Novel side chain grafted poly (biphenyl pyridine-co-N-methyl piperidine) anion exchange membranes for fuel cells

To explore the application of highly conductive and chemically stable anion exchange membranes in anion exchange membrane fuel cells. Herein, a series of novel poly (biphenyl pyridine-co-N-methyl piperidine) (s-PBPP-n-TMA) membranes were synthesized via superacid-catalyzed polymerization. Pyridine units with good thermal stability were added to poly (biphenyl piperidine) with moderately hydrophobic backbones, enhancing the differences and spatial nanostructures between hydrophilic/hydrophobic regions, and constructing obvious microphase separation. Furthermore, flexible hydrophobic alkyl spacer chains with different lengths are grafted at the N of rigid pyridine and piperidine rings, and the formation of multiple cationic sites greatly improves conductivity (>95.63 mS/cm at 80 °C). Compared to membranes without grafted flexible side chain (s-PBPP-80), the addition of side chains inhibits the formation of pyridone and the nucleophilic attack of OH − , resulting in long-term chemical stability of s-PBPP-n-TMA membranes (the residual conductivities were higher than 81.08 % in 2 M NaOH at 80 °C for 1800 h). In terms of single-cell testing, the s-PBPP-6-TMA with the best comprehensive performance achieved a maximum power density of 656.10 mW/cm 2 (H 2 /O 2 ) at 80 °C.