Determination of Oxygen and Hydrogen Mass Transfer Coefficients in PEMFC GDE and Their Separation into Gas and Electrolyte Contributions
Abstract
The purpose of the project was development and validation of a novel methodology on determination and separation of reactant mass transfer coefficients in heterogeneous electrode structures. The method is based on measurements of the limiting current distribution over an electrode area and utilizes operation with highly diluted reagent mixtures (~3-10 vol.% of H2 or O2). Variations in diluent molecular weights (from He to C3H8) and operating conditions allow us to separate a gas phase molecular diffusion, a Knudsen diffusion and a diffusion through ionomer/water films. The validity of the method was demonstrated and proven using commercially relevant flow field design developed byNuvera Fuel Cell and membrane/electrode assemblies with different electrode structures provided by Gore and 3M. Effects of catalyst loading and gas diffusion layer properties on O2/H2 diffusion processes were studied and provided an approach on quantitative separation of different electrode components contribution to the reagents mass transport resistance. Reactant mass transfer coefficients were determined for a wide range of operating conditions and showed an interplay between performance, operating parameters and mass transport phenomena in working heterogeneous electrode structures. Physics-based electrochemical impedance models were developed to understand kinetic and mass transport processes and complement the limiting current distribution methodology.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 25, 2020
- Accession Number
- AD1110971
Entities
People
- Tatyana V. Reshetenko
Organizations
- University of Hawaiʻi System