Li-air batteries: air stability of lithium metal anodes

Aprotic rechargeable lithium-air batteries (LABs) with an ultrahigh theoretical energy density (3,500 Wh kg(-1)) are known as the 'holy grail' of energy storage systems and could replace Li-ion batteries as the next-generation high-capacity batteries if a practical device could be realized. However, only a few researches focus on the battery performance and reactions in the ambient air environment, which is a major obstacle to promote the practical application of LABs. Here, we have summarized the recent research progress on LABs, especially with respect to the Li metal anodes. The chemical and electrochemical deteriorations of the Li metal anode under the ambient air are discussed in detail, and the parasitic reactions involving the cathode and electrolyte during the charge-discharge processes are included. We also provide stability perspectives on protecting the Li metal anodes and propose design principles for realizing high-performance LABs.