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

An electrolyte for a sodium secondary battery comprising:

• a sodium molten salt, a first additive represented by Chemical Formula 1, and a second additive represented by Chemical Formula 2, wherein each of the first additive and the second additive has an amount of 0.1 to 30 wt % relative to the total weight of the electrolyte for the sodium secondary battery:
• NaxA [Chemical Formula 1]
• NaD [Chemical Formula 2]
• in Chemical Formulas 1 and 2,
• A is a sulfur oxide ion, or a nitrate ion,
• x is an integer selected from 1 to 4 depending on an ionic valency of A;
• and
• D is selected from NCO—, NCS- or compounds represented by Chemical Formulas 3 to 6,
• in Chemical Formulas 3 to 6,
• R1 to R6 are each independently hydrogen, (C1-C10)alkyl, (C1-C10)alkoxy, (C2-C10)alkenyl, (C2-C10)alkynyl, (C6-C12)aryl, (C3-C12)heteroaryl or (C6-C12)aryl(C1-C10)alkyl;
• R5 and R6 may be linked to each other to form an alicyclic ring or an aromatic ring;
• Z1 and Z2 are each independently —CO— or SO2—, and
• the alkyl, alkoxy, alkenyl, alkynyl, aryl, heteroaryl and arylalkyl of R1 to R6 and the alicyclic ring and the aromatic ring of R5 and R6 may be further substituted with halogen, amino, nitro or (C1-C10)alkyl.