Effects of Deep Temperature Cycling on Nafion® 112 Membranes and Membrane Electrode Assemblies

A study was conducted to understand the physical and chemical changes in fuel cell membranes that result from Freeze/Thaw (F/T) cycling which might occur in electric vehicles. Nafion (R) membranes and membrane electrode assemblies (MEA) were subjected to 385 temperature cycles between +80 degrees C and -40 degrees C over a period of three months to examine the effects on key properties. These studies were done on both compressed and uncompressed materials in the un-humidified state. Although no catastrophic failures were seen, the analytical results shed some light on the relationship of temperature cycling to membrane structure, water management, ionic conductivity gas permeability and mechanical strength. Changes in water swelling behavior and dry densities were noted and the effect on ionic conductivity and cell performance was examined. The impact on catalyst activity and structural integrity of MEAs was evaluated electrochemically.