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© Fraunhofer THERMISCH-ELEKTRISCHE BATTERIE- MODELLIERUNG W. Beckert, Christian Freytag, T. Frölich, M. Wolter.

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Presentation on theme: "© Fraunhofer THERMISCH-ELEKTRISCHE BATTERIE- MODELLIERUNG W. Beckert, Christian Freytag, T. Frölich, M. Wolter."— Presentation transcript:

1 © Fraunhofer THERMISCH-ELEKTRISCHE BATTERIE- MODELLIERUNG W. Beckert, Christian Freytag, T. Frölich, M. Wolter

2 © Fraunhofer 2 Fraunhofer Institut f. Keramische Technolog. u. Systeme Dresden Arbeitsgruppe Modellierung und Simulation: Multiphysics-Feldsimulation (FEM, CFD); Reaktive Strömung; homogenisierter Ansatz für heterogene Mesostrukturen; (Systemsimulation) Thermisches Management von Energiesystemen,... (SOFC-Stacks + Komponenten, thermoelektrische Generatoren, Li-Ion-Batterien,...) H igh -T emperature -F uel -C ell -SystemsT hermo -E lectric -G enerator D iesel -P articulate -F ilter

3 © Fraunhofer 3 Our Model Approach for Batteries

4 © Fraunhofer 4 Homogenisation model for winding body PDE: anode side charge balance/ potential PDE: cathode side charge balance/ potential Constitutive equ.: electric characteristics winding PDE: thermal balance current collector porous cathode porous anode isolator separator/ electrolyte current collector cell laminate anode side current distributor phase cathode side current distributor phase "el.-chem." active phase: transverse charge transfer simplified 3-phase homogenised continuum approach intrins. potential polar. resistance DOF: U ano U cath T composite homogen. composite volume element combine into transverse (electrolyte) current density

5 © Fraunhofer 5 Model for local electrical characteristics Constitutive equation for el.-chem. active phase: [C. M. Shepherd "Theoretical design of primary and secondary cells. Part 3: battery discharge equation" NRL Report 5908; May 1963 Empirical Approach: Shepherd's Model [1] intrinsic electrochemical potential cell polarisation resistivity

6 © Fraunhofer 6 Introduction into SHEPHERD-Model* Discharge: Charge: * ref.: [1]

7 © Fraunhofer 7 Discharge example from SHEPHERD-Paper (NiCd-cell): Introduction into SHEPHERD-Model

8 © Fraunhofer 8 Extensions and adaptions to original SHEPHERD-Model: Introduction into SHEPHERD-Model  only valid for isothermal and galvanostatic conditions for OCV* for linear range * ref.: [2]

9 © Fraunhofer 9 Thermal-dependence of SHEPHERD-parameters: LFP C-Cell Introduction into SHEPHERD-Model

10 © Fraunhofer 10 transient battery model [3, 4, 5]: extended SHEPHERD-Modell (i≠const) transient term + Introduction into SHEPHERD-Model non-galvanostatic part galvanostatic part(i=const) open circuit voltage (equilibrium)

11 © Fraunhofer 11 Models and Results (Batterie Cell Level)

12 © Fraunhofer 12 Model Geometry: Example: cylindrical cell with contact tabs ( LiFePo 4, ANR 26650) separated current collector tabs, embedded between windings nonhomogeneous contacting with current concentration toward cont. tabs helical current flow + current collection  3D-model approach

13 © Fraunhofer 13 Hybrid 2D-3D Model with Thermal  Electric Coupling Concept: Combined 2D electric  3D thermal model for winding body electric problem: 2D frame U ano (l,y), U cath (l,y), j elek (l,y)  Q diss (l,y) thermal problem: 3D frame T(x,y,z) Map 3D  2D Temperature Map 2D  3D Dissipation Heat l y T(x,y,z) j elek (l,y) T Q diss COMSOL: allows integrated mapping + simultaneous cosimulation (unrolled electric film composite) (thermal composite) information transfer       rev uc elec diss d dddeffth Q h j T U T Q QT      0, )( jjσλ  T kk   TUU 00 

14 © Fraunhofer 14  t= 6 s Transient analysis with current pulse high dynamic load + small area contacts  hot spot formation (LiFePo4, 26650, R i = 10 m  ) pattern of hot spots, induced by contacting structure dynamic analysis current pulse: duration 6 s I max = 95 A = 40 C reasonable magnitude for practical operation temperature Hybrid-Model Results: 3D-thermal model branch

15 © Fraunhofer 15 Completion: 3D-Model with Housing Geometry/ Mesh generation winding domain: Comsol-generated add housing + contact structure: CAD-Import connecting meshs by interface elements

16 © Fraunhofer 16 3-D Model with Housing: Results Temperature [°C] 41.9°C 21.9°C 41.9°C

17 © Fraunhofer 17 Models and Results (System Level)

18 © Fraunhofer 18 Implementation in SimulationX 3.5 SimulationX 3.5 Modelica 3.2

19 © Fraunhofer 19 Implementation in SimulationX transient term 4

20 © Fraunhofer 20 Application on External Data Sources of used data: experimental data for LFP C-Cell: discharge 1C, 5C, 10C including temperature data data from COMSOL build-in battery-model [6]: pulse discharge: 1C, 5C no temperature data included  SHEPHERD-parameters via external data fit (Excel)

21 © Fraunhofer 21 Application on External Data Terminal voltage from a LFP C-Cell 1C2,1A 5C10,5A 10C21A

22 © Fraunhofer 22 Application on External Data Temperature profile during discharge of a LFP C-Cell

23 © Fraunhofer 23 Application on External Data 1C - pulse discharge for COMSOL-Model: peak17,5A duty cycle300s periode2000s

24 © Fraunhofer 24 Application on External Data 5C - pulse discharge for COMSOL-Model: peak87,5A duty cycle100s periode2000s

25 © Fraunhofer 25 Summary hybrid 2D-electric + 3D-thermal composite approach with  geometrical details  thermo-electric coupling  homogenised 3 phase model for winding composite  simple empirical model for electrical characteristics result: contact structure acts as source for thermal hot-spots in dynamic loads approach has potential for use in multi-cell models good, robust and simple model for description of terminal voltage resolution for isothermal and galvanostatic restriction of original model sufficiently accurate match between experiment and model

26 © Fraunhofer 26 Outlook "Virtual Battery Thermal Lab"-Tool: analyse/ understand internal thermal processes „benchmark" for simpler models tool for cell design optimisation IKTS activity: internal cell temperature sensor assist design process optimise sensor positioning analyse effects from interference of sensor-cell implementation of charge behaviour data fit in SimulationX/Modelica coupled thermal-electric model Prototype example: [IKTS] curved LTCC substrate thick-film resistor electrolyte tolerant resolution: +/- 0.6 K

27 © Fraunhofer 27 Wish List to Modelica simple data import to Modelica simple data fit function in Modelica (bidirectional) interface to FEM …

28 © Fraunhofer 28 References [1]C. M. Shepherd: Theoretical design of primary and secondary cells part III - battery discharge equation NRL Report 5908 Washington, D.C [2]O. Tremblay, L.-A. Dessaint, A. I. Dekkiche: A Generic Battery Model for the Dynamic Simulation of Hybrid Electric Vehicles Vehicle Power and Propulsion Conference [3]A. Jossen: Fundamentals of battery dynamics Journal of Power Sources 154 (2006) 2, S. 530–38. [4]N. Sekushin: Equivalent circuit of Warburg impedance Russian Journal of Electrochemistry 45 (2009), S. 828–32. [5]F. M. González-Longatt: Circuit Based Battery Models: A Review 2do congreso iberoamericano de estudiantes de ingenieria electrica, [6] COMSOL Multiphysics User’s Guide: Rechargeable Lithium-Ion Battery Version 3.5a, 2008.

29 © Fraunhofer 29 Fraunhofer IKTS:Georg Fauser Adrian Goldberg Diana Leiva Pinzon IAV GmbH Chemnitz: Carolus Grünig Mirko Taubenreuther Daniel Tittel Acknowledgments This work was kindly funded by: Europäische Fond für regionale Entwicklung (EFRE) and the Freistaat Sachsen

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