Effect of rheology controller agent addition to Micro-Porous Layers on PEMFC performances

Formulations of carbon-based inks for doctor blade applications were considered and the use of Carboxymethylcellulose (CMC) as rheology modifier and suspension stabilizer was proposed. Rheological measurement evidenced that CMC addition guarantees a good dispersion of the carbon powder which results in a higher stability of the ink. The electrical performances of Gas Diffusion Layer (GDL) coated with Micro-Porous Layers (MPLs) prepared with and without CMC were compared. A single PEMFC was used to assess the properties of these GDLs: electrochemical performances were tested in terms of I-V curves and of AC Electrochemical Impedance Spectroscopy (EIS) of the running cell. CMC-containing GDLs showed improved performances when the cell was operated at 80 °C and RH 80-60. Analysis of the EIS spectra demonstrated that, at high Current Density (CD), the CMC-based GDLs suffer for water management. Such a behavior was ascribed to a hydrophilic character of the GDL due to residual amounts of CMC in MPL coating. ISI P.73-77