Fabrication of dual heteroatom-doped graphitic carbon from waste sponge with "killing two birds with one stone" strategy for advanced aqueous zinc–ion hybrid capacitors.

The N, S dual-doped porous graphitic carbon materials with the high graphitization degree were synthesized from the light fraction of coal tar pitch and waste sponge through a facile "killing two birds with one stone" process. The suitable N and S doping not only can provide extra electroactive sites, but also can improve the storage capacity of Zn ions through the decrease in E a value for LC-750 cathode. [Display omitted] • The N, S dual-doped porous graphitic carbon is prepared via a "killing two birds with one stone" strategy. • The LC-750 exhibits superior pore structures and high graphitization degree. • The LC-750 cathode shows high capacity and excellent performance in AZICs. • The N and S incorporation enhances the Zn2+ adsorption ability and charge transfer behavior. Emerging aqueous zinc–ion hybrid capacitors (AZICs) are considered a promising energy storage because of their superior electrochemical performance. The pore structure, suitable heteroatom content, and graphitization degree (GD) of carbon-based cathodes significantly influence the electrochemical performance of AZICs. The N, S dual-doped porous graphitic carbon materials (LC-750) with the combined characteristics of high GD (1.11) and large specific surface area (1678.38 m2 g−1) are successfully developed by a facile "killing two birds with one stone" strategy using K 3 Fe(C 2 O 4) 3 ·3H 2 O as the activating and graphitizing agent, and waste sponge (WS) and coal tar pitch (CTP) as the heteroatom and carbon resource, respectively. Results show that the LC-750 cathode displays high capacities of 185.3 and 95.2 mAh g−1 at 0.2 and 10 A g−1. Specifically, the assembled LC-750//Zn capacitor can offer a maximal energy density of 119.5 Wh kg−1, a power density of 20.3 kW kg−1, and a capacity retention of 87.8% after 15,000 cycles at 10 A g−1. Density functional theory simulations demonstrate that N and S dual-doping can promote the adsorption kinetics of Zn ions. This design strategy is a feasible and cost-effective method for the preparation of dual heteroatom-doped graphitic carbon electrodes, which enables recycling of WS and CTP into high-valued products. [ABSTRACT FROM AUTHOR]