Cyanated macrocycles for electron and ion transport

Informations projet

CYMEIT

N° de convention de subvention: 796024

DOI

10.3030/796024

Projet clôturé

Date de signature de la CE 26 Mars 2018

Date de début 1 Septembre 2018

Date de fin 31 Août 2020

Financé au titre de

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Coût total

€ 183 454,80

Contribution de l’UE

€ 183 454,80

Coordonné par

IMPERIAL COLLEGE OF SCIENCE TECHNOLOGY AND MEDICINE
United Kingdom

Periodic Reporting for period 1 - CYMEIT (Cyanated macrocycles for electron and ion transport)

Période du rapport: 2018-09-01 au 2020-08-31

Résumé du contexte et des objectifs généraux du projet

Organic materials hold great promise for applications that require both electron and ion transport. This project explored, if the unique properties of cyclic organic molecules known as π-conjugated macrocycles can help to obtain electron and ion transporting materials with excellent performance. It aimed to bridge the gap between research on fundamental effects in organic materials and the development of ground-breaking applications.

Battery electrodes are a potential application of such materials. Batteries can help to reduce carbon dioxide emissions by storing clean electricity from renewable sources for periods with high demand and by making the electricity available for electric vehicles and other means of transport. However, there are severe environmental and ethical issues associated with the currently used heavy metal-based electrode materials. Organic materials, such as those developed during this project, can provide a more sustainable alternative.

The overall objective of the project was to develop redox-active π-conjugated macrocycles for excellent electron and ion transporting materials and to apply these materials in devices. It can be concluded that such materials can indeed be obtained. The developed macrocycles showed outstanding performance in battery electrodes under fast‐charge/discharge conditions as well as extraordinarily stable cycling performance. The macrocyclic geometry of the molecules and the related properties were found to be highly beneficial for this application.

Travail effectué depuis le début du projet jusqu’à la fin de la période considérée dans le rapport et principaux résultats atteints jusqu’à présent

The work carried out during the project consisted in the development of synthetic routes towards redox-active π-conjugated macrocycles capable of transporting both electrons and ions (with an initial focus on the development of synthetic routes to cyanated macrocycles) and in the investigation of their properties. Such mixed ionic-electronic conductors are important for various state-of-the-art applications, for example organic battery electrodes, electrochemical transistors, electrochromic devices, and light-emitting electrochemical cells. Before this project, macrocycles were considerably underexplored regarding these applications.

While the synthesis of cyanated macrocycles was found to be challenging via the proposed synthetic routes, the synthesis of π-conjugated macrocycles with other electron-withdrawing groups was highly successful. In line with the objectives of the project, π-conjugated macrocycles with different aromatic units were synthesised and their properties were investigated. The investigation of the properties has advanced our fundamental understanding of such compounds. The subsequent work on applications has exceeded the expectations by far. The cyclic shape of the molecules was found to be highly beneficial for application as organic battery electrode materials. Even the simplest compound paracyclophanetetraene, a macrocycle without substituents synthesised as a reference compound for the substituted macrocycles, performed surprisingly well when tested as anode material in sodium-ion batteries. These results were recently published (Angew. Chem., Int. Ed. 2020, 59, 12958-12964).

Progrès au-delà de l’état des connaissances et impact potentiel prévu (y compris l’impact socio-économique et les conséquences sociétales plus larges du projet jusqu’à présent)

The project has shown that π-conjugated macrocycles are an attractive class of organic compounds for battery electrode materials and related applications. It has introduced new concepts and approaches for the design of redox-active macrocycles and has expanded the synthetic toolbox for their synthesis. The results and discoveries advance our understanding of the properties of π-conjugated macrocycles (and how they can be tailored for specific applications) and show that they can contribute to future innovation in the important area of energy storage. If further research based on these results can solve the remaining issues, the outcome will help to address the environmental concerns associated with the currently used battery technology by providing a more sustainable, organic alternative to heavy metal-based electrode materials.

The results of the project will significantly contribute to the further development of organic materials for battery electrodes and related applications. The project has also provided exciting new insights into the fundamental properties of π-conjugated macrocycles related to local and global (anti)aromaticity in such molecules.

Distribution of the electrons in a macrocycle of the battery electrode after charging

Empty space (blue) in the battery electrode material, which can be occupied by ions when charged