A wheat flour derived hierarchical porous carbon/graphitic carbon nitride composite for high-performance lithium–sulfur batteries

Abstract

To buffer the volume variation of sulfur and suppress the shuttle effect of long-chain lithium polysulfides during the cycling of Li-S batteries, it is essential to simultaneously design suitable pore structures and tune the surface chemistry of carbon-based sulfur hosts. However, the associated low yield and high cost of such delicately constructed carbon materials have been the major bottleneck for their practical utilization. Herein, we present a hundred-gram fabrication of a graphitic carbon nitride@hierarchical porous carbon (g-C3N4@HPC) composite, which is derived from low-cost biomass and used as the sulfur host for Li-S batteries. On this material, interconnected and hierarchical porosity of HPC physically traps the polysulfides and buffers the volume variation, and in the meantime, the uniformly dispersed g-C3N4 nanoparticles and N dopants on it provide strong chemical affinity to further immobilize the polysulfides. Therefore, the g-C3N4@HPC/S cathode delivers a high initial capacity of 1150.1 mAh g−1 and excellent cycling stability with a very small capacity decay of 0.024% cycle−1 for 250 cycles, at a high sulfur loading of 64.5 wt%. Importantly, this g-C3N4@HPC composite is derived from very cheap and eco-friendly precursors, enabling the hundred-gram production at bench-top scale, which shows significant viability for practical Li-S battery application.