Improvement in physical properties of single-layer gas diffusion layers using graphene for proton exchange membrane fuel cells

Abstract

Gas diffusion layer (GDL) is an important component related to the efficiency of proton exchange membrane fuel cells (PEMFCs). Nevertheless, the preparation cost of the conventional GDL is high. In our previous studies, a single-layer gas diffusion layer (SL-GDL) prepared by a simple and cost-effective process has been used for PEMFCs, and it achieved 85% efficiency of a commonly used commercial GDL. In this study, improvement in physical properties of a series of single-layer gas diffusion layers, SL-GDL-Gx (x = 1–3), via uniform distribution of graphene in the SL-GDL, and the application of SL-GDL-Gx in PEMFCs are studied. The results indicate that the presence of well-distributed graphene layers in SL-GDL-Gxs causes an increase in the surface roughness and the formation of irregular slender interstices, leading to the enhancement of gas permeability while maintaining the microporous layer (MPL)-like microstructure and retaining good loading and efficient utilization of the catalyst. Moreover, the electrical resistivities significantly decreased and the mechanical properties improved. These improvements in physical properties are significantly beneficial for the performance of PEMFC. The single-cell performance tests show that the best performance measured at 80 °C under 99.9% relative humidity (RH) conditions is obtained from the PEMFC (FC-2) fabricated with SL-GDL-G2 and is 46% higher than that from FC-0 with SL-GDL-G0 without graphene and 15% higher than that from FC-3 with the commercial GDL. Furthermore, the performances of FC-2 measured at 50–80 °C under 15% RH are all much higher than those of FC-3. The results indicate that SL-GDL-G2 prepared via a cost-effective method is a potential GDL for PEMFCs.