Electrolyte for lithium secondary battery and lithium secondary battery including the same

A lithium secondary battery comprising an electrolyte, the electrolyte comprising an additive, the additive being a phosphorus compound represented by the following Formula 1:

• wherein:
• R1 to R5 are each independently selected from a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, —OR (where R is a C1-C10 alkyl group or a C6-C20 aryl group), —C(═O)Ra, —C(═O)ORa, —OCO(ORa), —(X)n—NH2 (where X is a C1-C10 alkyl group or a C1-C10 alkoxy group, and n is an integer from 0 to 10), —(X1)n—C(Ra)3 (where X1 is a C1-C10 alkyl group or a C1-C10 alkoxy group, and n is an integer from 0 to 10), —(X2)n—CH═CH2 (where X2 is a C1-C10 alkyl group or a C1-C10 alkoxy group, and n is an integer from 1 to 10), —C═N(Ra), —SRa, —S(═O)Ra, —S(═O)2Ra, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C1-C20 alkoxy group, a substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C2-C20 alkynyl group, a C2-C20 alkylene oxide group, a substituted or unsubstituted C3-C30 cycloalkyl group, a substituted or unsubstituted C6-C30 aryl group, a substituted or unsubstituted C6-C30 aryloxy group, and a substituted or unsubstituted C6-C30 heteroaryl group, where Ra is selected from a hydrogen atom, a halogen atom, a C1-C10 alkyl group, and a C6-C20 aryl group.