Rods-like Sulfur Immobilized on Reduced Graphene Microspheres for Lithium–Sulfur Batteries

Abstract

We demonstrate 2D rod-like nanosulfur (nS)deposited onto microspherical reduced graphene oxide architectures for improved performance of lithium–sulfur (Li–S) batteries. The combined chemistry of a spray-frozen assembly and ozonation drives the formation of a radially oriented open-porous structure and an overall microspherical morphology as well as uniform distribution and high loading of rod-like nS. Moreover, an optimum composition and strong bonding of the rGO/nS hybrid enables the optimization of redox kinetics for high sulfur utilization and high-rate capacities. The resulting rGO/nS hybrid provides a specific capacity and first-cycle Coulombic efficiency of 1269.1 mAh g–1 and 98.5%, respectively, which are much greater than those of ice-templated and physically mixed rGO/nS hybrids and radially oriented open-porous rGO/bulk sulfur with the same hybrid composition. A 4C capacity of 510.3 mAhg–1 and capacity decay of 0.08% per cycle over 500 cycles (70.9% of the initial capacity over 300 cycles) also support the synergistic effect of the rod-like nS strongly interacting with the radially oriented open-porous rGO microspheres. Figure 1