High Voltage Magnesium-ion Battery Enabled by Nanocluster Mg₃Bi₂ Alloy Anode in Noncorrosive Electrolyte

Currently, developing high voltage (beyond 2 V) rechargeable Mg-ion batteries still remains a great challenge owing to the limit of corrosive electrolyte and low compatibility of anode material. Here we report a facile one step solid state alloying route to synthesize nanoclustered Mg₃Bi₂ alloy as a high-performance anode to build up a 2 V Mg-ion battery using noncorrosive electrolyte. The fabricated nanoclustered Mg₃Bi₂ anode delivers a high reversible specific capacity (360 mAh g^-1) with excellent stability (90.7% capacity retention over 200 cycles) and high Coulombic efficiency (average 98%) at 0.1 A g^-1. The good performance is attributed to the stable nanostructures, which effectively accommodate the reversible Mg²⁺ ion insertion/deinsertion without losing electric contact among clusters. Significantly, the nanoclustered Mg₃Bi₂ anode can be coupled with high voltage cathode Prussian Blue to assemble a full cell using noncorrosive electrolyte, showing a stable cycling (88% capacity retention over 200 cycles at 0.2 A g^-1) and good rate capability (103 mAh g^-1 at 0.1 A g^-1 and 58 mAh g^-1 at 2 A g^-1). The energy and power density of the as-fabricated full cell can reach up to 81 Wh kg^-1 and 2850 W kg^-1, respectively, which are both the highest values among the reported Mg-ion batteries using noncorrosive electrolytes. This study demonstrates a cost-effective route to fabricate stable and high voltage rechargeable Mg-ion battery potentially for grid-scale energy storage.