HNO3 pre-oxidation-tuned microstructures of porous carbon derived from high-sulfur coal for enhancing capture and catalytic conversion of polysulfides

Heteroatoms-doped carbon materials have received increasing interest as promising sulfur hosts for lithium-sulfur (Li-S) batteries. Herein, high-sulfur coal was selected as the low cost and earth-abundant precursor and HNO3 pre-oxidation was adopted to tune the microstructure of N,O,S-multidoped three-dimensional porous carbon (NOSTPC) to facilitate affinity and conversion toward polysulfides. HNO3 pretreatment significantly increases the specific surface area, pore volume, and the content of pyrrolic nitrogen and the defects in NOSTPCs. HNO3 pre-oxidation increases the specific capacity of Li-S battery with NOSTPC as the sulfur host from 559.3 to 860.4 mAh g−1 at 1C, and the capacity retention from 67% to 81% after 200 cycles. The satisfying performance benefits from that oxidation pretreatment improves the chemical adsorption of polysulfides by NOSTPC(O), and accelerates the kinetic conversion of polysulfides together with the catalytic oxidation of Li2S. Accordingly, the good performance of high-sulfur coal-based NOSTPCs can not only promote practical application of Li-S batteries, but also facilitate the efficient utilization of high-sulfur coal.