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

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.