It was demonstrated that chemical diffusion coefficients evaluated using electrochemical impedance spectroscopy were spurious, since any reaction kinetics were neglected in galvanostatic intermittent titration technique theory. The neglect of the reaction kinetics led to a spurious potential dependence of the electrochemical impedance spectroscopy diffusion coefficients with minima at those potentials where the slow scan rate cyclic voltammogram or differential capacity plot exhibited peaks even in cases where the true chemical diffusion coefficient was constant. This was demonstrated by the evaluation of electrochemical impedance spectroscopy diffusion coefficients from numerically generated electrochemical impedance spectroscopy experiments calculated with a constant chemical diffusion coefficient on the example of a spinel-type LiMn2O4 electrode.

Spurious Chemical Diffusion Coefficients of Li+ in Electrode Materials Evaluated with GITT. E.Deiss: Electrochimica Acta, 2005, 50[14], 2927-32