Lithium diffusion in spinel Li4Ti5O12 and LiTi2O4 compounds for future battery applications has been studied with muon spin relaxation (μ+SR). Measurements were performed on both thin-film and powder samples in the temperature range between 25 and 500 K. For Li4Ti5O12 and above about ∼200K, the field distribution width (Δ) is found to decrease gradually, while the field fluctuation rate (ν) increases exponentially with temperature. For LiTi2O4, on the contrary, the Δ(T) curve shows a steplike decrease at ∼350K, around which the ν(T) curve exhibits a local maximum. These behaviors suggest that Li+ starts to diffuse above around 200 K for both spinels. Assuming a jump diffusion of Li+ at the tetrahedral 8a site to the vacant octahedral 16c site, diffusion coefficients of Li+ at 300 K in the film samples are estimated as (3.2±0.8)×10-11 cm2/s for Li4Ti5O12 and (3.6±1.1)×10-11 cm2/s for LiTi2O4. Further, some small differences are found in both thermal activation energies and Li-ion diffusion coefficients between the powder and thin-film samples.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2015 Jul 20|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics