Redox flow batteries are a critical technology for large-scale energy storage, offering the promising characteristics of high scalability, design flexibility and decoupled energy and power. In recent years, they have attracted extensive research interest, with significant advances in relevant materials chemistry, performance metrics and characterization. The emerging concepts of hybrid battery design, redox-targeting strategy, photoelectrode integration and organic redox-active materials present new chemistries for cost-effective and sustainable energy storage systems. This Review summarizes the recent development of next-generation redox flow batteries, providing a critical overview of the emerging redox chemistries of active materials from inorganics to organics. We discuss electrochemical characterizations and critical performance assessment considering the intrinsic properties of the active materials and the mechanisms that lead to degradation of energy storage capacity. In particular, we highlight the importance of advanced spectroscopic analysis and computational studies in enabling understanding of relevant mechanisms. We also outline the technical requirements for rational design of innovative materials and electrolytes to stimulate more exciting research and present the prospect of this field from aspects of both fundamental science and practical applications.
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Van Noorden, R. The rechargeable revolution: a better battery. Nature 507, 26–28 (2014).
Dunn, B., Kamath, H. & Tarascon, J.-M. Electrical energy storage for the grid: a battery of choices. Science 334, 928–935 (2011).
Choi, J. W. & Aurbach, D. Promise and reality of post-lithium-ion batteries with high energy densities. Nat. Rev. Mater. 1, 16013 (2016).
Yang, Z. et al. Electrochemical energy storage for green grid. Chem. Rev. 111, 3577–3613 (2011).
Li, B. & Liu, J. Progress and directions in low-cost redox-flow batteries for large-scale energy storage. Natl Sci. Rev. 4, 91–105 (2017).
Dowling, J. A. et al. Role of long-duration energy storage in variable renewable electricity systems. Joule 4, 1907–1928 (2020).
Sepulveda, N. A., Jenkins, J. D., Edington, A., Mallapragada, D. S. & Lester, R. K. The design space for long-duration energy storage in decarbonized power systems. Nat. Energy 6, 506–516 (2021).
Hunter, C. A. et al. Techno-economic analysis of long-duration energy storage and flexible power generation technologies to support high-variable renewable energy grids. Joule 5, 2077–2101 (2021).
Soloveichik, G. L. Flow batteries: current status and trends. Chem. Rev. 115, 11533–11558 (2015).
Park, M., Ryu, J., Wang, W. & Cho, J. Material design and engineering of next-generation flow-battery technologies. Nat. Rev. Mater. 2, 16080 (2017).
Wang, Y., He, P. & Zhou, H. Li-redox flow batteries based on hybrid electrolytes: at the cross road between Li-ion and redox flow batteries. Adv. Energy Mater. 2, 770–779 (2012).
Zhao, Y. et al. A chemistry and material perspective on lithium redox flow batteries towards high-density electrical energy storage. Chem. Soc. Rev. 44, 7968–7996 (2015).
Gong, K., Fang, Q., Gu, S., Li, S. F. Y. & Yan, Y. Nonaqueous redox-flow batteries: organic solvents, supporting electrolytes, and redox pairs. Energy Environ. Sci. 8, 3515–3530 (2015).
Ding, Y., Zhang, C., Zhang, L., Zhou, Y. & Yu, G. Molecular engineering of organic electroactive materials for redox flow batteries. Chem. Soc. Rev. 47, 69–103 (2018). A systematic overview of the development of redox-active organic materials for RFBs.
Xiong, P., Zhang, L., Chen, Y., Peng, S. & Yu, G. A chemistry and microstructure perspective on ion-conducting membranes for redox flow batteries. Angew. Chem. Int. Ed. 60, 24770–24798 (2021).
Li, X., Zhang, H., Mai, Z., Zhang, H. & Vankelecom, I. Ion exchange membranes for vanadium redox flow battery (VRB) applications. Energy Environ. Sci. 4, 1147–1160 (2011).
Yuan, Z., Zhang, H. & Li, X. Ion conducting membranes for aqueous flow battery systems. Chem. Commun. 54, 7570–7588 (2018).
Chen, D. et al. Polybenzimidazole membrane with dual proton transport channels for vanadium flow battery applications. J. Membr. Sci. 586, 202–210 (2019).
Chen, D., Chen, X., Ding, L. & Li, X. Advanced acid-base blend ion exchange membranes with high performance for vanadium flow battery application. J. Membr. Sci. 553, 25–31 (2018).
Peng, S. et al. Polybenzimidazole membranes with nanophase-separated structure induced by non-ionic hydrophilic side chains for vanadium flow batteries. J. Mater. Chem. A 6, 3895–3905 (2018).
Shi, M. et al. Membranes with well-defined selective layer regulated by controlled solvent diffusion for high power density flow battery. Adv. Energy Mater. 10, 2001382 (2020).
Dai, Q. et al. Thin-film composite membrane breaking the trade-off between conductivity and selectivity for a flow battery. Nat. Commun. 11, 13 (2020).
Zhang, L. et al. Enabling graphene-oxide-based membranes for large-scale energy storage by controlling hydrophilic microstructures. Chem 4, 1035–1046 (2018).
Baran, M. J. et al. Design rules for membranes from polymers of intrinsic microporosity for crossover-free aqueous electrochemical devices. Joule 3, 2968–2985 (2019).
Tan, R. et al. Hydrophilic microporous membranes for selective ion separation and flow-battery energy storage. Nat. Mater. 19, 195–202 (2020).
Zuo, P. et al. Sulfonated microporous polymer membranes with fast and selective ion transport for electrochemical energy conversion and storage. Angew. Chem. Int. Ed. 132, 9651–9660 (2020).
Peng, S. et al. Gradient-distributed metal–organic framework–based porous membranes for nonaqueous redox flow batteries. Adv. Energy Mater. 8, 1802533 (2018).
Yuan, J. et al. Membranes in non-aqueous redox flow battery: a review. J. Power Sources 500, 229983 (2021).
Ke, X. et al. Rechargeable redox flow batteries: flow fields, stacks and design considerations. Chem. Soc. Rev. 47, 8721–8743 (2018).
Jiang, H. et al. A high power density and long cycle life vanadium redox flow battery. Energy Stor. Mater. 24, 529–540 (2020).
Mukhopadhyay, A. et al. Mass transfer and reaction kinetic enhanced electrode for high-performance aqueous flow batteries. Adv. Funct. Mater. 29, 1903192 (2019).
Zhang, C. et al. Progress and prospects of next-generation redox flow batteries. Energy Stor. Mater. 15, 324–350 (2018).
Ding, Y., Zhang, C., Zhang, L., Zhou, Y. & Yu, G. Pathways to widespread applications: development of redox flow batteries based on new chemistries. Chem 5, 1964–1987 (2019).
Li, W. & Jin, S. Design principles and developments of integrated solar flow batteries. Acc. Chem. Res. 53, 2611–2621 (2020).
Yan, R. & Wang, Q. Redox-targeting-based flow batteries for large-scale energy storage. Adv. Mater. 30, 1802406 (2018).
Yuan, Z. et al. Advanced materials for zinc-based flow battery: development and challenge. Adv. Mater. 31, 1902025 (2019).
Yuan, Z. et al. Negatively charged nanoporous membrane for a dendrite-free alkaline zinc-based flow battery with long cycle life. Nat. Commun. 9, 3731 (2018).
Duduta, M. et al. Semi-solid lithium rechargeable flow battery. Adv. Energy Mater. 1, 511–516 (2011).
Chen, H. et al. Sulphur-impregnated flow cathode to enable high-energy-density lithium flow batteries. Nat. Commun. 6, 5877 (2015).
Ventosa, E., Amedu, O. & Schuhmann, W. Aqueous mixed-cation semi-solid hybrid-flow batteries. ACS Appl. Energy Mater. 1, 5158–5162 (2018).
Jia, C. et al. High–energy density nonaqueous all redox flow lithium battery enabled with a polymeric membrane. Sci. Adv. 1, e1500886 (2015).
Zhu, Y. G. et al. Unleashing the power and energy of LiFePO4-based redox flow lithium battery with a bifunctional redox mediator. J. Am. Chem. Soc. 139, 6286–6289 (2017).
Chen, Y. et al. A stable and high-capacity redox targeting-based electrolyte for aqueous flow batteries. Joule 3, 2255–2267 (2019).
Zhou, M. et al. Nernstian-potential-driven redox-targeting reactions of battery materials. Chem 3, 1036–1049 (2017).
Zhou, Y. et al. Efficient solar energy harvesting and storage through a robust photocatalyst driving reversible redox reactions. Adv. Mater. 30, 1802294 (2018).
Li, W. et al. High-performance solar flow battery powered by a perovskite/silicon tandem solar cell. Nat. Mater. 19, 1326–1331 (2020).
Luo, J., Hu, B., Hu, M., Zhao, Y. & Liu, T. L. Status and prospects of organic redox flow batteries toward sustainable energy storage. ACS Energy Lett. 4, 2220–2240 (2019).
Li, Z. & Lu, Y. C. Material design of aqueous redox flow batteries: fundamental challenges and mitigation strategies. Adv. Mater. 32, 2002132 (2020).
Reale, E. R., Shrivastava, A. & Smith, K. C. Effect of conductive additives on the transport properties of porous flow-through electrodes with insulative particles and their optimization for Faradaic deionization. Water Res. 165, 114995 (2019).
Murray, A. T., Voskian, S., Schreier, M., Hatton, T. A. & Surendranath, Y. Electrosynthesis of hydrogen peroxide by phase-transfer catalysis. Joule 3, 2942–2954 (2019).
Wang, F. et al. Modular electrochemical synthesis using a redox reservoir paired with independent half-reactions. Joule 5, 149–165 (2021).
Ren, S. et al. Molecular electrocatalysts can mediate fast, selective CO2 reduction in a flow cell. Science 365, 367–369 (2019).
Luo, J., Hu, B., Wu, W., Hu, M. & Liu, T. L. Nickel-catalyzed electrochemical C(sp3)–C(sp2) cross-coupling reactions of benzyl trifluoroborate and organic halides. Angew. Chem. Int. Ed. 60, 6107–6116 (2021).
Mo, Y. et al. Microfluidic electrochemistry for single-electron transfer redox-neutral reactions. Science 368, 1352–1357 (2020).
Novaes, L. F. T. et al. Electrocatalysis as an enabling technology for organic synthesis. Chem. Soc. Rev. 50, 7941–8002 (2021).
Yan, M., Kawamata, Y. & Baran, P. S. Synthetic organic electrochemical methods since 2000: on the verge of a renaissance. Chem. Rev. 117, 13230–13319 (2017).
Winsberg, J., Hagemann, T., Janoschka, T., Hager, M. D. & Schubert, U. S. Redox-flow batteries: from metals to organic redox-active materials. Angew. Chem. Int. Ed. 56, 686–711 (2017).
Hnedkovsky, L., Wood, R. H. & Balashov, V. N. Electrical conductances of aqueous Na2SO4, H2SO4, and their mixtures: limiting equivalent ion conductances, dissociation constants, and speciation to 673 K and 28 MPa. J. Phys. Chem. B 109, 9034–9046 (2005).
Su, L. et al. An investigation of the ionic conductivity and species crossover of lithiated nafion 117 in nonaqueous electrolytes. J. Electrochem. Soc. 163, A5253 (2015).
Aaron, D. et al. Dramatic performance gains in vanadium redox flow batteries through modified cell architecture. J. Power Sources 206, 450–453 (2012).
Suo, L. et al. “Water-in-salt” electrolyte enables high-voltage aqueous lithium-ion chemistries. Science 350, 938–943 (2015).
Wang, W. et al. Recent progress in redox flow battery research and development. Adv. Funct. Mater. 23, 970–986 (2013).
Zhang, L. & Yu, G. Hybrid electrolyte engineering enables safe and wide-temperature redox flow batteries. Angew. Chem. Int. Ed. 60, 15028–15035 (2021).
Shin, S.-H., Yun, S.-H. & Moon, S.-H. A review of current developments in non-aqueous redox flow batteries: characterization of their membranes for design perspective. RSC Adv. 3, 9095–9116 (2013).
Leung, P. et al. Recent developments in organic redox flow batteries: a critical review. J. Power Sources 360, 243–283 (2017).
Xu, K. Nonaqueous liquid electrolytes for lithium-based rechargeable batteries. Chem. Rev. 104, 4303–4418 (2004).
Wei, X. et al. Radical compatibility with nonaqueous electrolytes and its impact on an all-organic redox flow battery. Angew. Chem. Int. Ed. 54, 8684–8687 (2015).
Darling, R. M., Gallagher, K. G., Kowalski, J. A., Ha, S. & Brushett, F. R. Pathways to low-cost electrochemical energy storage: a comparison of aqueous and nonaqueous flow batteries. Energy Environ. Sci. 7, 3459–3477 (2014).
Zhao, Y. et al. A reversible Br2/Br− redox couple in the aqueous phase as a high-performance catholyte for alkali-ion batteries. Energy Environ. Sci. 7, 1990–1995 (2014).
Zhao, Y., Wang, L. & Byon, H. R. High-performance rechargeable lithium-iodine batteries using triiodide/iodide redox couples in an aqueous cathode. Nat. Commun. 4, 1896 (2013).
Chen, H. & Lu, Y.-C. A high-energy-density multiple redox semi-solid-liquid flow battery. Adv. Energy Mater. 6, 1502183 (2016).
Xie, C., Duan, Y., Xu, W., Zhang, H. & Li, X. A low-cost neutral zinc–iron flow battery with high energy density for stationary energy storage. Angew. Chem. Int. Ed. 56, 14953–14957 (2017).
Xie, C. et al. A highly reversible neutral zinc/manganese battery for stationary energy storage. Energy Environ. Sci. 13, 135–143 (2020).
Wei, X. et al. Materials and systems for organic redox flow batteries: status and challenges. ACS Energy Lett. 2, 2187–2204 (2017).
Ding, Y. & Yu, G. A bio-inspired, heavy-metal-free, dual-electrolyte liquid battery towards sustainable energy storage. Angew. Chem. Int. Ed. 55, 4772–4776 (2016).
Lin, K. et al. Alkaline quinone flow battery. Science 349, 1529–1532 (2015).
Huskinson, B. et al. A metal-free organic–inorganic aqueous flow battery. Nature 505, 195–198 (2014).
Wei, X. et al. TEMPO-based catholyte for high-energy density nonaqueous redox flow batteries. Adv. Mater. 26, 7649–7653 (2014).
Liu, T., Wei, X., Nie, Z., Sprenkle, V. & Wang, W. A total organic aqueous redox flow battery employing a low cost and sustainable methyl viologen anolyte and 4-HO-TEMPO catholyte. Adv. Energy Mater. 6, 1501449 (2016). One of the first demonstrations of an aqueous all-organic RFB.
Janoschka, T., Martin, N., Hager, M. D. & Schubert, U. S. An aqueous redox-flow battery with high capacity and power: the TEMPTMA/MV system. Angew. Chem. Int. Ed. 55, 14427–14430 (2016).
Hu, B., DeBruler, C., Rhodes, Z. & Liu, T. L. Long-cycling aqueous organic redox flow battery (AORFB) toward sustainable and safe energy storage. J. Am. Chem. Soc. 139, 1207–1214 (2017).
DeBruler, C. et al. Designer two-electron storage viologen anolyte materials for neutral aqueous organic redox flow batteries. Chem 3, 961–978 (2017).
Luo, J., Hu, B., Debruler, C. & Liu, T. L. A π-conjugation extended viologen as a two-electron storage anolyte for total organic aqueous redox flow batteries. Angew. Chem. Int. Ed. 57, 231–235 (2018).
Milshtein, J. D. et al. High current density, long duration cycling of soluble organic active species for non-aqueous redox flow batteries. Energy Environ. Sci. 9, 3531–3543 (2016).
Kowalski, J. A. et al. A stable two-electron-donating phenothiazine for application in nonaqueous redox flow batteries. J. Mater. Chem. A 5, 24371–24379 (2017).
Hollas, A. et al. A biomimetic high-capacity phenazine-based anolyte for aqueous organic redox flow batteries. Nat. Energy 3, 508–514 (2018). An example of molecular engineering with screening of functional groups en route to a promising phenazine-based anolyte for aqueous RFBs.
Zhang, C. et al. Phenothiazine-based organic catholyte for high-capacity and long-life aqueous redox flow batteries. Adv. Mater. 31, e1901052 (2019). Reports the use of phenothiazine derivative, MB, as a promising positive species in an acidic environment for aqueous RFBs.
Kwon, G. et al. Bio-inspired molecular redesign of a multi-redox catholyte for high-energy non-aqueous organic redox flow batteries. Chem 5, 2642–2656 (2019).
Kwon, G. et al. Multi-redox molecule for high-energy redox flow batteries. Joule 2, 1771–1782 (2018).
Weng, G.-M. et al. Asymmetric allyl-activation of organosulfides for high-energy reversible redox flow batteries. Energy Environ. Sci. 12, 2244–2252 (2019).
Zhang, L., Zhao, B., Zhang, C. & Yu, G. Insights into the redox chemistry of organosulfides towards stable molecule design in nonaqueous energy storage systems. Angew. Chem. Int. Ed. 60, 4322–4328 (2021).
Zhang, L. et al. Reversible redox chemistry in azobenzene-based organic molecules for high-capacity and long-life nonaqueous redox flow batteries. Nat. Commun. 11, 3843 (2020). One of the first demonstrations of the reversible redox chemistry of azobenzene molecules for high-performance non-aqueous RFBs.
Zu, X., Zhang, L., Qian, Y., Zhang, C. & Yu, G. Molecular engineering of azobenzene-based anolytes towards high-capacity aqueous redox flow batteries. Angew. Chem. Int. Ed. 59, 22163–22170 (2020).
Sigel, H. & Martin, R. B. Coordinating properties of the amide bond. Stability and structure of metal ion complexes of peptides and related ligands. Chem. Rev. 82, 385–426 (1982).
Häupler, B., Wild, A. & Schubert, U. S. Carbonyls: powerful organic materials for secondary batteries. Adv. Energy Mater. 5, 1402034 (2015).
Ding, Y., Li, Y. & Yu, G. Exploring bio-inspired quinone-based organic redox flow batteries: a combined experimental and computational study. Chem 1, 790–801 (2016).
Kwabi, D. G. et al. Alkaline quinone flow battery with long lifetime at pH 12. Joule 2, 1894–1906 (2018).
Feng, R. et al. Reversible ketone hydrogenation and dehydrogenation for aqueous organic redox flow batteries. Science 372, 836–840 (2021). Introduces the idea of deprotonation to achieve reversible ketone reaction chemistry for aqueous RFBs.
Liang, Y., Tao, Z. & Chen, J. Organic electrode materials for rechargeable lithium batteries. Adv. Energy Mater. 2, 742–769 (2012).
Duan, W. et al. A symmetric organic-based nonaqueous redox flow battery and its state of charge diagnostics by FTIR. J. Mater. Chem. A 4, 5448–5456 (2016).
Sinclair, N. S., Poe, D., Savinell, R. F., Maginn, E. J. & Wainright, J. S. A nitroxide containing organic molecule in a deep eutectic solvent for flow battery applications. J. Electrochem. Soc. 168, 020527 (2021).
DeBruler, C., Hu, B., Moss, J., Luo, J. & Liu, T. L. A sulfonate-functionalized viologen enabling neutral cation exchange, aqueous organic redox flow batteries toward renewable energy storage. ACS Energy Lett. 3, 663–668 (2018).
Orita, A., Verde, M. G., Sakai, M. & Meng, Y. S. A biomimetic redox flow battery based on flavin mononucleotide. Nat. Commun. 7, 13230 (2016).
Lin, K. et al. A redox-flow battery with an alloxazine-based organic electrolyte. Nat. Energy 1, 16102 (2016).
Li, X. et al. Symmetry-breaking design of an organic iron complex catholyte for a long cyclability aqueous organic redox flow battery. Nat. Energy 6, 873–881 (2021).
Zhao, Y. et al. Sustainable electrical energy storage through the ferrocene/ferrocenium redox reaction in aprotic electrolyte. Angew. Chem. Int. Ed. 126, 11216–11220 (2014). One of the first demonstrations of reversible redox chemistry of organometallic molecules for non-aqueous RFBs.
Wei, X. et al. Towards high-performance nonaqueous redox flow electrolyte via ionic modification of active species. Adv. Energy Mater. 5, 1400678 (2015).
Yu, J. et al. A robust anionic sulfonated ferrocene derivative for pH-neutral aqueous flow battery. Energy Storage Mater. 29, 216–222 (2020).
Cabrera, P. J. et al. Complexes containing redox noninnocent ligands for symmetric, multielectron transfer nonaqueous redox flow batteries. J. Phys. Chem. C 119, 15882–15889 (2015).
Sevov, C. S., Fisher, S. L., Thompson, L. T. & Sanford, M. S. Mechanism-based development of a low-potential, soluble, and cyclable multielectron anolyte for nonaqueous redox flow batteries. J. Am. Chem. Soc. 138, 15378–15384 (2016).
VanGelder, L. E., Pratt, H. D., Anderson, T. M. & Matson, E. M. Surface functionalization of polyoxovanadium clusters: generation of highly soluble charge carriers for nonaqueous energy storage. Chem. Commun. 55, 12247–12250 (2019).
Brushett, F. R., Vaughey, J. T. & Jansen, A. N. An all-organic non-aqueous lithium-ion redox flow battery. Adv. Energy Mater. 2, 1390–1396 (2012).
Duan, W. et al. “Wine-Dark Sea” in an organic flow battery: storing negative charge in 2,1,3-benzothiadiazole radicals leads to improved cyclability. ACS Energy Lett. 2, 1156–1161 (2017).
Huang, J. et al. Liquid catholyte molecules for nonaqueous redox flow batteries. Adv. Energy Mater. 5, 1401782 (2015).
Wang, G. et al. Exploring polycyclic aromatic hydrocarbons as an anolyte for nonaqueous redox flow batteries. J. Mater. Chem. A 6, 13286–13293 (2018).
Wei, X. et al. A high-current, stable nonaqueous organic redox flow battery. ACS Energy Lett. 1, 705–711 (2016).
Zhang, C., Zhang, L., Ding, Y., Guo, X. & Yu, G. Eutectic electrolytes for high-energy-density redox flow batteries. ACS Energy Lett. 3, 2875–2883 (2018).
Zhang, C., Zhang, L. & Yu, G. Eutectic electrolytes as a promising platform for next-generation electrochemical energy storage. Acc. Chem. Res. 53, 1648–1659 (2020).
Chen, J.-J., Symes, M. D. & Cronin, L. Highly reduced and protonated aqueous solutions of [P2W18O62]6− for on-demand hydrogen generation and energy storage. Nat. Chem. 10, 1042–1047 (2018).
Zhang, L., Zhang, C., Ding, Y., Ramirez-Meyers, K. & Yu, G. A low-cost and high-energy hybrid iron-aluminum liquid battery achieved by deep eutectic solvents. Joule 1, 623–633 (2017). One of the first demonstrations of all-deep-eutectic-solvent-based flow batteries with coupling of the reaction of iron and aluminium.
Zhang, C. et al. A sustainable redox-flow battery with an aluminum-based, deep-eutectic-solvent anolyte. Angew. Chem. Int. Ed. 56, 7454–7459 (2017).
Zhang, C. et al. Highly concentrated phthalimide-based anolytes for organic redox flow batteries with enhanced reversibility. Chem 4, 2814–2825 (2018).
Ding, Y. et al. Insights into hydrotropic solubilization for hybrid ion redox flow batteries. ACS Energy Lett. 3, 2641–2648 (2018).
Cong, G., Zhou, Y., Li, Z. & Lu, Y.-C. A highly concentrated catholyte enabled by a low-melting-point ferrocene derivative. ACS Energy Lett. 2, 869–875 (2017).
Shimizu, A. et al. Liquid quinones for solvent-free redox flow batteries. Adv. Mater. 29, 1606592 (2017).
VanGelder, L. E., Cook, T. R. & Matson, E. M. Progress in the design of polyoxovanadate-alkoxides as charge carriers for nonaqueous redox flow batteries. Comments Inorg. Chem. 39, 51–89 (2019).
Palmer, T. C. et al. A comparative review of metal-based charge carriers in nonaqueous flow batteries. ChemSusChem 14, 1214–1228 (2021).
Shrestha, A., Hendriks, K. H., Sigman, M. S., Minteer, S. D. & Sanford, M. S. Realization of an asymmetric non-aqueous redox flow battery through molecular design to minimize active species crossover and decomposition. Chem. Eur. J. 26, 5369–5373 (2020).
Tang, S. et al. Size effect of organosulfur and in situ formed oligomers enables high-utilization Na–organosulfur batteries. Adv. Mater. 33, 2100824 (2021).
Hendriks, K. H. et al. High-performance oligomeric catholytes for effective macromolecular separation in nonaqueous redox flow batteries. ACS Cent. Sci. 4, 189–196 (2018).
Janoschka, T. et al. An aqueous, polymer-based redox-flow battery using non-corrosive, safe, and low-cost materials. Nature 527, 78–81 (2015).
Burgess, M., Moore, J. S. & Rodríguez-López, J. Redox active polymers as soluble nanomaterials for energy storage. Acc. Chem. Res. 49, 2649–2657 (2016).
Winsberg, J. et al. Poly(TEMPO)/zinc hybrid-flow battery: a novel, “green,” high voltage, and safe energy storage system. Adv. Mater. 28, 2238–2243 (2016).
Winsberg, J. et al. TEMPO/phenazine combi-molecule: a redox-active material for symmetric aqueous redox-flow batteries. ACS Energy Lett. 1, 976–980 (2016).
Dieterich, V. et al. Estimating the cost of organic battery active materials: a case study on anthraquinone disulfonic acid. Transl. Mater. Res. 5, 034001 (2018).
Kwabi, D. G., Ji, Y. & Aziz, M. J. Electrolyte lifetime in aqueous organic redox flow batteries: a critical review. Chem. Rev. 120, 6467–6489 (2020).
Elgrishi, N. et al. A practical beginner’s guide to cyclic voltammetry. J. Chem. Educ. 95, 197–206 (2018).
Wang, H. et al. Redox flow batteries: how to determine electrochemical kinetic parameters. ACS Nano 14, 2575–2584 (2020).
Luo, J. et al. Unraveling pH dependent cycling stability of ferricyanide/ferrocyanide in redox flow batteries. Nano Energy 42, 215–221 (2017).
Yao, Y., Lei, J., Shi, Y., Ai, F. & Lu, Y.-C. Assessment methods and performance metrics for redox flow batteries. Nat. Energy 6, 582–588 (2021).
Zhang, J. et al. An all-aqueous redox flow battery with unprecedented energy density. Energy Environ. Sci. 11, 2010–2015 (2018).
Li, Z. & Lu, Y.-C. Polysulfide-based redox flow batteries with long life and low levelized cost enabled by charge-reinforced ion-selective membranes. Nat. Energy 6, 517–528 (2021). Reports a charge-reinforced Nafion membrane to achieve low crossover of polysulfide species, along with demonstrating long-life and low-cost aqueous RFBs.
Wu, M. et al. Extremely stable anthraquinone negolytes synthesized from common precursors. Chem 6, 1432–1442 (2020).
Machado, C. A. et al. Redox flow battery membranes: improving battery performance by leveraging structure–property relationships. ACS Energy Lett. 6, 158–176 (2020).
Lu, W. et al. Porous membranes in secondary battery technologies. Chem. Soc. Rev. 46, 2199–2236 (2017).
Doris, S. E. et al. Macromolecular design strategies for preventing active-material crossover in non-aqueous all-organic redox-flow batteries. Angew. Chem. Int. Ed. 129, 1617–1621 (2017).
Liu, W., Lu, W., Zhang, H. & Li, X. Aqueous flow batteries: research and development. Chem. Eur. J. 25, 1649–1664 (2019).
Goulet, M.-A. & Aziz, M. J. Flow battery molecular reactant stability determined by symmetric cell cycling methods. J. Electrochem. Soc. 165, A1466–A1477 (2018).
Wu, W., Luo, J., Wang, F., Yuan, B. & Liu, T. L. A self-trapping, bipolar viologen bromide electrolyte for redox flow batteries. ACS Energy Lett. 6, 2891–2897 (2021).
Zhao, E. W. et al. In situ NMR metrology reveals reaction mechanisms in redox flow batteries. Nature 579, 224–228 (2020). One of the first demonstrations of in situ NMR spectroscopy to study the detailed mechanism underlying the redox reaction of organic molecules in RFBs.
Wong, A. A., Rubinstein, S. M. & Aziz, M. J. Direct visualization of electrochemical reactions and heterogeneous transport within porous electrodes in operando by fluorescence microscopy. Cell Rep. Phys. Sci. 2, 100388 (2021).
Zang, X. et al. Monitoring the state-of-charge of a vanadium redox flow battery with the acoustic attenuation coefficient: an in operando noninvasive method. Small Methods 3, 1900494 (2019).
Sevov, C. S. et al. Physical organic approach to persistent, cyclable, low-potential electrolytes for flow battery applications. J. Am. Chem. Soc. 139, 2924–2927 (2017).
Yan, Y., Robinson, S. G., Sigman, M. S. & Sanford, M. S. Mechanism-based design of a high-potential catholyte enables a 3.2 V all-organic nonaqueous redox flow battery. J. Am. Chem. Soc. 141, 15301–15306 (2019).
G.Y. acknowledges the financial support from the Welch Foundation award F-1861, Camille Dreyfus Teacher-Scholar Awards and Sloan Research Fellowship. R.F. and W.W. acknowledge the financial support from the US Department of Energy, Office of Electricity (under contract no. 70247) and Energy Storage Materials Initiative, which is a Laboratory-Directed Research and Development project at Pacific Northwest National Laboratory (PNNL). PNNL is a multiprogramme national laboratory operated by Battelle for the US Department of Energy under contract DE-AC05-76RL01830.
The authors declare no competing interests.
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Similar to regeneration, the recovery of active species following membrane crossover.
- Electrode passivation
A decrease in active electrode surface area and an increase in contact and charge transfer resistance. Passivation is generally caused by the deposition and accumulation of side products on the surface of the electrode.
- Hydrotropic effect
The use of suitable organic additives (for example, urea) to help increase the solubility of redox-active solute in aqueous solution through intermolecular interactions (for example, hydrogen bonding).
- Capacity utilization
The percentage of delivered capacity over theoretical capacity.
- Crossover effect
An effect, including, for example, capacity decay and side reactions, that occurs as a result of penetration of the redox species through the membrane.
- Capacity fade rate
The loss in capacity, usually expressed as a percentage, over the total cycle number (% per cycle) or test time (% per day).
The recovery of active species after crossover without sacrificing capacity, which is similar to rebalancing.
- Symmetric cell
A symmetric cell uses the same redox species (but exploits different oxidation states) on both sides of the cell. In the unbalanced configuration, using excess charge for the counter electrolyte minimizes its negative impact on the cell capacity decay.
- Asymmetric cell
The asymmetric full-cell configuration uses different active materials with suitable potential difference in the catholyte and the anolyte, respectively. In a charge-unbalanced cell, one is the working electrolyte (limited charge) and the other serves as the counter electrolyte (excess charge).
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Zhang, L., Feng, R., Wang, W. et al. Emerging chemistries and molecular designs for flow batteries. Nat Rev Chem 6, 524–543 (2022). https://doi.org/10.1038/s41570-022-00394-6