Investigation of the interplay between porous transport layer and flow field in AEMWE systems

Abstract

The need for green hydrogen production technologies that are compatible with the fluctuating energy production of renewable energy sources rises. Therefore, the interest in anion exchange membrane water electrolysis (AEMWE) as a lower-cost solution grows which results in an importance of improving the system performance. In this work, the interplay between the porous transport layer (PTL) and flow field (FF) of the AEMWE is investigated by performing two series of tests with a single electrolyte flow cell with an 1 M KOH electrolyte at 60 °C. In these tests only the components on the anode side are changed while the cathode stays the same. Each of the series is carried out with a different FF, once with Nickel (Ni) expanded mesh (EM) and once with Ni knitted mesh (KM). Furthermore, six different Ni-PTLs, varying in thickness and porosity, are tested for each FF. Two PTLs are have two layers with different porosities. In total, there are 12 different cell assemblies, each of which is pressure tested and electrochemically tested which includes polarization curve and electrochemical impedance spectroscopy (EIS). The results demonstrate that the KM as a FF leads to an decrease of high pressure peaks of approximately 50 % on average compared to the EM. This even pressure distribution is important for an effective performance due to an improved catalyst layer utilization which is demonstrated by the 16 % on average increase in current density for the KM compared to the EM. Moreover, this study shows that FF and PTL influence each other's performance, because a thickness change in the PTL can result in an increase or decrease of the performance depending in the FF.