High-Performance Solution-Combustion Synthesized V2O5/NiO Nanocomposites for Supercapacitor Applications: Comparative Electrochemical Evaluation

Abstract

Vanadium pentoxide (V 2 O 5 ), nickel oxide (NiO), and V 2 O 5 /NiO nanocomposites (NCs) with molar ratios of 1:0.5, 1:1, and 1:1.5 were synthesized by a solution-combustion (SC) method and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), highresolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS). Electrochemical properties were examined in 1 M KOH electrolyte through cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic chargedischarge (GCD) using two electrode types: a carbon-paste electrode (CPE) and a nickel-foam electrode (NFE). Among all compositions, the V 2 O 5 /NiO (1:1) NC delivered the highest specific capacitance, achieving 2367 F g -1 on the CPE and 1177 F g -1 on the NFE at 100 mVs-1, with low charge-transfer resistance and excellent cycling stability. The NFE, prepared with 80 wt% active material, 10 wt% polyvinylidene fluoride (PVDF) binder, and 10 wt% Nmethyl-2-pyrrolidone (NMP) solvent, provides a three-dimensional porous architecture that allows a greater fraction of electrochemically active material to participate compared to the CPE. This architecture enhances ion diffusion, electron transport, and rate capability, demonstrating that V 2 O 5 /NiO NCs on an NFE offer a practical pathway to high-energy-density supercapacitors.