PEM Electrolyzer Characterization and Limitations When Using Carbon-Based Hardware and Material Sets

Abstract

In contradiction to the more established research field of proton exchange membrane fuel cells (PEMFCs), the research and development field for proton exchange membrane water electrolysis (PEMWE) is an upcoming and growing area. Over the past decades, a specific fuel cell research hardware configuration has been widely accepted for material development work that requires typical performance and durability tests on subscale cells. This hardware consists of thick endplates often made of aluminum, gold plated copper current collectors that are insulated with a sheet material from the endplate and graphite flow-fields that contain the flow channel structure. The latter may be machined in many designs ranging from single to multiple serpentine or parallel flow patterns. In contrast to the fuel cell field, the electrolysis research field does not yet have established material sets. Operating conditions are harsher than in a fuel cell system, since the potentials required for the oxygen evolution reaction are significantly higher. In commercial water electrolysis systems this is compensated by typically using titanium material sets that are often protected against oxidation through coating processes. Such material choices make small scale research hardware and porous transport layers expensive and very difficult to source. In this work, we show that the stability of traditional carbon-based fuel cell materials is sufficient for electrolyzer initial performance characterization procedures such as cell conditioning, a limited number of polarization curve measurements, and electrochemical impedance spectroscopy. We identify and quantify the onset of carbon degradation and define a strategy that allows the utilization of standard fuel cell hardware for specific PEMWE experiments. With knowledge that existing fuel cell materials can be applied in electrolyzer research by acknowledging the associated limitations, fuel cell research hardware and experience can be more readily transferred to the younger and rapidly growing electrolyzer research field.