Dear Zaidi , EIS equivalent circuit is basically should simulate your electrode/electrolyte system . We should use the right components according to both the structure of your system and the shape of both Nyquist and Bode plots. Rs should be a positive value but sometimes we observe a resistance loop in the negative value that indicates the inductive behavior of your system but this is a little bit uncommon especially for your system. In any case, Rs is the intersection with the x-axis i.e at -Z'' equals zero. Unfortunately, I could not open your file ! could you send your data in an excel format? and please give me a detailed description of your system , what is the nature of your support electrode? is there any other films on the electrode or the polymer film? what is the nature of the electrolyte? all of this information helps in getting the best equivalent circuit for the best fit.

thanks for your description, I have mentioned about blocking electrode, I am using stainless steel. the reason of negative value may be as I think is not smooth surface of my film. I can't tell you all about my material but its polymer based and completely solid polymer electrolyte.

actually I am using Z-VIEW software to fit my EIS data, there i have used CPE Equivalent circuit with parallel resistance but my semicircle is like suppressed instead of depressed. I believe the non homogeneity or rough surface could be the reason behind such plot.

Hello Zaidi Syed Danish Ali

It seems your Rs value is approx. 482 ohm and Rct value approx. 1198 ohm. These values are very large regarding to conductivity aspect of your material. However, You tried to fit with CPE. but, all the time, CPE can not be the only ckt to fit with nyquist plot. there are other circuit components such as mass capacitance, leakage resistance, warburg component etc. which altogether help to match nyquist plot accurately. So, try to involve them. Maybe you can omit the negative value of fitted Rs.

you can go through my publications for details. Here I'm attaching a few here.

Article Hexagonal VS2 Anchored MWCNTs: First Approach to Design Flex...

Article V2O5 encapsulated MWCNTs in 2D surface architecture: Complet...

Article Free-standing flexible MWCNTs bucky paper: Extremely stable ...

thanks for reply, how did you calculate those values?

Did you use any equivalent circuit to calculate these values?

thanks for sharing your article I would see

Zsimpwin software is generally used to find the equivalent ckt. you have to fit the the exact ckt among several ckts given in Zsimpwin software. The exact fitted ckt includes some ckt components which have specific values. You can check it by the 'save parameters' option. actually, whenever a specific ckt is assigned for fitting, the ckt components check the all possible values and exhibit the optimum values for accurate fitting with minimum error value.

You can calculate Rs and Rct directly through nyquist plot and can match with values of fitted ckt . The calculation of Rs and Rct are given in all of my papers. plz check.

What is the content of input file to zview software and in what format should it be?

we are using VERSA STUDIO software for EIS plot, And this software has option to export this plot to zview