Ultrastable Surface‐Dominated Pseudocapacitive Potassium Storage Enabled by Edge‐Enriched N‐Doped Porous Carbon Nanosheets

The development of ultrastable carbon materials for potassium storage poses key limitations caused by the huge volume variation and sluggish kinetics. Nitrogen‐enriched porous carbons have recently emerged as promising candidates for this application; however, rational control over nitrogen doping is needed to further suppress the long‐term capacity fading. Here we propose a strategy based on pyrolysis–etching of a pyridine‐coordinated polymer for deliberate manipulation of edge‐nitrogen doping and specific spatial distribution in amorphous high‐surface‐area carbons; the obtained material shows an edge‐nitrogen content of up to 9.34 at %, richer N distribution inside the material, and high surface area of 616 m2 g−1 under a cost‐effective low‐temperature carbonization. The optimized carbon delivers unprecedented K‐storage stability over 6000 cycles with negligible capacity decay (252 mA h g−1 after 4 months at 1 A g−1), rarely reported for potassium storage. Pyrolysis–etching of a pyridine‐coordinated polymer was used to prepare a porous carbon material with defect edge‐enriched N‐6/N‐5 doping, high surface area, and rich distribution of N defects within the material. This carbonaceous material allows full utilization of surface‐dominated capacitive K storage with ultrastable cycling.