Nitrogen-rich microporous carbon framework as an efficient polysulfide host for lithium-sulfur batteries

Abstract

Lithium-sulfur batteries are recognized as a promising high-energy-density and low-cost energy storage devices. However, the sulfur cathode suffers from poor cycling stability resulting from the serious polysulfide shuttle. Herein, we develop a nitrogen-rich and highly porous carbon polyhedron for effectively hosting sulfur. The carbon host manifests an ultrahigh specific surface area of 3400 m2 g−1, a dominated micropore volume of 0.96 cm3 g−1, and a high-level nitrogen doping of 8.3 at.%. Such an intriguing structure could suppress the polysulfide shuttle via physical confinement by micropores and strong chemical adsorption by polar nitrogen species. Moreover, the electrically conductive carbon enables a substantially enhanced electrochemical kinetics. Consequently, the carbon/sulfur composite electrode delivers an ultralow fading rate of 0.033% per cycle at 2 C over 500 cycles and superior rate capability (483 mAh g−1 at a high 5 C rate). The present study demonstrates the potential use of nitrogen-rich porous carbon framework as an efficient polysulfide host for lithium-sulfur batteries.