Inverse vulcanised sulphur as an electroactive material for lithium-sulphur and sodium-sulphur batteries

This thesis deals with the study of lithium-sulfur and sodium-sulfur batteries, which are designed for use at room temperatures. Both of these systems are interesting mainly due to their high theoretical capacity and low environmental impact, thus greatly outperforming lithium-ion batteries. The weakness of these new technologies is their low lifespan and the associated rapid loss of battery capacity. To increase the lifespan, elemental sulfur in this work was replaced by sulfur with an amorphous structure, synthesized by an inverse vulcanization process that has been optimized in various ways. In addition to the optimization of the inverse vulcanization technology window, the effect of the addition of carbonaceous additives during the synthesis was also investigated. In this work, a series of samples of inverse vulcanized sulfur with different ratios of input precursors were prepared and also with different additives. X-ray diffraction was used to confirm the amorphous structure of the material, which also excludes the presence of crystalline sulphur. The results of Raman spectroscopy were also presented, demonstrating the possibility of using this method to determine semi-quantitative ratios of the input precursors. Electrodes for electrochemical cells were fabricated from selected samples. The homogeneity of the distribution of the electroactive material on the electrode was investigated using a scanning electron microscope and elemental mapping by energy dispersive spectroscopy technique. The electrochemical characterization of the inversely vulcanized sulfur electrodes was carried out by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic potential limited cycling