N‐Doped Porous Carbon Based on Anion and Cation Storage Chemistry for High‐Energy and Power‐Density Zinc Ion Capacitor

Abstract

Zinc ion hybrid capacitors (ZIHCs) show promise for large‐scale energy storage because of their low cost, highly intrinsic safety, and eco‐friendliness. However, their energy density has been limited by the lack of advanced cathodes. Herein, a high‐capacity cathode material named N‐doped porous carbon (CFeN‐2) is introduced for ZIHCs. CFeN‐2, synthesized through the annealing of coal pitch with FeCl3·6H2O as a catalytic activator and melamine as a nitrogen source, exhibits significant N content (10.95 wt%), a large surface area (1037.66 m2 g−1), abundant lattice defects and ultrahigh microporosity. These characteristics, validated through theoretical simulations and experimental tests, enable a dual‐ion energy storage mechanism involving Zn2+ ions and CF3SO3− anions for CFeN‐2. When used as a cathode in ZIHCs, CFeN‐2 achieves a high‐energy density of 142.5 W h kg−1 and a high‐power density of 9500.1 W kg−1. Furthermore, using CFeN‐2 ZIHCs demonstrate exceptional performance with 77% capacity retention and nearly 100% coulombic efficiency after 10 000 cycles at 10 A g−1, showcasing substantially superior performance to current ZIHCs. This study offers a pathway for developing high‐energy and high‐power cathodes derived from coal pitch carbon for ZIHC applications.