A new methodology for evaluating the performances of electrocatalysts for rechargeable Li-O2 batteries: (Ru-Sn)O2@graphene nanowalls/Ti electrodes as an example

Abstract The bi-functional activities of electrocatalysts for the oxygen reduction reaction (ORR) and discharge products decomposition in the typical organic electrolyte of rechargeable Li-O2 batteries are proposed to be effectively evaluated by cyclic voltammetry (CV) with varying the lower potential limit. The free-standing Ru-Sn oxides-decorated graphene nanowalls are employed as examples to demonstrate this interesting methodology. Both Ru-enriched and Sn-enriched Ru-Sn oxides (RTO73 and RTO37) show higher bi-functional activities than two mono-oxides and pure graphene from CV and confirmed by the charge-discharge results. The full cell performances such as rate capability, cycle life and charge-discharge voltage gaps can be correlated to the findings from CV.