Nanoporous and redox-active hoops and macrocycles as organic electrode materials for batteries

Project Information

NanOBatt

Grant agreement ID: 101088146

DOI

10.3030/101088146

EC signature date 30 June 2023

Start date 1 November 2023

End date 31 October 2028

Funded under

• European Research Council (ERC)

Total cost

€ 2 000 000,00

EU contribution

€ 2 000 000,00

Coordinated by

UNIVERSITAET ULM
Germany

Periodic Reporting for period 1 - NanOBatt (Nanoporous and redox-active hoops and macrocycles as organic electrode materials for batteries)

Reporting period: 2023-11-01 to 2026-04-30

Summary of the context and overall objectives of the project

Next-generation energy storage solutions are needed to satisfy the increasing demand for electrically powered devices. Organic electrode-active materials (OAMs) are promising candidates, constituted of widely available elements, accessible in processes with low CO2 footprint and easily recycled. However, existing OAMs suffer from a lack of porosity, which inhibits counter ion diffusion to the electroactive sites or renders redox processes irreversible, severely limiting their performance.
NanOBatt explores a fundamentally new concept for OAMs in order to significantly improve their intrinsic porosity and provide pathways for efficient counter ion diffusion. In NanOBatt I and my team are investigating redox-active conjugated nanohoops and macrocycles with intrinsic porosity as OAMs in next-generation batteries: Redox-active groups can be installed with the desired properties, their extended conjugation and aromaticity stabilize charges, and their rigid 3D shapes and nanometer-sized cavities lead to nanoporous structures, ideally suited to enable fast counter ion diffusion. In spite of these outstanding properties, conjugated nanohoops have not been explored as OAMs, and even macrocycles have received only little attention as such.
The aims of NanOBatt are to develop synthetic strategies and design guidelines for redox-active conjugated nanohoops and macrocycles as OAMs, elucidate the role of conjugation and porosity on charge stabilization and ion diffusion in their charge/discharge processes and investigate their application as OAMs in alternative battery cell configurations, namely Na, Al, Mg and all-organic batteries. NanOBatt uniquely bridges the gap between fundamental research on organic materials and their application in next-generation charge storage devices, and it will initiate a new research field with ground-breaking impact.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

In NanOBatt we are developing synthetic strategies and design guidelines for redox-active conjugated nanohoops and macrocycles as OAMs, elucidating the role of conjugation and porosity on charge stabilization and ion diffusion in their charge/discharge processes and investigating their application as OAMs in alternative battery cell configurations.
Over the first part of the project, we made significant progress:
Synthesis of redox-active conjugated nanohoops and macrocycles: We already synthesized a selection of different types of novel redox-active nanohoops, as well as redox-active macrocycles, part of them available in relatively large quantities. We characterized their structures using a range of spectroscopic techniques, and several including by single-crystal X-ray diffraction. This progress allowed us to devise synthetic strategies to selected redox-active new macrocyclic materials.
Electrochemical properties as battery electrode materials in Li-based cells: We explored the electrochemical properties of these redox-active nanohoops and macrocycles in solution and in lithium-organic batteries - each in comparison to appropriate non-cyclic reference compounds. The results show reversible redox behavior and intriguing properties regarding their application as electrode materials.
Exploring the role of conjugation and porosity in their charge/discharge processes in batteries: In several of the synthesized redox-active macrocycles conjugation has a pronounced effect on electrochemical properties, and seems to stabilize charged forms. We are currently in the process of investigating ion diffusion in electrodes of the novel macrocyclic materials, as well as study their charge storage mechanism.
Application in alternative battery cell configurations: Several of the novel redox-active macrocycles show a promising performance in alternative battery cell configurations (i.e. sodium), where battery components (electrolyte, conductive carbon, …) significantly influence their cycling behavior.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The redox-active nanohoops synthesized so far represent a novel type of nanohoop – with high density of redox-active centers. They are of high interest – not only as battery electrode materials with intrinsic porosity – but also as strained aromatic π-systems with intriguing optoelectronic properties.
The newly developed materials and compounds within NanOBatt therefore present highly innovative and beyond-state-of-the art structures, and their redox properties exceed those of reported materials. Key in the following studies will be to decipher the effects of ion diffusion, and to identity suitable post-lithium cell chemistries for the application in full-cells.
With this, NanOBatt uniquely bridges the gap between fundamental research on organic materials and their application in next-generation charge storage devices, and is initiating a new impactful research field.