Li-ion diffusion behavior in Sn, SnO and SnO2 thin films studied by galvanostatic intermittent titration technique

Abstract Poorly crystallized Sn, SnO and amorphous SnO 2 thin films have been prepared by radio frequency magnetron sputtering on Cu substrates and have been characterized by X-ray diffraction, scanning electron microscope and Raman spectra. The electrochemical performance of the thin films has been studied by galvanostatic cycling and cyclic voltammetry. The apparent Li-ion chemical diffusion coefficients, D Li , of the films have been determined by galvanostatic intermittent titration technique (GITT). It is found that the D Li values by GITT are in the range of 10 − 16 to 10 − 14  cm 2  s − 1 for the metallic Sn film and 10 − 15 to 10 − 13  cm 2  s − 1 for the tin oxide films. The improved Li-ion diffusion rate in the oxide films than in the metal film is due to its unique microstructure formed during the first cycle, namely, a uniform dispersion of Li δ Sn (0 ≤ δ ≤ 4.4) in the Li 2 O matrix.