Diffusion kinetics of CuCo₂O₄ nanorods for next-generation solid state sodium-ion hybrid supercapacitor

In the current study, we report a straightforward and affordable sol-gel preparation approach for the fabrication of spinel CuCo2O4 nanorods for sodium ion-based hybrid supercapacitor. The morphological and structural analysis shows that appropriate purity nanorods of CuCo2O4 are formed with good stoichiometry. The electrochemical study of CuCo2O4 nanorods reveals that the electrode has highest specific capacitance of 367 F g(-1) at 1 A g(-1) in 1 M Na2SO4 electrolyte. Evaluation of the diffusion kinetics of sodium ions through detailed electrochemical evaluations of cyclic voltammogram (CV) showing the charge storage kinetics of CuCo2O4 is primarily performed through the diffusive limited mechanisms, suggesting the battery-like behavior of CuCo2O4 electrode. Hybrid supercapacitor (HSC) device is fabricated by utilizing CuCo2O4 for positive and reduced graphene oxide (rGO) for negative electrodes material. The polymer gel electrolyte is used in the form of hydrogel membrane made of PVA and Na2SO4, and the HSC device (rGO || CuCo2O4) exhibits energy density of 9.18 Wh kg(-1). Therefore, sodium-ion hybrid supercapacitor electrode materials for this investigation are established using a comprehensive electrochemical kinetics.