In-situ analysis of water transport properties through a reinforced composite membrane in polymer electrolyte membrane fuel cells

Abstract

This study presents a comprehensive in-situ analysis of water transport properties through an expanded polytetrafluoroethylene (ePTFE)-reinforced composite membrane, representing a notable advancement over previous studies that primarily focused on Nafion membranes. The membrane water content was measured using dynamic vapor sorption (DVS) isotherms, and the temperature dependence of sorption was investigated using a new dual-mode sorption (NDMS) model, which showed an excellent fit with an adjusted coefficient of determination (Radj2) greater than 0.96. By employing the hydrogen pumping mode and polymer electrolyte membrane fuel cells (PEMFC) mode, we established empirical correlations for the coefficients of water diffusion, electro-osmotic drag (EOD), and ionic conductivity as functions of water content and cell temperature. The correlation results exhibited a maximum relative error of less than 3.14 %. In addition, we isolated the water diffusion coefficients of the gas diffusion layer (GDL) and catalyst layer (CL) from the membrane to refine our analysis. This study enhances the understanding of water management in PEMFCs by establishing correlations for water diffusion, EOD coefficient, and ionic conductivity. These findings underscore the potential of reinforced composite membranes in advancing fuel cell technology by optimizing water transport, which is crucial for improving fuel cell performance and enabling more precise PEMFC modeling.