Novel electrode materials for high performing aqueous organic redox flow batteries.
The aim of this 2-year fellowship is to develop novel and robust electrodes to improve the performance of Aqueous Organic Redox Flow Batteries (AORFBs) for renewable energy storage applications. The research will be carried out at Kemiwatt (Rennes, France), who have been developing AORFBs since 2014, in collaboration with the Institut des Sciences Chimiques de Rennes (ISCR), University of Rennes 1 (France) as secondment. Carbon felts, which are the most commonly used electrodes for AORFBs, will be modified in order to enhance the interactions between the electrode and the electrolytes to further improve the performance of the batteries. Two routes of modifications will be explored: i) pulse-electrodeposition of metals on carbon felt electrodes using a flow-through system and ii) electrografting of organic modifiers via the aryl diazonium salts method.  By optimising the properties of the electrodes in terms of specific surface area, wettability, local pH and charge transfer, positive impacts on the power and energy densities and efficiencies of the battery are expected. Therefore, the objectives are threefold: i) to develop novel carbon felt electrodes modified by electrodeposition and electrografting, ii) to study the performance and durability of the modified electrodes for AORFBs application, via the optimisation of the electrode/electrolyte interactions, iii) to upscale (from 25 cm² up to 2100 cm²) the electrode surface modification process and to implement and test the corresponding electrodes in pilot-scale reactors. By developing novel modified carbon felts, this fellowship aims at improving the performance and stability of AORFBs. This will help Kemiwatt pursue their technological development and achieve their goals by 2023. It will in turn provide valuable insight to the scientific community on an aspect that is currently being overlooked and that could yet significant help improve the technology and the EU to reach its decarbonisation targets by 2050.