In-Line Quality Control of Proton Exchange Membranes for Fuel Cells

Fuel cells have been in development since the 1960s and stand on the cusp of commercialization for large-scale applications such as non-polluting vehicles. However, they are held back by high manufacturing costs and expensive catalysts. The membrane alone accounts for as much as 45% of the total cost of a commercial fuel cell system. Moreover, manufacturing defects in the membrane lead to scrapped materials and cause cell failures that can cascade into complete stack failure, requiring additional time reworking the stack. Mainstream Engineering is developing an optical sensor system that uses cross-polarized light, providing significant benefits in increased resolution, improved accuracy, and increased detection speeds for the examination of fuel cell membranes and other films. The inspection technique samples every location on the roll stock such that defects (e.g., pinholes, scratches, bubbles) in membrane electrode assembly materials can be removed prior to assembly into fuel cell stacks and end-use devices, such as vehicles. Two different measurement principles for thickness determination using the same hardware are under evaluation. A prototype system was designed and integrated into a 14-inch-wide demonstration web line and was tested running autonomously in real time with PFSA membrane at line speeds up to 100 ft/min. A variety of other fuel cell membranes were also tested in other static or small-scale test configurations. Optical sensor development and pilot testing as part of a manufacturing quality control strategy will be presented.