Template-free fabrication of high N/S co-doped carbon frameworks for stable and high-capacity potassium-ion storage

Carbon materials are considered as highly promising anode candidates for potassium-ion batteries due to their abundance, cost-effectiveness and stable structure. In this study, we use a one-step solid-state pyrolysis method for synthesizing high nitrogen and sulfur co-doped hard carbon (HNSC) using pyrene precursor with a high carbon atom ratio. The prepared HNSC possesses self-template pore channels with high sulfur and nitrogen co doping, exposing abundant edge active sites that enhance potassium storage capacity. Therefore, the optimized HNSC anode displays a high reversible capacity of 364.6 mAh g −1 after 100 cycles at 100 mA g −1 , excellent rate capability of 134 mAh g −1 at 5000 mA g −1 and cycling life with specific capacity of 171 mAh g −1 over 700 cycles at 2000 mA g −1 . Additionally, the potassium ion hybrid capacitor constructed using HNSC and activated carbon exhibited stable electrochemical performance, demonstrating its potential for application. The study presents a straightforward and versatile approach for fabricating anode materials of in new secondary batteries.