Edge-nitrogen enriched carbon nanosheets for potassium-ion battery anodes with an ultrastable cycling stability

Edge-nitrogen (pyridinic/pyrrolic nitrogen) doped carbon materials have been considered as promising anodes for potassium ion batteries (KIBs), which can provide a high surface-induced capacitive capacity beyond the K+-intercalated mechanism. However, achieving a high-level edge-nitrogen doping is still a great challenge owning to inevitable introduction of graphitic nitrogen into carbon materials via conventional pyrolysis process. Herein, we design porous carbon nanosheets with bundant defects and edge sites to graft nitrogen atoms to achieve a high-level edge-nitrogen doping (88.36%). The optimized edge nitrogen doped carbon nanosheets (ENCNs-60 0) exhibits a high reversible capacity of 443 mAh g(-1) at 0.1 A g(-1) after 200 cycles, excellent rate performance (175 mAh g(-1) at 20 A g(-1)), and ultrastable cycling stability (246 mAh g(-1) at 5 A g(-1) over 10,000 cycles). Density functional theory calculations and kinetic studies confirm that both edge-nitrogen doping and explanded interlayer distance are greatly conducive for the adsorption and diffusion of K+ , thereby ensuring enhanced potassium-storage performance with a synergistic adsorption-intercalation mechanism. (C) 2021 Elsevier Ltd. All rights reserved.