The Study Of Solid Electrolyte Interface In Lithium Ion Batteries

Solid Electrolyte interface (SEI) was formed during the first cycle inLithium ion batteries. SEI played a important role in preventing the sidereactions between solvents and active material, and SEI also could restrainthe intercalation of solvent. So the quality of SEI film was one of the mostimportant factors for the cycle performance, discharge performance andsafety in lithium ion batteries.In order to study the formation mechanism of SEI film, factorsaffecting SEI film, and improvement of SEI film, the paper employedprismatic lithium-ion battery to determine the quality of SEI film based onDOE experiments of formation conditions. And electrochemicalperformance, including cyclic performance, impedance and polarizationpotential and other electrochemical properties were determined by CC-CVcharging and discharging, electrochemical impedance spectroscopytechniques, and so on. The composition and thermal stability of SEI filmwere analyzed by FTIR and DSC.To obtain different properties of SEI film, the paper designed DOEwith temperature, formation current and state of charge during theformation process. And we assessed the different properties of SEI film byusing a variety of techniques to establish a useful comprehensiveassessment method. The results show that, the formation conditions with0.05C current, charging to30%SOC at30℃, formed the best overallperformance of SEI film.