In this study, lithium-sulfur (Li-S) cells using mixed imidazolium salts and lithium salts for the electrolytes are investigated as a means to improve discharge performance and cycle-life characteristics. By introducing 5 or 10 vol.% of imidazolium salt into the electrolytes containing lithium salts, the Li-S cells give a greatly enhanced discharge capacity of > 600 mAh g-1 up to the 100th charge-discharge cycle. Furthermore, both the discharge capacity and the average discharge voltage at a high discharge rate, as well as the low-temperature performance, are all dramatically improved when compared with those of conventional cells using organic electrolyte solvents and lithium salts. (c) 2005 Elsevier B.V. All rights reserved.