Anthraquinone-2,6-disulfamidic acid: an anolyte with low decomposition rates at elevated temperatures

Abstract

A new anthraquinone based anolyte material for redox flow batteries revealed an extraordinarily high stability at elevated electrolyte temperatures.

Leveraging Temperature-Dependent (Electro)Chemical Kinetics for High-Throughput Flow Battery Characterization

“…Borchers et al 42 cycled an aqueous polymeric RFB at 60 • C, but the use of constant current cycling-which results in uncontrolled state of charge (SOC) restriction 24,43 -prevented any quantitative determination of the thermal stability of the redox-active species in an RFB. Rohland et al 44 improved upon the elevated temperature cell by using a volumetrically unbalanced compositionally symmetric cell, 43 with a defined capacity limiting side (CLS) and non-capacity limiting side (NCLS), to cycle an aqueous anthraquinone derivative using constant current constant voltage cycling, at 60 • C. However, by heating only one electrolyte reservoir of the RFB, they may have inadvertently installed a voltage difference between both reservoirs due to the temperature dependence of the reduction potential of a redox couple. This would introduce a cycling asymmetry to the cell open circuit voltage (OCV), but also affect kinetic and mass transport overpotentials on both sides of the cell disproportionately.…”

Evaluation of in situ thermal stability assessment for flow batteries and deeper investigation of the ferrocene co-polymer

“…10,11 With regard to the already published in operando thermal stability studies of organic materials for RFBs, there are only a few contributions reporting RFB anodic organic materials with moderate (0.1-1.0% d −1 ), low (0.02-0.1% d −1 ), and extremely low (#0.02% d −1 ) capacity fade rate (classication by Kwabi et al 4 ) at 40 °C. 21,22 In particular for cathodic organic materials, there have been only a few species with moderate to high capacity fade rate presented. 18,23,24 Consequently, it is of great interest to assess the thermal stability of the currently developed stable RFB organic materials to indicate the promising species, and to better understand the mechanisms of the molecules' decomposition.…”

On the Capacity and Stability of a Biosynthesized Bis-quinone Flow Battery Negolyte

“…Research in aqueous organic redox flow batteries (AORFB) is aiming at overcoming the drawback of lithium batteries and vanadium RFBs for large-scale energy storage, which suffer from electrolyte materials that are expensive, dangerous, environmentally unfriendly, and geographically mined outside of the European Union and therefore may potentially be used in geopolitical conflicts. − With their high availability and biodegradability, organic electrolytes offer a possible solution to abundant and sustainable battery chemistry. , Especially quinones have gained a lot of interest as negolyte materials, most of them being capable of reversible redox chemistry involving two electrons per molecule. , Most of the quinones investigated suffer from low stability and the self-association of the organic molecules has been seen, resulting in the formation of dimers. , Stability issues among quinones mostly occur from degradation, e.g., Michael addition, dimerization, and nucleophilic substitution. , Benzoquinones are the simplest quinone form, having one aromatic ring with two carbonyl groups. These are well known for being prone to Michael addition with nucleophiles such as water, producing hydroquinone by the addition of hydroxyl groups to the unsubstituted carbon atoms. − Besides benzoquinones, the anthraquinones, which have a multicyclic aromatic structure, have attracted the most attention with one of the most investigated quinones as RFB negolyte being the 9,10-anthraquinone-2,7-disulfonic acid (AQDS). ,,, Even AQDS, which shows reasonable stability, possibly due to having two additional aromatic rings, aggregates when dissolved by dimerization with its hydroquinone form producing a quinhydrone, or by dimerizing with another AQDS molecule. , It has been shown that the storage capacity of the self-dimerized AQDS is less than the two electrons per molecule of AQDS that is usually reported .…”