Polyolefin-Based Anion Exchange Membranes with Superior Performance and Long-Term Durability for Green Hydrogen Production

In this work, a commercially available styrene-butadiene block copolymer is functionalized with vinyl benzyl chloride (VBC) via solution free-radical polymerization to obtain g-VBC-x graft copolymers. The molar content of VBC, also named functionalization degree (FD) or x, of g-VBC-x is varied in the range 10-27 mol%, simply by varying the concentration of VBC monomer in the feed or the reaction time. The g-VBC-x copolymers are used to prepare films by solution casting that are converted into anionic exchange membranes (AEMs) by heterogeneous quaternization reaction with trimethylamine (TMA). The membranes are extensively characterized to assess their thermal, mechanical, and ex-situ electrochemical properties. The best performing AEMs having an FD of 20% and 27% are tested in an AEM single-cell electrolyzer. Both of them are found to retain their original conductivity after more than 40 and 100 days, respectively. In particular, the membrane with the higher FD is characterized by the best in-situ performance both in terms of ionic conductivity and cell potential. A simple, cost-effective preparation of anionic exchange membranes (AEMs) for the production of green hydrogen is proposed. These AEMs work for more than 40 days at cell operating conditions, display a low and constant potential (1.78 V) at a high current density (816 mA cm-2), and have exceptionally high in-situ ionic conductivity, making them highly promising among those reported in the literature. image