Application to lithium batteries of ternary solvent electrolytes with ethylene carbonate-1,2-dimethoxyethanemixture

摘要

The electrolytic conductivity, the ithium cycling efficnecy of ithium electrode and the energy density for Li/V_2O_5(2025) coin-type cell were examined in ternnary solvent electrolytes containing LiPF_6 and LiClO_4 with ethylene carbonate (EC)-1,2-dimethoxyethaneDME) equimolar binary mixture at 25 deg C. The solvents applied to EC-DME mixture are dimethyl carbonate(DMC), ethyl methyl carbonate(EMC), dietyl carbonate(DEC), 1,3-dioxolane(DOL), 2, 2-bis(trifluoromethyl)-1, 3-dioxolane(TFMOL), 1,3-dimethyl-2-imidazolidinone(DMI) and 1-methyl-2-pyrrolidinone(NMP). The order of decrease of the molar conductivities in ternary solvents electrolytes except DMI and NMP systems is agreement with that of increase in viscosities of the olvents applied to EC-DME binary mixture. The molar conductivities in ternary solvent electrolytes containing DMI and NMP are mainly affected by the dielectric constants rather than viscosities of mixed solvents. The energy density of Li/V_2O_5(2025) coin-type cell in PiPF_6/EC-DME-DOL electrolyte with the highest molar conductivity was 500 Wh kg~(-1), which is the highest value in every gernary electrolyte. The lithium cycling efficiency(charge-discharge coulombic cycling efficiency of lithium electrode) in EC-DME-EMC, EC-DME-DMI and EC-DME-TFMDOL electrolytes containing LiPF_6 is more than 75