Zinc-ion hybrid capacitors (ZIHCs) offer safety, high capacity, and low cost. Hierarchical porous carbon cathodes featuring a long-range conductive network are critical for enhancing ZIHC performance. Carbon nanocoils (CNCs) possess a unique long-range helical periodicity and an amorphous-polycrystalline composite structure. The sp3-hybridized carbon defects within CNCs are susceptible to oxidation, which facilitates pore formation and extension, making them promising candidate materials for ZIHC electrodes. In this study, a dual-oxidation strategy of integrating ethanol-induced internal weak oxidation with external strong oxidation in air was employed to fabricate oxygen-doped hierarchically porous carbon nanocoils (EOCNC). The formed pore sizes of EOCNC are primarily distributed across three ranges: 0.4-0.6 nm, 0.6-1.2 nm, and 1.2-2.4 nm. The coexistence of pores in the ranges of 0.6-1.2 nm and 1.2-2.4 nm contributes to reducing the zinc ion diffusion barrier through stepwise desolvation, while the 0.4-0.6 nm ultramicropores hold potential to achieve further desolvation, thereby enhancing the overall capacity. The EOCNC cathode delivers a specific capacity of 147.8 mAh g-1, along with an exceptional rate capability (71.1% capacity retention at 20 A g-1). This study proposes a novel dual internal and external oxidation strategy to fabricate hierarchical porous carbon materials, providing a new pathway for the development of high-performance ZIHC cathodes.
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