Unlocking the potential of sustainable and solvent-free fabrication of electrodes for Li-ion battery cells

The main goal of UltraDry is to make the production of Li-ion batteries (LIBs) more sustainable. The last decades have seen an enormous increase in LIB use, and the demand is expected to increase significantly due to the key role of batteries within the green transition. With this increasing demand, the sustainability of the LIB production process must be addressed. UltraDry is targeting two aspects of today’s battery production that can improve sustainability: dry processing of battery electrodes and lowering the batteries’ fluorine content. Today, LIB electrodes are produced by mixing the battery materials in a solvent to form a slurry which is deposited on a metal foil, followed by drying step to remove the solvent. This drying process is very energy demanding and requires more than 30% of the total energy needed in battery production. Also, the solvent typically used for the cathode production is harmful, giving additional HSE concerns and raising cost of production. As an alternative, dry processing has recently attracted attention as a more sustainable fabrication method. Dry processing is potentially energy- and cost-effective, and can produce thicker electrodes with higher energy, but multiple challenges need to be solved before the process can be used industrially. In UltraDry we aim at filling some of the most critical knowledge gaps. In addition to relying on solvents during fabrication, today’s LIBs contain Li-salts with a high fluorine content in the electrolyte, typically LiPF6. The fluorine containing salts are often expensive, toxic, sensitive to water and can lead to formation of very harmful HF-gas inside the battery. UltraDry aims to develop new salts, with no or reduced fluorine content, which can increase the batteries’ sustainability and simplify battery recycling. UltraDry is a European m-era.net research project with SINTEF as coordinator and FREYR (Norway), IREC (Spain), and Warsaw University of Technology (Polen) as partners.

The overall goal of ULTRADRY is to improve the sustainability of battery production. This will be achieved by developing fundamental understanding about of dry processing of Li-ion battery (LIB) electrodes and reducing the F-content in the binder and electrolyte. The conventional way of preparing battery electrodes is by wet slurry casting, where the electrode materials are mixed in a solvent and cast on the current collector. The drying of this wet slurry is energy consuming and complex, and harmful solvents like N-methylpyrrolidone (NMP) are often used for cathodes, causing HSE concerns. Studies have shown that the wet slurry casting, drying and solvent recovery processes account for approximately half of the energy needed for battery production. Dry processing has the potential to overcome many of the limitations of wet-slurry casting, but several needs must still be addressed. ULTRADRY will contribute to this by combining several complementary activities, ranging from fundamental to applied, directly linked to improving sustainability. This includes: 1) Developing the fundamental knowledge about binder fibrillation mechanisms, which is lacking in the scientific literature. 2) Investigate the interlink between the process parameters during the different dry process steps, the achieved microstructure of the electrodes, and their mechanical and electrochemical performance. 3) Improve the sustainability of the battery electrolyte by developing new Li-salts as potential substitutes for the state-of-the-art LiPF6. 4) The most promising results, materials and components from these aforementioned activities will be assembled, tested and benchmarked against conventional batteries. This will be performed on a lab-scale, and with demonstration in a pilot line at the final year of ULTRADRY. 5) LCA, sustainability and techno-economic analyses is included as an integral part of ULTRADRY.