Rechargeable Li–O2 batteries with a covalently coupled MnCo2O4–graphene hybrid as an oxygen cathode catalyst

We employ a MnCo2O4–graphene hybrid material as the cathode catalyst for Li–O2 batteries with a non-aqueous electrolyte. The hybrid is synthesized by direct nucleation and growth of MnCo2O4 nanoparticles on reduced graphene oxide, which controls the morphology, size and distribution of the oxide nanoparticles and renders strong covalent coupling between the oxide nanoparticles and the electrically conducting graphene substrate. The inherited excellent catalytic activity of the hybrid leads to lower overpotentials and longer cycle lives of Li–O2 cells than other catalysts including noble metals such as platinum. We also study the relationships between the charging–discharging performance of Li–O2 cells and the oxygen reduction and oxygen evolution activity of catalysts in both aqueous and non-aqueous solutions.