Molecular Insights into Carbon Supercapacitors Based on Room-Temperature Ionic Liquids

The performance of supercapacitors is determined by the electrical double layers (EDLs) formed at electrolyte/electrode interfaces To understand the energy storage mechanism underlying supercapacitors, molecular dynamics (MD) simulations were used to study the capacitive behavior of carbon based supercapacitors with room temperature ionic liquid (RTIL) electrolytes The performance of porous supetcapacitors was found to be correlated with the ion/pore size and applied voltage. supercapacitors composed of RTILs on the outer, positively curved surfaces of onion like carbons (OLCs) or carbon nanotubes (CNTS) exhibited Significant effects on capacitance and the distinctive feature that differential capacitance varies only weakly with voltage. Investigations of temperature influence revealed a positive temperature dependence of capacitance for OLC-based supercapacitors and a weak dependence of capacitance on temperature for CNT-based supercapacitors, in line with experimental observations. Molecular insights into RTIL-based supercapacitors, reviewed in this Perspective, could facilitate the design and development of a new generation of energy storage devices.