A 3.2 V Coin Cell Supercapacitor With Ultra‐High Energy Density Using NiCu ₂ O ₄ Nanoparticles as Anodic Material

ABSTRACT In this study, NiCu 2 O 4 nanoparticles were synthesized via the co‐precipitation method and, for the first time, employed as an electrode material for supercapacitor (SC) applications. The synthesized material was analyzed for its morphology, elemental composition, and other properties using standard characterization techniques. The nanoparticles exhibited a cubic structure with uniform distribution, high purity, and an average crystallite size of 72.25 nm. Electrodes were fabricated on a nickel foam (NF) substrate, and electrochemical measurements were conducted in a 6 M KOH electrolyte under ambient conditions. The electrode demonstrated 917.95 F/g of specific capacitance at 10 A/g and only 38.15% reduction in capacitance as the current density increased. Additionally, the electrode retained 87% of its capacitance over 7000 galvanostatic charge–discharge (GCD) cycles. An SC device was also fabricated, exhibiting a specific capacitance of 171.82 F/g at 1 A/g and an energy density of 61.09 Wh/kg. The device achieved a high‐power density of 1.08 kW/kg with 30.15 Wh/kg energy density. A coin cell SC fabricated using this material successfully powered a digital watch, red, and green LEDs for varying durations, demonstrating its potential for practical applications.