LiZrF-based electrolytes for durable lithium metal batteries.

Lithium (Li) metal batteries (LMBs) are promising for high-energy-density rechargeable batteries. However, Li dendrites formed by the reaction between highly active Li and non-aqueous electrolytes lead to safety concerns and rapid capacity decay. Developing a reliable solid-electrolyte interphase is critical for realizing high-rate and long-life LMBs, but remains technically challenging. Here we demonstrate that adding excess m-LiZrF (monoclinic) nanoparticles to a commercial LiPF-containing carbonate electrolyte of LMBs facilitates the release of abundant ZrF ions into the electrolyte driven by the applied voltage, converting to t-LiZrF (trigonal) and creating a stable solid-electrolyte interphase in situ with high Li-ion conductivity. Computational and cryogenic transmission electron microscopy studies revealed that the in situ formation of the t-LiZrF-rich solid-electrolyte interphase markedly enhanced Li-ion transfer and suppressed the growth of Li dendrites. As a result, LMBs assembled with LiFePO cathodes (areal loading, 1.8/2.2 mAh cm), three-dimensional Li-carbon anodes (50-µm-thick Li) and LiZrF-based electrolyte displayed greatly improved cycling stability with high capacity retention (>80.0%) after 3,000 cycles (1C/2C rate). This achievement represents leading performance and, thus, delivers a reliable LiZrF-based electrolyte for durable LMBs under practical high-rate conditions.