吴宇平-锂离子电池安全问题解决的关键-聚合物电解质

锂离子电池安全问题解决的关键-聚合物电解质吴宇平复旦大学化学系新能源与材料实验室上海200433Tel/Fax:[phone]Email:[e-mail]@锂离子电池新材料国际论坛深圳，2010年7月29日NEML,FudanUni.Outline•Introduction•GPEsbasedoncrosslinkedstructure•PorousGPEsbasedonP(AN-MMA)•GPEsbasedonP(VDF-HFP)•SandwichedGPEs•OtherGPEssuchasstick-likeones•Summary•AcknowledgementNEML,FudanUni.1.IntroductionY.P.Wuetal.,Lithiumionbatteries:Practice&applications,ChemicalIndustryPress,2004.chargedischargeLi+/e-Li+/e-Anode:6C+xLi++xe-LixC6Cathode:LiCoO2Li1-xCoO2+xLi++xe-Total:6C+LiCoO2Li1-xCoO2+LixC6Anode:graphiticcarbonCathode:LiCoO2ChargeDischargeChargeDischargeChargeDischargeNEML,FudanUni.DevelopmentofLIBs：Intheearlyof1990s,lithiumionbatteryformallycameintobirth,andithasbeenappliedinalotoffields.Characteristicsoflithiumionbattery•Highoutputvoltage(average3.6V)andpower•Highenergydensity(UR18650:450Wh/cm3,150Wh/kg)•Lowselfdischarge(10%/month)•Nomemoryeffect•Longcyclelife(1000times)•Highratecapability(1C)•Highcoulombefficiency(near100%exceptinthe1stcycle)•Easytomeasuretheresidualcapacity•Maintenancefree•Noenvironmentalpollution(greenbattery)•Wideworktemperature(-25-+45oC,extendedto–40–70oC)NEML,FudanUni.•Furtherapplicationsoflithiumionbatteries:HEV,EV…Ratecapability,Price&SafetyY.P.Wuetal.,Lithiumionbatteries:Practice&applications,ChemicalIndustryPress,2004.NEML,FudanUni.√Ratecapability:anodeandcathode1stcycle:348mAh/g500thcycle:301mAh/g86%2C(348mAh/g),0.08C(357mAh/g)=97.5%SSG:Goodsuccessinmarket,verygoodproductovertheworld.01002003004005002.02.22.42.62.83.03.23.43.63.84.0Voltage(V)Capacity(mAh)1CchargeDischarge1235820181615131210(a)1Crate(b)2CrateNEML,FudanUni.Excellentcycling:Lowcost.Anode:SSGbasedonnaturalgraphiteCathode:LiFePO4andLiMn2O4√Price:anodeandcathodeY.P.Wuetal.,J.PowerSources,162:663(2006);J.Appl.Electrochem.,36,1307(2006).0100200400300Capacity(mAh/g)1002003004005000Cyclenumber500NEML,FudanUni.Safety???0.438MpacksSonycellinnotePCJun.2008-HPnotePCMar.,20100.055362MpacksSonycellinnotePCJul.20100.21MpacksNEC-TokincellinKyoceracellularphoneMar.200846MpacksPanasoniccellinNokiacellularphoneAug.20070.07MpacksNEC-TokincellinKDDIcellularphoneJun.20070.13MpacksNEC-TokincellinWelcommcellularphoneJun.20070.2MpacksSanyocellinLenovonotePCMar.20071.3MpacksSanyocellinMitsubishicellularphoneDec.20063.7MpacksSonycellinToshiba&FujitsunotePCOct.20061.8MpacksSonycellinApplenotePCAug.20064.1MpacksSonycellinDellnotePCAug.2006RecallscaleAccidentdeviceDateRecentrecallannouncementofLIBsTheserecallscalessuggesttheaccidentpossibilityisppmorder.RecentrecallannouncementofLIBsRecentrecallannouncementofLIBsNEML,FudanUni.SafetyproblemsforEVsnotePC:40Wh(=5Ahx8V)iMiEV:16000Wh(=50Ahx330V)Fig.ApplicationmapofLIBs.Accidentriskisinproportiontothesquareofthetotalcellenergy.CurrentLargecapacity10mA100mA1A10A100A1001010.110mAh100mAh1Ah10Ah100Ah1kAhHighpowerMP3MusicPlayerCellularVCRNotePCAIBOCordlesscleanerUPSPriusE-BikeEVSmartgridNEML,FudanUni.Howtosolvethesafetyproblem•Additives:flameretardantsReliability???•Polymerelectrolytes•Inorganicsolidelectrolytes•AqueousrechargeablelithiumbatteriesSolidpolymerelectrolytesGelledpolymerelectrolytesNEML,FudanUni.AdvantagesofsolidpolymerelectrolyteHighambientionicconductivityChemicalstabilityElectrochemicalstabilityMechanicalstrengthLowglasstransitiontemperatureRequirementsforsolidpolymerelectrolytesHigherenergydensityFlexibilityNoseparatorNoleakageNEML,FudanUni.Poly(ethyleneoxide)(PEO)-basedSPEvTgisalittlehigh(-50℃)vLowambientionicconductivityvPoormechanicalpropertiesFrom1973,P.V.Wrightetal.•Possessdonoroxygenatoms•ExcellentsolventforalkalimetalionsProblems:NEML,FudanUni.MethodstomodifyPEO-basedelectrolytesvCopolymerizingvBlendingvCrosslinkingvFormingorganic-inorganiccompositesvAddingnanofillersv……Ionicconductivity@RTisbelow10-4S/cm,notusefulforapplications.NEML,FudanUni.Gelledpolymerelectrolytes(GPEs)•Goodsafety•Highionicconductivity•Goodsurfaceperformancewithelectrodes.1.21.00.80.60.40.2030405060708090100110Temperature/oCLEsGPEsNEML,FudanUni.•GPEs:basedonPEO,PAN,PMMA,PVDF,P(VDF-HFP)…Mainfactors:•Porousstructure•Mechanicalstrength•ProcessingperformanceContradictingNEML,FudanUni.2.GPEsbasedoncrosslinkedstructurePolymerelectrolytesbasedonpoly(ether-urethane)network:+PEG→PUN-basedGPEsNetworkstructure(goodcompatibilitywithLEs)CH3CH2CCH2OCONHNCOCH3CH2OCONHNCOCH3CH2OCONHNCOCH3TMP-TDI()Y.P.Wuetal.,Electrochem.Commun.,5,1025(2003).NEML,FudanUni.Nanofillers•uSiO2ofaverageparticlesize20nmwiththenativehydroxylgroupsatthesurface•mSiO2ofaverageparticlesize12nmwithhydrophobicgroupsatthesurfaceFig.XRDpatternsof(a)pristinePUN/LiClO4SPE;(b)PUN/uSiO2/LiClO4CSPE(theamountofuSiO2basedonPUNis1.25wt%);and(c)PUN/mSiO2/LiClO4CSPE(theamountofmSiO2basedonPUNis1.67wt%)NEML,FudanUni.Fig.IonicconductivityversustheadditionamountuSiO2andmSiO2fillersforPUN/filler/LiClO4CSPEsat30oC([EO]/[Li]=12.5).Fig.Vogel-Tammann-Fulcherplotsofionicconductivityfor(a)pristinePUN/LiClO4SPE,(b)PUN/uSiO2/LiClO4CSPE(theamountofuSiO2basedonPUNis1.25wt%),and(c)PUN/mSiO2/LiClO4CSPE(theamountofmSiO2basedonPUNis1.67wt%).678910111