Electrochemical Evaluation of Constant Voltage Activation Strategies for PEM Fuel Cells: Advantages of Low‐Voltage Break‐In

Proton exchange membrane (PEM) fuel cells are a promising alternative to combustion engines due to their high efficiency and low greenhouse gas emissions. However, the mass production of fuel cells is costly. One reason for the high production costs is the time and hydrogen‐consuming break‐in (activation). Developing a fast and gentle break‐in procedure requires understanding the physical and electrochemical mechanisms triggered by different break‐in methods. This study represents the first step in this direction, revealing the physical and electrochemical processes triggered by three different voltage levels: 0.2, 0.6, and 0.9 V. Polarization curves and electrochemical impedance spectroscopy (EIS) measurements were employed to elucidate the physical and electrochemical processes associated with the break‐in at various voltage levels. The most promising results were obtained at 0.2 V. The detected performance increase was 9.0% ± 1.8% at 1 A cm −2 current density compared to a performance increase of 6.2% ± 1.2% at 0.6 V. In addition, the constant voltage break‐in at 0.2 V was observed to achieve comparable performance improvements to a standard voltage cycling break‐in. Membrane hydration and washing out impurities are the most relevant processes leading to the highest performance improvement at the low voltage level. While relative humidity (RH) impacts the results, no impact has been observed by intermediate characterization steps. Understanding the advantages of a low voltage level helps to develop an optimal break‐in, which saves time and hydrogen, and paves the way for accelerated industrialization of PEM fuel cells.