Towards efficient ramp-up: A material-guided parameterization and process control setup for electrode calendering

The demand for lithium-ion batteries continues to rise as industries pursue electrification and emission-free production. However, battery manufacturing remains a complex and resource-intensive process involving an iterative optimization of both processes and products. Due to material costs accounting for a large proportion of the total cost of battery cell production, scrap generated during process ramp-up represents a key economic challenge. Calendering, a crucial step during electrode manufacturing, significantly impacts the mechanical and electrochemical characteristics of lithium-ion battery cells. The configuration of the calendering process remains predominantly guided by empirical tuning and trial-and-error approaches, resulting in inefficiencies during ramp-up. This highlights the need for efficient parameterization and process control strategies in electrode production, enabling faster process stabilization and minimizing scrap during the initial production phases. To address these challenges, this study proposes a material-guided process control approach for calendering. Using an in-line thickness measurement and a stepwise compaction strategy, a control model and an automated, material-dependent parameterization routine are derived. To precisely control the thickness of the electrode, the presented approach utilizes a predictive feedforward control to adjust the roll gap, complemented by a closedloop correction during calendering. The proposed approach is demonstrated on graphite anodes at various web speeds and transferred to cathode calendering. The findings show that the developed methodology allows for a streamlined ramp-up process for novel electrode formulations, thereby reducing process setup time, and material scrap. This contributes to the enhancement of cost efficiency, overall productivity, and sustainability in battery manufacturing.