Construction of Fluorinated Poly(aryl-piperidinium) Anion Exchange Membranes with High-Speed Ion Transport Channels: Cooperativity of Self-Assembled Fluorinated Side Chains and Piperidinium Cations

Adopting the strategy of grafting side-chain cationic groups to increase OH– transport sites to improve membrane conductivity is advocated. However, it is crucial to improve dimensional stability and chemical stability. First, we controlled the fluorine monomer content in the skeleton and studied its effect on membrane performance. Afterward, we introduced piperidinium cation side chains (containing alkoxy and fluorine end groups) into the optimal skeleton to further explore the effect of side chains on membrane performance. The ionic conductivity of QPTPF5-OPF-40% AEM was 189.58 mS cm–1 at 80 °C. This is because cation–dipole interactions promote cation self-assembly and aggregation. Simultaneously, the fluorinated side chain acts synergistically with the piperidinium cations in the skeleton, constructing continuous ion transport channels. Meanwhile, a distinct microphase separation structure is formed, which promotes conduction. Both the high-rigidity skeleton and cationic groups are rich in superhydrophobic fluorine groups, which can effectively inhibit membrane swelling. In addition, the design of the ether-free skeleton and side-chain fluorination end-group weakening effect improved the alkali resistance of AEMs. QPTPF5-OPF-10% was immersed for 2520 h (80 °C) at 2 M NaOH with 89.65% ion retention. To demonstrate its practicality, the membrane was assembled into a membrane electrode assembly (MEA) for fuel cell performance evaluation. The peak power density (PPD) of the QPTPF5-OPF-40% AEM is 861.99 mW cm–2 at 80 °C and 1.5 bar.