Production of Sulfidic Cylindrical All-Solid-State Batteries

All-solid-state batteries promise higher energy densities than conventional liquid electrolyte lithium-ion batteries. This new battery technology is demonstrated in the pouch design with flat electrodes and solid electrolytes. However, pouch design requires an external compression system, such as springs, reducing energy density at the battery pack level. This challenges the scale-up of this new technology. In contrast, a cylindrical cell housing design, used in lithium-ion battery batteries, ensures a high operational pressure through its hard case. Adapting the new all-solid-state technology to the cylindrical design would increase energy density at the battery pack level. Nevertheless, the cylindrical design necessitates windable and ionic conductive solid composite electrodes and solid electrolytes, which have yet to be developed. This work proposes potential solutions to produce a sulfidic cylindrical all-solid-state battery. Through literature review and BMW experience, we first described the state-of-art of both technologies. Subsequently, we compared them and identified three major technical obstacles. First, the roll-to-roll process must replace the current discontinuous manufacturing process. Herein, we proposed the calendering process to replace uniaxial pressing. Secondly, the high pressure required for ionic conductivity makes the solid composite electrodes and the solid-electrolyte separator brittle. This fact difficulties their windability. A production balance between ionic conductivity and mechanical flexibility needs to be found. Third, the cylindrical cell housing must provide the operational pressure given the missing springs. Pre-warming the cell housing and using a dynamic cell core might be solutions. This work provides researchers and industry with a concrete approach for cost-effective scaling of all-solid-state batteries.