Exploring the performance of pristine and defective silicene and silicene-like XSi3 (X= Al, B, C, N, P) sheets as supercapacitor electrodes: A density functional theory calculation of quantum capacitance

Silicene and silicene-like structures have attracted scientists’ attention because of their novel physical and electronic properties. Recently, they have been studied theoretically as supercapacitor and Li-ion battery electrodes. In this research, the quantum capacitance of pristine and defective silicene and XSi3 silicene-like (X = Al, B, C, N, P) structures calculated using first-principles computations. Our results show that pristine XSi3 sheets have larger quantum capacitance values (cQ = 1500–2000 F/g) in comparison with pristine silicene (cQ = 1200 F/g) and graphene (cQ = 500 F/g). Our partial density of states (PDOS) analysis showed that the origin of large quantum capacitance of XSi3 silicene-like sheets are from 2p and/or 3p orbitals of X and Si atoms. Our data indicated that defects like single vacancy, double vacancy, and Stone−Wales (SW) have not a pronounced effect on quantum capacitance of XSi3 structures. [Display omitted] •Quantum capacitance of XSi3 silicene-like structures is larger than graphene.•Quantum capacitance of different defective silicene systems was calculated by DFT.•DOS analysis was performed to find the origin of quantum capacitance behavior.•Defect formation energy for different defective XSi3 was calculated.•XSi3 silicene-like structures found to be suitable as supercapacitor electrode.