Li tracer self-diffusion was studied in amorphous lithium−silicon compounds which are important as negative electrodes in Li-ion batteries. Experiments were done on Li x Si/ 6 Li x Si (Li x Si, x ∼ 0.02 and x ∼ 0.06) thin-film heterostructures using secondary ion mass spectrometry. The diffusivities follow the Arrhenius law in the temperature range between 140 and 325 °C, both with an activation energy of (1.42 ± 0.03) eV, while the Li-richer samples show 1 order of magnitude higher diffusivities. A trap-limited diffusion mechanism is suggested, explaining this result with a lower concentration of unsaturated traps. A discussion against the literature suggests a strong lithium concentration dependence of diffusivities also for higher x.

The present Letter reports on self-diffusion in amorphous silicon. Experiments were done on ^{29}Si/^{nat}Si heterostructures using neutron reflectometry and secondary ion mass spectrometry. The diffusivities follow the Arrhenius law in the temperature range between 550 and 700 °C with an activation energy of (4.4±0.3)  eV. In comparison with single crystalline silicon the diffusivities are tremendously higher by 5 orders of magnitude at about 700 °C, which can be interpreted as the consequence of a high diffusion entropy.

Amorphous lithium-silicon compounds are promising materials in order to improve pure silicon as a high-capacity anode material in lithium-ion batteries. We demonstrated that it is possible to produce amorphous Li x Si (x z 0.4) thin films by reactive ion-beam cosputtering of a segmented solid state target composed of metallic lithium and elemental silicon. At the surface a graded Li x SiO y layer of some nanometer thickness is formed by contact with air which seems to prevent decomposition of the Li x Si.

This article reports on Li self-diffusion in lithium containing metal oxide compounds. Case studies on LiNbO 3 , Li 3 NbO 4 , LiTaO 3 , LiAlO 2 , and LiGaO 2 are presented. The focus is on slow diffusion processes on the nanometer scale investigated by macroscopic tracer methods (secondary ion mass spectrometry, neutron reflectometry) and microscopic methods (nuclear magnetic resonance spectroscopy, conductivity spectroscopy) in comparison. Special focus is on the influence of structural disorder on diffusion.