The Salt Matters: Enhanced Reversibility of Li–O₂ Batteries with a Li[(CF₃SO₂)(<i>n</i>‐C₄F₉SO₂)N]‐Based Electrolyte

Abstract

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-O₂ batteries because the LMA is prone to be chemically attacked by O₂ shuttled from the cathode. Notwithstanding, efforts on LMA are much sparse than those on the cathode in the realm of Li-O₂ batteries. Here, a novel lithium salt of Li[(CF₃ SO₂ )(n-C₄ F₉ SO₂ )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-O₂ 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 O₂ -resistive solid electrolyte interphase is formed on LMA, and hence the "cross-talk" between the LMA and O₂ shuttled from the cathode is remarkably inhibited in LiTNFSI-based Li-O₂ batteries.