Magnesium Sulphide As Anode Material for Lithium-Ion Batteries

There is a great interest for alternative high capacity, low voltage anode materials in Li ion batteries. In an attempt towards this we report the investigation of magnesium sulphide (MgS) as sustainable anode material for lithium-ion batteries. The theoretical reaction potential of MgS with lithium is 0.5 V. It has a theoretical specific capacity of 951 mAh g^-1 assuming the following reaction.

MgS + 2Li   --->   Li₂S + Mg

In addition, lithium can react with magnesium to form alloys of lithium by further increasing the theoretical capacity. The high capacity combined with low reaction potential makes MgS an interesting anode material for Li-ion batteries in principle. Hence we synthesized MgS-carbon nanocomposites and evaluated them as anode material for lithium-ion batteries. A possible lithiation and delithiation mechanism for MgS is proposed based on electrochemical and ex-situ XRD studies. The electrochemical reaction of MgS with lithium results in the formation of Li₂S and Mg, the as-formed Mg simultaneously reacts with lithium and forms Li_xMg alloy further contributing to the capacity. A stable reversible capacity of 530 mAh g^-1 was achieved after 100 cycles within the voltage window of 0.001 - 2.5 V (Figure 1). The compatibility of MgS anode was tested in full cell using lithium nickel manganese cobalt oxide (LNMC) and lithium iron phosphate (LFP) as cathodes.