The essense and purpose of Batixt R3 EIS method and instruments is to enable anyone, anywhere in the battery value chain to get the data they need to make smarter decisions and better batteries.
On this page, we have published examples that demonsrate new and unique capablities that the R3 EIS method brings to your table.
Note: Results presented here reflect raw data, directly from Batixt R3 EIS instrument prototypes: Sense, Clarity and Vision
Read more about capabilities within three important areas: Cells & Materials, Cell Production and Cell Life/Use and Re-use
With the R3 EIS instruments, one single EIS Scan delivers accurate impedance data for hundreds or thousands of frequencies in a full frequency spectrum from 10 mHz to 10 kHz.
Note that all frequencies in the spectrum are measured simultaneously, not sequentially as is normally required to achive full-spectrum EIS results.
Instrument: Clarity
Measurement Configuration
Measurement direction: Charge and Discharge
Measurement time: 84 s per scan
Test Current: 0.5 – 1.5 A
Frequency separation: 1-2%
Batteries
Multiple 18650/21700 cylindrical cells
Varied ageing and models
The capability to perform these high-resolution, full spectrum EIS scans repeatedly over entire charge and discharge cycles generates unprecedented data sets that allow the closer study of the batteries electrochemistry while in motion. Below are two examples of charge respective discharge cycle results.
Instrument: Clarity
SoC Sweep
Measurement direction: Charge
Number of EIS Scans: 250
Number of datapoints: 89 000
First scan: 2.7127 V
Last Scan: 3.3109 V
Individual Scans
Test current: 0.25A
Datapoints per scan: 356
Lowest frequency: 0.0715 Hz
Highest frequency: 9886 Hz
Battery
Pouch 1.2 Ah
Instrument: Vision
SoC Sweep
Measurement direction: Discharge
Number of EIS Scans: 777
Number of datapoints: 276 612
Individual Scans
Test current: 20 A
Datapoints per scan: 356
Lowest frequency: 0.0715 Hz
Highest frequency: 1000 Hz
Battery
Module with 18650 cells, 210 Ah
Results are highly repeatable. The following examples demonstrate repeatability over several measurements when measurement time and current were varied..
Repeatability over measurement times
Measurement direction: Discharge
Test Current: 1 A
Freq. Separation 2%
Scan 1: 5s, 0.5722 – 5000 Hz, 3.570 V
Scan 2: 10s, 0.2861 – 5000 Hz, 3.568 V
Scan 3: 21s, 0.1431 – 5000 Hz, 3.566 V
Scan 4: 42s, 0.0715 – 5000 Hz, 3.552 V
Scan 5: 84s, 0.0357 – 5000 Hz, 3.556 V
Battery
18650 Cylindrical cell
Repeatabiity over test currents
Measurement direction: Discharge
Measurement time: 42 s
Lowest frequency: 0.0715 Hz
Highest frequency: ~ 10 000 Hz
Freq. Separation 2%
Scan 1: 0.50 A, 3.586V
Scan 2: 0.75 A, 3.575V
Scan 3: 1.00 A, 3.564V
Scan 4: 1.25 A, 3.554 V
Scan 5: 1.50 A, 3.542 V
Scan 6: 1.75 A, 3.531 V
Battery
18650 Cylindrical Cell
The signal noise ratio is exceptional considering R3 EIS represents very broad band multisine measurement. The SNR value is delivered for each frequency in the impedance results. Below is a single measurement followed by two views of the associated SNR values for each frequency in the impedance spectrum. In this exampel the lowest SNR for a single datapoint is 10^2.7 and the highest is 10^4.1.
Discharge R3 EIS Scan
Measurement Time: 42 s
Current: 1.75 A
Frequency separation: 1%
Number of frequencies: 632
Lowest frequency: 0.0714 Hz
Highest frequency: almost 10 000 Hz
Highest SNR: 10^4.1
Lowest SNR: 10 ^2.7
R3 EIS is uniquely suited for high-resolution and continuous measurement under realistic operating currents, bringing you closer than ever to in-opeando processes in the battery.
With R3 EIS you can gain exceptional access to the inner workings of the formation of the batteries electrochemistry.
In the first diagram below, the formation process has been performed using Batixt R3 EIS instrument and with continuous EIS measurement during the cycling.
In the second diagram, results from measurement of almost 400 21700 cylindrical cells at the same SoC are presented to illustrate cell variation. Least variation is observed at 1 kHz and most variation (+/- 5%) at approximately 10 Hz.
Instrument: Sense
Battery
Coin Cell
Instrument: Sense
Battery
Coin Cell
Instrument: Clarity
Batteries
21700 Cylindrical Cells
Below is an illustration of how the SoC sweep of full spectrum EIS scans can be analysed. In the first figure, the modules induction is masking the ageing. The data was therefore modelled to separate the induction and enable a clearer view of the electrochemistries ageing, as dependent on SoC. The separted results are shown in figure 2 (Capacitative Reconstruction) and figure 3 (Inductive Reconstruction). Finally in figure 4, generalised distribution of relaxation times is used to visualise the time scales of the batteries electrochemical processes.
Measurement Type
Full State-Of-Charge Impedance Sweep of EIS Scans in Discharge mode.
Measurement Time: 84 seconds per EIS Scan
Measurement Current: 16A
Signal Separation: 1%
Lowest Frequency: 0.036 Hz
Displayed: 70 EIS Scans, 49 100 datapoints
Dataset: 700 EIS Scans, 491 000 datapoints
Below are the results of a study whereby a module was disassembled and the 72 cylindrical 18650 cells within were measured. The module was aged. This demonstrates multiple possibilities to understand how cells age and degrade in modules.
Instrument: Clarity
In industry where the volumes of batteries handled is growing fast, the capability to quickly gain accurate insight into a batteries state of health is essential. The results in this section represent snapshots from work Batixt have been doing on developing a methodology for classifying batteries state of health and understanding it’s usefulness in for example second-life decision making.
