Editors' Choice—Electrochemical Impedance Spectroscopy of Flowing Electrosorptive Slurry Electrodes

Abstract

In this paper, an electrochemical impedance spectroscopy (EIS) model for flowing electrosorptive slurry electrodes is developed. The model takes into account the current that is induced by the convection of surface charge carried by particles in the slurry. The use of this model facilitates the in situ characterization of critical slurry electrode properties including the conductivity, the electronic diffusivity, and the contact resistance. When applied to experimental results from an electrochemical flow capacitor (EFC), the model allowed for the discernment of a decrease in the slurry's electronic conductivity with increasing flow rate, an increase in contact resistance, and a rise in the electronic diffusivity. The in situ determination of these properties is essential for the selection of optimal slurry compositions and operating conditions for any electrochemical cell that uses flowing slurry electrodes.