Nitrogen-doped carbon/NiCo₂S₄ aerogel nanocomposite for solid-state supercapacitors

Abstract

The conversion of biomass into valuable carbon materials reduces environmental pollution and develops effective porous carbon electrodes for energy storage devices. This study aims to prepare a novel composite material consisting of NiCo₂S₄ and chitosan-derived carbon (CNNA) for use in high-performance supercapacitors. The prepared CNNA composite exhibited a high specific surface area of more than 27 m²/g. The CNNA electrode delivered a high specific capacitance of 1282 F.g⁻¹ at 1.0 A.g⁻¹, significantly surpassing that of bare NiCo₂S₄ (340 F.g⁻¹) under the same conditions. Electrochemical analysis revealed that the charge storage behavior involved both capacitive and diffusion-controlled contributions, with the capacitive contribution increasing at higher scan rates. Furthermore, a solid-state asymmetric supercapacitor (ACCS//CNNA) was assembled using CNNA as the positive electrode and chitosan-derived carbon aerogel (ACCS) as the negative electrode. The device achieved a specific capacitance of 199 F.g⁻¹, an energy density of 62 Wh.kg⁻¹, and a power density of 750 W.kg⁻¹, and retained 90.9 % of its initial capacitance after 10,000 charge–discharge cycles. These results clearly demonstrate the synergistic effect of NiCo₂S₄ and N-doped carbon aerogel, highlighting the potential of CNNA as a sustainable and efficient electrode material. Using chitosan in NiCo₂S₄/carbon composites offers advantages, including nitrogen self-doping, the formation of a uniform nanostructure, and enhanced electrochemical performance compared to composites made from other biomass sources.