Dynamics of Multicomponent Electrolyte Transport Including the Effects of Electrical Double Layers and Redox Reactions*

Multicomponent electrolyte devices see vast use across the fields of energy storage and environmental remediation. Many of these devices use both reduction/oxidation reactions and electrical double layers (EDLs). However, models which account for both effects often assume that the EDLs and reactions are independent. As such, the balance of transport processes which governs the dynamics  of systems that employ both EDLs and reactions remains unclear . 

In this talk, we present a physics-based theoretical framework to capture the dynamics of a model cell that couples the effects of EDLs and electrochemical reactions. We use a perturbation analysis in the thin double layer limit to solve the Poisson-Nernst-Planck equations, which enables us to predict spatial variations in ion concentration and potential. We observe that there are two distinct timescales that control the dynamics: double layer charging and bulk diffusion. Our framework allows for any number of reactions and ions. We discover that reaction rate directly affects EDL formation and the two processes cannot be treated independently. Our model reveals that the thickness of EDLs is dependent on reaction rate, which implies that reactions can be used to control the capacitance of the overall system.