(i) Optimisation and utilisation of advanced AEM and ionomers:
Different generations of AEM and ionomers were developed. The polymer optimization focused on the optimization and scale-up of the synthetical process to meet the requirements of large-area membrane and ionomer preparation. The main task was to improve batch-to-batch consistency while keeping the high quality regarding the desired KPIs. Improved synthesis process control enabled the production of polymers with high batch-to-batch reproducibility and increased yield. High-quality anion-conductive materials were delivered to prepare MEAs for the stack. To determine the KPIs, several AEM characterization methods were developed or adapted.
(ii) Development of cost-efficient and stable catalyst for high-performance electrodes:
CHANNEL developed low-cost non-PGM catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) using scalable synthesis methods. The electrocatalysts were synthesised by combining materials such as nickel, iron, and molybdenum in optimal composition and structure to exhibit comparable performance and stability to the precious metals, demonstrating that switching to non-precious metal electrodes is a promising route for AEMEL.
Ni-based HER catalyst achieved <100 mV overpotential at -10 mA/cm2 in 0.5M KOH with excellent batch-to-batch reproducibility, besides showing outstanding stability over 1000h. On the other hand, the Ni-based OER catalyst showed <300 mV overpotential at 10 mA/cm2 with an excellent stability for more than 500h.
Ink formulations and dispersing methods with anion conductive ionomers and non-PGM HER and OER catalysts were developed and optimized. The catalyst loading and ionomer content were optimized for both electrodes. The optimized membrane and electrodes allowed to reach the single-cell performance target of 1 A/cm2 at 1.85 V. A long-term test of more than 1000h showed good stability of all components. A computational model of an AEMEL was developed, which was used to simulate the cell performance and lifetime under varying operational scenarios. The model achieved a reasonably good fit to the experimental data, particularly within the large Ohmic region above about 0.5 A/cm2.
iii) Development of system models to help guide the stack design and integration of components into the stack and, design of BoP:
Guided by modelling work CHANNEL designed a prototype 2kW stack consisting of 16 cells with an active area of 64 cm2. The design is flexible to use some different approaches for the flow fields, sealings, electrodes and MEAs. The BoP for the final testing was also designed and optimized, including a visual interface to facilitate monitoring and data acquisition with high accuracy.
Despite most of the components have reached the targets, as evidenced in single-cell testing, in terms of the stack the situation was more complicated. Stack performance was about 600 mV above the targeted voltage at 1 A/cm2. Nevertheless, the stack prototype was validated over 260 h at atmospheric pressure due to high H2-crossover at 30 bar differential pressure and low current density (voltage limitation) resulting in a degradation rate of 38 µV/h.
(iv) Market analysis, cost, and performance assessment from experimental results based on the CHANNEL 2 kW stack prototype:
The analysis market showed a good perspective for this new technology, with a wide range of possible implementations such as zero-emission transport, both public and private including refuelling stations, chemicals productions, domestic, and energy storage applications. These characteristics, together with a 100% EU supply chain, can increase EU competitiveness in the production of green hydrogen from renewable energy sources.
Even if the cost associated to the 2kW stack prototype is high, costs analysis showed that the CAPEX below 600 €/kW at a 500kW scale system is achievable with CHANNEL technology. The main exploitable results are the demonstration of cost-effectiveness and the business opportunities for CHANNEL's stack, together with the achievement of a 100% EU supply chain. The results are being exploited scientifically by presentations on 10 conferences, publications in 4 peer-reviewed journals, and one UK patent application of the novel HER catalysts. The scientific CHANNEL findings contributed to a better understanding of AEMEL. The results will be further used by the project partners for follow-up research and development projects.
