Application of High Phosphoric Acid Retention Nanocomposite Membrane in High-Temperature PEMFC

To address the decline in membrane conductivity caused by phosphoric acid (H3PO4) loss in high-temperature proton exchange membrane fuel cells (PEMFCs), a polybenzimidazole (PBI) membrane modified with zirconia (ZrO₂) nanoparticles was fabricated. The acid-retention capability and proton conductivity of the obtained membranes were investigated. Results showed that at low ZrO₂ loading (PBI/ZrO2-5), the acid-retention capability was inferior to that of pristine PBI. As the ZrO2 content increased, hydrogen-bond interactions in the interface of nanoparticles-polymer matrix-H3PO4 were strengthened, and physical barriers against acid loss were formed. Consequently, acid-retention capability improved and mass loss decreased. Proton conductivity measurements revealed that all membranes showed increased conductivity with temperature (120–180 ℃), and PBI/ZrO2-20 demonstrated superior proton conductivity in the high-temperature range. These results indicate that ZrO2 modification can synergistically enhance both acid retention and high-temperature proton conductivity of composite membranes. However, further optimization of fabrication processes are necessary to support the development of high-temperature PEMFCs.