Mg Plating in Nonethereal Electrolyte Solutions: Fact or Misconception?

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Rechargeable Mg metal batteries (RMMBs) offer high energy storage potential.
• Ether solvents are common in RMMB electrolytes but have limited anodic stability.
• Novel nonethereal electrolytes are explored, but Mg plating verification is often lacking.

Purpose of the Study:

• To provide an overview of Mg electrochemistry in ethereal and nonethereal electrolytes.
• To critically evaluate Mg plating/stripping reversibility in various solvent systems.
• To present a protocol for verifying Mg plating in novel electrolytes.

Main Methods:

• Comprehensive cyclic voltammetry (CV) studies.
• Analysis of Mg plating/stripping activity across diverse electrolyte systems.
• Experimental protocol for confirming Mg deposition.

Main Results:

• Only ethers, amines, and dialkylsulfones demonstrate reversible Mg plating/stripping.
• Nitriles, amides, carbonates, and phosphates rarely show true Mg plating, despite apparent CV responses.
• Lack of direct evidence for Mg deposits can lead to misinterpretation of electrochemical data.

Conclusions:

• Electrochemical reversibility in RMMB electrolytes does not automatically confirm Mg plating.
• Careful experimental validation is crucial for developing new Mg battery electrolytes.
• The presented protocol aids in accurately assessing Mg plating/stripping capabilities of novel electrolyte systems.