An Overview of Battery Simulation Robert Spotnitz, Battery Design - - PowerPoint PPT Presentation

An Overview

• f

Battery Simulation

Robert Spotnitz, Battery Design LLC

Overview

• A. Battery History
• B. Battery Market and Technology
• C. Battery Modeling

2

What is a battery?

• A battery or “galvanic cell” converts

chemical energy to electrochemical energy using at least one of reactant stored in a cell.

• A fuel cell converts chemical energy to

electrochemical energy using reactants stored externally.

• A capacitor stores and releases electrical

energy using double-layer charge separation or a pseudo-capacitive effect such as surface adsorption, reaction or bulk intercalation.

Volta’s pile Ag/Zn (1800)

3

4

Terminology

OH-

Zn ZnO

e- 

Ag2O 2Ag

e- Battery consists of one or more cells Cell consists of a pair of electrodes and an ion conductor Electrode consists of active material, current collector, and tab Positive electrode is called “cathode” Negative electrode is called “anode” Package, separator, insulators, etc. ionic conductor

e-  e- 

 

    e O H ZnO OH Zn 2 2

2  

    OH Ag e O H O Ag 2 2 2

2 2

ZnO Ag Zn O Ag    2

2

1959: Alkaline 1991: Li Ion 1958: Organic Li primary 1947: O2 Recomb. Ni/Cd

5

1980s: NiMH

1866: Dry cell 1860: Pb Acid 1800: Volta invents battery

1962: Newman and Tobias, Porous Electrode Theory 1994: Doyle, Fuller, Newman, DUAL model Li Ion 2005: Garcia et al., microstructural model

1905: Nernst Equation: G=-nFE 1887: Peukert’s Law: Iptd=constant 1834: Faraday’s law of electrolysis

1930: Butler-Volmer Eqn

                    RT RT i i

c a

• 

   exp exp

Battery Market

Only a few chemistries dominate market Rechargeable

• Pb Acid
• Lithium Ion

Primary or single discharge

• Alkaline

@ $60/battery ~$8 Billions

North American Lead Acid SLI Battery Forecast

7

• C. Pillot, Batteries 2009, Avicenne

Worldwide Rechargeable Battery Sales Excluding Lead Acid

8

Lithium Ion NiCd NiMH

Lithium-ion dominates market for portable electronics. by application

Li-Ion Cell World Market Size & Forecast ($Billions)

• S. Inagaki, Yano Research Institute, SAE Intl. Vehicle Battery Summit, Shangahi 2011

Consumer Industrial Automotive Other

35 30 25 20 15 10 5 conversion used $1 = 100 Yen Consumer - phones, computers, cameras, etc. Other - power tools, e-bikes, medical, aerospace Industrial - smart-grid, residential, UPS Automotive - passenger vehicles excluding bus, railroad

Huge growth in lithium-ion market is forecast for vehicles

9

Battery Requirements: Consumer Products

• Consumer

electronics

– high volumetric energy density – low cost – 1 year life – Safety

• Power tools

– high power density – low cost – 2-3 year life – safety

10

Largest market and growing.

• Trends

– longer calendar life – higher energy density

Battery Requirements: Hybrid Electric Vehicles

• High Power (> 1

kW/kg)

• Low cost
• 8+ year life
• Abuse tolerance

Typical is ~1 kWh systems capable of providing ~25 kW

11

Nickel metal hydride batteries dominate but lithium-ion is projected to win out by providing smaller, lower cost packs

Battery Requirements: Battery Electric Vehicles

• High gravimetric

energy density (>100 Wh/kg)

• Very low cost
• 8+ year life
• Abuse tolerance

Typical is 24 kWh systems capable of providing ~50 kW

12

Lithium-ion is currently only viable chemistry with sufficient energy density for this application.

Battery Requirements: Grid Regulation

• High power, fast

response (seconds)

• Cost? Life? Abuse?

13

Market is potentially larger than automotive, but large uncertainty as to economic feasibility.

Lead Acid (Valve Regulated) - Actives and Separator

2 4 3

2.3 10 45% cm a cm    

Sep ~95% porous, ~1.3 mm thick

Charged Discharged

• D. Pavlov, V. Iliev, J. Power Src / 7 (1981) 153.
• J. H. Yan et al. , J. Power Src. 133 (2004)

135-140.

Negative ~ 2 mm thick Positive ~ 2 mm thick

2 5 3

2.3 10 40% cm a cm    

Lead-acid electrochemistry is very complex. Pb + H2SO4  PbSO4 + 2e + 2H+ PbO2 + 2e +2H+ + 2H2SO4  PbSO4 + 2H2O

Li-ion Cell Cross-Section

• Z. G. Li et al. J. Electrochem. Soc., 150 (9) A1171 (2003)

15

Lithium ion battery operation is relatively simple. LiC6  Li+ + e + C6 Li+ + e + Mn2O4  LiMn2O4

Typical Lead-Acid Battery

DOE-HDBK-1084-95 September 1995

16

Spirally-Wound Cells

17

Tesla Powertrain Technology

• K. Kelty, 26th Intl. Battery Sem., Ft. Lauderdale, Fl, 2009

Small Cells 18650

18

Mitsubishi iMiEV Battery

22 modules (4 cells/module)

19

• 2011 World Markets for Batteries

– Primary

• estimated at ~$4 Billions for alkaline and ~$1.5 billions for others

– Rechargeable

• lead acid ~$20 Billions
• lithium ion ~$12 Billions
• nickel metal hydride ~$1.5 Billions
• Automotive market is growing rapidly and is amenable

to design

• Opportunities for

– design tools for batteries – prediction of life and abuse tolerance

Summary

20

Overview

• A. Battery History
• B. Battery Market
• C. Battery Modeling

21

Battery Modeling

• Concept of Electroactive Species
• Concept of Exchange Current Density
• Battery Equations and Modeling Approaches

22

+ 

1



Nernst Equation

2



 

2 3

ln

2 1

 

    

Fe Fe

• c

c RT G F  

23

Can compute voltage based on chemistry.

+ 

1



2



Nernst Equation

 

2 3

ln

2 1

 

    

Fe Fe

• c

c RT G F  

24

Can compute voltage based on chemistry.

 

           



 

RT c k i Fe e Fe

c Fe

• f

f 2 1 , 2 3

exp

3

  

 

         



 

RT c k i e Fe Fe

a Fe

• b

b 2 1 , 3 2

exp

2

  

1



2



+ 

25

b f net

i i i  

Butler-Volmer Equation Can compute reaction rates.

1



2



 

           



 

RT c k i Fe e Fe

c Fe

• f

f 2 1 , 2 3

exp

3

  

 

         



 

RT c k i e Fe Fe

a Fe

• b

b 2 1 , 3 2

exp

2

  

+ 

b f net

i i i  

Butler-Volmer Equation

26

Can compute reaction rates.

2

, 1 PbO



2



Pb , 1



2



O H PbSO Pb SO H PbO

2 4 4 2 2

2 2 2    

Lead Acid Battery

27

2

, 1 PbO



2



Pb , 1



2



O H PbSO PbO SO H Pb

2 4 2 4 2

2 2 2    

28

2

, 1 PbO



2



Pb , 1



2



 

c D t c      

 

S T k t T cp       

 

 

x T x

E        X X I 2 1

*

Eulerian strain

 

v        t

j Poisson   

1 2



1 1

'     i Law s Ohm

 i1

   

                   





RT k RT c k j e PbSO SO Pb

c a Pb a SO a Pb 2 1 , 2 1 , 4 2 4

exp exp 2

2 4

     

   

                     



RT c k RT k j SO O H PbSO e SO H PbO

c SO H c PbO a a PbO 2 1 2 , 2 1 , 2 4 2 4 4 2 2

exp exp 2 2 2

4 2 2 2

     

j  j 

 

a t F RT i

• ln

2 1

2 2

     



  

i2 

29

Macro-Homogeneous Modeling

Negative Electrode Positive Electrode Separator

L r

2 2

L r 

• J. Newman, C. Tobias, “Theoretical Analysis of

Current Distribution in Porous Electrodes,” J. Echem. Soc., 109,1183 (1962)

Phenomena included in macro- homogeneous battery models (partial)

• multi-component electrolytes
• precipitation
• side reactions
• particle size distribution
• mixtures of active materials
• expansion/contraction of

particles

• convection
• current distribution along

collectors

• local heat generation
• stress generation

30

Unit Cell Full Cell Module/Pack Vehicle

Hierarchy of Battery Simulation

31

Hierarchy enables higher level models to be built on lower level models.

STAR-CCM+

C

BD

Macro-homogeneous models

Some questions answered:

• What limits performance?

– diffusion, kinetics, ohmic

• What is optimal grid design?
• How thick/porous should

electrode/separator be?

• What is optimal electrolyte

concentration?

• How much heat does the cell

generate? Need to calibrate model against actual cell

• tortuosities
• kinetics
• paste conductivity
• contact resistances

Some outstanding questions:

• What is optimal mix of binder,

conductivity aid, active material?

– what is porosity, conductivity of a blend?

• What are kinetic parameters?
• What is contact resistance

between paste and grid?

• What are physical properties such

as diffusion coefficients?

• How does battery fade over

time?

• Microstructural modeling
• Atomistic modeling

32

CD-adapco’s Microstructural Model

This approach provides the most realistic model of a battery and is attracting interest of battery researchers worldwide. This tool is useful for calibrating conventional macro-homogeneous models and designing microstructures.

33

Boris Kaludercic Christian Walchshofer Milovan Perić Gaëtan Damblanc Steve Hartridge Robert Spotnitz

Summary

• Physical processes involved in battery include

– electrochemistry – phase change – shape change – current and potential distributions in multiple phases – diffusion and migration – convective fluid flow (gas and liquid) – heat transfer

• To-date, most successful approach is based on

volume averaging (macro-homogenous)

• Microstructural modeling promise to address

major questions in battery design

34

BACKUP

35

Battery Design Tools

Battery Design Process

Expert Analysis Build Pack Test Pack Reqmts Met?

Reqmts

Done

yes no design pack

Build Pack Test Pack

design pack

Reqmts Met? Analyze

no yes In software

Assess Reqmts

37

Battery Testing

Small consumer cells

• typically ~1-10 Wh/cell

($0.25-2.5), 1-90 Wh/pack ($0.25-22.5)

• typically 300 cycles, if 4

hours/cycle, then ~1.7 months/test

• 9 – 12 month warranty
• abuse testing required for

shipping (UN, DOT) Large automotive

• typically ~10-500 Wh/cell

($0.25-, 1-10 kWh/module, 1-60 kWh/pack

• typically >1000 deep cycles,

if 4 hours/cycle, then 5.5 months/test

• 8-10 year warranty
• abuse testing required for

shipping (UN, DOT)

38

Battery Test Equipment

Small cell testing ~$200/channel example: 96 channel Series 4000 Large cell/pack testing ~$50K/channel example: 2 channel ABC-150

39

Motivation for Simulation

Methodology for system design

• Cooling system
• Vehicle

Reduce development time/cost

• Case studies in software to

eliminate testing

Improve design

• Explore larger parameter

space for pack, module, cell

40

Unit Cell Full Cell Module/Pack Vehicle

Hierarchy of Battery Simulation

41

Hierarchy enables higher level models to be built on lower level models.

Software Tools for Battery Design

• BDS and STAR-CCM+ BSM
• Comsol Multiphysics
• Fluent, Matlab, others (EC Power, Fortran

codes, Excel spreadsheets)

42

From cell to system design

• Button cell
• Formulations
• Test results

Materials Developer (cathode, anode, separator, electrolyte, etc.)

• Model selection
• Electrodes, incl. tabbing
• Separator
• Cylindrical, prismatic,

pouch

Cell Designer

• Performance estimation
• Model selection
• Series/Parallel cells
• Cooling

End User, Module and/or Pack Developer, End

TBM file, prg, out TBM file

Battery Design Studio Star CCM+

CD-adapco is the only provider of an integrated solution for cell, module, battery, and system design.

43

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)

44

Air Temperature Animation

Air Flow Maximum Temperatures Courtesy of Bob Reynolds, CD-adapco

45

EV Battery (15S-3P) Example – Air Cooling

Cooling Media Temperature distribution Battery SOC Distribution Battery Temperature Distribution Coupled Flow/thermal & electrochemical solution

Courtesy of

• G. Damblanc,

CD-adapco

46

47

48

Conclusion

• CD-adapco is clear leader in battery

simulation.

• ANSYS is working in this area, but it is not

clear what product they are developing.

• COMSOL is preferred product for model

development in academia, and has some traction in industry (example Ford).

• There are a number of other companies
• ffering products.

49

Future Development: Life Prediction

LIFE PREDICTION

A Grand Challenge for Battery Modeling

• How many years of service a battery will provide

is a critical concern for large-scale applications of batteries such as electric vehicles and grid energy storage.

• Problem is considered as comprised of calendar

life and cycle life components.

• The key stress factors are known to be

– temperature, – state of charge, – depth of discharge, – discharge/charge rates.

51

Calendar Fade due to Film Growth

SEI (P)

Graphite

L

Li+

Film at Solid Electrolyte Interface (SEI) grows due to reduction of solvent

P e Li S   



2 2

Solvent (S)

S

e- e- e- e- e- e- e- e- e- e- e- e- e- e- Ploehn et al. “Solvent diffusion model for aging of Lithium-Ion battery cells”, J.

• Electrochem. Soc., 151 (3), A456 – A462 (2004).

   

t RT E D t L L t L R R

a

• S
• SEI

SEI

         exp 2 , 

Model predicts capacity loss and impedance growth as function of time and temperature

52

Cycle Fade using Analogy to Wöhler Fatigue

• M. W. Verbrugge and Y.-T. Cheng, J. Electrochem. Soc., 156 (11) A927-A937 (2009).

Approach predicts capacity loss and impedance growth as function of cycle #, charge/discharge rate

53

Commodity Pricing

• 18650 size lithium-ion cell ~$2 or $0.25/Wh
• Lead acid car battery (12V, ~50 Ah) ~$60-90 or

~$0.1-0.15/Wh Note: Unlike lead-acid, lithium-ion requires electronics for safety.

54

In practice lithium-ion is typically >3X cost of lead acid.

Rechargeable Battery Producers and Customers

Lithium-ion Producers

Samsung, Panasonic/Sanyo, LG, GS Yuasa, Hitachi, NEC, Toshiba, SK, Sony, Lishen, BYD, A123, JCI, Saft, others

Pb Acid Producers

JCI, Exide, Panasonic, Trojan, many others

Customers

• Consumer electronics

– Apple, Panasonic, Sony, LG, Samsung, Lenovo, Dell, HP, HTC, RIM, Motorola, etc.

• Automotive

– Toyota, Honda, GM, Ford, Nissan, BMW, Daimler, VW, Audi, etc. – Sears, Walmart, etc.

• Industrial

– UPS – Sony, Panasonic, etc. – Tools – Black & Decker, Bosch, Ryobi, etc. – E-bikes-Honda, Yamaha, Accell, etc.

• Military – all branches

55

Major lithium-ion producers tend to be large vertically integrated companies.