Molecular Theory of Solvation and Electrical Double Layer in Nanoporous Carbon Electrodes

Abstract

Electrical double layer (EDL) in a nanoporous electrode is very different from a planar electrochemical capacitor. The statistical-mechanical, Replica RISM-KH-VM molecular theory for electrolyte solution sorbed in disordered nanoporous materials provides full microscopic details of the solvation structure and thermodynamics and electrochemical properties averaged over the thermal motion of sorbed solution and over quenched morphology of host nanoporous material. The method reveals the molecular mechanisms and driving forces of sorption of electrolyte solution in a nanoporous carbon electrode which are drastically different from the electrical double layer in electrolyte solution at a planar electrode. These include nanoporous confinement morphology and external charge, size and chemical specificities of solvent and electrolyte, osmotic forces, the internal EDL at the surface of nanopores and the external EDL at the contact with bulk solution. The interplay of these factors determines the efficiency of an electrosorption cell and the specific capacitance of the electrochemical supercapacitor.