Zhuang Quanchao

Electrochemical Impedance Spectra of Intercalation Compound Electrodes:Models and Theoretical Simulations

Single intercalation particles,mixed particles,homogeneous porous electrodes and nonhomogeneous,multilayered porous electrode models are proposed in this paper.Some peculiar features of impedance spectra were simulated using the above-mentioned models.The results reveal that the features of impedance spectra of the single intercalation particle and the mixed particles are the same and the features consist of lithium ion migration through the solid electrolyte interphase(SEI) film(R_(SEI)||C_(SEI) semicircle),an electron and ion transfer process(R_(ct)||C_(dl) semicircle),and a finite-diffusion Warburg element.For the nonhomogeneous,multilayered porous electrodes model,a peculiar feature of impedance spectra is that a new arc appears in the Nyquist plot.A detailed analysis revealed that a different particle size distribution could lead to the appearance of a new arc and a different layer distribution(a thicker layer and a thinner layer),which could lead to a well-developed semicircle.