Does Warburg impedance predict zero DC current in an Electrode/Electroyte interface?

I'm trying to understand how/if the Warburg impedance, Z\_w, of an electrode-electrolyte interface dominates the impedance at low frequencies. I cannot understand how this model can predict a DC current flow.


A commonly used electrical model of a Faradic electrode is from e.g. [1](https://i.stack.imgur.com/sBAFA.png):
[![Interface with charge transfer resistance R_ct in series with Warburg impedance Z_w](https://i.stack.imgur.com/sBAFA.png)](https://i.stack.imgur.com/sBAFA.png)


where R\_ct is the charge transfer resistance, C\_d is double layer capacitance and R\_b is the bulk resistance.


I found an approximation of Z\_w here:
<http://www.consultrsr.net/resources/eis/diffusion.htm>
[![Equations for Warburg impedance vs. frequency w](https://i.stack.imgur.com/MbHQ4.png)](https://i.stack.imgur.com/MbHQ4.png)


According to this, the Warburg impedance approaches infinity as frequency approaches zero. This means that in the model in ref [1](https://i.stack.imgur.com/sBAFA.png), there would be no DC current flow. Yet in ref [1](https://i.stack.imgur.com/sBAFA.png) they say "At low frequencies, the effect of Warburg impedance can be neglected
and the element in series with the diffusion impedance is merely Rct..."


This is where I get confused. I would be grateful for any help/guidance on this.


Thanks,
Bjorn


[1](https://i.stack.imgur.com/sBAFA.png) Comprehensive study of noise processes in electrode electrolyte interfaces
Arjang Hassibi,a) Reza Navid, Robert W. Dutton, and Thomas H. Lee, Journal of Applied Physics 96, 1074–1082 (2004)


<http://www-smirc.stanford.edu/papers/JAP_04_Electrode_Noise.pdf>


