On the Catalytic Degradation in Fuel Cell Power Supplies for Long-Life Mobile Field Sensors

Important tasks such as environment monitoring require field devices such as sensors that can operate for long durations. Current power supply technologies such as batteries limit many applications. Fuel cells are a promising alternative to batteries because they can have much higher energy densities. However, their lives may be short due to catalyst degradation. Here, a simplified model of proton exchange membrane (PEM) fuel cell catalyst degradation is applied to small fuel cells. The model focuses on the combined effects of catalyst dissolution and migration. The effect of migration on catalyst degradation is found to be substantial and this has not been accounted for in previous models. The model considers the effect of field conditions such as varying power demands, temperature and humidity, and predicts the catalyst life of the fuel cell and its power output. The predicted life is a proposed metric that can quantify the relative importance and effect of field conditions on the catalyst particularly for the design and control of fuel cell power supplies. Experiments are presented that support the model. This model is applied to a study on field sensors and results suggests unless PEM fuel cells are isolated from damaging field conditions, they will have short lives.