Pore Sieving and Surficial Charge‐Driven Desolvation for High Spatial Charge Density Carbon Cathodes in Zinc‐Ion Hybrid Capacitors

Abstract

Abstract Aqueous zinc‐ion hybrid capacitors (ZIHCs) have emerged as a sustainable energy storage technology. However, the slow diffusion of large solvated Zn 2+ within nanopores and the restriction on the electric double layer (EDL) thickness limit the spatial charge density in carbon electrodes. Herein, multi‐channel porous carbon nanofibers (MC‐PCNFs) are designed with customized porosity and high‐charge‐density interfaces to facilitate rapid [Zn(H 2 O) 6 ] 2+ desolvation and compact EDL formation. The designed hierarchical hollow structure maximizes ion accessibility, while precisely tuned 1.07 nm pores enable direct [Zn(H 2 O) 6 ] 2+ adsorption onto catalytic desolvation sites, significantly reducing the desolvation energy barrier. The resulting ZIHCs achieve a high reversible capacity of 221 mAh g −1 , a battery‐level energy density of 170.2 Wh kg −1 (based on cathode materials), outstanding long‐term cycling stability (>90,000 cycles, 98.7% retention), and practically high areal capacities. Through in/ex situ spectroscopy, theoretical calculations, kinetic analysis, and electrochemical quartz crystal microbalance (EQCM) analysis, the charge storage and interfacial desolvation mechanisms are comprehensively elucidated. This study provides a scalable and effective strategy for catalytic desolvation and high spatial charge density engineering, paving the way for next‐generation high‐energy, long‐cycle‐life ZIHCs.