Eco-Friendly and High Performance Supercapacitors for Elevated Temperature Applications Using Recycled Tea Leaves.

Area of Science:

• Materials Science
• Electrochemistry
• Sustainable Energy

Background:

• Development of cost-effective and sustainable electrode materials for energy storage devices is crucial.
• Valorization of waste materials like used tea leaves offers a promising route for creating advanced carbon materials.
• Supercapacitors require electrode materials with high surface area and excellent electrochemical properties for efficient energy storage.

Purpose of the Study:

• To investigate the preparation of high-surface-area carbon from used tea leaves for supercapacitor applications.
• To control the surface area and pore size of the derived carbon by optimizing the activation process.
• To evaluate the electrochemical performance and stability of supercapacitors fabricated using tea leaf-derived carbon electrodes.

Main Methods:

• Carbonization of used tea leaves followed by activation using potassium hydroxide (KOH).
• Characterization of the derived carbon material, including surface area and pore size analysis.
• Fabrication and electrochemical testing of symmetrical supercapacitor devices using the synthesized electrodes.

Main Results:

• Achieved a maximum surface area of 2532 m² g⁻¹, significantly higher than unactivated tea leaves (3.6 m² g⁻¹).
• Demonstrated a maximum specific capacitance of 292 F g⁻¹ in 3 m KOH electrolyte, with nearly 100% capacitance retention over 5000 cycles.
• Supercapacitor devices exhibited high rate stability (95% retention up to 12 mA cm⁻²) and improved charge storage with increasing temperature (35% from 10 to 80 °C).

Conclusions:

• Used tea leaves are a viable precursor for producing high-performance, environmentally friendly carbon materials for supercapacitors.
• The electrochemical performance is influenced by electrolyte ion size and activation conditions.
• The developed supercapacitors offer excellent cyclic stability, rate capability, and temperature performance at a low cost.