Researchers are developing high-performance ion exchange membranes for sustainability applications

A team of researchers has achieved a breakthrough in the development of ion exchange membranes (AEMs). They designed a new spiro-branched polymeric membrane that incorporates highly connected sub-nanometer microporous ion channels, showing exceptional performance in flow battery applications. The team included researchers from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences (CAS).

There was study Published Inside Natural sustainability.

AEMs have a wide range of applications including chemical separation, CO₂ conversion, electrochemical ammonia synthesis, water electrolysis for hydrogen production and various energy storage systems. The ability to conduct ions efficiently and reliably is essential to improve the performance and stability of these applications. Traditional methods, primarily through microphase separation, struggle with balancing ion conductivity, selectivity and stability. This often results in exchanges that limit the overall performance of the membrane.

To address these issues, the research team developed a new spiro-branched polymeric membrane using stereotwisted spiro scaffolds and poly(aryl piperidinium) as an all-carbon backbone. This synthesis process involves the formation of a spiro-branched structure that combines the rigidity of the spiro units with the flexibility of the branched chains. This novel configuration aims to improve the free volume within the polymer, which is crucial for creating efficient ion transport pathways.

Furthermore, the researchers conducted detailed structural characterization, including morphological analysis using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and porosity measurements. These analyzes revealed that the membrane forms a semi-flexible 3D loosely packed network that significantly increases the free volume and forms highly connected sub-nanometer ion channels.

Finally, the performance evaluation showed that the spiro-branched polymeric membranes showed exceptional ionic conductivity, with chloride ion conductivity above 60 mS cm.^-1 30°C and reaches up to 120 mS cm^-1 at 80°C. Additionally, in flow battery applications, these membranes showed excellent energy density and energy efficiency, enabling rapid charge and discharge cycles at high current densities of 400 mA cm.^-2. They exhibited excellent chemical stability in vanadium redox flow batteries, indicating potential for long-term use in energy storage systems.

This advance provides a new strategy for membrane material design, capable of addressing various energy and environmental challenges. The research not only advances the field of polymer science, but also paves the way for more efficient and sustainable energy storage technologies.