Dual-Confined and Hierarchical-Porous Graphene/C/SiO2 Hollow Microspheres through Spray Drying Approach for Lithium-Sulfur Batteries

Rational robust hierarchical-porous Graphene/C/SiO2 hollow microspheres (G/C/SiO2) were designed as scaffold to load sulfur. The sulfur was impregnated into the microspheres to generate sulfur-Graphene/C/ SiO2 composites (S-G/C/SiO2) for Li-S batteries. The 3D porous microspheres consist of SiO2 nanoparticles connected by interconnected graphene and carbon layer, which could leave enough room for volume changes of sulfur during the charge-discharge process, and imprison the polysulfide via physical adsorption and chemical binding, thus effectively improving the cycle stability. As a result, the S-G/C/SiO2 with 20.1 wt. % SiO2 exhibits high discharge capacities up to 1118.4 mA h g(-1) at 0.1C, an excellent rate capability of 551.7 mA h g(-1) at 5C, and an exciting cycle performance of 626.3 mA h g(-1) after 400 cycles at 0.5C (ultralow capacity decay of only 0.062% per cycle), represented to be a promising cathode material for Li-S batteries. (C) 2017 Elsevier Ltd. All rights reserved.