Reducing the charging voltage of a Li-O₂ battery to 1.9 v by incorporating a photocatalyst

We here present a photoassisted rechargeable Li-O₂ battery by integrating a g-C₃N₄ photocatalyst to address the overpotential issue of conventional non-aqueous Li-O₂ batteries. The high charging overpotential of a Li-O₂ battery is compensated by the photovoltage, and finally an ultralow charging voltage of 1.9 V is achieved, which is much lower than that of any other conventional non-aqueous Li-O₂ batteries. It is also worth noting that the charging voltage is even much lower than the discharging voltage (∼2.7 V), resulting in 142% energy efficiency (output electric energy/input electric energy, not including solar energy).