LITHIUM SECONDARY BATTERY

The present invention relates to a lithium secondary battery having improved high-temperature cycle characteristics, and particularly, to a lithium secondary battery including a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the positive electrode includes lithium iron phosphate and lithium nickel cobalt manganese oxide as a positive electrode active material, a loading amount of the positive electrode is in a range of 32 mg/cm2 to 60mg/cm2, and the electrolyte includes a lithium salt; a first organic solvent; a second organic solvent; a first additive; and a second additive, wherein the first organic solvent is a cyclic lactone compound, the second organic solvent is a carbonate-based organic solvent, the first additive is an oligomer including a repeating unit derived from a monomer represented by Formula 1 and a repeating unit derived from a monomer represented by Formula 2, and the second additive is an imidazole-based compound.