A phase field model of electrochemical impedance spectroscopy

A general phase field model for electrochemistry is presented in the context of simulating electrochemical impedance spectroscopy (EIS) experiments. The model tracks species, phases, and charge distribution. Governing partial differential equations are derived from a simple set of assumptions including ideal bulk solution thermodynamics, a method of interpolating between bulk phases, physical balance laws, and the second law of thermodynamics. A source term in the conservation of mass expression captures the behavior of the chemical reactions through the interface and in the bulk phases. Three example systems are given to demonstrate the variety of EIS behavior that can be simulated by this general model. These example systems show two-time constant transport, finite-length diffusion, and constant phase element behavior. Future versions of this model can be used to study the link between EIS and microstructure.