Veco, Fraunhofer IFAM, and Fraunhofer IWS Dresden collaboratively developed and tested long-term stable substrates and Raney Ni-based catalysts for hydrogen and oxygen evolution in high-temperature, pressurized electrolysis. Specifically, they have focused on achieving stability in 120°C, 40 wt.% KOH. Fraunhofer IFAM designed a new test infrastructure to accommodate these extreme conditions, as durability data for materials and sensors under such conditions is limited.
Significant findings emerged from the uniform testing of Ni-based catalyst layers on Ni substrates by Veco. These tests provided insights into the behaviour of the layers concerning temperature, coating thickness, and substrate form factors.
Fraunhofer IFAM’s 3EA test infrastructure in Dresden was also adapted to measure at temperatures above 100°C, preventing electrolyte contamination from Si or Fe. A slight degradation was observed, which can be attributed to the highly concentrated KOH solution (40 wt%). Even at 80°C, the higher concentration has a negative impact. It is worth to mention that the catalyst system can be used as a bifunctional system (HER and OER). Additionally, AGFA separators were successfully coated using atmospheric plasma spraying (APS), to improve durability under high-temperature, high-pressure electrolysis.
The current separators used in state-of-the-art alkaline electrolyzers are not designed for increased temperature and pressure. The optimization strategies focused on pore structure, hydrophilicity enhancement and the thermal stability. Through collaborative work between AGFA and Syensqo, polymers of different families with enhanced stability have being screened for the required temperature and KOH concentration with conclusive results still pending. In paralell, Zirfon membrane is also being optimized, with a method developed to reduce gas crossover caused by higher pressure.
FHA’s pilot-scale test bench is nearly upgraded, with component and control logic selected to meet high-pressure, high-temperature demands.
