Date: 2025-11-24 hits: 101
Overview of the Coating Process
The coating process is the process in lithium battery manufacturing where electrode materials are uniformly coated onto copper or aluminum foil. The quality of this process directly affects the battery's specific energy, cycle life, and charge/discharge efficiency. The purpose of the coating process is to ensure that the electrode material forms a uniform and stable film on the substrate surface, while avoiding defects such as bubbles, cracks, or uneven coating.
The Impact of Slurry Viscosity on the Coating Process
The impact of excessively high viscosity on the coating process: When the slurry viscosity is too high, a series of problems will occur during the coating process, mainly including:
1. Uneven Coating: Slurries with excessively high viscosity have poor fluidity and cannot be uniformly coated on the substrate surface. The coating thickness may be inconsistent, leading to unstable battery performance.
2. Coating Difficulties: High-viscosity slurries increase the burden on the coating equipment during the coating process, requiring higher coating pressure or speed. This leads to accelerated wear on the equipment and may even affect its service life. Furthermore, excessively high viscosity may cause slurry blockage during the coating process, affecting production efficiency.
3. Low Coating Speed: High-viscosity slurries flow slowly during coating, making it difficult to increase the coating speed. This not only increases production time but may also lead to higher production costs. The poor flowability of high-viscosity slurries as they pass through the rollers in the coating machine causes slurry accumulation, affecting the continuity and consistency of the coating.
4. Bubble Formation: High-viscosity slurries, due to their poor flowability, often trap air bubbles in the coating. These bubbles expand during drying, leading to coating peeling or cracking.
The impact of low viscosity on the coating process:
1. Unstable coating: Low-viscosity slurries have excessive fluidity, easily causing dripping during coating, leading to unstable coatings, and even localized areas of insufficient thickness or peeling.
2. Poor coating adhesion: Low-viscosity slurries may fail to form good adhesion to the substrate surface during coating. Peeling may occur during subsequent drying.
3. Rapid evaporation: Low viscosity slurries cause solvents to evaporate easily, resulting in premature curing. This affects coating quality, especially at high-speed coating, where rapid solvent evaporation may prevent the slurry from fully dispersing on the substrate, leading to coating defects.
4. Coating machine clogging: Unlike the increased equipment load caused by high-viscosity slurries, low-viscosity slurries may cause unstable flow rates in the coating machine due to excessively rapid fluidity, resulting in clogging or uneven slurry flow. How to Control Slurry Viscosity
During the production process, controlling slurry viscosity typically requires adjusting parameters such as the solvent ratio, stirring speed, and temperature. For example, increasing the solvent ratio can reduce viscosity. Generally, the viscosity of the coating slurry should be maintained within a certain range to ensure its fluidity, guaranteeing uniform coating without flowing too quickly or becoming too viscous.
Summary
The viscosity of the lithium battery slurry directly affects the quality and efficiency of the coating process. High-viscosity slurries can lead to uneven coating, coating difficulties, and bubble formation, while low-viscosity slurries may result in unstable coatings and poor adhesion. Therefore, during production, it is necessary to precisely control the slurry viscosity, keeping it within the optimal range to ensure smooth coating and ultimately improve the overall performance of the lithium battery.
