Hello experts,
At x °C, x SOC I did Electrochemical Impedance Spectroscopy on 2.5 Ah Li-ion battery (Full cell) and followed by discharge current pulse (2C) measurements. I fitted EIS through Zview using 4RC and current pulse through 2RC Equivalent ckt. But both the resistance obtained are different ? Eg: 0.06 ohm for current pulse and ~10 ohm for EIS. Which one is accurate ? Can anyone explain this ? Is there any way to compare these two measurements ?
Praveen, I have attached an open-access article which may help answer your question. Hope this helps.
- Jason
1) EIS q : Which one is accurate ?
2) Very challenging q : Is there any way to compare these two measurements?
Literally, the 2nd one "measurement", the discharge current pulse (2C) measurement(s), is a member from a big set. Another galvanostatic system will show another value for the "say a name R' for ~ 0.06 ohm" apparent (and illusive[1]) R'. Each galvanostatic system might have a specific frequency link in EIS, and lt will show another R for your samples, that are among the complex-Z systems
1. These measurements are build upon, not only, on
a) the specifications (of the galvanostatic system) but they depend on
b)the time and
c) the working conditions from the last calibration services (of the galvanostatic system).
Thank you so much Prof Ioannis. You answer almost all my questions, making my things easy. Once again thank you.
1) EIS q : Which one is accurate ?
2) Very challenging q : Is there any way to compare these two measurements?
Literally, the 2nd one "measurement", the discharge current pulse (2C) measurement(s), is a member from a big set. Another galvanostatic system will show another value for the "say a name R' for ~ 0.06 ohm" apparent (and illusive[1]) R'. Each galvanostatic system might have a specific frequency link in EIS, and lt will show another R for your samples, that are among the complex-Z systems.
1. These measurements are build upon, not only, on
a) the specifications (of the galvanostatic system) but they depend on
b) the time and
c) the working conditions
from the last calibration services (of the galvanostatic system), etc.
The EIS is related to the pulse resistance. The impedance in the EIS at different frequencies is different. The pulse resistances during different time scales are also different. But these two types of impedance are linked to each other. For example, the 1s resistance (pulse resistance) can be expressed by the EIS impedance.
Let me rewrite:
"For example, the 1s resistance, z'(t), for a VERY LOW (value of either ip, or Vp) PERTURATION, pulse resistance, can be correlated with the commonly measured EIS-impedance, Z(f)".
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