A comprehensive investigation on both the combustion characteristic and electrochemical performance of lithium battery with flame retardant tris (2-chloropropyl) phosphate

Thermal failures of lithium batteries have become more and more critical for the further development of energy storage technologies. Adding flame retardant additives has been proven promising to improve safety. However, the electrochemical performance usually degrades with additives. It is important to balance flame retardancy and electrochemical performance. In this study, both the combustion characteristics and electrochemical performance of Tris (2-ChloroPropyl) Phosphate (TCPP) are investigated to seek its potential for application in practical batteries. A novel experimental setup as well as key parameters are proposed to quantificationally characterize the flame retardancy of TCPP. The experimental results indicate that only 5 wt% of TCPP additives can lengthen both the jet delay times and auto-ignition delay times of the electrolyte jets by 50.6 % and 38.1 %, indicating the excellent flame-retardant efficiency of TCPP. The lithium salt in the electrolytes also presents significant flame retardancy on the combustion of electrolyte jets, particularly lengthening the auto-ignition delay times by as high as 74.8 %. Tests on the electrochemical performance reveal that 5 wt% of TCPP additives have negligible impacts on the discharge capacity. The overall deterioration of the discharge retention ratio is less than 6.0 % during long-term and various C-rates cycling tests.