Related Experiment Video
Updated: Aug 12, 2025

A Protocol for Electrochemical Evaluations and State of Charge Diagnostics of a Symmetric Organic Redox Flow Battery
Published on: February 13, 2017
Sulfonated tryptanthrin anolyte increases performance in pH neutral aqueous redox flow batteries
Daniela Pinheiro1, Marta Pineiro1, J Sérgio Seixas de Melo2
1University of Coimbra, CQC, Department of Chemistry, Rua Larga, Coimbra, Portugal.
Abstract:
Aqueous 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.
More Related Videos
Related Concept Videos
Batteries and Fuel Cells
Formation of Complex Ions
Ion Exchange
Ladder Diagrams: Redox Equilibria
Consider the Fe3+/Fe2+ half-reaction, which has a standard-state potential of +0.771 V. At potentials more positive than +0.771 V, Fe3+ predominates, whereas Fe2+...
Electrolysis
Voltaic/Galvanic Cells
Spontaneous redox reactions occur abundantly in nature. The chemical reaction occurring in a disposable AA battery powering our remote controls is one such example of a spontaneous redox reaction. Another example is the immersion of coiled copper wire into an aqueous silver nitrate solution. The reaction shows a gradual, visually impressive color change from colorless to bright blue and the formation of a grey precipitate on the copper wire. In this experiment,...

