Battery Design Studio Update

Transcription

1 Advanced Thermal Modeling of Batteries Battery Design Studio Update March 20, :30 13:55

2 New Features Covered Today 3D models Voltage dependent diffusion Let s start with brief introduction to Battery Design Studio

3 Battery Design Studio A user-friendly interface between battery designers and users for costing, sizing, and correlation of test data to performance, safety, and life predictions. User interface Input Output Development started APR1999 Lab Model Data Size Cost Power Impedance Life Abuse, etc Page 3

4 Standardized software promotes (enables) communication Exchange of battery information. Input Materials Supplier Battery Design Studio Formulations Cell Design Test conditions Output Output Models Input Input Output Output Battery Developer Input Modeler Modeler Standardization lowers cost, allows faster product introduction.

5 BDS Cell Design Process Physical Cell Description Coin, cylindrical pouch, prismatic Gives size, weight, equilibrium voltage, capacity, bill of materials, etc. Fit Model Parameters circuit, physics Allows simulation of performance Use and/or Distribute Text Battery Model (TBM) Page 5

6 TBM files bridge the supply chain of batteries TBM file Button cell Formulations Test results Materials Developer (cathode, anode, separator, electrolyte, etc.) Cell Designer Model selection Electrodes, incl. tabbing Separator Cylindrical, prismatic, pouch STAR-CCM+ Performance estimation Model selection Series/Parallel cells Cooling End User, Module and/or Pack Developer TBM file, prg, out Page 6

7 3D MODEL THEORY

8 Unit Cell Concept Negative current collector Positive current collector Unit Cell Material between current collectors represented as unit cell. Collectors modeled as resistors connecting unit cells. Page 8

9 Selected Simulation Models in Battery Design Studio Cell Design DISTNP (1) T. Fuller, M. Doyle, J. Newman, J. Electrochem. Soc. 141 (1994) 1-10 (2), BDS Documentation Solves transport, kinetics, equations HEV/PHEV Module/Pack RCR M. Verbrugge and R. Conell, J. Electrochem. Soc. 149 (2002) A45-A53 Quick response for frequent charge/ discharge like HEV/PHEV energy storage J Y V U a a 0 4 p 5 2 DOD a2 DOD a3 DOD DOD a DOD 2 1 Y a a EV Module/Pack V U n NTG (1) J. Newman and W. Tiedemann, J. Electrochem. Soc. Vol. 140, No. 7, July 1993 pp (2) H. Gu, J. Electrochem. Soc., Vol. 130 No pp (3) U. S. Kim, Ch.B. Shin, C.-S. Kim, J. Power Src. 189 (2009) Simple, easy to create model, and best for simple discharging thermal analysis 6 3 Page 9

10 3D CELL DESIGNS

11 Stacked Plate Design Page 11

12 Stacked Plate Design Page 12

13 Spirally Wound Design Page 13

14 18650 LoY, Pos Plate Voltage Page 14

15 18650 LoY, Pos Inner Current Density Page 15

16 18650 LoY, Outer Current Density Page 16

17 18650 LoY, Neg Plate Voltage Page 17

18 18650 LoY, Neg Plate Iin Page 18

19 18650 LoY, Neg Plate Iout Page 19

20 CONCENTRATION-DEPENDENT DIFFUSION COEFFICIENTS

21 Concentration-dependent diffusion coefficients Solid-phase diffusion coefficients are known to depend on concentration. Theory shows that diffusion coefficient depends on derivative of equilibrium potential (E) with respect to lithium fraction (x). ~ D Li D Li d d ln ln a x D Li Fx RT Correction can be significant. de dx BDS accounts for this correction. Concentration dependence of lithium diffusion coefficient in LiCoO 2, Young-Il Jang, Bernd J. Neudecker, and Nancy J. Dudney, Electrochemical and Solid-State Letters, 4 (6) A74-A77 (2001) Page 21

22 Accounting for concentration dependence of solid-phase diffusion coefficients in BDS (1) Use Monotonic cubic mode for interpolation of voltage data. Page 22

23 Accounting for concentration dependence of solid-phase diffusion coefficients in BDS (2) Just check option for Diffusion Conc. Correction Page 23

24 Example: NCM/Graphite Cell NCM Equilibrium Curve Graphite Equilibrium Curve E x de dx x Cathode material shows significant effect of voltage on solid-phase diffusion coefficient. Page 24

25 Simulation Results: Discharge Curves ~80 mv delta ~8.4% capacity delta ~40 mv delta ~2.5% capacity delta ~20 mv delta ~0.6% capacity delta Effect of variability in solid-phase diffusion coefficient becomes more significant at higher rates. Page 25

26 Simulation Results: Diffusion Coefficient Variation across cell for 3C Discharge Constant Diffusion Coefficient Variable Diffusion Coefficient Time, min Solid-phase diffusion coefficient has complex profile when concentration dependence is accounted for. Distance from negative collector, mm Page 26

27 Simulation Results: Solid-Phase Concentration Variation across cell for 3C Discharge Negative Positive Variable Diffusion Coefficient Surface concentration Constant Diffusion Coefficient Average concentration Distance from negative collector, mm Variable diffusion case results gives smaller concentration gradient in positive electrode. Page 27

28 Summary Dependence of solid-phase diffusion coefficient with lithium concentration has a strong theoretical foundation, and experimental validation. Accounting for concentration dependence of solid-phase diffusion coefficients has a significant effect of cell behavior at high rates. BDS allows this effect to be simulated with ease. Page 28

29 Conclusion Battery Design Studio is the industry standard platform for: Analyzing data and visualizing results. Exchanging battery data and models. Pathway to pack and system design with STAR-CCM+. Page 29