In order to improve low-temperature performance of ethylene carbonate (EC) + tetrahydropyran (THP) (5:5) electrolyte with 1 mol dm(-3) lithium bisperfluoroethylsulfonyl imide (LiN(SO2C2F5)(3) as solute, propylene carbonate (PC) solvent was mixed with this electrolyte. It was found that the electrochemical properties of the resultant ternary electrolytes depended strongly on the solvent composition and 1 mol dm(-3) (LiN(SO2C2F5)(2))/EC + PC + THP (3:3:4) electrolyte had not only promising freezing point of -36 degreesC but also high lithium cycling efficiency of 95.2%. Furthermore, lithium cycling efficiency was improved to 99.0% by decreasing lithium deposition current density to 0.2 mA cm(-2). At the temperature ranging from 25 to -10 degreesC, Li/LiMn2O4 coin cell with 1 mol dm(-3) (LiN(SO2C2F5)(2))/ EC + PC + THP (3:3:4) electrolyte showed the satisfactory cycling performance. Thermal tests further disclosed that this ternary electrolyte showed good thermal stability even with the existence of lithium metal. (C) 2001 Elsevier Science Ltd. All rights reserved.