The Design of Transition Metal Sulfide Cathodes for High-Performance Magnesium-Ion Batteries

Despite the widespread use of lithium-ion battery (LIB) technology, conventional LIB suffer from severe limitations (e.g., low energy density, flammable electrolytes) that have prompted much research interest for alternative battery technologies. To overcome the limitations of lithium-ion batteries, magnesium-ion batteries (MIBs) have been proposed as promising alternative energy storage devices, with advantages of high volumetric energy density, high safety, low cost, and environmental benignity. However, the high charge density of Mg²⁺ in MIBs leads to sluggish electrochemical kinetics, owing to the strong electrostatic interactions between the host material and Mg²⁺. To mitigate this problem, transition metal sulfides (TMS) have been proposed as a solution and intensively researched as cathodes in MIBs, given that the soft features of sulfur can weaken undesirable electrostatic interactions (the low charge density of sulfur and high theoretical capacity). Nevertheless, TMS suffer from large volume variation, poor electronic conductivity as well as detrimental side reactions that all lead to degraded cycling performance. To this end, many solutions have been proposed to resolve these issues.