Hello all!
I'm running some EIS measurement on an insertion type material for hybrid supercapacitors, right now I am varying the potential and measuring EIS at different potentials. At higher potentials I see the normal semi-circle at higher frequencies but when I decrease the potential 'induction type' loops start appearing, what could be the reason for this?
The explanation I have read mostly is related to cables and contacts but this is not the case here since I use the same setup in all my measurements and they do not appear all the time.
Some technical details:I run my measurement at 1MHz in a 3-electrode swagelok cell, stainless steel rods, copper current collectors, Ag/Ag+ pseudo-ref and an ionic liquid based electrolyte.
Thanks for any input!
Hello Jacob!
I have attached a figure with three different spectra using the same sample acquired in subsequent measurements. The blue is at 0V, the purple is at around -1V and the green is at -1.8V.
Thanks for your help!
Hello Simon ! Very nice graphs ! This loop is definitely not due to cables as it would appear at much higher frequencies. Could you provide the I-E characteristics of your system ? Could you also provide the frequency range that you are using and at which frequencies this loop appear ? Thank you, Nicolas
Hi Simon ! This inductive behavior at medium frequencies could be due to an EE mechanism. Please see attached paper for more details. Let me know if you need further explanations. Best regards, Nicolas.
Hi Simon,
Inductive ring (loop) is caused by the electrochemical adsoption and desorption.
And it is related to the attached or detached (+)/(-) charge. In your case, a difference potential means the different current and the electrochemical reaction speed.
generally inductive at high freq. range is caused by reaction and indictive at low freq. is caused by charge diffusion.
Sorry for the late reply! But thanks for the good feedback! Regarding the EE reaction, what would be the mechanism behind that? Electrolyte decomposition? Nicolas Murer
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