Ultrasonically decorated zinc cobaltate on nanocellulose interface for supercapacitors

The strategic design of energy storage materials from renewable sources has been a keen interest for researchers, especially for energy storage applications. In the present study, ZnCo2O4 and its nanostructures were fabricated along with cellulose nanocrystals (ZnCo2O4@CNC) using the green ultrasonication technique. Structural and morphological examination of composite materials have been investigated by the aid of Field-emission transmission electron microscopy (FE-TEM), X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), and Surface Brunauer-Emmett-Teller (BET) analysis revealing the existence of spherical particles arranged in a controlled nanoscale range (i.e., < 10 nm). The electrochemical properties of ZnCo2O4 and ZnCo2O4@CNC nanocomposites were performed by CV, GCD, and EIS measurements. The ZnCo2O4@CNC electrode reveals a higher specific capacitance value of 346 F/g than its pristine ZnCo2O4 (236 F/g) at 0.5 A/g (current density) in a three-electrode cell assembly. The ZnCo2O4@CNC nanocomposite electrode shows exceptional capacitance with 97% cyclic retention straight after 5000 cycles at 0.5 A/g with an energy density of 15.8 Wh kg−1 at a power density of 138.4 W kg−1, significantly superior to its pristine ZnCo2O4 composite. The increased specific capacitance of nanocomposite materials manifested by the improved surface and morphological properties convince it as capable materials for high-performance electrochemical capacitors.