Non-Aqueous Electrolyte Solution Additive, Non-Aqueous Electrolyte Solution Including the Same, and Lithium Secondary Battery

The present invention relates to a non-aqueous electrolyte solution additive capable of improving lifespan characteristics of a lithium secondary battery by forming a solid-electrolyte interphase that is stable even at a high temperature and has low resistance when applied to a non-aqueous electrolyte solution, and relates to a non-aqueous electrolyte solution additive including a sultone-based compound represented by Formula I, a non-aqueous electrolyte solution including the same, and a lithium secondary battery.