Cuprous oxide as Cathode Catalysts of Lithium Oxygen Batteries

Cuprous oxide (Cu2O) has been acknowledged as a potential electrocatalyst for oxygen electrochemistry. However, it has been a challenge to study its oxygen reduction and evolution reactions in conventional aqueous systems as the instability of Cu2O in aqueous solution, especially in acid or alkaline solution. In the present study, self-supported Cu2O films are prepared by an electrochemical method, and used as cathode catalysts in Li-O2 batteries. The nonaqueous environment of Li-O2 batteries prevents decomposition of Cu2O and guarantees the cathode processes. Instead of traditional strategy of mixing active materials with carbons and binders, the carbon- and binder-free Cu2O films are used to prevent the interference of carbon electrocatalysis and side reactions from carbon or binders. Based on electrochemical measurements, the discharge and charge voltage of the battery on the Cu2O surface are 2.7 and 3.6 V, respectively, behaving a lower charging overpotential than traditional carbon materials. Furthermore, the X-ray photoelectron spectra (XPS) of cathodes after cycle tests indicate Cu2O catalysts is stable in Li-O2 batteries, and the battery performs 100 cycles with no evident decay. Finally, cyclic voltammetry and electrochemical impedance spectra are measured in order to study the cathode processes and the mechanism of rechargeability.