Regulating MXene Functionalization and Oxidation for High-Rate, High Mass-Loading Supercapacitors

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• MXene electrodes face performance limitations in supercapacitors due to degradation at higher thicknesses and mass loadings.
• Balancing surface functionalization and oxidation is crucial for MXene chemistry regulation.

Purpose of the Study:

• To develop a controlled redox environment to overcome the trade-off between surface functionalization and oxidation in MXene chemistry.
• To engineer high-performance MXene-based electrodes for high-energy supercapacitors.

Main Methods:

• A urea-assisted hydrothermal process was used to remove -F terminations and create N-doped 3D MXene hydrogels.
• L-ascorbic acid was employed as an antioxidant to suppress structural oxidation and enhance stability.
• Electrode performance was evaluated at various mass loadings and current densities.

Main Results:

• Optimized MXene electrodes demonstrated superior rate capability and cycling stability under high mass loadings.
• At 10.97 mg cm⁻², a specific capacitance of 597 F g⁻¹ at 1 A g⁻¹ was achieved with 69.66% retention at 50 A g⁻¹.
• Even at 108.64 mg cm⁻², 44.50% capacitance retention was observed from 1 to 20 A g⁻¹.

Conclusions:

• The developed strategy effectively regulates MXene chemistry via reaction pathway control.
• This enables the practical operation of high-performance MXene electrodes at commercially relevant mass loadings.
• The findings pave the way for advanced MXene-based energy storage devices.