Understanding oxygen reactions in aprotic Li-O₂ batteries

Although significant progress has been made in many aspects of the emerging aprotic Li-O₂ battery system, an in-depth understanding of the oxygen reactions is still underway. The oxygen reactions occurring in the positive electrode distinguish Li-O₂ batteries from the conventional Li-ion cells and play a crucial role in the Li-O₂ cell's performance (capacity, rate capability, and cycle life). Recent advances in fundamental studies of oxygen reactions in aprotic Li-O₂ batteries are reviewed, including the reaction route, kinetics, morphological evolution of Li₂O₂, and charge transport within Li₂O₂. Prospects are also provided for future fundamental investigations of Li-O₂ chemistry.