Integrated Ring-Chain Design of a New Fluorinated Ether Solvent for High-Voltage Lithium-Metal Batteries

Ether-based electrolytes offer promising features such as high lithium-ion solvation power and stable interface, yet their limited oxidation stability impedes application in high-voltage Li-metal batteries (LMBs). Whereas the fluorination of the ether backbone improves the oxidative stability, the resulting solvents lose their Li⁺-solvation ability. Therefore, the rational molecular design of solvents is essential to combine high redox stability with good ionic conductivity. Here, we report the synthesis of a new high-voltage fluorinated ether solvent through integrated ring-chain molecular design, which can be used as a single solvent while retaining high-voltage stability. The controlled Li⁺-solvation environment even at low-salt-concentration (1 M or 2 M) enables a uniform and compact Li anode and an outstanding cycling stability in the Li|NCM811 full cell (20 μm Li foil, N/P ratio of 4). These results show the impact of molecular design of electrolytes towards the utilization of LMBs.