(582ar) Kinetics Studies on Redox Flow Battery Electrolytes

Global energy demand continues to grow in the face of decreasing total supply of fossil fuels. Not only is the supply of fossil fuels limited, but the technologies required produce the final products pollute the environment by releasing greenhouse gases. Thus, there is a need to increase availability and decrease the cost of renewable energy technologies, as they are environmental friendly and available in abundance. However, the primary challenge in using renewable energy is storage. For instance, solar energy is only available during the day and unavailable at night. Hence, storage plays an important role for using renewable energy technologies continuously. The redox flow battery (RFB) is an exciting option to harness and store energy for use when it is needed.

 In this poster presentation, we discuss recent studies of RFB electrolyte materials aimed at developing a systematic approach for performing kinetics studies that can be used for characterization of new electrolytes that are currently being developed, and to resolve some of the conflicting data in the literature regarding RFB kinetics. Rotating disk electrode voltammetry was used for these measurements, owing to its effective use in RFB and fuel cell kinetics studies which have been demonstrated in literature. Analytical measurements were carried out under mutually similar conditions to find kinetic and diffusional properties of a set of electrolytes comprising both well-established and nascent flow battery chemistries. We compared kinetics data for a range of model electrode surfaces including platinum, gold and glassy carbon with systematically controlled surface oxidation. We performed Levich analysis to find the diffusivity and Koutecky-Levich analysis to find the reaction rate constant and Tafel slope for each combination of electrolyte and electrode. We further extended this study towards practical measurements using RFB electrolytes at high concentrations to demonstrate the validity of analytical measurements for predicting real battery performance.