Optimization of Edge Quality in the Slot‐Die Coating Process of High‐Capacity Lithium‐Ion Battery Electrodes

Abstract

Understanding and reducing edge elevations at the lateral edges are crucial aspects to reduce reject rates during electrode production for lithium‐ion batteries (LIB). Herein, different process conditions to reduce edge elevations at the lateral edges of water‐based, shear‐thinning coatings in the production of LIB electrodes are presented. The reduction of edge elevations is transferred from state‐of‐the‐art electrodes to high‐capacity electrodes. The developed process configuration greatly reduces reject caused by cutting off the edge areas in the industrial roll‐to‐roll process for electrode production. Compared with state‐of‐the art electrodes, the reject rate for high‐capacity electrode production is significantly higher because the edge geometry in crossweb direction of the electrodes is wider. An optimization can be achieved by a combined adjustment of the coating gap and the slot‐die angle to the substrate (angle of attack) to affect the pressure field in the coating bead. Therefore, a systematic investigation and optimization of these process parameters are presented. In addition, the investigation of the process stability of the coating is required. Based on this optimization, a reduction of edge elevations for high‐capacity electrode coatings (5 mAh cm−2) of 69% and ultrathick high‐capacity electrode coatings (7 mAh cm−2) of 48% is possible.