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 H2S gas. The MgO-impregnated and nitrogen-doped mesoporous carbon composite desulfurizers (NMC/MgO), acting as effective catalysts and large storehouses, could catalytically oxidize H2S 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–1 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.