Determination of PEFC Gas Diffusion Layer and Catalyst Layer Porosity Utilizing Archimedes Principle

Abstract

Porous media transport properties, such as permeability and diffusivity, are proportional to the porosity of the sample, thereby making the ability to quickly estimate porosity of paramount importance. A simple and inexpensive setup, free of hazardous chemicals, is proposed to measure the total porosity and thickness of polymer electrolyte fuel cell (PEFC) diffusion media. The experimental setup is based on Archimedes’ principle. It uses a combination of a wetting (n-octane or IPA) and a non-wetting (water) fluid to estimate both the solid and bulk sample volumes of the porous media, and then these values are used to estimate the porosity. The results from the proposed setup were validated using mercury intrusion porosimetry, scanning electron microscopy imaging, and compressive thickness measurements for a range of commercial gas diffusion layer and in-house fabricated catalyst layer samples. The values for porosity and thickness from the setup were in reasonable agreement with those obtained by the other methods.