Using a Chloride-Free Magnesium Battery Electrolyte to Form a Robust Anode-Electrolyte Nanointerface

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Magnesium bis(hexamethyldisilazide) (Mg(HMDS)2)-based electrolytes show promise for magnesium batteries.
• Chloride salts in these electrolytes cause corrosion and limit anodic stability.
• Developing chloride-free electrolytes is crucial for practical applications.

Purpose of the Study:

• To develop a chloride-free Mg(HMDS)2-based electrolyte for rechargeable magnesium batteries.
• To improve the electrochemical performance and component compatibility of magnesium electrolytes.
• To investigate the interfacial behavior of the magnesium anode in the new electrolyte.

Main Methods:

• Formulation of a chloride-free Mg(HMDS)2 electrolyte in 1,2-dimethoxyethane.
• Utilizing tetrabutylammonium borohydride to control moisture content.
• Electrochemical testing of magnesium plating/stripping and cathode compatibility.
• Surface analysis and depth profiling of the magnesium anode.

Main Results:

• The chloride-free electrolyte achieved an average Coulombic efficiency of 98.3% over 150 cycles for magnesium plating/stripping.
• The electrolyte demonstrated noncorrosive behavior towards cell components.
• A robust solid electrolyte interphase (SEI) formed on the magnesium anode, enabling reversible cycling.
• Good compatibility was observed with a copper sulfide cathode, yielding a high initial discharge capacity of 261.5 mAh g-1.

Conclusions:

• The developed chloride-free Mg(HMDS)2 electrolyte offers superior performance and stability for rechargeable magnesium batteries.
• The formation of a stable SEI layer is key to the reversible magnesium plating/stripping.
• This advancement paves the way for more practical and durable magnesium battery technologies.