First-Time Report of Operando X-Ray Computed Tomography Cell for 30 Bar Differential Pressure for Studying Components for Anion Exchange Membrane Water Electrolyzers

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In efforts to decarbonize many industrial sectors, water electrolysis technologies have been developed in recent years to produce high purity and high-pressure hydrogen gas with minimal carbon dioxide emissions. Hydrogen can be used for a vast number of applications such as energy storage, transportation, metallurgy, ammonia production, etc. making hydrogen technologies paramount to sustainability efforts. Existing technologies such as liquid alkaline water electrolysis (LAWE) and proton exchange membrane water electrolysis (PEMWE) have been vastly studied and have been introduced to markets; however, these technologies face low operational efficiencies (LAWE) or the use of expensive materials and catalysts (PEMWE). A newer research pathway towards alkaline exchange membrane water electrolysis (AEMWE) looks to combine the affordability of LAWE and the enhanced operational efficiencies such as differential pressure capabilities of PEMWE to bring forth a more affordable alternative to existing technologies. Integrated differential pressure operation can ultimately reduce required balance of plant costs by removing the expensive and high maintenance compressor requirements currently employed. To study the effects of differential operation, in this work operando x-ray computed tomography (CT) was used, for the first time, to visualize the channel intrusion of the membrane and porous transport layer when differential pressure (10-30 bar) was applied at the cathode. A land/channel cell design with electrolyte feed to the anode and an active area of 0.45 cm 2 was used with perfect sealing to enable this high-pressure operation. Balance of plant (BOP) components will be also discussed, especially for the cell of this small dimension that must be x-ray transparent. Simultaneously, polarization curves were obtained to evaluate electrochemical performance. Material properties (titanium vs nickel vs stainless steel) and morphological characteristics (thickness, particle shape, and porosity) effects on the observed deformation were studied. The use of the more flexible nickel and stainless steel as porous transport layers experienced increased deformation compared to the more rigid titanium material when using a 1 mm channel flow-field. Employment of thicker, denser porous transport layers were observed to decrease this deformation and enable differential pressure capabilities for this specific flow-field configuration. Figure 1

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