A method for coating an electrode tab to prevent cracking

Abstract

The application discloses a kind of electrode polar piece's coating anti-cracking method, comprising: step S1, intermittent traction operation is executed: electrode polar piece is obtained to complete intermittent traction;Step S2, stress release operation is executed: electrode polar piece is obtained to complete stress release;Step S3, width reverse humidity coupling drying operation is executed: in oven, continue to be carried out to the electrode polar piece of step S2, stress release is completed, and region is carried out humidification operation and hot air drying operation;Step S4, low-temperature conformal shaping operation is executed: in oven, continue to be carried out to the polar piece of step S3, in the preset low-temperature region in oven, and rest for a preset time, obtain the electrode polar piece of finished product.The electrode polar piece's coating anti-cracking method disclosed in the application can establish active control system covering stress generation, accumulation, release and elimination whole process, realize stress dynamic balance regulation and control in whole drying process, and be beneficial to solve coating cracking problem under thick coating, high solid content, high-speed coating working condition.

Description

Technical Field

[0001] This invention relates to the field of electrode technology, and in particular to a method for coating electrode sheets to prevent cracking. Background Technology

[0002] As the new energy storage market continues to demand high energy density, high power density, and long cycle life, the electrode sheets of electrochemical energy storage devices such as lithium-ion batteries, supercapacitors, and sodium-ion batteries are rapidly developing towards high areal density, thick coating, high solid content, and high viscosity.

[0003] In continuous high-speed coating production, the slurry is transferred from the coating head to the current collector surface of the electrode sheet and then enters the oven to complete solvent evaporation and coating curing. Due to the long solvent diffusion path inside the thick coating, the large difference in drying rate between the surface and inner layers, and the uneven distribution of temperature and air velocity in the width direction, it is very easy to cause asynchronous coating shrinkage, internal stress concentration, microcrack initiation and rapid propagation, which ultimately leads to serious defects such as surface cracking, edge cracking, warping deformation, interlayer peeling of coating, and even debonding of coating from current collector on the electrode sheet.

[0004] The aforementioned defects not only directly lead to poor appearance of the electrode sheets and reduced process yield, but also damage the internal conductive network structure of the electrode, reduce ion transport efficiency and electronic conductivity, and ultimately affect the rate performance, cycle stability and safety reliability of the battery cell.

[0005] The mainstream technical solutions currently used in the industry to address the coating cracking problem of electrode sheets generally suffer from significant limitations, limited effectiveness, and an inability to solve the problem at its root. These are explained in detail below: The first approach involves modifying the binder or adding anti-cracking additives to improve cracking. This method relies on modifying polymer materials or compounding additives to enhance coating toughness, but it directly alters the original electrochemical system of the slurry, reduces the proportion of active materials and ionic conductivity, increases raw material costs, and has poor compatibility with different active material systems. It is prone to problems such as uneven slurry dispersion, sedimentation, and viscosity drift, making it difficult to adapt to the large-scale production of multi-material systems.

[0006] The second approach involves using a double-layer or multi-layer step-by-step coating structure. By applying and drying layers in stages, the thickness of each single layer is reduced to decrease internal stress. However, this approach significantly increases equipment investment, process complexity, and production cycle time. Defects and high-resistivity areas are easily formed at the interfaces between coating layers, reducing the stability of the electrode structure. Furthermore, it cannot be adapted to high-speed continuous production lines, resulting in a substantial increase in overall costs.

[0007] The third method involves using a traditional three-stage heating and drying process. This method relies solely on temperature gradients for drying control, without considering solvent evaporation kinetics and stress evolution. It fails to match the drying and shrinkage sequence of the coating from the surface inwards, resulting in insufficient stress release, a high risk of concentrated stress bursts, and a weak effect on suppressing cracking in thick coatings and high-solids-content electrode sheet coatings.

[0008] The fourth method relies on passive remedial measures such as edge hot air compensation, overall humidification, and edge trimming. These methods can only locally alleviate surface defects, cannot achieve synchronous shrinkage in the width direction, and cannot eliminate the root cause of stress concentration. Under high-speed and thick coating conditions, they are almost unable to stably control the coating cracking of electrode sheets. They are post-correction rather than source prevention.

[0009] In summary, existing technologies are limited to local optimization, passive compensation, and post-processing correction, and cannot achieve dynamic stress balance control throughout the drying process, making it difficult to completely solve the coating cracking problem under conditions of thick coating, high solids content, and high-speed coating.

[0010] Therefore, there is an urgent need to develop a technology that can solve the above-mentioned technical problems. Summary of the Invention

[0011] The purpose of this invention is to address the technical deficiencies of existing technologies by providing a method for preventing cracking when coating electrode sheets.

[0012] Therefore, the present invention provides a method for preventing cracking when coating electrode sheets, which includes the following steps: Step S1, perform intermittent traction operation: For the electrode sheet after the slurry coating is completed, the electrode sheet is tractioned in advance according to the preset intermittent method to obtain the electrode sheet after intermittent traction. Step S2, perform stress relief operation: transfer the electrode sheet obtained in step S1 after intermittent traction into the oven; After the electrode sheet enters the oven, a stress-relieving zone is set along its direction of travel. Within this stress-relieving zone, the forward speed of the electrode sheet is reduced, and the electrode sheet is allowed to remain statically for a preset time to obtain an electrode sheet that has completed stress relief. Step S3, perform width reverse humidity coupling drying operation: In the oven, continue to perform humidification and hot air drying operations on the electrode sheet that has completed stress release obtained in step S2, so that the humidity in the central area of ​​the electrode sheet is higher than that in the edge area, and the hot air velocity in the edge area of ​​the electrode sheet is higher than that in the central area. Step S4: Perform low-temperature shaping operation: In the oven, continue to place the electrode sheet obtained in step S3 in the preset low-temperature area of ​​the oven for a preset time to obtain the finished electrode sheet.

[0013] As can be seen from the technical solution provided by the present invention above, compared with the prior art, the present invention provides a method for preventing cracking in the coating of electrode sheets. Its design is scientific and can establish an active control system for the entire process of stress generation, accumulation, release and elimination, and realize dynamic balance control of stress throughout the drying process. It is beneficial to solve the problem of coating cracking under thick coating, high solid content and high speed coating conditions, and has great practical significance.

[0014] The method of the present invention is a coating gradient micro-stress relief and crack prevention preparation method that does not require changes to the slurry formulation, does not involve multi-layer coating structure, and is not a traditional temperature-air gradient drying method. It is beneficial to overcome various defects of the existing technology.

[0015] Practical testing has proven that the method of this invention is a radical anti-cracking coating method that requires no formula modification, no multi-layer coating, does not rely on traditional temperature and air gradients, and is directly compatible with existing production lines. This invention's anti-cracking coating method for electrode sheets addresses surface cracking, edge cracking, and network cracking problems caused by surface crusting and uneven shrinkage stress during coating and drying of thick slurry coatings and high-solids-content slurry coatings. It employs control mechanisms such as current collector microtexturing, a temperature and humidity gradient air field along the width, dynamic stress relief rhythm, and asymmetric edge slow release to fundamentally solve cracking from the perspective of shrinkage mechanics balance. It does not modify the slurry formula, does not require double-layer coating, and does not rely on new binders, significantly improving the yield of electrode sheets.

[0016] The electrode coating anti-cracking method provided by this invention is an electrode coating drying control process for thick coating, high solid content, and high-speed continuous production scenarios. It is also a method that controls the dynamic micro-relaxation of belt tension, the sequential dwell time during key drying stages, the coupling of reverse humidity field across the width, and the low-temperature shape preservation residual stress. By achieving the gradual release of coating drying shrinkage stress gradient and synchronous equalization of deformation, it fundamentally solves common industry problems such as electrode coating cracking, edge warping, and insufficient interlayer bonding. Attached Figure Description

[0017] Figure 1 The flowchart illustrates a method for preventing cracking when coating an electrode sheet, as provided by this invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0020] In the description of this patent, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this patent according to the specific circumstances.

[0021] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0022] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0023] See Figure 1 This invention provides a method for preventing cracking when coating electrode sheets, comprising the following steps: Step S1, perform intermittent traction operation: For the electrode sheet after the slurry coating is completed, the electrode sheet is tractioned in advance according to the preset intermittent method to obtain the electrode sheet after intermittent traction. In step S1, specifically, the electrode sheet is a battery electrode sheet or a supercapacitor electrode sheet; In step S1, specifically, the electrode plates are pre-tractioned according to a preset intermittent method, which includes the following operations: The electrode plates are intermittently pulled according to the preset micro-relaxation amount; Intermittent traction means that after each preset length of traction, the electrode plate is released from tension for a preset duration (i.e., traction is paused and the electrode plate is released). Furthermore, in step S1, the preset micro-relaxation amount is preferably 0.1‰–0.5‰ of the total length of the electrode sheet, which is used to eliminate (i.e., offset) the instantaneous tensile stress formed on the electrode sheet during the subsequent drying process.

[0024] Furthermore, in step S1, every 200–500 mm of traction travel, the electrode plate undergoes a tension release of 0.2–0.8 s, with a relaxation amount of 0.1‰–0.5‰ of the total length of the electrode plate, in order to eliminate the instantaneous tensile stress during drying; It should be noted that the relaxation amount in intermittent traction is the stress amplitude (or deformation rebound) released during the traction force release phase, that is, the decrease in force or displacement during the recovery process from a non-equilibrium state to an equilibrium state.

[0025] In step S1, specifically, the intermittent traction operation is an intermittent micro-relaxation traction operation, which can be achieved by periodic forward and reverse micro-compensation of the servo traction roller, with tension fluctuation ≤ ±1.5%. One end of the electrode sheet is wound around the circumferential outer side of the servo traction roller.

[0026] Step S2, perform stress relief operation: transfer the electrode sheet obtained in step S1 after intermittent traction into the oven; After the electrode sheet enters the oven, a stress-relieving zone is set along its direction of travel. Within this stress-relieving zone, the forward speed of the electrode sheet is reduced, and the electrode sheet is allowed to remain statically for a preset time to obtain an electrode sheet that has completed stress relief. In step S2, specifically, when the peak evaporation time of the solvent in the slurry coated on the surface of the electrode current collector is reached (which is measured in advance by existing methods and the peak time is a time period that is greater than the preset solvent evaporation rate threshold), the forward speed of the electrode is reduced in the residence stress relief zone, and the electrode is allowed to remain statically for a preset time. Furthermore, in step S2, when the solvent in the slurry coated on the surface of the electrode current collector is at its peak evaporation time, the forward linear velocity of the electrode is reduced by 1%–3% (i.e., decelerated by 1%–3%) and held for 0.5–1.5 seconds, thereby preventing the electrode from cracking due to internal stress accumulation. It should be noted that the stress-relieving zone of the electrode sheet is a region in the oven used to slow down the electrode sheet and allow it to remain stationary in order to release the internal stress of the electrode sheet.

[0027] In step S2, specifically, the stress-relieving zone is located in a preset area inside the oven, and the solid content of the coating on the corresponding electrode sheet is in the range of 30%–70%. In specific implementation, the preset area inside the oven is, for example, the second to fourth temperature zones (high temperature zone) in an existing conventional industrial continuous coating oven that includes six temperature zones (for example, typically including a preheating zone, a constant temperature evaporation zone, a heating and deep drying zone, a high temperature curing zone, a uniform temperature stabilization zone, and a cooling transition zone, distributed in sequence). In step S2, specifically, an oven can be used to provide a temperature environment of 80-100°C for the electrode plates inside the oven.

[0028] Step S3, perform width-reverse humidity coupling drying operation: In the oven, continue to perform humidification and hot air drying operations on the electrode sheet obtained in step S2 after stress release, so that the humidity in the central area of ​​the electrode sheet (i.e., the preset length area in the middle of the electrode sheet width direction) is higher than the humidity in the edge area, and the hot air velocity in the edge area of ​​the electrode sheet is higher than the hot air velocity in the central area. It should be noted that for an electrode sheet, its central region is a predetermined length region located at the middle of the electrode sheet width direction, and the two sides of the central region in the electrode sheet width direction have edge regions distributed along the electrode sheet length direction.

[0029] In step S3, specifically, the humidity in the central region of the electrode sheet is 5%–12% higher than that in the peripheral region. The hot air velocity in the edge region of the electrode sheet is 8%–18% higher than that in the center region. Therefore, it is beneficial to achieve full-width synchronous shrinkage of the central and edge regions of the battery electrode sheet coating during the hot air drying process.

[0030] In step S3, specifically, the reverse humidity coupling of the battery electrode can be achieved by humidifying the central area of ​​the nozzle and independently exhausting the peripheral area. In step S3, specifically, the relative humidity of the central area of ​​the battery electrode is 30%–50%, and the relative humidity of the peripheral area is 20%–35%.

[0031] Step S4, perform low-temperature shaping operation: In the oven, continue to place the electrode sheet obtained in step S3 in the preset low temperature zone of the oven for a preset time (e.g., 24 hours) to obtain the finished electrode sheet.

[0032] In step S4, specifically, the temperature of the preset low-temperature zone inside the oven is 10–20°C lower than the temperature of the area inside the oven where the electrode plates are located in step S3 (i.e., the drying zone in front).

[0033] It should be noted that, for the present invention, a low-temperature shaping process is performed at the end of the drying process of the electrode sheet. The temperature at this time is 10–20°C lower than the temperature of the main drying area (i.e., the area inside the oven where the electrode sheet is located in step S3) to eliminate residual stress on the electrode sheet.

[0034] After testing, the above-described method of the present invention is applicable to coatings with a surface density of slurry of 180–350 g / m². 2 And the electrode sheets are processed at a coating speed of 30–80 m / min.

[0035] To better understand the technical solution of the present invention, the design principle of the present invention is explained below.

[0036] The method of this invention is a coating gradient micro-stress-releasing anti-cracking preparation method that does not require changes to the slurry formulation, multi-layer coating structure, or traditional temperature-air gradient drying. Based on the dual core mechanisms of dynamic temporal control of stress and synchronous coupling of width and deformation, this invention constructs a four-fold synergistic control mechanism: intermittent micro-relaxation traction stress control, energy release during critical stress segment residence, width-reverse humidity field coupling, and low-temperature shape preservation and residual stress elimination. This achieves precise stress relief throughout the entire stress chain and synchronous equilibrium of deformation across the entire domain, fundamentally blocking the crack initiation and propagation path, and completely solving the problem of electrode coating cracking.

[0037] 1. Intermittent micro-relaxation traction stress control; This invention employs a periodic, quantitative micro-relaxation traction mode triggered by a closed loop in both length and time dimensions, completely different from conventional methods such as constant tension control, passive compensation with floating rollers, and constant deflection control. During the critical stage after the coating enters the oven and the drying shrinkage stress rapidly increases, a small amount of tension is released instantaneously according to a preset length and time cycle. This actively counteracts the drying shrinkage tensile stress generated in the longitudinal and transverse directions of the coating in a very small amplitude, high frequency, and stable, impact-free manner. This method avoids excessive stress concentration at coating edges, internal weak areas, and interface joints, while ensuring smooth belt movement, preventing deviation, wrinkling, and irreversible stretching, and maintaining coating thickness uniformity and the stability of the current collector interface.

[0038] 2. Energy release during the critical stress zone; Based on the solvent evaporation rate curve and the stress evolution law of the coating, this invention can accurately locate the high-risk critical range of solvent evaporation peak, rapid increase in coating modulus, and exponential accumulation of internal stress. Within this range, a small stepwise reduction in linear velocity and a short-term static dwell time are implemented to provide sufficient stress relaxation time window for the coating of the electrode sheet. This allows the concentrated shrinkage stress inside the electrode sheet to be uniformly dispersed and gradually released, thereby blocking microcrack nucleation, inhibiting crack propagation along the width and direction of cracks, and preventing microcracks from developing into macroscopic cracks from the source.

[0039] 3. Width-inverse humidity field coupling; This invention completely overturns the industry's conventional control logic of "high humidity at the edges and low humidity at the center" or uniform humidity or wind speed throughout the entire area. It innovatively constructs a reverse humidity distribution field with high humidity and slow drying at the center and low humidity and fast drying at the edges. Combined with independent and differentiated wind speed adjustment in the width direction, it ensures that the central and edge areas of the electrode coating maintain synchronous shrinkage rate, consistent deformation process, and similar setting time throughout the drying process. This fundamentally eliminates the shear stress, tearing stress, and bending stress caused by the difference in shrinkage between the edges and the center of the electrode, achieving a balanced stress distribution across the entire width of the electrode.

[0040] 4. Low-temperature shape preservation and stress relief; This invention sets up an independent low-temperature shaping zone at the end of the drying process. It adopts a mild working condition with low temperature, low wind speed, weak convection, and no wind impact to deeply eliminate residual stress in the electrode coating that has been basically formed and cured. Through slow cooling, stable dehumidification, and gradient stress relaxation, the residual stress inside the coating and at the interface is completely released. This avoids problems such as cracking, warping, deformation, and dimensional rebound caused by sudden temperature changes, stress rebound, and changes in ambient humidity after the electrode leaves the oven, which significantly improves the dimensional stability and long-term reliability of the electrode.

[0041] The process of this invention, through the synergistic effect of the above four mechanisms, achieves active and controllable stress control throughout the entire process from generation, accumulation, release to elimination. It can achieve stable production of electrode sheets without cracking, warping, or peeling under high-speed, thick-coating, and high-solids conditions without changing the slurry formula, increasing the number of coating layers, or significantly modifying the equipment. It has outstanding advantages such as simple process, strong compatibility, low cost, and stable effect.

[0042] To better understand the technical solution of the present invention, the following specific embodiments will be used to illustrate the technical solution of the present invention.

[0043] Example 1.

[0044] This embodiment uses activated carbon-based supercapacitor electrodes as the processing target, with a designed areal density of 290 g / m³. 2 The specific process parameters and implementation steps for applying the method of this invention on an existing high-speed continuous coating production line are as follows: Step S1, Intermittent micro-relaxation traction control: The length and time dual closed-loop triggering mode is adopted. The length cycle is set to 300mm, the time cycle is set to 0.5s, the longitudinal micro-relaxation amount is controlled at 0.2‰, and the tension is adjusted in real time to ensure that the tension fluctuation is controlled within a very small range. The entire belt travel is smooth without impact, shaking, or deviation.

[0045] Step S2, Critical Stress Section Residence Energy Release Control: Based on the solvent evaporation characteristics, the critical stress zone is located. The third temperature zone of the oven, which includes six temperature zones (used to remove solvent moisture from the electrode slurry through heating to avoid stress accumulation), is selected as the residence zone. This zone is where the solvent evaporation peak and the point of rapid stress accumulation occur. The linear velocity is slightly reduced by 2%, and the residence time is maintained at 1.0s to allow the coating to fully relax, preventing stress concentration and crack initiation.

[0046] Step S3, Width-inverse humidity field coupling control: Establish differentiated humidity and wind speed distribution in the width direction: maintain the ambient humidity in the central area of ​​the electrode sheet at 40%, and maintain the ambient humidity in the edge area of ​​the electrode sheet at 28%; at the same time, set the air supply speed in the edge area of ​​the electrode sheet to be 12% higher than that in the central area, forming a reverse coupling field with slow drying in the central area and fast drying in the edge area, ensuring synchronous contraction across the entire width.

[0047] Step S4, Low-temperature shaping and stress relief: A shaping zone is set up at the end of the drying section in the oven. The temperature is reduced by 15°C compared to the previous drying zone. A low wind speed, no wind impact, and weak convection mode are used to complete the final shaping and stress relief of the coating on the electrode sheet, so as to avoid stress rebound and deformation of the electrode sheet after it leaves the oven.

[0048] In terms of specific implementation, the overall stable operating speed of the electrode sheet continuous coating production line is set to 55m / min, which can meet the requirements of high-speed large-scale continuous production. The process parameters are stable and adjustable, and can be adapted to different surface densities, widths and material systems.

[0049] In specific implementation, combined with the process method of this invention, under continuous large-scale production conditions, the activated carbon electrode sheets prepared using the method of this invention exhibit excellent consistency in appearance and performance: the coating is free from surface cracking, edge cracking, warping deformation, interlayer delamination, and interface debonding; the bonding force between the electrode sheet and the current collector meets stringent process requirements; and the overall production yield reaches 99.8%. Simultaneously, the electrode sheet has a complete internal structure and a uniform conductive network, and its electrical performance, rate characteristics, and cycle stability are significantly superior to electrode sheets prepared by traditional processes, making it suitable for direct use in the manufacture of high-end supercapacitor cells.

[0050] In summary, compared with the prior art, the electrode coating crack prevention method provided by the present invention has the following beneficial technical effects: 1. Zero changes to the formula, more stable system: No need to modify the binder, no need to add crack-resistant additives, does not change the electrochemical properties of the slurry, does not affect ion and electron transport, has strong versatility, low raw material cost, and high stability of the slurry system; 2. Crack prevention can be achieved with a single layer of coating: No need for double or multiple layers of coating, the process is simple and efficient, without increasing the number of processes and equipment investment, and is directly compatible with existing high-speed coating production lines, requiring minimal modification and quick implementation; 3. Curing cracking from the root: Replacing local passive remedies with active control of stress throughout the entire chain, achieving balanced stress release and synchronous deformation, and completely solving the stubborn problem of coating cracking under thick coating, high solids content, and high speed conditions; 4. Significantly improved electrode quality: High electrode size consistency, no internal defects, and strong interface bonding, significantly improving production yield, cell performance and lifespan, and reducing overall manufacturing costs.

[0051] 5. Flexible and adaptable process: The control parameters can be digitally closed-loop adjusted, which can quickly adapt to various active material systems such as activated carbon, graphite, silicon carbide, ternary lithium, and lithium iron phosphate, as well as the production of electrode sheets with different surface densities and widths. It has a wide range of applications and high promotion value.

[0052] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for coating electrode sheets to prevent cracking, characterized in that, Includes the following steps: Step S1, perform intermittent traction operation: For the electrode sheet after the slurry coating is completed, the electrode sheet is tractioned in advance according to the preset intermittent method to obtain the electrode sheet after intermittent traction. Step S2, perform stress relief operation: transfer the electrode sheet obtained in step S1 after intermittent traction into the oven; After the electrode sheet enters the oven, a stress-relieving zone is set along its direction of travel. Within this stress-relieving zone, the forward speed of the electrode sheet is reduced, and the electrode sheet is allowed to remain statically for a preset time to obtain an electrode sheet that has completed stress relief. Step S3, perform width reverse humidity coupling drying operation: In the oven, continue to perform humidification and hot air drying operations on the electrode sheet that has completed stress release obtained in step S2, so that the humidity in the central area of ​​the electrode sheet is higher than that in the edge area, and the hot air velocity in the edge area of ​​the electrode sheet is higher than that in the central area. Step S4: Perform low-temperature shaping operation: In the oven, continue to place the electrode sheet obtained in step S3 in the preset low-temperature area of ​​the oven for a preset time to obtain the finished electrode sheet.

2. The method for preventing cracking of electrode sheets as described in claim 1, characterized in that, Electrode plates are either battery electrodes or supercapacitor electrodes.

3. The method for preventing cracking of electrode sheets as described in claim 1, characterized in that, In step S1, the electrode plates are pre-tractioned according to a preset intermittent method, specifically including the following operations: The electrode plates are intermittently pulled according to the preset micro-relaxation amount; Intermittent traction means that after each preset length of traction, the electrode plate releases tension for a preset duration.

4. The method for preventing cracking of electrode sheets as described in claim 3, characterized in that, In step S1, the preset micro-relaxation amount is 0.1‰–0.5‰ of the total length of the electrode sheet.

5. The method for preventing cracking of electrode sheets as described in claim 1, characterized in that, In step S1, for every 200–500 mm of traction travel, the electrode plate undergoes a tension release of 0.2–0.8 s, with a relaxation amount of 0.1‰–0.5‰ of the total length of the electrode plate.

6. The method for preventing cracking of electrode sheets as described in claim 1, characterized in that, In step S2, when the solvent in the slurry coated on the surface of the electrode current collector is at its peak evaporation time, the forward speed of the electrode is reduced in the stress-relieving zone, and the electrode is allowed to remain statically for a preset time.

7. The method for preventing cracking of electrode sheets as described in claim 6, characterized in that, In step S2, when the solvent in the slurry coated on the surface of the electrode current collector is at its peak evaporation time, the forward linear velocity of the electrode is reduced by 1%–3%, and the electrode is held for 0.5–1.5 seconds.

8. The method for preventing cracking of electrode sheets as described in claim 1, characterized in that, In step S3, the humidity in the central region of the electrode sheet is 5%–12% higher than that in the peripheral region; The hot air velocity at the edge of the electrode sheet is 8%–18% higher than that in the center.

9. The method for preventing cracking of electrode sheets as described in claim 1, characterized in that, In step S3, the relative humidity of the central area of ​​the battery electrode is 30%–50%, and the relative humidity of the peripheral area is 20%–35%.

10. The method for preventing cracking of electrode sheets as described in any one of claims 1 to 9, characterized in that, In step S4, the temperature of the preset low-temperature zone inside the oven is 10–20°C lower than the temperature of the zone inside the oven where the electrode plates are located in step S3.

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