Phase-Structure Modulated Self-Supporting Indium-Bismuth Alloy Films as Anodes for Advanced Magnesium Ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Alloy-type anodes offer high theoretical capacity for magnesium ion batteries (MIBs).
• Key challenges include slow ion kinetics and significant volume changes during cycling.
• Developing stable and efficient anodes is crucial for advancing MIB technology.

Purpose of the Study:

• To engineer a self-supporting In-Bi alloy film anode for MIBs.
• To enhance the electrochemical performance of alloy-type anodes.
• To investigate the magnesium storage mechanism in the In-Bi system.

Main Methods:

• Fabrication of a biphase In-Bi/Bi film using magnetron sputtering.
• Electrochemical testing including rate capability and cycling performance evaluation.
• Operando X-ray diffraction to elucidate the (de)magnesiation mechanism.

Main Results:

• The biphase InBi/Bi electrode exhibited superior rate and cycling stability compared to single-phase In and Bi.
• Discharge capacities of 303.1 mAh g^-1 (550 cycles at 200 mA g^-1) and 292.6 mAh g^-1 (500 cycles at 2000 mA g^-1) were achieved.
• The two-phase structure effectively managed volume expansion and facilitated Mg²⁺ transport.

Conclusions:

• Phase-structure modulation via a biphase InBi/Bi film is an effective strategy for improving MIB anode performance.
• The enhanced performance is attributed to the synergistic effects of the two-phase configuration and increased phase boundaries.
• Operando XRD confirmed the (de)magnesiation mechanism, providing fundamental insights into Mg²⁺ storage in this alloy system.