Predicting Viscosity of Electrolyte Solutions for Redox Flow Batteries via Molecular Dynamics

Redox flow batteries (RFBs) represent an evolving technology with significant potential for large-scale energy storage solutions. Yet, the current leading redox active material faces challenges at higher concentrations as it leads to increased electrolyte viscosities, affecting their kinetics. Here, we conducted comprehensive atomistic molecular dynamics (MD) simulations employing the Green-Kubo formalism focusing on highly stable vanadium (4+) bis-hydroxyiminodiacetic (VBH) complex, alkylammonium cations in acetonitrile at different temperatures. Our results depicted lower viscosity as temperature increases. Bulky cation depicted higher viscosity compared to smaller cation. Molecular level insight shows anion-cation interaction increases as the concentration increases while the anion-solvent interaction decreases leading to large and coordinated clusters. These insights would enable the tailored development of electrolyte blends with improved viscosity.