Di-piperidinium-crosslinked poly(fluorenyl-co-terphenyl piperidinium)s for high-performance alkaline membrane fuel cells

Abstract

Modern anion exchange membrane (AEM) fuel cells (AEMFCs) call for highly conductive, durable, and mechanically tough AEMs and ionomers. Here, we report a series of scalable di-piperidinium-crosslinked poly(fluorenyl-co-terphenyl piperidinium) (x-PFTP-DP-Cn) copolymers with high ion exchange capacity (IEC) and tunable crosslinking alkyl spacers (Cn, n=5 or 10) to reinforce the mechanical strength and optimize the electrochemical performance of poly(aryl piperidinium)-based AEMFCs. Specifically, durable x-PFTP-DP AEMs display high ion conductivity (HCO3− >90 mS cm-1 and OH− >180 mS cm-1 at 90 oC) and excellent mechanical strength (tensile strength ~90 MPa, elongation at break ~35%). Importantly, the x-PFTP-DP-based AEMFCs achieve outstanding peak power densities of 2.50 W cm-2 in H2-O2 and ~1.41 W cm-2 in H2-air at 80 oC. Moreover, the present AEMFCs can run stably under 0.2 A cm-2 and 0.6 A cm-2 current densities at 70 oC for 265 h and 110 h, respectively, with low voltage decay rate of ~ 50 μV h-1.