Chemical diffusion of electroactive species in ionic compounds: a focus on chemical equilibrium constraint

This work aims at considering the theoretical basis of chemical diffusion of electroactive species in ionic compounds, in particular from the perspective of the chemical equilibrium constraint. For this purpose, first a variety of descriptions on diffusivity are briefly summarised from the viewpoint of driving forces. Then, the equations to stand for the chemical diffusion behaviour are theoretically derived with and without the chemical equilibrium constraint. Finally, the two different situations above are critically compared to explore the origin of chemical diffusion in ionic compounds.