Promoting the synergistic effect of sulfur immobilization and polysulfides trapping by nitrogen functionalized interconnected hollow carbon nanocages for high-performance lithium–sulfur batteries

Abstract

Although lithium sulfur battery is considered as one of the promising energy storage systems beyond lithium ion battery, the severe polysulfides dissolution and sluggish reaction kinetics with low level sulfur loading still retard the practical application of lithium sulfur battery. Herein, an interconnected hollow carbon nanocages with tailored nitrogen-doping (CNCs) is reported via confined pyrolysis of Zn, Co zeolitic imidazolate framework within the resorcinol-melamine-formaldehyde shell. The interconnected cavity and the porous carbon skeletons guarantee the well-dispersion and immobilization of sulfur cathode even with high sulfur content of 80 wt %. In addition, developed microporosity and numerous nitrogen functional groups on the carbon surface favor for the chemisorption, conversion of polysulfide and uniform growth of Li2S. Hence, the resulting S/CNC-1 cathode delivers a high initial capacity of 1310 mAh g−1@0.2 C, excellent rate performance with 762 mAh g−1 at 8 C and ultra-long lifespan with a reversible capacity of 841 mAh g−1 after 800 cycles. More importantly, a high capacity of 4.8 mAh cm−2 is attained at high sulfur content of 80 wt% and areal sulfur loading of 4.2 mg cm−2. These findings provide an effective method for future development of practical lithium sulfur battery with superior rate performance and long lifespan.