Functionalised biphenylene and graphenylene: excellent choices for supercapacitor electrodes

Area of Science:

• Materials Science
• Condensed Matter Physics
• Electrochemistry

Background:

• Quantum capacitance (CQ) is a key metric for supercapacitor energy storage.
• Biphenylene (BPN) and graphenylene (GPN) are established materials for energy storage applications.

Purpose of the Study:

• Investigate the impact of vacancy defects on the quantum capacitance of BPN and GPN monolayers.
• Correlate structural and electronic property changes with quantum capacitance variations.
• Evaluate the suitability of these materials as anode or cathode components in supercapacitors.

Main Methods:

• Density Functional Theory (DFT) calculations were employed.
• Structural stability, charge distribution, and electronic band structures were analyzed.
• Quantum capacitance and surface charge density were computed for various applied voltages.

Main Results:

• Vacancy defects enhance the density of states (DOS) near the Fermi level in both BPN and GPN due to charge carrier localization.
• This leads to increased quantum capacitance (CQ) at lower potentials, reaching 221 μF cm⁻² for defective BPN.
• Pristine and defective BPN show preference as anode materials.
• GPN and its defective form are identified as superior candidates for symmetric supercapacitors in aqueous systems.

Conclusions:

• Vacancy engineering is a viable strategy to enhance the quantum capacitance of BPN and GPN.
• These modified materials show significant potential for developing high-performance electric double-layer (EDL) supercapacitors.
• The findings offer valuable guidance for designing advanced electrode materials based on BPN and GPN.