The battery of the future? Research into sodium-ion batteries is making progress

The future of energy supply is set to become more sustainable, and batteries are essential for this. While the demand for energy storage systems was still 700 gigawatt hours in 2022, it is estimated to reach 4,700 gigawatt hours by 2030. In order to meet these developments, more batteries need to be produced - which in turn requires large quantities of raw materials. Lithium-ion batteries have been the standard to date, especially in electromobility, as they have the highest possible energy density per kilogram. However, the raw materials they contain are critical and lithium resources are limited. Researchers around the world have therefore been looking for marketable alternatives for a long time.

According to the current state of research, sodium-ion batteries probably promise the greatest potential. The sodium used for this is obtained from sodium chloride, an abundant raw material. By dispensing with rare and questionable raw materials during production, the sodium-ion battery is therefore more environmentally friendly than its counterpart. Another advantage is that sodium can be procured much more inexpensively than lithium. However, sodium-ion batteries also have disadvantages. One of these is their low energy density, which means that they require considerably more volume to store the same amount of energy. The batteries are therefore significantly larger and heavier, which is why they have so far been used more for stationary applications and are not the ideal solution for electric cars. Various research institutes are trying to tackle these challenges.


Research at the ZSW

The Center for Solar Energy and Hydrogen Research Baden-Württemberg (ZSW) is one of the institutes conducting research into alternative battery technologies in Germany. With the "Four-volt sodium-ion battery" (4NiB) project, the institute is focusing on the more sustainable development of marketable sodium-ion batteries. The Helmholtz Institute Ulm-Karlsruhe with the Institute of Technology (HIU-KIT) and Forschungszentrum Jülich GmbH with the Institute of Energy and Climate Research are also involved in the project. The aim of the project is to develop an environmentally friendly energy storage system for urban transportation and stationary applications.

The focus of the research, however, is the development and coordination of anodes, cathodes and electrolytes in order to produce a high-performance cell with a specific energy of over 200 watt hours per kilogram. The project is being funded by the Federal Ministry of Education and Research (BMBF) with around 1.35 million euros over three years.

NaKlaR joint project

Launched in 2023 and led by the University of Würzburg, the NaKlaR joint project aims to make sodium-ion batteries more electrochemically efficient and improve their sustainability. The recyclability of the components plays a key role in this. Toxic organic solvents are normally used in the production of battery electrodes to mix and apply the components. The aim is to replace the solvents with water - no easy task, as water residues in the electrodes can cause problems in the battery system. This is to be prevented by developing high-performance electrolytes that remain stable in such cases.

In addition to the University of Würzburg, the Karlsruhe Institute of Technology (KIT), the Helmholtz Institute Ulm and the Fraunhofer Institute for Silicate Research (ISC) as well as the R&D Center for Electromobility Bavaria are also involved in NaKlaR. This project is also being funded by the BMBF with around 2 million euros over a three-year period.


DESY research center

The German Electron Synchrotron (DESY), a research center of the Helmholtz Association, is also trying to reduce the weak points of sodium-ion batteries by looking for ways to optimize battery materials. The focus here is on improving the cathodes and the possibility of supplementing the cathode material with foreign elements. Scandium and magnesium are used for this so-called doping in order to test the effects.

Sources: zsw-bw.de, 30.01.2024
chemie.de, 02.04.2024
desy.de, 04.03.2024
uni-wuerzburg.de, 26.02.2024

Image: ThisisEngineering on Unsplash