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# Electrochemical Impedance Spectroscopy with ADALM1000

I am trying to use the ADALM1000 for Electrochemical Impedance Spectroscopy with Lithium-Ion-Batteries.

I know, that Analog Devices has a dedicated Device for that use case, but as my Prof wants me to use the M1K, I'm trying to find a solution.

These are my Questions:

1. Is this task even possible with the M1K?
2. If it is, how is it done?

I tried it, by connecting the Battery as shown below (except Rcal was 10 Ohms), using Bode Plotter and Impdence Analyzer but Alice Suite always crashed so I assume that I did something wrong...

• Hi:

I have not tried measuring the dynamic impedance of a Li-ion battery. But I have used the M1k to charge one. While charging I superimposed a small AC waveform (triangle) on top of the DC charging voltage. I then calculated the effective DC resistance from the change in the measured current (CHA-I) and the amplitude of the added AC. I got less than 1 ohm I think.

Now looking at your schematic it appears that you have not included a DC offset in the signal being applied across the cell from CHA. By doing this you have effectively shorted out the battery. Thus the M1k will likely crash. Don't know how big the battery you are using is but my guess it can supply more than the 200 mA limit of the M1k SMU.

So assuming the Li-ion battery has a nominal 3.7 V output, set CHA Min to 3.6 and Max to 3.7 (or to what ever levels keeps the DC part of the current less than 200 mA. You can check your set up using the Scope Time traces to insure the voltages and currents are proper and within limits.

If you want the impedance of the battery you want to put the battery connected between ground (-) and BIN (+) (Channel B in Hi-Z Split I/O mode) and the reference resistor (10 Ohms I guess in your case) between CHA and BIN / battery (+). The ALICE impedance calculation assumes the DUT is between ground and BIN ant that is the result reported.

Hope this helps explain your problems. I can try to do a similar experiment with my Li-ion battery at some point (but not right now).

Doug

• Hi Doug,

thanks for the quick reply. I will try to implement your suggestions in a timely manner and get back to you with any results or follow up issues.

Thank you very much,

Yannik

• Hi:

I've done some impedance testing on a small Li-ion cell since you posted this question and have published this lab activity on the ADI Wiki:

https://wiki.analog.com/university/courses/alm1k/alm-eis-lab

In the process of doing these experiments I saw some places in the ALICE code that needed changes / improvements to test and display the very low impedance values and low test frequencies (down to ~1Hz). These additions to ALICE are included in the January update release done last week:

https://github.com/analogdevicesinc/alice/releases/tag/1.3.12

Using this latest software and M1k I was able to generate impedance plots similar to those shown in the CN0510 reference design.

Doug