Impedance model of the cathode catalyst layer

In this chapter, a mathematical model based on fundamental electrode theory to simulate the impedance spectrum of the cathode catalyst layer (CCL) is developed. This chapter also provides a brief discussion about the transmission-line model which is commonly considered to represent the impedance response of porous electrodes. The derivation of the impedance model of the CCL is carried out in two steps. First, the impedance model of the CCL neglecting oxygen transport limitations is developed. Second, the effect of oxygen transport limitations on the impedance response of the CCL is considered in the mathematical treatment. The developed impedance model of the CCL is analogous to the transmission-line model and considers electro-diffusion phenomena of the CCL. It is possible to gain an insight into the electrochemical phenomena of the CCL represented in the impedance spectrum at different frequencies.