Sodium-ion batteries are receiving increasing attention as they offer a more sustainable and less critical energy storage solution than lithium-ion batteries. Furthermore, SIBs are considered a drop-in technology, paving the way for direct production in existing facilities and the application of the same characterisation techniques and equipment.
In our efforts to scale up to pilot-plant electrode and prototype pouch cell production, we processed 100-gram batches of in-house Na3V2(PO4)3/C cathode active material into cathodes, and used commercial hard carbon to manufacture matching anodes. Carbonaceous solvents were used as the basis to develop the electrolyte.
Our findings from half-cell measurements focus on the high reactivity of elemental sodium and our approach to achieving reliable half-cell measurements, particularly for hard carbon, which is very challenging in simple two-electrode coin cells. Unlike hard carbon anodes, cathodes can be characterised using simple coin cells. However, artefacts were observed when testing cathode half-cells using commercial sodium chips.
Furthermore, proper balancing and careful consideration of the overhang area play a much more important role in SIBs than in LIBs, due to the significant loss of sodium ions, and therefore of absolute capacity, during formation.
Our work focuses on carbonate-based electrolytes, both with and without additives. We provide insights into the respective considerations for half- and full cells. Finally, the water content is another aspect that must be carefully evaluated in SIBs.
Ultimately, we provide further insights into current full-cell development with regard to sodium plating.