Flame-Retardant and Polysulfide-Suppressed Ether-Based Electrolytes for High-Temperature Li–S Batteries
Mengxue He, Xia Li, Nathaniel Holmes, Ruying Li, Jiajun Wang, Geping Yin, Pengjian Zuo, Xueliang Sun
Abstract
Lithium–sulfur (Li–S) batteries are drawing huge attention as attractive chemical power sources. However, traditional ether-based solvents (DME/DOL) suffer from safety issues at high temperatures and serious parasitic reactions occur between the Li metal anodes and soluble lithium polysulfides (LiPSs). Herein, we propose a polysulfide-suppressed and flame-retardant electrolyte operated at high temperatures by introducing an inert diluent 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl (TTE) into the high-concentration electrolyte (HCE). Li dendrites are also efficiently suppressed by the formed LiF-rich protective layer. Furthermore, the shuttle effect is mitigated by the decreased solubility of LiPSs. At 60 °C, Li–S batteries using this nonflammable ether-based electrolyte exhibit a high capacity of 666 mAh g–1 over 100 cycles at a current rate of 0.2C, showing the greatly improved high-temperature performance compared to batteries with traditional ether-based electrolytes. The improved electrochemical performance across a range of temperatures and the enhanced safety suggest that the electrolyte has a great practical prospect for safe Li–S batteries.