硅負(fù)極材料的相關(guān)應(yīng)用介紹課件

壽命壽命硅負(fù)采材料

Silicon

anode

with

life

cycle

lifeProf.XinpingQiuDepartmentofChemistry,TsinghuaUniversityBeijing,100084,China壽命壽命硅負(fù)采材料

Siliconanodewithl12/13/2022DifficultiesforsiliconanodeapplicationLargevolumeexchangeleadtostructuralfailureofelectrodeRelativelowconductivityandrateperformanceElectronnumberEnergydensityMolecularmassSi:4200mAh/g2Multielectronreactionmaterials12/12/2022Difficultiesforsil12/13/2022J.R.Dahn,Electrochem.Solid-StateLett.,2001,4,A137.J.R.Dahn,J.Electrochem.Soc.2003,150,A1457.3ColossalvolumechangeChangein(a)length+andwidthx,(b)height,and(c)volumeofthea-Sitowercomparedto(d)voltagevs.AFMscannumber.SchematicdiagramoftheinsituAFMapparatus.OpticalmicrographofaLi-alloyfilmafterexpansion12/12/2022J.R.Dahn,Electroch12/13/2022Y.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.SibasedanodeNanomaterialsSiarrayCurrentcollectorBinder4Strategiesforsiliconanodes12/12/2022Y.Cui,Nat.NanotecParticlepulverization

“Astrongsizedependenceoffractureinsiliconmaterialwasdiscoveredthatthereexistsacriticalparticlesizeof～150nmbelowwhichcrackingdidnotoccur.”

[2]Sizeeffect[1]HZhang,NanoLetters2012,12,2778.;[2]XHLiu,ACSNano.2012,2,1522–153112/13/20225ElectrodeElectroniccontactInterfaceStabilityofSEIfilmParticleFractureandPulverizationCurrentcollector;Binder;ArrayStabilityinSi-basedmaterial?[1]Particlepulverization“AstrLiinsertionLiextractionLongcycles12/13/20226TheexposedactivesurfaceduetothevolumechangecausecontinualformationofSEIfilmsandlowcoulombicefficiency(CE).ResearchroutesReducetheparticlesizetoaccommodateSEIfilmDesignporousorhollowstructuretobufferthevolumeexpansionCompositewithCorMetal(Cu)toincreaseelectronicconductivityandmodifytheinterfacebetweenSiandelectrolyte.InvestigatenewbinderandelectrolyteadditivessystemforSi-basedanodematerialsStabilityofSEIfilmLiinsertionLiextractionLong75%SiH4+95%Ar5%H2&95%Ar450C,1h-2.5hCalcination2N2atmosphere900C,4hN2atmosphere225C,1h500C,2hHeatingunderstirringPorouscarbon80C,solventevaporationCalcination1RemovetemplateHClSiCVDPorousSi-C

NanoCaCO3

SucrosesolutionDepositedsiliconCarbonframeworkafter1stand2ndcalcination12/13/2022PorousSi/CcompositeSynthesisProcess75%SiH4+95%ArCalcination12/13/2022Morphology8in1bold,1ePorousstructureofcarbonsubstratecanbeobservedfromTEMimagesAfterCVD,siliconparticlesadheretotheframeworkandporousstructurewasmaintained.Particlesizeofsiliconis~10nmandhomogeneouslydispersed.ThedepositedsiliconinPorousSi-Cisamorphous,asindicatedbytheabsenceofcrystallitesandbroaddiffuseringsintheSAEDpatterns.Incontrast,whencompositeisheatedto700°Cfor0.5h,alatticefringecorrespondingtod111=0.31nmforsiliconisseeninPorousSi-C-700.ResultsandanalysisSEMandTEMimages12/12/2022Morphology8in1bo12/13/20229in1bold,1eObviouscharacteristicpeakofcrystalsiliconafterheattreatmentat700Cfor0.5hThreeobviousdiffractionpeaksaround28°,47°and56°arefoundafterheattreatment,whichcorrespondverywelltothe(111),(220)and(311)peaksofsiliconwithoutanyimpuritypeaks.Thepeakat520cm-1(indicativeofcrystallinesilicon)isnotdetectedaftersiliconCVD.Thebandscenteredaround155,474cm-1andtheweakshoulderat400cm-1aretypicalfeaturesofamorphoussiliconvibrationmodes[1].ResultsandanalysisStructuralcharacterization[1]D.Aurbach,J.Phys.Chem.C,2007,111,11437.XRDpatternsandRamanspectra12/12/20229in1bold,1eResuN2sorptionisothermsPoresizedistributionBothporouscarbonandporousSi-CshowtypeIVisotherm,whichistypicalcharacteristicofmesoporousstructureObviousdecreaseofspecificsurfacearea(SSA)andporevolumeafterSiCVDPorouscarbon:650m2/g,1.32cc/gPorousSi-C:150m2/g,0.39cc/gPoreswithdiameterof~3nmgeneratedby

decompositionofsucrosePoreswithdiameterof10~40nmduetotheremovalofCaCO3template,whichwerereducedafterSiCVDPorousStructure12/13/202210N2sorptionisothermsPoresizeCharge-DischargecurvesCyclingperformance1)2ndchargecapacity;2)VC:vinylenecarbonate12/13/202211Electrochemicalperformance1stdchcapacity:2404mAh/g1stchcapacity:1541mAh/g1stcoulombicefficiency:64.1%Reversiblecapacity1:1504mAh/gCapacityretention:67%after200cyclesRecipe:PorousSi-C:CB:binder(PAA)=6:2:2;Electrolyte:1MLiPF6inEC-DMC-EMC(1:1:1vol%)with2wt%VC2;loading:0.61

mg/cm2.Capacityisonlybasedonactivematerial.Currentdensity:0.1A/gfor1-2cycle,then0.5A/g;Voltage:0.05–2.0Vvs.LiCharge-DischargecurvesCyclingRatecapabilityIncreasecurrentdensityfrom0.1to2Ag-1,thespecificcapacityofSi/Ccompositeisstillabove500mAhg-1,whenthecurrentdensitychangesbackto0.1Ag-1,morethan92%ofthecapacityatthefirsttencyclesisrecoverable.12/13/202212CurrentDensity(A/g)Dischargecapacity(mAh/g)Chargecapacity(mAh/g)Coulombicefficiency(%)0.192386293.40.562962699.51.046146099.72.03113111000.176675798.9ResultsandanalysisRatecapabilityIncreasecurrenNyquistplotofSi-Ccompositeattheendofdischargeafterdifferentcyclesin1bold,1eElectrochemicalimpedancespectra(EIS)measurementina5.0mVACvoltagesignalinthe105-0.02Hzfrequencyrange.BeforeeachEIStest,theelectrodesweredischargedto0.01Vgalvanostaticallyandthenremainedatopen-circuitforatleast2htostabilizetheirpotential.Theconstancyofthecharacteristicfrequency(20Hz,from30-60cycles)suggeststhatthekineticsofthechargetransferreactiondoesnotvaryuponcycling.Evolutionoftheresistanceinmid-frequencyregion(inset)showsanincreaseinfirst5cyclesthenreduceandmaintainaround40Ohminlatercycles.Resultsandanalysis12/13/202213EIStest[1]D.Guyomard,J.Mater.Chem.,2011,21,6201.NyquistplotofSi-CcompositeSEIfilmwithcyclingSuperficialandcross-sectionalSEMimagesofourcompositeaftera),b)10cycles;c),d)20cycles;e),f)50cyclesandg),h)commercialSimaterialafter50cycles.a)b)d)c)h)g)f)e)PorousstructureofoursynthesizedcompositestillmaintainsaftercyclingandSEIfilmisonlyobservedattheexternalsurfaceofthesiliconparticlewithoutobviousincrassation.IncommercialSimeasurements,excessiveSEIfilmisfoundafter50cycles,whichisunabletobedistinguishedfromSinanoparticles.12/13/202214SEIfilmwithcyclingSuperficiMaterialsaftercycling[1]Y.Cui,NanoLett.10(2010)1409Si/Cafter50cyclesa)SEMandb)TEMimageofSi/Ccompositeattheendof50thcycle;

thecorrespondingelementalmappingofc)carbonandd)silicon.1mMofaceticacidwasusedtoremovetheSEIfilm[1].Porouscarbonstructureismaintained,nanosiliconparticlesaround10nmdoesnotshowaggregationandrupture.Resultsandanalysisa)b)c)d)C-KSi-K12/13/202215Materialsaftercycling[1]Y.SEIconfinementSchematic12/13/202216SEIfilmformsinsidetheporesduetothelowelectrochemicalpotentialoflithiuminsertioninfirstfewcycles.Whentheporesarefullfilled,SEIfilmisconfinedbythewallofcarbonsubstrate,whichpreventtheinternalsiliconparticlefrombeingexposedintheelectrolyte.ResultsSEIconfinementSchematic12/12/12/13/202217SchematicofsynthesisAdvantage:1.EasytosynthesisandregulateaccordingtocommercialCaCO3template2.Hollowstructurewithreservevolumecanaccommodatelargevolumechanges3.Interconnectednanosiliconmeansmoreactiveconductivecontact.NanoCaCO3SiliconlayerLegend:HollowsiliconPurificationbyHFacid(10wt%)5%SiH4+95%Ar400-500C,1h-2.5hSiCVDTemplateremovalbyHClacid(2wt%)12/12/202217Schematicofsynth12/13/202218ImagesandpatternsMorphologyResultsa)TEMimagesofnanoCaCO3template;b)SEMimagesofHSA-10(insetisatlowmagnification);TEMimagesofc)HSA-10,e)HSA-15,f)HSA-20;d)thecorrespondingSAEDpatternofHSA-10.Amorphoushollowsiliconmaterialwithdifferentshellthicknesswaspreparedabcdef12/12/202218Imagesandpattern12/13/202219ImagesandpatternsStructuralcharacterizationbcCharacteristicpeaksofcrystallinesilicon(PDF#65-1060)around28°,47°and56°areabsent,whichcorroboratethestatementofsiliconisamorphous.Thefirstmain3/2-1/2doublet(thespin-orbitsplittingis0.6eVandtheintensityratiois3:1),locatedat99.1-99.7eVcorrespondstoSi0(75%content).Thecomponentlocatedathigherbindingenergy(100.0eV)isassociatedwithSiOxformedatthesurfaceofHSAwithaproportionof25%.Resultsandanalysis12/12/202219Imagesandpattern12/13/202220ResultsandanalysisThenitrogenadsorption/desorptionisothermsofHSAsamplesshowasharpcapillarycondensationstepathighrelativepressures(P/P0=0.85-0.99),indicatingtheexistenceoflargepores.Correspondingporesizedistributesmainlyintherangeof20nmand100nm,whichisattributedtotheremovalofsite-occupyingnanoCaCO3.IsothermandPoresizedistributionPorousStructureSampleSpecificsurfacearea(m2g-1)Porevolume(ccg-1)HSA-1050.40.983HSA-1538.60.221HSA-2032.70.09112/12/202220Resultsandanalys12/13/202221CyclingperformanceCycleperformanceTestconditionsRecipe:HS:CB:binder(PAA)=6:2:2Electrolyte:1MLiPF6inEC-DMC-EMC(1:1:1vol%)with2wt%VC;Loading:0.4-0.6mgcm-2

Currentdensity:0.1A/gfor1-3cycle,then0.4A/g;Voltage:0.02–1.50Vvs.LiResultsHSA-10givesthehighestcapacityretention(91%)in100cyclesandcorrespondingreversiblecapacityis~980mAhg-1.Whenincreasetheshellthicknessofsilicon,reversiblecapacityincreases(980mAhg-1ofHSA-15and1133mAhg-1ofHSA-20after100cycles)butthecapacityretentiondecreasesobviously(76%ofHSA-15and73%ofHSA-20)Electrochemicalperformance12/12/202221CyclingperformancMaterialsaftercycling[1]Y.Cui,NanoLett.10(2010)1409HAS-10after50cyclesa)SEMimageofHSA-10after100cycles;b)SEMimageofHSA-10after100cycleswithoutSEIfilm;c),d)TEMimageofHSA-10after100cycleswithoutSEIfilmatdifferentmagnification.Aggregatedsecondaryparticles(Fig.c)and~10nmsiliconshellstructure(Fig.b&d)weremaintainedwithoutfractureofthehollowspheres.Resultsandanalysis12/13/202222abcdMaterialsaftercycling[1]Y.EIStest12/13/202223StableinterfaceandsmallerresistanceNyquistplotofSi-Ccompositeattheendofdischargeafterdifferentcyclesin1bold,1eElectrochemicalimpedancespectra(EIS)measurementina5.0mVACvoltagesignalinthe105-0.02Hzfrequencyrange.BeforeeachEIStest,theelectrodesweredischargedto0.01Vgalvanostaticallyandthenremainedatopen-circuitforatleast2htostabilizetheirpotential.Evolutionoftheresistanceinmid-frequencyregionmaintains~20OhmduringcyclingwhichislowerthanSi/CcompositeandnanoSimaterial.ResultsandanalysisEIStest12/12/202223StableintDSCTest12/13/202224StableSEIstructureofsiliconfoamDSCheatingcurvesin1bold,1eCurrentdensityaround0.1mA/gwasappliedtolithiatetheSiactivematerial.Afterthevoltagereached1mV,thecellswereremainedatopen-circuitfor2hthencarefullyopenedinaglovebox.TheelectrodewassoakedinDMCandthendriedundervacuumovernight.MeasurementswereconductedwithaDSC1(METTLERTOLEDO)atatemperaturerampof2?Cmin-1(30-300?C)usinghermetichigh-pressureDSCpans.TheDSCsignalat86-100?Cisvisibleforallofthecurves.Byanalogywithlithiatedgraphite,whichthermalstabilityiswellstudied,itisreasonabletosuggestthatmetastableSEIlayercomponentsaretransformedat86-100?C.ResultsandanalysisDSCTest12/12/202224StableSEIHollowsiliconalveolimaterialissynthesizedusingafacileprocessincludingchemicalvapordepositionandtemplatemethod.Morphology,primaryparticlesizeandthicknessofsiliconshellcanbepreciselycontrolledbytheinitialsizeofnanoCaCO3templateandtheparametersofCVDprocess.FreevolumeinthishollowstructureprovidesenoughspacetoaccommodatethevolumechangeinLi-Sialloyinganddealloyingreactions.Hencethismaterialexhibitsexcellentcyclingstabilitythatreversiblecapacityis~1000mAhg-1(91%capacityretention)after100cycles.Thecoulombicefficiencyduringcyclingmaintainsabove99.5%whichisbenefitforlongcyclelifeandhollowsiliconshellstructureismaintainedaftercyclingwhichindicatesthematerialisstableandreversible.12/13/202225SummaryHollowsiliconalveolimateriaThanksforyourattention!12/13/2022IBA

2014

Conference26AcknowledgementsStateKeyBasicResearchProgrammofPRC(2013CB934000),BeijingNaturalScienceFundation(2120001)Thanksforyourattention!12/1壽命壽命硅負(fù)采材料

Silicon

anode

with

life

cycle

lifeProf.XinpingQiuDepartmentofChemistry,TsinghuaUniversityBeijing,100084,China壽命壽命硅負(fù)采材料

Siliconanodewithl12/13/2022DifficultiesforsiliconanodeapplicationLargevolumeexchangeleadtostructuralfailureofelectrodeRelativelowconductivityandrateperformanceElectronnumberEnergydensityMolecularmassSi:4200mAh/g28Multielectronreactionmaterials12/12/2022Difficultiesforsil12/13/2022J.R.Dahn,Electrochem.Solid-StateLett.,2001,4,A137.J.R.Dahn,J.Electrochem.Soc.2003,150,A1457.29ColossalvolumechangeChangein(a)length+andwidthx,(b)height,and(c)volumeofthea-Sitowercomparedto(d)voltagevs.AFMscannumber.SchematicdiagramoftheinsituAFMapparatus.OpticalmicrographofaLi-alloyfilmafterexpansion12/12/2022J.R.Dahn,Electroch12/13/2022Y.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.SibasedanodeNanomaterialsSiarrayCurrentcollectorBinder30Strategiesforsiliconanodes12/12/2022Y.Cui,Nat.NanotecParticlepulverization

“Astrongsizedependenceoffractureinsiliconmaterialwasdiscoveredthatthereexistsacriticalparticlesizeof～150nmbelowwhichcrackingdidnotoccur.”

[2]Sizeeffect[1]HZhang,NanoLetters2012,12,2778.;[2]XHLiu,ACSNano.2012,2,1522–153112/13/202231ElectrodeElectroniccontactInterfaceStabilityofSEIfilmParticleFractureandPulverizationCurrentcollector;Binder;ArrayStabilityinSi-basedmaterial?[1]Particlepulverization“AstrLiinsertionLiextractionLongcycles12/13/202232TheexposedactivesurfaceduetothevolumechangecausecontinualformationofSEIfilmsandlowcoulombicefficiency(CE).ResearchroutesReducetheparticlesizetoaccommodateSEIfilmDesignporousorhollowstructuretobufferthevolumeexpansionCompositewithCorMetal(Cu)toincreaseelectronicconductivityandmodifytheinterfacebetweenSiandelectrolyte.InvestigatenewbinderandelectrolyteadditivessystemforSi-basedanodematerialsStabilityofSEIfilmLiinsertionLiextractionLong335%SiH4+95%Ar5%H2&95%Ar450C,1h-2.5hCalcination2N2atmosphere900C,4hN2atmosphere225C,1h500C,2hHeatingunderstirringPorouscarbon80C,solventevaporationCalcination1RemovetemplateHClSiCVDPorousSi-C

NanoCaCO3

SucrosesolutionDepositedsiliconCarbonframeworkafter1stand2ndcalcination12/13/2022PorousSi/CcompositeSynthesisProcess75%SiH4+95%ArCalcination12/13/2022Morphology34in1bold,1ePorousstructureofcarbonsubstratecanbeobservedfromTEMimagesAfterCVD,siliconparticlesadheretotheframeworkandporousstructurewasmaintained.Particlesizeofsiliconis~10nmandhomogeneouslydispersed.ThedepositedsiliconinPorousSi-Cisamorphous,asindicatedbytheabsenceofcrystallitesandbroaddiffuseringsintheSAEDpatterns.Incontrast,whencompositeisheatedto700°Cfor0.5h,alatticefringecorrespondingtod111=0.31nmforsiliconisseeninPorousSi-C-700.ResultsandanalysisSEMandTEMimages12/12/2022Morphology8in1bo12/13/202235in1bold,1eObviouscharacteristicpeakofcrystalsiliconafterheattreatmentat700Cfor0.5hThreeobviousdiffractionpeaksaround28°,47°and56°arefoundafterheattreatment,whichcorrespondverywelltothe(111),(220)and(311)peaksofsiliconwithoutanyimpuritypeaks.Thepeakat520cm-1(indicativeofcrystallinesilicon)isnotdetectedaftersiliconCVD.Thebandscenteredaround155,474cm-1andtheweakshoulderat400cm-1aretypicalfeaturesofamorphoussiliconvibrationmodes[1].ResultsandanalysisStructuralcharacterization[1]D.Aurbach,J.Phys.Chem.C,2007,111,11437.XRDpatternsandRamanspectra12/12/20229in1bold,1eResuN2sorptionisothermsPoresizedistributionBothporouscarbonandporousSi-CshowtypeIVisotherm,whichistypicalcharacteristicofmesoporousstructureObviousdecreaseofspecificsurfacearea(SSA)andporevolumeafterSiCVDPorouscarbon:650m2/g,1.32cc/gPorousSi-C:150m2/g,0.39cc/gPoreswithdiameterof~3nmgeneratedby

decompositionofsucrosePoreswithdiameterof10~40nmduetotheremovalofCaCO3template,whichwerereducedafterSiCVDPorousStructure12/13/202236N2sorptionisothermsPoresizeCharge-DischargecurvesCyclingperformance1)2ndchargecapacity;2)VC:vinylenecarbonate12/13/202237Electrochemicalperformance1stdchcapacity:2404mAh/g1stchcapacity:1541mAh/g1stcoulombicefficiency:64.1%Reversiblecapacity1:1504mAh/gCapacityretention:67%after200cyclesRecipe:PorousSi-C:CB:binder(PAA)=6:2:2;Electrolyte:1MLiPF6inEC-DMC-EMC(1:1:1vol%)with2wt%VC2;loading:0.61

mg/cm2.Capacityisonlybasedonactivematerial.Currentdensity:0.1A/gfor1-2cycle,then0.5A/g;Voltage:0.05–2.0Vvs.LiCharge-DischargecurvesCyclingRatecapabilityIncreasecurrentdensityfrom0.1to2Ag-1,thespecificcapacityofSi/Ccompositeisstillabove500mAhg-1,whenthecurrentdensitychangesbackto0.1Ag-1,morethan92%ofthecapacityatthefirsttencyclesisrecoverable.12/13/202238CurrentDensity(A/g)Dischargecapacity(mAh/g)Chargecapacity(mAh/g)Coulombicefficiency(%)0.192386293.40.562962699.51.046146099.72.03113111000.176675798.9ResultsandanalysisRatecapabilityIncreasecurrenNyquistplotofSi-Ccompositeattheendofdischargeafterdifferentcyclesin1bold,1eElectrochemicalimpedancespectra(EIS)measurementina5.0mVACvoltagesignalinthe105-0.02Hzfrequencyrange.BeforeeachEIStest,theelectrodesweredischargedto0.01Vgalvanostaticallyandthenremainedatopen-circuitforatleast2htostabilizetheirpotential.Theconstancyofthecharacteristicfrequency(20Hz,from30-60cycles)suggeststhatthekineticsofthechargetransferreactiondoesnotvaryuponcycling.Evolutionoftheresistanceinmid-frequencyregion(inset)showsanincreaseinfirst5cyclesthenreduceandmaintainaround40Ohminlatercycles.Resultsandanalysis12/13/202239EIStest[1]D.Guyomard,J.Mater.Chem.,2011,21,6201.NyquistplotofSi-CcompositeSEIfilmwithcyclingSuperficialandcross-sectionalSEMimagesofourcompositeaftera),b)10cycles;c),d)20cycles;e),f)50cyclesandg),h)commercialSimaterialafter50cycles.a)b)d)c)h)g)f)e)PorousstructureofoursynthesizedcompositestillmaintainsaftercyclingandSEIfilmisonlyobservedattheexternalsurfaceofthesiliconparticlewithoutobviousincrassation.IncommercialSimeasurements,excessiveSEIfilmisfoundafter50cycles,whichisunabletobedistinguishedfromSinanoparticles.12/13/202240SEIfilmwithcyclingSuperficiMaterialsaftercycling[1]Y.Cui,NanoLett.10(2010)1409Si/Cafter50cyclesa)SEMandb)TEMimageofSi/Ccompositeattheendof50thcycle;

thecorrespondingelementalmappingofc)carbonandd)silicon.1mMofaceticacidwasusedtoremovetheSEIfilm[1].Porouscarbonstructureismaintained,nanosiliconparticlesaround10nmdoesnotshowaggregationandrupture.Resultsandanalysisa)b)c)d)C-KSi-K12/13/202241Materialsaftercycling[1]Y.SEIconfinementSchematic12/13/202242SEIfilmformsinsidetheporesduetothelowelectrochemicalpotentialoflithiuminsertioninfirstfewcycles.Whentheporesarefullfilled,SEIfilmisconfinedbythewallofcarbonsubstrate,whichpreventtheinternalsiliconparticlefrombeingexposedintheelectrolyte.ResultsSEIconfinementSchematic12/12/12/13/202243SchematicofsynthesisAdvantage:1.EasytosynthesisandregulateaccordingtocommercialCaCO3template2.Hollowstructurewithreservevolumecanaccommodatelargevolumechanges3.Interconnectednanosiliconmeansmoreactiveconductivecontact.NanoCaCO3SiliconlayerLegend:HollowsiliconPurificationbyHFacid(10wt%)5%SiH4+95%Ar400-500C,1h-2.5hSiCVDTemplateremovalbyHClacid(2wt%)12/12/202217Schematicofsynth12/13/202244ImagesandpatternsMorphologyResultsa)TEMimagesofnanoCaCO3template;b)SEMimagesofHSA-10(insetisatlowmagnification);TEMimagesofc)HSA-10,e)HSA-15,f)HSA-20;d)thecorrespondingSAEDpatternofHSA-10.Amorphoushollowsiliconmaterialwithdifferentshellthicknesswaspreparedabcdef12/12/202218Imagesandpattern12/13/202245ImagesandpatternsStructuralcharacterizationbcCharacteristicpeaksofcrystallinesilicon(PDF#65-1060)around28°,47°and56°areabsent,whichcorroboratethestatementofsiliconisamorphous.Thefirstmain3/2-1/2doublet(thespin-orbitsplittingis0.6eVandtheintensityratiois3:1),locatedat99.1-99.7eVcorrespondstoSi0(75%content).Thecomponentlocatedathigherbindingenergy(100.0eV)isassociatedwithSiOxformedatthesurfaceofHSAwithaproportionof25%.Resultsandanalysis12/12/202219Imagesandpattern12/13/202246ResultsandanalysisThenitrogenadsorption/desorptionisothermsofHSAsamplesshowasharpcapillarycondensationstepathighrelativepressures(P/P0=0.85-0.99),indicatingtheexistenceoflargepores.Correspondingporesizedistributesmainlyintherangeof20nmand100nm,whichisattributedtotheremovalofsite-occupyingnanoCaCO3.IsothermandPoresizedistributionPorousStructureSampleSpecificsurfacearea(m2g-1)Porevolume(ccg-1)HSA-1050.40.983HSA-1538.60.221HSA-2032.70.09112/12/202220Resultsandanalys12/13/202247CyclingperformanceCycleperformanceTestconditionsRecipe:HS:CB:binder(PAA)=6:2:2Electrolyte:1MLiPF6inEC-DMC-EMC(1:1:1vol%)with2wt%VC;Loading:0.4-0.6mgcm-2

Currentdensity:0.1A/gfor1-3cycle,then0.4A/g;Voltage:0.02–1.50Vvs.LiResultsHSA-10givesthehighestcapacityretention(91%)in100cyclesandcorrespondingreversiblecapacityis~980mAhg-1.Whenincreasetheshellthicknessofsilicon,reversiblecapacityincreases(980mAhg-1ofHSA-15and1133mAhg-1ofHSA-20after100cycles)butthecapacityretentiondecreasesobviously(76%ofHSA-15and73%ofHSA-20)Electrochemicalperformance12/12/202221CyclingperformancMaterialsaftercycling[1]Y.Cui,NanoLett.10(2010)1409HAS-10after50cyclesa)SEMimageofHSA-10after100cycles;b)SEMimageofHSA-10after100cycleswithoutSEIfilm;c),d)TEMimag