EVS28KINTEX, Korea, May 3-6, 2015

Battery Development Process withSafety

Andrew KwonGeneral Motors Korea

Jungkee.kwon@gm.com

Why Safety?

Aftermarket Battery Fire

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EV in public marketis not the first time

Safety process hasnot been considered

Safety First Culture

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Component DesignVehicle DesignLife & Work

Preliminary HazardAnalysis Fault Tree Ana

lysis

Subsystem Technical Specificati

onDFMEA

Analysis, Development & Validation Pla

n & Report

Safety Concept

Safety Peer Reviews

GM Safety Development Process

Safety Design Guideline on Battery Pack

Separation is the Key

Keep Part A Apart from Part B By Because…

1 PositiveElectrode

NegativeElectrode

Separator Short Circuit

2 Positive Current Collector

Negative Current Collector

Barrier,Gasket,Distance

Short Circuit

3 Battery Voltages Chassis Potential Insulation,Creepage, Clearance

Loss of Isolation

4 Battery Voltages Coolant / H20 Insulation,Creepage, Clearance

Loss of Isolation, Corrosion

5 Vented Material Battery Voltages Barriers, Distance

Short Circuits

6 Vented Material Chassis Potential Barriers, Distance

Loss of IsolationCorrosion

VOLTec battery system

Battery system located outside of crash zone. Tray is an integralpart of the body structure and contributes to both static anddynamic performance.

Safety structural integration with vehicle

Verification - Vehicle level CAE study list

Side Pole CrashRear CrashFrontal crashPedProRCARNVHElectrical IntegrityBattery Protectionetc

I. Burn TestII. Water Submersion TestIII. Coolant Submersion TestIV. Vehicle Water Submersion TestV. All Crash TestVI. Durability Test

Battery system development: pack to vehicle

Validation : pack to vehicle

Vehicle development with battery focus

Final calibration of the battery control software.Mechanical verification of battery installed in vehicle.

Verification - Pack level CAE study list

Random VibrationTwist DitchFoot loadSealingModalLifting pointMinor collisionDrop testFlow analysisFuse durabilityetc

Validation - Pack Level Safety Test(1)

Pack Crush Tests

SAE J2929 Pack Drop Test

KMVSS 4.9M Pack Drop Test

Pack Hard Short Test

Pack Matched Impedance Test at -10C,25C

Pack High Impedance Short Test (200% of Fuse Current

Rating)

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Pack Level Safety Test(2)

Fire Test

Thermal Management Test (SAE J2929 & ECE R100)

Pack Overcharge with Controls (KMVSS & ECE R100)

Pack Over discharge with Controls (KMVSS & ECE R100)

KMVSS Pack Heat Exposure Test

Pack Submersion/ Immersion Test

Coolant Exposure Test

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Verification - Section level CAE study list

Cell ExpansionMino collisionDrop testThermal flowCrush testMechanical shockVibration

Section level safety test

Sense Lead Hard Short Circuit Tests

Resistive short Circuit Tests

Half Pack Hard Short Test at 25C

Thermal Propagation Test

Sense Lead Hard Short Module Connector

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Cell Requirements: Safety, Life, Power, Energy

I. The electric vehicle, with extended range, requires highenergy density and high power density. Due to large size, thebattery has to have high abuse tolerance. Long life is requiredto meet emission regulations and establish customerconfidence.

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Life cyclingCell penetrationCell crushCell thermal stressCell overcharge

Lithium Ion technology selection

Lithium Manganese based cathode cell chemistry provides bestbalance of energy and power density, battery life and abusebehavior. Thin pouch cells have a large surface for heat exchange.

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Cathode

Criteria NCA Mn-based LFP

Energy density Good Good Medium

Power density Good Excellent Good

Battery life Good Medium Good

Abuse tolerance Poor Excellent Excellent

Anode material Cathode material

Graphite Li-NiMnHard carbon Li-FePMCMB Li-Mn-basedLi4Ti5O12 Li-Mn-spinel

Li-NCALi-NMCLi-CoO2

Cell Level Abuse Tests

Batteries Store EnergyWe have to understand what happens when it is released without controlby characterizing the potential responses with abuse tests.

I. OverchargeII. Internal Short CircuitIII. External Short CircuitIV. Excessive CrushV. Excessive High TemperatureVI. Submersion

Sandia researcher Peter Roth prepares to blow upa battery to see how robust it is. The work is partof the DOE-funded FredomCAR program. (Photoby Randy Montoya)

Conclusion

I. Safe BEV development is not easy like combustion enginevehicle.

II. Development process of BEV should be the same ascombustion engine vehicle even more consider of safety

III. Takes tremendous effort to design & validate the batteryIV. Need to have pack/section/cell level safety protection in

order to integrate into vehicle.

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Thank you

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