An ultra-dilute Mg(TFSI)₂ based electrolyte enabling reversible Mg metal anode

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Magnesium (Mg) metal anodes face passivation issues in conventional electrolytes like Mg(TFSI)2 in DME, hindering rechargeable Mg battery development.
• Harmful side reactions and passivation layers impede the efficiency and lifespan of Mg metal anodes.

Purpose of the Study:

• To devise an innovative electrolyte system to overcome Mg anode passivation in rechargeable Mg batteries.
• To enhance the reversibility and cycling stability of Mg electrodes.

Main Methods:

• Formulation of an ultra-dilute electrolyte (0.02 M Mg(TFSI)2) using DME with 4-chlorobutyl methyl ether (CME) as a co-solvent.
• Investigation of Mg plating/stripping processes and interphase formation using electrochemical techniques.

Main Results:

• The novel DME/CME electrolyte effectively suppresses TFSI-derived byproducts and promotes a protective Cl-rich interphase.
• Mg electrodes exhibited stable cycling with low overpotential (70 mV at 0.1 mA cm-2).
• Reversible electrochemical operation was maintained for 400 hours at 2 mA cm-2.

Conclusions:

• The developed ultra-dilute electrolyte offers a promising solution for Mg anode passivation in rechargeable Mg batteries.
• This formulation opens new avenues for high-performance and long-lasting rechargeable magnesium battery systems.