Date: 2024-11-29 hits: 161
The performance and quality of lithium batteries still face many challenges, among which the quality of electrode plates is one of the key factors affecting battery performance. The wavy edge of lithium battery electrodes is a common but easily overlooked issue, which not only affects the appearance of the battery, but also poses a potential threat to the performance and safety of the battery. Therefore, it is of great practical significance to conduct in-depth research on the causes, effects, and coping strategies of the wavy edges of lithium battery electrodes.
Definition of Wave Edge for Lithium Battery Pole Plates
The wavy edge of lithium battery electrode refers to the irregular undulations of the electrode edge, which no longer maintains a flat shape. This uneven edge can have a series of adverse effects on the manufacturing and performance of batteries.
The Cause of Wave Edges in Lithium Battery Pole Plates
（1） The material properties of lithium battery electrodes with insufficient or uneven yield stress have a significant impact on their forming quality. If the yield stress of the material is insufficient or unevenly distributed inside the pole piece, it is prone to deformation during the manufacturing process when subjected to external forces, resulting in wave edge phenomena at the edge of the pole piece.
（2） The precision and stability of equipment used to manufacture lithium battery electrodes are one of the key factors determining the quality of the electrodes. For example, insufficient coating accuracy of the coating machine, uneven rolling of the roller press, and tool wear of the slitting machine may all lead to uneven force on the polarizer during processing, resulting in wavy edges.
（3） Coating process issues or insufficient drying during the coating process, improper control of the coating speed and thickness of the slurry, or uneven temperature and wind speed during the drying process, can all lead to uneven stress distribution inside the polarizer, resulting in wavy edges in subsequent processing.
（4） The consistency of electrode thickness is an important prerequisite for ensuring its stable performance. If the thickness of the polarizer is uneven due to various reasons during the preparation process, the thinner and thicker parts will experience different forces and deformations during subsequent processing and use, which can easily cause wavy edges.
The influence of wavy edges on lithium battery electrodes
（1） The wave edge at the edge of the electrode can cause uneven current distribution on the electrode surface, thereby affecting the charging and discharging efficiency and rate performance of the battery. During the charging process, excessive local current may lead to lithium deposition, while during the discharging process, the areas where the current is concentrated may reach the discharge cut-off voltage too early, thereby reducing the overall capacity and energy output of the battery.
（2） The uneven internal stress caused by wave edges on the battery cycle life will accumulate and intensify during the repeated charging and discharging process of the battery, leading to the destruction of the electrode structure and the detachment of active substances. This will directly shorten the cycle life of the battery, reduce its value and reliability.
（3） Uneven edge of the electrode can cause uneven distribution of internal stress and safety in the battery, which may lead to expansion during use.
Abnormal phenomena such as contraction. In severe cases, it may even cause safety issues such as battery short circuits and thermal runaway, posing a threat to the life and property of users.
（4） The wave edge of the electrode can affect the effective area of the electrode and the uniformity of the electrochemical reaction, leading to a decrease in battery capacity. Meanwhile, uneven current distribution can also increase the internal resistance of the battery, reducing its power performance and energy efficiency.
Improvement measures for the wavy edges of lithium battery electrodes
（1） Using high-quality materials to increase yield stress, select materials with good mechanical properties and uniform microstructure, optimize material formulation and preparation processes to improve the yield stress and uniformity of polarizer materials, and enhance their ability to resist deformation.
（2） Strictly control the uniform thickness of battery electrodes during the electrode preparation process, using high-precision coating, rolling and other equipment and processes to monitor and adjust the thickness of electrodes in real time, ensuring that the consistency of electrode thickness is within the allowable error range.
（3） Correctly install and maintain equipment, ensure reasonable process parameters, regularly maintain and calibrate manufacturing equipment, and ensure the accuracy and stability of the equipment. At the same time, based on material characteristics and product requirements, optimize process parameters such as coating speed, drying temperature, and roll pressure to reduce the problem of wavy edges in the polarizer caused by improper processes.
（4） Adjust the coating and tension control processes to optimize the slurry flow rate, coating gap, and tension control during the coating process, ensuring that the slurry is evenly distributed on the surface of the polarizer and maintaining stress balance during the drying process. In the subsequent processing, the tension of the pole piece should be reasonably controlled to avoid deformation caused by excessive or insufficient tension.
（5） The use of hot roller technology and controlling the rolling speed can improve the physical properties and surface smoothness of the polarizer. By controlling the rolling speed and temperature, the stress accumulation and deformation of the polarizer during the rolling process can be reduced.
Detection and Control of Wave Edges in Lithium Battery Pole Plates
（1） Optical microscopy is a commonly used detection method that can visually observe the microstructure of the edge of the polarizer and preliminarily evaluate the degree and characteristics of the wavy edge. However, this method has limited detection accuracy and may be difficult to accurately identify small wave edge defects.
（2） Using digital microscope solutions to improve detection accuracy. Digital microscopes combine advanced image processing technology to provide higher magnification and clearer images, enabling more accurate detection and measurement of the size, shape, and distribution of polarizer wave edges.
（3） Set reasonable cutting parameters, such as lateral pressure and tool overlap during the cutting process, to control the deformation of the polarizer during the cutting process. At the same time, choose the appropriate bite angle, blade diameter, and sheet thickness to reduce the impact of slitting on the edge quality of the polarizer.
conclusion
The wavy edge of lithium battery electrodes is a complex but not to be ignored issue, which involves multiple aspects such as materials, equipment, and processes. The presence of wavy edges has a serious impact on the performance, lifespan, and safety of batteries. By taking effective improvement measures and strict testing and control methods, the quality of lithium battery electrodes can be significantly improved, thereby enhancing the overall performance and reliability of lithium batteries.
