A POSSIBLE WAY TO MEASURE LITHIUM ION DIFFUSION COEFFICIENT FOR Li INSERTION THIN FILM WITH UNKNOWN Li COMPOSITION: APPLICATION TO Li α CoO 2 and WO 3

In this paper, a new experimental method of lithium ion diffusion coefficient measurement for lithium intercalation thin film material is presented. This experimental method is feasible and can be applied to thin films with unknown lithium composition such as Li?CoO2 etc. To check its validity, we used the impedance spectroscopy method to make a verification on the WO3 thin film sample with known lithium composition.