Cathode Processing Optimization Toward Solid‐State Batteries with Monolithic Oxysulfide Glassy Solid Electrolytes

Seeking to further the development of all‐solid‐state lithium‐ion batteries (ASSLIBs), an optimized composite cathode blend for lithium‐ion batteries (LIBs) is fabricated via planetary ball mill using LiFePO 4 , a mixed oxysulfide (MOS) glassy solid electrolyte (GSE), called LiSiPSO, a carbon additive, and styrene‐butadiene rubber binder. The ionic and electronic conductivities of the composite cathode are evaluated using electrochemical impedance spectroscopy (EIS). Using EIS measurements, the milling time and processing order of forming the composite mixture are modified to improve these transport properties. By tailoring the processing methods used to create the composite cathode, ASSLIBs fabricated with optimized cathodes in conjunction with a monolithic GSE display good specific capacities (100 mAh g − 1 initial) and coulombic efficiencies (>95%) at room temperature, demonstrating the viability of monolithic MOS GSEs in ASSLIBs. Cyclic voltammetry, galvanostatic cycling with potential limits, and postmortem Raman spectroscopy reveal an irreversible reaction and growing instability within the cycled cells, meriting further research to produce LIBs with higher capacities and longer cycle lives through the development of more stable GSEs.