Date: 2026-04-22 hits: 105
In the manufacturing process of lithium batteries, electrode rolling is a critical step. During this process, wrinkles often occur in the blank areas. Wrinkles at the tabs affect the welding strength, leading to poor welding or increased battery resistance, resulting in rapid heat generation during charging and discharging and accelerated cycle life degradation. Tab wrinkles can also cause separator punctures, leading to short circuits and other problems. This not only affects the battery's appearance but may also adversely impact its performance and safety. This article will discuss the causes, solutions, and precautions for wrinkles in the blank areas during lithium battery electrode rolling to improve the manufacturing quality of lithium batteries.
I. General Lithium-ion Battery Manufacturing Process
The production of lithium-ion batteries is a process involving multiple closely linked steps, mainly including battery electrode fabrication, battery cell fabrication, and capacity testing. The battery electrode manufacturing process includes four steps: slurry preparation, coating, roll forming and slitting, and laser cutting, collectively known as the front-end. Battery cell manufacturing includes four steps: winding, assembly, laser welding, and baking, collectively known as the middle-end. The capacity testing stage includes four steps: liquid injection and sealing, cleaning, formation, and capacity testing, collectively known as the back-end. Each step significantly impacts the final battery performance.
II. Coating Process
The main purpose of the coating process is to uniformly coat the qualified slurry onto the positive/negative current collectors. Specifically, after the slurry is dispersed by a high-speed disperser, it is fed into the coating machine die head and uniformly coated onto the foil material intermittently or continuously according to design requirements. Then, it is dried in an oven. Subsequently, the dried electrode sheets are wound up under a certain tension. During the coating process, areas without coating material are usually left on both sides of the foil material. These uncoated areas can be used as battery tabs after laser cutting, or they can be left uncut to produce all-tab batteries.
III. Reasons for Wrinkles in the Uncoated Areas of the Electrode Sheets
1. Inconsistent Expansion
In the rolling process of lithium battery electrodes, inconsistent elongation between the coating area and the foil area is one of the main causes of wrinkles in the blank areas. This may be due to differences in material properties, uneven thickness, or processing techniques between the coating and foil areas. When the elongation is inconsistent, the deformation degrees of the coating and foil areas differ during rolling, leading to stress concentration in the blank areas and ultimately wrinkles.
2. Rolling Process
Parameters Improper setting of rolling process parameters can also cause wrinkles in the blank areas of the electrode. For example, excessively high or low rolling pressure, excessively fast or slow rolling speed, and unsuitable temperatures can all affect the elongation and uniformity of the electrode, thus causing wrinkles in the blank areas.
3. Electrode Design
The design of the tabs should control the length of the blank areas on both sides, or use a method of cutting the tabs before rolling to avoid ineffective stress distribution during rolling, which increases the risk of wrinkles.
IV. Solutions
1. Material Selection and Optimization
To reduce wrinkling in the tab blank area, coating materials and foils with good ductility and uniformity should be selected first. Strict quality control is crucial during material procurement to ensure material performance meets requirements. Furthermore, optimizing the coating formulation and preparation process can improve the ductility of the coating area and its compatibility with the foil area.
2. Stretching Treatment
To address the inconsistency in ductility between the coating and foil areas, the electrode can be stretched. Stretching treatment brings the ductility of the coating and foil areas closer together, reducing the possibility of stress concentration. During stretching, it is important to control the stretching force and speed to avoid overstretching and damaging the electrode.
3. Optimizing the Rolling Process
Properly adjusting the rolling process parameters is key to solving the wrinkling problem. Suitable rolling pressure, speed, and temperature parameters can be determined through experiments and simulation analysis to ensure uniform stretching of the electrode during rolling, reducing wrinkling. Simultaneously, the rolling mill should be kept in good working condition, with regular inspection and maintenance to ensure its accuracy and stability.
4. Optimize Electrode Design: The design of the tabs should carefully control the length of the blank areas on both sides, or employ a method of cutting the tabs before rolling to avoid ineffective stress distribution during rolling, which increases the risk of wrinkling.
5. Quality Inspection and Control: A comprehensive quality inspection system should be established during the manufacturing process of lithium battery electrodes to monitor the appearance quality and performance of the electrodes in real time. Through online inspection and sampling inspection, problems such as wrinkles in the blank areas of the tabs should be identified promptly, and corresponding measures should be taken for adjustment and improvement. In addition, the production process should be strictly controlled to ensure the stability and consistency of various process parameters.
V. Precautions
1. Appropriate Stretching Treatment During stretching treatment, attention should be paid to moderate stretching to avoid overstretching, which can lead to electrode deformation or performance degradation. A reasonable degree of stretching needs to be determined based on specific material and process requirements.
2. Monitoring the Rolling Process: During the rolling process, the condition of the electrodes should be closely monitored to promptly identify and resolve any potential problems.
3. Equipment Maintenance and Upkeep: Good equipment condition is crucial for preventing tab wrinkling. Regular maintenance and upkeep of the rolling mill are necessary, including checking the wear, flatness, and cleanliness of the rollers to ensure normal equipment operation.
4. Operator Training: The skills and experience of operators directly impact the manufacturing quality of lithium battery electrodes. Therefore, it is crucial to strengthen operator training, improving their understanding and mastery of the rolling process and equipment to ensure standardized and accurate operation.
VI. Conclusion
Wrinkling in the tab blank area during lithium battery electrode rolling is a significant factor affecting lithium battery manufacturing quality. Through analysis of the causes of wrinkling in the tab blank area, corresponding solutions and precautions are proposed. The comprehensive application of measures such as material selection and optimization, stretching treatment, optimized rolling process, and quality inspection and control can reduce wrinkling and improve the performance and reliability of lithium batteries. The above solutions are for reference only. In actual production, appropriate methods should be selected based on specific circumstances (effective and innovative patented solutions and methods can also be referenced), and precautions should be strictly followed. Continuous optimization of processes and management is essential to improve the overall quality of lithium batteries.
