FRACTAL DIMENSION OF LI INSERTION ELECTRODES STUDIED BY DIFFUSION-CONTROLLED VOLTAMMETRY AND IMPEDANCE SPECTROSCOPY

we show that a unique fractal dimension can be obtained for Li inserti on electrodes by applying two different electrochemical methods to sam ples of porous Sn oxide and Ti oxide. The first method relies on the a ssumption that the current recorded in voltammetric experiments, condu cted in a Li containing electrolyte, is limited by Li diffusion from t he fractal working electrode surface into the oxide matrix. The second method is based on the capacitance dispersion observed in impedance s pectroscopy. Simple scaling arguments show that this capacitance dispe rsion is related to the fractal structure of surface roughness.