Enabling High Power Density Fuel Cells by Evaporative Cooling with Advanced Porous Media

Despite being a promising technology for automotive applications, polymer electrolyte fuel cells still face challenges to reduce their complexity and cost. One challenge is to achieve good humidification, which is essential for a fuel cell membrane, without expensive external humidifiers. Here we present an evaporative cooling concept that manages humidification and cooling simultaneously, and does not require any additional layer to the structure of the cell. To this aim, water flows in the fuel cell itself through a small number of the flowfields' channels. Modified gas diffusion layers, with separate parallel hydrophilic regions, are capable of wicking the water from these supply channels and bring it in contact to the gas flow to evaporate, thus providing cooling and humidification. Our results show that this concept can provide the necessary cooling power and humidification for a cell with completely dry inlet gases at 80 °C, and has the potential for working at higher temperatures.