Lithium imide electrolytes with two-oxygen-atom-containing cycloalkane solvents for 4 V lithium metal rechargeable batteries

Lithium bisperfluoroethylsulfonyl imide (LiN(SO2C2F5)(2)) electrolytes with five-, six-, and seven-membered cycloalkane solvents containing two oxygen atoms were characterized in order to develop the organic electrolytes for 4 V lithium metal rechargeable batteries. Among the examined electrolytes, ethylene carbonate (EC) and 1,3-dioxane (DOX) mixed electrolyte (5:5) with 1 mol/dm(3) LiN(SO2C2F5)(2) as solute were found to be the most advantageous, with high cycling efficiency (95.2%), good oxidation stability (>5 V), promising freezing point (- 21 degrees C), and high boiling point (105 degrees C) of DOX solvent. Furthermore, only a slight decline in discharge capacity was observed for a Li/LiMn2O4 coin cell with this electrolyte. Lithium cycling efficiency was also found to increase with decreasing deposition current density. Especially at deposition/dissolution current density of 0.3/0.6 mA/cm(2), lithium cycling efficiency in 1 mol/dm(3) LiN(SO2C2F5)(2)/EC + DOX (5:5) electrolyte achieved above 99%. Thermal tests disclosed that this mixed electrolyte showed good thermal stability even with the existence of lithium metal. (C) 2000 The Electrochemical Society. S0013-4651 (99)08-090-8. All rights reserved.