High-efficiency anion exchange membranes based on fluorinated grafted poly (aryl piperidines): Achieving good ionic conductivity and dimensional stability

The development of anion-exchange membrane water electrolyzers (AEMWE) offers significant potential for sustainable hydrogen production, but the practical adoption of anion exchange membranes (AEMs) is hindered by their inherent performance limitations. To overcome this challenge, we developed a series of poly (biphenylene-co-1,2-diphenylethane) piperidine AEMs featuring grafted hydrophobic fluorinated side chains by precisely controlling the grafting rate. The fluorinated side chains not only promote microphase separation and reduce ionic conduction resistance, but also significantly enhance the dimensional stability of the AEMs. Specifically, the QPBDP-TF-40 membrane exhibits good ionic conductivity (163.6 mS cm⁻¹ at 80 °C), and with increasing grafting rate the QPBDP-TF-80 membrane exhibits low swelling rate (16 % at 80 °C). QPBDP-TF-60 shows good chemical stability with ionic conductivity retention of 78.3 % after 1000 h immersion in 2 M NaOH solution at 80 °C. In addition, the membrane electrode assembled based on QPBDP-TF-40 membranes exhibits considerable current density in AEMWE (1.36 A cm⁻² achieved at 2.1 V) and stable operation at a current density of 500 mA cm⁻² for 72 h. The above results indicate that fluoride-grafted QPBDP-TF-X exhibits a large potential for application in AEMWE.