高容量锂离子电池电极材料研究的新进展课件

ExplorationresearchofnewcathodematerialswithhighcapacityforLi-ionbatteryYongYangStateKeyLabofPhysicalChemistryofSolidSurface,XiamenUniversityChinaWhat’arethemajorplayersofthecathodematerialsElectrodematerialsHighenergydensityHighpowerdensityLayeredoxidecathodematerialsPolyanion:LFePO4,Spinel,LiMn2O4﹛HighenergydensityLi2FeMnSiO4;Organic-typeFluorides…Furtherimprovementoflayeredoxide-basedcathodematerials1)Nickel-basedlayeredcathodematerials:Lattice-dopingSurfacecoating1)H.S.Liu,etal;ElectrochimicaActa,2004,49:1151-1159;SolidStateIonics,2004,166:317-3252)Z.R.Zhang,etal;JPowerSources,2004,129(1):101-106;J.Phys.Chem.B;2004,108,17546-175522)Li-richLi-Ni-Co-Mn-Osystem;

Verypromisingsystem,stillmorestudyareneeded.E.g.firstcycleefficiency,ratecapability,safetyissues,howchoosesuitableanodesystems….LayeredOxide-typeCathodeMaterialsHighenergydensitybatteriesLayeredoxidecathodematerialsLi2MnO3.LiNixCoyMn1-x-yO2:~270mAh/gorevenhigher,Gasevolution,e.g.O2,CO2HighcapacitycathodematerialsChargingtohighvoltageIn-situElectrochemicalMassspectroscopictechniquesandItsuseinLi-ionbatteriesAlF3coatinglayerprovidesabufferlayertomakeoxygenatomswithhighactivitycombinetogethertoformO2moleculeswithlowoxidationcapabilitytoelectrolytes.1/45timesAdvantages:LowcostexcellentthermalstabilitynooxygenevolvedatlowamountLi+intercalatedDisadvantages:LowercapacityandlowelectronicconductivityPhosphateshouldbedevelopedasHighPowerDensityandSafeCathodeMaterialsPolyanioncompounds(i.e.LiFePO4)withstableframeworkisoneoftheexcellentcandidateasnewgenerationcathodematerialsinlithium-ionbatteriesWhydowechooseSilicates???orthosilicatematerials(Li2MSiO4):Twolithiumionsshouldbereversibleextractedorinsertedinprinciplewithoutdistinctivelychangesofthecrystalstructure.Theo.(mAhg-1)Exp.(mAhg-1)LiCoO2274140LiNiO2275200LiNi1-xCoxO2275170~180LiNi1/2Mn1/2O2280180~190LiFePO4170150Li2FeSiO4331165

Li2MnSiO4333209(1stcycle)Li2MnxFe1-xSiO4332235(x=0.5)Anovelcathodematerialswithmorethanoneelectronexchange:Li2MnSiO4

RietveldplotofLi2MnSiO4/Ccomposite.Y.X.Li,Z.L.Gong,Y.Yang;J.PowerSources,174(2),528-532,2007

Y.Yang,Y.X.Li,Z.L.Gong;ChinesePatentCN2Li2MnSiO4正极材料循环性能的研究CyclicstabilityofLi2MnSiO4materialispoor!

CyclicperformanceofimprovedLi2Mn0.5Fe0.5SiO4

Currentdensity：10mA/g(~C/16)，Temperature：30oCCapacity（mAh/g)ThechangesinValenceofMnionsLi2MnSiO4209+2+3.25Li2Mn0.5Fe0.5SiO4235+2

+3.84EvidenceforfadingmechanismofLi2MnSiO4870cm-1SiO44-SiO44-SiO44-SiO32-SolidMAS7LiNMRofLi2MnSiO4atdifferentchargedstatesFromex-situNMRspectra,itisproposedthattherateofdeintercalationofLi+atdifferentsitesaredifferent,andsomeLi2SiO3arenewlyformedXRDpatternofLi2Fe0.5MnSiO4SEMimagesofLi2Fe0.5Mn0.5SiO4StructureandmorphologyofLi2Fe0.5Mn0.5SiO4/CElectrochemicalperformancesofLi2Fe0.5Mn0.5SiO4Theinitialtwocyclesat5mA/gbetween1.5and4.8V.Theinitialtwocyclesat10mA/gbetween1.5and4.8V.Theinitialtwocyclesat150mA/gbetween1.5and4.8V.CyclicperformancesofLi2Fe0.5Mn0.5SiO4at5,10and150mA/g,andLi2MnSiO4at5mA/gIn-situFeK-edgeXANESspectraduringthefirstchargingprocessIn-situMnK-edgeXANESspectraduringthefirstchargingprocessEvolutionofabsorptionedgeofFeandMnofLi2Mn0.5Fe0.5SiO4inthefirstcharginganddischargingprocesses.Structure,MorphologyandMicrostructureofCarbon-coatedLi2FeSiO4NanostructuredcharacteristicoftheLi2FeSiO4makeitashigh-ratecathodematerialsfeasibleTheinverseofthemagneticsusceptibilitywithtemperatureagreeswellwithparamagnetismforpuresample.ThearrowpointouttheanomaliescharacteristicsofanantiferromagneticorderingofLi2FeSiO4belowTN=20K.ThecurveagreewellwithCurie-Weisslawinthewholeparamagneticregion.ElectrochemicalperformanceoftheLi2FeSiO4cathodesatdifferentcycles1.5–4.8VversusLi+/Li;1/16CZ.L.Gong,Y.X.Li,G.N.He,J.Li,Y.Yang*

Electrochem.SolidStateLett.,11,A60-63(2008).

ExcellentcyclicstabilityofLi2FeSiO4ExcellentthermalstabilityNoextraheatgiveoffduringheatingprocess!!

Atoursynthesisconditions,twomodificationsofLi2CoSiO4(βⅡ,andβⅠ)whicharederivativesoflowtemperatureLi3PO4wereobtained.

a:βⅡ;Oorthorhombicandspace-groupPmn21.b:βⅠorthorhombicTheXRDprofilesoftheLi2CoSiO4powerspreparedatdifferentconditions.Co-silicates--Li2CoSiO4

L.Gong,Y.X.Li,Y.Yang;JPowerSources,2007,174(2),524-527,S.Q.Wu,J.H.Zhang,Z.Z.ZhuandY.Yang,Curr.Appl.Phys.2007,7,611Thetemperaturedependenceoftheinversemolarmagneticsusceptibility1/χmforLi2CoSiO4powerspreparedat873K.ThemagnetizationcurvesM(H)at2KforLi2CoSiO4powerspreparedat873K.

MagneticpropertyGalvanostaticcharge–dischargecurvesforLi2CoSiO4-basedcathodesatcurrentrate16mA/g.

Electrochemicalperformancespace-group:Pmn21SiO4

-MO4LiO4SiO4

-MO4CorrugatedlayerFirst-principlesinvestigationsonthestructuralandelectronicpropertiesStructureofLi2MSiO4Reference:S.Q.Wu,etal;ComputationalMaterialsScience,2009,44,1243-1251O–Co-OO–Si-OConclusions

AseriesofsilicatescathodematerialssuchasLi2FeSiO4,LiFexMn1-xSiO4,Li2CoSiO4withandwithoutcarboncoatinghavebeensynthesized,someofthemcouldachievemorethan1-1.6Li+reversibleexchange.e.g.Li2Mn0.5Fe0.5SiO4with235mAh/ghasbeenachieved.Wehavemadeacarbon-coatednanostructuredLi2FeSiO4materialwithexcellentrateperformance,itshowsapromiseascathodematerialsforhigh-powerlithium-ionbatteries.Phase-pureLi2CoSiO4hasbeenpreparedsuccessfullyanditsphysicalpropertiesandelectrochemicalperformancewerecharacterized.SomecommentsWe