Fuel cell current degradation law and I-V performance prediction

The lifespan assessment of fuel cells is often too time-consuming for widespread implementation. Consequently, a reliable method for predicting their lifetime is essential to accurately evaluate their durability. Studying the ageing laws of fuel cells is crucial for lifetime prediction. In this study, the current degradation law is formulated based on the durability test results of 85 fuel cell samples. It demonstrates that the logarithm of fuel cell current decreases linearly over time under constant voltage conditions, and that the decay of the I-V curve follows the transverse compression law during the ageing process. This behavior is then explained as the degradation of the roughness factor (RF) and the dependence of the water and heat state on operating voltage. The causes of deviations from the decay law in certain cases are analysed. It's recommended to avoid the accumulation of water and nitrogen within the internal flow field of fuel cell during testing. Furthermore, a method for constructing the I-V curve is proposed, allowing the prediction of the I-V curve at any time during the stable decay period using the measured results of an I-V curve at a certain time and a working point at another. The determination coefficient for predicted I-V curves in two fuel cell cases exceeds 0.98. Lastly, an online lifetime prediction method is developed, enabling real-time estimation of both the remaining lifetime and the service lifetime based on a lifetime determination criterion during operation.