Effect of PTFE Concentration in PPS Based Microporous Layer Hydrophobic Agents on the Electrochemical Characteristics of PEMFCs

Polyphenylene sulfide (PPS) exhibits remarkable thermal and chemical stability, making it widely applicable in hydrophobic modification. Previous research has validated the feasibility of using PPS as a substitute for conventional polytetrafluoroethylene (PTFE) to enhance the hydrophobicity of the microporous layer (MPL) in proton exchange membrane fuel cells (PEMFCs). However, the low melt viscosity of PPS enables the penetration of carbon particles from MPL into the gas diffusion layer during preparation, resulting in reduced porosity. This research reduces this effect by incorporating various amounts of high melt viscosity PTFE into the PPS ink. Five MPLs were prepared with various ratios of PPS and PTFE to vary the hydrophobicity with comparisons of their pore structure characteristics and electrochemical properties. The findings indicated that the incorporation of a small amount of PTFE (5 wt%) effectively mitigated the penetration of carbon clusters, thereby enhancing the porosity. The MPL containing 15 wt% PPS and 5 wt% PTFE exhibited the best electrochemical performance with the peak power increased by 8.60% compared to an MPL with pure PPS and by 6.08% compared to a conventional MPL with only PTFE. Various thickness MPLs were then prepared with this best ratio with the 50 μm thick MPL giving the best PEMFC performance.