Fluorinated electrolyte formulations design enabling high-voltage and long-life lithium metal batteries

The poor compatibility of carbonate-based electrolytes with lithium metal anodes results in unstable solid
electrolyte interphase, leading to lithium dendrite formation, low Coulombic efficiency, and short cycle life. To
address this issue, we propose a novel fluorinated electrolyte that leverages lithium bis(fluorosulfonyl)imide
(LiFSI), along with fluorinated solvents. An extremely low concentration of lithium nitrate exerts a substantial
impact on the Li ion solvation structure, inducing an anions-rich solvation structure, results in an inorganic-rich
electrolyte interphase layer mainly composed of Li3N and LiF, which effectively inhibits lithium dendrite for-
mation, enhances the interfacial stability between the electrode and electrolyte, and yields excellent cycling
performance in lithium metal batteries. When coupled with a high nickel content cathode (LiNi0.8Co0.1Mn0.1O2),
the cells exhibit impressive cycling performance with 1000 cycles at 4 C, retaining 68.6 % capacity (with charge
times under 15 min). Despite the relatively low oxidation stability of Dimethoxyethane in the electrolyte, the cell
demonstrates exceptional high-voltage electrochemical performance, even up to 4.5 V, the cells do not show
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extensive electrolyte decomposition and structural changes, preserving 79.2 % capacity retention after 300 cy-
cles. Using 50 μm lithium foil in the cells, remarkable capacity retention of 89.5 % is achieved after 400 cycles at
1 C. This remarkable compatibility between the anode and cathode represents a significant breakthrough in
enhancing the reliability and performance of lithium metal batteries.