An intrinsic safe siloxane ether-based electrolyte for lithium-sulfur batteries at high temperatures

As the next candidate of secondary batteries, lithium-sulfur (Li-S) batteries are hampered by short cycle life and safety issues caused by combustion of electrolytes and unstable cycling performance generated by Li dendrites growth, which become more serious when Li-S batteries are operated at high temperatures. To solve these problems, an intrinsic flame-retardant siloxane ether-based electrolyte, 2.5 M LiFSI/tetrapropoxysilane (TPOS), is innovatively investigated in Li-S batteries with sulfurized pyrolyzed poly(acrylonitrile) (SPAN) cathode at 80 degrees C. This electrolyte exhibits desirable flame retardancy, unique solvation structure and excellent interfacial stability. Particularly, this electrolyte performs outstandingly in cathode protection derived from the robust and flexible electrolyte/electrode interphases simultaneously for Li metal anode and SPAN cathode. Li-S batteries delivered a reversible capacity of 760 mAh g(SPAN)(-1) (1535 mAh g(sulfur)(-1)) and a capacity retention of 98.4 % after 85 cycles at 1C and 80 degrees C. This work provides the concept and paves the way to develop high temperature Li-S batteries.