A robust electrospun separator modified with in situ grown metal-organic frameworks for lithium-sulfur batteries

Abstract Because of the existence of the soluble lithium polysulfides, the requirement for an ideal separator for lithium sulfur (Li-S) batteries is higher than that in LIBs. Herein, we report a double-layered MOF-PAN/rGO-PAN nanofiber membrane as an alternative to commercial polyolefin separators for Li-S battery. This PAN-based membrane possesses the intrinsic advantages of good mechanical property, thermal stability and high electrolyte uptake, showing a high lithium ion transference number of 0.81. The in situ grown MOF particles by low pressure chemical vapor deposition attach on the surface of the nanofibers tightly, and these exposed particles can maximize the utilization for trapping polysulfides through chemisorption. With this novel functional separator, the Li-S batteries can provide a high initial capacity of 1302 mAh g−1 at 0.5 C. At a high rate of 5 C, the capacity decay rate is only 0.03% per cycle over 600 cycles. More importantly, even with a high sulfur loading of 7.7 mg cm−2, the Li-S battery is able to deliver a high areal capacity of 7.8 mAh cm−2 after 50 cycles.