Facile preparation of nitrogen-doped hierarchical porous carbon as a sulfur cathode host for high performance lithium-sulfur batteries

Lithium-sulfur battery is a promising energy storage system due to its high theoretical energy density and low cost. Unfortunately, it still suffers from poor cycling life and low coulombic efficiency caused by the shuttling effect of lithium polysulfides. Herein, we designed a nitrogen-doped hierarchical porous carbon host (NHPC) for physical and chemical confinement of polysulfides to effectively reduce the shuttling effect. This NHPC was prepared by a simple one-step pyrolysis process using low-cost ascorbic acid as the carbon source, melamine as the nitrogen source and Zn(NO3)2 as the pore generating and carbon exfoliation agent. The resulted NHPC was found to possess randomly stacked ultrathin holy carbon sheets, high BET surface area and pore volume, rich micro- and meso-pores and enriched nitrogen doping. When infiltrated with sulfur, the resulted NHPC/S material was found to exhibit excellent electrochemical cycling performance. It delivered a high initial capacity of 1200 mAh/g at 0.2C, a reversible capacity of 729 mAh/g after 300 cycles at 1.0C and excellent cycling stability with a capacity decay of only 0.057% per cycle after 300 cycles at 1.0C. This work demonstrated a facile and efficient route to synthesize nitrogen-doped hierarchical porous carbon host for immobilization of sulfur in Li–S battery technology.