Synthesis and Properties of Polysilsesquioxane Functionalized Poly(p-terphenyl-co-N-methyl-4-piperidine) Membrane for High Temperature Proton Exchange Membrane Fuel Cells

The development of high-performance, cost-effective high temperature polymer electrolyte membranes (HT-PEMs) is a great challenge for HT-PEM fuel cells. In this study, a new HT-PEM of polysilsesquioxane functionalized poly(p-terphenyl-co-N-methyl-4-piperidine) (PTP-CPTMS) is reported. Owing to the incorporation of the polysilsesquioxane network, the PTP-CPTMS membrane demonstrates an excellent phosphoric acid (PA) doping capacity and controlled swelling, compared to the benchmarks, that is, pristine PTP membrane and propyl group grafted PTP membrane (PTP-C3). As a result, the PTP-CPTMS/208%PA membrane exhibits a low volume swelling of 77%, a high conductivity of 0.070 S cm⁻¹ at 180 °C and a satisfactory tensile strength of 4.9 MPa at room temperature. Based on the above membrane, the H₂-O₂ single cell is assembled and displays a steadily increased peak power density up to 220 °C, which is 769 mW cm⁻² without the need for external humidification or backpressure. This work provides a kind of polysilsesquioxane functionalized HT-PEMs, which hold substantial potential for application in HT-PEM fuel cells.