Facilitating the Oxygen Evolution Reaction of Lithium Peroxide via Molecular Adsorption

A major obstacle to developing practical Li-O-2 battery is the inefficient oxygen evolution reaction (OER) of lithium peroxide Li2O2, as the high energy barrier associated with the OER process causes low round-trip efficiency. In a real battery system, many kinds of additives and impurities exist in the electrolyte, and therefore, molecular adsorptions on the Li2O2 surface are unavoidable; nevertheless, their influences on the OER of Li2O2 are rarely understood. Herein, density functional theory (DFT) calculations are employed to simulate the OER of Li2O2 surface adsorbed with a single H2O molecule. Simulation results indicate that the H2O molecule can spontaneously adsorb on the Li2O2 surface during the whole OER process. Consequently, the energy barriers of OER on Li2O2 surface are decreased and thus the intrinsic overpotential of the Li-O-2 battery is reduced. Our findings suggest that the OER process in a Li-O-2 battery can be modified by controlling the electrolyte additives, providing a new strategy for the development of improved Li-O-2 batteries.