Lithium (Li) cycling efficiency by Li half cell tests and conductivity dependency on temperature are examined for LiAsF6-ethylene carbonate (EC)/2-methyltetrahydrofuran(2MeTHF)/third solvent (TS) ternary mixed solvent electrolytes, to obtain organic electrolyte systems with higher conductivity than EC/2MeTHF and with high Li cycling efficiency. The TSs used here are two chain-structured esters (methyl acetate and methyl formate), acetonitrile and five ethers, such as tetrahydrofuran (THF) and 4-methyl-1,3-dioxolane. Also, the electrolyte properties of nine Li-salts, such as LiPF6 and LiTaF6, are examined in EC/2MeTHF as alternatives to LiAsF6. As a result, the EC/2MeTHF/THF ternary system is found to be a potential candidate with which to achieve the purpose of this work. it has a 1.5 times higher conductivity of 14.2 mS cm(-1) at 25 degrees C and 5.7 mS cm(-1) at -20 degrees C than EC/2MeTHF, and its Li cycling efficiency of 96.1% is closest to that of EC/2MeTHF (96.6%).