Details

The Warburg impedance is the diffusional impedance for the diffusion layer of infinite thickness, which is characterized for the macroelectrode.

The Warburg impedance is given by , where is the relative parameter of the charge transfer and the diffusion coefficient ,

,

where , are heterogeneous kinetics on the electrode and , are the diffusion coefficients of the species oxidant and reductant.

With Warburg impedance, one can describe an electrochemical cell for the macroelectrode by the Randles equivalent circuit: