Side-chain structural engineering on poly(terphenyl piperidinium) anion exchange membrane for water electrolysers

Suppression of hydroxide ions-induced degradation and the increase of hydroxide conductivity in anion exchange membranes (AEMs) are important for realizing high-current-density and durable AEM water electrolyser (AEMWE). Herein, a strategy for mitigating the degradation of membranes is proposed by both inducing the polymer crystalline and tuning the local hydrophilic environment of organic cations, which is achieved by replacing N-alkyl side chains with hydrophilic and flexible N-oligo (ethylene glycol) (OEG) terminal pendants in comb-shaped poly(terphenyl piperidinium) (PTP) AEM. The experimental and simulation results demonstrate the improved ex-situ alkaline stability as well as excellent mechanical property and high conductivity of membranes. As proof of concept, we study the durability of AEMWEs based on PTP-OEG4 membrane under 1 A cm 2, and a lower degradation rate of the cell is observed compared to the control membrane. Our results reveal that stable and conductive AEMs can be practically achieved by side-chain structural engineering, opening a new avenue toward advanced water electrolysis.

Automated summary

A strategy for improving the alkaline stability and conductivity of anion exchange membranes (AEMs) is proposed by replacing N-alkyl side chains with hydrophilic and flexible N-oligo(ethylene glycol) (OEG) terminal pendants in comb-shaped poly(terphenyl piperidinium) (PTP) AEMs. The modified membranes show improved ex-situ alkaline stability, excellent mechanical properties, and high conductivity. This side-chain structural engineering approach opens up a new avenue for advanced water electrolysis.