Lithium Self-Diffusion in a Polymer Electrolyte for Solid-State Batteries: ToF-SIMS/ssNMR Correlative...

Area of Science:

• Materials Science
• Electrochemistry
• Analytical Chemistry

Background:

• Solid-state electrolytes offer safer, higher energy density batteries by enabling lithium metal anodes.
• Understanding lithium ion transport is crucial for optimizing solid-state lithium metal battery performance.
• Lithium isotopic tracing is a powerful tool for elucidating ion transport mechanisms.

Purpose of the Study:

• To validate and apply complementary techniques, Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and solid-state Nuclear Magnetic Resonance (ssNMR) spectroscopy, for lithium isotopic analysis.
• To characterize lithium self-diffusion in polymer-based solid-state electrolytes.
• To establish robust methodologies for analyzing lithium transport in advanced battery materials.

Main Methods:

• Preparation of poly(ethylene oxide) (PEO) membranes with varying 6Li isotopic enrichments.
• Validation of ToF-SIMS and 6/7Li ssNMR spectroscopy for accurate lithium isotopic abundance determination.
• Application of validated methods combined with numerical simulations to determine lithium self-diffusion coefficients.

Main Results:

• Converging results from ToF-SIMS and ssNMR validated the methodologies with high accuracy (1-2% uncertainty).
• Lithium self-diffusion coefficient in a PEO-based membrane was determined to be 1.6 × 10^-12 m^2·s^-1 at 60 °C.
• The study successfully characterized lithium self-diffusion in a polymer electrolyte using isotopic tracing.

Conclusions:

• Validated ToF-SIMS and ssNMR are reliable tools for precise lithium isotopic analysis in battery materials.
• The established methodologies provide powerful strategies for understanding lithium ionic transport in solid-state electrolytes.
• This work contributes to the development of safer and more efficient solid-state lithium metal batteries.