Electrodeposited MnO2 Thin Film as High–Performance Electrode for Supercapacitor Application

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ABSTRACT

This study presents a facile electrochemical deposition approach for synthesizing MnO₂ thin films directly onto stainless steel (SS) substrates, yielding binder-free nanostructured electrodes for supercapacitor applications. The structural, morphological, and electrochemical characteristics of the deposited MnO₂ films were systematically investigated using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), and Scanning Electron Microscopy (SEM). XRD analysis confirmed the formation of the amorphous birnessite δ-MnO₂ phase, while FTIR spectra exhibited a characteristic Mn-O stretching vibration at 576 cm⁻¹. XPS spectra indicated the presence of Mn-O-Mn and Mn-O-H bonds, confirming the oxidation states of Mn in the thin film. The electrochemical performance was evaluated using cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) measurements in a 1M Na₂SO₄ electrolyte. The as-deposited MnO₂ thin film demonstrated a remarkable specific capacitance of 439 F g⁻¹ at a current density of 0.5 mA cm⁻², along with a power density of 669 W kg⁻¹ and an energy density of 61.02 Wh kg⁻¹. The high electrochemical performance of the MnO₂ thin film can be attributed to its nanostructured morphology and amorphous nature, facilitating efficient charge storage. These findings underscore the suitability of electrodeposited MnO₂ as a promising electrode material for next-generation supercapacitors.

Significance of the Study:

This study demonstrates the potential of electrodeposited MnO₂ thin films as high-performance electrodes for supercapacitors, offering a binder-free and cost-effective alternative to conventional fabrication methods. The findings highlight the advantages of nanostructured MnO₂ in enhancing charge storage, ion diffusion, and electrochemical stability. The results contribute to the development of efficient and scalable energy storage solutions, addressing the growing demand for sustainable supercapacitor technologies.

Summary of the Study:

MnO₂ thin films were successfully electrodeposited onto stainless steel substrates, forming binder-free nanostructured electrodes for supercapacitor applications. Structural characterization confirmed the formation of amorphous birnessite δ-MnO₂, with XRD, FTIR, and XPS analyses validating its composition and bonding states. The electrochemical performance, evaluated through CV and GCD, revealed a high specific capacitance of 439 F g⁻¹, along with excellent energy and power densities. The study underscores the advantages of electrodeposited MnO₂, including its uniform morphology, efficient charge storage, and environmental sustainability. Future research should focus on optimizing deposition conditions, incorporating MnO₂ composites, and assessing long-term cycling stability to further enhance its supercapacitor performance.