Redox-active organic molecules are promising charge-storage materials for redox-flow batteries (RFBs), but material crossover between the posolyte and negolyte and chemical degradation are limiting factors in the performance of all-organic RFBs. We demonstrate that the bipolar electrochemistry of 1,2,4-benzotriazin-4-yl (Blatter) radicals allows the construction of batteries with symmetrical electrolyte composition. Cyclic voltammetry shows that these radicals also retain reversible bipolar electrochemistry in the presence of water. The redox potentials of derivatives with a C(3)-CF substituent are the least affected by water, and moreover, these compounds show >90% capacity retention after charge/discharge cycling in a static H-cell for 7 days (ca. 100 cycles). Testing these materials in a flow regime at a 0.1 M concentration of the active material confirmed the high cycling stability under conditions relevant for RFB operation and demonstrated that polarity inversion in a symmetrical flow battery may be used to rebalance the cell. Chemical synthesis provides insight in the nature of the charged species by spectroscopy and (for the oxidized state) X-ray crystallography. The stability of these compounds in all three states of charge highlights their potential for application in symmetrical organic redox-flow batteries.
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http://dx.doi.org/10.1021/jacs.1c13543 | DOI Listing |
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January 2025
Council of Scientific and Industrial Research-Central Salt and Marine Chemicals Research Institute (CSIR-CSMCRI), Bhavnagar, Gujarat, 364002, India.
Fluorine-free organic framework polyelectrolyte membranes showing near frictionless ionic conductivities are gaining cognitive insights. However, the co-precipitation of COFs in the membranes often brings trade-offs to commission long-life electrochemical energy storage solutions. Herein, a durable and ionically miscible dual-ion exchange membrane based on triazine organic framework (TOF) is designed for alkaline redox flow batteries (RFB).
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
Department of Chemistry, Missouri University of Science and Technology, Rolla, Missouri 65409, United States.
Nonaqueous redox flow batteries (NARFBs) have been plagued by the lack of appropriate separators to prevent crossover. In this article, the synthesis and characterization of poly(norbornene) (PNB) anion-exchange membranes (AEMs) were studied. PNB is a copolymer of butyl norbornene (BuNB) and bromobutyl norbornene (BrBuNB) with varying amounts of tetramethyl hexadiamine cross-linker.
View Article and Find Full Text PDFACS Omega
January 2025
Department of Chemical and Biological Engineering, The University of British Columbia, 2360 East Mall, Vancouver V6T 1Z3, Canada.
The electrochemical carbon dioxide reduction reaction (CORR) using renewable electricity sources could provide a sustainable solution for generating valuable chemicals, such as formate salt or formic acid. However, an efficient, stable, and scalable electrode generating formate at industrially viable current densities (>100 mA cm) is yet to be developed. Sn or In-based catalysts in gas diffusion electrodes (GDE) can efficiently produce formate.
View Article and Find Full Text PDFACS Appl Energy Mater
January 2025
Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629HZ Delft, The Netherlands.
The decoupled power and energy output of a redox flow battery (RFB) offers a key advantage in long-duration energy storage, crucial for a successful energy transition. Iodide/iodine and hydrogen/water, owing to their fast reaction kinetics, benign nature, and high solubility, provide promising battery chemistry. However, H-I RFBs suffer from low open circuit potentials, iodine crossover, and their multiphase nature.
View Article and Find Full Text PDFChem Asian J
January 2025
Department of Chemistry, Indian Institute of Technology Guwahati, Assam, 781039, INDIA.
Fulfilment of energy demand by utilizing renewable energy sources that do not contribute to the production of greenhouse gases is a step forward in mitigating global warming. However, with the energy sources being intermittent in nature, renewable energy needs to be stored effectively on a grid scale. In this context, the development of redox-flow batteries has emerged as a promising technology where charging and discharging processes are accomplished by the redox shuttling of the electrolytes, namely anolytes and catholytes.
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