Stable Low-Cost Organic Dye Anolyte for Aqueous Organic Redox Flow Battery

Abstract

Aqueous organic redox flow battery represents a potential solution to significantly reduce the cost of flow batteries. An ideal organic redox active material for flow battery application shall possess good stability in supporting electrolyte, fast redox reaction speed, and low manufacturing cost. In this work, a commercially available dye material was modified and evaluated in aqueous organic redox flow battery as anolyte. The desalted Basic Red 5 dye (d-BR5) exhibited reasonable solubility in acidic supporting electrolyte and stable redox performance. Two aqueous organic redox flow batteries with d-BR5 as anolyte and two different catholytes (4,5dihydroxybenzene-1,3-disulfonic acid (BQDS) and cerium methanesulfonate (Ce(CH 3 SO 3 ) 3 )) were evaluated in this work. The later system reached satisfactory stability in long-term cycling experiments. The cell of d-BR5 and (Ce(CH 3 SO 3 ) 3 ) exhibited an operating voltage ∼ 1.4 V, with 99.9% capacity retention after 200 cycles. The results indicated that organic dye molecules could be potential low-cost active materials for aqueous organic redox flow batteries.

Electrochemical Impedance Spectroscopy Investigation of Organic Redox Reactions (p-Benzoquinone/Hydroquinone Couple)─Implications to Organic Redox Flow Batteries

“…Redox flow batteries (RFBs) are a promising class of large-scale energy storage system toward the integration of renewable energy technologies. − The choice of a redox couple is limited by its solubility, eco-friendliness, cost, stability, and operating voltage window. , All-vanadium RFBs (VRFBs) are the most commercially mature technology because of the use of vanadium at both the electrolytes, mitigating the cross-over issues. , Despite their high power density, large systems suffer from electrolyte imbalance, contaminations, and cell component corrosion. , Furthermore, the limited resources of vanadium, the high expense associated with the cell materials, and the toxicity of using large quantities of soluble vanadium have limited the widespread adoption of the VRFB technology. − To overcome these disadvantages, organic RFB is introduced, where active materials have fast reaction kinetics and are made of cheap and earth-abundant elements. − Unlike the metal ion-based redox couples, organic molecules can be tuned structurally to optimize their redox potential. Despite all the advantages, generic issues of organic molecules adversely affect the performance of the flow cell (adsorption, crystallization, etc.…”

Family Tree for Aqueous Organic Redox Couples for Redox Flow Battery Electrolytes: A Conceptual Review

“…The significantly increased size of the electroactive polymers enables the use of cheap size-exclusion porous membranes, which can reduce the system investment costs. On the other hand, the remaining challenges originate from slower mass transport of redox polymers to the electrode surface and increased electrolyte viscosity [59][60][61][62].…”

“…Wang et al from Nanjing University used a similar system but changed the 7,8 hydroxy phenazine with a modified commercial dye Basic Red 5 [128], to build a cell with ferrocyanide in alkaline media. The same dye has also been used by Lai et al [62], but in their approach, they paired it with cerium in methanesulfonic acid to achieve stable cell operation.…”

Aqueous organic redox flow batteries using naphthoquinone and iodide maintaining pH of electrolytes desirably by adoption of carboxylic acid functionalized carbon nanotube catalyst

“…Remarkably high capacity retention of 99.9% over 200 cycles was also achieved at the current density of 50 mA cm À2 . 33 Hu et al transformed hydrophobic ferrocene into hydrophilic (ferrocenylmethyl) trimethylammonium chloride (FcNCl) dissolved in 4.0 M water and N 1 -ferrocenylmethyl-N 1 ,N 1 , N 2 ,N 2 ,N 2 -pentamethylpropane-1,2-diaminium dibromide (FcN 2 Br 2 ) dissolved in 3.1 M water using ammonium cation and halide anion via one-step N-alkylation reaction, respectively. 25 In addition, to increase their solubility, Na + and K + ions, which were included in ferrocyanide and ferricyanide considered as catholyte, are exchanged into NH 4 + ions by cation exchange reaction.…”