Reversible Mg-Metal Batteries Enabled by a Ga-Rich Protective Layer through One-Step Interface Engineering

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Magnesium-metal batteries (MMBs) face challenges due to native oxide layer formation on Mg-metal interfaces.
• This oxide layer hinders the use of conventional, non-toxic electrolytes in MMBs.

Purpose of the Study:

• To develop a simple and effective method for reversible MMB operation using a Mg(TFSI)₂-diglyme electrolyte.
• To create a Gallium-rich protective layer on Mg metal (GPL@Mg) to prevent native oxide formation.

Main Methods:

• Galvanic replacement reaction between Mg metal and a Gallium chloride (GaCl₃) solution.
• Characterization of the protective layer using various analytical tools.
• Electrochemical testing of MMBs with the modified Mg anode.

Main Results:

• A stable, ion-conducting Gallium-rich protective film (GPL@Mg) was successfully formed on the Mg metal surface.
• The protective layer prevented the formation of the native insulating oxide layer.
• Reduced polarization during Mg plating and stripping was observed in the diglyme-based electrolyte.
• Stable cycling of MMBs was achieved for over 200 hours.

Conclusions:

• The one-step process for creating GPL@Mg offers a cost-effective approach for modifying Mg-metal surfaces.
• The artificial protective layer is crucial for advancing the practical application of MMBs.
• This method provides insights into developing ion-conducting artificial layers for enhanced battery performance.