Physical and Electrolytic Properties of Partially Fluorinated Organic Solvents and Its Application to Secondary Lithium Batteries: Partially Fluorinated Dialkoxyethanes

This paper investigated the physical and electrolytic properties, and charge-discharge characteristics for secondary lithium batteries of partially fluorinated 1-ethoxy-2-methoxyethane (EME) and 1,2-diethoxyethane (DEE) derivatives newly synthesized by us. Dielectric constants of fluorinated EME and DEE derivatives are almost independent of the number of fluorine atom. Viscosities of the fluorinated derivatives with three fluorine atoms are not affected by the molecular weights of them. Donor numbers of the fluorinated derivatives were estimated by 29Si NMR chemical shifts of triphenylsilanol. Conductivities of the fluorinated derivatives are dependent on the donor numbers of them. Oxidative decomposition voltages tend to increase with increasing the number of fluorine atom. EC-based equimolar binary derivative solutions with three fluorine atoms show higher lithium electrode cycling efficiencies. In general, EC-based fluorinated EME and DEE derivative solutions show higher discharge capacities and cycling efficiencies for Li | LiCoO2 cells.