Designing Anion-Derived Solid Electrolyte Interphase in a Siloxane-Based Electrolyte for Lithium-Metal Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Electrolyte design is crucial for regulating the solid electrolyte interphase (SEI) in lithium-metal batteries.
• Weakly solvating electrolytes are effective for improving SEI properties and battery performance.

Purpose of the Study:

• To develop a novel siloxane-based weakly solvating electrolyte (SiBE) for lithium-metal batteries.
• To investigate the impact of SiBE on lithium deposition, SEI formation, and overall battery stability.

Main Methods:

• Formulation of a siloxane-based weakly solvating electrolyte (SiBE).
• Electrochemical testing of SiBE in lithium-metal cells, including Li||LiFePO4 full cells.
• Analysis of the solid electrolyte interphase (SEI) composition and properties.

Main Results:

• SiBE promotes dendrite-free lithium deposition and enhances cycle stability.
• The electrolyte facilitates the formation of a stable, Li+-conductive, inorganic anion-derived SEI.
• Li||LiFePO4 cells demonstrated 76.9% capacity retention after 1000 cycles at 2C.
• Limited Li-metal anode cells maintained 80% capacity retention over 110 cycles with 99.8% Coulombic efficiency.

Conclusions:

• Siloxane is a promising solvent for creating weakly solvating electrolytes.
• SiBE offers a new strategy for regulating SEI composition and improving lithium-metal battery performance.
• The developed electrolyte enables stable cycling and efficient lithium deposition.