Designing Safe Lithium-Ion Battery Packs Using The

NRELisanationallaboratoryoftheU.S.DepartmentofEnergy,OfficeofEnergyEfficiencyandRenewableEnergy,operatedbytheAllianceforSustainableEnergy,LLC.AhmadA.Pesaran,Gi-HeonKim,KandlerSmith([e-mail])NationalRenewableEnergyLaboratoryEricC.DarcyNASAJohnsonSpaceCenterNREL/PR-540-45388DesigningSafeLithium-IonBatteryPacksUsingThermalAbuseModelsNationalRenewableEnergyLaboratoryInnovationforOurEnergyFuture2Background–Forpoweringspacesuits,NASAisconsideringusingabatterypackconsistingofarrays(16P-5S)of18650Li-ioncells.–Thesecellsareequippedwithapositivetemperaturecoefficient(PTC)deviceproveneffectiveforcontrolofovercurrenthazardsattheLi-ioncellandsmallbatterylevel.–However,PTCdevicesarenotaseffectiveinhigh-voltagebatterydesigns.–Afireina2004MemphisFedExfacilitysuspectedtobeduetoaPTCdevicefailureinalarge-capacity(66p-2s)batteryshortedwhileat50%SOC.NationalRenewableEnergyLaboratoryInnovationforOurEnergyFuture3PTCDevice:Background•Commerciallithium-ion18650cellstypicallyhaveacurrent-limitingPTC(positivetemperaturecoefficient)deviceinstalledinthecellcaptolimitexternalcurrentsintheeventofanexternalshorttothecell.•ThePTCdeviceconsistsofamatrixofacrystallinepolyethylenecontainingdispersedconductiveparticles,usuallycarbonblack.*TheresistanceofthePTCdeviceincreaseswithtemperature.•ThePTCresistanceincreasessharplywithtemperature.Whenashortisappliedtoacell,theelevatedcurrentscausethePTCtoself-heatandmovetoahigh-resistancestateinwhichmostofthecellvoltageisacrossthePTCbutthecurrentissignificantlyreduced.•Aslongastheshortismaintained,thePTCdeviceproducesenoughheattokeepitselfinthistrippedstate(lowercurrentisoffsetbygreatervoltagedropacrossPTC).SingleCellShort:*Doljack,F.,IEEETransactionsonComponents,Hybrids,andManufacturingTechnology,4,732,1981NationalRenewableEnergyLaboratoryInnovationforOurEnergyFuture4CellDesignFeaturesforAbuseToleranceCrimpedCanGasketSealPTCring+TopCoverCIDButtonCIDringpolymer+TagmountingdiskScoredDiskVentSonyHCCellMoliICR-18650JNationalRenewableEnergyLaboratoryInnovationforOurEnergyFuture5MotivationforthisWork•CanNASA’sspacesuitbatterydesign(16p-5s)arraydependoncellPTCdevicestotolerateanexternal16pshort?•Istherearangeofsmartshortsthatcanbehazardous?GasketSealPTCring+TopCoverCIDButtonCIDringpolymer+TagmountingdiskScoredDiskVentGasketSealPTCring+TopCoverCIDButtonCIDringpolymer+TagmountingdiskScoredDiskVentNationalRenewableEnergyLaboratoryInnovationforOurEnergyFuture6Objectives•CreateanengineeringmodeltoguidethedesignandtoverifythesafetymarginofabatteryusinghighspecificenergyCOTScells•UsethemodeltoprovideinputfordesigningaNASA16p-5s18650spacesuitbattery–CellmodelmustincludetheelectricalandthermalbehaviorofthecellPTCdevice–Usecellmodelasbuildingblocktomodelmulti-cellbatterybehaviorundershort-circuitconditions–AssesstherangeofsmartshortconditionsthatpushcellsclosetotheonsetofthermalrunawaytemperatureNationalRenewableEnergyLaboratoryInnovationforOurEnergyFuture7UtilizingNREL’sMulti-physicsBatteryModeling•ElectricalPerformanceModeling–Cells&multi-stringmodules•ThermalModeling–Cells&modules•Thermal/ElectrochemicalModeling–Cells•Thermal/ChemicalAbuseModeling*–Cellsandmodules*G.-H.Kim,A.Pesaran,“AnalysisofheatdissipationinLi-ioncellsandmodulesformodelingofthermalrunaway,”3rdInternationalSymposiumonLargeLithiumIonBatteryTechnologyandApplication,LongBeach,CA,May2007.Available:(Cu)CurrentCollector(Al)pNegativeElectrodeSeparatorPositiveElectrode050100150200250300468101214050100150200250300468101214∆i[%]050100150200250300468101214VT-TavgNationalRenewableEnergyLaboratoryInnovationforOurEnergyFuture8Overview•Modeling–Approach–PTCdevice–Cell•Electrical•Thermal(5-node)–Module•Electrical(multi-nodenetwork)•Thermal(multi-nodenetwork)•ValidationwithexperimentsfromSRI–16Pmodulewith10mΩexternalshort•Parametricstudy–Resistanceofexternalshort–Heatrejectionratetoambient•ConclusionsPhoto:SymmetryResourcesInc.(SRI)NationalRenewableEnergyLaboratoryInnovationforOurEnergyFuture9ModelingApproachPreviousWork:•DesignmoduletopreventthermalrunawaypropagationPresentWork:•Verifymoduledesigntoleranttoexternalelectricalshort010203040506070809010001002003004005006007001234567891011121314151617181920ThermalNetworkModelChemicalReactionModel+ThermalNetworkModelElectricalModel+Photo:SymmetryResourcesInc.17500069055Temperature[oC]HeatGeneration[oC/min]NationalRenewableEnergyLaboratoryInnovationforOurEnergyFuture10PTCResistanceversusTemperature;MoliICR-18650JCellheaderremovedfromcellwithoutdisturbingclosureconfigurationResistancemeasurementstakenfromrupturedisksurfacetopositivebutton1.0E-021.0E-011.0E+001.0E+011.0E+021.0E+031.0E+041.0E+051.0E+060102030405060708090100110120130140150160170180Temperature(deg.C)Resistance(ohms)PTC71A06virginPTC71A07virginPTC71A08virginPTC71A09trippedPhaseTransitionNationalRenewableEnergyLaboratoryInnovationforOurEnergyFuture11BehaviorPrincipleso