Poly (biphenyl-isatin-piperidine) anion exchange membrane with high hydroxide conductivity based on hydrophilic alkoxy spacer chains

Anion exchange membrane (AEM) with excellent electrical conductivity and high stability has become the main goal of the development of high performance fuel cells. In this work, in order to improve the performance, we will select an effective design strategy with an ether-free (biphenyl-isatin-piperidine) polymer as the main chain. After amination of the chain, the high alkaline resistant piperidine cation serves as a functional group to enhance the alkaline resistance of AEM. At the same time, the hydrophilic flexible spacer chain is introduced to create the phase separation morphology of hydrophilic and hydrophobic water, and to further improve the ion transmission efficiency. It is noteworthy here that PBIP-90-TGM-5 AEM can reach the hydroxide conductivity of 134.21 mS cm−1 at 80 °C, and the prepared PBIP-90-TGM-5 AEM have obvious nanoscale microphase separation morphology, which ensures the membrane has good mechanical properties and dimensional stability. On this basis, PBIP-90-TGM-5 also showed good alkaline stability, and the retention rate was still 81.41 % after 1152 h of 5 M NaOH aqueous solution. At the same time, the peak power density of PBIP-90-TGM-5 at a temperature of 80 °C and an open circuit voltage of 0.94 V can reach 235.7 mW cm−2. This study confirms that poly (biphenyl-isatin-piperidine) has great potential as an AEM for fuel cells.