Conjugated macrocycles for battery electrodes

Organic materials hold great promise for becoming the next generation of battery electrode materials. This project explores a fundamentally new concept for such materials, significantly improving thei r c hemical s tability a nd electronic conductivity. It bridges the gap between research on fundamental effects in organic mater ials a nd the development of ground-breaking applications. Batteries can help to reduce carbon dioxide emissions by storing clean electricity fr om r enewable s ources for periods with high demand and by making the electricity available for the tr a nsport s ector, power ing el ec tric vehicles and other means of transport. However, while batteries and electric vehicles can help to r educ e c arbon dioxide emissions, the widespread use of batteries comes at a cost. There are severe environmental a nd ethic al issues associated with lithium-ion batteries, the type of batteries dominating the electric vehicle market. Furthermore, the future supply of materials required for battery manufacturing is a concern. Most notably, lithium- ion batteries usually require cobalt for their positive electrode, which is often mi ned under ter rible wor king conditions. Organic materials are a promising alternative to electrode materials based on c obalt a nd other hea vy meta ls, considering their advantages of recyclability, structural diversity, fl ex ibility , a nd c ompatibility wi th s odium (replacing the less abundant lithium). In fact, they hold great promise for becoming the next generation of ba tter y electrode materials. However, limited electronic properties and insufficient chemical stability under fast- charge/discharge conditions still impede commercial application of these materials. To solve these issues, this project explores a fundamentally new concept for storing electricity in organic materials, based on so-called conjugated macrocycles. In particular, the research addresses the challenges of achieving high stability and capacity of the organic materials. It will further provide new synthetic strategies and design guidelines for the path towards large-scale application, with the ultimate goal of decreasing carbon dioxide emi ssions i n a n ethical and sustainable way.

Conjugated macrocycles: a promising future for organic battery technology Imagine a battery that's better for the environment, charges faster and stores more energy. That's the potential of conjugated macrocycles, a new class of organic materials explored in this research project. These materials could replace current battery electrode materials, which are often based on heavy metals and require the use of limited resources such as lithium ions. The project focused on a particular type of conjugated macrocycle called paracyclophanetetraene (PCT). The researchers discovered that PCT offers many advantages for battery electrodes. It shows remarkable stability during charge and discharge cycles, charges and discharges quickly, and can have a high energy storage capacity. PCT's unique molecular structure allows it to effectively stabilise both neutral and charged states, which is crucial for ensuring long-term functionality and efficiency in batteries. A key finding was that PCT's macrocyclic structure creates voids in the solid-state packing, which allows the material to accommodate sodium ions, contributing to its excellent performance using these more abundant and less expensive ions. However, the project did not stop at the discovery of PCT as promising material. The researchers also looked at ways to improve PCT for battery applications. By introducing different chemical groups, they were able to fine-tune properties such as stability and capacity. They also investigated methods to reduce the solubility of PCT, a key factor in preventing the electrode material from dissolving in the battery electrolyte. The results of the project show that conjugated macrocycles provide a promising new avenue for battery technology. While further research is needed for practical application, this project has laid the groundwork for significant advances in battery development.