Theoretical Studies on the Quantum Capacitance of Two-Dimensional Electrode Materials for Supercapacitors

Abstract

In recent years, supercapacitors have been widely used in the fields of energy, transportation, and industry. Among them, electrical double-layer capacitors (EDLCs) have attracted attention because of their dramatically high power density. With the rapid development of computational methods, theoretical studies on the physical and chemical properties of electrode materials have provided important support for the preparation of EDLCs with higher performance. Besides the widely studied double-layer capacitance (CD), quantum capacitance (CQ), which has long been ignored, is another important factor to improve the total capacitance (CT) of an electrode. In this paper, we survey the recent theoretical progress on the CQ of two-dimensional (2D) electrode materials in EDLCs and classify the electrode materials mainly into graphene-like 2D main group elements and compounds, transition metal carbides/nitrides (MXenes), and transition metal dichalcogenides (TMDs). In addition, we summarize the influence of different modification routes (including doping, metal-adsorption, vacancy, and surface functionalization) on the CQ characteristics in the voltage range of ±0.6 V. Finally, we discuss the current difficulties in the theoretical study of supercapacitor electrode materials and provide our outlook on the future development of EDLCs in the field of energy storage.

High-Performance Ni(II)@Amine-Functionalized Graphene Oxide Composite as Supercapacitor Electrode: Theoretical and Experimental Study

“…47 Both functionalization and compositing are considered effective approaches in enhancing the C Q by tuning the electronic structure of GO. 48 In this part of the research, the effect of amine functionalization via glutamine together with Ni(II) anchoring on the quantum capacitance (C Q ) of GO was investigated theoretically by performing the first-principle study. C Q can be calculated utilizing eq 2:…”

“…47,49 DOS is defined as the number of electron states per unit volume of energy and depends on the charge itself. 50 From eq 4, it can be understood that C Q can be affected by the DOS value. The DOS changes are depicted in Figure 5a as a function of the energy.…”

Recent Advances and Strategies in MXene-Based Electrodes for Supercapacitors: Applications, Challenges and Future Prospects

“…V@PS, Zr@PS, Nb@PS, Hf@PS, and Ta@PS are more suitable for anode materials in ionic/organic systems [ 131 ]. Lin et al [ 132 ] reviewed the theoretical studies on the quantum capacitance of two-dimensional electrode materials for supercapacitors. The larger the specific surface area, the better the energy storage performance of the electrode material demonstrated.…”

EDL Supercapacitor Electrode Performance Analysis of Group-VIB and Group-X Transition Metal Adsorbed and Doped Graphene: A Density Functional Theory Based Comparative Investigation

“…13 However, despite many advantages, one of the major limiting factors of the graphene-based EDL supercapacitor electrode is its low quantum capacitance (C Q ), i.e., the intrinsic capacitance of the electrode material, which degrades the overall interfacial capacitance (C T ) and thereby energy density of the graphene-based EDL supercapacitor. 14,15 Gr is a Dirac Xene material, where both its conduction band minima (CBM) and valence band maxima (VBM) are touching each other at the Fermi level (E F ), i.e., Dirac point with a linear E−k dispersion relationship near E F . The presence of zero band gap in pristine Gr allows electronic states near E F , which are beneficial for improving quantum capacitance.…”