Field theory for charge transfer kinetics at electrolyte-electrode interface

Charge transfer at the electrolyte-electrode interface is the fundamental kinetic step underlying many applications in electrochemistry, from energy storage to electrocatalysis. The phenomenological Butler-Volmer model has been augmented, and sometimes rationalized, by a microscopic description based on Marcus theory. However, the standard Marcus theory applied in this context adopts a continuum view of electrolytes and cannot describe the spatial variation and saturation of dielectric properties near ions and interfaces.

In this work, we present a statistical field theory for electrolyte mixtures near the interface, which treats solvent size, polarity, and polarization explicitly while incorporating the effects of dielectric saturation and image charge. We evaluate the dependence of ion solvation free energy and solvent reorganization energy on ion-electrode distance, highlighting the importance of resolving the spatial heterogeneity of dielectric properties. Overall, our theory provides a practical tool for quickly screening electrolyte formulations and gives molecular-level insight into ion solvation and charge transfer near an electrode.