A voltage-driven dissoluble electrolyte additive enables high-rate and ultralong-life lithium metal batteries

Abstract Developing a solid electrolyte interphase (SEI) with good stability and high Li-ion conductivity is critical for realizing high-rate and long-life lithium metal batteries (LMBs), yet still challenging. Herein, we demonstrate that adding excess m -Li 2 ZrF 6 (monoclinic structure) nanoparticles to an ordinary commercial LiPF 6 -containing carbonate electrolyte used in LMBs facilitates the slow release of ZrF 6 2- ions into the electrolyte via internal electrical field, thus creating a very stable SEI based on t -Li 2 ZrF 6 (trigonal structure) with high Li-ion conductivity. Computational and cryogenic transmission electron microscopy experimental studies revealed that the in-situ formation of t -Li 2 ZrF 6 nanocrystals in the hybrid SEI significantly enhanced Li-ion transfer and suppressed the growth of Li dendrites. As result, the LMBs assembled with LiFePO 4 cathodes (2 mAh cm −2 areal capacity), 3D Li-carbon anodes (~50 µm thick Li) and the unique electrolyte displayed greatly improved cycling stability with 80.1% capacity retention after 3000 cycles at a 1 C rate. This work identifies a new and simple strategy to impart LMBs with ultralong lifespans under practical high-rate conditions.