Mg₂Sn alloy anode materials with high interfacial activity for chloride ion batteries

Magnesium has been regarded as an intriguing anode material for chloride ion batteries (CIB) because of its abundant resources, multi-electron reaction feature, and high volumetric capacity. However, the passivation of magnesium in the electrolyte and formation of insulating MgCl₂ discharge product lead to poor reaction activity of magnesium anode in CIBs. Herein, the Mg₂Sn alloy prepared by mechanical alloying of magnesium and tin powders is first developed as the anode material with enhanced interfacial activity in the CIB using a metal chloride cathode. The cathode exhibits a significant increase in the discharge capacity from 82 to 175 mAh g⁻¹ when an Mg/carbon anode was replaced by the Mg₂Sn alloy anode. The discharge capacity can be further increased to more than 200 mAh g⁻¹ when the graphene nanoplatelet is incorporated in the Mg₂Sn alloy by mechanical milling, thus demonstrating the highly active alloy anode for chloride ion storage. This strategy also benefits the improvement in the cycling performance of the magnesium anode.