Preparation of reduced carbon-wrapped carbon-sulfur composite as cathode material of lithium-sulfur batteries

Sulfur is a promising cathode material for lithium-sulfur batteries as it possesses high theoretical specific capacity and low cost. In this work, the dispersion for sulfur and restriction for lithium polysulfides have been combined to improve the performance of lithium-sulfur batteries. Sulfur is dispersed on acetylene black particles at first and then reduced carbon coating wraps acetylene black-sulfur particles. The reduced carbon coating is fabricated by deoxidizing carbon precursor which is the product of reaction between sucrose and concentrated sulfuric acid. Morphology, structure and electrochemical properties of materials have been characterized and tested. Results show that sulfur envelops acetylene black particles and is uniformly dispersed in acetylene black-sulfur composite. A layer of deoxidized carbon coating wraps acetylene black-sulfur particles. The carbon-sulfur composite with deoxidized carbon electrode exhibits higher specific capacity and cycle stability in comparison with acetylene black-sulfur composite electrode. Besides, the carbon-sulfur composite with deoxidized carbon electrode displays high coulombic efficiency, which is attributed to the restriction for dissolution of lithium polysulfides through the deoxidized carbon coating.