A theoretical study for the Quantum Capacitance Effect of Electric Field on Defective Silicene

Supercapacitors are fully interested in recent years because of their distinctive features such as long life, rapid charging, high-power density, low cost, high power storage and faster release [1-3]. To obtain high capacitance for Supercapacitors, the choice on electrode materials is a key factor and limiting factor in the total capacity of Supercapacitors is their finite quantum capacitance [4]. Silicene is supposed to have potential application of supercapacitor [5].In this study, we have investigated defects and electric field in Silicene sheet and then compared the effects of them on quantum capacitance. All our density functional theory (DFT) Calculations were carried out within the generalized-gradient approximation (GGA) for the exchange correlation functional with the parametrization of Perdew− Burke−Ernzerhof (PBE), as implemented in the Dmol3 package [6,7]. The double numerical plus polarization (DNP) basis set, 4.4 basis file and Monkhorst-Pack k-point mesh of (6×6×1) and (4×4) supercell. To avoid interactions of the silicene sheet with its periodic images, a vacuum gap of 60 Å in the z direction was used. We investigated the effect of absent and present of vertical electric field on defects silicene, in order to improve the quantum capacitance by the way of electric field. On the basis of these results, we expect these results stimulate the further experimental works on silicene and shed some light on silicene-based electrodes for the applications of supercapacitors.