Sodium-Ion Technologies

Im Bereich „Natrium-Ionen-Technologien“ beschäftigen wir uns mit der Herstellung und Entwicklung von Elektroden sowie Anoden- und Kathodenmaterialien für diese Form der Speichertechnologie.

Sodium-ion battery (NIB) technologies are experiencing an increasing interest and offer an alternative to lithium-ion batteries (LIB) for both stationary storage and mobile applications. The high natural abundance of sodium itself and of the elements used for the active materials allows these batteries to be made from materials with good availability, low cost and less price volatility.

As NIBs operate in the same way as LIBs ("rocking chair principle"), a lot of knowledge and experience can be transferred. Particularly in the areas of active material production, electrode production and cell assembly, this technology can be used as a drop-in replacement, as it uses similar production processes to LIBs and can therefore be integrated into existing production lines without major adjustments.

The size of the sodium ions, which are larger than the lithium ions, is a significant difference between the two technologies. This difference in size influences, among other things, the choice of active materials, which currently have a lower energy density than LIBs.

Overall, NIBs have great potential and, with further research and development, offer a sustainable and cost effective solution for storing energy.

Our R&D-Services on the Topic »Sodium-Ion Technologies« Include:

• Synthesis of Hard Carbons as Anode Active Materials
• Synthesis of Cathode Active Materials
• Electrode Development for Sodium-Ion Batteries
• Up-Scaling of Sodium-Ion Batteries

Hard carbon, which can be produced from synthetic or biological precursors, is the main active material used on the anode side for sodium-ion batteries. The scientific focus at Fraunhofer ISE is on the thermal treatment of biological precursors such as sawdust or coffee. Furnaces of various sizes are available for this purpose, enabling the synthesis of up to 5 kg of active material per day. With the help of our in-house characterization laboratory, important parameters such as morphology, pore size or BET surface area of the active material can be determined. In addition, we are researching coatings that reduce initial losses and thus increase capacity.

At Fraunhofer ISE, we have various options for synthesizing cathode active materials for sodium-ion batteries. On the one hand, the active materials can be produced via the solid-state route. Another option is a precipitation reactor for synthesizing precursors (with a total volume of 2 L). After mixing the precursors with an sodium source, they are sodiiated by thermal processes. At Fraunhofer ISE, we are primarily focusing on the production of layered transition metal oxides, which can be produced from sustainable and highly available materials.

We have extensive experience in the design and manufacture of electrodes for sodium-ion batteries. In addition to the conventional solvent-based production of electrodes, we also conduct research in the field of dry coating at Fraunhofer ISE. For slurry-based electrode production, we focus on the use of PFAS-free binders and the use of non-toxic solvents (e.g. water). In the field of dry coating, we work with different methods of powder pre-treatment and different binder systems.

After successfully validating the materials and electrode compositions on a laboratory scale, we at Fraunhofer ISE are able to scale up all processes. An infrastructure for synthesizing up to 5 kg per day is available for the synthesis of active materials. The electrode formulations can then be tested on the roll-to-roll coater using a slot die (from Q1/2025). The semi-automatic pouch cell assembly system enables the production of sodium-ion-based pouch cells of up to 20 Ah. The scaling of materials and processes on a pilot scale can thus be tested and evaluated on an industrial scale.