Development of Cell/Pack Level Models for Automotive Li-Ion Batteries with Experimental

Validation Chao-Yang Wang (PI)

Christian Shaffer (Presenter) EC Power

http://www.ecpowergroup.com

6/17/14 Project ID # ES120

This presentation does not contain any proprietary, confidential, or otherwise restricted information

Overview

2

• Start date: 5/1/2011 • End date: 4/30/2014 • Project 97% complete

• Barriers addressed – LiB Performance and Lifetime – LiB Efficiency – LiB Safety – Computer tools for design exploration

• Total project funding: $3.0M – $1.5M (DOE) – $1.5M (cost share) – Fed funds received to date:

$1.276M

Timeline

Budget

Barriers

• Ford • Johnson Controls • Penn State • NREL • ORNL

Partners

Funding provided by Dave Howell of the DOE Vehicle Technologies Program . The activity is managed by Brian Cunningham of Vehicle Technologies. Subcontracted by NREL, Shriram Santhanagopalan Technical Monitor

• Develop an electrochemical/thermal (ECT) coupled model for large-format automotive Li-ion batteries (cells and packs)

• Create a fast & robust tool for realistic geometries • Develop a comprehensive materials database • Integrate ECT3D software with CAEBAT Open Architecture

Standard (OAS) • Aide OEMs and cell/pack developers in accelerating the adoption

of large-format Li-ion technology required for EV & PHEV • Develop a virtual environment to reduce the time required for

design, build and test of Li-ion batteries – Performance – Safety – Life – Efficiency

• Support DOE CAEBAT activity

Project Objectives - Relevance

3

Project Milestones & Activities

4

Recent Milestones Completed M17: Deliver updated software to partners with OAS compatibility

M18: Complete data of electrode potential curves for series of aged cells

M22: Additional data for LFP cathode and LTO anode

M23: Report on experimental data for exchange current density

M24: Report on current and temperature validation

M26 & 27: Report on life model validation

M29: Report on 3-electrode cell experiments for performance and life

Milestones in Progress M25: Final report on software

M28: Deliver final software to partners

M30: Final report on temperature distribution data

M31: Final report on OAS compatibility

M32: Final project report

Approach – Supporting CAEBAT Activity

5

Task 1: Materials Characterization

(PSU)

EC Power software: ECT3D

Task 2: Physico-chemical Models

(ECP)

Task 3: Advanced Algorithms

(ECP)

Task 4: Experimental Validation

(PSU, ECP)

Performance Cycle Life Safety

2.422.222.021.831.631.431.231.030.840.640.44

He

ig

ht

(cm

)

0

2

4

6

8

10

Length (cm)0 50 100 150 200 250 300 350 400 450

Discharge Capacity (Ah)

Cel

lVol

tage

(V)

0 0.2 0.4 0.6 0.8 1 1.2 1.43

3.2

3.4

3.6

3.8

4

4.2

4.4

01000200030005000

Data, Cycled Number

1C discharge

Solid Line: Model Simulation

Ford, JCI Feedback Feedback

Approach – Materials Database

6 Modeling parameters needed at low-T, high-T, wide range of chemical compositions and similar conditions of interest for automotive Li-ion batteries and packs.

Li+

negative electrode positive electrode separator

4M

0.1M

1M

Elec

trol

yte

Conc

entr

atio

n

Electrolyte distribution in a Li-ion cell under discharge

Cathode materials: • NCM • LFP • LMO • LCO

Anode Materials: • Graphite (blended natural/synthetic) • LTO Thousands

of coin cells

• Massive undertaking spanning length of project

• High quality material properties lead to validated results for large format cells and packs

-30°

C 100°

C

Data collected for electrolyte concentrations ranging from 4M to 0.1M

Tested temperature range for materials • Database data acquisition complete

• Active cathode and anode materials given to the left

• Electrolyte

GITT for Ds = f(T,x) EIS for io = f(T,x,ce)

Approach – ECT Model Development

7

Electrochemical Processes - electrochemical reactions - solid state diffusion - ion transport through electrolyte - charge transfer

Thermal Processes

- conservation of thermal energy

Heat generation rate

Temperature-dependent physico-chemical properties

−Φ=Φ Φ

TTRE

ref

actref

11exp ,

Model predictions - potential and current curves - temperature history/distribution - active material utilization - current distribution

( )qT

tTcp +∇⋅∇=

∂∂

λρ

( )

[ ]∑

∑><⋅∇><−

Π+=

k

kkk

jjjnjsjiaq

φ

η

i

• Understanding thermal phenomena & thermal control

has huge impact on – Battery safety – Cycle life – Battery management system – Cost

• Electrochemical-thermal (ECT) coupling required for

– Safety simulations – Thermal runaway – High power, low-T operation – Heating from subzero environment

• Completed data acquisition for materials database • Validated efficient, electrochemical-thermal (ECT)

coupled large-format cell simulation – Performance and active materials utilization

• Validated temperature- and design-dependent life model – LFP/graphite and NMC/graphite – User-defined load profile and thermal conditions

• Validated safety model • ECT-coupled pack model • Demonstrated co-simulation with OAS • Software commercially available

Technical Accomplishments

8

Accomplishments – Validation/Performance

9

Segmented pouch cell

In-situ Current Distribution

1-positive-tab-counter W. Zhao et al. J. Power Sources 257 70-79 (2014)

Direct measurement and validation of in-situ current density of a large-format Li-ion battery; ensuring current uniformity is critical for utilization of active material, directly effecting energy density (up to 50%)

Zhang, et al., JES, 160 A2299-A2305 (2013)

Time-averaged CD Non-uniformity Factor

Counter-located

Co-located

(+)

(-)

Counter-locatedtab

(-)

(+) Co-locatedtab

At End of Discharge

Accomplishments – Validation/Performance

10

Effects of Ambient Temperature In-situ Temperature Distribution

Direct measurement and validation of in-situ temperature distribution

Distribution Over Radius

∆T < 5oC in radial direction at 3C @ end of discharge

• In-situ temperature measurement within Li-ion battery

• Data acquired over wide-ranging temperature, C-rate, and thermal boundary conditions

• Validation ongoing

0

0.05

0.1

0.15

0.2

0 500 1000 1500 2000

Frac

tiona

l Cap

acity

Los

s (@

1C)

Cycle Number

Accomplishments – Validation/Life

11 11 On-field relevant life cycling of commercial Li-ion cells successfully captured with model at different temperatures; all life models are mechanism-based and valid under wide operating conditions without calibration

Capacity (mAh)

Volta

ge(V

)

0 500 1000 1500 2000 2500

2.6

2.8

3

3.2

3.4

3.6

0136912 (4598 cyc)

Month

1C CC cycling at 25°C

C/10 discharge test at

(symbols are experimental data)

Capacity (mAh)

Volta

ge(V

)

0 500 1000 1500 2000 2500

2.6

2.8

3

3.2

3.4

3.6

0136912 (5017 cyc)

Month

1C CC cycling at 45°C

C/10 discharge test at

(symbols are experimental data)

25°

C

45°

C

A123 ANR26650M1-B: Graphite-LFP high power cell Data from Safari & Delacourt, JES, 258(5) A562, 2011

• On-field relevant cycling at 25°

C • Commercial LFP/graphite cell • Internal life data

Complex Cycling at Room Temperature CC Cycling @ 25oC and 45oC

-20

-10

0

10

20

30

0 2000 4000 6000

C-Ra

te

Time (s)

Commercial LFP/Graphite Cells

Accomplishments –Validation/Life

12 Degradation mechanisms in each electrode validated using 3-electrode cell

NMC/Graphite Cells

For reference electrode

Negative terminal

Electrolyte chamber

O-ring seals

Battery

O-ring seal

Positive terminal

For reference electrode

Negative terminal

Electrolyte chamber

O-ring seals

Battery

O-ring seal

Positive terminal

For reference electrodeFor reference electrode

Negative terminalNegative terminal

Electrolyte chamberElectrolyte chamber

O-ring sealsO-ring seals

BatteryBattery

O-ring sealO-ring seal

Positive terminalPositive terminal

Capacity (mAh)

Cel

lVol

tage

(V)

Tem

pera

ture

(°C

)

0 200 400 600 800 1000 12001.5

2

2.5

3

3.5

4

30

40

50

60

01000200030004000

50°C 5C cycling

25°C 5C characterization

Full cell characterization at 5C, 25oC

Capacity (mAh)

Ano

dePo

tent

ialv

sLi

/Li+

(V)

0 200 400 600 800 1000 12000

0.1

0.2

0.3

0.4

0.5

01000200030004000

50°C 5C cycling

25°C 5C characterization

Anode at 5C Capacity (mAh)

Cat

hode

Pote

ntia

lvs

Li/L

i+(V

)

0 200 400 600 800 1000 12002.5

3

3.5

4

4.5

01000200030004000

50°C 5C cycling

25°C 5C characterization

Cathode at 5C

• CC cycling at 50°

C, 5C-rate • NMC/graphite cell • In-house data obtained using

3-electrode cell • Use of individual electrode potentials

for more rigorous validation of life mechanisms in models

Accomplishments – Safety/Validation

13

0.00E+00

0 100 200 300

Curr

ent

time (s)

0.00

0 100 200 300

Volta

ge

time (s)

0.00

0 100 200 300

Tem

pera

ture

time (s)

Commercial Cell External Short

• External short of one cell within commercial pack

• Dimensionless current, voltage, and temperature data shown on the left

• Good agreement between data and simulation (temperature within ~ 10%)

• Maximum temperature reached during shorting process can be used to assess safety of design

Software developed can be used to assess the safety of commercial large-format batteries

Accomplishments – Safety

14 ECT3D is used routinely for safety evaluation of large-format cells and safety-conscious designs

• Software gives coupled electrochemical-thermal response of the cells during nail penetration events

• Time scale and locality of heating dictate ability of safety designs to maintain cell safety • 5mm nail: short time scale, local heating • 20mm nail: long time scale global heating

Safety Simulations in ECT3D

Maximum Temperature During Nail Penetration

TPC

Nail Penetration with Coated Phase-change (PC) Material

Physics of Shorting During Nail Penetration

5Ah NMC/Gr. Cell; 5mm nail

5Ah NMC/Gr. Cell; 20mm nail

Accomplishments – Other

15 Other routine uses of software: pack thermal management design, safety evaluation of large-format cells and safety-conscious designs, and designing batteries with optimal power and energy tradeoff

Cell Voltage (V)

ASI(Ω

cm2 )

2.8 3 3.2 3.4 3.6 3.8 4 4.2 4.40

20

40

60

NCM75% LFP25%NCM100%

Discharge Capacity (mAh)

Cel

lVol

tage

(V)

Tem

pera

ture

(°C

)

0 500 1000 1500 20002

2.5

3

3.5

4

20

40

60

80

100

120

0.1C1C3C5C

NCM75% LFP25%

Similar results shown in literature: Gallagher et al. JPS 196 (2011) 9702-9707

Mixed Electrode Model

• Above example shows mixed electrode model used to improve low SOC power via blended NMC/LFP mixture

Baseline Rshort Rshort = 4xRBL

Cell Internal Shorting

-10

0

10

20

30

0.8

0.9

1

1.1

1.2

0 1000 2000 3000

Cel

l Tem

p (°

C)

C-R

ate

Time (s)

Thermally-coupled Pack Modeling

Design of pack thermal management

Accomplishments – OAS

16

OAS Wrapper ECT3D

Dakota

Start

End OAS Wrapper

2.9

2.92

2.94

2.96

2.98

3

3.02

3.04

1 1.5 2 2.5

Puls

e Po

wer

Den

sity

(kW

/L)

Cathode Loading (mAh/cm2)C

urre

nt

Pow

er

ECT3D has been successfully coupled to other software via OAS

ECT3D Coupled to Dakota Using OAS • ECT3D successfully coupled to

Dakota optimization software via OAS

• Design optimization demonstrated below

• ECT3D can be coupled to other softwares (e.g. industry internal or other 3rd party) via OAS

0

0.2

0.4

0.6

0.8

1

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.0 1.5 2.0 2.5

ε(-)

Nor

mal

ized

Rxn.

Are

a

Cathode Loading (mAh/cm2)

ECT3D

Dakota OAS

Input: Design Parameterization Output: Optimized Cell

Accomplishments – Publications

17

– Wei Zhao, C.Y. Wang, Gang Luo, Christian E. Shaffer, “New Findings on Large Li-ion Battery Safety through Computer Simulation”, Battery Safety 2011- Advancements in System Design, Integration, & Testing for Safety & Reliability, November 9-10, 2011, Las Vegas, NV

– G. Luo and C.Y. Wang, A Multi-dimensional, Electrochemical-Thermal Coupled Li-ion Battery Model, Chap.6 in Lithium-Ion Batteries: Advanced Materials and Technologies, CRC Press, 2012.

– Yang, Xiao Guang, Miller, Ted and Yu, Paul, Ford Motor Company, “Li-Ion Electrochemical Model,” 2012 Automotive Simulation World Congress, October 30-31, 2012, Detroit, MI

– Shaffer, C.E., Wang, C.Y., Luo, G. and Zhao, W., “Safety Analysis Design of Lithium-ion Battery EV Pack through Computer Simulation,” Battery Safety 2012, Knowledge Foundation Conference, December 6-7, 2012, Las Vegas, NV

– Shaffer, C.E. and Wang, C.Y., “Thermal Management for Start-up of Li-Ion Batteries,” 222nd Meeting of The Electrochemical Society (PRiME 2012), Honolulu, HI, October 7-12, 2012

– Luo, Gang, Shaffer, C.E. and Wang C.Y., “Electrochemical-thermal Coupled Modeling for Battery Pack Design,” 222nd Meeting of The Electrochemical Society (PRiME 2012), Honolulu, HI, October 7-12, 2012

– Kalupson, J., Luo, G. and Shaffer, C., “AutoLion™: A Thermally Coupled Simulation Tool for Automotive Li-ion Batteries,” SAE Technical Paper 2013-01-1522, 2013, doi: 10.4271/2013-01-1522. SAE International World Congress and Exhibition, April 16, 2013, Detroit, MI

– Ji, Y., Zhang, Y., and Wang, C.Y. (2013). “Li-Ion operation at low temperatures,” Journal of the Electrochemical Society, 160(4), A636-A649

– Zhang, G., Shaffer, C. E., Wang, C. Y., & Rahn, C. D. (2013). “In-situ measurement of current distribution in a li-ion cell,” Journal of the Electrochemical Society, 160(4), A610-A615

– Ji, Y., Wang, C.Y. (2013). “Heating strategies for Li-ion batteries operated from subzero temperatures,” Electrochimica Acta, 107, 664-674

– Guangsheng Zhang, Christian E. Shaffer, Chao-Yang Wang, and Christopher D. Rahn, “Effects of Non-uniform Current Distribution on Energy Density of Li-ion Cells,” Journal of the Electrochemical Society, 160 A2299-A2305 (2013)

– G.S. Zhang, L. Cao, S. Ge, C.Y. Wang, C. E. Shaffer, C. D. Rahn, In Situ Measurement of Li-Ion Battery Internal Temperature, 224th ECS Meeting, Abstract #538, San Francisco, CA, USA, Oct. 27 - Nov. 01, 2013

– W. Zhao, G. Luo, and C.Y. Wang, “Effect of Tab Design on Large-format Li-ion Cell Performance,” Journal of Power Sources 257 70-79 (2014)

– G.S. Zhang, L. Cao, S. Ge, C.Y. Wang, C. E. Shaffer, C. D. Rahn, “In Situ Measurement of Temperature Distribution in a Cylindrical Li-ion Cell,” to be submitted (2014)

– W. Zhao, G. Luo and CY Wang, “Modeling Nail Penetration Process in Large-Format Li-ion Cells,” submitted to J power sources (2014)

Collaboration w/Other Institutions

18

Project Lead – Software development and sales, project administration.

Funding Agency

CAEBAT Program Administrator

Industrial Partner – testing, validation, and feedback

Industrial Partner – testing, validation, and feedback

Academic Partner – materials testing and

detailed model validation

Open Architecture Software

• Wrap up final deliverables for this project – M25: Final report on software – M28: Deliver final software to partners – M30: Final report on temperature distribution data – M31: Final report on OAS compatibility – M32: Final project report

• Outside of this project – Pack-level safety – Abuse simulation – Refined life models

Future Work

19

• Last year’s review did not include an individual presentation from our team (CAEBAT overall project presentation/review was given by NREL)

Response to Previous Year Review

20

• All main project goals have been met – Development of ECT-coupled cell and pack model – Materials database for commercially relevant materials, accurate over wide-

ranging T, ce, SOC, etc. – Validated prediction of performance and active material utilization – Validated safety models – Validated life models

• Commercial partners (Ford, JCI) – Have been using updated models in-house for several years – Have given invaluable feedback and helped validate model

• Software is commercially available • Meeting CAEBAT/DOE goals

– Helping to accelerate the adoption of automotive Li-ion battery cells & packs

– Enabling technology for EV, PHEV

Summary

21