Incorporation of Ionic Conductive Polymers into Sulfide Electrolyte‐Based Solid‐State Batteries to Enhance Electrochemical Stability and Cycle Life

Sulfide‐based inorganic solid electrolytes are promising materials for high‐performance safe solid‐state batteries. The high ion conductivity, mechanical characteristics, and good processability of sulfide‐based inorganic solid electrolytes are desirable properties for realizing high‐performance safe solid‐state batteries by replacing conventional liquid electrolytes. However, the low chemical and electrochemical stability of sulfide‐based inorganic solid electrolytes hinder the commercialization of sulfide‐based safe solid‐state batteries. Particularly, the instability of sulfide‐based inorganic solid electrolytes is intensified in the cathode, comprising various materials. In this study, carbonate‐based ionic conductive polymers are introduced to the cathode to protect cathode materials and suppress the reactivity of sulfide electrolytes. Several instruments, including electrochemical spectroscopy, X‐ray photoelectron spectroscopy, and scanning electron microscopy, confirm the chemical and electrochemical stability of the polymer electrolytes in contact with sulfide‐based inorganic solid electrolytes. Sulfide‐based solid‐state cells show stable electrochemical performance over 100 cycles when the ionic conductive polymers were applied to the cathode.