In-Line Quality Control with Terahertz Scanners for High-throughput Production of Low Temperature Fuel Cells and Electrolyzer MEAs

Lookin, Inc., in collaboration with National Renewable Energy Laboratory (NREL), proposes to develop a transformative quality control (QC) instrument, a high-throughput terahertz scanner, for in-line QC of fuel cell and electrolyzer membrane electrode assemblies (MEAs) at different stages of roll-to-roll (R2R) manufacturing. Hydrogen and fuel cell technologies provide clean, portable, high-density energy, which is useful in many settings including medium- and heavy-duty proton exchange membrane (PEM) fuel cell vehicles and for operation in remote locations. As fuel cell manufacturing is a complex and precise process, it requires strict quality control to ensure the performance and safety of the final product. Therefore, an in-line quality control instrument becomes a very valuable tool that can help manufacturers achieve these goals. Such an instrument can assure high-quality products by continuously monitoring critical parameters during production, help with process optimization by identifying inefficiencies during manufacturing, and offer cost reduction by decreasing the scrap rate. Many available techniques can be used to characterize the substructure of fuel cells and electrolyzer MEAs, such as thermography, optical reflectance imaging, or X-ray imaging. However, these techniques are limited in their field-of-view and/or throughput. To address the limitations of the existing QC techniques, Lookin proposes a scanner that employs terahertz radiation. Terahertz waves offer unique functionalities for QC applications. They can penetrate through many coatings that are nontransparent to visible light and provide 3D images of structures. Unlike X-rays, they are non-ionizing and non-destructive. Despite these great promises, the low sensitivity and scanning speed of existing terahertz scanners have limited their usage in many practical applications. Lookinĺs breakthrough terahertz scanner technology addresses the limitations of existing terahertz scanners by providing 1000-times higher sensitivity and scanning speed compared to the state-of-the-art, through a patented terahertz transceiver technology developed by Lookinĺs founders. During the Phase I program, our team developed a laboratory prototype of the terahertz scanner and demonstrated the feasibility of the technology in the laboratory for defect and nonuniformity detection of fuel cell and electrolyzer MEA structures. We characterized PEMs, catalyst-coated membranes (CCMs), gas-diffusion electrodes (GDEs), gas-diffusion layers (GDLs), and fuel cell/electrolyzer MEAs, showed terahertz scanning is an effective method in finding thickness variation and surface defects on PEMs, determining Pt loading of CCMs and GDEs, finding surface defects, voids, agglomerates, cracks on GDEs and scratches and agglomerates on GDLs. Encouraged by the results of the Phase I program, our team wants to develop a field prototype of the terahertz scanner in the Phase II program and install it to R2R machine at the fuel cell manufacturing line of our subcontractor group at NREL to optimize all aspects of the terahertz scanner and demonstrate its value on rolls of MEA specimens in a high-throughput process. During these measurements, we will also improve our data analysis algorithm by implementing machine learning techniques to improve sensitivity and accuracy. By enabling high-throughput and high-accuracy detection of defects in fuel cell and electrolyzer MEAs at early stages of manufacturing, our proposed instrument would be an indispensable tool for manufacturers.