The present invention discloses a non-
aqueous electrolyte for a secondary battery and a secondary battery thereof, the
electrolyte comprises an
electrolyte salt, a non-aqueous
solvent and an additive, the additive at least comprises: a
nitrogen-containing
heterocyclic compound as a first additive, a film-forming additive with a film-forming potential of less than 1.5 V (vs. Li + / Li) as a second additive, the specific structure of the additive is shown in the specification. The
nitrogen-containing
heterocyclic compound and the film-forming additive with the film-forming potential lower than 1.5 V (vs.Li < + > / Li) are combined for use, and the
nitrogen-containing
heterocyclic compound and the film-forming additive are regulated in a specific content ratio range to fully generate a synergistic effect, so that water catching and
acid inhibition can be effectively realized,
decomposition and gas production can be effectively inhibited at high temperature and
high voltage, the stability of the
electrolyte is greatly improved, and the service life of the electrolyte is prolonged. And an SEI film with excellent
ion transmission capability and structure /
thermal stability can be formed on the surface of the
electrode, so that the first efficiency of the battery is effectively improved, and the low-temperature performance and the cycle performance of the battery are further improved.