A key advance for clean energy storage
The race towards more sustainable energy storage solutions takes a new step with recent work carried out by Bordeaux researchers, in collaboration with a Japanese team. Their results, published in the Journal of Power Sourceslay the foundations for a better understanding of organic flow batteries – a promising technology for the energy transition.
What is a flow battery?
Unlike conventional batteries (such as lithium ones), flow batteries store energy in electrolytic liquids that circulate between two reservoirs before being pumped into an electrochemical cell where the chemical energy is converted into electricity. This architecture allows separate storage capacity and powermaking this type of battery particularly interesting for large-scale storage installations, such as electricity networks or renewable systems.
Historically, these batteries used inorganic electrolytes – often based on heavy metals such as vanadium – which poses constraints of cost, toxicity and sustainability. This is why the scientific community is increasingly interested in safer and more environmentally friendly alternatives.
An organic and biocompatible solution
The innovation highlighted by the researchers focuses on the use of biocompatible organic electrochemical couplesin particular the duo methyl-viologen / 4‑hydroxy-TEMPO (MV / 4‑HO-TEMPO). These molecules, simpler to synthesize and less toxic than traditional electrolytes, open the way to more sustainable flow batteries – both economically and environmentally.
To optimize these new systems, it is essential to understand precisely how reactions take place at the interface between the electrolyte and the electrodes. This is where the research team from the Institute of Mechanics and Engineering of Bordeaux (I2M, CNRS / Arts et Métiers / University of Bordeaux) comes in, in partnership with the University of Tokyo.
Innovative imaging for more efficient batteries
Scientists have adapted a spectroelectrochemical imaging technique which makes it possible to map in detail the concentration variations and kinetic constants of organic electrolytes within a microchip. Using a microscope and a camera, they modulate the applied voltage and film the evolution of the reagents, making it possible to link optical measurements to real electrical performance.
These maps provide valuable information for adjust the cell design and operating conditions future prototypes. In particular, they make it possible to quickly identify areas where reactions are inefficient or where energy losses could occur, thus accelerating the optimization of these technologies.
A step towards sustainable storage of renewable energy
This work demonstrates that organic flow batteries have a real potential for clean energy storageparticularly for stationary applications linked to renewable energies. By making the measurement of kinetic properties more precise and faster, the new approach facilitates the design of more efficient and sustainable systems.
Although there is still a way to go before large-scale industrialization, this research constitutes a key step in optimizing storage technologies that are safer, less expensive and better suited to the challenges of the energy transition.
Source : CNRS
Legend of the illustration above: Principle of the spectroelectrochemical imaging method applied to organic flow batteries. Alternating current modulation, coupled with microfluidic imaging, makes it possible to connect AC absorbance to AC current and to map the electrochemical kinetics of the MV/4‑HO-TEMPO couple with a view to optimizing cell design.
© Chevalier et al.
