Unveiling the electronic properties of native solid electrolyte interphase layers on Mg metal electrodes using local...

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Magnesium-ion batteries (MIBs) offer a sustainable, safe, and cost-effective alternative to lithium-ion systems.
• Spontaneous electrolyte decomposition forms native solid electrolyte interphases (n-SEIs) on Mg anodes, hindering charge transfer and limiting MIB performance.
• Understanding n-SEI properties is critical for advancing MIB technology.

Purpose of the Study:

• To employ scanning electrochemical microscopy (SECM) for local quantification of n-SEI electronic properties in MIBs.
• To investigate the impact of different electrolyte formulations (organoaluminate, organoborate, TFSI-based) on n-SEI formation and characteristics.
• To correlate n-SEI properties with their chemical composition and morphology.

Main Methods:

• Utilized scanning electrochemical microscopy (SECM) to probe the local electronic conductivity of n-SEIs.
• Formed n-SEIs by contacting Mg metal with various electrolyte solutions (organoaluminate, organoborate, TFSI-based).
• Performed ex situ morphological and chemical characterization (e.g., SEM, EDX) to complement SECM findings.

Main Results:

• TFSI-based electrolytes formed n-SEIs with high electronic and ionic insulating properties.
• Organoaluminate electrolytes resulted in n-SEIs with low electronic protection.
• Organoborate electrolytes yielded n-SEIs with intermediate properties between TFSI and organoaluminate.
• Observed a strong correlation between n-SEI chemical composition and its electronic/ionic conductivity.

Conclusions:

• SECM is an effective tool for characterizing n-SEIs in MIBs.
• Electrolyte selection significantly influences n-SEI properties, impacting MIB performance.
• Tailoring electrolyte composition allows for control over n-SEI characteristics, paving the way for improved MIBs.