Synergistic Cyclodextrin-LiTFSI Coating on LLZTO toward High Ionic Conductivity PVA-Based Composite Electrolytes

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Poly(vinyl alcohol) (PVA)-based composite electrolytes incorporating Li6.75La3Zr1.75Ta0.25O12 (LLZTO) show promise for lithium-ion batteries due to high ionic conductivity.
• Aggregation of LLZTO particles in PVA hinders lithium-ion transport, limiting electrolyte performance.

Purpose of the Study:

• To develop a surface modification strategy for LLZTO particles to improve their dispersion and compatibility within PVA-based electrolytes.
• To investigate the impact of cyclodextrin-LiTFSI (C-T) complex coating on LLZTO and its effect on the electrochemical properties of the composite electrolyte.

Main Methods:

• Surface coating of LLZTO nanoparticles with a cyclodextrin-LiTFSI complex (C-T).
• Fabrication of poly(vinyl alcohol)-ionic liquid-LLZTO@C-T (PIL@C-T) composite electrolytes with varying LLZTO@C-T content.
• Electrochemical characterization including ionic conductivity measurements and battery cycling performance evaluation.

Main Results:

• The PIL@C-T composite electrolyte achieved an ionic conductivity of 4 × 10^-3 S/cm at 60 wt% LLZTO content.
• The C-T coating effectively improved LLZTO dispersion in the PVA matrix and facilitated fast lithium-ion transport pathways.
• A LiFePO4 | PIL@C-T | Li battery demonstrated a discharge capacity of 162 mAh/g with stable cycling for 200 cycles.

Conclusions:

• The C-T coating is an effective strategy to enhance the compatibility between ceramic fillers and polymer matrices in composite electrolytes.
• The developed PIL@C-T composite electrolyte offers a promising pathway for high-performance lithium-ion batteries.
• This approach provides a new method for designing advanced composite electrolytes for energy storage applications.