Tailoring Coordination in Conventional Ether-Based Electrolytes for Reversible Magnesium-Metal Anodes

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Rechargeable magnesium batteries face challenges with ion-blocking passivation layers on the magnesium metal anode, hindering performance.
• Understanding the Mg2+ solvation sheath is crucial for addressing these passivation issues in conventional electrolytes.

Purpose of the Study:

• To investigate the link between Mg2+ solvation coordination and passivation layer formation in magnesium batteries.
• To develop a strategy for tailoring solvation coordination to improve Mg metal anode stability and battery cycling performance.

Main Methods:

• Tracking the Mg2+ solvation sheath dynamics using spectroscopic or computational methods.
• Introducing additive solvents with high electron richness, specifically organophosphorus compounds.
• Analyzing the decomposition products of additive solvents on the Mg surface and their effect on Mg2+ transport.

Main Results:

• Additive solvents with electron-rich phosphorus-oxygen groups compete with DME for Mg2+ coordination, softening the solvation sheath.
• Organophosphorus molecules in the rearranged sheath decompose on the Mg surface, enhancing Mg2+ transport and electrical resistance.
• Symmetric cells demonstrated superior cycling performance exceeding 600 cycles with reduced polarization.

Conclusions:

• Tailoring Mg2+ solvation coordination through additive solvents is an effective strategy to mitigate passivation layer issues in rechargeable magnesium batteries.
• The proposed method enhances Mg2+ transport and stability, leading to significantly improved battery cycling performance and longevity.