<p>The CuNi₂O₄ sample was synthesised using a traditional solid-state reaction method. XRD analysis confirmed the successful formation of the CuNi₂O₄ sample, revealing its cubic crystal structure and crystalline characteristics. Fourier transform infrared spectroscopy (FTIR) is used to identify functional groups in CuNi₂O₄. Raman spectral analysis is used to determine the structural properties of CuNi₂O₄. SEM analysis showed that the synthesised CuNi₂O₄ material displayed a cubical particle morphology. Electrochemical tests demonstrated excellent pseudocapacitive behaviour with a specific capacity of 61.1 mAh/g at a rate of 1 Ag⁻¹. Furthermore, despite a high current density of 5 Ag⁻¹, this electrode demonstrated remarkable cyclability, retaining 88.81% of its capacity and achieving a coulombic efficiency of 90.81% over 10,000 cycles. The symmetric coin cell also displayed pseudocapacitive behaviour, achieving a specific capacity of 30.01 mAh g⁻¹ at a current density of 1 A/g. Furthermore, even at a current density of 5 A/g, this electrode maintained remarkable cycling stability, achieving a capacitance retention of 86.41% and a coulombic efficiency of 89.62% over 5000 cycles. Additionally, it exhibits a specific energy and power of 21 Wh/kg and 699 W/kg. Connecting two devices in series (asymmetric pouch cells) powered blue and green LEDs for over 4&#xa0;min and 3&#xa0;min, respectively. The exceptional performance of CuNi₂O₄ is due to the synergistic interactions between copper and nickel oxides. Thus, these findings indicate that CuNi₂O₄ has considerable promise as an electrode material for supercapacitor applications.</p>