Rechargeable batteries are of high current interest as a storage medium for electrical energy. Although lithium-ion batteries are state of the art today, alternatives are also being intensively evaluated. Sodium-ion batteries are currently being investigated as a promising candidate to replace Li-ion batteries due to the high availability of Na compared to Li, similar cell structure and ease of transport. However, only a few solvent systems have been described so far, mostly based on the current Li-ion electrolytes, which consist of carbonate-based solvent mixtures. It is necessary for an ideal electrolyte for sodium-based batteries to meet similar characteristics as Li-ion cells: low cost, electrochemical stability, chemical stability, non-toxicity, scalability, and thermal stability.
In the study, the electrolyte mixtures with selected classes of organic solvents were evaluated according to their physicochemical as well as electrochemical properties. The stability of the electrolyte formulations towards sodium metal were studied in detail by gas chromatography. The reactivity towards sodium is compared between mixtures with and without NaClO4 and the degradation products are analyzed by gas chromatography.