Graphene/doped ceria nano-blend for catalytic oxygen reduction in non-aqueous lithium-oxygen batteries

An important component in lithium-air batteries is the oxygen electrode, which facilitates the oxygen reduction reaction during the discharge process and the oxidation reaction of Li2O2 during the charge process. The performance of the oxygen electrode strongly depends upon the activity of the materials employed. Herein, we report the catalytic activity of the graphene/zirconium doped ceria (ZDC) nanoblend prepared by mixing graphene, which is prepared using the modified Hummers method followed by H-2 reduction, and ZDC, chemically prepared. With merely 10% loading of ZDC on the graphene, Li-O-2 cells showed a threefold increase in their discharge capacities. The well exfoliated layered structure of graphene and the mesoporous structure of ZDC facilitated the diffusion of the electrolyte and oxygen in the inner electrode to enhance the catalytic efficiency and also offered ample volume for the accumulation of discharge product. The synergistic effect of the fast kinetics of electron transport provided by the graphene support and the high electro-catalytic activity provided by the ZDC resulted in the excellent performance of the oxygen electrode in the Li-O-2 batteries. (C) 2013 Elsevier Ltd. All rights reserved.