Navigating Solvent Chemistry and Microstructures: Toward Mechanically Enhanced Ceramic-Rich Composite Electrolytes

Ultrathin ceramic-rich solid composite electrolytes provide a safer and potentially higher energy density alternative to liquid electrolytes used in today's lithium-ion batteries. Producing ultrathin composites with ceramic-like ionic conductivity requires the incorporation of a polymeric binder for enhanced ductility. In this Perspective, we discuss two key aspects that must be considered when designing composite electrolytes: (1) the mechanical properties of the composite and their correlation with the ceramic and polymer microstructure and (2) the chemistry between the ceramic electrolytes, polymers, and solvents used to process the composites. We highlight the importance of understanding (1) the ceramic structure, crystallinity, and particle size upon solvent processing and (2) the ceramic/polymer interface chemistry and its correlation with the microstructure of the composites. We present opportunities in fabricating ultrathin support structures for composites, optimizing ceramic particle packing parameters, and routes toward mechanically enhanced, compact, composite-based solid electrolytes.