Hi Zakaria

Try to fit your impedance profile with equivalent circuit, so that you can get the values of all resistance. Or else in X axis, from zero to your first impedance point known as the solution resistance.

Best regards,

Bhabu

Hi

https://www.gamry.com/assets/Uploads/Basics-of-Electrochemical-Impedance-Spectroscopy.pdf

slide 16 -> Ru :-)

Best regards,

Andreas

Thank you for your answer Andreas Heyn. But what I want is a method to get it from my data since that I don't have the value when Zim=0 (as you can see in the attached image).

X intercept of the semicircle gives solution (electrolyte) resistance

Hi

I do agree with Andreas.

Use a soft ware by Gamry or elsewhere to best fit your Nyquist data to Randle's equivalent semi-circle. Then,the lower intersection point of Randle's equivalent semi-circle with the abscissa ordinate(X-axis or horizontal axis) wii be the solution (Ohmic)resistance;Rs.

Hi Zakaria

Try to fit your impedance profile with equivalent circuit, so that you can get the values of all resistance. Or else in X axis, from zero to your first impedance point known as the solution resistance.

Best regards,

Bhabu

Dear Benbouzid Abdelmoheiman Zakaria ,

your EIS locus is, mainly, on a WE-"context", all about a WE focus, ... not about your solution properties.

However, a part, only, of your solution resistance (as a "byproduct"-hint) might be estimated as a small percentage, contained in the composite resistance value, proposed by the "Gamry[1] method"; then, proceed with a helpful fitting[2].

Also, if the electrolytes' resistance is critical for your project then, apart from a specific (descent) measurement, you can have a realistic (approximative resistance) value. Remake similar EIS, but, use, now, three different electrolyte's concentrations; the above fitting-method[2] will result in a useful (practical) resistance value, e.g. get the (initial) electrolyte(s) resistance, from these (three) Nyquist Plot(s), by excluding the other[3] values, excluded, virtually, from the common EIS[4] (WE-locus).

1. Andreas Heyn : slide 16 -> Ru :-)

https://www.gamry.com/assets/Uploads/Basics-of-Electrochemical-Impedance-Spectroscopy.pdf

2. Implementing the fitting proposed in Amarsingh Bhabu Kanagaraj 's answer.

3. the non-electrolytic origin, contributions from the (fitting-method based) composite resistance.

4. For a cell having a three-electrode configuration.

Thank you all for your help.

If you want to prove to yourself that this is the answer then you could try moving the referencer electrode away from the WE - and see if it changes

Remember that this is the measured electrode resistance of your cell, which is different to an actual measure of solution resistance

Thank you Nicholas Farmilo,

ok I will do that.

Also, we could try to adjust the position of the RE (referencer electrode), in respect to the direction of the cell's current (iWE,CE). The most interesting locations are, at least, three :

two "cis" (back, or forth) and

one "trans", location.

Try to fit your Nyquist plot on CHI or autolab analyser by simulating it or fit into the software. It is much better than guessing on manual method and off course it is not possible in your system at all. Similar nyquist plot appears in conducting polymeric study.