Poly(p-terphenylene piperidinium)s with perfluoroalkyl side chains for high-performance anion exchange membranes

Abstract

Anion exchange membranes (AEMs) are essential components in alkaline polymer electrolyte fuel cells. However, the primary challenges for AMEs in fuel cell applications include insufficient alkaline durability and sluggish ion transport efficiency. In response, we here present a side chain fluorination strategy to construct nanoscale phase-separated morphologies in poly(arylene piperidinium)s, leading to percolated hydrophilic domains with high ion transport efficiency. The synthesized perfluoroheptyl-tethered poly(p-terphenylene piperidinium)s (FPTPs) show an excellent conductivity (175 mS cm⁻¹ at 80 °C) and a high ion diffusion coefficient (2 × 10⁶ cm² s⁻¹ in Cl⁻ form membrane at 30 °C) at a relative low ion content (∼2.0 mmol g⁻¹). They also show good dimensional stability (<15 % swelling at 80 °C) and improved alkaline stability (2.6 % piperidinium group loss after 1000 h in 1 M NaOH at 80 °C). An H₂–O₂ fuel cell prototype fabricated with FPTP-15 achieves a high peak power density of 0.89 W cm⁻². Additionally, short-term cell operation at 50 °C demonstrates good durability of over 100 h at 0.2 A cm⁻², showing a slight voltage increase of 160 μV h⁻¹.