Waste to Wealth: Exhausted Nitrogen-Doped Mesoporous Carbon/MgO Desulfurizers Turned to High-Sulfur-Loading Composite Cathodes for Li-S Batteries.

We demonstrate a sustainable and cost-effective route to fabricate high-sulfur-loading cathode materials with the cooperative interfaces of "sulfiphilic" and "lithiophilic" sites from the removal industry of the pollutant HS gas. The MgO-impregnated and nitrogen-doped mesoporous carbon composite desulfurizers (NMC/MgO), acting as effective catalysts and large storehouses, could catalytically oxidize HS into elemental S with high catalytic selectivity and sulfur capacity. The obtained byproduct NMC/MgO/S-CO composites possess high sulfur loading (73.8 wt %) and significant structure advantages for practical application in Li-S batteries. First, the uniform distribution of S in the NMC/MgO frameworks via the in situ catalytic oxidation approach could offer large interface area for charge transport and Li reaction. Then, the cooperative effects of the "sulfiphilic" MgO nanoparticles and the "lithiophilic" nitrogen dopants in the NMC/MgO could effectively suppress the polysulfide shuttling. Under the further assistance of physical confinement of the mesoporous NMC/MgO, the NMC/MgO/S-CO composites present excellent electrochemical performances with a high reversible capacity of 772 mAh g and a Coulombic efficiency of 93.6% at the 100th cycle at 0.2 C. These encouraging results not only develop a sustainable way to turn waste into wealth but also provide a promising strategy to product high-sulfur-loading cathode materials with uniform distribution of S through the in situ catalytic strategy for high-performance Li-S batteries.