Challenges and Opportunities in Composite Cathode Production of Polymer-Based Solid-State Batteries

Higher energy densities and a high level of safety are decisive for the energy storage systems of electric vehicles to satisfy the high range requirements. The polymer-based solid-state battery is a promising technology that stands out due to its high energy density and theoretical safety advantages. Research into this innovative battery technology in Germany and Europe mainly focuses on the laboratory scale. For the production of polymer-based solid-state batteries, there is a lack of accessible information to transfer the laboratory scale to pilot production. Therefore, competence in upscaling the polymer-based composite cathode is essential. The current work investigates the cause-effect relationships of individual production processes of the polymer-based composite cathode in order to establish an in-depth understanding of how they can be scaled. In particular, mixing, coating, and calendering are compared with the corresponding processes of the conventional electrode production of lithium-ion battery cells to identify similarities and differences. The comparison demonstrates that the calendering process is particularly challenging due to the minimization of the porosity of the polymer-based composite cathode. For this reason, the challenges of calendering are discussed in detail. An existing empirical model of the calendering of lithium metal is used to enhance the comprehension of the calendering process. This results in a reduced material consumption and experimental setup time. By using a temporary foil to protect the calender rollers from the high adhesion, polymer-based composite cathodes can be calendered with a conventional roll-to-roll process. The results provide first informations of the scalability of the process of polymer-based composite cathodes from laboratory-based work to a larger scale.