Physical and Electrochemical Properties of Trifluorinated Linear Ether as Solvent for Lithium Secondary Batteries

Abstract

A trifluoromethyl group (CF3-) is a strong electron-withdrawing substituent. We have synthesized 1-(2,2,2-trifluoroethoxy)-2-(2-methoxyethoxy)ethane (TFEMEE). The relative permittivity, viscosity, and anodic stability of TFEMEE were higher than those of 1-ethoxy-2-(2-methoxyethoxy)ethane (EMEE). The presence of the trifluomethyl group can weaken the attractive forces between molecules. The kinematic viscosity of TFEMEE was as low as that of EMEE especially at high temperatures. The use of TFEMEE as a co-solvent greatly improved cycling efficiency of a lithium anode.