CoMn2O4 Spinel Nanoparticles Grown on Graphene as Bifunctional Catalyst for Lithium-Air Batteries

Positive electrodes for the oxygen reduction reaction (ORR) and the oxygen-evolution reaction (OER) play a critical role in fuel cells and metal-air batteries. Tetragonal CoMn2O4 spinel nanoparticles have been grown on the surface of graphene sheets (CMOG) via a two-step synthesis. The ORR/OER catalytic characteristics of CMOG were studied with a rotating-disk electrode. Also a lithium-air primary cell having a non-aqueous electrolyte and a rechargeable lithium-air cell with a Li-ion solid electrolyte separating a non-aqueous anode electrolyte from an alkaline aqueous cathode electrolyte were assembled with a CMOG cathode and tested. The results indicate that a CMOG cathode can provide a catalytic platform of considerable activity for the ORR in both electrolytes and also for the OER in the aqueous electrolyte.