Development of thin solid polymer electrolytes for highly efficient electrolyzers

Advanced electrolyzers are a promising platform for the so-called Power to molecules approach, in which electric current is employed to transform molecules on demand. This transformation addresses two of the most pressing challenges facing humankind: green hydrogen production and electrochemical CO₂ conversion. To be successful, both in terms of performance and stability, future electrolyzer development must be done in consideration of the whole membrane-electrode-assembly (MEA), to ensure proper interplay between electrodes, reagents, and electrolyte. The membrane has a vital function of passing ions with as little resistance as possible, while preventing cross-over of products. For example, for green hydrogen electrolysis, the membrane needs to prevent the cross-over of hydrogen and oxygen. The concentration of hydrogen in the oxygen mix, and vice versa, cannot be more than a few percent at most because of safety considerations. This means that the membrane must be made thick enough to prevent the gas cross-over, while for a high efficiency the membrane should be as thin as possible for lowest ionic resistance. Hence, in practical systems, a trade-off needs to be made. Another issue is the chemical stability of the membrane, as extremely high pH values can be reached locally. For this reason, ceramic based diaphragms are used today for alkaline water electrolysis. The cationic chemical groups in anion exchange membranes (AEM) typically suffer from chemical degradation under extreme alkaline conditions. Hence, the development of dense gas tight and thin membranes with good chemical stability is desired. In another example, for CO₂ electroreduction, the chemical selectivity of the membrane also affects the electrocatalytic mechanism.

At imec, we are working on the miniaturization of the MEA with a few micrometers thin metal nanomesh as catalytic electrode. To complete, the thin MEA also thin membranes which can be conformally assembled with the nanostructured electrodes are needed. In this PhD topic, you will develop polymer membranes and its coating for fabrication of stable and miniaturized MEA.  The PhD topic is a collaboration between the group of prof.  Ivo Vankelecom (cMACS, KU-Leuven) which is an expert in membrane development, and prof. Philippe Vereecken (cMACS, KU-Leuven and imec) who is an expert in electrochemistry and nanostructured materials.