The Effect of Gas Diffusion Layer on the Stability of PEM Unitized Regenerative Fuel Cell

Abstract

Proton exchange membranes(PEM) unitized regenerative fuel cell (URFC) combines the fuel cell (FC) and water electrolyzer (WE) in a single stack. It has been widely considered as energy conversion and storage devices to store off-peak electricity in the form of hydrogen, especially when integrated with intermittent renewable energy resources. One of the main performance challenge in URFCs is material corrosion and the formation of Ti oxides at the interface between titanium surface and anode catalyst layer in WE mode. In this paper, porous sinter titanium as metallic gas diffusion layer (GDL) which is closely related to the anode catalyst layer was coated with IrO2-Ta2O5 oxide materials as protective coating, and the effect of IrO2-Ta2O5 coating on cycle stability of URFCs was validated.As a result, URFCs exhibited that the excellent performance and long-term cycle stability in both FC mode and We mode, what is more, the degradation rate of URFCs was around 1.2% during hundred hours cycle operation in both FC-mode and WE-mode at the current density of 500 mA/cm2. It demonstrated that IrO2-Ta2O5 oxide protective coating improved the corrosion-resistive performance in WE mode and slowed down the formation of Ti oxides at the surface of the metallic GDL. Hence, it further reduced the interfacial contact resistance and improve the cycle stability of URFCs.