Diphenyl guanidine vulcanization accelerators enable sulfurized polyacrylonitrile cathode for high capacity and ether-compatible by fast kinetic

Abstract

Sulfurized polyacrylonitrile (SPAN) cathode shows excellent electrochemical performance in carbonate electrolyte for lithium-sulfur batteries. However, the limited redox conversion rate of SPAN cathode in ether electrolyte would lead to high solubility of the intermediate polysulfide Li2Sn(n ≤ 4) and shuttling, resulting in a low performance of corresponding lithium-sulfur battery, even though ether-based electrolytes are more suitable in terms of Li metal anode. In addition, SPAN is comparatively lower sulfur loading (<50 wt%) reduced its value. Improving the sulfur loading and accelerate the redox conversion of SPAN to be compatible with ether electrolyte will be one of the most promising cathode of lithium-sulfur batteries. Here, we introduced a sulfurized polyacrylonitrile cathode (SPAN-DG) with high sulfur loading (52 wt%) and high conductivity prepared by diphenylguanidine as vulcanization accelerator into lithium-sulfur battery based on ether electrolyte. This study found that SPAN-DG cathode with high conductivity can fast reaction kinetics and successfully inhibit the dissolution of lithium polysulfide and shuttle in ether electrolytes, shows good electrochemical performance. SPAN-DG cathode deliver a specific capacity of 879 mAh g−1 and 661 mAh g−1 (based on the mass of cathode) at rates of 0.1C and 1C (1C = 700 mA g−1), respectively.