C<sub>3</sub>N<sub>4</sub> Template-Based N‑Doped\nPorous Carbon Cathode for Zinc-Ion Hybrid Capacitors

Zinc-ion\nhybrid capacitors (ZIHCs), which combine the advantages\nof batteries and supercapacitors, are very competitive in the field\nof advanced energy storage applications. However, their performance\nis limited by carbon cathodes that have a low specific surface area\nand inferior porous structure. Here, we report a N-doped porous carbon\ncathode prepared by high-temperature calcination and chemical activation\nbased on a soft C<sub>3</sub>N<sub>4</sub> template. The as-prepared\nN-doped porous carbon cathode shows a hierarchical nano structure\nwith micropores and mesopores, which can provide additional active\nsites for zinc-ion adsorption, reduce charge-transfer resistance,\nand enhance kinetic performance. The ZIHCs assembled by using this\nN-doped porous carbon cathode exhibits a specific capacitance of 166\nmAh g<sup>–1</sup> at a current density of 0.1 A g<sup>–1</sup>, an energy density of up to 124 Wh kg<sup>–1</sup>, and an\n82.4% capacitance retention after 5000 cycles at a current density\nof 5 A g<sup>–1</sup>, showing a great potential for practical\napplications. Our work provides a way for developing high-performance\nzinc-ion hybrid capacitors.