Multi‐Channel Hollow Carbon Nanofibers with Graphene‐Like Shell‐Structure and Ultrahigh Surface Area for High‐Performance Zn‐Ion Hybrid Capacitors

Abstract

AbstractPorous carbon is the most promising cathode material for Zn‐ion hybrid capacitors (ZIHCs), but is limited by insufficient active adsorption sites and slow ion diffusion kinetics during charge storage. Herein, a pore construction‐pore expansion strategy for synthesizing multi‐channel hollow carbon nanofibers (MCHCNF) is proposed, in which the sacrificial template‐induced multi‐channel structure eliminates the diffusion barrier for enhancing ion diffusion kinetics, and the generated ultrahigh surface area and high‐density defective structures effectively increase the quantity of active sites for charge storage. Additionally, a graphene‐like shell structure formed on the carbon nanofiber surface facilitates fast electron transport, and the highly matchable pore size of MCHCNF with electrolyte‐ions favors the accommodation of charge carriers. These advantages lead to the optimized ZIHCs exhibit high capacity (191.4 mAh g−1), high energy (133.1 Wh kg−1), along with outstanding cycling stability (93.0% capacity retention over 15000 cycles). Systematic ex situ characterizations reveal that the dual‐adsorption of anions and cations synergistically ensures the outstanding electrochemical performance, highlighting the importance of the highly‐developed porous structure of MCHCNF. This work not only provides a promising strategy for improving the capacitive capability of porous materials but also sheds light on charge storage mechanisms and rational design for advanced energy storage devices.