硅负极材料的相关应用介绍

寿命寿命硅负采材料SiliconanodewithlifecyclelifeProf.XinpingQiuDepartmentofChemistry,TsinghuaUniversityBeijing,100084,China3/4/2020DifficultiesforsiliconanodeapplicationLargevolumeexchangeleadtostructuralfailureofelectrodeRelativelowconductivityandrateperformanceiMEFnW0**ElectronnumberEnergydensityMolecularmassSi:4200mAh/g1Multielectronreactionmaterials3/4/2020J.R.Dahn,Electrochem.Solid-StateLett.,2001,4,A137.J.R.Dahn,J.Electrochem.Soc.2003,150,A1457.2ColossalvolumechangeChangein(a)length+andwidthx,(b)height,and(c)volumeofthea-Sitowercomparedto(d)voltagevs.AFMscannumber.SchematicdiagramoftheinsituAFMapparatus.OpticalmicrographofaLi-alloyfilmafterexpansion3/4/2020Y.Cui,Nat.Nanotechnol.,2008,3,31.|Y.Cui,NanoLett.2011,11,2949.|G.Yushin,Nat.Mater.,2010,9,353.|G.A.Ozin,Adv.Funct.Mater.2009,19,1999.|X.J.Huang,Adv.Mater.2011,23,4938.|X.P.Qiu,Electrochem.Commun.,2007,5,930.|S.M.Lee,Electrochim.Acta,2008,53,4500.|J.G.Zhang,J.Electrochem.Soc.,2010,7,A765.|J.R.Dahn,Electrochem.Solid-StateLett.,2007,10,A17.|G.Yushin,ACSAppl.Mater.Inter.,2010,11,3004.|G.Yushin,Science,2011,334,75.SibasedanodeNanomaterialsSiarrayCurrentcollectorBinder3StrategiesforsiliconanodesParticlepulverization“Astrongsizedependenceoffractureinsiliconmaterialwasdiscoveredthatthereexistsacriticalparticlesizeof∼150nmbelowwhichcrackingdidnotoccur.”[2]Sizeeffect[1]HZhang,NanoLetters2012,12,2778.;[2]XHLiu,ACSNano.2012,2,1522–15313/4/20204ElectrodeInterfaceParticle•Electroniccontact•StabilityofSEIfilm•FractureandPulverizationCurrentcollector;Binder;ArrayStabilityinSi-basedmaterial[1]LiinsertionLiextractionLongcycles3/4/20205TheexposedactivesurfaceduetothevolumechangecausecontinualformationofSEIfilmsandlowcoulombicefficiency(CE).ResearchroutesReducetheparticlesizetoaccommodateSEIfilmDesignporousorhollowstructuretobufferthevolumeexpansionCompositewithCorMetal(Cu)toincreaseelectronicconductivityandmodifytheinterfacebetweenSiandelectrolyte.InvestigatenewbinderandelectrolyteadditivessystemforSi-basedanodematerialsStabilityofSEIfilm65%SiH4+95%Ar5%H2&95%Ar450C,1h-2.5hCalcination2N2atmosphere900C,4hN2atmosphere225C,1h500C,2hHeatingunderstirringPorouscarbon80C,solventevaporationCalcination1RemovetemplateHClSiCVDPorousSi-CNanoCaCO3SucrosesolutionDepositedsiliconCarbonframeworkafter1stand2ndcalcination3/4/2020PorousSi/CcompositeSynthesisProcess3/4/2020Morphology7in1bold,1ePorousstructureofcarbonsubstratecanbeobservedfromTEMimagesAfterCVD,siliconparticlesadheretotheframeworkandporousstructurewasmaintained.Particlesizeofsiliconis~10nmandhomogeneouslydispersed.ThedepositedsiliconinPorousSi-Cisamorphous,asindicatedbytheabsenceofcrystallitesandbroaddiffuseringsintheSAEDpatterns.Incontrast,whencompositeisheatedto700°Cfor0.5h,alatticefringecorrespondingtod111=0.31nmforsiliconisseeninPorousSi-C-700.ResultsandanalysisSEMandTEMimages3/4/20208020406080100Intensity(a.u.)2theta(degree)Si/CSi/C-700Std.Siliconin1bold,1eObviouscharacteristicpeakofcrystalsiliconafterheattreatmentat700Cfor0.5hThreeobviousdiffractionpeaksaround28°,47°and56°arefoundafterheattreatment,whichcorrespondverywelltothe(111),(220)and(311)peaksofsiliconwithoutanyimpuritypeaks.Thepeakat520cm-1(indicativeofcrystallinesilicon)isnotdetectedaftersiliconCVD.Thebandscenteredaround155,474cm-1andtheweakshoulderat400cm-1aretypicalfeaturesofamorphoussiliconvibrationmodes[1].Resultsandanalysis0200400100015002000GPorousCSi/CIntensity(a.u.)Ramanshift(cm-1)DStructuralcharacterization[1]D.Aurbach,J.Phys.Chem.C,2007,111,11437.XRDpatternsandRamanspectraN2sorptionisothermsPoresizedistributionBothporouscarbonandporousSi-CshowtypeIVisotherm,whichistypicalcharacteristicofmesoporousstructureObviousdecreaseofspecificsurfacearea(SSA)andporevolumeafterSiCVDPorouscarbon:650m2/g,1.32cc/gPorousSi-C:150m2/g,0.39cc/gPoreswithdiameterof~3nmgeneratedbydecompositionofsucrosePoreswithdiameterof10~40nmduetotheremovalofCaCO3template,whichwerereducedafterSiCVDPorousStructure0.00.20.40.60.81.00100200300400500600700800900Volume@STP(ccg-1)RelativePressure,P/P0PorousCSi/C0204060801000.00.20.40.60.81.01.21.4dV/dD(ccg-1nm-1)Diameter(nm)PorousCSi/C3/4/20209Charge-DischargecurvesCyclingperformance1)2ndchargecapacity;2)VC:vinylenecarbonate0800160024000.00.51.01.52.02.53.03.5100th50th2ndPotential(vsLi/Li+)Capacity(mAhg-1)1st3/4/202010Electrochemicalperformance1stdchcapacity:2404mAh/g1stchcapacity:1541mAh/g1stcoulombicefficiency:64.1%Reversiblecapacity1:1504mAh/gCapacityretention:67%after200cyclesRecipe:PorousSi-C:CB:binder(PAA)=6:2:2;Electrolyte:1MLiPF6inEC-DMC-EMC(1:1:1vol%)with2wt%VC2;loading:0.61mg/cm2.Capacityisonlybasedonactivematerial.Currentdensity:0.1A/gfor1-2cycle,then0.5A/g;Voltage:0.05–2.0Vvs.Li050100150200050010001500200025003000NanoSiSi/CCapacity(mAhg-1)Cyclenumber80828486889092949698100C.E.(%)RatecapabilityIncreasecurrentdensityfrom0.1to2Ag-1,thespecificcapacityofSi/Ccompositeisstillabove500mAhg-1,whenthecurrentdensitychangesbackto0.1Ag-1,morethan92%ofthecapacityatthefirsttencyclesisrecoverable.3/4/202011CurrentDensity(A/g)Dis