Exploiting a high-performance magnesium-fluoride battery prototype enabled by anion-receptor-mediated electrolyte.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Rechargeable magnesium batteries offer abundant resources and safety but lack high-performance positive electrodes, limiting specific energy.
• Developing advanced electrolytes is crucial for unlocking the potential of magnesium batteries.

Purpose of the Study:

• To design an anion-receptor-mediated electrolyte for magnesium batteries.
• To enable electrochemical cooperation between fluoride and magnesium for enhanced performance.

Main Methods:

• Anion receptor (tris(pentafluorophenyl)borane) mediated all-phenyl-complex electrolyte.
• Development of a Mg||FeO_0.7F_1.3 battery prototype.
• Analysis of electrolyte composition and solvation structures via dipole-ion and dipole-dipole interactions.

Main Results:

• Tailored electrolyte mitigated chloride-originated anodic instability and improved desolvation kinetics.
• Mg||FeO_0.7F_1.3 batteries demonstrated high reversible capacities (354 mAh g⁻¹ at 25°C, 177 mAh g⁻¹ at -20°C).
• High reversibility over 500 cycles with low capacity decay (0.054% per cycle) achieved via intercalation chemistry.

Conclusions:

• Anion receptor-based electrolyte design strategy expands positive material options for magnesium batteries.
• High-energy fluorides are viable positive electrode materials for magnesium batteries.
• The developed electrolyte enables dual-cation co-driven conversion-type batteries with excellent performance across temperatures.