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 Li 3 N and LiF, which effectively inhibits lithium dendrite formation, 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 (LiNi 0.8 Co 0.1 Mn 0.1 O 2 ), 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 extensive electrolyte decomposition and structural changes, preserving 79.2 % capacity retention after 300 cycles. 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.