Yolk-Shell Structured ST@Al₂ O₃ Enables Functional PE Separator with Enhanced Lewis Acid Sites for High-Performance...

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Commercial polymer separators suffer from low porosity, poor electrolyte wettability, and inadequate thermal/mechanical stability, limiting battery performance, especially at high current densities.
• These limitations hinder the efficiency and lifespan of energy storage devices.

Purpose of the Study:

• To develop a functional polyethylene (PE) separator with enhanced properties for improved battery performance.
• To address the limitations of conventional separators by incorporating a novel surface engineering approach.

Main Methods:

• Surface engineering of a polyethylene (PE) separator with Ti-doped SiO2@Al2O3 particles (ST@Al2O3-PE).
• The ST@Al2O3 particles possess strong Lewis acid properties and a uniform porous structure.
• Characterization of the separator's porosity, electrolyte wettability, ionic conductivity, and lithium-ion transport properties.

Main Results:

• The ST@Al2O3-PE separator exhibits enhanced ionic conductivity (5.55 mS cm⁻¹) and a higher lithium-ion transference number (0.62).
• ST@Al2O3 particles provide abundant electrolyte storage and shorten ion transport pathways.
• Stabilized lithium metal anode performance with tunable Li plating/stripping behavior.
• Li/Li symmetric cells achieved stable cycling over 400 hours at 1 mA cm⁻².
• Improved cycling and rate performance in lithium iron phosphate/Li and lithium cobaltate/Li cells.

Conclusions:

• The developed ST@Al2O3-PE functional separator offers a promising strategy for advancing lithium metal battery technology.
• Surface engineering with ST@Al2O3 particles significantly enhances separator properties, leading to superior battery performance and stability.
• This approach paves the way for the commercialization of high-performance lithium metal batteries.