NONAQUEOUS ELECTROLYTE AND LITHIUM SECONDARY BATTERY COMPRISING SAME

摘要

The present invention provides a nonaqueous electrolyte and a lithium secondary battery comprising same, the nonaqueous electrolyte comprising: i) a first lithium salt; ii) lithium bis(fluorosulfonyl)imide, which is a second lithium salt; iii) a phosphazene-based compound, which is a first additive; and iv) a nonaqueous organic solvent. The lithium secondary battery comprising the nonaqueous electrolyte according to the present invention not only has improved output properties but also can have improved output and capacity properties after high-temperature storage by forming a strong SEI film on the surface of a negative electrode at the time of initial charging and preventing the decomposition of the surface of a positive electrode and the oxidation reaction of the electrolyte by providing flame retardancy in a high-temperature environment.