Phase field model of chemical reactions with an example of a solid electrolyte gas sensor

We present a phase field model that tracks species, phase, and charge distribution in electrochemical systems with chemically active species. The 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 for the conservation of mass expression captures the behavior of the chemical reactions through the interface and in the bulk phases. As a demonstration, a solid electrolyte gas sensor is modeled. This simulated gas sensor calculates EMF in response to a changing level of an active gas in the bulk gas phase.

Research highlights
► Phase field of electrochemistry extended to include chemical reactions.
► General model derived to track changes in concentration of ions, interstitial species, as well as electric potential.
► Gas sensor example given as an embodiment of the general model.
► Example gas sensor displays expected Nerst-equation behavior.