Journal article Open Access
Bezmalinović, Dario; Barbir, Frano
Polarization change curves, defined as a difference between the polarization curve at the beginning of life and the actual polarization curve after the cell has been operational for some time, were used to analyze degradation of a PEM fuel cell stacks. Such an analysis identified and quantified different losses due to degradation, i.e., it assessed the fuel cell state of health. In order to verify that this state of health assessment method indeed identifies the real causes of fuel cell degradation, it was applied to a controlled experiment involving a single cell with known or previously independently determined degradation mechanism(s) by being exposed to an accelerated stress test for electrocatalyst degradation. Degradation, i.e., loss of voltage was due to increase of activation losses and increase of resistance in the catalyst layer, both most likely due to the loss of catalyst electrochemically active area. The results of the polarization change curves analysis correspond to the findings of the periodic individual tests performed during the accelerated stress test, such as electrochemical impedance spectroscopy, cyclic voltammetry and linear sweep voltammetry. Therefore, this method has potential to be used as a relatively quick and simple, yet effective, state of health assessment tool.