Zinc-ion capacitors (ZICs) are promising technology for large-scale energy storage by integrating the attributes of supercapacitors and zinc-ion batteries. Unfortunately, the insufficient Zn2+ -storage active sites of carbonaceous cathode materials and the mismatch of pore sizes with charge carriers lead to unsatisfactory Zn2+ storage capability. Herein, new insights for boosting Zn2+ storage capability of activated nitrogen-doped hierarchical porous carbon materials (ANHPC-x) are reported by effectively eliminating the micropore confinement effect and synchronously elevating the utilization of active sites. Therefore, the best-performed ANHPC-2 delivers impressive electrochemical properties for ZICs in terms of excellent capacity (199.1 mAh g-1 ), energy density (155.2 Wh kg-1 ), and durability (65 000 cycles). Systematic ex situ characterizations together with in situ electrochemical quartz crystal microbalance and Raman spectra measurements reveal that the remarkable electrochemical performance is assigned to the synergism of the Zn2+ , H+ , and SO4 2- co-adsorption mechanism and reversible chemical adsorption. Furthermore, the ANHPC-2-based quasi-solid-state ZIC demonstrates excellent electrochemical capability with an ultralong lifespan of up to 100 000 cycles. This work not only provides a promising strategy to improve the Zn2+ storage capability of carbonaceous materials but also sheds lights on charge-storage mechanism and advanced electrode materials' design for ZICs toward practical applications.
Keywords: active site utilization; charge carriers; energy density; micropore confinement effect; zinc-ion capacitors.
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