Cuprous oxide-coated graphite was synthesized by a polyol reduction process and analyzed by scanning electron microscopy, charge–discharge measurements and cyclic voltammetry. Cu2O exists at the surface of graphite in the form of nanoparticles and nanorods. The coated cuprous oxide layer acts as a protective layer separating graphite from the propylene carbonate (PC)-based electrolyte solution, and greatly suppresses PC decomposition and graphite exfoliation in PC-based electrolyte systems.