Abstract
Redox flow batteries (RFBs) have been identified as a promising large-scale energy storage technology to enable the transition toward a carbon-neutral electricity grid [1]. Among various types of RFBs, non-aqueous redox flow batteries (NRFBs) have the potential to reach the energy density of lithium-ion batteries, while maintaining the advantages of flow systems, including decoupled power and energy rating and efficient long-duration storage [2]. Despite the potential of this transformative technology, poor active material stability poses a fundamental obstacle to NRFB research progress [3-4]. Furthermore, low active material concentrations negate high theoretical energy densities made possible by the wide electrochemical windows of non-aqueous electrolytes [5].
To simultaneously address these issues, we have recently developed an active material based on a molecule known as Amavadin that is naturally occurring in mushrooms of the
Amanita
genus. Biosynthesis of this molecule evolved to bind vanadium selectively and with the highest stability ever reported. Synthetic analogs of Amavadin are synthesized in our lab (vanadium(iv) bis-hydroxyiminodiacetate ([VBH]
2-
)), using inexpensive reagents, at large scale, with high yield and are implemented as a high-stability scaffold for NRFB development [3]. This study aims to elucidate the electrochemical behavior of the introduced NRFB electrolyte at elevated concentrations using an ultramicroelectrode technique. The general trends of critical redox properties of symmetric, [N
XXXX
]
2
[VBH] compounds (x = 1 to 4) are systematically investigated to provide fundamental insight into NRFB electrolyte dynamics. Finally, the performance characteristics of the [VBH]-based electrolytes will be demonstrated using operando flow cell data.
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