Conductivity-enhanced Poly(biphenyl piperidine) anion exchange membranes with organic tubes

Abstract

Anion exchange membrane fuel cells (AEMFCs) present an economically efficient alternative to proton exchange membrane fuel cells because of the use of non-precious metals. The development of high-performance and durable AEMFCs necessitates the use of highly conductive and robust anion exchange membranes (AEMs). In this study, a novel organic-organic composite AEM was synthesized by preparing poly(arylene piperidinium) polymer through Friedel-Crafts acid condensation and incorporating one-dimensional organic tubes as reinforcing materials. The composite AEM exhibits high conductivity (235 mS cm⁻¹ at 80 °C) due to the chain orientation within the organic tubes and the availability of abundant transport sites. Furthermore, in contrast to the incompatibility of inorganic materials with polymers, the flexible nature of organic tubes enhanced polymer entanglement, significantly boosting the mechanical strength (120 MPa) of the AEM. Crosslinking the polymer backbone with the organic tubes facilitated simultaneous swelling, effectively mitigating interfacial compatibility issues, result in high dimensional stability. The H₂–O₂ fuel cell employing the developed AEM demonstrated a peak power density of 1018 mW cm⁻² at 80 °C. This study provides a comprehensive synthetic strategy for producing stable AEMs with high hydroxide ion conductivity and outstanding mechanical properties tailored for alkaline membrane fuel cell applications.