Benchmarking organic active materials for aqueous redox flow batteries in terms of lifetime and cost.

Flow batteries are one option for future, low-cost stationary energy storage. We present a perspective overview of the potential cost of organic active materials for aqueous flow batteries based on a comprehensive mathematical model. The battery capital costs for 38 different organic active materials, as well as the state-of-the-art vanadium system are elucidated. We reveal that only a small number of organic molecules would result in costs close to the vanadium reference system. We identify the most promising candidate as the phenazine 3,3'-(phenazine-1,6-diylbis(azanediyl))dipropionic acid) [1,6-DPAP], suggesting costs even below that of the vanadium reference. Additional cost-saving potential can be expected by mass production of these active materials; major benefits lie in the reduced electrolyte costs as well as power costs, although plant maintenance is a major challenge when applying organic materials. Moreover, this work is designed to be expandable. The developed calculation tool (ReFlowLab) accompanying this publication is open for updates with new data.