Synthesis and characterizations of Al-doped nickel cobalt oxide nanoparticles with superior electrochemical performance for supercapacitor applications

This work investigates the capacitive characteristics of Al-doped nickel cobalt oxide (NiCo₂O₄) nanoparticles by doping them with aluminium at different concentrations (20 mol%, 25 mol%, and 30 mol%) via a hydrothermal technique. The systematic characterizations have been performed. The electrochemical tests are performed to examine the capacitive characteristics. Al-doped NiCo₂O₄ demonstrated a significant OH adsorption capacity for redox processes. With 1 Ag⁻¹ current density, a 25 mol% Al-doped NiCo₂O₄ electrode presented the highest specific capacitance of 1318 Fg⁻¹ compared to NiCo₂O₄ and 20 mol%, 30 mol% of ANCO. The Al-doped NiCo₂O₄@NF//AC in two electrodes displayed exceptional cycling stability over 2500 charge–discharge cycles, retention of 85.13 % of its capacitance at 20 Ag⁻¹. A constructed asymmetric supercapacitor exhibited an outstanding energy density of 18.67 Wh kg⁻¹ at a power density of 2621 Wkg⁻¹. Based on our findings, the 25 mol% Al-doped NiCo₂O₄ exhibited exceptional potential for the application of energy storage systems.