Solvent-Free Mechanochemical Approach towards Thiospinel MgCr2S4 as a Potential Electrode for Post-Lithium Ion Batteries

Laura Caggiu,Gabriele Mulas,Sebastiano Garroni,Lorenzo Stievano,Claudio Gerbaldi,Stefano Enzo,Marisa Falco,Romain Berthelot

doi:10.3390/batteries6030043

Abstract

Several new compounds, with desirable properties of ion mobility and working voltage, have been recently proposed using a density functional theory (DFT) computational approach as potential electrode materials for beyond-lithium battery systems. After evaluation of the ‘energy above hull’, thiospinel MgCr2S4 has been suggested as interesting multivalent battery cathode candidate, even though the synthesis of its exact stoichiometry poses serious challenges. In this work, MgCr2S4 is prepared using an innovative mechanochemical route starting from magnesium or magnesium hydride, chromium, and sulfur powders. The progress of such mechanically induced reaction as a function of processing time is carefully monitored by XRD with Rietveld refinement, evidencing the occurrence of a mechanically induced self-propagating reaction (MSR). The effect of parameters associated with the milling apparatus (impact energy) on the products composition are also investigated. To our knowledge, this work represents the first report of the scalable and simple mechanical alloying synthesis of thiospinel MgCr2S4 (space group Fd-3 m, a = 10.09 Å) and opens up interesting possibilities for the exploitation of such material in next-generation post-lithium batteries.

Highlights

In the framework of the increasingly high demand for electrical energy storage (EES) systems [1,2], smart grid, and stationary power networks, particular attention is focused on secondary batteries.For this reason, materials viable for these applications are the epicenter of many studies, including new computational compounds with theoretically suitable electrochemical characteristics [3]
The mechanochemical synthesis of the thiospinel MgCr2 S4 has been approached by using a SPEX
The mechanical processing was characterized by a rapid increase of the vial temperature, which is a clear evidence of the ignition step in the mechanically induced self-sustaining reaction (MSR) reactions

Summary

Introduction

In the framework of the increasingly high demand for electrical energy storage (EES) systems [1,2], smart grid, and stationary power networks, particular attention is focused on secondary batteries.For this reason, materials viable for these applications are the epicenter of many studies, including new computational compounds with theoretically suitable electrochemical characteristics [3]. In the framework of the increasingly high demand for electrical energy storage (EES) systems [1,2], smart grid, and stationary power networks, particular attention is focused on secondary batteries. In 2016, LIB market reached over US $20 billion, US $5 billion of which for the automotive industry [6]. This growing market will drive the increase of lithium demand, and most likely its price, since lithium is becoming a critical element, due to its limited availability and often problematic supply chain [7].

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Results

Conclusion