An antioxidant polybenzimidazole with naphthalene group for high-temperature proton exchange membrane fuel cells

One significant challenge to the durability of HT-PEMFCs is the susceptibility of PBI HT-PEMs to electrophilic free radicals, such as ∙OH and ∙OOH. In this study, the development of a N-PBI membrane with low C2 electron cloud density was explored as a potential solution to achieve good oxidative stability of HT-PEMs. The physicochemical properties of PBI membranes before and after the Fenton test were studied in terms of chemical structure, molecular weight, mechanical properties, and thermal stability. The results indicate that incorporating naphthalene ring into the molecular structure of PBI significantly enhances its oxidative stability compared to P-PBI with high electron cloud density C2 atom and copolymerized P0.5-N0.5-PBI. In addition, with a saturated ADL of 12.9, the PA-doped N-PBI membrane achieves an acceptable compromise between mechanical properties and proton conductivity, thus resulting a H2/O2 fuel cell PPD of 625 mW/cm2 at 160 °C. This work presents a theoretical basis for pursuing PBI membranes with greater oxidative stability.