硅负极材料的相关应用介绍.ppt

寿命寿命硅负采材料Siliconanodewithlifecyclelife Prof XinpingQiuDepartmentofChemistry TsinghuaUniversityBeijing 100084 China 3 29 2020 1 Si 4200mAh g Multielectronreactionmaterials 3 29 2020 2 J R Dahn Electrochem Solid StateLett 2001 4 A137 J R Dahn J Electrochem Soc 2003 150 A1457 Colossalvolumechange Changein a length andwidthx b height and c volumeofthea Sitowercomparedto d voltagevs AFMscannumber SchematicdiagramoftheinsituAFMapparatus OpticalmicrographofaLi alloyfilmafterexpansion 3 29 2020 3 Y 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 Strategiesforsiliconanodes 3 29 2020 4 Particlepulverization Astrongsizedependenceoffractureinsiliconmaterialwasdiscoveredthatthereexistsacriticalparticlesizeof 150nmbelowwhichcrackingdidnotoccur 2 Sizeeffect 1 HZhang NanoLetters2012 12 2778 2 XHLiu ACSNano 2012 2 1522 1531 Currentcollector Binder Array StabilityinSi basedmaterial 1 3 29 2020 5 TheexposedactivesurfaceduetothevolumechangecausecontinualformationofSEIfilmsandlowcoulombicefficiency CE Researchroutes ReducetheparticlesizetoaccommodateSEIfilmDesignporousorhollowstructuretobufferthevolumeexpansionCompositewithCorMetal Cu toincreaseelectronicconductivityandmodifytheinterfacebetweenSiandelectrolyte InvestigatenewbinderandelectrolyteadditivessystemforSi basedanodematerials StabilityofSEIfilm 3 29 2020 6 PorousSi Ccomposite SynthesisProcess 3 29 2020 7 Morphology in1bold 1ePorousstructureofcarbonsubstratecanbeobservedfromTEMimagesAfterCVD siliconparticlesadheretotheframeworkandporousstructurewasmaintained Particlesizeofsiliconis 10nmandhomogeneouslydispersed ThedepositedsiliconinPorousSi Cisamorphous asindicatedbytheabsenceofcrystallitesandbroaddiffuseringsintheSAEDpatterns Incontrast whencompositeisheatedto700 Cfor0 5h alatticefringecorrespondingtod111 0 31nmforsiliconisseeninPorousSi C 700 Resultsandanalysis SEMandTEMimages 3 29 2020 8 in1bold 1eObviouscharacteristicpeakofcrystalsiliconafterheattreatmentat700 Cfor0 5hThreeobviousdiffractionpeaksaround28 47 and56 arefoundafterheattreatment whichcorrespondverywelltothe 111 220 and 311 peaksofsiliconwithoutanyimpuritypeaks Thepeakat520cm 1 indicativeofcrystallinesilicon isnotdetectedaftersiliconCVD Thebandscenteredaround155 474cm 1andtheweakshoulderat400cm 1aretypicalfeaturesofamorphoussiliconvibrationmodes 1 Resultsandanalysis Structuralcharacterization 1 D Aurbach J Phys Chem C 2007 111 11437 XRDpatternsandRamanspectra 3 29 2020 9 N2sorptionisotherms Poresizedistribution BothporouscarbonandporousSi CshowtypeIVisotherm whichistypicalcharacteristicofmesoporousstructureObviousdecreaseofspecificsurfacearea SSA andporevolumeafterSiCVD Porouscarbon 650m2 g 1 32cc g PorousSi C 150m2 g 0 39cc g Poreswithdiameterof 3nmgeneratedbydecompositionofsucrosePoreswithdiameterof10 40nmduetotheremovalofCaCO3template whichwerereducedafterSiCVD PorousStructure 3 29 2020 10 Charge Dischargecurves Cyclingperformance 1 2ndchargecapacity 2 VC vinylenecarbonate Electrochemicalperformance 1stdchcapacity 2404mAh g1stchcapacity 1541mAh g1stcoulombicefficiency 64 1 Reversiblecapacity1 1504mAh gCapacityretention 67 after200cycles Recipe 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 Li 3 29 2020 11 Ratecapability Increasecurrentdensityfrom0 1to2Ag 1 thespecificcapacityofSi Ccompositeisstillabove500mAhg 1 whenthecurrentdensitychangesbackto0 1Ag 1 morethan92 ofthecapacityatthefirsttencyclesisrecoverable Resultsandanalysis 3 29 2020 12 NyquistplotofSi Ccompositeattheendofdischargeafterdifferentcycles in1bold 1eElectrochemicalimpedancespectra EIS measurementina5 0mVACvoltagesignalinthe105 0 02Hzfrequencyrange BeforeeachEIStest theelectrodesweredischargedto0 01Vgalvanostaticallyandthenremainedatopen circuitforatleast2htostabilizetheirpotential Theconstancyofthecharacteristicfrequency 20Hz from30 60cycles suggeststhatthekineticsofthechargetransferreactiondoesnotvaryuponcycling Evolutionoftheresistanceinmid frequencyregion inset showsanincreaseinfirst5cyclesthenreduceandmaintainaround40Ohminlatercycles Resultsandanalysis EIStest 1 D Guyomard J Mater Chem 2011 21 6201 3 29 2020 13 SEIfilmwithcycling Superficialandcross sectionalSEMimagesofourcompositeaftera b 10cycles c d 20cycles e f 50cyclesandg h commercialSimaterialafter50cycles PorousstructureofoursynthesizedcompositestillmaintainsaftercyclingandSEIfilmisonlyobservedattheexternalsurfaceofthesiliconparticlewithoutobviousincrassation IncommercialSimeasurements excessiveSEIfilmisfoundafter50cycles whichisunabletobedistinguishedfromSinanoparticles 3 29 2020 14 Materialsaftercycling 1 Y Cui NanoLett 10 2010 1409 Si Cafter50cycles a SEMandb TEMimageofSi Ccompositeattheendof50thcycle thecorrespondingelementalmappingofc carbonandd silicon 1mMofaceticacidwasusedtoremovetheSEIfilm 1 Porouscarbonstructureismaintained nanosiliconparticlesaround10nmdoesnotshowaggregationandrupture Resultsandanalysis a b c d C K Si K 3 29 2020 15 SEIconfinement Schematic SEIfilmformsinsidetheporesduetothelowelectrochemicalpotentialoflithiuminsertioninfirstfewcycles Whentheporesarefullfilled SEIfilmisconfinedbythewallofcarbonsubstrate whichpreventtheinternalsiliconparticlefrombeingexposedintheelectrolyte Results 3 29 2020 16 Schematicofsynthesis Advantage 1 EasytosynthesisandregulateaccordingtocommercialCaCO3template2 Hollowstructurewithreservevolumecanaccommodatelargevolumechanges3 Interconnectednanosiliconmeansmoreactiveconductivecontact Hollowsilicon 3 29 2020 17 Imagesandpatterns Morphology Results a TEMimagesofnanoCaCO3template b SEMimagesofHSA 10 insetisatlowmagnification TEMimagesofc HSA 10 e HSA 15 f HSA 20 d thecorrespondingSAEDpatternofHSA 10 Amorphoushollowsiliconmaterialwithdifferentshellthicknesswasprepared 3 29 2020 18 Imagesandpatterns Structuralcharacterization b c Characteristicpeaksofcrystallinesilicon 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 Resultsandanalysis 3 29 2020 19 Resultsandanalysis Thenitrogenadsorption desorptionisothermsofHSAsamplesshowasharpcapillarycondensationstepathighrelativepressures P P0 0 85 0 99 indicatingtheexistenceoflargepores Correspondingporesizedistributesmainlyintherangeof20nmand100nm whichisattributedtotheremovalofsite occupyingnanoCaCO3 IsothermandPoresizedistribution PorousStructure 3 29 2020 20 Cyclingperformance Cycleperformance TestconditionsRecipe HS CB binder PAA 6 2 2Electrolyte 1MLiPF6inEC DMC EMC 1 1 1vol with2wt VC Loading 0 4 0 6mgcm 2Currentdensity 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 Electrochemicalperformance 3 29 2020 21 Materialsaftercycling 1 Y Cui NanoLett 10 2010 1409 HAS 10after50cycles a SEMimageofHSA 10after100cycles b SEMimageofHSA 10after100cycleswithoutSEIfilm c d TEMimageofHSA 10after100cycleswithoutSEIfilmatdifferentmagnification Aggregatedsecondaryparticles Fig c and 10nmsiliconshellstructure Fig b d weremaintainedwithoutfractureofthehollowspheres Resultsandanalysis a b c d 3 29 2020 22 EIStest Stableinterfaceandsmallerresistance NyquistplotofSi Ccompositeattheendofdischargeafterdifferentcycles in1bold 1eElectrochemicalimpedancespectra EIS measurementina5 0mVACvoltagesignalinthe105 0 02Hzfrequencyrange BeforeeachEIStest theelectrodesweredischargedto0 01Vgalvanostaticallyandthenremainedatopen circuitforatleast2htostabilizetheirpotential Evolutionoftheresistanceinmid frequencyregionmaintains 20OhmduringcyclingwhichislowerthanSi CcompositeandnanoSimaterial Resultsandanalysis 3 29 2020 23 DSCTest StableSEIstructureofsiliconfoam DSCheatingcurves in1bold 1eCurrentdensityaround0 1mA gwasappliedtolithiatetheSiactivematerial Afterthevoltagereached1mV thecellswereremainedatopen circuitfor2hthencarefullyopenedinaglovebox TheelectrodewassoakedinDMCandthendriedundervacuumovernight MeasurementswereconductedwithaDSC1 METTLERTOLEDO atatemperaturerampof2 Cmin 1 30 300 C usinghermetichigh pressureDSCpans TheDSCsignalat86 100 Cisvisibleforallofthecurves Byanalogywithlithiatedgraphite whichthermalstabili