[2005 JPS] Applications of high power density lithium ion batteries.pdf

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JournalofPowerSources146(2005)107110ApplicationsofhighpowerdensitylithiumionbatteriesT.Horibaa,∗,T.Maeshimaa,T.Matsumuraa,M.Kosekia,J.Araib,Y.MuranakabaShin-KobeElectricMachineryCo.,Ltd.,Okabe-machiOhsato-gun,Saitama369-0297,JapanbHitachiResearchLaboratory,Hitachi,Ltd.,Ohmika-choHitachi,Ibaraki319-1292,JapanAvailableonline20June2005AbstractIn2003,wedevelopedanewtypeoflithiumionbatteryforthelightvehicleapplication,inwhich14cellsof7Ahwereintegratedintoabatterypack.Ithasthehighratedischargecapabilityupto5Crate(35A),aenergydensityof74Whkg−1,andthelowtemperaturedischargecapacityat−5◦Cmorethan90%ofthatat25◦C.Thelifecycletestof100%depthofdischarge(DOD)at35◦Cshowedthecapacityfadingaround10%after500cycles,whichconfirmedmuchlongerpracticallifethan2years.Recently,wehavedevelopedanewhighpowercell.Ithasthecapacityof5.5Ah,andhastheoutputpowerdensityof3000Wkg−1at50%stateofcharge(SOC)andat25◦Cfor5sdischargebasis,andtheinputpowerdensityof2200Wkg−1atthesameconditions.Thenewcellsshowedmuchlessincreaseindirectcurrentresistance(DCR)inboththecyclelifetestandthestoragelifetestthanthecellsdevelopedbefore,whichconsequentlyimpliedmuchlongercalendarlifethanourpreviousonesdevelopedin2000.©2005ElsevierB.V.Allrightsreserved.Keywords:Directcurrentresistance;Lithiumionbattery;Calendarlife1.Introductioniesinmodulebasis.Thehighenergydensityperformanceoflithiumionbatteriesisexplicitlyillustratedinthefigure.WehavebeendevelopinglithiumionbatteriessincetheTheplotsofHEVandpure-EVarethosethatwedevel-beginningof1990s,asamemberofnationalprojectofJapan,opedin2000asdescribedabove.ThesetwoplotsprovethatnamedTheDevelopmentofDispersed-TypeBatteryEnergythelithiumionbatteriesareflexibleenoughtobedesignedStorageTechnology.Wehavebeenconcentratingonthefromhighpowerspecificationtohighenergyspecification.manganese-basedpositiveelectrodematerialsintheprojectTheplotoflightvehicleinFig.1correspondstothatwe[1].Byutilizingtheresultsdevelopedintheproject,wehavedevelopedrecentlyanditalsoprovestheflexibilitymentionedreleasedlargecapacitycellsof90Ahforelectricvehicle(EV)above.Thefeaturesandperformanceforitbesideswiththatapplication[2]andhighpowercellsof3.6Ahforhybridforthenewhighpowerdensitycellwillbediscussedinthiselectricvehicle(HEV)application[3].Theywereappliedtopaper.commercialvehiclesin2000[4].Amongthem,weexpectedtheapplicationofhighpowerdensitylithiumionbatteriestobethemostpromisingone,forittakestheadvantageofthe2.Experimentalmostoutstandingfeatureoflithiumionbatteriesquitewell.Recently,wehavedevelopedtwotypesofimprovedlithiumThecellchemistryofthelithiumbatteryconsistedofbatteries.Oneisthehighenergydensityandmediumratemanganese-basedmaterialpositiveelectrodeandhardcar-batteryforlightvehicleapplication,andtheotheristhehighbonnegativeelectrode.ThepositiveelectrodewasformedpowerdensitycellfortheHEVapplication.onanaluminumfoilbycoatingwithanactivematerialmix-Fig.1isaRagoneplotshowingspecificenergydensityandturecontainingtheactivematerial,theconductivematerialspecificpowerdensityforvariouskindsofsecondarybatter-andthebinder.Thenegativeelectrodewasformedonacop-perfoilbycoatingwithanactivematerialmixturecontaining∗Correspondingauthor.Tel.:+81485461107;fax:+81485461138.theactivematerialandthebinder.TheelectrolyticsolutionE-mailaddress:t.horiba@shinkobe-denki.co.jp(T.Horiba).consistedoflithiumhexafluoro-phosphateandamixtureof0378-7753/$seefrontmatter©2005ElsevierB.V.Allrightsreserved.doi:10.1016/j.jpowsour.2005.03.205 108T.Horibaetal./JournalofPowerSources146(2005)107–110PulsecycletestisasimplifiedtestpatterntosimulatetherealloadpatternofHEV,anditwasadoptedtopredicttheHEVbatterylifeaffectedbythestressoftheiterativechargedischargecyclesinavehicleoperation.Weusedarathershallowdutycyclemodeof1%SOC/cycle.WecalculatedtheDCRastheslopeofaIVcurveobtainedbyfollowingtheproceduredescribedabovein(1)(4).DCRisthoughttobeinthereciprocalrelationshipwiththeoutputortheinputpower;thereforeitwillbeagoodscaletoestimatethepowercapabilityofthebattery.3.LightvehiclebatteryFig.1.Comparisonofvarioussecondarybatteries.Theperformancerequestedbythelightvehicleapplicationisconsiderablydifferentfromthatbythefour-wheelvehicles;thebatteryisalmostnakedtotheenvironment,therefore,theorganiccarbonatesolvents.Theseparatorwasanordinarybatterytemperaturebecomesnearlyequaltotheenvironmen-polyolefinmicroporoussheet.Thecellshapewascylindri-taltemperatureandtheshockimpacttothebatteryisalmostcalandthepositiveelectrode,theseparatorandthenegativethesameasthattothevehiclewheels;extremelycoldtem-electrodewerewoundintoawoundelectrode.Thewoundperatures,suchasbelow−10◦C,arenotsupposed;theloadelectrodewasputintothecellcasingandcrimpedwiththepatternisnotcontinuousbutratherpulsativethoughitisagasketandthecapaftertheinjectionoftheelectrolyticsolu-kindofpureelectricvehicle.tion.ThecellandmodulebatteryweredevelopedtakingtheseTheratedcapacityforthelightvehiclecellwasmeasureddifferencesintoconsiderations.Table1showsthespecifica-at25◦Cbyadischargecurrentof7Adownto2.7Vaftertionsforthelightvehicleapplicationcell.ThedimensionstheCCCVchargingat7.5Aconstantcurrentupto4.2Vforitare40mmindiameterand125mminlength,andtheofconstantvoltagefor3hintotaltime.Theratedcapacitymassforitis350g.Therefore,thespecificenergydensityisforthenewHEVcellwasmeasuredat25◦Cbyadischarge74Whkg−1andvolumetricenergydensityis165Whdm−3.currentof2Adownto2.7VaftertheCCCVchargingatRatedcapacityis7Ahandhighratedischargeupto5C6Aconstantcurrentupto4.1Vofconstantvoltagefor2.5hrate,namely35A/cell,iscapable.Evenat0◦Corless,lightintotaltime.vehicleisrequestedtohavealmostthesamemileageasWefiguredthepowerprofile,orinput/outputpowerstate25◦C.Weimprovedthelowtemperaturedischargeperfor-ofcharge(SOC)diagram,toevaluatethepowercapabilityofmanceat−5◦Cbyadjustingcelldesign.Theresultsarethehighpowerdensitycell.Themethodisakindofextrap-showninFig.2.Thelowtemperatureperformancedownolationandtheprocedureisasfollows:to−5◦Cwasimprovedenoughtokeepmorethan90%ofthedischargecapacityat25◦C.Fig.3showstheresultsof(1)ApplyaconstantcurrentofacertainvalueI1tothetestchargedischargecyclelifetestconductedat3.75A(1/2CcellofacertainSOC.rate)CCchargeand4.2VCVchargeupto3hintotal,and(2)Measurethecellvoltageafteracertaindurationoftime,30Adischargedownto100%depthofdischarge(DOD).Theforexample,5s.dischargecapacityafter500cyclesat35◦Cremainedaround(3)Repeat(1)and(2)attheincreasedcurrentvaluesofI2,90%oftheinitialcapacity,whichconfirmedmuchlongerlifeI3,orfurther.than2yearsinthepracticalusage.(4)PlotthecellvoltagesagainstI1,I2,I3,orfurthertodrawanIVcurve.(5)ExtrapolatetheIVcurve,obtainedat(4),downtotheTable1Specificationsoflightvehiclecellcutoffvoltageofdischarge,forexample,2.5V.ThentheImax(1)isdetermined.ItemSpecification(6)CalculatePout(1)astheproductof2.5VandImax(1).Cellchemistry(±)Mn-based/hardC(7)MovetoanotherSOCandrepeatfrom(1)to(6),thenNominalvoltage3.7VRatedcapacity7AhPout(2)isobtained.(8)PlotallthePout(n)sagainstSOC,thenthepowerprofileDimensionsfortheoutputisdrawn.Length125mmDiameter40mm(9)Fortheinputpower,similarproceduresfrom(1)to(8)areapplicable;however,4.2Vshouldbeusedasnotdis-Mass350gContinuousmax.dischargecurrent5CA(35A)chargebutchargecutoffvoltagein(5)and(6). T.Horibaetal./JournalofPowerSources146(2005)107–110109Table2PrerequisiteforlifecycleassessmentVehicleElectricscooter(Libattery)ICEscooter(50mlengine)Onechargemileage:32kmAveragefueleconomy:63kmdm−3Cyclelife:500cyclesTotalmileage:16,000kmTotalmileage:16,000kmGasolineconsumption:16,000km/(63kmdm−3)=245dm3Chargeenergy:26V×14Ah×500timesChargeefficiency:85%Drivespeed:30kmh−1.Fig.2.Improvementof30Adischargeperformance.16,000km,thesameastheelectricscooter,andtheaveragefueleconomyis63kmdm−3-gasoline.TheresultsfortheLCAareshowninTable3.Conse-quently,two-thirdsofcarbondioxide,and90%ofSOxandNOxcanbereducedbytheintroductionoftheelectricscooter.4.HEVbatteryTable4showsthecomparisonoftheHEVcellspecifica-tionsbetweenthatdevelopedin2000calledGen1andthatdevelopedrecentlycalledGen2.ThesetwocellshavetheFig.3.Lifecycletestoflightvehiclecell.samedimensionsandthesamemass;howeverthecapacityandpowerdensityofGen2are1.5timesofthoseofGen1.Sincethecapacity,thepowercapability,thelowtemper-Thebigimprovementshowninthetableissupportedbytheatureperformanceat−5◦Candthecyclelifeperformancesomeinnovationofthepositiveelectrodematerialandthemetthetargetforthelightvehicleapplication,14-cellmoduleelectrolyticsolution.Fig.4showsthepowerprofileat25◦Cbatteryfortheapplicationwasdesigned,consistingoftwo-basedon5svoltages.At50%SOC,Gen2cellhastheoutputparallelcellsconnectedinseven-series.Theratingforitwas14Ah26V,thedimensionswere95mmindepth,370mminlengthand147mminheight,andthemasswas6kg.ThelightvehicleisakindofelectricscootersandalreadylaunchedintothemarketbyYamahaMotorCo.[5].Althoughitisasmallvehicle,itissurelyclassifiedasapureelectricvehi-cledrivenonlybyelectricpowerwithzeroemission.Weevaluatedthemeritfortheelectricscooteragainstacon-ventionalICEscooterwiththelifecycleassessment(LCA)method.Table2showstheprerequisitefortheLCA.Onechargemileagefortheelectricvehicleis32kmandtotalmileagebytheendofthelifeis16,000km.Energyefficiencyofchargingis85%.TheICEcapacityisassumedtobe50ml,totalmileagebytheendofthelifeisalsosupposedtobeFig.4.PowerdensityprofileofGen1andGen2cell.Table3ResultoflifecycleassessmentforlightvehiclebatteryVehicleEnergyconsumptionGasemission(g/veh.)CO2SOxNOxElectricscooter(Libattery)Libattery:manuf.todisp.115,172176100Totalmileage(16,000km)82,1764362Total197,348219162ICEscooter(50mlengine)Drivenbygasoline(16,000km)599,18617782083Reductionrateofemissionbyelectricscooter(%)678892 110T.Horibaetal./JournalofPowerSources146(2005)107–110Table4HighpowerLiioncell:Gen1andGen2ItemGen1Gen2Dimensions(mm)Ø40×108Ø40×108Mass(g)300300Nominalvoltage(V)3.63.6Capacity(Ah)3.65.5Outputpowerdensity(Wkg−1)a20003000Inputpowerdensity(Wkg−1)a15002200aAt50%SOCand25◦C.Fig.7.DCRchangeinstoragelifetest.isshown.TheDCRforGen1cellincreasedtothedoublinglevelafter300,000cycles,whilethatfortheGen2showedlessthan10%ofincrementafter250,000cycles.TheseresultsmeanthatthepowerfadinginthepulsecycletestfortheGen2cellismuchreducedcomparingtothatfortheGen1cell.Fig.7showstheDCRchangesinthestoragelifetestofa50%SOCcellat50◦C.TheDCRincrementfortheGen2cellismuchlessthanthatfortheGen1cell,andtheDCRafter150daysstorageis3.4m,suggestingthetendencyofsaturation.TheseexcellentlifetestdataareexpectedtoFig.5.Lowtemperaturepowerprofileat−30◦C.supportalongercalendarlifeinthepracticaluseoftheGen2lithiumionbatteryfortheHEVapplication.Evenforthepowerdensityof3000Wkg−1,andtheinputpowerdensityGen1cell,thelifelongerthan5yearsor100,000kmlifeof2200Wkg−1.ThepowerdensitiesoftheGen1cellwereisexpectedinpracticalapplication[3,6],sothecalendarlifeimprovedthroughoutthewholeSOCspan.morethan10years,andmaybe15years,isexpectedforFig.5showstheimprovementinlowtemperaturepowertheGen2cellbasedonthemuchsuppressedDCRincreasecapabilityat−30◦C.TheGen2cellcandelivertheoutputshowninFigs.6and7.andinputpowerover50W/cellbetween25%SOCand60%SOCevenat−30◦C.Thelargeimprovementwasdependentonthematerialinnovationinthepositiveelectrodeactive5.Conclusionmaterialandtheelectrolyticsolution.Thepowerprofilewascalculatedbasedonthesameconditionsas25◦C,namelyWehavebeendevelopingLiionbatteriesforindustrialthe5spulsevoltageandthecutoffvoltageof2.5V.Iftheapplication,suchastheautomotive.Basedonthelast10conditionswereloweredtotheshorterpulseandtheloweryearsR&Dresults,wehavedevelopedtheGen2cellwithcutoffvoltage,thepowerprofilewouldbeabletoshowmuchhighpowerandlongerlife.Weexpectthatfurtherapplicationbettervalues.oftheLiionbatterywilldevelopinvolumeandvarietyintheInFig.6,theDCRchangesinshallowdutypulsecyclenearfuture.test,1.5%fortheGen1celland1%forGen2cell,at50◦CReferences[1]T.Horiba,M.Kosei,T.Ishizu,T.Kojima,K.Takahashi,Y.Muranaka,S.Nishimura,Proceedingsofthe43thBatteryConference,Fukuoka,Japan,3A05,October,2002,pp.204205.[2]T.Horiba,K.Hironaka,M.Matsumura,etal.,J.PowerSources97-98(2001)719.[3]T.Horiba,K.Hironaka,T.Matsumura,T.Kai,M.Koseki,Y.Muranaka,J.PowerSources119121(2003)893.[4]T.Horiba,K.Hironaka,T.Matsumura,T.Kai,M.Koseki,Y.Muranaka,Proceedingsofthe17thInternationalElectricVehicleSym-posium,Montreal,Canada,4B-3,October1518,2000.[5]T.Ono,Proceedingsofthe20thInternationalElectricVehicleSym-posium,LongBeach,CA,November1519,2003.[6]M.Origuchi,N.Hirata,etal.,Proceedingsofthe17thInternationalElectricVehicleSymposium,Montreal,Canada,3B-3,October1518,Fig.6.DCRchangeinlightdutypulsecycletest.2000.