Quantum Capacitance of Sc-doped CNTs as Supercapacitor Electrodes: a DFT Study

Supercapacitors (electrochemical double layer capacitors) and batteries are widely used as electrical energystorage devices. Among them, supercapacitors with high power density, which enables fast charging and dischargingare extremely outstanding [1]. Supercapacitores are classified based on electrodes. Different types of electrodematerials such as carbon-based materials, metal oxides and conductive polymers were used as supercapacitorelectrodes. Among them, carbon materials due to their beneficial physical and chemical properties are mostlyapplied as supercapacitor electrodes [2]. During the recent decades, CNTs due to some specific advantages have alsoreceived increasing attention. Despite of advantage of CNTs-based electrode, major limitation of low quantity ofspecific capacity due to their low quantum capacitance remain [3]. This paper sought to explore variation in quantumcapacitance of carbon nanotubes (CNTs) through doping scandium atom using Density Functional Theory (DFT).Obtained results from density of state (DOS) demonstrated that impurity state are created around the Fermi level(Figure 1a). Quantum capacitance of Sc-doped (6, 6) CNTs in the water stability range (for V= -0٫4 – 0.83) areincreased compared with quantum capacitance of pure (6, 6) CNTs (Figure 2b). The results indicate an asymmetriccapacitance enhancement in Sc-doped CNTs. This is due to changing their electronic structure through dopants Figure 1. Illustrate (a) density of states (DOS) (b) quantum capacitance of Sc-doped CNT (6, 6)

کلیدواژه ها:

Supercapacitor ، DOS ، Quantum capacitance ، DFT