Biomass-derived activated carbon and ZnCo2O4 nanoparticles for high-performance supercapacitors

• Published in: International journal of electrochemical science Vol. 20; no. 11; p. 101172
• Main Authors: Franklin, J. Bosco, Paul, J. Fredrick Jean, Venkatesan, J., Harini, S., Fathima, J. Preethi Rency, Sundaram, S. John, Kaviyarasu, Kasinathan
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2025
• Subjects: Biomass - derived activated carbon; Electrochemical performance; Energy storage materials; Supercapacitor electrodes; ZnCo2O4 nanoparticles; Electrochemical performance; Energy storage materials; Supercapacitor electrodes; Biomass - derived activated carbon; ZnCo2O4 nanoparticles
• ISSN: 1452-3981; 1452-3981
• DOI: 10.1016/j.ijoes.2025.101172

The rapid depletion of fossil fuels and rising energy demands have intensified the search for high-performance energy storage systems such as supercapacitors, which offer superior power density and faster charge–discharge rates compared to conventional batteries. In this study, ZnCo₂O₄ nanoparticles were synthesized via the sol–gel method and further integrated with biomass-derived activated carbon obtained from waste coconut shells. The ZnCo₂O₄/AC composite exhibited a high specific surface area of 463 m²/g with a pore diameter of 2.3 nm, which is significantly higher than the pristine ZnCo₂O₄ that showed 120 m²/g and a pore diameter of 40.3 nm. Electrochemical investigations revealed that the composite delivered an enhanced specific capacitance of 692 F/g at 1 A/g, outperforming ZnCo₂O₄ which recorded 398 F/g. The composite also demonstrated a higher energy density of 221 Wh/kg compared to 127 Wh/kg for ZnCo₂O₄, along with superior cyclic stability by retaining 88 % of its capacitance after 5000 cycles, whereas the pristine material retained 84 %. These improvements are attributed to the synergistic contribution of faradaic and electric double-layer capacitance, facilitated by the uniform dispersion of ZnCo₂O₄ within the porous activated carbon framework. The results highlight the promise of sustainable activated carbon-supported metal oxide composites as advanced electrode materials for next-generation supercapacitor applications. [Display omitted] •A porous structure suitable for the transport of ions, as well as a circular economy product by recycling coconut shells.•The ZnCo2O4/AC composite demonstrated enhanced electrochemical performance because of the combination of faradaic redox reactions from ZnCo2O4 and electric double-layer capacitance from AC.•Biomass-derived activated carbon and ZnCo2O4 nanoparticles for high-performance pseudocapacitive behavior.•As a result of the combined input mass of both components, the overall yield of the ZnCo2O4/AC composite was approximately 90 %.