Upscaled production of an ultramicroporous anion-exchange membrane enables long-term operation in electrochemical energy devices.

The lack of high-performance and substantial supply of anion-exchange membranes is a major obstacle to future deployment of relevant electrochemical energy devices. Here, we select two isomers (m-terphenyl and p-terphenyl) and balance their ratio to prepare anion-exchange membranes with well-connected and uniformly-distributed ultramicropores based on robust chemical structures. The anion-exchange membranes display high ion-conducting, excellent barrier properties, and stability exceeding 8000 h at 80 °C in alkali. The assembled anion-exchange membranes present a desirable combination of performance and durability in several electrochemical energy storage devices: neutral aqueous organic redox flow batteries (energy efficiency of 77.2% at 100 mA cm -2 , with negligible permeation of redox-active molecules over 1100 h), water electrolysis (current density of 5.4 A cm -2 at 1.8 V, 90 °C, with durability over 3000 h), and fuel cells (power density of 1.61 W cm -2 under a catalyst loading of 0.2 mg cm -2 , with open-circuit voltage durability test over 1000 h). As a demonstration of upscaled production, the anion-exchange membranes achieve roll-to-roll manufacturing with a width greater than 1000 mm.