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Kowalski et al. - A Method for Evaluating Soluble Redox Couple Stability using Microelectrode Voltammetry.pdf (559.05 kB)
A Method for Evaluating Soluble Redox Couple Stability using Microelectrode Voltammetry
Preprints are manuscripts made publicly available before they have been submitted for formal peer review and publication. They might contain new research findings or data. Preprints can be a draft or final version of an author's research but must not have been accepted for publication at the time of submission.
Soluble, redox-active, organic materials hold promise as charge-storage species for flow batteries; however, their stability during extended operation remains a key challenge. While a number of spectroscopic and electrochemical techniques are currently used to probe these complex and often ill-defined decay pathways, each technique has limitations, including accessibility and direct evaluation of practical electrolytes without preparatory steps. Here, we use microelectrode voltammetry to directly observe nonaqueous flow battery electrolytes, simultaneously identifying the rate of charged materials decay (reversible material loss) and total material decay (irreversible material loss). We validate this technique using ferrocene as a stable model redox couple, examine and address sources of error, and finally, demonstrate its capability by assessing the decay of a well-studied and moderately-stable substituted dialkoxybenzene [2,5-di-tert-butyl-1,4-bis(2-methoxyethoxy)benzene]. These results suggest that microelectrodes may have utility for rapid assessment of redox electrolyte state-of-charge and state-of-health, both in-operando and post-mortem.