Polybenzimidazole Confined in Semi-Interpenetrating Networks of Crosslinked Poly (Arylene Ether Ketone) for High Temperature Proton Exchange Membrane

As a traditional high-temperature proton exchange membrane (HT-PEM), phosphoric acid (PA)-doped polybenzimidazole (PBI) is often subject to severe mechanical strength deterioration owing to the “plasticizing effect” of a large amount of PA. In order to address this issue, we fabricated the HT-PEMs with a crosslinked network of poly (arylene ether ketone) to confine polybenzimidazole in semi-interpenetration network using self-synthesized amino-terminated PBI (PBI-4NH2) as a crosslinker. Compared with the pristine linear poly [2,2′-(p-oxdiphenylene)-5,5′-benzimidazole] (OPBI) membrane, the designed HT-PEMs (semi-IPN/xPBI), in the semi-IPN means that the membranes with a semi-interpenetration structure andxrepresent the combined weight percentage of PBI-4NH2and OPBI. In addition, they also demonstrate an enhanced anti-oxidative stability and superior mechanical properties without the sacrifice of conductivity. The semi-IPN/70PBI exhibits a higher proton conductivity than OPBI at temperatures ranging from 80 to 180 °C. The HT-PEMFC with semi-IPN/70PBI exhibits excellent H2/O2single cell performance with a power density of 660 mW cm−2at 160 °C with flow rates of 250 and 500 mL min−1for dry H2and O2at a backpressure of 0.03 MPa, which is 18% higher than that of OPBI (561 mW cm−2) under the same test conditions. The results indicate that the introduction of PBI containing crosslinked networks is a promising approach to improve the comprehensive performance of HT-PEMs.Keywords:high-temperature proton exchange membrane;semi-interpenetration network;phosphoric acid;poly [2,2′-(p-oxdiphenylene)-5,5′-benzimidazole]