Why did you keep 0 V DC bias? Change the DC bias and check the Nyquist plot. If possible, clarify the data on another instrument (not CH).

Have a look at attached note.

J.-P.

http://www.bio-logic.net/wp-content/uploads/AN49-Potentio_vs_galvano_EIS.pdf

Hello Dr. Sarkar, thank you very much for your comments. The DC biasing voltage you are referring to is init E voltage which is zero in my case? I kept it zero because so that i can have a reference voltage for every other cell. If i try OCV then it change with battery. Can you please  share the impact of using  zero DC biasing voltage for impedance study? 

 Also If you see in the bottom of the attached picture " Bias DC Current During Run below 1 Hz". Do i need to use it for all the frequencies? 

Thank you for your time.

Thank you Dr. Diard for the wonderful documents. 

As Sujoy Sarkar. Set : VDC bias= OCV.

Hi Vivek,

As you mentioned in your queries that you are unable to find the Warburg tail in your impedance spectrum. Therefore, I asked why did you keep the DC bias at 0 V because if you look at your CV, you will not find any current due to the diffusion at 0 V. Then, how did you expect Warburg tail at that potential?  

As Prof. Ioannis Samaras suggested, you should keep that at the OCP and after performing impedance study you should not use the cell for any other characterization.

The Warburg tail is, always, "lost", when a very high (DC[1]) current is passing through a (Li-ion battery) cell.

1.   On the contrary, if you set : VDC bias= OCV, then iDC~0.

Open circuit potential appear to be better way to understand the Impedance feature , it is in the non biased form.

Therefore potentiometric form is better , I my saying.