All-Organic Storage Solids and Redox Shuttles for Redox-Targeting Flow Batteries

Abstract

Large-scale integration of renewable energies into the electrical grid will remain limited until high-capacity storage systems are developed to modulate the intermittency of harvestable sources. This work details the bottom-up design of all-organic materials and shuttles for application in high-capacity storage systems using redox chemistries of both heterogeneous and homogeneous compounds. Tailored heterogeneous polymers are cycled through redox-targeting reactions with a solvated redox-active compound. This hybrid battery, termed a redox-targeting flow battery (RTFB), merges the scalability and tunability of organic flow batteries with the energy density of solid-state batteries. Tuning steric and electronic properties of organic shuttles and solids for high capacities and voltaic efficiencies required the development of an accessible technique to monitor the state of charge (SOC) of the polymer as a function of time. Guided by these studies, we demonstrate RTFB cycling with high SOCs (>85%), high polymer utilization (>90%), and high voltaic efficiencies (>75%).