Zinc citrate-assisted defect engineering in coal tar pitch-derived porous carbon for high-performance zinc-ion hybrid capacitors.

Authors

Yujuan Li, Xiaoxiao Wang, Xinglei He, Changwang Pan, Chunjiang Jin, Congcong Yang, Wentong Chen

Published in

Nanoscale horizons. Oct 14, 2026. Epub Oct 14, 2026.

Abstract

Aqueous zinc-ion hybrid capacitors (ZIHCs) hold great promise for safe and cost-effective energy storage, yet their practical viability is largely constrained by the insufficient ion-storage capacity of carbonaceous cathodes. Herein, we report a synergistic template-activation strategy to engineer hierarchically porous carbon from coal tar pitch, using zinc citrate as a dual-function self-sacrificial template in conjunction with KOH activation. During pyrolysis, zinc citrate undergoes a distinctive decomposition process in which the in situ generated ZnO nanoparticles serve as a removable hard template, while the concomitantly released gaseous species (CO₂, H₂O, and hydrocarbons) physically blow and chemically etch the carbon matrix. This cooperative mechanism simultaneously creates an interconnected micro-/meso-/macroporous architecture and implants abundant oxygen-containing functionalities, circumventing the need for exogenous templates or post-synthetic surface modification. The optimized ZCPC-1 cathode features a high specific surface area of 1922.1 m² g^-1 and an optimal balance of pore hierarchy and surface polarity. In aqueous ZIHCs, it delivers a reversible capacity of 171.2 mAh g^-1 at 0.2 A g^-1, an energy density of 167.85 Wh kg^-1, and outstanding long-term durability with 82.9% capacity retention over 25 000 cycles. Beyond aqueous systems, the quasi-solid-state flexible device assembled with PASHE gel electrolyte demonstrates a high capacity of 124.54 mAh g^-1 at 0.2 A g^-1, retains 80.5% of its initial capacity after 50 000 cycles at 10 A g^-1, and exhibits an ultralow self-discharge rate of 4.75 mV h^-1, underscoring its practical potential for flexible electronics. This work establishes a conceptually novel and industrially viable approach to upgrading low-cost coal tar pitch into high-performance carbon cathodes through in situ defect engineering and surface chemistry modulation, offering new perspectives for advanced aqueous energy storage systems.

PMID:
42870605
Bibliographic data and abstract were imported from PubMed on 14 Oct 2026.

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