Li-ion batteries have major disadvantages. One of which is the growth of dendrites (in case Li metal based batteries), a major safety issue. In addition to that, Li-ion batteries also use elements such as Co, and Li, which are regionally scarce. Mg-ion batteries are one of the alternatives for Li-ion batteries. However, the electrolyte and cathode materials for Mg-ion batteries, are still in developmental stages.
In this study, the use of a sulphur-based spinel (also known as thiospinel) material as a cathode is explored. After literature review, MgMn2S4 and MgTi2S4 were identified as suitable cathode materials. Following which, the MgMn2S4 spinel is doped with Ti in the place of Mn at different doping ratios and the resulting combinations are evaluated for their stability, average intercalation voltage, volume change, spinel inversion and migration barriers. Two combinations MgMnTiS4 and MgMn0.75Ti1.25S4 are found to be stable with respect to the end members i.e. MgMn2S4 and MgTi2S4. Average voltages of 1.702 and 1.527 V (vs. Mg/Mg2+) are observed for MgMnTiS4 and MgMn0.75Ti1.25S4. However, spinel inversion is observed in MgMnTiS4. A volume change of 21.2, and 20% is observed in MgMnTiS4 and MgMn0.75Ti1.25S4, respectively. ... Read more