Exploring Bio-inspired Quinone-Based Organic Redox Flow Batteries: A Combined Experimental and Computational Study

Modern society requires sustainable energy-storage systems to complement the fast-growing implementation of renewable sources. However, conventional batteries are based on the redox reactions of metals, which are constrained by material abundance, cost, and environmental concerns. As an alternative, quinone-based organic redox species represent one of the most promising electrode materials as a result of features including material sustainability, tailorable properties, and environmental benignity. Here, we report a systematic study on the electrochemical characteristics of quinones for organic flow batteries with a combined experimental and computational method. The redox properties of quinones were found to be strongly dependent on the molecular aromaticity and their electronic structures. In the prototype cell test, a naphthoquinone-based battery delivered a volumetric capacity of 20 Ah L-1 and reached an energy density of 60 Wh L-1. Because quinones play a key role in bio-electrochemical processes, a fundamental understanding of their reaction mechanisms in electrochemical energy-storage devices can pave the path toward bio-inspired sustainable energy technologies.