Classical theory of electron-ion correlations at electrochemical interfaces: Closing the circuit from double-layer charging to ion adsorption

Abstract

The electric double layer (EDL) that forms at the interface between metals and ionic solutions is at the heart of various energy technologies. Recent experimental data have challenged our traditional understanding of the EDL charging behavior, which is based on mean-field Gouy-Chapman-Stern-type (GCS) models. In this article, we present a classical theory for the EDL, derived from first-principles statistical mechanics, that accounts for electron-ion correlation effects using the method of image charges and systematically extends beyond the mean-field level. Such electron-ion correlations introduce an additional interaction between the metal surface and electrolyte ions, significantly altering the EDL structure. Our theory, valid in the limit of dilute electrolyte solutions and weakly charged metal surfaces, achieves quantitative agreement with experimental capacitance data across a wide range of electrode materials and electrolyte solvents, and thus resolves long-standing questions on the origin of discrepancies to GCS predictions. Thereby, the framework conceptually unifies the processes of double-layer charging and ion adsorption (electrosorption), which are typically considered as distinct phenomena, but are shown to be manifestations of the same fundamental electrostatic principles.

References in corpus (14)

• Double layer in ionic liquids: Overscreening vs. crowding
• Beyond Poisson-Boltzmann: Fluctuations and Correlations
• Interfacial layering in the electric double layer of ionic liquids
• Variational approach for electrolyte solutions: from dielectric interfaces to charged nanopores
• Theory of volumetric capacitance of an electric double-layer supercapacitor
• Capacitance of the Double Layer Formed at the Metal/Ionic-Conductor Interface: How Large Can It Be?
• On the theoretical description of weakly charged surfaces
• Effective Field Theory for Highly Ionized Plasmas
• Anomalously large capacitance of an ionic liquid described by the restricted primitive model
• Ionic profiles close to dielectric discontinuities: Specific ion-surface interactions
• Subtleties on energy calculations in the image method
• Image charge effects under metal and dieletric boundary conditions
• First-principles theory of electrochemical capacitance
• Variational functional theory for coulombic correlations in the electric double layer