NON-AQUEOUS ELECTROLYTE FOR SECONDARY BATTERY AND SECONDARY BATTERY HAVING THE SAME

A non-aqueous electrolyte for secondary battery and a lithium ion secondary battery capable of lowering viscosity of an electrolyte while maintaining a low concentration of a free solvent of the electrolyte are provided. The non-aqueous electrolyte for a the secondary battery includes an electrolytic salt having an electrolytic salt concentration of about 0.5 M (mol/L) to about 3.8 M (mol/L), a first solvent having a solubility of the electrolytic salt ranging from about 100 g to about 400 g dissolved in 100 g of the first solvent, and a second solvent has a solubility of the electrolytic salt of less than or equal to about 1 g dissolved in 100 g of the second solvent, wherein the first solvent includes a coordination solvent coordinated with an ionized ion from the electrolyte salt and a free solvent that is not coordinated with an ionized ion from the electrolyte salt, and a peak area ratio of the free solvent determined by a Raman spectrum is less than about 20 %.