On the Origin of Phase Angle in Warburg Finite Length Diffusion Impedance

摘要

We develop a simple physical model which describes the origin of phase angle of the Warburg finitelength diffusion impedance. We show that diffusion results in a phase delay of the surfaceconcentration of species with respect to current. The phase shift between current and concentration is afunction of a ration of the Nernst diffusion layer thickness to an oscillating length. The phase angle ofthe Warburg finite length diffusion impedance has a maximum that does not depend on either theNernst diffusion layer thickness values or the diffusion coefficient of species. The peculiarities of thephase angle changes at the transition from the Warburg finite length diffusion impedance to electrodeimpedance are shown. The effects of the Nernst diffusion layer thickness, charge-transfer resistance,diffusion coefficient, double layer capacitance, and electrolyte resistance on the behavior of phaseangle are discussed.