In order to estimate the solid-state diffusion coefficient of Li in Li-intercalated C electrodes, a new model was developed which was based upon the galvanostatic intermittent titration technique. The concept of a constant phase element was introduced in order to account for the roughness of the electrode. The Li diffusivity in pyrolytic C, coke and mesophase C was calculated by fitting the voltage response, due to a constant low-current perturbation, using the proposed model. It was found that the use of the constant phase element led to a two orders of magnitude increase in the estimated diffusivities.

P.Liu, H.Wu: Solid State Ionics, 1996, 92[1-2], 91-7