The present invention provides: a fluorinated solvent having a specific structure; a non-aqueous electrolyte for a secondary battery, including a lithium salt and the fluorinated solvent; and a secondary battery including the non-aqueous electrolyte. A sulfone-group-containing fluorinated ether or ester compound having a specific structure, according to the present invention, has low viscosity and excellent flame retardancy without deficient solubility of a lithium salt. Therefore, the sulfone-group-containing fluorinated ether or ester compound according to the present invention can be advantageously used as a solvent of a non-aqueous electrolyte for a secondary battery and, specifically can realize excellent battery characteristics and flame retardancy.
