posted on 2021-08-09, 16:04authored byMengxue He, Xia Li, Nathaniel Graham Holmes, Ruying Li, Jiajun Wang, Geping Yin, Pengjian Zuo, Xueliang Sun
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.