Exploration of microporous bio-carbon scaffold for efficient utilization of sulfur in lithium-sulfur system

Coir pith, a sustainable and renewable bio-waste material was activated and the porous carbon thus obtained has been explored for the first time as a scaffold for sulfur cathode. Unlike the reported bio-scaffolds, this study demonstrates the possibility of accommodating about 70 wt.% sulfur within the pores of bio-carbon, without leaving any bulk sulfur on the carbon surface. The naturally available lignin and cellulose content of coir pith offers advantages of porogen triggered pore volume of 0.86 cm3/g and the Coir pith derived carbon (CPC) is bestowed with an appreciable surface area of 1952 m2/g. CPC provides improved electrical conductivity and better confinement of sulfur against dissolution of polysulfides and the required space to admit volume exhalation of the active material, especially when 50 wt.% sulfur is loaded to form CPC/S-50 composite. As a result, CPC/S-50 cathode tolerates 1C rate condition and exhibits a progressive capacity of 695 mAh/g with 95% Coulombic efficiency. The study recommends CPC as yet another potential bio-scaffold for the effective utilisation of sulfur in Li-S system.