Thermal & Electrochemical Simulation of Battery Pack Systems
Steve HartridgeDirector, Electric & Hybrid Vehicles
Micro-structure Electrochemistry• Virtually test SEM produced electrode geometry• Conduct design studies on new concepts
Provides previously unseen spatial effects within electrodes“Design” next generation electrodes
CD-adapco Battery Modeling Technology
Cell Design Tool• Build physics based models of electrode pairs and
couple them to the cells physical construction• Use the provided database of materials to
construct virtual cells and test their performance
Overall System Design• Interface Module &
Pack analyses with complex power train system models
• Embed physics based or empirical models in to power train systems models
Module & Pack Analysis• Flow, thermal & Electrochemistry analysis of
complex power systems• Study detailed spatial effects at cell, module &
pack level
Pouch
Battery
A genuinely unique tool which predicts the spatial distribution of ions and potential within an arbitrary, multi-phase microstructure region– Electric Potential in solid and electrolyte regions– Salt concentration in electrolyte– Concentration of Li in active parts of electrodeUses the arbitrary geometry handling power and massively parallel architecture of STAR-CCM+Easy set up of the initial states of the electrode based on OCV and state of charge
“Primary use is the design of next generation battery electrodes”
Micro-structure Electrochemistry
A VARTA LIC 18650 WC LiCO2 battery was segmented by FIB-SEM and reconstructed**. A 21 million cell finite volume mesh was created including active material, secondary conductive phase and electrolyte fluid phase*.
“Primary use is the design of next generation battery electrodes”
Micro-structure Electrochemistry – Case Study
*Presented at Solid State Electrochemistry Workshop 2013 held at Heidelberg**Hutzenlaub et al. 2012 Three-Dimensional model development for lithium intercalation electrodes, J. Power Sources 185(2)Three-dimensional electrochemical Li-ion battery modelling featuring a focused ion-beam scanning electron microscopy based three-phase reconstruction of a LiCoO2 cathode, Hutzenlaub et.al. Electrochimica Acta - 2014
A design study using DEM
“Primary use is the design of next generation battery electrodes”
Micro-structure Electrochemistry – Case Study
Binders
Active Material
3 Phases Problem
Use STAR-CCM+ CAD tool to
improve binder’s network realism
A comprehensive design environment which links a physics based electrochemistry model with a sizing program, enabling the electrochemical and physical design of a cell to be studied– Electrochemistry model – numerous derivatives with increasing fidelity– Sizing program – Numerically ‘build’ the cell and understand important
metrics
Covers all Battery form factors – Stack, wound prismatic & wound cylindricalParameterization of a battery cell – creating either an contemporary electrochemistry model or equivalent circuit model
Example Model
Cell Design Tool
Sizing Example – Cylindrical Cell– Default High Power NCA/Graphite 18650 cell, 1.04 Ahr,
– Increased Energy NCA/Graphite 18650 cell, 1.28 Ahr(23% up)
Cell Design Tool
Discharge Response– Sanyo LiNi0.33Mn0.33Co0.33O2 18650 cell (2.05Ahr)– Cells disassembled and physically characterized – C/5 to 2C discharge rate
– Errors within 6.5% over total discharge– Errors within 2.8% over 60% SOC window
Cell Design Tool – Validation Result
Sakti, et. Al, A validation study of lithium-ion cell constant c-rate discharge simulation with Battery Design Studio, International Journal of Energy Research 2012
Cell Design Tool - Validation Result
Figure shows the prediction of cell voltage using a detailed electrochemical model, over a complete drive cycle. The lower graph compares simulation (red line) with experimental (green points) result. The upper graph is the instantaneous error between the two lines . Average prediction error over the 30 minute drive cycle is 8mVThanks to Dave Howell, DoE for their co-funding of the CD-adapco CAEBAT project and NREL for their project involvement
Cell Description– Geometric Description of cell– Material properties of coatings– Voltage vs. Stoichiometry for active– Electrolyte selection
Cell Design Tool – Process
Cell Calibration Data– OCV curve– HPPC tests at differing rates/differing temperatures– Constant current at low C rate/differing temperatures
Cell Parameter Estimation– Stoichiometry at formation to match capacity– Temperature dependent diffusion co-eff– Kinetic rate constant– SEI resistance to match voltage drop in HPPC test
Cell Validation
• Created a 20Ah cell with LiFePo cathode/Graphite anode• Run a 1 year aging simulation
• Compare “Initial” with “aged” cell performance
Cell Design Tool – Aging Prediction
Solvent Diffusion Model for aging of lithium-ion battery cells, H. P loehn, P. Ramadass, R. White. J Electrochemistry Soc. 151 (3) A456-A462 (2004)
Cell Design Tool > Module & Pack Analysis
Cell Design Tool• Build physics based models of electrode pairs and couple
them to the cells physical construction• Use the provided database of materials to construct
virtual cells and test their performance
Module & Pack Analysis• Flow, thermal & Electrochemistry analysis of
complex power systems• Study detailed spatial effects at cell, module &
pack level
Electrochemist/Cell Designer
Thermal Analyst/application expert
Materials DatabasePouch
Prismatic
InputProgram:Drive Cylce, Discharge (Current, Power,etc)
Model Parameters:Properties + Experiments
OutputSOC (%)Voltage (V)Heat Generation (W)
Concentration Solid Diffusion Coefficient (m2/s)Etc…
Module & Pack AnalysisCoupled Physics
Pouch CylindricalPrismatic
Thermal/Fluidic Solver
Equivalent Circuit
Or Physics Based
Elec
troC
hem
ical
Solv
er
Battery Heat Battery Temperature
Cooling Plates
Pouch LCO cells
Compression Pads
Tab Connector
21 Ahr LCO – 3.8V Nominal VoltageOpposite Tab DesignLiquid CoolingPerformance Prediction:RCR Model
Module & Pack Analysis
Periodicity Applied
US06 Charge Depleting Drive Cycle
Cur
rent
(A)
Flow
rate
(kg/
s)
120
-80
0.002
0
Cooling Channels Flow Rate
Time (s)
Time (s)0
0
600
600
Conditions
Current Density in Tab Connectors (A/m2)
Module & Pack Analysis
German Autos OEM Project (Daimler, Porsche & GM Europe) managed by ASCS, Stuttgart– 84 cell off-road hybrid pack– Liquid cooled cold plate thermal control– Equivalent circuit cell model– Transient electrical/thermal boundary conditions
Li-ion battery simulation strategies and validated implementations for the virtual development process of electrified vehiclesS. Fell, E. Schneider, M. Lindner, R. Immel, J. KremserSIMVEC – Berechnung, Simulation und Erprobung im Fahrzeugbau 2012, VDI-Berichte2169, p.241-254; ISSN 0083-5560, ISBN 978-3-18-092169-3; VDI Verlag GmbH, Düsseldorf 2012
Pack Voltage
Cell Temperatures
Left Side –with weak cell
Right side – all strong cells
Current shows <20 Amps provided by
“weak” side
“Weak” cell runs hotter
Module & Pack Analysis – Weak Cell
Overall System Design
Link to system design software– Matlab Simulink
• Link available at cell or module/pack level• Embed certain cell models in to Simulink directly
– AMESim• Link available at cell or module/pack level
Equivalent Circuit
Or Physics Based
Elec
troC
hem
ical
Solv
er
Inputs
Outputs
Nissan – Star Global Conference 2012FMC – Star Global Conference 2012GM Europe – Star Global Conference 2012Hitachi Maxell – Japanese Conference 2012Hyundai Mobis – Korean Conference 2012Carnegie Mellon - INTERNATIONAL JOURNAL OF ENERGY RESEARCH
+ many users worldwide that are not named
Department of Energy– Co-funded project with JCI & A123– $3M project– Software now available
Wide spread adoption of CD-adapco battery modeling methods
Battery Simulation Industry Presenters
Conclusions
CD-adapco’s Battery Solution is a Multi-physics and Multi-scales solution offering performance simulation of coupled systems involving Li-ion batteries.Predicts the performance of a new cell and an aged or aging cellCurrent development focuses on abuse conditions such as thermal runaway caused by nail penetration, internal or external short circuits
Development also focuses on other aging mechanisms
Visit the company’s website: http://www.cd-adapco.com/industries/batteries
Current Temperature