Rechargeable lithium battery comprising a lithium nickel cobalt manganese composite oxide cathode and an ethylene carbonate based electrolyte

Provided is a rechargeable lithium battery that includes a positive electrode including a positive active material, a negative electrode including a negative active material and an electrolyte including a lithium salt and a non-aqueous organic solvent, wherein the positive active material includes a nickel-based composite oxide represented by the following Chemical Formula 1, the non-aqueous organic solvent includes ethylene carbonate, and the ethylene carbonate is included in an amount of 7.5 to 27.5 volume% based on the total amount of the non-aqueous organic solvent. [Chemical Formula 1]LiNi x Co y Mn z O 2 (In the above Chemical Formula 1, 0.63