting processes, the cutting speed range of the first laser beam and the second laser beam is 1000-2000 mm / s.

8. The method for preparing a multi-electrode battery core electrode sheet according to claim 1, characterized in that, The current collector is an aluminum foil with a thickness of 10-15 μm; or, the current collector is a copper foil with a thickness of 4.5-8.5 μm.

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