A POSSIBLE WAY TO MEASURE LITHIUM ION DIFFUSION COEFFICIENT FOR Li INSERTION THIN FILM WITH UNKNOWN Li COMPOSITION: APPLICATION TO Li_\alphaCoO₂ and WO₃

In this paper, a new experimental method of lithium ion diffusion coefficient measurement for lithium intercalation thin film material is presented. This exper-imental method is feasible and can be applied to thin films with unknown lithium composition such as Li_\alphaCoO₂ etc. To check its validity, we used the impedance spec-troscopy method to make a verification on the WO₃ thin film sample with known lithium composition.