Regulating Electric Double Layer via Self-Assembled Monolayer for Stable Solid/Electrolyte Interphase on Mg Metal...

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Stabilizing the solid electrolyte interphase (SEI) on magnesium anodes is crucial for rechargeable magnesium battery performance.
• Traditional methods often require high additive concentrations and complex electrolyte chemistry.
• The electric double layer (EDL) at the anode-electrolyte interface plays a key role in SEI formation but is understudied.

Purpose of the Study:

• To develop a novel self-assembled monolayer (SAM) strategy for modulating the cationic solvation structure and SEI formation.
• To investigate the use of (trifluoromethyl)trimethylsilane (TFTMS) as a low-concentration additive to enhance SEI stability.

Main Methods:

• Utilized (trifluoromethyl)trimethylsilane (TFTMS) at low concentrations (2 vol%) to form a self-assembled monolayer on the Mg anode.
• Investigated the dipole-dipole interactions between TFTMS and electrolyte solvent molecules.
• Analyzed the effect of TFTMS on solvent-Mg2+ coordination and anion-Mg2+ interaction.

Main Results:

• Achieved a stable, dense, and electronically insulating SEI layer through the SAM strategy.
• Enabled stable cycling of symmetric cells for over 1000 hours and reversible Mg plating/stripping at 5 mA cm−2.
• Demonstrated favorable compatibility with various cathode materials.

Conclusions:

• The SAM strategy using TFTMS is a simple and effective method to improve SEI stability in magnesium batteries.
• This approach enhances Mg anode reversibility and battery cycle life.
• The SAM strategy shows generality and potential for practical application in rechargeable magnesium batteries.