The Influence of Gas Diffusion Media Morphology on Hydrogen Fuel Cell Performance

Abstract

Gas diffusion media (GDM) is an integral part of all gas diffusion electrodes because it facilitates both the transport of reactants to the electrocatalyst surface and the removal of reaction products from the system. Proper reactant/product distribution is critical for high power operation in polymer electrolyte fuel cells (PEMFCs) because oxygen transport and water rejection determine the maximum current density that can be obtained from PEMFCs. This paper will discuss NRL’s research on how GDM morphology influences cell performance in both closed-cathode fuel cell and open-cathode fuel cell designs. The comprehensive study linking the influence of compression on the GDM micro and macro structure morphology will be presented using micro X-ray computed tomography (μ-CT), scanning electron microscopy (SEM), N 2 Physisorption (BET) and traditional electrochemical characterization techniques (CV, Pol. Curves, etc.). Optimal GDM selection for the challenge of open-cathode operation will be presented and related to water retention through rational morphology selection. The relationship between high power performance and water transport will be elucidated and the goals for future GDM properties will be proposed for use in unmanned systems

Key findings

• ▸GDM morphology affects reactant/product distribution, impacting maximum current density in PEMFCs.
• ▸Compression influences GDM micro and macro structure morphology, affecting cell performance.
• ▸Optimal GDM selection for open-cathode operation is linked to water retention through rational morphology selection.

Keywords

Identifiers

DOI

10.4028/www.scientific.net/msf.941.2226

Journal

Materials Science Forum

Year

2018