Stone–Wales Decorated Phagraphene: A Potential Candidate for Supercapacitor Electrodes and Thermal Transport

Carbon-based electrical double-layer capacitors or EDLC supercapacitors have recently gained much attention due to their cost-effectiveness, environment friendliness, and stable energy supply. However, the total capacitance of the supercapacitors is limited by the quantum capacitance (QC) of the electrodes. In this work, we have addressed the effect of defect-induced modifications of QC of EDLC supercapacitors by introducing Stone–Wales (SW) defects in pristine phagraphene. The stability of the structure has been confirmed in terms of its dynamical, thermal, and mechanical attributes. A systematic investigation of the electronic and transport properties of SW-decorated phagraphene has been carried out using density functional theory calculations and machine learning approaches. The electronic nature of the structure becomes metallic due to the change in the local symmetry with a modified orbital contribution near the Fermi energy. Besides, a significantly high Debye temperature (2606 K) indicates good thermal transport of the system. The lattice thermal conductivity of the structure was calculated using a machine learning interatomic potential (MLIP) approach. Good thermal conductivity strengthens their potential in next-generation device applications. Interestingly, large specific surface area (SSA), high density of states (DOS) near Fermi energy, and good electrical conductivity of these structures indicate their suitability as supercapacitor electrodes. Considerably high QC and total surface storage charge calculations suggest their applications as anodes in asymmetric supercapacitors. We believe these results will deliver valuable insights into the understanding of carbon-based two-dimensional (2D) metallic structures.