Scalable activated carbon/graphene based supercapacitors with improved capacitance retention at high current...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Supercapacitors require advanced electrode materials for improved stability and performance.
• Activated carbon (AC) and graphene are promising materials, but often face challenges in stability and cost-effective production.
• Hybrid materials offer a route to combine the advantages of different carbon-based nanomaterials.

Purpose of the Study:

• To develop scalable and highly stable supercapacitor electrodes.
• To investigate the synergistic effects of combining tea waste-derived activated carbon (AC) with electrochemical exfoliated graphene (EEG).
• To evaluate the electrochemical performance and stability of hybrid AC:EEG electrodes.

Main Methods:

• Activated carbon (AC) was prepared from tea factory waste via a chemical method followed by heat treatment.
• Electrochemical exfoliated graphene (EEG) was produced by direct electrochemical exfoliation of graphite.
• Hybrid electrodes were fabricated by mixing AC and EEG at various ratios (e.g., 70:30).
• Electrochemical performance was tested in coin cells with aqueous electrolyte and scaled up to pouch cells with organic electrolyte.

Main Results:

• The hybrid AC:EEG (70:30) electrode demonstrated a 45% increase in capacitance stability at high currents compared to AC alone.
• The highest gravimetric capacitance achieved was 110 F/g with the 70:30 hybrid electrode in aqueous electrolyte.
• Scaled-up pouch cells using organic electrolyte achieved a gravimetric capacitance of 85 F/g, maintaining good performance.

Conclusions:

• Hybrid electrodes combining AC from tea waste and EEG offer enhanced stability and capacitance.
• The optimized 70:30 AC:EEG ratio provides superior performance for supercapacitor applications.
• The developed hybrid electrodes show potential for scalable energy storage devices using cost-effective materials.