Quantum capacitance tuned flexible supercapacitor by UV-ozone treated defect engineered reduced graphene oxide forest

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Supercapacitors require advanced electrode materials for high power and energy density.
• Reduced graphene oxide (RGO) offers potential due to its unique properties.
• Enhancing RGO's electrochemical performance is crucial for practical applications.

Purpose of the Study:

• To develop a highly power-efficient supercapacitor electrode material.
• To improve the specific energy of reduced graphene oxide (RGO) electrodes.
• To investigate the effect of engineered defects on RGO capacitance.

Main Methods:

• Fabrication of a forest-like 3D RGO structure.
• Introduction of pore-like defects via atomic oxygen etching during UV-ozone treatment.
• Characterization of electrochemical performance and stability.
• Density functional theory (DFT) calculations to understand quantum capacitance.

Main Results:

• Atomic oxygen etching successfully introduced defects, increasing RGO specific capacitance by ~150%.
• The best material achieved 18.87 mF cm⁻² areal capacitance, equivalent to 70 F cm⁻³ volumetric capacitance.
• Fabricated supercapacitors (flexible and non-flexible) demonstrated ultra-high specific power (up to 656.25 mW cm⁻³).
• Devices maintained 90% capacitance after 10K cycles (non-flexible) and 96% after 1K bending cycles (flexible).

Conclusions:

• Engineered defects in RGO significantly enhance supercapacitor performance.
• The 3D RGO forest structure with defects is a promising material for high-power energy storage.
• The developed supercapacitors exhibit excellent power density, energy density, and durability for both rigid and flexible applications.