Sulfur/Nitrogen Co-Doped Mesoporous Carbon for High-Performance Lithium-Ion Battery Anodes

Mesoporous carbon (MC) with assembly building blocks of different scales and heteroatom-doping is a promising material that can deliver enhanced electrochemical performance through suitable modifications in the surface-based properties of carbon electrodes. Particularly, S/N co-doped MC, with adjustable microstructure and controllable incorporation, has garnered significant interest. In this study, MCs with high specific surface areas are co-doped with S and N atoms by employing a facile aqueous self-assembly method that takes advantage of a hydrothermal doping strategy. The S/N co-doping content is adjusted by varying the amount of thiourea, and increased doping significantly enhances the specific capacitance. An electrode synthesized using 6% thiourea in phenol exhibits a discharge capacity of 657.0 mAh g−1 at 0.1 A g−1. When evaluated as electrodes of Li-ion batteries, the resultant material exhibits excellent rate capability and significant stability after 1000 cycles. This is attributed to the specific oxygen-containing functional groups, enhanced surface polarization owing to the heteroatoms, and enhanced oxygen and ion adsorption with S/N co-doping. Optimized S/N-MCs are promising candidates for application toward high-performance Li-ion battery anodes.