Although a significant reduction in costs has been achieved in recent years in Li-Ion battery technology through economies of scale, reducing manufacturing costs remains a central and mission-critical development goal. Within the research project OptiEx – Optimized Manufacturing Processes for High-Load Electrodes based on Extrusion Processes – this decisive aspect of cost reduction is realized by an innovative, resource-saving process for electrode manufacturing, which requires significantly lower amounts of solvents (<80%) and also allows lower energy requirements (approx. <50%) for drying the highly viscous battery suspensions.
A major project goal is the setup and test operation of a pilot plant for coupled compound and film extrusion for current anode and cathode materials and further investigations of process structure properties. This plant will be used for the continuous production of high-capacity electrode films and for scaling up the laboratory process from the ProZell pre-project HiLo. For this purpose, the pilot plant will combine the sub-processes mixing/dispersing, coating, drying and winding. In order to achieve a stable plant operation with competitive coating speeds, and thus to achieve the targeted TRL 5, certain aspects will be addressed and optimized. This includes dosing of the materials, direct coating of the pastes on the current collector or reproducible layer shape with sufficient layer thickness via slot die application. For this purpose, the process development is accompanied by rheological analyses and specific adaptions (e.g. using additives) of the electrode pastes to tailor the shear thinning, partly viscoelastic flow behavior of the pastes in the best possible way.
The process development is supported by a model-based design of the electrodes at the TUD. By optimizing the electrode design, the energy and power density of full cells is maximized in an application-specific way and the corresponding design parameters are determined. Analytical models with reduced complexity and high practical relevance shall be developed for straightforward application as a process accompanying tool by users/technicians. Within the scope of the project, blended and multilayer electrodes will be addressed and validated, which represent an extension of the degrees of freedom in electrode design and can be implemented comparatively easily in the extrusion process using highly viscous pastes.