Production of Sodium-Ion Batteries in Baden-Württemberg

The PRONTO research project is developing scalable production processes, cell architectures, and active materials for sodium-ion batteries (SIB) with the aim of establishing battery cell production in Baden-Württemberg. The consortium, consisting of Fraunhofer ISE, KIT, and the University of Stuttgart, is supported by associated industry partners.

Initial Situation

The successes of lithium-ion technology show potential for electrification, but also entail supply chain risks due to critical raw materials such as lithium and cobalt. Sodium-ion batteries offer an attractive alternative thanks to lower raw material costs, good temperature stability, and high fast-charging capability, but currently have lower energy density. Conventional solvent-based coating processes incur high costs, energy consumption, and solvent recovery problems. There is therefore a need for environmentally friendly, cost-effective, and scalable production processes as well as optimized cell architectures for SIBs.

Objective

"PRONTO" aims to develop and demonstrate: (1) optimized anode and cathode active materials for SIBs; (2) a large-format, bipolar cell architecture; (3) a scalable dry-coating process for electrode production; (4) an overall concept for a production line, including a techno-economic assessment. The project intends to combine materials, modeling, and process technology in such a way that industrial production of SIBs in Baden-Württemberg becomes feasible.

Approach

Based on previous experience, Fraunhofer ISE is implementing an innovative, scalable PFAS-free dry-coating process for manufacturing electrodes that reduces drying costs, improves the environmental balance, and facilitates process integration. KIT is developing and synthesizing optimized active materials and electrolytes; the University of Stuttgart is providing models for cell optimization and design parameters for application-specific performance. At Fraunhofer ISE, both small test cells for material testing and large-format pouch cell formats are being realized using dry processing. At the same time, a production concept is designed and a techno-economic evaluation is carried out. The associated industry partners advise on industry-oriented implementation and provide expertise in machine technology, system integration, and production infrastructure.

Results

The "PRONTO" project demonstrates scalable dry-coating processes for manufacturing electrodes that reduce drying costs and solvent consumption compared to conventional processes. Thanks to material innovations, PRONTO has developed hard carbons with specific capacities exceeding 300 mAh/g and sustainable layered oxide cathodes with initial capacities above 180 mAh/g. Optimized electrode structures achieve high active material contents and thick electrodes of up to 900 µm, enabling areal capacities up to 10 mAh/cm² and energy densities above 130 Wh/kg in prototype pouch cells.

The modeling activities of the University of Stuttgart support the iterative design of electrodes, with a focus on porosity, layer thickness, and particle size, as well as operational parameters. Advanced dry-coating and granulation processes allow for scalable, PFAS-free electrode production with material cost potential significantly below 50 €/kWh, and with further optimization potentially down to 20 €/kWh. The developed cell architecture is modular and recyclable, supporting future industrial production and circular economy.

The effectiveness of these materials and processes is demonstrated in both small test cells and large-format prototypes. In cycle tests, competitive capacity retention has been achieved, and some advanced active materials show over 80% retention even after thousands of cycles. A production line concept and techno-economic evaluation have been developed, and feasibility studies with industry partners are paving the way for sodium-ion battery production in Baden-Württemberg.