The first international workshop on aqueous organic redox flow batteries (AORFB 2025) was held successfully on April 24 and 25, 2025, in Paris. It brought together more than 100 participants, a third of whom came from France and the other two-thirds from the rest of the world. Approximately 30% of the participants were from industry.
Leading researchers in the field were present in Paris, which enabled us to hold an in-depth discussion with our scientific community on the best way to support researchers entering this field of research. The issue was perfectly illustrated by the opening lecture on the inter-laboratory replicability of redox flow battery cell tests (Professor F. R Brushett), and by the lecture listing mistakes to avoid, based on early work in the field by Professor M. J. Aziz’s group.
These two days of discussions focused largely on good experimental practices and the importance of methodological rigor. Without being exhaustive, several speakers addressed these issues explicitly. F. Geneste and M.A. Goulet emphasized the importance of respecting voltage limits during cycling, as well as the importance of maintaining electrolytes at different states of charge for a certain period of time in order to study their stability. S. Guihéneuf (Kemiwatt) emphasized the role of impurities and temperature on the properties of electrolytes, and therefore on battery performance.
C. Stolze presented a comparison of different methods for measuring battery state of health (SOH). P. Peljo and E. Ventosa introduced original experimental setups for measuring the open-circuit voltage (OCV) of each electrolyte using mini-batteries placed upstream and downstream of the main RFB battery. The latter also proposed a new method for periodically rebalancing electrolytes. P. Mazur presented his group’s work on the stability of several compounds and shared experimental tips for working in oxygen-free atmospheric conditions. Finally, L.F. Arenas highlighted the importance of fluid flow velocity and proposed a standardized metric to better understand this aspect.
During the round table discussion held at the end of the day on April 24, the terms standardization and harmonization were raised but no consensus was reached due to the wide variety of chemistries and experimental conditions currently being explored in the field of organic aqueous batteries. The best compromise reached was to establish a practical guideline to help researchers choose the right characterization methods for the level of development of the new electrolytes under consideration.
