Micro-perforation of the diffusion media for polymer electrolyte membrane fuel cells using short and ultrashort laser pulses

The water management within polymer electrolyte membrane fuel cells is one of the main challenges limiting their extensive commercial application. By introducing directed pores in the carbon-based diffusion media, the water transport properties can be improved. Thus, the performance at demanding operating conditions and the lifetime of the fuel cell can be enhanced. In this work, the microporous layer of a diffusion media was perforated by locally ablating material using short and ultrashort-pulsed laser radiation with infrared wavelength. The influence of the pulse duration as well as the peak pulse fluence and the number of pulses on the ablation rate and the surface quality was evaluated. Laser scanning microscopy was applied to assess the topography of the micro-drillings. The heat-affected zone around the micro-drillings was investigated by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The impact of short and ultrashort pulse laser radiation on the hydrophobic binder within the microporous layer was studied. Results showed a decreased binder evaporation in the vicinity of the micro-drillings by a reduction of the pulse length from the nanosecond to the picosecond range.