LITHIUM SECONDARY BATTERY

A lithium secondary battery comprising a positive electrode, a negative electrode, a separator inserted between the positive electrode and the negative electrode and a non-aqueous electrolyte is provided. The positive electrode comprises a first positive electrode active material represented by following Chemical Formula 1. And the non-aqueous electrolyte comprises a first lithium salt, a second lithium salt represented by following Chemical Formula 2 and a non-aqueous organic solvent. [Chemical Formula 1]Li x M y O z [Chemical Formula 2]Li + RCOO - (In Chemical Formulae 1 and 2, M=Ni a Mn b CO c , in which 0