In Situ Construction of Stable Tissue-Directed/Reinforced Bifunctional Separator/Protection Film on Lithium Anode for Lithium-Oxygen Batteries.

To achieve a high reversibility and long cycle life for Li-O2 battery system, the stable tissue-directed/reinforced bifunctional separator/protection film (TBF) is in situ fabricated on the surface of metallic lithium anode. It is shown that a Li-O2 cell composed of the TBF-modified lithium anodes exhibits an excellent anodic reversibility (300 cycles) and effectively improved cathodic long lifetime (106 cycles). The improvement is attributed to the ability of the TBF, which has chemical, electrochemical, and mechanical stability, to effectively prevent direct contact between the surface of the lithium anode and the highly reactive reduced oxygen species (Li2 O2 or its intermediate LiO2 ) in cell. It is believed that the protection strategy describes here can be easily extended to other next-generation high energy density batteries using metal as anode including Li-S and Na-O2 batteries.