A Novel Side-Chain Type Double-Cation Grafted Poly (Binaphthyl Triphenyl Piperidine) Membranes for Anion Exchange Membrane Fuel Cells

Recent advancements in anion exchange membrane fuel cells (AEMFCs) have been primarily driven by improvements in anion exchange membranes (AEMs). Aryl ether bond-free membranes have emerged as a promising avenue for enhancing the overall performance of AEMs. In this study, poly (binaphthyl triphenyl piperidine) with different side-chain degree (PBTP-s-x), possesses double cationic groups, aiming at further enhancing overall performance for AEMs. The use of a twisted stereospecific backbone structure of polymerized binaphthyl and triple biphenyl monomer and grafted side chains of piperidine cationic groups not only improves the microphase separation structure of the membrane, but also improves the alkali resistance. Notably, the PBTP-s-100 AEMs exhibit exceptional OH⁻ conductivity, reaching up to 138.21 mS cm⁻¹, and show outstanding mechanical properties with a tensile strength of up to 28 MPa. Additionally, PBTP-s-100 displays excellent durability, proved by the NMR spectral consistency and over 80 % ion conductivity retention in 1 M NaOH at 60 °C for 4 weeks. And PBTP-s-100 exhibits a higher Lowest Unoccupied Molecular Orbital (LUMO) and a larger energy gap for LUMO and Highest Occupied Molecular Orbital (HOMO) by density functional theory calculation, which indicates it possesses sterling alkaline stability. These findings highlight the potential of PBTP-s-100 as a highly performing polymer structure suitable for anion exchange membranes, which is capable of significantly enhancing the performance of fuel cells.