Understanding Capacity Fade in Organic Redox-Flow Batteries Using Uncertainty Quantification Techniques and Zero-Dimensional Modeling

Abstract

We introduce the use of Bayesian uncertainty quantification to provide data-informed assessments of the probability of different hypotheses of reactant decay, and to estimate reactant decay parameters from experimental data with quantified uncertainty. As a case study, we use these techniques to extract rate constants describing the nucleophilic attack of quinone-based RFB reactants by water, as measured using in operando ultraviolet-visible spectrophotometry. We then introduce a zero-dimensional electrochemical flow cell model3 which can simulate capacity fade given a reactant decay mechanism and associated parameters, and the cycling protocol. This work has the potential to shed light on the relationship between capacity fade and reactant decay in various organic RFB chemistries, and to enable prediction of the lifetimes of commercial-scale RFBs.(1) Brushett, F. R.; Aziz, M. J.; Rodby, K. E. On Lifetime and Cost of Redox-Active Organics for Aqueous Flow Batteries. ACS Energy Letters 2020, 879-884. DOI: 10.1021/acsenergylett.0c00140. Dieterich, V.; Milshtein, J.; Barton, J.; Carney, T.; Darling, R.; Brushett, F. Estimating the Cost of Organic Battery Active Materials: A Case Study on Anthraquinone Disulfonic Acid. Translational Materials Research 2018.(2) Kwabi, D. G.; Ji, Y.; Aziz, M. J. Electrolyte Lifetime in Aqueous Organic Redox Flow Batteries: A Critical Review. Chemical Reviews 2020.(3) Modak, S.; Kwabi, D. G. A Zero-Dimensional Model for Electrochemical Behavior and Capacity Retention in Organic Flow Cells. Journal of The Electrochemical Society 2021, 168 (8), 080528. DOI: 10.1149/1945-7111/ac1c1f.