Octopus-like side chain grafted poly(arylene piperidinium) membranes for fuel cell application

Octopus-like side chains are introduced in poly(arylene piperidinium)-based alkaline anion exchange membranes (AEMs) to enhance the conductivity and stability. This type of side chain consists of a bulky rigid beta-cyclodextrin (beta-CD) as the octopus head, and long flexible piperidinium ionic liquids as the arms. The beta-CD unit can enlarge internal free volume of the AEM to reduce ion transport resistance; the arms can interact with adjacent hydrophilic ionic groups and water, constructing continuous ion transport channels. The prepared poly(biphenyl piperidinium) AEM with octopus side chains at an ion exchange capacity (IEC) of 1.29 mmol g-1 exhibits higher hydroxide conductivity (121.5 mS cm-1 at 80 degrees C) than that without the octopus structure (57.4 mS cm-1) although the latter has a larger IEC (1.55 mmol g-1). This octopus AEM retains 87.2% of its conductivity after being treated in a 1 M NaOH at 80 degrees C for 480 h. The alkaline H2/O2 fuel cell constructed with this octopus AEM produces a peak power density of 469 mW cm-2; the cell voltage can be maintained by 85% during 16 h operation. This work illustrates the advantage of octopus side chain for enhancement of AEM performance.

Automated summary

Introducing octopus-like side chains in alkaline anion exchange membranes enhances conductivity and stability, leading to higher ion conductivity and durability. The use of these side chains in AEMs demonstrates improved performance in hydrogen/oxygen fuel cells.