Molecular Insights into Carbon Nanotube Supercapacitors: Capacitance Independent of Voltage and Temperature

Abstract

Molecular dynamics (MD) simulations of supercapacitors with single-walled carbon nanotube (SWCNT) electrodes in roomtemperature ionic liquids were performed to investigate the influences of the applied electrical potential, the radius/curvature of SWCNTs, and temperature on their capacitive behavior. It is found that (1) SWCNTsbased supercapacitors exhibit a near-flat capacitance−potential curve, (2) the capacitance increases as the tube radius decreases, and (3) the capacitance depends little on the temperature. We report the first MD study showing the influence of the electrode curvature on the capacitance−potential curve and negligible dependence of temperature on capacitance of tubular electrode. The latter is in good agreement with recent experimental findings and is attributed to the similarity of the electrical double layer (EDL) microstructure with temperature varying from 260 to 400 K. The electrode curvature effect is explained by the dominance of charge overscreening and increased ion density per unit area of electrode surface.

Molecular Modeling of Electrolytes

“…Interestingly, the double-layer structure and capacitance were dependent on the curvature or the atomistic roughness of the surface, especially near the potential of the zero charge. Highly curved surfaces [121,122] or rough surfaces [123] lead to increased capacitance, as shown in Fig. 8.13.…”

Solar‐Energy‐Driven Photoelectrochemical Biosensing Using TiO2 Nanowires

“…This sensitivity is comparable or better than most of the GSH detection methods reported previously. [65] Moreover,t he introduction of N-ethylmaleimide (NEM), at hiol-blocking agent that selectively decomposes GSH, [66] into both the cell extracts and GSH-containing serum reduces the photocurrent change to the background level ( Figure 3e). The IrO 2 -hemin-TiO 2 NW sensor is further studied for the PEC detection of the GSH extracts from av arietyo fl iving cells, such as HeLa cells (a cancer cell line).…”

Classical Density Functional Study on Interfacial Structure and Differential Capacitance of Ionic Liquids near Charged Surfaces

“…This trend qualitatively agrees with MD simulations. 16,17,33 we focused on. The enhanced screening effect can be explained in the first place, by a lower potential drop across more curved space of EDL at same surface charge density.…”

“…14 A series of studies by Feng and co-workers [15][16][17] confirm that DC curve becomes higher and flatter with increasing curvature in cylindrical and spherical electrodes. All findings above could be utilized for the design of more efficient electrical energy storage.…”