for Battery Simulation and New Features
Transcript of for Battery Simulation and New Features
xEV simulations require estimates of battery
electrical and thermal behavior.
BDS cell design process.
– Physical cell description
– Fitting model parameters
Model Improvements
– NTGP
– RCRTable
– DISTNP
Conclusions
Overview
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xEV Drive Cycles
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Time (s)
SOC
Speed
D. Prokhorov, Neural Networks, Vol. 21, Issues 2–3, March–April 2008, pp. 458–465
SOC is
relatively
constant but
speed varies
over wide
range.
Speed
(Km/hr)
SOC
All Electric Range Blended Modes
“The drive cycle represents a typical work-home commute which starts in a suburban area,
characterized by UDDS, then continues on a highway, simulated by HWFET, and finally arrives to
downtown urban area, UDDS.” M. Shams-Zahraei et al. J. Power Sources 216 (2012) 237-248
SOC and
speed
vary over
wide
range.
Challenge: Model electrothermal behavior of battery.
Selected Simulation Models in
Battery Design Studio
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(1) J. Newman and W. Tiedemann, J.
Electrochem. Soc. Vol. 140, No. 7, July 1993 pp.
1961-1968.
(2) H. Gu, J. Electrochem. Soc., Vol. 130 No. 7
1983 pp. 1459-1464.
(3) U. S. Kim, Ch.B. Shin, C.-S. Kim, J. Power
Src. 189 (2009) 841-846
(1) T. Fuller, M. Doyle, J. Newman, J.
Electrochem. Soc. 141 (1994) 1-10
(2) Battery Design LLC, “BDS
Documentation”
M. Verbrugge and R. Conell, J.
Electrochem. Soc. 149 (2002) A45-A53
Cell Design
DISTNP
HEV/PHEV Module/Pack
RCR
EV Module/Pack
NTG
Solves transport, kinetics, equations
Quick response for frequent charge/ discharge like HEV/PHEV energy storage
Simple, easy to create model , and best for simple discharging thermal analysis
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BDS Cell Design Process
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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)
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• Button cell
• Active materials
• Additives
• Electrolytes
• Separator
Materials Developers • Model selection
• Electrodes, incl. tabbing
• Separator
• Spiral cylindrical, prismatic, stack
Cell
Designers
• Series/Parallel cells
• CFD with heat transfer
Module/Pack Developers • System
simulation
End Users tbm
tbm
TBM files bridge the
design process for batteries
Battery Design Studio
STAR-CCM+
sim
(tbm)
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Simple Cell – useful for coin cell simulation
Spring
Spacer
Lithium foil, 1.5875 cm dia
Separator, 1.9 cm dia, 100 um
Cathode, 1.27 cm dia
Stainless steel lid
Stainless steel case
1 M LiPF6/EC:DEC (1:1 volume) 7
Materials developers typically use coin cells
Key properties
• Density
• Voltage
• Surface area
• Diffusion coeff.
Fitting solid-phase diffusion coefficient of
lithium nickel cobalt aluminum oxide
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Pulse experiments done in coin cells can be used
to fit solid-phase diffusion coefficients of active
materials.
Y. Li (FMC), Star Global Conference 2012 Amsterdam
Electrolyte Models
- AEM computed property sets from K. Gering
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EC3_EMC7_LiFSI
EC3_EMC7_LiPF6
EC31_PC10_DMC59_LiPF6
EC23_PC21_DMC56_05LiDFOB_05LiPF6
EC32_DEC23_DMC24_EP22_LiPF6
EC38_DMC31_EMC31_05LiPF6_05LiFSI
EC31_EMC46_DEC23_LiFSI
EC31_EMC46_DEC23_LiPF6
EC39_EMC30_DMC30_LiPF6
EC15_EMC64_GBL21_LiFSI
PC58_DME42_LiTFSI
PC58_DME42_LiCF3SO3
Electrolyte properties available in next
release of BDS.
Comparison of Gering’s computed properties
with literature values
L. Valøen and J. Reimers, J. Electrochem. Soc., 152 (5) A882-
A891 (2005)
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EC31_PC10_DMC59_LiPF6
Electrolyte Models
- Tabular Input
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Experimental
values for
electrolyte
properties can
be directly
entered in
tabular form.
Available in BDS 8.02.010
Physical Cell Description: Spirally-Wound Cells
- Edge Collector with clamp
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Available in next release of BDS.
NTG Model
– Parameter Fitting with Bezier Curves
Bezier curves conform to parameter values exactly.
Parameter input is simplified since only values
need to be provided. 17
Comparison of data and fitted
(NTG model) voltage behavior for
cell with 100 micron thick cathode
coating.
Comparison of data and fitted
(NTGP model) voltage behavior for
cell with 100 micron thick cathode
coating.
NTGP model improves fit to data when discharge or
charge capacity depends on rate.
NTGP Model: Peukert Effect
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RCRTable – an enhanced RCR model
Enhancements provided by
RCRTable
• Enter model parameters at
specific SOC values directly, no
need to fit to polynomials
• Use linear interpolation for
temperature dependence
• Polarization resistance can
depend on current (rate or Tafel
effect)
• Warburg impedance
Capability to fine tune fits to data
RCR model is useful for simulating
performance of HEV batteries
• Parameters are a function of
SOC represented by polynomials
• Parameters depend on
temperatures via Arrhenius
relation
M. Verbrugge and R. Conell, J.
Electrochem. Soc. 149 (2002) A45-A53
Rs
Rp
RCR Model
OCV
C=/Rp C=/Rp
Rs
Rp,1 RW
RCRTable Model
OCV
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RCRTable: Rate Dependent Resistance
01
0,1,
exp
1
i
i
i
iRR pp
Current,
A Resistance,
mOhms
50 2.122
100 1.473
Cell resistance decreases with
increasing current
Rp,1 = Polarisation
resistance
Rp,0 = Polarisation
resistance at zero current
i1, i0 = Adjustable
parameters
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RCRTable Model: Warburg Effect
ocd VBdW
Wpp
ee
tAR
RRR
1,
Cell resistance increases with time.
Rp,1 = Polarisation resistance
RW = Warburg impedance
Ad & Bd are coefficients
Voc is related to the OCV curve
C=/Rp
Rs
Rp,1 RW
OCV
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• Sei growth by solvent reduction is one dominant aging mechanism in Li-ion batteries:
• increase in cell resistance • irreversible consumption of available Lithium
• deterioration in: • capacity • rate capability
• experimental investigations have shown a sqrt(t) dependency • a new SEI growth feature was implemented in BDS using a diffusion based transport model after Ploehn et al. (J. Echem. Soc. 151(3) A456 (2004)) • feature available for Li_Pouch_dist1D in release 8.02 but will be available for other Dist models (in STAR CCM+ as well)
Source: arXiv:1210.3672 [physics.chem-ph]a
DISTNP Model: SEI Growth
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M. Inaba, Y. Iriyama, T. Abe, Z. Ogumi, Electrochim. Acta 47 (2002) 1975-1982
Notes on the required input data
Initial SEI thickness specified by user
Values taken from Ploehn paper
Model on or off
Running with the ‘long report’ or ‘solid-phase profiles’ option produces a very large *.pr2 file (circa 2GB in this case)
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Run time is considerably effected by frequency of report in .prg file
Changed to 1 day, which expedites the aging run time and file size
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After simulation is run, ‘aged’ tbm file can be found in the BDS Results directory
Thickness is increased compare to original and this tbm file could then be used in STAR-CCM+ BSM to represent an aged cell
Run a capacity test on both new and aged tbm files to see effect 26
Capacity Fresh
Aged
BDS provides models to simulate electrothermal behavior of batteries useful for design of automotive batteries.
BDS provides pathway for materials suppliers to provide design parameters to cell developers, and cell developers to provide cell models to pack developers.
BDS enables physical cell descriptions that accurately represent actual designs.
New features of BDS
BDS allows modeling of tabbing arrangements for spirally-wound cells.
BDS provides electrolyte property systems to aid in physics-based simulation of lithium-ion cells.
BDS provides accurate representation of parameter dependence for NTG and RCR models on state of charge.
BDS allows simulation of impedance growth to due SEI growth.
Conclusions
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