  The rechargeable aprotic Li-air (O2) battery is a promising potential
technology for next generation energy storage, but its practical realization
still faces many challenges. In contrast to the standard Li-O2 cells, which
cycle via the formation of Li2O2, we use a reduced graphene oxide electrode,
the additive LiI, and the solvent dimethoxyethane to reversibly form/remove
crystalline LiOH with particle sizes > 15 um during discharge/charge. This
leads to high specific capacities, excellent energy efficiency (93.2%) with a
voltage gap of only 0.2 V, and impressive rechargeability. The cells tolerate
high concentrations of water, water being the dominant proton source for the
LiOH; together with LiI it has a decisive impact on the chemical nature of the
discharge product and battery performance.
