Li-ion diffusion in Li intercalated graphite C₆Li and C₁₂Li probed by μ⁺SR

Area of Science:

• Materials Science
• Solid-State Physics
• Electrochemistry

Background:

• Understanding lithium-ion diffusion in graphite is crucial for Li-ion battery performance.
• Lithium-intercalated graphite compounds (e.g., C6Li, C12Li) are key anode materials.

Purpose of the Study:

• To investigate the diffusive behavior of Li+ in Li-intercalated graphite (C6Li and C12Li).
• To determine the activation energy and diffusion coefficients for Li+ in these materials.

Main Methods:

• Muon spin relaxation (μ+SR) spectroscopy was employed.
• Measurements were performed on electrochemically synthesized C6Li and C12Li samples.
• Analysis focused on the temperature-dependent diffusive behavior of Li+.

Main Results:

• Li+ ions exhibit diffusive behavior above 230 K in both C6Li and C12Li.
• The diffusion process follows a thermal activation mechanism.
• Activation energies were determined: Ea = 270(5) meV for C6Li and Ea = 170(20) meV for C12Li.
• Self-diffusion coefficients at 310 K were estimated: DLi = 7.6(3) × 10^-11 cm²/s (C6Li) and DLi = 14.6(4) × 10^-11 cm²/s (C12Li).

Conclusions:

• The study provides quantitative insights into Li+ diffusion dynamics in graphite intercalation compounds.
• The findings suggest that C12Li offers potentially faster Li+ transport compared to C6Li.
• Muon spin relaxation is a valuable technique for probing ion diffusion in battery materials.