Compact Solid Electrolyte Interface Realization Employing Surface-Modified Fillers for Long-Lasting, High-Performance...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Polymer-based lithium-metal batteries face challenges with low coulombic efficiency and poor cycling stability due to electrolyte decomposition.
• Improving the stability of the solid electrolyte interface (SEI) is crucial for mitigating this decomposition and enhancing battery performance.

Purpose of the Study:

• To develop a novel composite polymer electrolyte (MSMB-CPE) using surface-functionalized silica mesoball fillers.
• To investigate the impact of these fillers on the SEI stability, ionic conductivity, and overall performance of lithium-metal batteries.

Main Methods:

• Fabrication of composite polymer electrolyte (MSMB-CPE) with surface-functionalized silica mesoball fillers.
• Molecular dynamics simulations to study ion dissociation energy and filler-electrolyte interactions.
• Electrochemical testing including ionic conductivity, transference number, symmetric cell performance, and full cell cycling.

Main Results:

• Surface modification ensures uniform filler distribution, providing large surface area and Lewis acid sites.
• Simulations show a fourfold higher dissociation energy of LiTFSI in the filler compared to filler-free electrolytes.
• MSMB-CPE exhibits 30 times higher diffusivity, ionic conductivity of 1.16 × 10⁻² S cm⁻¹ at 60 °C, and a Li-ion transference number of 0.81.
• Stable symmetric cell performance for over 5000 h at high current density (200 µA cm⁻² @60 °C).
• 85.60% capacity retention in a [Li/MSMB-CPE/LiFePO₄] full cell after 700 cycles.
• Compositional analysis reveals a smooth SEI layer with fewer by-products.

Conclusions:

• Surface-functionalized silica mesoball fillers effectively enhance SEI stability in polymer electrolytes.
• The developed MSMB-CPE offers significantly improved ionic conductivity, ion transport, and cycling stability for lithium-metal batteries.
• This approach presents a promising strategy for developing high-performance and stable polymer-based lithium-metal batteries.