Abstract
There is a strong and growing need for reliable, cost-effective grid storage to support a transition from fossil fuels. Non-aqueous redox-flow batteries (NRFB) are a promising technology to meet this need but they are currently limited by poor stability of solution-phase, charge-carrying metal complexes. A major mechanism of decomposition of these redox electrolytes is substitution of ligands that have weak interactions with substitution-labile metal ions. Presented herein is an approach to mitigate these thermodynamic and kinetic challenges with a naturally occurring compound that is produced biologically. Mushrooms of the genus
Amanita
synthesize a molecule known as Amavadin, in which a vanadium ion is tightly coordinated by a pair of 2,2’-(hydroxyimino)dipropionic acid (HIDPA) ligands. Millions of generations of evolution have optimized the stability of this molecule. As a result, under physiological conditions in which most vanadium compounds would decompose, ligand substitution is suppressed.
The electrochemical properties of redox molecules based on Amavadin as NRFB electrolytes will be presented. This will include data on electrochemical reversibility and stability to deep redox-cycling under various conditions. In addition, we will present the results of computational investigations that have guided ligand-design efforts. These are focused on optimization of the properties of Amavadin-based compounds for application in energy storage devices without losing their extraordinary ability to bind metal ions.