Aqueous electrolysers have to innovate in their architecture

The chemical industry is a major CO₂ emitter. As our societies must cope with the consequences of climate change, it is more important than ever to strongly decarbonize this industry. Hydrogen is a reagent commonly used to synthetize various products (fertilizers, steel or methanol). Unfortunately, more than 95% of the hydrogen is produced by steam reforming of hydrocarbons, a cheap process that emits a lot of CO2. One solution to reduce the carbon footprint of the hydrogen production would be to produce it at larger scale thanks to aqueous electrolysers powered by renewable energies, thus creating “green” hydrogen.

Despite the researches already carried out, the breakthroughs made in laboratories, especially at the material level, are struggling to materialize at the industrial level. Although the electrolyser technology is older than the battery one, it did not known the same success story. This is due to the very nature of the electrolysers which are complex open systems where the influence of materials developed in laboratories on the overall performances is hardly estimable.

By keeping the systems as they are designed today, the main gain in cost could be achieved changing the production scale and developing large-scale electrolysers. While the price of catalyzers used represents a small part of the total value of an electrolyser, the quantity of rare materials, such as the iridium, to equip the entire chemical industry will certainly be the limiting parameter. Thus, the performances and the durability of these materials must be improved in order to minimize the needed quantity by system. Nonetheless, researchers and industrials assess the performances of these materials and systems differently. The gap between academic and industrial characterization comes from the complexity of the analyzed systems.

Aware of the intrinsic limits of these systems, two researchers from the CSE laboratory in Collège de France propose in an article published in Nature Materaisl to overcome these problems by modifying in depth the architecture of the electrolysers through the integration of design concepts inspired by the field of batteries. They propose an overview of the work already done and promising on the subject. Two design options emerge: To develop electrolyser without separator membrane or to decorrelate the energy storge and hydrogen production functions in these systems.

All the conclusions can be found in the Perspective available at the following link: https://www.nature.com/articles/s41563-020-0788-3