Abstract: The application of cyclohexyl benzene（CHB）as the overcharge protection additive in lithium ion batteries was analyzedThrough 1C overcharge testing,battery performance testing, electrochemical impedance testing，electrolyte conductivity and self-discharge testing,the use of cyclohexyl benzene as the overcharge protection additive and the effect of cyclohexyl benzene on battery performance were investigatedThe possible mechanism of cyclohexyl benzene as the overcharge protection addtive was discussed.When the content of cyclohexyl benzene was more than 5%(mass),the battery could be protected from explosion.When the content of the cyclohexyl benzene exceeded 7%(mass),a detrimental effect on battery performance was foundCyclohexyl benzene could also decrease electrolyte conductivity,leading to increased self-dischargeThe proper content of cyclohexyl benzene was between 5%(mass) and 7%(mass).