Werner Strunz, Zahner-elektrik.

Transcription

1 Werner Strunz, Zahner-elektrik

2 Overview Experimental Challenges for Battery-Measurements Magnetical Artefacts Time-Drift From Single Cell to Multi-Cell (Stack) Set-Up for High Power Handling ( Hard & Software in stack measurements)

3 Problems of Daily Life

4 Mutual Induction Origin and Elimination Interaction magnetical/electrical field => Drilling of Cables.

5 Battery under Load - (Mutual) Inductance & Drift High-frequency Data (inductance) With kind permission of R. Gross, bno-consult, Dettelbach

6 Drift Superposition of Additional Quantity drifted realtime signal E' [ o (t)] online correction Online Drift Compensation (more than one wave required) corrected signal E [ o (t)] ( High Frequencies )

7 Battery voltage / V Drift in Batteries 3,26 Discharge 4A (0.1 C) Relaxation 0A 3,25 3,24 3,23 3,22 3,21 3,20 2,0 2,2 2,4 2,6 2,8 3,0 3,2 3,4 3,6 3,8 4,0 4,2 time of experiment / h Measurement time ~ 6 h

8 Restriction (2-Gate) Z-HIT Validation of Spectra: Z-HIT (I) Considering Kramers Kronig relations ) ( Re 2 = ) ( Im d H PV H ln ) ( ln ) ( 2 onst.+ ) ( ln 0 0 d d d c H O S Integral-Term preserved integration along the frequency axis leads to weighting (measuring time)

9 Z-HIT (II) Randle circuit with NTC as Charge Transfer Resistance

10 Validation : Z-HIT (III) Randle circuit with NTC as Charge Transfer Resistance Only Smoothing Z-HIT refinement Dangerous: expanding the model without physical justification

11 Neutron Imaging (FC) Sudden Decrease of Temperature Condensation of water in flow-field

12 Stacks - Experimental Set-up (I)

13 Stacks - Experimental Set-up (II) Additional, Third Party Electronic Load (DC-Bias 340A) EIS-Optimized Load for DC Bias (60A) and AC-Modulation Electrochemical Workstation Multichannel Add-IN for Simultaneous EIS Measurements

14 From Single Cell to Stacks - Simultaneous Measurement Left Sequential Right Parallel Simultaneous

15 Stack Measurement at 400 A DC

16 Ergebnisse einer Hochstrom-EIS-Messung am Batteriestapel: Zeitlicher Gang Measurement only to 0.5 Hz But Drift Detectable (400 A) Replacement of Impedance by Z-HIT Prediction

17 Simplified Model of Stackimpedance

18 Check of Result/Model - Significance S i = max d Z n P i d P i Z n with d Z n = Z n - Z n Are All of the Parameters Meaningful?

19 Significance of the Particular Elements

20 Summary

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22 History (Time) Preserving Randle circuit with NTC as Charge Transfer Resistance Only Smoothing Z-HIT refinement

23 Seeing the Bigger Picture With kind permission of R. Gross, BNO-Consult Würzburg

24 Seeing the Bigger Picture > With kind permission of R. Gross, BNO-Consult Würzburg

25 * * * * Strategien bei der Mehrkanal-EIS-Datenerfassung anode cathode A : Connector inductivity B : Connector resistance C : Charge transfer A C E B D F G (Faradayic) processes D : Double layer capacity E : Porous distribution F : Bulk inductivity G : Bulk (electrolyte, membrane) resistance

26 The Z-HIT Approximation (evaluation of impedance modulus from the phase angle ln H ( 0 ) const S ( ) d ln d ( dln O ) Detection of artifacts Detection of instationarities (drift) History (time) preserving Reconstruction of causal spectra => Reliable interpretation of spectra

27 Validation of Spectra Z-HIT

28 ln Z Deduction of the Z-HIT Randle circuit E ( O ) S Phase / rad 0,0 16-0,2 15-0,4-0,6 14 Integral (shifted) ln Z [A] ln -0,8-1,0-1,2-1, [B] ,5 0,4 0,3 0,2 0,1 0,0-0,1-0,2-0,3-0,4-0,5-0,6-0,7 [C] ln Z - Integral () d / dln ,5 0,4 0,3 0,2 0,1 0,0-0,1-0,2-0,3-0,4-0,5-0,6-0,7 [D] ln Z - Integral () /6 * d / d ln