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

Porous 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