Gel polymer electrolyte with ionic liquid for high performance lithium sulfur battery

Poly(vinylidenefluoride-hexafluoropropylene)[P(VDF-HFP)] membrane with porous structure was prepared by a simple phase separation process. The gel polymer electrolyte (GPE) prepared by combining the porous membrane with N-methyl-N-butylpyrrolidinium bis(trifluoromethanesulfonyl)imide ionic liquid shows good thermal stability, high anodic oxidation potential (> 5.0 V vs. Li/Li+) and good interfacial stability with lithium electrode. The lithium sulfur battery with the GPE delivers an initial discharge capacity 1217.7 mAh g− 1 and maintains a reversible capacity of 818 mAh g− 1 after 20 cycles at a current density of 50 mA g− 1.