Biomass-derived activated carbon and ZnCo2O4 nanoparticles for high-performance supercapacitors
J. Bosco Franklin, Jean‐François Paul, J. Venkatesan, S. Harini, J. Preethi Rency Fathima, S. John Sundaram, K. Kaviyarasu
Abstract
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.