锂电老化机理和诊断分析(全英文)

:DavidK.Jamison,INLBorYannLiaw,HNEIChristopherJ.Michelbacher,INLMatthieuDubarry,HNEISergiyV.Sazhin,INLMikaelCugnet,HNEIJune10,2010ProjectIDES0962010DOEVehicleTechnologiesProgramAnnualMeritReviewThispresentationdoesnotcontainanyproprietary,confidential,orotherwiserestrictedinformation.TimelineProjectStart:April2008ProjectEnd:OngoingPercentComplete:ExtentofprojectcompletiondependsonmeetingkeydecisionpointsandmilestonesbuiltintoscheduleBarriersCell/batteryLifeandrelatedpathdependenceBudgetFundingReceived:FY08:$80KFY09:$220KFY10:$460KPartnersHawaiiNaturalEnergyInstituteUniversityofCaliforniaatPomonaArgonneNationalLabOverviewObjectives/RelevanceLong-termusageoflithium-ionbatteriesinvehicleapplicationsrepresentsasignificantwarrantycommitment.Yet,thereisinsufficientknowledgeregardingagingprocessesinsuchbatteries,particularlyincasesofstrongpathdependenceofperformancedegradation.Ourobjectivesinclude*:♦DevelopaplatformofDiagnosticTesting(DT)gearedtowardspecificissuesinvehicularapplications(e.g.,HEV,PHEV).♦EmployDTtoexaminemechanisticcontributionstocellaging.♦DevelopadvancedmodelingtoolsthatwillcomplementDT.♦Develop/optimizeanoperationalprotocoltominimizetheagingprocess(chemistry-specific,butwithgeneralizedapproach).Thiscollectiveeffortwillallowustoanswerfundamentalquestionsonagingprocesses,pathdependencethereof,andfindwaystomitigateperformancelimitationsoverlife.*PerformedunderUSDOEAppliedBatteryResearchforTransportation(ABRT)ProgramApproach‰ThisworkaimstobridgethegapbetweenideallaboratorytestconditionsandPHEVfieldconditionsbyisolatingthepredominantagingfactorsofLi-ioncellsinPHEVservice,whichwouldinclude,forexample,thenatureandfrequencyofdutycycles,aswellasthefrequencyandseverityofthermalcycles.‰ThroughDT,thesefactorsarethenstudiedincontrolledandrepeatablelaboratoryconditionstofacilitatemechanisticevaluationofagingprocessesandpathdependencethereof.‰CollaborationwiththeHawaiiNaturalEnergyInstitute(HNEI)providesasynergisticbasisduetothecomplementaryhistoriesofINLandHNEIinbatterytesting,research,andmodeling.‰Modelingtoolsdevelopedandemployedarethosethatpromotediagnosticanalysisovermultipledomains,lookingatagingmechanismsandkeyperformanceissues.InsomecasesaLi-ioncellisviewedasabatchreactorwithagingprocessesmodeledbysigmoidalmathematics.ModelingAgingCellsasBatchReactors:Chemicalkineticsandthermodynamicconsiderationsofdegradationprocessesdeterminetheeffectiveratethatcellsage,affectinglossesincapacity,power,generalperformance,andancillaryquantitiesoverservicelifeofelectrochemicalcells.Sigmoidalexpressionsarewellsuitedtodescribetheseprocesseswithinabatchreactorscenario,e.g.,forperformancelossatagingconditioni(Ψi)wehave:Thesemathematicalexpressionsareself-consistent,properlybounded,adaptive,relevanttocellenvironments,andeasilylendthemselvestoacomprehensivedegradationrateanalysisofperformancedata.()11221exp⎡⎤⎢⎥Ψ=Σ−⎢⎥+⎣⎦jijbjjiMatCurrent(I),heat(Q)QIIPathDependenceofCellAgingƒTheextentandrateofcellagingovertimedependsonspecificoperationalconditions(stressfactors)encounteredoverthetimeline.Pathdependenceassertsthatthesequenceofagingconditions(aswellasthenatureofconditions)hasadirectinfluenceontherateofagingandnetagingalongthetimeline.Think“batchreactor”.ƒAchangeinagingconditionscanaccelerateordeceleratedegradationmechanisms,andcaninitiatenewones.Reactionkineticsandthermodynamicsarekeytounderstandingtheagingprocessalongthepath.ƒCellagingshouldbesimultaneouslyjudgedfromlossofcapacity,riseinimpedance,lossofpower,selfdischarge,etc.,whereeachrequireastandardbasis.Shownisanidealizedprojectionofapathdependenceinvolvingfourdistinctagingconditions.Anactualcellmightencountermanytimesmoreuniqueagingconditionswhileinservice.Pathdependenceassertsthatarandomizedrearrangementofthefourconditionswilllikelynotreproducethereferenceagingof(∗)bytheendofthefourthperiod.INLagingmodelsareeasilyadaptabletoPathDependencescenariosLi-ionChemistryUsedforStudies:Sanyo‘Y’Thesecellsarehighquality,showinggoodstabilityandlowcell-to-cellvariability.ExampleofDiagnosticTesting:AgingPathDependence(twoongoingstudies)PathDependenceStudies(twoexamples)Study1:Constant-powerpulsesofvariousmagnitudes,usingatime-averagecumulativedischargeenergythatisequalforallscenarios.Isthereanagingpathdependenceduetoseverityandrandomnessofpowerpulses?vsvsvsvsConstantcurrentchargeScenario1(Baseline)Scenario2Scenario3Scenario4Scenario5PathDependenceStudiesƒThisisavaluablestudyintransitioningbetweenidealizedlabdataandactualPHEVfielddata.ƒTemperatureandcyclingparameterscanbetailoredforspecificregionaltargets.ƒAddedvalueisgottenthroughINL/HNEIsynergy.Themainparametersare(1)themagnitudeandfrequencyofthethermalcycling,lookingatisothermal,mild,andseverescenarios,and(2)frequencyofdutycycle.Study2:Combinationofcellcycling(PHEVprotocol,CD+CS)andthermalcycling.Isthereanagingpathdependenceduetocell