Coaxial Three-Layered Carbon/Sulfur/Polymer Nanofibers with High Sulfur Content and High Utilization for Lithium-Sulfur Batteries.

Abstract

Great progress has been made on the cyclability and material utilization in recent development of lithium-sulfur (Li-S) batteries; however, most of the sulfur electrodes reported so far have a considerable low loading of sulfur (60%), which causes a substantial decrease in energy density and is therefore difficult for application in batteries. To deal with this issue, we fabricate a novel sulfur composite with a coaxial three-layered structure, in which sulfur is deposited on carbon fibers and coated with poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS), thus enabling a high sulfur loading of 70.8 wt % without the expense of its electrochemical performance. Benefiting from the rigid conductive framework of carbon fibers and flexible buffering matrix of the polymer for blocking the diffusion loss of discharge intermediates, the as-fabricated composite electrode exhibits a high initial reversible capacity of 1272 mA h g-1 (based on the total mass of the composite), a stable cyclability with a retained capacity of 807 mA h g-1 after 200 cycles, and a high Coulombic efficiency of ∼99% upon extended cycling, offering a new selection for practical application in Li-S batteries.