Dielectric and Electrochemical Properties of CoMn ₂ O ₄ Nanoparticles as a Robust Electrode Material for Supercapacitor Application

ABSTRACT

Cobalt manganese oxide (CoMn ₂ O ₄ ) was synthesized as a blackish powder via a solid‐state method. Then, structural characterization was done using x‐ray diffraction (XRD) and scanning electron microscopy (SEM). In XRD, we further analyzed the obtained spectra through Rietveld refinement, which confirmed its crystalline spinel structure, and the Scherrer calculator provided insights into crystallite size. Scanning electron microscopy (SEM) revealed hexagonal agglomerates, suggesting an interconnected morphology with enhanced surface area, advantageous for electrochemical processes. To understand the underlying conduction mechanism, dielectric and impedance spectroscopy studies were performed, revealing bulk‐dominated conduction and a negative temperature coefficient of resistance (NTCR), with charge transport following the correlated barrier hopping (CBH) model. Temperature‐dependent conductivity analysis and modulus studies further clarified hopping distances, energies, and polarization effects. The internal dynamics studied by CIS suggested it as compelling material for an electrode in supercapacitors. Hence, electrochemical investigations were done to highlight the material's potential for energy storage applications: cyclic voltammetry demonstrated pseudocapacitive behavior, while galvanostatic charge‐discharge (GCD) measurements showed a high specific capacitance of 586F/g at a current density of 1A/g. The energy density and power density are ∼52.09 Wh/kg and ∼409.25 W/kg, respectively. To ensure the durability of the synthesized electrode, the cycling stability test was conducted, which gave 87.6% capacitive retention and 90% coulombic efficiency over 4000 cycles. These findings indicate that CoMn ₂ O ₄ combines favorable structural, dielectric, and electrochemical properties, making it a promising candidate for high‐performance supercapacitor electrodes and tunable dielectric materials.