Synthesis and Characterization of MgCr₂S₄ Thiospinel as a Potential Magnesium Cathode

Abstract

Magnesium-ion batteries are a promising energy storage technology because of their higher theoretical energy density and lower cost of raw materials. Among the major challenges has been the identification of cathode materials that demonstrate capacities and voltages similar to lithium-ion systems. Thiospinels represent an attractive choice for new Mg-ion cathode materials owing to their interconnected diffusion pathways and demonstrated high cation mobility in numerous systems. Reported magnesium thiospinels, however, contain redox inactive metals such as scandium or indium, or have low voltages, such as MgTiS. This article describes the direct synthesis and structural and electrochemical characterization of MgCrS, a new thiospinel containing the redox active metal chromium and discusses its physical properties and potential as a magnesium battery cathode. However, as chromium(III) is quite stable against oxidation in sulfides, removing magnesium from the material remains a significant challenge. Early attempts at both chemical and electrochemical demagnesiation are discussed.

Selective metathesis synthesis of MgCr2S4 by control of thermodynamic driving forces

“…Following this prediction, Wustrow et al successfully synthesized MgCr2S4 through a traditional solid-state synthesis approach-although it was found to be a laborious reaction. 12 Starting from elemental (Mg + Cr + S) precursors, the binary sulfides, MgS and Cr2S3, formed rapidly upon heating. However, the subsequent reaction from MgS + Cr2S3 to ternary MgCr2S4 required holding at 800 °C for two weeks, with numerous intermediate regrinds.…”

Structural Peculiarities and Thermoelectric Study of Iron Indium Thiospinel

“…The spinel structure is known to be flexible and allows an accommodation of 1) a variety of metallic elements with different atomic size and mass, 2) ordered or disordered arrangement of cations (so‐called normal, inverse, or intermediate structures), and 3) partially occupied crystallographic positions. All these result in a diversity of magnetic, optical, catalytic, electrical, as well as thermoelectric (TE) properties . Many spinels consisting of well‐abundant and environmental‐friendly elements (which is crucial for a possible thermoelectric application) became the object of numerous studies.…”

Recent Progress on Layered Cathode Materials for Nonaqueous Rechargeable Magnesium Batteries

“…However, only a few materials, such as Chevrel phases, layered materials, Prussian blue analogues, spinel phases, organic materials, and polyanion compounds, have been reported to be feasible as hosts for Mg 2+ storage in RMBs. [23][24][25][26][27][28] Among these materials, layered materials have attracted extensive attention in recent years due to their relatively high capacity, simple structures, and facile synthesis process. [29][30][31][32] The crystal structures of layered materials are similar to that of graphite.…”