Mixture of Anthraquinone Sulfo-Derivatives as an Inexpensive Organic Flow Battery Negolyte: Optimization of Battery Cell

Abstract

Anthraquinone-2,7-disulfonic acid (2,7-AQDS) is a promising organic compound, which is considered as a negolyte for redox flow batteries as well as for other applications. In this work we carried out a well-known reaction of anthraquinone sulfonation to synthesize 2,7-AQDS in mixture with other sulfo-derivatives, namely 2,6-AQDS and 2-AQS. Redox behavior of this mixture was evaluated with cyclic voltammetry and was almost identical to 2,7-AQDS. Mixture was then assessed as a potential negolyte of anthraquinone-bromine redox flow battery. After adjusting membrane-electrode assembly composition (membrane material and flow field)), the cell demonstrated peak power density of 335 mW cm−2 (at SOC 90%) and capacity utilization, capacity retention and energy efficiency of 87.9, 99.6 and 64.2%, respectively. These values are almost identical or even higher than similar values for flow battery with 2,7-AQDS as a negolyte, while the price of mixture is significantly lower. Therefore, this work unveils the promising possibility of using a mixture of crude sulfonated anthraquinone derivatives mixture as an inexpensive negolyte of RFB.

Successful Charge–Discharge Experiments of Anthraquinone-Bromate Flow Battery: First Report

“…The developed single cell of the anthraquinone-bromate flow battery demonstrated the following key characteristics: a power density of 1.08 W cm −2 , an energy density of 16.1 W h L −1 and an energy efficiency that remained stable over 10 charge-discharge cycles and equaled 72%. These preliminary experimental results show that the anthraquinone-bromate concept tends to be a promising inorganic posolyte and organic negolyte couple for use in RFB systems, while its commercial attractiveness can be further improved by using a mixture of anthraquinone sulfo-derivatives instead of pure AQDS [28].…”

“…For instance, a separate energy density of brom posolyte can reach values up to 810 W h kg −1 (1460 W h L −1 ) [2]. Another important fa is that both electrolytes of the proposed energy storage system are inexpensive beca they can be obtained from abundant precursors: for example, for lithium bromate it calcium bromate and lithium hydroxide [27], while for AQDS-anthraquinone and ole [28]. Figure 6 shows the values of coulombic, voltaic and energy efficiencies for each c which remain almost unchanged over ten charge-discharge cycles.…”

“…For instance, a separate energy density of brom posolyte can reach values up to 810 W h kg −1 (1460 W h L −1 ) [2]. Another important fa is that both electrolytes of the proposed energy storage system are inexpensive bec they can be obtained from abundant precursors: for example, for lithium bromate it calcium bromate and lithium hydroxide [27], while for AQDS-anthraquinone and ol [28]. Summarizing, it was shown that the AQDS-bromate approach could provide quite a promising set of main RFB characteristics-namely, power density up to 1 W cm −2 , energy efficiency of about 70% and specific energy density of around 16 W h L −1 .…”

Crossover Flux and Ionic Resistance Metrics in Polysulfide-Permanganate Redox Flow Battery Membranes

“…As the membrane characteristics significantly influence the flow cells performance, there is a need to explore alternative membrane materials that could enhance RFB performance. 19 However, directly testing a wide range of membranes in an RFB takes time and requires large-area membranes. Identifying small-scale membranespecific tests that can evaluate materials with desirable properties for the system can expedite the process of selecting membrane candidates suitable for full-scale testing.…”