A new diagnostic tool for analyzing polymer-electrolyte (PEM) fuel-cell degradation has been developed by researchers at Lawrence Berkeley National Lab's Energy Conversion Group. The simple and fast tool, described in a paper published in January in the Journal of The Electrochemical Society, is based on analyzing changes in polarization curves of a cell over its lifetime.
The research found that the shape of the polarization-change curve and its sensitivity to oxygen concentration are unique for each degradation pathway based on analysis from a detailed 2-D numerical model of the cell. Using the polarization-change curve methodology, the primary mechanism for degradation (kinetic, ohmic, and/or transport related) could be identified. The technique was applied to two sets of data to explain performance changes after two different cells undergo voltage-cycling accelerated stress test, revealing that changes were kinetic and then ohmic or transport in nature depending on the cell type. The diagnostic tool provides a simple method for rapid determination of primary degradation mechanisms.