With the merits of having excellent safety, being low cost and being environmentally friendly, zinc-ion hybrid supercapacitors (ZHSCs) are expected to be widely used in large-scale energy storage and flexible wearable devices. However, limited by their sluggish kinetic process, ZHSCs suffer from low-specific capacity and poor cycling stability at high cathode mass loading. Herein, a novel designed oxygen-rich hierarchical porous carbon (HPOC) is obtained by a one-step strategy of synchronous activation and templated for high-performance ZHSCs. The fabricated ZHSCs with HPOCs show significant improvement in Zn-ion storage capability, with a capacity of 209.4 mAh g⁻¹ at 0.1 A g⁻¹ and 108.3 mAh g⁻¹ at 10 A g⁻¹. Additionally, the cycling stability is excellent, with 92.3% retention after 4000 cycles. Furthermore, an impressive areal capacity of 1.7 mAh cm⁻² is achieved, even with a high mass loading of 12.5 mg cm⁻². More importantly, the flexible quasi-solid state ZHSCs also show a considerable capability (183.5 mAh g⁻¹ at 0.1 A g⁻¹) and a high energy density of 178.0 Wh kg⁻¹. This promising result suggests a valuable route to produce functional nanocarbon materials for zinc storage applications.

Developing supercapacitors with high energy density without sacrificing the power density and cycle life has attracted enormous attention. Hierarchical porous graphitic carbons (HPGCs) have been demonstrated to be promising candidates. However, the complicated, energy-intensive synthesis and the difficult post-treatment for the reported synthetic HPGCs have confined the potential for large-scale production and practical applications. In this work, HPGCs have been fabricated by a one-step metallothermic reaction, using magnesium, urea, and zinc acetate dehydrate, showing a distinct hierarchical porous structure with graphitic domains. The assembled supercapacitors exhibit excellent performance at 150 °C, resulting in an energy density of 16 W h kg⁻¹ (with a power density of 500 W kg⁻¹). Moreover, the HPGC shows a high cycling stability (5% loss after 30 000 cycles), and ultrahigh capacitance retention, i.e. 70% at 5 A g⁻¹ and 62% at 10 A g⁻¹ using EMIMBF₄ electrolyte, and 70% at 400 mV s⁻¹ and 77% at 20 A g⁻¹ using 6 mol L⁻¹ KOH electrolyte. Most importantly, the universality of this new metallothermic method of HPGC fabrication has been demonstrated by replacing urea with other chemical substances. Such a facile synthesis may have provided a fresh route to produce HPGCs with excellent supercapacitive performance.