Latorrata S., Gallo Stampino P., Cristiani C., Dotelli G., 2014, Novel Superhydrophobic Gas Diffusion Media for PEM Fuel Cells: Evaluation of Performance and Durability, Chemical Engineering Transactions, 41, 241-246.
Micro-porous layer (MPL) is a crucial component for an efficient water management in Polymer Electrolyte Membrane Fuel Cells (PEMFCs). Nowadays, MPLs are obtained by depositing a dispersion, commonly known as ink, containing carbon black particles and PTFE onto a carbon cloth substrate. In this work PTFE was replaced by an innovative fluorinated polymer in order to improve hydrophobic properties of MPLs and consequently the water management of the whole system. Moreover, carbon nanotubes (CNTs) partially substituted carbon black in ink formulation. The new polymer allowed to decrease considerably the treatment temperature (260 °C) with respect to the one necessary with conventional samples based on PTFE (350 °C). Fuel cells assembled with the sample containing CNTs showed better performances than those obtained with traditional CNTs-free MPLs. Durability of the most performant sample was assessed. Ad-hoc Accelerated Stress Tests (ASTs) were developed; they showed that the main degradation for MPL is due to mechanical stresses, caused by reactants and water flow, which leads to detachment of materials and to a consequent dramatic mass transfer resistance increase.
