Efficient Confinement of Solid Capacity Booster Powder as Monolithic Structures for High Performance Redox Mediated Flow Batteries

Abstract

Confinement of solid electroactive materials in the external reservoirs of Redox-Mediated Flow Batteries (RMFB) is of critical importance for the development of this family of battery technologies. Herein, an efficient strategy that is based on a flow-through configuration is proposed. Confinement of all solid particles in a single porous block (so-called monolith) that occupies the entire reservoir brings practical and fundamental advantages. The improved flow distribution across the reservoir for the flow-through configuration enables enhanced kinetics and utilization rates (twice the utilization rate in 20% shorter time). Pressure drop induced by the flow-through configuration is easily reduced by changing the reservoir geometry becoming negligible in comparison to the drop induced by the cell (value for the monolith can be as low as 0.2% of the cell value). Additionally, determination of intrinsic properties of the steady monolith prior to its encapsulation enables knowing textural properties of the reservoir which are required for fundamental aspects. While ferrocyanide – Prussian Blue (redox mediator – solid booster) is used as model system here, the versatility of this strategy enables its implementation in other systems including future chemistries.