Attenuating reductive decomposition of fluorinated electrolytes for high-voltage lithium metal batteries

Fluoride-based electrolyte exhibits extraordinarily high oxidative stability in high-voltage lithium metal batteries (h-LMBs) due to the inherent low highest occupied molecular orbital (HOMO) of fluorinated solvents. However, such fascinating properties do not bring long-term cyclability of h-LMBs. One of critical challenges is the interface instability in contacting with the Li metal anode, as fluorinated solvents are highly susceptible to exceptionally reductive metallic Li attributed to its low lowest unoccupied molecular orbital (LUMO), which leads to significant consumption of the fluorinated components upon cycling. Herein, attenuating reductive decomposition of fluorinated electrolytes is proposed to circumvent rapid electrolyte consumption. Specifically, the vinylene carbonate (VC) is selected to tame the reduction decomposition by preferentially forming protective layer on the Li anode. This work, experimentally and computationally, demonstrates the importance of pre-passivation of Li metal anodes at high voltage to attenuate the decomposition of fluoroethylene carbonate (FEC). It is expected to enrich the understanding of how VC attenuate the reactivity of FEC, thereby extending the cycle life of fluorinated electrolytes in high-voltage Li-metal batteries.