Speaker
Description
Magnesium-ion batteries are a promising energy storage technology of our time due to their higher theoretical energy density and low raw materials. Now among the major setbacks has been the identification of cathode materials that will demonstrate capacities and voltages identical to lithium-ion systems. Then, in this study, we make use of first-principle based calculations to study the stability of the discharge products MgSc2S4, MgSc2Se4, MgY2S4, MgY2Se4, MgIn2S4, and MgIn2Se4 whereby we investigate their structural properties, mechanical properties, electronic properties, and their phase stability. The computational technique was employed utilising the ab initio density functional theory (DFT) through the Vienna Ab initio Simulation Package (VASP) code within the generalised gradient approximation (GGA) in the form of Perdew-Burke-Ernzerhof (PBE) exchange-correlation. It was found from the heats of formation that all structures are stable. The calculated elastic constants show that the structures are mechanical stable with the C’ value being positive which is in good agreement with the phonon dispersion curves. The total density of states (tDOS) shows that all the structures are semi-conductors due to the presence of direct band gaps. Phonon dispersion curves show that the structures are vibrational stable due to no soft modes observed along the gamma region. After all these findings, we then made use of the Universal Cluster Expansion (UNCLE) code, which is a machine learning code. We added Selenium (Se) to Sulphur (S) since Se has the advantage of prolonging the lifespan of S. It is found that MgSc2S1-xSex, MgY2S1-xSex, and MgIn2S1-xSex systems, generated 97, 61, and 12 new mixed phases, respectively. Now the results found in this study aimed to give an insight into the stability of solid electrolytes and in order to provide inspiration for future research in magnesium-ion batteries.
