Abstract: Succinonitrile（SN） was added to the electrolyte solution containing 1 mol/L LiPF6 in ethylene carbonate （EC）， dimethyl carbonate（DMC），and methyl ethyl carbonate（EMC） （volume ratio of 1∶1∶1）.The effects of SN on electrochemical windows，specific capacity，charge-discharge efficiency for the first cycle，and cycling performance of lithium ion battery were researched by cyclic voltammetry（CV），charge-discharge cycle performance，and electrochemical impedance spectra（EIS）．The results indicated that the application of high purity SN improved the specific capacity，initial charge-discharge efficiency，electrochemical windows，thermal stability，and cycling performance of the electrolyte solution.

Key words: succinonitrile, electrolyte, additive, Li-ion battery