In Situ Grazing Incidence Surface X-ray Diffraction Study of Li2O Ultra-thin Film Formation on Li and Its Effect of Suppressing Dendrite Formation during Charging and Discharging

When a Li film deposited on a Ni(111) single-crystal was immersed in three kinds of electrolyte solutions, a uniform Li2O ultra-thin film was formed only in the O2-saturated tetraglyme solution containing 1 M LiNO3 and 50 mM LiBr. It was clarified by an in situ grazing incidence surface X-ray diffraction measurement. We found that this Li2O ultra-thin film stably exists during an electrochemically dissolution/deposition reaction, i.e., discharging/charging cycles at the anode of the Li-O2 battery, and effectively suppresses dendrite formation.