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

Abstract

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.

Alkaline Membranes toward Electrochemical Energy Devices: Recent Development and Future Perspectives

“…100 Besides, our group recently provided a type of cross-linked MTCP-50 membrane, as shown in Figure 8f. 101 The membrane demonstrated exceptional durability in neutral aqueous organic redox flow batteries (negligible permeation of redox-active molecules over 1100 h), water electrolyzers (durability over 3000 h), and fuel cells (open-circuit voltage durability test over 1000 h). This outstanding durability is inseparable from the membrane ex situ stability, which shows 94.3% conductivity retention even after 8000 h alkali aging.…”

“…(d) Representative membrane structure with interactions between molecular chains. , (e) Chemical structure of branched poly­(terphenyl piperidinium)­s and its durability in fuel cells . (f) Chemical structure of cross-linked MTCP-50 and its durability in neutral aqueous organic redox flow batteries, water electrolyzers, and fuel cells (open-circuit voltage durability) . Reproduced with permission from refs , , , , and .…”

“…Generally, the rigidity and flexibility of the polymer backbone positively affect tensile strength (TS) and elongation at break ( E b ), respectively. For instance, the rigid nature of polyaromatic hydrocarbon-based alkaline membranes enables it to have higher TS (generally >30 MPa). ,, The typical polyolefin-based alkaline membranes usually display extraordinary E b (generally >100%). , For poly­(arylene ether)-based alkaline membranes, the TS is generally <30 MPa while E b < 20%. , A good balance between TS and E b should be considered in molecular design to obtain the optimum mechanical properties of the material. Another thing that needs to be accounted for in addition to tensile testing to evaluate the membrane mechanical properties is compressive stress, which is the main force the membrane is subjected to in the device.…”

Manipulation of Cationic Group Density in Covalent Organic Framework Membranes for Efficient Anion Transport

“…In recent years, anion exchange membranes (AEMs) have attracted extensive attention in energy-related applications due to more facile reaction kinetics in basic environments, such as fuel cells, electrolyzers, batteries, and carbon dioxide separators. − AEMs with high anion conductivity are highly desired for high-efficiency electrochemical devices . Increasing ion exchange capacity (IEC) and hence charge carrier concentration is identified as a straightforward and facile approach to enhancing ion conductivity. − However, there always exists a trade-off between IEC and dimensional stability, as high IEC often results in excessive water uptake and further increased swelling degree of the membrane. − Generally, the dimensional stability of the ion exchange membrane depends primarily on the interaction between backbones − and the ion conductivity depends primarily on IEC and channel morphology under identical environmental conditions. − Therefore, an ideal anion conductor should bear robust and stable backbones with a strong intermolecular interaction to ensure high dimensional stability and ordered channels precisely decorated with abundant ionic groups to achieve rapid anion transport.…”

Development of highly conductive anion exchange membranes based on crosslinked PIM-SEBS with high free volume

“…These studies have focused on the development of not only non-noble metal catalysts but also AEM materials with improved physical, chemical, and electrochemical stability and enhanced conductivity comparable to the characteristics of perfluorocarbon-based PEMs, including Nafion. 8–12…”