Lithium-Batteries-and-Cathode-Materials

LithiumBatteriesandCathodeMaterialsM.StanleyWhittingham*DepartmentofChemistryandMaterialsScience,StateUniversityofNewYork,Binghamton,NewYork13902-6000ReceivedJune16,2004Contents1.Introduction42712.OriginsoftheLithiumBattery42732.1.EarlyConcepts42732.2.MoltenSaltSystemsatArgonneNationalLaboratoryandGeneralMotors42732.3.ConceptofMixedConductors42732.4.EarlyIntercalationConcept42743.1972-1980:BirthoftheRechargeableLithiumBattery42743.1.IntercalationintheLayeredDichalcogenides42743.2.TrichalcogenidesandRelatedMaterials42773.3.MovementintoOxides42773.3.1.LayeredOxides42773.3.2.High-ValentOxidesofVanadiumandMolybdenum42773.3.3.Mixed-ValentOxidesofVanadiumsV6O13andLiV3O842783.3.4.Double-SheetStructures:Xerogels,ä-VanadiumOxides,andNanotubes42784.1980-1990:EraofLayeredOxidesandFirstLargeCommercialization42794.1.EarlyStudiesofLayeredOxides42794.2.LithiumCobaltOxide,LiCoO242804.3.LithiumNickelOxide,LiNiO242815.1990-Present:Second-GenerationLithiumBatteries42825.1.Spinels42825.2.OtherLayeredOxides42835.2.1.MixedNickel-CobaltDioxide,LiNi1-yCoyO242835.2.2.LithiumManganeseDioxide,LiMnO242835.2.3.MixedManganese-CobaltDioxide,LiMn1-yCoyO242845.2.4.MixedNickel-ManganeseDioxide,LiNi1-yMnyO2sMultielectronRedoxSystems42855.2.5.MixedNickel-Manganese-CobaltDioxide,LiNi1-y-zMnyCozO242875.2.6.Lithium-RichMixed-MetalDioxides,Li1+xM1-xO242925.3.IronCompoundsIncludingOxidesandPhosphates42935.3.1.OlivinePhase42935.3.2.OtherIronPhosphatePhases42955.3.3.VanadiumPhosphatePhases42966.ConclusionsandWhatDoestheFutureHold42977.AbbreviationsandSpecializedTerms42978.Acknowledgments42979.References42971.IntroductionInthepreviouspaperRalphBroddandMartinWinterdescribedthedifferentkindsofbatteriesandfuelcells.InthispaperIwilldescribelithiumbatteriesinmoredetail,buildinganoverallfounda-tionforthepapersthatfollowwhichdescribespecificcomponentsinsomedepthandusuallywithanemphasisonthematerialsbehavior.Thelithiumbatteryindustryisundergoingrapidexpansion,nowrepresentingthelargestsegmentoftheportablebatteryindustryanddominatingthecomputer,cellphone,andcamerapowersourceindustry.However,thepresentsecondarybatteriesuseexpensivecom-ponents,whicharenotinsufficientsupplytoallowtheindustrytogrowatthesamerateinthenextdecade.Moreover,thesafetyofthesystemisques-tionableforthelarge-scalebatteriesneededforhybridelectricvehicles(HEV).Anotherbatteryneedisforahigh-powersystemthatcanbeusedforpowertools,whereonlytheenvironmentallyhazardousNi/Cdbatterypresentlymeetstherequirements.Abatteryisatransducerthatconvertschemicalenergyintoelectricalenergyandviceversa.Itcontainsananode,acathode,andanelectrolyte.Theanode,inthecaseofalithiumbattery,isthesourceoflithiumions.Thecathodeisthesinkforthelithiumionsandischosentooptimizeanumberofparameters,discussedbelow.Theelectrolyteprovidesfortheseparationofionictransportandelectronictransport,andinaperfectbatterythelithiumiontransportnumberwillbeunityintheelectrolyte.Thecellpotentialisdeterminedbythedifferencebetweenthechemicalpotentialofthelithiumintheanodeandcathode,¢G)-EF.Asnotedabove,thelithiumionsflowthroughtheelectrolytewhereastheelectronsgeneratedfromthereaction,Li)Li++e-,gothroughtheexternalcircuittodowork.Thus,theelectrodesystemmustallowfortheflowofbothlithiumionsandelectrons.Thatis,itmustbebothagoodionicconductorandanelectronicconductor.Asdiscussedbelow,manyelectrochemicallyactivematerialsarenotgoodelec-tronicconductors,soitisnecessarytoaddanelectronicallyconductivematerialsuchascarbon*Towhomcorrespondenceshouldbeaddressed.Phoneandfax:[phone].E-mail:[e-mail].2004,104,4271-430110.1021/cr020731cCCC:$48.50©2004AmericanChemicalSocietyPublishedonWeb09/14/2004black.Tophysicallyholdtheelectrodetogether,abinderisalsoadded.Inthesecasestheelectrochemi-calreactioncanonlyoccuratthosepointswheretheactivematerial,theconductivediluent,andelectro-lytemeet.Thus,mostelectrodesarecomplexporouscomposites.Thisreviewwillbemainlyconcernedwiththecathode.Theanode,thesourceoflithium,isnormallyagraphiticcarbonandwillbediscussedindetailbyRachidYazamiinafutureissue.Theelectrolytesolutioncommonlycomprisesalithiumsaltdissolvedinamixtureoforganicsolvents,examplesincludeLiPF6orLiBOB(theBOBistheanionwiththeboroncoordinatedbytwooxalategroups)inanethylenecarbonate/dimethylcarbonatesolvent;KangXudis-cusseselectrolyteslaterinthisissue.Althoughorganicpolymerscontaininglithiumionshavebeenstudiedforseveraldecadesaspossibleelectrolytes,theirconductivityisstilltoolow,andsotheyareonlyusedwhenaliquidisaddedtogiveaplasticizedstate.Inafewcases,solidelectrolyteshavebeenusedforafewspecializedapplicationssuchasforoilwellloggingwhereelevatedtemperaturesarefound.Thoughtheionsflowthroughtheelectrolyte,theanodeandcathodemustbephysicallyseparatedtopreventanelectricalshort.Thisisaccomplishedbyusingaporousseparatormaterial,whichallowswettingbytheelectrolyteandtheflowoflithiumionsthroughit.P.Auroradiscussesthesematerialsindetail.Formostconsumerdevices,energystorageiskey:operatingtimeiskey,sothemorethebetter,as,forexample,incellphones,laptopcomputers,