Chitosan Modified with Reduced Graphene Oxide Binder for Lithium-Sulfur Battery

Abstract

The lithium-sulfur battery is a great promising candidate for next generation high energy density batteries. However, the poor conductivity of sulfur and the dissolution of soluble molecular intermediates (lithium polysulfide) interrupt practical application. To address this issue, the chitosan modified with reduced graphene oxide (Chitosan/rGO) was prepared as a binder in order to improve the electrical conductivity of sulfur and suppress the dissolution of lithium polysulfide into the electrolyte. The positively charged amino group in chitosan readily binds with negatively charged surface of rGO. The high conductivity of rGO provided facile pathway for electron and ion transport and the polar functional groups in chitosan could trap the lithium polysulfide due to their high affinity which was carefully confirmed by cyclic voltammetry. The chitosan/rGO binder with optimized composition showed enhanced initial discharge capacity, 1342 mAh g-1 at 0.05 C and the reversible specific capacity after 100 cycles was 856 mAh g-1 at 0.2 C. These are attributed to synergistic effect between chitosan and rGO. This work offers a simple and effective ways for improving the capacitive performance of Li-S batteries for practical applications.