Sustainable Anion Exchange Membrane Electrolyser for large-scale green hydrogen production

The French national strategy on decarbonized hydrogen aims to install 6.5 GW of electrolyser capacity in France by the year 2030, to develop an industrial sector around hydrogen and to sustain the innovation and research in this sector. For this last reason the French programme PEPR-H2 was created and is operated by the French National Research Agency (ANR). DAEMONHYC is a project lead by the LEMTA and financed by the PEPR-H2 programme that aims to develop new materials and to increase the performance and durability of Anion Exchange Membrane Water Electrolysers (AEMWE). AEMWE is an emerging technology thanks to the recent advancements in anion exchange membranes that enables the construction of durable zero-gap configuration electrolysers in alkaline environments. This is an improvement over the traditional alkaline water electrolysers (AWE) that have low hydrogen production yields due to the gap between electrodes that brings high internal resistances and therefore lower performances. In this way, AEMWE is similar to the now proven technology of proton exchange membrane water electrolysers (PEMWE), but with the added benefit of not depending on rare and expensive PGM electrocatalysts like Iridium. In fact, Iridium production is so low, reaching only 7 tons annually, that it is considered a potential bottleneck in the deployment of PEMWEs in large scale, and is one reason behind the interest in alternative electrolysis technologies, like AEMWE and SOEC (Solid Oxide Electrolysis Cell). This master thesis is a firsthand experience into assembling and operating a functional AEMWE cell for the first time at LEMTA, and it aims to provide invaluable guideline for future research in the subject. Two AEMWE cells were assembled using both PGM and non-PGM materials and commercial anion exchange membranes available in the market, and a reference electrode was installed in each cell following the methodology employed at the laboratory. 1 M KOH supporting electrolyte solution was used to supply both water and electrolyte to the cell, and two electrolyte feeding configurations were tested. Polarization curves were obtained for the different configurations and cells at different temperatures—to test the performance of the cells and to obtain electrochemical data for posterior analysis. Finally, a simple electrochemical model was employed to process the data, and the calculated electrochemical parameters are reported. The results demonstrate how electrolyser performance benefits from higher temperatures, and how anhydrous cathode operation can be advantageous when operating AEMWEs. They also demonstrate the feasibility of operating a PGM-free electrolyser and the gap that still exists in electrocatalyst performance compared to a PGM cell, especially respect to platinum as cathode electrocatalyst for the HER reaction. It is also demonstrated that Iridium is not an outstanding electrocatalyst for the OER reaction in alkaline media. These results are in line with the scientific literature reviewed.