A Long-Life Lithium-Air Battery in Ambient Air with a Polymer Electrolyte Containing a Redox Mediator.

Lithium-air batteries when operated in ambient air generally exhibit poor reversibility and cyclability, because of the Li passivation and Li2 O2 /LiOH/Li2 CO3 accumulation in the air electrode. Herein, we present a Li-air battery supported by a polymer electrolyte containing 0.05 m LiI, in which the polymer electrolyte efficiently alleviates the Li passivation induced by attacking air. Furthermore, it is demonstrated that I- /I2 conversion in polymer electrolyte acts as a redox mediator that facilitates electrochemical decomposition of the discharge products during recharge process. As a result, the Li-air battery can be stably cycled 400 times in ambient air (relative humidity of 15 %), which is much better than previous reports. The achievement offers a hope to develop the Li-air battery that can be operated in ambient air.