Computational modelling on the stability of solid electrolytes in magnesium-ion batteries

Abstract

Developing new battery technologies to sustain the ever-growing demand for energy storage constitutes one of the greatest scientific and societal challenges of the century. Lithium-ion batteries (LIBs) are frequently used at the moment as energy storage, and they are used to power millions of portables electronics, electric vehicles, and are even seeing introduction into the electric grid. But LIBs are facing some challenges such as safety, durability, uniformity and cost. A technology that has the potential to alleviate resource issues with Li-ion systems and further increase the energy density is Mg2+ intercalation systems. Replacing Li with safer and earth-abundant Mg has the advantage of doubling the total charge per ion, which result in larger theoretical volumetric capacity compared with LIB. First principle based calculations were used to investigate the stability of discharge products of solid electrolytes in the magnesium-ion battery. We found that MgSc2S4 and MgSc2Se4 structures are stable semi-conductors due to the band gap observed in the density of states. No negative vibrational frequencies are observed along all direction in the phonon dispersion curves which indicate stability. The calculated elastic constants indicate that the structures are mechanically stable. The results of this paper aimed to give an insight into the stability of solid electrolytes and to provide inspiration for future research in magnesium-ion batteries.