Electrode–solid electrolyte composite materials for all-solid-state lithium batteries were prepared by coating of the Li2S–P2S5 solid electrolyte onto LiCoO2 particles using a N-methylformamide (NMF) solution of 80Li2S·20P2S5 (mol%) solid electrolyte. SEM and EDX analysis showed that the Li2S–P2S5 solid electrolyte was uniformly coated on LiCoO2 particles. The all-solid-state cell using the LiCoO2 particles coated with the solid electrolyte showed higher charge–discharge capacity than the cells using uncoated LiCoO2 particles.