Abstract Carbonaceous zinc-ion capacitors (ZICs) offer inherent advantages for energy storage, yet the role of pore structures in enabling high zinc-ion capacitance remains underexplored. Herein, a dual-molten-salt regulation strategy is employed to derive N/O/S-doped porous carbon nanomaterials, achieving a high specific surface area (SSA) of 2523 m 2 g −1 with ultramicropores (< 0.86 nm) contributing 30.6% of the total SSA. Structural analyses reveal that increasing molten FeCl 3 content yields materials with comparable heteroatom contents and defect structures, but a progressive shift from ultramicropores to mesopores. Crucially, the individual contributions of the pore structure are decoupled by both in situ characterizations and theoretical simulations: The ultramicropores facilitate the desolvation of Zn(H 2 O) 6 2+ (ultramicropore effect), while the hierarchical pores ensure rapid ion transport (hierarchical pore effect). The optimized HHPC-2 delivers a high specific capacitance of 222.6 F g −1 at 1 A g −1 and an energy density of 120.0 Wh kg −1 in ZICs. Intriguingly, its outstanding oxygen reduction reaction catalytic activity enables self-charging upon air exposure after a full discharge, achieving a self-charging rate of 15 mAh g −1 h −1 and recovering 80% of the externally charged capacity in subsequent discharge cycles. This positions the device as highly promising for practical deployment in regions with intermittent grid power supplies.
Zhang et al. (2026) studied this question.