Systematic Design of Active Materials and Membrane Separators for All-Organic Non-Aqueous Redox-Flow Batteries

Redox-flow batteries employ dissolved active materials separated by a semi-permeable membrane to store energy. Cell life and capacity are maximized when active materials can be sequestered in their respective cell compartments at high concentration. Here, I will discuss how the design of the semi-permeable membrane must be considered alongside that for the active materials, whose infinite miscibility with non-aqueous electrolytes allow for high volumetric capacity. The oligomeric design of these active materials makes them sufficiently large to be excluded by a microporous membrane, while maintaining substantially faster electron transfer kinetics than competing polymeric and colloidal active materials. I will discuss how these design features influence charge transfer with the electrode and other attributes that impact the efficiency of the flow cells as they relate to emerging applications in grid-scale energy storage.