SECONDARY BATTERY

The present invention provides an electrolyte solution for a lithium ion secondary battery comprising 65 to 99% by volume of a phosphate ester compound, 0.01 to 30% by volume of a fluorinated carbonate compound, and 0.1 to 10% by volume of a halogenated phosphate ester compound and/or 0.1 to 30% by volume of a solvent having a specific dielectric constant of 15 or more, and a lithium ion secondary battery having the same.