Quantum capacitance of multi-layered δ-6 borophene: A DFT study

Abstract

First-principles calculation is used to systematically investigate the structure, electronic properties, quantum capacitance (QC), and surface storage charge (σ) of multi-layered δ-6 borophene. δ-6 borophene shows metallic behavior. In this work, the effect of the number of monolayers on QC has been calculated and separated in terms of electrode type. For the thickness of 4 monolayers, the obtained quantum capacitance is 600.36 µF/cm2 (618.07 µF/cm2) for DFT-GGA (DFT-vdW) approximations, respectively, which is higher when compared to graphene layered-based electrodes. From the surface storage charge, 1 monolayer thick and 4 monolayers thick borophene are preferred as cathode type electrode materials, while 2 monolayers thick borophene is an anode type electrode material. This research contributes to a better understanding of an efficient method for increasing the quantum capacitance of borophene-based supercapacitors.