Lithium Sulfide: Magnesothermal Synthesis and Battery Applications

As a critical material for emerging lithium–sulfur batteries and sulfide-electrolyte-based all-solid-state batteries, lithium sulfide (Li2S) has great application prospects in the field of energy storage and conversion. However, commercial Li2S is expensive and is produced via a carbon-emissive and time-consuming method of reducing lithium sulfate with carbon materials at high temperatures. Herein we report a novel method of synthesizing Li2S by thermally reducing lithium sulfate with the first non-carbon-based reductant Mg. Compared with the commercial carbothermal method, our magnesothermal technique has multiple advantages, such as completion in minutes, operation at lower temperatures, emission of zero amount of greenhouse-gases, and a valuable byproduct MgO. Moreover, the prepared Li2S product demonstrates excellent cathode performance in lithium–sulfur batteries, in terms of cycling stability, activation voltage, and rate capability. Thus, this innovative method opens a new direction for the research of Li2S and has great potential for practical applications.