Engineering Oxygen-Rich Heterostructured Porous Carbon for Long Life Cycling Zinc-Ion Hybrid Capacitors

Aqueous zinc-ion hybrid capacitors (ZHCs) are limited by the lack of cathode materials that combine high Zn²⁺ storage capacity with long-term durability. An oxygen-enriched heterostructured porous carbon (LCPC) with an integrated soft-hard carbon architecture has been constructed from low-cost coal tar pitch and renewable lignin through cocarbonization and KOH activation. The resulting material possesses a hierarchical porous network with a specific surface area of 3218.7 m² g^-1 and an oxygen content of 8.14 atom %. When evaluated as a ZHC cathode, LCPC achieves a specific capacity of 165.3 mAh g^-1 at 0.25 A g^-1 and retains 77.1% of its initial capacity after 100,000 cycles, owing to the synergistic combination of a conductive soft carbon framework and a porous hard carbon scaffold. Beyond the demonstrated performance, this work provides insight into the Zn²⁺ storage mechanism in heterostructured porous carbons and establishes a sustainable route to high-performance carbon cathodes for next-generation energy storage.