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Popular topics · Measurement quality and accuracy

How is EIS measurement quality verified on high-power batteries?

The power stage needed for high current slows the response, while high-frequency EIS needs a fast galvanostat. Instrument and booster combinations are compared on a 94 Ah cell using the THD of the excitation current.

Key points

  • Analogy: it is hard for a vehicle to be as powerful as a truck and as fast as a race car. The instrument and its settings must be balanced for the test and the device under test.
  • GEIS can be performed on a battery stack with an Essential-range potentiostat and a FlexP external booster (details in Bio-Logic AN59).
  • Here THD is used on the excitation current (THD I) to measure the linearity of the instrument rather than the system, avoiding misinterpretation caused by battery behaviour.
  • With an SP-150e + FlexP 0012 at 10 A amplitude on a 94 Ah cell (about C/10): THD is below a few percent from 0.1 Hz to 1 kHz and 2.8% at 1 kHz; non-linearity begins above about 2 kHz. It is suitable for single-frequency 1 kHz AC internal resistance tests.
  • THD I at 1 kHz and 10 A: SP-150e + FlexP 0012 (200 A) 2.8%; HCP-1005 (100 A) 2.9%; BP-300 (10 A) 0.1%. THD increases with power, but all values are low enough for reliable measurements.

Figures

Analogy: combining the strengths of a powerful truck and a fast race car in one vehicle is hard; so is combining high current with high-frequency speed.
Figure 1. Analogy: combining the strengths of a powerful truck and a fast race car in one vehicle is hard; so is combining high current with high-frequency speed.
GEIS on a battery stack with a VMP3 and a FlexP 0060 external booster: Nyquist plot at the mΩ level.
Figure 2. GEIS on a battery stack with a VMP3 and a FlexP 0060 external booster: Nyquist plot at the mΩ level.
THD of the excitation current in 10 A GEIS on a 94 Ah cell: 2.8% at 1 kHz; non-linearity begins above about 2 kHz.
Figure 3. THD of the excitation current in 10 A GEIS on a 94 Ah cell: 2.8% at 1 kHz; non-linearity begins above about 2 kHz.

Images: Bio-Logic Science Instruments; taken from the source article.

Related application notes

Related curriculum module: Electrochemical Impedance Spectroscopy (EIS)

Related products:FlexP SeriesSP-150eHCP-1005VMP-3e
Source: Bio-Logic Learning Center, “Ensuring the quality of Electrochemical Impedance Spectroscopy measurements on high-power systems” · Source updated: November 18, 2024
Copyright of the images and the original text belongs to Bio-Logic SAS.

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