Side-Chain Dual-Cation Poly(aryl quinuclidinium) Anion Exchange Membranes with Very-High Hydroxide Conductivity

With the rapid development of the anion exchange membrane (AEM) industry, efficient and low-cost production of AEM has become a critical focus for industrial applications. By using long-side-chain brominated alkanes bearing trimethylammonium quaternary ammonium groups instead of iodomethane for Menshutkin methylation, we synthesized poly(aryl quinuclidinium) with long-side-chain dual cations (PPTQ-xC-QA). This approach not only streamlines the production process-avoiding the drawbacks associated with iodomethane such as high volatility, toxicity, and potential carcinogenicity─but also introduces additional cationic groups that lead to very-high hydroxide ion conductivity (260.1 mS·cm –1 at 80 °C) and a water uptake of 70% with only 19% swelling at 80 °C. When assembled with commercially available nickel–alloy foam electrodes in AEM water electrolyzer, the system achieved a current density of 2.42 A·cm –2 at 2.0 V. The electrolysis stability test showed a low decay rate, e.g., 67 mV h –1 for 1400 h at 0.5 A·cm –2 and 82 mV h –1 for 800 h at 1 A·cm –2 .