Advanced low-flammable pyrrole ionic liquid electrolytes for high safety lithium-ion batteries

With the rapid development of new energy vehicles, the safety of lithium-ion batteries (LIBs) is of increasing concern. Currently, the widely used carbonate-based organic electrolytes have a low ignition point, so it is important to develop high-safety LIBs electrolytes. In this work, a new electrolyte system was configured using commercial carbonate-based organic solvents mixed with [BMP]TFSI pyrrole-type ionic liquids in different proportions. It was experimentally verified that the newly configured electrolyte system led to a significant reduction in the flammability of the battery and even improved the electrochemical performance of the battery, while ensuring the proper function of the electrolyte. As the [BMP]TFSI content increases, the electrolyte self-extinguishing time decreases and the thermal stability increases. In particular, electrolytes with 30 wt% [BMP]TFSI addition exhibit the best balance of flame retardancy and electrochemical performance. The electrolyte system at this addition level has a high thermal stability and a significantly higher oxidation potential, which facilitates stable Li+ embedding and detaching and improves the stability of the SEI film. The assembled cells show a capacity retention of 99.58 % and a coulombic efficiency close to 100 % even after 200 cycles. The excellent cycle performance and high safety indicate that [BMP]TFSI has great prospects for application in the LIBs market. This is a guideline for the development of high-safety and high-capacity LIBs.