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1、A158JournalofTheElectrochemicalSociety,1552A158-A16320080013-4651/2007/1552/A158/6/$23.00©TheElectrochemicalSocietySiElectrodesforLi-IonBatteries—ANewWaytoLookatanOldProblema,zaabaS.D.Beattie,D.Larcher,M.Morcrette,B.Simon,andJ.-M.TarasconaLaboratoired
2、eRéactivitéetChimiedesSolides,UniversitédePicardie-JulesVerne,UMRCNRS6007,80039,Amiens,FrancebSaft-111,33074Bordeaux,FranceHigh-capacitySi-basedelectrodescouldreplacecarbon-basedelectrodesinthenextgenerationofLi-ionbatteries.AlthoughSi-basedelectrodeshavela
3、rgegravimetriccapacities,theytypicallysufferfrompoorcyclability.Onereasonforthepoorcycla-bilityislargevolumeexpansionassociatedwith3.75molofLireactingwith1molofSi.Atheoreticalapproachtodesignelectrodesthatcanaccommodatethislargevolumeexpansionisdiscussed.It
4、isshownthatexperimentalresultsagreewellwiththetheoreticalapproach.WeshowthatSi-basedelectrodeswitharelativelylowSicontent33wt%andhighbindercontent3356wt%cycleatlargecapacities660mAh/gforhundredsofcycles.Nospecialelectrodeprocessingorcyclingprocedure
5、sarerequiredtoachievehighcapacitieswithgoodcyclability.©2007TheElectrochemicalSociety.DOI:10.1149/1.2817828Allrightsreserved.ManuscriptsubmittedJuly25,2007;revisedmanuscriptreceivedOctober17,2007.AvailableelectronicallyDecember17,2007.Si-basednegative-ele
6、ctrodematerialscouldsignificantlyincreaseComparedtoSi,theLi22Si5phasecorrespondstoavolumeincrease13,14theenergydensityofcommerciallithium-ionbatteries.Comparedtoof310%.TheLi15Si4phasecorrespondstoanexpansionofconventionalLi-ionbatterymaterials,Sihasthelarges
7、ttheoretical2270%;thisvalueisusedinlatercalculations.InRef.14percent1gravimetriccapacity15Li+4Si→Li15Si4;3579mAh/g,arela-volumeexpansion%ViscalculatedasfollowstivelylowaveragevoltagetheaveragedelithiationvoltageofSiis0.4V,andalargevolumetriccapacit
8、y2200mAh/cm3.Unfor-%V=Vf−Vi100%tunately,Si-basedelectrodestypicallysufferfrompoorcapacityre-Vitention.Forexample,consideranelectrodemadefrom80%Si−325whereVfisthefinalvolumeandViistheinitialvolume.Us
