3,7-Bis(trifluoromethyl)-N-Ethylphenothiazine: A Highly Soluble, Highly Stable Redox Shuttle and Electro-Active Material for Non-Aqueous Redox Flow Batteries

2016 ◽  
Vol 1 (5) ◽  
pp. 976-980 ◽  
Author(s):  
Jan Winsberg ◽  
Christian Stolze ◽  
Simon Muench ◽  
Ferenc Liedl ◽  
Martin D. Hager ◽  
...  

2017 ◽  
Vol 56 (6) ◽  
pp. 1595-1599 ◽  
Author(s):  
Sean E. Doris ◽  
Ashleigh L. Ward ◽  
Artem Baskin ◽  
Peter D. Frischmann ◽  
Nagarjuna Gavvalapalli ◽  
...  

2021 ◽  
Author(s):  
Jelte Steen ◽  
Jules Nuismer ◽  
Vytautas Eiva ◽  
Albert Wiglema ◽  
Nicolas Daub ◽  
...  

Redox-active organic molecules are promising charge-storage materials for redox-flow batteries (RFBs), but material crossover between posolyte/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 construction of batteries with symmetric electrolyte composition. Cyclic voltammetry shows that these radicals retain reversible bipolar electrochemistry also in the presence of water. The redox potentials of derivatives with a C(3)-CF3 substituent are least affected by water and, moreover, these compounds show >90% capacity retention after charge/discharge cycling in a static H-cell for seven days (ca. 100 cycles). Testing these materials in a flow regime at 0.1 M concentration of active material confirmed the high cycling stability under conditions relevant for RFB operation, and demonstrated that polarity inversion in a symmetric 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 the potential for application in symmetric organic redox-flow batteries.


2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Daniela Pinheiro ◽  
Marta Pineiro ◽  
J. Sérgio Seixas de Melo

AbstractAqueous organic redox flow batteries (AORFBs) hold great promise as low-cost, environmentally friendly and safe alternative energy storage media. Here we present aqueous organometallic and all-organic active materials for RFBs with a water-soluble active material, sulfonated tryptanthrin (TRYP-SO3H), working at a neutral pH and showing long-term stability. Electrochemical measurements show that TRYP-SO3H displays reversible peaks at neutral pH values, allowing its use as an anolyte combined with potassium ferrocyanide or 4,5-dihydroxy-1,3-benzenedisulfonic acid disodium salt monohydrate as catholytes. Single cell tests show reproducible charge-discharge cycles for both catholytes, with significantly improved results for the aqueous all-organic RFB reaching high cell voltage (0.94 V) and high energy efficiencies, stabilized during at least 50 working cycles.


2017 ◽  
Vol 129 (6) ◽  
pp. 1617-1621 ◽  
Author(s):  
Sean E. Doris ◽  
Ashleigh L. Ward ◽  
Artem Baskin ◽  
Peter D. Frischmann ◽  
Nagarjuna Gavvalapalli ◽  
...  

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