Fabrication of asymmetric supercapacitor device with NiCo₂O₄@reduced graphene oxide nanocomposites

In the present work, spinel-like nickel cobalt oxide (NiCo₂O₄) is prepared through a facile and cost-effective co-precipitation method. To enhance the electrochemical characteristics of NiCo₂O₄, the material is incorporated into reduced graphene oxide (rGO) sheets to form a nanocomposite. The FESEM and HRTEM characterizations of the nanocomposite confirms the successful formation of the NiCo₂O₄@rGO. The nitrogen (N₂) adsorption-desorption study reveals the mesoporous nature of both materials, with specific surface areas of 301.18 m² g⁻¹ for NiCo₂O₄@rGO and 54.00 m² g⁻¹ for pristine NiCo₂O₄. Galvanostatic Charge-Discharge (GCD) results indicate that NiCo₂O₄@rGO nanocomposite exhibits nearly four-fold better electrochemical performance compared to pristine NiCo₂O₄. The specific capacity values are 787.17 C g⁻¹ for NiCo₂O₄@rGO and 194.56 C g⁻¹ for NiCo₂O₄ at 1.0 A g⁻¹. The practical utility of the material is showcased through an assembly of asymmetric supercapacitor (ASC) device with the configuration NiCo₂O₄@rGO//Activated Carbon (AC). This device demonstrates high energy density and power density, measured as 46.01 Wh kg⁻¹ and 936.69 W kg⁻¹ at 10 A g⁻¹, and 25.12 Wh kg⁻¹ and 2810.08 W kg⁻¹ at 30 A g⁻¹. The performance of the supercapacitor is further illustrated by illuminating two arrays of LED lights, designed to spell out NITK and KUK. The LEDs illuminate for 10 min and 15 min, respectively, and both arrays together for about 10 min with bright intensity. This work demonstrates the great potential of the NiCo₂O₄@rGO nanocomposite electrodes for energy storage applications with superior performance.