Rate capability and electrolyte concentration: Tuning MnO₂ supercapacitor electrodes through electrodeposition...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Manganese dioxide (MnO2) is a promising pseudocapacitive material for supercapacitors.
• Its low conductivity and hindered ion diffusion limit rate capability.
• Current solutions often involve complex fabrication methods.

Purpose of the Study:

• To develop a simple, cost-effective method to improve MnO2 supercapacitor rate capability.
• To investigate the influence of electrodeposition parameters (time, concentration) on MnO2 properties.
• To optimize MnO2 electrode performance for enhanced charge storage.

Main Methods:

• Potentiostatic cathodic electrodeposition of MnO2 on Ni foam.
• Varied KMnO4 electrolyte concentrations (0.01 M, 0.1 M) and deposition times (1-15 min).
• Characterization using galvanostatic charge-discharge and cyclic voltammetry.

Main Results:

• Electrodeposition at 0.01 M Mn ion concentration and 1 min yielded birnessite δ-MnO2.
• This optimized electrode showed stable specific capacitance (90-100 Fg⁻¹).
• The electrode exhibited minimal rate sensitivity and high rate capability due to porous, thin, layered structure.

Conclusions:

• Simple electrodeposition parameter tuning significantly enhances MnO2 rate capability.
• Birnessite δ-MnO2 formed at low concentration/short time offers superior performance.
• This approach provides a scalable and efficient route for advanced supercapacitor materials.