Low‐Temperature Carbonization Synthesis of Sulfonic Group Dominated N/S Co‐Doped Carbon for High‐Performance Potassium‐Ion Batteries

Abstract The nitrogen/sulfur (N/S) co‐doping strategy has gained significant attention in the development of carbon‐based anodes for potassium‐ion batteries (PIBs) due to its capapcity to enhance specific capacity and accelerate reaction kinetics. Yet, the C─S bond‐driven conversion reaction would inevitably induce critical challenges, including poor stability and high charging voltage, thereby severely impeding the commercialization of N/S co‐doped carbon anodes. Herein, a novel sulfonic group dominated N/S co‐doped carbon (NSAC‐600) is synthesized via a facile low‐temperature carbonization strategy with coal tar pitch as a precursor. The sulfonic groups in NSAC‐600 have strong sulfur‐locking ability, that can suppress the formation of potassium polysulfides during K storage. Moreover, the N and sulfonic groups synergistically create abundant active sites for K + adsorption, expand the carbon interlayer spacing, and help to create rapid charge diffusion pathways. Thereby, the NSAC‐600 can deliver high‐rate performance (217.0 mAh g −1 at 5 A g −1 ), good cycling stability (without any capacity decay after 1400 cycles at 2 A g −1 and stable operation for 5600 cycles at a high current density of 5 A g −1 ) and low depotassium voltage. An “adsorption/intercalation/limited‐conversion” mechanism is proposed to elucidate the potassium storage behavior in this novel carbon material. This work may provide a new horizon for advanced N/S co‐doped carbon anodes.