Disclosed are a non-aqueous electrolyte comprising a lithium salt and a solvent, the electrolyte containing, based on the weight of the electrolyte, 10-40 wt % of a compound of Formula 1 or its decomposition product, and 1-40 wt % of an aliphatic nitrile compound, as well as an electrochemical device comprising the non-aqueous electrolyte. Also disclosed is an electrochemical device comprising: a cathode having a complex formed between the surface of a cathode active material and an aliphatic nitrile compound; and an anode having formed thereon a coating layer containing a decomposition product of the compound of Formula 1. Moreover, disclosed is an electrochemical device comprising: a cathode having a complex formed between the surface of a cathode active material and an aliphatic nitrile compound; and a non-aqueous electrolyte containing the compound of Formula 1 or its decomposition product. In addition, disclosed is an electrochemical device comprising: an anode having formed thereon a coating layer containing a decomposition product of the compound of Formula 1; and a non-aqueous electrolyte containing the compound of Formula 1 or its decomposition product.