Li Diffusion in Thin-Film Li<i><sub>y</sub></i>Si Electrodes: Galvanostatic Intermittent Titration Technique and Tracer Diffusion Experiments
Daniel Uxa, Erwin Hüger, Harald Schmidt
Abstract
LiySi is an interesting material for negative electrodes in Li-ion batteries. We carried out measurements with a galvanostatic intermittent titration technique (GITT) on ion-beam-sputtered amorphous LiySi (y ≈ 0.02 and 0.25) films to determine Li diffusivities at room temperature. The results are compared to Li tracer diffusion experiments conducted in our laboratory by secondary ion mass spectrometry (SIMS). SIMS measurements yield Li diffusivities several orders of magnitude lower than GITT measurements for Li0.02Si films. In contrast, both methods give a diffusivity of about 10–20 m2/s for Li0.25Si films. The results can be explained by a heterogeneous electrochemical lithiation mechanism of the electrode material.