LITHIUM SECONDARY BATTERY

The present invention relates to a lithium secondary battery including: a gel polymer electrolyte which is a polymerization reaction product of a composition containing a lithium salt, an organic solvent, an oligomer, a lithium salt-based additive, and a polymerization initiator; a positive electrode containing a lithium iron phosphate-based composite oxide; a negative electrode containing a negative electrode active material; and a separator disposed between the positive electrode and the negative electrode, wherein the oligomer is a polyvinylidene fluoride-based polymer containing a vinyl group or an acrylate group at the end thereof, the lithium salt-based additive is at least one selected from the group consisting of lithium difluoro oxalato borate, lithium tetrafluoro borate, lithium 2-trifluoromethyl-4,5-dicyanoimidazolide, and lithium difluorophosphate, and the lithium salt is different from the lithium salt-based additive.