De-Risking PEM-Electrolysis: Advanced Characterization for the Pathway Towards the GW-Scale

“Green” hydrogen, from carbon-neutral energy sources such as wind or solar energy, will play a key role in the decarbonization of the electrical grid and a vast number of industrial sectors 1 . To produce the large quantities of hydrogen that are needed to achieve this, Proton exchange membrane electrolytic cells (PEMEC) are one of the most promising technologies available right now. However, especially in long-term and dynamic operation, PEMEC can still be subject to various degradation phenomena, which is detrimental to their economic feasibility as a hydrogen source 2,3 . For an accelerated market ramp-up of PEMEC, a comprehensive de-risking of the technology is essential. Here, we present several of our efforts to accelerate the upscaling of PEMEC technology towards the GW scale for a “green” hydrogen economy. A central aspect for this is the investigation of degradation patterns in PEMEC from a laboratory scale level up to industrial scale PEM electrolyzers on a component, cell, and stack level. A degradation in the electrochemical performance of the PEMEC is determined by the observation of changes in the polarization curves and the electrochemical impedance spectroscopy (EIS) response after long-term cycling of the cells or stacks up to an industrially relevant scale. This is further refined by a variety of sensors in the test benches, e.g. for measuring the gas permeation through the membrane electrode assembly (MEA) among many others. This allows us to make generalized statements on the “State-of-health” of the PEMEC. To make even more in-depth statements on possible degradation phenomena, a variety of complementary analytical methods are used post-mortem on the MEA to elucidate on possible origins of the reduced performance. X-ray computed tomography (XCT) is used to determine morphological changes such as cracks, voids or foreign particles in both electrodes and the membrane of the MEA with micron resolution. Selectively performed cross-section analysis with focused ion beam (FIB) in combination with scanning/transmission electron microscopy (SEM/TEM) can provide more information on the possible origin of irregularities. More detailed studies of the electrode morphology and conductivity is obtained by general conductivity measurements under controlled humidity/temperature conditions on a macroscale, and by atomic force microscopy (AFM) on a micro- and nanoscale. To probe the properties of the PFSA membrane in different states, nuclear magnetic resonance spectroscopy (NMR) is used. To ascertain the quality of the MEA in the production line even before the use in a PEMEC, a Raman spectroscopy approach was used as an in-line compatible method. With the results of this comprehensive testing- and characterization approach and formulating novel approaches for online analytics in PEMEC manufacturing, we want to contribute the de-risking of PEM electrolysis for an acceleration of the technology implementation towards a GW-scale. This highlights the importance of fundamental spectroscopic and microscopic methods even for large industrial scale devices to improve PEMEC and achieve a more widespread adoption of the technology. Acknowledgment: Financial support was provided by the German Federal Ministry of Education and Research (BMBF) within the H 2 Giga project DERIEL (grant number 03HY122C) and SEGIWA (grant number 03HY121) IEA. Global Hydrogen Review 2023 . Sayed-Ahmed, H., Toldy, I. & Santasalo-Aarnio, A. Dynamic operation of proton exchange membrane electrolyzers—Critical review. Renew. Sustain. Energy Rev. 189 , 113883 (2024). Siracusano, S. et al. Degradation issues of PEM electrolysis MEAs. Renew. Energy 123 , 52–57 (2018).