Current Density Distribution of Electrolyzer Flow Fields: In Situ Current Mapping and Neutron Radiography

A polymer electrolyte membrane water electrolyzer plays an important role in the development of renewable energy storage systems due to its high current density capability and quick response to intermittent input power variations. Mass transport limitation and temperature hot-spot formation within this type of electrolyzer cell will, however, lead to membrane degradation and lower efficiency. Robustness is highly dependent on the flow field (FF) design used because the FFs at the anode side serve the purpose of carrying the water, which acts as both a coolant and a reactant. In this study, two electrolyzer FF designs, both with an active area of 25 cm2, were fabricated in house at HySA Infrastructure (South Africa). Thereafter, they were characterized in terms of current density distribution and temperature distribution, using a segmented sensor plate (S++ Simulation Services, Germany) and quasidynamic neutron radiography. The water and gas content at both the anode and cathode sides were quantified at the Neutron Imaging Facility of the Center for Neutron Research, National Institute of Standards and Technology. It was found that a PIN-type FF design has a more homogeneous current and temperature density distribution across the surface of the FF than the parallel FF design.