Elucidating the role of alkyl chain in poly(aryl piperidinium) copolymers for anion exchange membrane fuel cells

Poly(aryl-co-aryl piperidinium) (c-PAP) has recently attracted wide attention in anion exchange membrane (AEM) fuel cells (AEMFCs). Here, we report poly(aryl-co-terphenyl piperidinium)-x (PDnTP-x) AEMs with different alkyl spacers (n = 0, 1, 2, 6, 10) in the backbone. Long alkyl chains (n = 6 or 10) improved the dimensional stability and gas tightness (H-2 permeability <10 Barrer) of membranes, while short-chain-type PDnTP-x membranes displayed higher ion conductivity (>150 mS cm(-1) at 80 degrees C). All the PDnTP-x membranes possessed excellent alkaline stability (1 M NaOH at 80 degrees C for 1000 h) and oxidative stability (200 h in Fenton's reagent). Short-chain-type PD0TP-x based AEMFC reached a new-record power density of 2.67 W cm(-2) at 80 degrees C in polyaromatic AEMFCs, which is higher than that of long-chain-type cells (1.7 W cm(-2)). The short-chain-type PDnTP-x AEMFCs can run stably under a 0.4 A cm(-2) current density for 220 h with a low voltage decay rate of similar to 77 mu V h(-1).

Automated summary

Poly(aryl-co-aryl piperidinium) (c-PAP) has attracted attention in anion exchange membrane fuel cells. In this study, poly(aryl-co-terphenyl piperidinium)-x (PDnTP-x) AEMs with different alkyl spacers were investigated. Long alkyl chains improved dimensional stability and gas tightness, while short-chain-type membranes exhibited higher ion conductivity. All membranes showed excellent alkaline and oxidative stability. Short-chain-type PD0TP-x based AEMFC achieved a new-record power density and stable operation.