Poly(fluorenyl aryl piperidinium) membranes and ionomers for anion exchange membrane fuel cells

Low-cost anion exchange membrane fuel cells have been investigated as a promising alternative to proton exchange membrane fuel cells for the last decade. The major barriers to the viability of anion exchange membrane fuel cells are their unsatisfactory key components-anion exchange ionomers and membranes. Here, we present a series of durable poly(fluorenyl aryl piperidinium) ionomers and membranes where the membranes possess high OH^- conductivity of 208 mS cm^-1 at 80 °C, low H₂ permeability, excellent mechanical properties (84.5 MPa TS), and 2000 h ex-situ durability in 1 M NaOH at 80 °C, while the ionomers have high water vapor permeability and low phenyl adsorption. Based on our rational design of poly(fluorenyl aryl piperidinium) membranes and ionomers, we demonstrate alkaline fuel cell performances of 2.34 W cm^-2 in H₂-O₂ and 1.25 W cm^-2 in H₂-air (CO₂-free) at 80 °C. The present cells can be operated stably under a 0.2 A cm^-2 current density for ~200 h.