Due to the wide electrochemical window and high ionic conductivity, the 1-methyl-3-ethylimidazolium chloride (MeEtImCl) room temperature molten salt (RTMS) was investigated as the medium for lithium battery in the present work. The addition of C6H5SO2Cl to the RTMS was shown to improve its chemical stability and the reversibility of the lithium electrode because of the removal of AI(2)Cl(7)(-) from the melt. Electrochemical reaction which occurred at the LiCoO2 was studied and the carbon current collector was found to interact with the melt. Out of the various carbon materials studied, graphite was found to be the best material. A LiAl/LiCoO2 battery using RTMS as the electrolyte was assembled for battery test. Satisfactory results were obtained in preliminary cycling, showing a cell voltage of 3.45 V with better than 90% coulombic efficiency and a discharging capacity of 112 mA h/g LiCoO2 at current density of 1 mA/cm(2).