Dual-Layered Interfacial Evolution of Lithium Metal Anode: SEI Analysis via TOF-SIMS Technology

Area of Science:

• Materials Science
• Electrochemistry
• Analytical Chemistry

Background:

• Lithium metal batteries offer high energy density but suffer from unstable solid/liquid interfaces.
• The solid electrolyte interface (SEI) layer is crucial for anode stability but its structure is poorly understood.
• Accurate SEI characterization is vital for advancing next-generation energy storage.

Purpose of the Study:

• To investigate the chemical composition and structure of the SEI layer on lithium metal anodes.
• To utilize Time-of-flight secondary ion mass spectrometry (TOF-SIMS) for high-resolution nanoscale analysis of the SEI.
• To develop a more realistic model for the SEI layer in lithium metal batteries.

Main Methods:

• Electrochemical cycling of lithium metal anodes.
• Three-dimensional (3D) characterization using Time-of-flight secondary ion mass spectrometry (TOF-SIMS).
• Analysis of SEI chemical composition and lithium salt distribution.

Main Results:

• The SEI layer is not a completely dense interface.
• The organic phase of the SEI accommodates electrolyte, enhancing lithium-ion conductivity.
• TOF-SIMS can quantify SEI changes by analyzing lithium salt distribution, which is difficult with conventional methods.

Conclusions:

• TOF-SIMS is a powerful tool for detailed SEI characterization at the nanoscale.
• Understanding the SEI's non-dense and dynamic nature is key to improving lithium metal battery stability.
• This research provides guidance for accurate SEI modeling and enhanced battery performance.