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.