EIS quality indicator by Bio-Logic, Because linearity matters
THD, an EIS quality indicator
Electrochemical impedance spectroscopy (EIS) measurements at two different AC amplitudes (50 mA & 400 mA) are performed on the same Li-ion battery cell. The non-linearity of the cell at low frequency is evident in the Nyquist plot above.
After an equivalent circuit fit analysis, the charge transfer resistance is over-estimated by 8% with the 400 mA AC amplitude measurement. The THD indicator can be used to detect this non-linearity and help optimize the stimulation amplitude
Click here to view a Z fit tutorial by Bio-Logic.
Please don’t hesitate to contact us if you are based in Scandinavia and would like to have more info about the THD.