A Study of the Spatial Distribution Characteristics of Water in Proton Exchange Membrane Fuel Cells: The Effect of Microporous Layers

Proton exchange membrane fuel cell (PEMFC) is a direct hydrogen utilization device, and its application in transportation is an important scenario for hydrogen energy consumption. Within the fuel cell, the pore structure of the microporous layer (MPL) affects the transport of reactive gases and the transport of generated water, and has an important role in the water management of fuel cell. In this study, the performance of fuel cells with/without MPLs was systematically tested within a wide range of humidity conditions. The experimental results showed that the exhaust gas dew point temperature of the cell with the microporous layer (named as wMPL cell) at 30% RH was consistently about 10 ℃ lower than that of the cell without the microporous layer (named as woMPL cell). The current distribution indicated that the presence of the MPL reduced the outward diffusion of water from the catalyst layer to flow field, which improved the hydration condition of PEM. Under high humidity, the exhaust gas of the wMPL cell was on average 15 ℃ higher than that of the woMPL cell, indicating that the MPLs alleviated the flooding condition in the fuel cells by increasing drainage. MPL helped improve the current distribution in the exit region, and reduced the mass transfer impedance. This finding was of great significance for optimizing the design of fuel cell components, improving the operational efficiency, and promoting the application of fuel cells and hydrogen energy.