Simple modification with amine- and hydroxyl- group rich biopolymer on ordered mesoporous carbon/sulfur composite for lithium-sulfur batteries

Abstract

Lithium-sulfur (Li-S) batteries are promising next generation batteries, and numerous porous carbons have been considered as the support materials for sulfur to address dissolution of poylsulfide. However, the weak binding energy of carbon with sulfur species causes poor cycle performance. We report that amine- and hydroxyl-rich biopolymer (chitosan) coated on ordered mesoporous carbon (OMC) can effectively capture soluble polysulfide. The strong binding of chitosan’s amine- and hydroxyl-group with the polysulfides prevents dissolution of soluble intermediates and assists dispersion of insulating final products. In addition, as chitosan is insoluble in the electrolyte, chitosan coating on the cathode sustainably increases cycle stability and coulombic efficiency of Li-S batteries. Initial coulombic efficiency of chitosan modified OMC/S composite was 81.7% and specific capacities of chitosan modified OMC/S composite were 32.4% and 51.6% higher than those of bare OMC/S composite at 100th and 140th cycle, respectively.