The Salt Matters: Enhanced Reversibility of Li-O-2 Batteries with a Li[(CF3SO2)(n-C4F9SO2)N]-Based Electrolyte

The safety hazards and cycle instability of lithium metal anodes (LMA) constitute significant barriers to progress in lithium metal batteries. This situation is worse in Li-O-2 batteries because the LMA is prone to be chemically attacked by O-2 shuttled from the cathode. Notwithstanding, efforts on LMA are much sparse than those on the cathode in the realm of Li-O-2 batteries. Here, a novel lithium salt of Li[(CF3SO2)(n-C4F9SO2)N] (LiTNFSI) is reported, which can effectively suppress the parasitic side reactions and dendrite growth of LMA during cycling and thereby significantly enhance the overall reversibility of Li-O-2 batteries. A variety of advanced research tools are employed to scrutinize the working principles of the LiTNFSI salt. It is revealed that a stable, uniform, and O-2-resistive solid electrolyte interphase is formed on LMA, and hence the cross-talk between the LMA and O-2 shuttled from the cathode is remarkably inhibited in LiTNFSI-based Li-O-2 batteries.