Overcoming dichotomy between surface and bulk of electrode: Conducting polymers

Abstract

The surface of the solid-state electrodes constructed from atomic crystals is inherently uncertain due to its chemical unsaturation as its atoms lack the surrounding by the atoms of the same type as in the bulk and its exposure to a different phase. This complicates the evaluation of properties for the high surface area electrodes achieved by porosity. Conducting polymers (CP) are intrinsically conductive molecular solids built from polymeric conjugated molecules without covalent bounds between them. The molecular character of CP implies the translation of identical state from the bulk to the surface of the film without additional surface-induced defects. The absence of covalent bonds between backbones enables the access of external electrolyte to individual chain of CP forming the electrical double layer at the molecular scale. Here we discuss the combination of molecular porosity of CP with its inherent selectivity of ion transport as a special case of porous electrode. We also discuss how the Gibbs phase rule can help in understanding CP electrochemistry.