Surface Modification of Cathode Via Precursor Coating for All-Solid-State Batteries

Abstract

Li-ion batteries (LIBs) have been used widely for mobile device, electrical vehicle (EV), and energy storage system (ESS). As the expansion of application fields, unstable safety of LIBs attributed to the flammable organic liquid electrolyte has been considered as a serious issue. All solid state batteries (ASSBs) based on nonflammable inorganic solid electrolyte could be a good solution for this issue. Until now, a lot of inorganic ionic conductors has been studied for using as solid electrolytes of ASSBs. Sulfides are promising candidates for solid electrolyte for ASSBs due to their comparable ionic conductivity to liquid electrolyte. Moreover, they can be easily assembled with electrodes due to their ductility. However, ASSBs based on sulfide electrolyte has several problems such as poor rate capability and unstable cyclic performance, which are mainly attributed to the side reaction between oxide cathodes and reactive sulfide electrolyte. Surface modification of cathode using stable materials against sulfides has been known as an effective approach for overcoming this problem. In this study, the cathode material was modified using several oxides. Specially, the coating process was started from the precursors instead of as-prepared cathodes to obtain more homogeneous coating layer. The surface modified cathodes are expected to show improved cyclic performance and rate capability due to the effect of surface modification.