Hello everybody.
I am handling some data obtained with impedance measurements (EIS), and I was wondering which contributions does the high-frequency resistance (HFR) comprise.
In electrochemistry books, it is usually found as the intercept of the impedance circle with the real(Z) axis, at very high frequencies, and it is referred as "solution resistance" or "electrolyte resistance". My question is whether it accounts for other sources of ohmic losses (such as cables, connections and electrodes themselves), or it considers the solution only.
Thanks in advance.
Hello Carlo,
a small addition to Arman is that not only the electrolyte can contribute to the measured losses. Also passivation or degradation of the working electrode (like the growth of an insulating layer of oxide which leads to a drop in the conductivity through the electrode), bubbles formation, geometry of the working electrode and corrosion of the cables can affect (even dramatically) the value. This holds also when working with solid electrolytes like polymer electrode membranes, like Nafion 117 or 212, which are employed in fuel cells and electrolyzers. So in general, increasing the concentration of the supporting electrolyte does not lead automatically to lower ohmic losses.
Cheers,
Francesco
Hi Carlo,
HFR accounts for the sum of all the ohmic resistances present, including electrolyte, contacts, wires, etc. In many electrochemical systems, the ohmic resistance is dominated by the electrolyte that is why is it also referred to as the solution or electrolyte resistance.
Best,
Arman
Hello Carlo,
a small addition to Arman is that not only the electrolyte can contribute to the measured losses. Also passivation or degradation of the working electrode (like the growth of an insulating layer of oxide which leads to a drop in the conductivity through the electrode), bubbles formation, geometry of the working electrode and corrosion of the cables can affect (even dramatically) the value. This holds also when working with solid electrolytes like polymer electrode membranes, like Nafion 117 or 212, which are employed in fuel cells and electrolyzers. So in general, increasing the concentration of the supporting electrolyte does not lead automatically to lower ohmic losses.
Cheers,
Francesco
Normally, HFR is associated to any serial contribution to the impedance, such as: electrolyte resistance, but also cables, oxides that inhibits the optimal conductivity in electrical in the working electrodes or current collectors.
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