Rationale: Anion exchange membranes (AEMs) remain plagued by either low stability in an alkaline environment or low ionic conductivities. To overcome these challenges, careful consideration of the chemical structure of both the polymer backbone and the cationic head group is required.
Objectives: The COFFEE project addresses these challenges by proposing a novel class of AEMs based on covalent organic frameworks (COFs) to promote enhanced membrane stability, conductivity, and selectivity.
Potential applications: Key applications for the COF-based AEMs will be AEM water electrolysers and zinc-air batteries.
Impact & potential benefits: The development of durable, high-performance AEMs will push these developmental technologies closer to commercial viability. The successful commercialisation of low-cost electrolyser and battery technologies will contribute to the widespread adoption of renewable energy solutions and directly support Europe's greenhouse gas emission reduction targets.
The COFFEE project seeks to combine research expertise across multiple areas of materials chemistry, to develop innovative anion exchange membrane (AEM) solutions for electrochemical energy conversion and storage technologies. This innovative project employs a bottom-up approach to membrane design that aims to overhaul the traditional AEM designs that rely exclusively on linear cationic polymers and instead develop an entirely new class of membranes based on covalent organic frameworks (COFs). By functionalizing the inside of the cyclic COF structures with cationic groups, we can provide hydroxide conductivity properties to the synthesized COFs. The functionalized COFs then undergo self-assembly to form highly ordered nanochannels, enabling ultrafast hydroxide ion transport through the COF structure. These highly ordered COF structures will then be embedded in a polymer matrix to form membranes with an optimal balance of ionic conductivity and mechanical stability.
A key feature of the COFFEE project is the highly tunable nature of the membrane properties through the careful selection of the molecular building blocks used in the COF synthesis. By building up a library of molecular building blocks and understanding their influence on the structure-property-performance relationship of the final membranes, we will be able to successfully predict membrane properties and provide tailor-made membranes for a range of ion exchange membrane-based technologies.
The versatility of our membrane design strategies will be demonstrated by producing membranes optimized for two separate electrochemical energy applications. As AEMs have gained significant research attention in the areas of electrolysis and solid-state batteries, we will focus our demonstration efforts on anion exchange membrane water electrolysis (AEMWE) and zinc-air battery (ZAB) technologies.