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

A lithium secondary battery comprising:

• a cathode comprising a cathode active material,
• an anode comprising an anode active material, and
• a non-aqueous liquid electrolyte comprising:
• a lithium salt;
• a non-aqueous organic solvent;
• a piperazine derivative additive represented by Formula 1 having an oxidation potential lower than an oxidation potential of the non-aqueous organic solvent by about 2 V to about 4 V:
• wherein, in Formula 1,
• at least one of X and Y is selected from a C1-C60 alkyl group, a C1-C60 aminoalkyl group, a C1-C60 thioalkyl group, a C1-C60 hydroxyalkyl group, a C1-C60 alkylnitrile group, and a substituted or unsubstituted C6-C60 aryl group, and the unselected rest of X and Y is a hydrogen atom;
• R1 to R4 are each independently selected from a hydrogen atom, a deuterium atom, a halogen atom, a hydroxyl group, a cyano group, a nitro group, an azido group, an amino group, an amido group, an amidino group, a hydrazine group, a hydrazone group, a carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a thiol group, —C(═O)—H, a substituted or unsubstituted C1-C60 alkyl group, a substituted or unsubstituted C1-C60 alkoxy group, a substituted or unsubstituted C1-C60 heteroalkyl group, a substituted or unsubstituted C2-C60 alkenyl group, a substituted or unsubstituted C2-C60 alkynyl group, a substituted or unsubstituted C3-C10 cycloalkyl group, a substituted or unsubstituted C3-C10 heterocycloalkyl group, a substituted or unsubstituted C2-C10 cycloalkenyl group, a substituted or unsubstituted C2-C10 heterocycloalkenyl group, a substituted or unsubstituted C6-C60 aryl group, a substituted or unsubstituted C6-C60 aryloxy group, a substituted or unsubstituted C2-C60 heteroaryl group, -(Q1)r-(Q2)s, —N(Q3)(Q4)(Q5), —P(═O)(Q6)(Q7), and —P(Q8)(Q9)(Q10)(Q11);
• wherein at least one of R11 to R14 and at least one of R21 to R30 are optionally linked to each other to form a substituted or unsubstituted, saturated or unsaturated ring;
• Q1 is at least one selected from —O—, —S—, —C(═O)—, a substituted or unsubstituted C1-C60 alkylene group, a substituted or unsubstituted C2-C60 alkenylene group, a substituted or unsubstituted C3-C10 cycloalkylene group, a substituted or unsubstituted C3-C10 heterocycloalkylene group, a substituted or unsubstituted C2-C10 cycloalkenylene group, a substituted or unsubstituted C2-C10 heterocycloalkenylene group, a substituted or unsubstituted C6-C60 arylene group, and a substituted or unsubstituted C2-C60 heteroarylene group;
• Q2 to Q11 are each independently selected from a deuterium atom, a halogen atom, a hydroxyl group, a cyano group, a nitro group, an azido group, an amino group, an amido group, an amidino group, a hydrazine group, a hydrazone group, a carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a thiol group, a substituted or unsubstituted C1-C60 alkyl group, a substituted or unsubstituted C1-C60 alkoxy group, a substituted or unsubstituted C1-C60 heteroalkyl group, a substituted or unsubstituted C2-C60 alkenyl group, a substituted or unsubstituted C2-C60 alkynyl group, a substituted or unsubstituted C1-C60 alkoxy group, a substituted or unsubstituted C3-C10 cycloalkyl group, a substituted or unsubstituted C3-C10 heterocycloalkyl group, a substituted or unsubstituted C2-C10 cycloalkenyl group, a substituted or unsubstituted C2-C10 heterocycloalkenyl group, a substituted or unsubstituted C6-C60 aryl group, a substituted or unsubstituted C6-C60 aryloxy group, and a substituted or unsubstituted C2-C60 heteroaryl group;
• and
• r and s are each independently an integer from 1 to 5, wherein,
• when r is 2 or greater, groups Q1 are each identical to or different from each other, and
• when s is 2 or greater, groups Q2 are each identical to or different from each other,
• wherein the lithium secondary battery further comprises a film disposed between the cathode and the electrolyte, wherein the film comprises at least a part of the additive.