Magnesium/Lithium Hybrid Batteries Based on SnS2-MoS2 with Reversible Conversion Reactions

The magnesium/lithium hybrid batteries (MLHBs) featuring dendrite-less deposition with Mg anode and Li-storage cathode are a promising alternative to Li-ion batteries for large-scale energy storage. However, their limited energy density limits their practical implementation. To improve this, beyond the commonly proposed intercalation compounds, high-capacity conversion-type cathodes based on heterostructures of tin sulphide-molybdenum disulphide (SnS2-MoS2) are proposed in this work. Individual SnS2 is already a promising high-capacity electrode material for multivalent batteries and undergoes conversion reactions during the ion storage process. The introduction of S-deficient MoS2 enhances the reversibility of SnS2 in the conversion reaction via strong polysulfide anchoring and catalytic effect. Our results show that the SnS2-MoS2 electrode achieves a high charge capacity of similar to 600 mAhg(-1) at 50mAg(-1) and an excellent rate capability of 240mAhg(-1) at 1000mAhg(-1) with a negligible capacity fading rate of 0.063% per cycle across 1000 cycles. The results highlight a new direction toward designing 2D heterostructures as high-capacity cathodes beyond intercalation-type cathodes for multivalent-ion batteries.