Evaluation of composite flame-retardant electrolyte additives improvement on the safety performance of lithium-ion batteries

Safety requirements for lithium-ion batteries (LIBs) have become increasingly stringent with the rapid development of LIBs. We synthesize composite flame-retardant electrolyte additives (pentafluoroethoxy cyclotriphosphazene and dimethylacetamide) for LIBs to improve the safety performance of LIBs during use. The study tests the electrochemical performance of LIBs whose electrolytes contain the aforementioned additives using an electrochemical workstation and a LIB parameter tester. An experiment on self-extinguishing time is conducted to test the flame retardancy and ionic conductivity of the prepared composite flame-retardant electrolytes. Differential scanning calorimetry (DSC) and thermogravimetry are conducted to test the cathode materials of the LIBs after cycling at different heating rates. Various nonisothermal thermodynamic models are used to analyze the experimental DSC data, and the cathode materials’ apparent activation energy and thermodynamic parameters are obtained. Finally, multivariate linear fitting is conducted to simulate the thermal decomposition reaction of the cathode materials.