V2C MXene enriched with -O termination as high-efficiency electrocatalyst for lithium-oxygen battery

Lithium-oxygen (Li-O2) battery is known as the most promising next generation energy storage device due to its ultrahigh theoretical energy density. Developing high-efficiency electrocatalyst is the key to reduce the overpotential and improve the energy efficiency of Li-O2 battery. In this work, catalytic activity of V2C MXene with -O termination (V2CO2) towards oxygen redox reactions in Li-O2 battery is studied. Density functional theory (DFT) calculations verify that the -O termination can effectively lower the reaction barrier, optimize the adsorption of reactants on V2CO2, thus boosting the kinetics of oxygen electrode reactions. Specifically, at the current density of 100 mA g−1, V2CO2 based Li-O2 battery delivers a high capacity of 8577.3 mAh g−1 and a long-term cycling stability of 302 cycles. These findings provide a way to regulate the surface functional groups of MXene to enhance its electrocatalytic activity towards oxygen redox reactions in Li-O2 batteries.