SPRINT

The demand for technically robust and inexpensive energy storage devices is increasing worldwide. These devices store energy that is not needed at the moment for later use. Currently, the high demand is largely met by lithium-ion batteries, which, however, have some disadvantages. They are very expensive to manufacture and require critical raw materials that, in turn, are associated with geopolitical dependencies in terms of supply chains.

The sodium-ion battery offers a promising alternative to solve this problem. As a component of common salt (NaCl), sodium is significantly cheaper than lithium and is available worldwide in practically unlimited quantities. NaCl is the second largest component of seawater in terms of quantity, and both the extraction of sea salt and the mining of underground salt deposits have been established for centuries. This results in a cost advantage for the raw materials used in battery production and, in the long term, cheaper production than with lithium-ion technology. Sodium-ion batteries are therefore suitable for energy storage applications where weight is not an issue (e.g. storage power plants for wind and solar energy). However, as development progresses, mobile applications such as electric cars are also increasingly coming into focus. Furthermore, sodium-ion batteries offer faster charging times, which is an additional advantage compared to lithium-ion batteries.

The SPRINT project, funded by the European Union, aims to further develop the sodium-ion battery technology described above in order to make it commercially available for as many applications as possible. For this purpose, a total of 18 partners from industry and research across Europe are bundling their expertise.

SPRINT's approach focuses on the use of abundant, non-toxic materials originating in the EU to improve the safety, performance and scalability of batteries.

The following innovations for the further development of sodium-ion battery technology are being targeted:

• The production of optimized sodium iron phosphate materials (NFP) for cathodes using novel synthesis techniques
• Production of sustainable carbonaceous materials derived from a validated supply chain for forest residues in Northern Europe
  
• Use of solvent-free and dry manufacturing processes for better scalability and commercialization
• Use of quasi-solid polymer and composite electrolytes (a mixture of liquid and solid electrolytes) as a solvent-free alternative to flammable liquid electrolytes
• Integration of PFAS-free (per- and polyfluorinated alkyl substances) binders to improve sustainability in battery production
  

Fraunhofer IWKS is leading the way in the development of quasi-solid electrolytes and is also analysing the ecological impact of the entire manufacturing process using (social) life cycle assessment methods.

For practical demonstration purposes, test sites for developed sodium battery systems are being set up at two European locations as part of the project. In Austria, the batteries are to be tested specifically for use in the intermediate storage of electricity from public power grids (grid balancing service), while in Lithuania the focus is on their use as electricity storage in photovoltaic systems and on increasing grid capacity when charging electric vehicles. In addition, SPRINT is also working with non-European stakeholders in Morocco, Tunisia, Kenya and Sierra Leone to explore even broader application possibilities.

As a result of the research and development work carried out in this project, the following effects are expected:

1. Reduction of costs to 0.04 €/kWh and cycle
2. Improvement of energy density of batteries (> 200 Wh/kg & 420 Wh/L)
3. Improvement of power output (> 500 W/kg)
   
4. Increase in service life of the cells to an expected 5,000+ cycles
5. Guarantee of safe and leak-free operation as a prerequisite for high market penetration