Lowering the charge voltage of Li-O₂ batteries: Via an unmediated photoelectrochemical oxidation approach

We here demonstrate an unmediated photoelectrochemical oxidation approach to address the overpotential issue of Li-O₂ batteries during the charge process. We show that photoexcited holes from the photoelectrode provide a direct oxidation of solid Li₂O₂, without the use of a redox mediator. The Li-O₂ battery composed of carbon nitride on carbon paper as a cathode and also as a photoelectrode exhibits an ultralow charge voltage of 1.96 V resulting in a 'negative' overpotential and good cycling performance. These results could represent a new and promising avenue for the future development of photo-charging all-solid-state batteries.