Insights into the Stability and Formation of Water Droplets Using Operando X-Ray Tomographic Microscopy

Abstract

Efficient removal of the electrochemically produced water from the gas diffusion layer (GDL) in polymer electrolyte fuel cells (PEFC) is crucial for reducing the mass transport losses and enabling the technology to become a viable energy solution. Understanding the interaction between the water cluster percolation through the GDL and the droplet formation and detachment in the gas channel could enable the design of advanced GDL materials, which provide optimal water management. In this study, a catalyst-coated membrane (CCM) with 8 small, independent active areas (0.0625 mm2 each) is investigated using operando X-ray tomographic microscopy (XTM) to study the transient development and interaction of multiple percolating water clusters in a GDL and droplet formation and detachment in the channel. The results of the study provide insights into the water removal in PEFC through the development of percolating networks in the GDL. Transient instabilities in the developed percolating water networks associated with break-through and droplet detachment were also observed.