Cyclopentylmethyl Ether, a Non-Fluorinated, Weakly Solvating and Wide Temperature Solvent for High-Performance Lithium Metal Battery

Abstract

While recent work demonstrates the advantages of weakly solvating solvents in enhancing the cyclability of LMBs, both new designs and design strategies for high performance weakly solvating solvent, especially physicochemical properties, are still lacking. Here, we propose a molecular design to tune the solvating power and physicochemical properties of non-fluorinated ether solvent. The resulting cyclopentylmethyl ether (CPME) have a weak solvating power and wide liquid-phase temperature range. By optimizing the salt concentration, the CE is further promoted to 99.4 %. Besides, the improved electrochemical performance of Li−S battery in CPME-based electrolytes is obtained at −20 °C. The Li||LFP (17.6 mg cm−2) battery with developed electrolyte maintains >90 % of the original capacity over 400 cycles. Our design concept for solvent molecule provides a promising pathway to non-fluorinated electrolytes with weakly solvating power and wide temperature window for high-energy-density LMBs.