Revolutionary material stores solar energy for hours after sunset

Revolutionary material stores solar energy for hours after sunset

The latest developments in energy storage promise a future-oriented approach to the use of renewable energy. Researchers of the Technical University of Munich (TUM), the Max Planck Institute for Solid State Research and the University of Stuttgart have developed a novel material that both absorbs sunlight and provides long-term energy storage. This highly porous, two-dimensional organic framework material, a so-called covalent organic framework (COF), is based on naphthalenediimide and allows energy to be stored in an aqueous medium for over 48 hours.

The innovative material stabilizes the charges created during sunlight absorption by influencing the orientation of the surrounding water molecules. This creates an energetic barrier that prevents these charges from recombining. With a storage capacity of 38 mAh/g, it outperforms many existing optoionic materials as well as comparable framework materials and other molecular semiconductors.

Technological functionalities and advantages

The combination of light utilization and long-term storage in a metal-free material opens up new perspectives for energy storage. This development is supported by the e-conversion Cluster of Excellence, which aims to achieve greater efficiency in the conversion and storage of energy. COFs based on reticular and dynamic covalent chemistry offer great potential in the development of advanced energy devices. This is supported by flexibility in design and adjustable porosity of the membranes, which enable new possibilities in energy storage and conversion.

According to the Article Current research provides a comprehensive overview of COF membranes in energy-specific applications, including fuel cells, rechargeable batteries, supercapacitors and photo-osmotic energy conversion. Research activities also focus on synthesis methods and innovative applications of these materials.

Future challenges and opportunities

A significant issue in the field of energy storage is the need to address the use of renewable energy, which is highly dependent on time of day and weather conditions. Alexander Opitz, professor of electrochemical energy conversion at the Vienna University of Technology, emphasizes the importance of new technologies, such as oxygen ion batteries, which do not require critical elements such as lithium or cobalt. These batteries could reduce dependence on geopolitical raw materials and are non-flammable and non-toxic.

By reversibly moving oxygen ions between electrodes at temperatures of 300 to 500 °C, oxygen ion batteries offer significant advantages. This technology is intended to support stationary energy storage by shifting electrical energy from times of high production to times of high demand. Michael Strugl, CEO of VERBUND, emphasizes the urgency of continuous research to advance the transformation of the energy system.

The opening of the Christian Doppler Laboratory for research into oxygen ion batteries represents an important step. It is run by Federal Ministry for Economic Affairs, Energy and Tourism and aims to further develop the practical application capabilities of this technology.