Synergetic Effect of Nitrogen/Sulfur Dual-Doped Hierarchically Porous Carbon Networks for Li-S Batteries

The rapid specific capacity decay and poor cycle life of Li-S batteries (LSBs) can be attributed to serious shuttling of soluble lithium polysulfide between electrodes. Herein, nitrogen/sulfur dual-doped hierarchically porous carbon networks (NSC) with hierarchical pores and high N/S-doped content are constructed via a simple sol-gel route followed by two-step annealing under different atmospheres. The carbon networks are used as host materials and interlayers for LSBs to greatly improve the cycling and rate performances. The battery shows a superb incipient capacity (similar to 1000 mAh g(-1)) after 100 cycles at the current density of 0.2 C. Remarkably, it retains a superior cycling performance for 500 cycles with large specific capacities of 647.1 and 393.6 mAh g(-1) at high current densities of 2.0 and 5.0 C, respectively. Such satisfying electrochemical performances of NSC-based cells benefit from the synergetic effect of NSC materials, which not only immobilizes lithium polysulfides via strong interactions of Li-N and S-S, but also improves redox kinetics of lithium polysulfides to effectively suppress the shuttle effect. Accordingly, the reasonable design of NSC materials will be distinctly vital for promoting cycle performances of the LSBs and enhancing its practical applications.