Simultaneous in situ measurements and numerical analysis of mass transfer in polymer electrolyte fuel cell electrode slurries during drying

Herein, novel simultaneous in situ measurements of electrode slurries used to fabricate polymer electrolyte fuel cell electrodes during the drying process were conducted and analyzed via numerical simulation to understand mass transfer during drying and structure formation mechanism of the electrodes. The structure of the porous electrodes that affects cell performance is formed during drying of the electrode slurries. However, directly observing the state of the opaque electrode slurries is difficult, and thus their drying behavior has not been well understood. This study focuses on the variation in coated film thickness and the variation of electrical resistance of the electrode slurries during drying due to solvent evaporation and solid-phase agglomeration. A novel measurement technique of the electrode slurries’ electrical resistance is developed using a microelectrodeterminal chip. Time-dependent variations of electrical resistance and film thickness during drying are simultaneously measured. The results are analyzed and compared with the numerical simulations results. Electrode material distribution in the slurry varied according to the type of carbon materials. The electrode slurry containing platinum-supported carbon particles as a catalyst formed a sedimentary layer and a surface accumulation layer of the particles. Such drying behavior affected the resultant porous structure in the form of