Helping to advance the potential of aqueous redox flow batteries - which could provide safe grid-scale energy storage - researchers have engineered a new class of molecules to provide energy storage for this battery type. "We have demonstrated here the ability to pursue and exploit accelerated redox reactions enabled by molecular engineering of materials that would otherwise be unsuitable for flow batteries," they write. The past decade has witnessed the rapid development of redox flow batteries, which are well-suited for large-scale grid storage applications. However, suitable redox molecules, which serve as the energy storage materials for these batteries, are currently limited. Developing such molecules for flow battery applications "is urgently needed to fully unleash the energy storage potential of aqueous organic redox flow batteries," write Bo Hu and T. Leo Liu in a related Perspective. Recent studies have explored using fluorenone (FL) molecules but the performance of FL molecules has not thus far been suitable for durable energy storage. Seeking to advance this space, Ruozhu Feng et al. used molecular engineering to modify 9-fluorenone as the basis for an organic-based redox flow battery. They applied their various molecules in a redox flow battery where the reactions involved reversible ketone hydrogenation and dehydrogenation in an aqueous electrolyte. At room temperature, their approach delivered a high energy efficiency, even when cycled for more than 4 months, as well as good chemical stability. The reactions proceeded at elevated temperatures that are more suitable for real-world applications. "The work by Feng et al. expands the selection of stable organic anolytes and serves as a good example of rational molecular engineering to develop durable electrolyte materials," write Hu and Liu.
###
Journal
Science