The Warburg impedance is the diffusional impedance for 1D linear diffusion. This Demonstration shows the Randles equivalent circuit, taking into account the electrolyte resistance , the charge transfer resistance , and the double layer capacitance . Various shapes of the impedance diagram can be obtained when changing the parameter .
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: