The technical WP involved during the first year of AEMELIA were WP 2 (Sustainable anion exchange ionomer for membranes), WP 3 (Electrode Development and half cell testing). Some work on the stack design was carried out in the WP 4 (Cell and Stack Design) and lastly, preliminary results on the benchmarck of commercial membrane was studied in the WP 5 (Single cell and Stack testing).
Brief summary of the work performed within those WPs will be presented below and more detailed results are explained in the part B (D 1.4) of the reporting period.
WP2: Sustainable anion exchange ionomer for membrane
The activity carried out in the framework of WP2, during the first year of the project, consisted in the development of new architecture of anion exchange polymer based on polyaromatic backbone compatible with sustainable solvents formulated for electrodes and membranes. SYENSQO was involved in the development of hydrocarbon polymer backbone functionalized with quaternary ammonium functional groups. As a starting point, a membrane based on perfluorinated quaternary ammonium Aquivion polymer, was used an internal standard and was completely characterized by CNR. Hydrocarbon polymer was developed, and solubility tests were carried out. Data on the ion exchange process in FUMATECH (FAA3-50) membranes has been collected by CNR for MATGENIX. SYENSQO has collected data on the solubility of proton-exchange membranes for MATEGNIX and they have developed data analysis tools to visualize the datasets from CNR and SYENSQO.
CNR has gathered literature on anion-exchange membranes and shared it with MATGENIX. First Machine Laarning models have been trained on the two datasets and MATEGNIX has started to analyze the literature automatically using large language models. CNR has selected and characterized in terms of physico-chemical and electrochemical tests the benchmarks (Fumatech and PiperIon membranes). In addition, recast membranes, starting from commercial polymers, were developed and characterized by reaching hydroxide conductivity >100 mS.cm-1 at T> 60 °C. The setup process for the scalability up to 200 cm2 active area was reached. In addition, the introduction of commercial recombination catalysts (evaluation of different loadings and typology) in the membrane structure was carried out.
SYENSQO membrane (BEion) has shown high hydroxide conductivity at 50°C (236 mS/cm) but, it was prone to degrade with the increase of temperature. Despite this promising results, that membrane could be used in AEMELIA stack because of the presence of fluorine, subsequent development will consist in synthetizing hydrocarbon based membrane with equivalent characteristics.
WP3: Catalyst and electrode development, half-cell testing.
Within the WP 3 some progresses were made on the fabrication of ionomer-free electrodes.
TECNALIA has studied electrode preparation based on PVD coating of MoS2 for the cathode and electrodeposition of NiFeO on the anode. After experiencing issues with the less active 2H crystallographic structure of MoS2, they succeed to obtain the most active 1T structure by increasing the power of plasma durintg the deposition. They also improve the adhesion strengh of the electrodeposited NiFeO on stainless steal fibers, by more severe etching pre treatment of the stainless steel felt. SINTEF has investigated another route to reach same kinf of electrode (without ionomer) by chemical reduction of metallic salts onto either Nickel foam for the cathode or Titanium mesh for the Anode. They have shown very active electrode based on NiMo on the cathpde and NiFeB on the anode and apparently a thermal treatment above 350°C even increase the activity of the anode. Now with these developments, single cell testing are the next actions that will be performed in the coming months.
Beside this disruptive approach, a conservative approach was also pursued and CNRS/IC2MP has synthesized nanopowder cathode catalyst based on NiMoS that has shown 200 mV overvoltage at 10 mA/cm² in 0.1 M KOH. This promising results need to be improved to reach the target of less than 150 mV@10mA/cm². Also at CEA, NiFeO anode catalyst was synthesized from aerogel/xerogel route in order to better control the microporosity of the catalyst. But the first syntheses lead to large particle size with low electron conductivity due to not high enough thermal post treatment.
In the mean time, intense work was pursued by ICL to propose the world-first premier non PGM recombination catalyst and a method to assess the active layer of non noble metal catalyst. They have proposed Ni2P as active material for oxygen reduction reaction and hydrogen evolution reaction. But to fulfill all the requirement for RC catalyst it also has to be active for the hydrogen oxidation reaction and this aspect has not been tested yet. About the evaluation of the electrochemical active surface area, underpotential copper deposition was found to be a suitable method.
WP4: Cell and Stack Design
During the first year of AEMELIA project, computational fluid dynamic calculations were carried out by SINTEF in order to investigate the influence of the stack design and the manifolds position to the pressure drop and the thermal management. The final objective being to maintain less than 3°C between the hottest and the coldest point. Based on these calculations some propositions of designs were proposed to CLAIND for manufacturing.
WP5: Single cell and stack testing
The work in this WP5 starts in the second year of the project.
Nevertheless, some preliminary work has been started by CNR-ITAE with the testing of single AEMEL cells including commercial catalysts and membranes. Fruitful insights were found, as example the performance of with PiperIon membrane at 70°C was equivalent to Fumatech membrane but at 90°C. While at 90°C the efficiency the cell with the PiperIon membrane drops from 70% to 67% at 1.2 A/cm². This result shows that it is possible to maintain high hydroxide conductivity with the fumatech membrane.
