New High Temperature Polymer Electrolyte Membranes Based on Poly(ethylene imine) Crosslinked Poly(ether ketone cardo)

A concept of macromolecular crosslinking is applied to prepare high temperature proton exchange membranes (HT-PEMs). Through a simple lactamization procedure, a series of crosslinked membranes are synthesized based on poly(ethylene imine) (PEI) and poly(ether ketone cardo) (PEKcardo). PEI with abundant amino groups endows crosslinked membranes with superior phosphoric acid (PA) absorption capability, resulting in high conductivities. The rigid PEKcardo matrix and constructed crosslinking network significantly improve the dimensional and mechanical stabilities. As an example, the 92%PEI-PEKcardo with a PA doping content of 304%PA achieves a conductivity of 0.107 S cm ⁻¹ at 180 °C without humidifying and a tensile strength of 4.6 MPa at room temperature. The fuel cell performance of abovementioned membrane demonstrates the technical feasibility of the x %PEI-PEKcardo membrane for the HT-PEM fuel cell. This work provides a straightforward method to prepare low-cost and high-performance electrolyte membranes for both fuel cell and other energy devices, such as the vanadium redox flow battery.