电池的发展史记及正负极材料

BatteryUniversityonline:BriefhistoryofthebatteryFirstbattery2()2sCueCu2()2sZneZn-0.76VvsSHE0.34VvsSHETotalvoltage:1.1VEnergyStorage:Lithiumionbattery=Li+=LiPF6ChargedstateLiC6(graphiteanode)Li2O/Coo(cobaltoxideanode)AnodeCathodeFePO4cathodeCoO2cathodee-e-C(graphiteanode)Co3O4(cobaltoxideanode)LiFePO4cathodeLiCoO2cathodeDischargedstateDischargingCommontoallLiionbatteries•Conductingcurrentcollectors•Anode•Cathode•Electrolyte•SeperatorTarascon,J.M.&Armand,M.,Nature,414,(2001)Conductingcurrentcollectors•Lightweight,typicallymetallic•Chemicallyresistant•StableatcellvoltagesCourtesy:Lt.Col.F.JohnBurpoStainlesssteelanodecurrentcollectorSeperators:permeabilityandstability•Mustbeanelectronicinsulator•Mustbeionicconductor•Chemicallyresistant•StableinelectrolyteRead:Arora,P.,andAhengming,Z.,ChemicalReviews,2004,4419-4462ElectrolyteXu,K.,ChemicalReviews,20044303-4417•Theelectrolytemustbeagoodionicconductor,andanelectronicinsulator•Mustbestableatnecessarypotentialsandtemperatures•Performsminimalsidereactionswithelectrodes•MuchofbatteryfailureanddegradationiscausedbyelectrolytesidereactionsSafetyconcernswithcurrentLiionbatteriesdrivetohigherpotentialanodes•Safetyimprovements•Electrolytestabilization•Lidendriteformation…LithiumplatinganddendritesXu,K.,ChemicalReviews,20044303-4417Tarascon,J.M.&Armand,M.,Nature,414,(2001)CathodeSEIandinternalresistance•Cathodescanbefouledbydegradationofelectrolyteonthesurfaceofthematerial•ForinstanceEthylcarbonatecanformpolymericolefinsonthesurfaceoftheelectrode•TypicallytheSEIisapoorionconductorandwillincreasetheinternalresistanceofthebatteryInternalresistance•Theinternalresistanceincreasesinthebatteryovertime•Theactualvoltageoutputisneverexactlythesamewhencurrentisbeingdrawnfromthebatteryaswhenthereisnocurrentbeingdrawn•Thehighertheinternalresistanceis,thelowertheobservedvoltagewillbewhen3.02.52.01.51.00.50.0Potential(V)5040302010Time(sec)Internalresistancemeasurement•Measuredbyintentionallyshortingthebatteryusingadefinedresistor•Oncetheinternalresistanceisknown,themaximumcelloutputcanbecalculated•InternalresistanceisafunctionofSEI,electrodeconductivity,andsurfaceareaDV=1.22ViUIRRiUIRD2.978743.94sciUIRVmA0scinternalresistanceresistorvaluecurrentPotentialChangeinpotentialUinitialvoltageIshortcircuitcurrentiRRIUUDChemicalenergystorage•CellpotentialisdeterminedbythedifferenceinGibbsfreeenergyoftheLithiumintheanodeandcathode•Theelectrodesmustallowionstoflowthroughthem–Thisishelpedbyusinglayeredstructures–Makingnanoscalematerials–Coatingorpercolatingthesystemwithconductingmaterial•Howdowemeasurebatterymaterials?–SpecificCapacity–Energy–Power–Ragoneplot•GalvanostaticmeasurementGEFDChemistriesofelectrodes•MostcommonelectrodesystemisthatofLiCoO2andgraphitecharge212dischargexLiCoOLiCoOxLixecharge2126discharge6xxLiCoOCLiCoOLiCdischarge6charge6xxLixeCLiC3.8-3.9Vvs.Li0.1Vvs.Li3.7VtotalCharacterization•Thecellvoltageistheaveragevoltageofthedischargecycle•LiCoO2hasanaveragedischargevoltageof3.7VFromNokia1.Ohzuku,T.;Brodd,R.J.,J.PowerSources2007,174,(2),449-456;2.Amatucci,G.G.;Pereira,N.,J.FluorineChemistry2007,128,(4),243-262;3.Howard,W.F.;Spotnitz,R.M.,J.PowerSources2007,165,(2),887-891.OtherCathodeMaterialsLi2MnSiO4LiFePO4Capacitycalculationonatypicalanode895484sec11000113600sec1240.8eXAhourmAmoleXXXmoleAmpgCapacitycalculatedforcobaltoxidetobe881mAh/garg0342arg8843DischeCheLiCoOeLiOCoVolumechangesinbatteryelectrodes•Metallicanodesbehaveentirelydifferentfromtypicaloxideanodes•Typicallyametalwillformanalloywithlithiumbyformallyreducingthelithium•Failuresinmetallicanodesareusuallyduetovolumechanges•Volumechangesliterallycausefortheelectrodetobedestroyed•Mostalloyingelectrodesarenotstableformorethanacouplecharge/dischargecyclesTirado,J.L.,MaterialsScienceandEngineeringR40,2003,103-136Goldormetallicanodes•Auanodecanalloywithlithium(thisisnotthesameasgraphitebeingplatedwithlithium•Phasesofgold/lithiumalloys•AgandAucanhaveseveralalloyphases(AgLi9orAu4Li15)•Therearemanysystemsthatcanformalloyswithlithium(tinorsilicon)butthevolumetricexpansionissogreatthattheelectrodeisunstable•TheseelectrodesarespecialinthattheyactuallycatalyzethereductionofLi+toLio•Thiscatalysishasvariouspotentialsvs.Limetal,typicallyaround0.7V•AuorAg:capableofalloyingwithLiuptoAgLi9andAu4Li15atverynegativepotential•Advantagesinminimizingcellvoltagereduction•HightheoreticalcapacityTaillades,2002,SoldStateIonics•Plateaus:–0.2and0.1V/discharge–0.2and0.45V/charge•Capacityfrom2ndcycle–501mAh/g[AuLi3.69]Diameter:~40nm,freesurfaceAu0.9Ag0.1Discharge/chargecurvesfromthefirsttwocyclesAu0.5Ag0.5Au0.67Ag0.33GradualchangesinpotentialduringdischargeCapacityat2ndcycle:499forAu0.5Ag0.5459forAu0.67Ag0.33Au0.9Ag0.1CurveshapesimilarwithAuCapacityat2ndcycle:439CalculatingcapacityforGoldAnodedischargechargexAuxLiAuLiDischarge415Charge4Au+15Li15AuLieCap