Establishing a model redox flow battery is critical to assessing the efficiency of components and the impact of changing variables on battery performance. Furthermore, creating an open-circuit model enables the analysis of electrochemical conductivity testing in proton separators and ion-exchange membranes. The objective of this project is to create an open-circuit model redox flow battery that could be used to methodologically analyze the conductivity of proton separators and ion-exchange membranes. Using a chlorinated polyvinyl chloride (CPVC) base, variable-flow-rate electrolyte pumps, copper current collectors, graphite electrodes, Teflon spacers, and various separators and membranes, one such open-circuit model redox flow battery can be constructed. Using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and chronoamperometry (CA) we can determine the charge transfer resistance, mass transfer resistance, and electronic and ionic conductivity in a flow cell with various supporting redox electrolytes at varying flow rates and at stagnant no-flow conditions. EIS, CV, and CA tests of the model battery can then be used to predict how changes in electrolyte, electrolyte concentration, and flow rate affect the conductivity of proton separators and ion-exchange membranes. This model enables the usage of Nyquist plots to measure the impedance of separators and membranes under varying conditions. Using impedance, changes to components of redox batteries can be measured to improve the efficiency of redox batteries. An understanding of each component in redox batteries can be used to further improve future electrochemical cells.
