Advanced materials for rechargeable lithium-oxygen batteries and zinc-air batteries

Metal air batteries, including lithium-oxygen (Li-O2) and zinc air batteries (ZAB), have drawn research attention around the world due to their superior high energy densities. A Li-O2 cell discharges to Li2O2 product at 3.1 V and could deliver a specific energy as high as 3623 Wh/kg, which makes it a possible candidate system to power a full-size electric car. Up to now, the challenges of metal air batteries have been the cycling instability of electrolytes and their low round–trip efficiency, which could be increased by optimizing the cathode catalysts and structures. In the past ten years, many advances have been achieved, but the challenges remain.