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.