We propose that the intercalation of ions from a liquid electrolyte into a solid material can be analyzed in terms of a model [J. Appl. Phys., 55, 3341 (1984)] developed for the release of alkali ions from interface traps in a metal-oxide silicon structure. It is shown that the insertion of Li ions into Sn oxide is described very well by this model, and the diffusion coefficient of Li in the oxide as well as the release frequency of Li ions from surface traps could be obtained. The presence of current peaks in chronoamperometry curves could also be explained.