Thermal behavior and decomposition kinetics of six electrolyte salts by thermal analysis

The thermal behavior of five lithium salts commonly used in the electrolytes of lithium-ion battery and one non-lithium salt used as a dominant salt of electrochemical capacitor was studied using simultaneous thermogravimetry (TG)–derivative thermogravimetry (DTG)–differential scanning calorimetry (DSC) under a dynamic nitrogen atmosphere. The results showed that the amount of free acid remained in the five lithium salts and their initial revolution temperature are different and the stability of all six salts falls in the order LiClO4 > LiCF3SO3 > LiTFSI > TEABF4 > LiBF4 > LiPF6. In addition, the reaction heat values associated with their decomposition processes were measured, which showed the stages for the evolution of free acid are endothermic with lower reaction heat, while for the decomposition of salts either endo- or exothermic, mainly depending on their chemical compositions. Kinetic parameters for these decomposition reaction processes were obtained by jointly using two thermal kinetic analysis methods.