Flame-Retardant Electrolyte Solution for Dual-Ion Batteries

The flammability of organic electrolyte solutions has a safety risk during the large-scale application of energy storage devices. Therefore, it is essential to suppress the flammability of organic electrolyte solutions. In this article, the flame-retardant electrolyte solution of 3 M LiPF6-ethyl methyl carbonate (EMC)/trimethyl phosphate (TMP) (7:3 by vol) has been applied in a Li/graphite dual-ion battery. Both the initial-cycle discharge capacity (almost 100 mAh g–1) and capacity retention rate (92.3% after 450 cycles) surpass those for the battery using 1 M LiPF6-EMC. Besides, the burning times of the above electrolyte solutions are 6 and 66 s, respectively. Conventional electrochemical tests, ex situ X-ray diffraction, and nuclear magnetic resonance have been carried out to explore the influences of TMP on PF6– in EMC/TMP mixed solvents.