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