High Free Volume Polyelectrolytes for Anion Exchange Membrane Water Electrolyzers with a Current Density of 13.39 A cm−2 and a Durability of 1000 h

Abstract

The rational design of the current anion exchange polyelectrolytes (AEPs) is challenging to meet the requirements of both high performance and durability in anion exchange membrane water electrolyzers (AEMWEs). Herein, highly-rigid-twisted spirobisindane monomer is incorporated in poly(aryl-co-aryl piperidinium) backbone to construct continuous ionic channels and to maintain dimensional stability as promising materials for AEPs. The morphologies, physical, and electrochemical properties of the AEPs are investigated based on experimental data and molecular dynamics simulations. The present AEPs possess high free volumes, excellent dimensional stability, hydroxide conductivity (208.1 mS cm−1 at 80 °C), and mechanical properties. The AEMWE of the present AEPs achieves a new current density record of 13.39 and 10.7 A cm−2 at 80 °C by applying IrO2 and nonprecious anode catalyst, respectively, along with outstanding in situ durability under 1 A cm−2 for 1000 h with a low voltage decay rate of 53 µV h−1. Moreover, the AEPs can be applied in fuel cells and reach a power density of 2.02 W cm−2 at 80 °C under fully humidified conditions, and 1.65 W cm−2 at 100 °C, 30% relative humidity. This study provides insights into the design of high-performance AEPs for energy conversion devices.