Investigation of freeze/thaw durability in polymer electrolyte fuel cells

Abstract

This study aims to investigate the effect of different gas diffusion layers (GDLs) on freeze/thaw condition durability in polymer electrolyte fuel cells (PEFCs). Three kinds of GDLs–cloth, felt and paper type—with similar basic properties except thickness and bending stiffness were used. The changes in the properties and cell performance were investigated from the −30 to 70 °C range of freeze/thaw cycles. The I–V performance degradation was observed to be negligible for the felt GDL whereas the cloth and paper GDLs showed a marked I–V performance loss. No distinctive correlation between the changes in electrochemical properties, such as active metal surface area, hydrogen crossover rates and decreased I–V performance, was observed except an increase in ohmic resistance revealed by ac-impedance spectroscopy. The physical destruction of electrodes was also shown by scanning electron microscope (SEM) analysis. The present study found that sufficient mechanical supporting force between the interfaces of materials enhances PEFC durability in sub-zero temperature conditions.