Cross-polarized Near-UV/Vis Detector for In-line Quality Control of PEM Materials

Modern fuel cells have been in development since the 1960s and stand on the cusp of commercialization, but are held back by high manufacturing costs and expensive catalysts. Membrane costs alone can account for as much as 45% of the total cost of a commercial fuel cell system. Furthermore, manufacturing defects in the membrane can cascade into complete stack failure, which is expensive and time consuming to resolve. These defects are often not discovered until costly catalyst has been irreversibly applied and the MEA is fully assembled, leading to additional wasted materials and a slow correction of the coating process. To achieve large scale commercialization, fuel cell manufacturing needs a high-efficiency, real-time quality control system that can provide 100% inspection of the membrane at coating speeds up to 60 ft/min. Mainstream’s approach uses near-UV/Vis light to infer membrane film thickness, composition, and defects with a single detector, light source, and pair of cross-polarizers. Mainstream’s Cross-Polarized Near-UV/Vis (CPNUVV) system, which we call the Mantis Eye, simultaneously measures membrane thickness and determines and quantifies membrane defects in real-time at roll-to-roll coating speeds. This information can be relayed to a printer to mark defective membranes, allowing exclusion from catalyst coating as well as rapid feedback to correct the membrane coating process. During Phase IIB, Mainstream developed the Mantis Eye low-cost optical detector for continuous analysis of PEM fuel cell materials. The inspection technique samples the entire web in real-time so defects in MEA materials can be removed prior to assembly into fuel cell stacks and automotive systems. In the sequential Phase IIC program, Mainstream will conduct long term testing of a production-intent unit at a manufacturer’s facilities to fully validate and commercialize the Mantis Eye technology developed in Phase IIB. The Mantis Eye Scanner will help drive down costs and increase reliability of fuel cell membranes which are often still too expensive to compete with conventional power technologies. The early detection of defective membranes allows their removal before further coating or assembly steps, reducing costs by minimizing wasteful use of expensive platinum catalyst, labor used to construct stack materials, and defective returns from the customer. The Mantis Eye Scanner is not limited to fuel cell membranes and other membrane processes can benefit from improved quality control devices.