Highly Nitrogen‐Doped Porous Carbon Nanosheets as High‐Performance Anode for Potassium‐Ion Batteries

Potassium‐ion batteries (PIBs) represent a promising alternative to lithium‐ion batteries owing to the high abundance and low cost of potassium resources. However, it is still a challenge to design anode materials with superior electrochemical performance because of the intrinsic large ionic radius and heavy molar mass of K + . Here, highly nitrogen‐doped porous carbon nanosheets (N‐PCNs) were fabricated through a template‐removal method. As an anode in PIBs, N‐PCNs exhibits superior rate property of 127.5 mAh g −1 at a current density of 5 A g −1 and cycling stability of 151.2 mAh g −1 after 10000 cycles at 1 A g −1 . These remarkable performances originate from ultra‐high N doping (12 at%) as well as high specific surface area (848.3 m 2  g −1 ) with abundant hierarchical pores, which supply numerous active sites for K + insertion/extraction, enhance the electronic conductivity, and also offer efficient electrolyte diffusion paths. Density functional theory calculations demonstrate that pyrrolic‐ and pyridinic‐N doping can efficiently promote the adsorption of K + and reduce volume expansion after the insertion of K + , leading to high specific capacity and superior cycling stability of N‐PCNs.