Developing catalysts for cost-effective hydrogen synthesis to aid mass manufacture

The energy transition requires a lot of hydrogen. A German-New Zealand research collaboration is improving AEM electrolysis for green hydrogen production in the HighHy project.

The Dresden-based Fraunhofer-IFAM scientists are using manganese and nickel, which are abundant and resource-efficient, to commercialize the promising electrolysis technique. The new technology has other benefits than cheaper costs.

Hydrogen may solve numerous energy transition issues: road traffic, industry, and heat supply use the lightest element in the periodic table. Hydrogen will be needed in significant quantities in the future because of its versatility. The HighHy project team wants to create catalysts for efficient, cost-effective hydrogen synthesis to help mass production.

Electrolysis splits water molecules in water with a conducting salt, the electrolyte, into hydrogen and oxygen. Hydrogen bonds store energy. So, the gas is an appealing choice for long-term storage of wind and solar energy that cannot be put directly into the grid. Regenerative energy sources produce “green” hydrogen.

Three electrolysis techniques are widely used. Alkaline electrolysis (AEL)—adding potassium hydroxide to water—is the most common and technically relevant. The low lower partial load range limits the bandwidth’s electrical load while using a fluctuating power supply. Hydrogen ions move in a strongly acidic environment through a gas-tight membrane electrode assembly (MEA) in a proton exchange membrane (PEM-EL) electrolyzer.

Anion exchange membrane electrolysis is novel (anion exchange membranes, AEM). It combines the AEL’s long-term stability and use of cheap metals with the PEM-performance, EL’s adaptability to diverse loads, and gas purity. The oxygen evolution reaction (OER) in AEM electrolysis is too slow for industrial use when non-precious metals are utilized. Hence, water electrolysis requires a high cell voltage to achieve the requisite current densities, making hydrogen synthesis energy-intensive.

HighHy solves this issue: The Federal Ministry of Education and Research (BMBF) funds German-New Zealand cooperation to develop OER catalysts and highly efficient AEM electrolysers.

The HighHy project wants to use a novel nickel-manganese compound as an OER catalyst to produce green hydrogen industrially utilizing AEM electrolysis. Mixing has major benefits: Both metals are cheap and abundant. They also show promise chemically. The HighHy institutions are working on methods to create a perfect industrial link.

Powder metallurgy techniques from Fraunhofer IFAM help develop the catalyst: The catalyst’s electrochemical activity, electrode contacting, electrolyte flow, and gas bubble discharge must be optimized. Knowledge of porous structures, such those created by nickel-manganese powder coating, is crucial. Researchers anticipate the new catalysts will minimize the electrical energy needed to produce oxygen and boost AEM electrolysis efficiency.

The EU targets 48 kilowatt hours per kilogram of hydrogen produced by 2030 for industrially usable AEM electrolysis. Hence, the AEM-EL might attain 80 percent efficiency, equivalent to the AEL and PEM-EL processes, with greater flexibility in loads driven and locations of application and reduced material costs. AEM electrolysis systems cost 300 euros per installed kilowatt hour, while PEM-ELs cost 500 euros. Classic alkaline electrolysis has a 400-euro goal.

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