Non‐Fluorinated Cyclic Ether‐Based Electrolyte with Quasi‐Conjugate Effect for High‐Performance Lithium Metal Batteries

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AbstractFluorinated ether‐based electrolytes are commonly employed in lithium metal batteries (LMBs) to attenuate the coordination ability of ether solvents with Li+ and induce inorganic‐rich interphase, whereas fluorination inevitably introduces exorbitant production expenses and environmental anxieties. Herein, a non‐fluorinated molecular design strategy has been conceptualized by incorporating methoxy as an electron‐donating group to generate a quasi‐conjugate effect for tuning the affinity of Li+‐solvent, thereby enabling the cyclic ether solvent 2‐methoxy‐1,3‐dioxolane with weak solvation ability and exceptional Li metal‐compatibility. Accordingly, the optimized electrolyte exhibits anion‐dominant solvation structure for inorganic‐rich interphase and fulfills an impressive Li plating/stripping Coulombic efficiency of 99.6 %. As‐fabricated Li||LiFePO4 full cells with limited Li (N/P=2.5) showcase a high capacity retention of 83 % after 150 cycles, indicating excellent cycling stability. Moreover, the full LMBs demonstrate exceptional tolerance towards a wide temperature range from −20 °C to 60 °C, displaying a remarkable capacity retention of 90 % after 110 cycles at −20 °C. Such a molecular design strategy offers a promising avenue for electrolyte engineering beyond fluorination in order to cultivate high‐performance LMBs.