Development of a Physics-informed Modeling Framework for Redox-Mediated Flow Batteries

Redox-mediated flow batteries (RMFBs) promise increased energy density through the incorporation of solid active materials into the external tanks, but the operation and design of these devices is challenged by kinetic, thermodynamic, and transport complexities introduced by the solid-mediator reactions. Here, we present a generalized continuum framework and low-dimensional models to describe the coupled dynamics within RMFBs between the flow cell and the tank, which seeks to address questions surrounding how solid-mediator reactions alter system-level behavior. Specifically, we employ continuum-scale conservation relationships to describe the active species concentrations in space and time and mixed potential theory to describe the solid-mediator redox reaction rate within the tank. We demonstrate the framework is capable of qualitatively tracking experimental RMFB-related data extracted from the literature with minimal free parameters. Further analyses provide quantitative insights into the performance regimes for capacity utilization, influence of operating and physical parameters on the concentration and mixed potential profiles within the tank, and dynamic interplay of the tank and flow cell for single- and dual-mediator systems. We anticipate that this framework will serve as a tool for data interpretation, design assessment, and hypothesis generation.