A simple method to measure through-plane effective gas diffusivity of a gas diffusion layer for polymer electrolyte fuel cells

Abstract

Gas diffusivity in a gas diffusion layer for polymer electrolyte fuel cells is strongly related to the fuel cell performance. In this work, we develop a straightforward experimental apparatus for measuring the through-plane effective diffusion coefficient in gas diffusion layers. The apparatus consists of an infrared absorption carbon dioxide sensor and a custom-built sample holder. The gas chamber of the sensor is separated from the air by gas diffusion layers in the sample holder. After the gas chamber is purged with carbon dioxide through the gas diffusion layer, its decay is examined. The decay curve is fitted using Fick's law for one-dimensional diffusion, and the diffusivity is calculated by dividing the effective diffusion coefficient by the bulk diffusion coefficient. As a case study, we examined the gas diffusivity for a commercial carbon paper (TGP-H060, Toray). The calculated diffusivity for TGP-H060 was evaluated to be 0.36 ± 0.02 at 25 °C. This value is consistent with the data presented in previous reports.