Zinc-assisted synthesis of edge‐enriched N‐doped porous carbon nanosheets from g-C3N4 for high-performance potassium-ion storage

Abstract

Potassium, owing to its natural abundance and physicochemical similarities to lithium, has emerged as a promising candidate for advanced energy storage technologies. However, the advancement of potassium-ion hybrid capacitors (PIHCs) encounters substantial challenges owing to the larger ionic radius of K⁺ ions, which results in slowed electrochemical kinetics and severe anode volume expansion during cycling. This study presents a facile one-step pyrolysis method for synthesizing two-dimensional edge‐enriched N‐doped porous carbon nanosheets (NPCNs) using zinc as a dual-function catalyst/template. Through a synergistic combination of density functional theory calculations, experimental characterizations, and kinetic analyses, we demonstrate that these architecturally optimized nanosheets effectively accommodate volume strain while maintaining exceptional mechanical stability. The edge-enriched nitrogen doping introduces abundant lone-pair electrons, significantly improving surface-induced capacitive storage. The as-designed NPCNs-2 delivers outstanding electrochemical performance. In potassium-ion batteries, it exhibits a high reversible capacity of 300 mAh g⁻¹ after 300 cycles at 0.2 A g⁻¹ and maintains 175 mAh g⁻¹ even at 1.0 A g⁻¹. When configured into PIHCs, the full cell achieves remarkable energy and power densities (270 Wh kg⁻¹/3000 W kg⁻¹). This work not only reveals fundamental structure-performance correlations, but also provides a scalable synthetic paradigm for the advancement of high-efficiency potassium-based energy storage systems.