Redox Active Organic Liquids for Energy Storage

Abstract

The necessity to move to renewable energy sources has increased over the last few years. However, to ensure a good transition and effective energy supply, efficient, cheap, and green technologies are required as grid-level storage.1 Redox-Active Organic Materials (ROMs) are a fast-growing research topic in different electrochemical storage devices. Their advantageous characteristics of being formed from highly abundant elements, having a high electrochemical tunability, ease of handling and device processing, and high versatility for a variety of energy storage applications make ROMs attractive.1–3 Redox-Active Liquids (RALs) are themselves a new trend within the category of ROMs because the physical properties of organic liquids are advantageous for some storage devices.4–6 Those advantages include no requirement for materials processing after synthesis, high miscibility and/or high solubility with battery electrolytes, the ability to be used as a solvent themselves without any additional additives,4,5 and the avoidance of surface-related changes e.g., dendrites.7 RALs have been studied as mediators or active materials in the context of different applications such as supercapacitors,6,8 conventional,4,5,9 and hybrid-flow batteries.10,11 In this work, we present the synthesis and physio-chemical characterization of different RALs that can be used in such energy storage devices. The characterization results supported by computational analyses were used to investigate the correlation between the chemical structure and the electrochemical properties of the compounds. The obtained information was then further used to inform the design of further compounds with enhanced electrochemical properties.(1) Schon, T. B.; McAllister, B. T.; Li, P. F.; Seferos, D. S. The Rise of Organic Electrode Materials for Energy Storage. Chem Soc Rev 2016, 45 (22), 6345–6404. https://doi.org/10.1039/c6cs00173d.(2) Kwon, G.; Ko, Y.; Kim, Y.; Kim, K.; Kang, K. Versatile Redox-Active Organic Materials for Rechargeable Energy Storage. Acc Chem Res 2021, 54 (23), 4423–4433. https://doi.org/10.1021/acs.accounts.1c00590.(3) Lee, S.; Hong, J.; Kang, K. Redox-Active Organic Compounds for Future Sustainable Energy Storage System. Advanced Energy Materials. Wiley-VCH Verlag August 1, 2020. https://doi.org/10.1002/aenm.202001445.(4) Zhao, Y.; Zhang, J.; Agarwal, G.; Yu, Z.; Corman, R. E.; Wang, Y.; Robertson, L. A.; Shi, Z.; Doan, H. A.; Ewoldt, R. H.; Shkrob, I. A.; Assary, R. S.; Cheng, L.; Srinivasan, V.; Babinec, S. J.; Zhang, L. TEMPO Allegro: Liquid Catholyte Redoxmers for Nonaqueous Redox Flow Batteries. J Mater Chem A Mater 2021, 9 (31), 16769–16775. https://doi.org/10.1039/d1ta04297a.(5) Robertson, L.; Udin, M. A.; Shlrob, I. A.; Moore, J. S.; Zhang, L. Liquid Redoxmers for Nonaqueous Redox Flow Batteries. ChemSusChem 2023, e202300043. https://doi.org/10.1002/CSSC.202300043.(6) Fontaine, O. A Deeper Understanding of the Electron Transfer Is the Key to the Success of Biredox Ionic Liquids. Energy Storage Mater 2019, 21, 240–245. https://doi.org/10.1016/J.ENSM.2019.06.023.(7) Bao, J.; Li, C.; Zhang, F.; Wang, P.; Zhang, X.; He, P.; Zhou, H. A Liquid Anode of Lithium Biphenyl for Highly Safe Lithium-Air Battery with Hybrid Electrolyte. Batter Supercaps 2020, 3 (8), 708–712. https://doi.org/10.1002/BATT.202000092.(8) Mourad, E.; Coustan, L.; Lannelongue, P.; Zigah, D.; Mehdi, A.; Vioux, A.; Freunberger, S. A.; Favier, F.; Fontaine, O. Biredox Ionic Liquids with Solid-like Redox Density in the Liquid State for High-Energy Supercapacitors. Nature Materials 2016 16:4 2016, 16 (4), 446–453. https://doi.org/10.1038/nmat4808.(9) Chen, H.; Niu, Z.; Zhao, Y. Redox-Active Binary Eutectics: Preparation and Their Electrochemical Properties. Electrochem commun 2021, 126. https://doi.org/10.1016/j.elecom.2021.107028.(10) Shimizu, A.; Takenaka, K.; Handa, N.; Nokami, T.; Itoh, T.; Yoshida, J.-I.; Shimizu, A.; Takenaka, K.; Yoshida, J.; Handa, N.; Nokami, T.; Itoh, T. Liquid Quinones for Solvent-Free Redox Flow Batteries. Advanced Materials 2017, 29 (41), 1606592. https://doi.org/10.1002/ADMA.201606592.(11) Chen, N.; Chen, D.; Wu, J.; Lai, Y.; Chen, D. Polyethylene Glycol Modified Tetrathiafulvalene for High Energy Density Non-Aqueous Catholyte of Hybrid Redox Flow Batteries. Chemical Engineering Journal 2023, 462. https://doi.org/10.1016/j.cej.2023.141996.