Electrolyte for electrochemical device and the electrochemical device thereof

The present invention provides an electrolyte for electrochemical device and the electrochemical device thereof. The electrolyte comprises 9.95ˆ¼19.95wt% of a salt; 80.0ˆ¼90.0wt% of a non-aqueous solvent; 0.05ˆ¼10.00wt% of an additive comprising a compound represented by below formula (I) or (II): wherein X 1 , R 1 , and R 4 ˆ¼R 10 is defined as herein. Besides, the present invention also provides a method for enhancing cycle life of electrochemical device which accomplished by adding said additive to an electrolyte of electrochemical device.