Study on coating uniformity in lithium-ion battery electrode slot-die coating based on three-dimensional simulation

Abstract

Slot-die coating technology, as a critical process in lithium-ion battery electrode manufacturing, holds significant importance for the production of high-performance batteries. However, controlling the surface uniformity of the thin film has consistently been a bottleneck in this field. This study employs three-dimensional flow field simulation technology to conduct an in-depth investigation into the lithium battery coating process, aiming to elucidate the influence mechanisms of coating speed and coating gap on coating uniformity. By constructing the coating window using the capillary number (Ca) and the dimensionless gap (H*), this research found that a capillary number ranging from 0.5 to 3, combined with a dimensionless gap between 0.675 and 0.85, ensures stable coating operation. Within the suitable coating window range, by regulating the coating speed to stabilize the upstream meniscus at the center of the upper die lip, the surface uniformity of the thin film can be effectively enhanced. Furthermore, increasing the coating gap can also improve the uniformity of the thin film.