Abstract

NiCo<inf>₂</inf>O<inf>₄</inf>/NiCo-anchored flake-like hierarchical porous carbon (FHPC) was synthesized using a nitrile-functionalized polybenzoxazine (NBZ) carbon precursor, NaCl as a salt template, and nickel and cobalt as metallic additives. The resulting FHPC has a thickness of 50–200 nm and exhibits micro- and mesoporous structures. NaCl as a salt template transformed the standard type II isotherm of NBZ carbon into a type IV isotherm. Additionally, the average pore diameter increased from 4.19 nm for NBZ carbon to 7.81 nm after annealing at 250 °C. The ordered structure of FHPC can be tuned by adjusting the nickel-to‑cobalt ratio. Higher nickel loading enhanced the ordered structure of the carbon, as confirmed by XRD, Raman, and TEM analysis. NiCo<inf>₂</inf>O<inf>₄</inf>/NiCo nanoparticles form during synthesis and annealing, promoting redox reactions and phase transformations from amorphous to graphitic phases. The annealing process increased the specific capacitance of the samples, with the FHPC-Ni<inf>0.66</inf>Co<inf>0.33</inf>–300 sample reaching 232 F g−1 at a current density of 2 A g−1 and retaining 90.7% of its capacity after 10,000 cycles in a two-electrode system. Therefore, FHPC with NiCo<inf>₂</inf>O<inf>₄</inf>/NiCo nanoparticles is an efficient, cost-effective material for high-performance supercapacitors.