Binary Mg-1 at%Gd alloy anode for high-performance rechargeable magnesium batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Rechargeable magnesium batteries (RMBs) are promising for large-scale energy storage due to magnesium's high capacity, safety, and abundance.
• Current challenges include uneven magnesium stripping and high overpotentials, leading to anode failure via pitting perforation.

Purpose of the Study:

• To develop a high-performance magnesium alloy anode for RMBs.
• To improve the uniformity and efficiency of magnesium plating and stripping.
• To enhance the cycling stability and lifespan of RMBs.

Main Methods:

• Fabrication of a binary Mg-1 at% Gd alloy anode using melting and hot extrusion.
• Electrochemical characterization to evaluate Mg plating/stripping behavior and overpotential.
• Assembly and testing of a full cell using the Mg-Gd anode and a Mo6S8 cathode.

Main Results:

• The Mg-Gd alloy significantly reduced the Mg2+ diffusion energy barrier to 0.34 eV.
• Formation of a robust, low-resistance electrolyte/anode interphase was observed.
• The Mg-Gd anode demonstrated an extended lifespan of 220 hours with low overpotential (213 mV) at 5.0 mA cm-2.
• The full cell achieved high rate performance (73.5 mAh g-1 at 5C) and 8000 cycles at 5C.

Conclusions:

• The addition of 1 at% Gd effectively enhances the electrochemical performance of Mg anodes in RMBs.
• The developed Mg-Gd alloy anode offers a pathway for practical and commercial RMB applications.
• This research provides insights into designing advanced Mg alloy anodes for next-generation energy storage systems.