A facile route to carbon-coated SnO2 nanoparticles combined with a new binder for enhanced cyclabili

A facile route to carbon-coated SnO2 nanoparticles combined with a new binder for enhanced

ElectrochimicaActa54 (2009) 7519–7524

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Electrochimica

Acta

journalhomepage:doc.guandang.net

a

Afacileroutetocarbon-coatedSnO2nanoparticlescombinedwithanewbinderforenhancedcyclabilityofLi-ionrechargeablebatteries

Shu-LeiChoua,b, ,Jia-ZhaoWanga,b,ChaoZhonga,b,M.M.Rahmana,b,Hua-KunLiua,b,Shi-XueDoua

ab

InstituteforSuperconductingandElectronicMaterials,UniversityofWollongong,NSW2522,AustraliaARCCenterofExcellenceforElectromaterialsScience,UniversityofWollongong,NSW2522,Australia

articleinfoabstract

Carbon-coatedSnO2nanoparticleswerepreparedbyanovelfacilerouteusingcommercialSnO2nanopar-ticlestreatedwithconcentratedsulfuricacidinthepresenceofsucroseatroomtemperatureandambientpressure.Thekeyfeaturesofthismethodarethesimpleprocedure,lowenergyconsumption,andinexpensiveandnon-toxicsourcematerials.As-preparedcore/shellnanoparticleswerecharacterizedbyX-raypowderdiffraction(XRD),thermogravimetricanalysis(TGA),scanningelectronmicroscopy(SEM),energy-dispersiveX-rayspectrometry(EDX),transmissionelectronmicroscopy(TEM),andhigh-resolutiontransmissionelectronmicroscopy(HRTEM).Theelectrochemicalmeasurementsshowedthatthecarbon-coatedSnO2nanoparticleswith10%carbonandusingcarboxymethylcellulose(CMC)asabinderdisplayedthebestelectrochemicalperformancewiththehighestspeci ccapacityof502mAhg 1after50cyclesatacurrentdensityof100mAg 1.Inaddition,owingtothewatersolvabilityofCMC,theusageofCMCasbindermakesthewholeelectrodefabricationprocesscheaperandmoreenvironmentalfriendly.

© 2009 Elsevier Ltd. All rights reserved.

Articlehistory:

Received14July2009Accepted2August2009

Available online 11 August 2009Keywords:SnO2

Carboncoating

Lithium-ionbatteryBinder

Nanoparticles

1.Introduction

Rechargeablelithium-ionbatteriesarecurrentlythetechnol-ogyofchoiceforportableelectronicdevices[1,2].Inordertomeettherequirementsoftherapidlyincreasingportableelectron-icsmarket,theperformanceofrechargeablelithium-ionbatteriesneedstobeimprovedwithhigherenergydensityandbetterratecapability.Currently,thecommercialanodematerialofchoiceisgraphite,whichhasarelativelylowtheoreticalcapacityaround370mAhg 1[3].Materialsbasedontinoxidehavebeenpro-posedaspromisingalternativeanodematerialsforrechargeablelithiumbatteriesowingtotheirhightheoreticalcapacity(SnO2:790mAhg 1)[4–9].Theseverevolumeexpansionandcontractionduringthealloying–dealloyingcycleswithLi+ionsisthemainhin-drancetothecommercialuseofSnO2[10].Inordertoalleviatethevolumechanges,twomainmethodshavebeeninvestigated,fabricatingSnO2intonanostructures[11–18]andadding/coatingwithbuffermaterials(suchascarbonorotherconductivemateri-als),insideoroutsidetheparticles[19–26].VarioustypesofSnO2nanostructures,suchasnanotubes[11–14],nanowires[15,16],andnanorods[17,18],havebeeninvestigatedandwerefoundto

Correspondingauthorat:InstituteforSuperconductingandElectronicMate-rials,UniversityofWollongong,North eldsAvenue,Wollongong,NSW2522,Australia.

E-mailaddress:sc478@uow.edu.au(S.-L.Chou).0013-4686/$–seefrontmatter© 2009 Elsevier Ltd. All rights reserved.doi:10.1016/j.electacta.2009.08.006

haveenhancedelectrochemicalperformance.Theyprovidemorereactionsites,shortLi+diffusionlengths,andconsiderablekineticenhancement.However,thehighcostforsynthesizingthenanos-tructuredmaterialsandtherelativelylowcapacityretentionstillneedtobeaddressedforfuturecommercialapplication.Ontheotherhand,surface-coated/compositeSnO2showedbetterelec-trochemicalperformancethanthebarematerial.Amongthebuffermaterials,carbonhastobeconsideredasthebestchoicebecauseofitscheap,light,andconductivenature.Todate,carboncoatedontooraddedintoSnO2hasbeenpreparedbyspraypyrolysis,polymercoatingandthencarbonization,andhydrothermal/solvothermalmethods[19–25].However,itisstillimportanttoexploreeco-nomicalsynthesistechniqueswithlowenergyconsumptionfortheformationofcarbon-coatedSnO2.

Recently,thechoiceofbinderhasbecomeaveryimportantissuein ndingasolutiontotheproblemofthelargecapac-ityfadeobservedforanodematerialsaftercycling[27–31].Buqaetal.reportedthatnano-Sielectrodecontaining1%sodiumcar-boxymethylcellulose(CMC)asbindershowsthesamecyclestabilityasanidenticalelectrodecontaining10%conventionalpolyvinylidene uoride(PVdF)binder[27].Lestriezetal.claimedthattheextendedconformationofCMCinsolutionfacilitatesanef cientnetworkingprocessbetweentheconductiveagentandtheSiparticles[28].Hochgattereretal.reportedthatthechemi-calbondingbetweenCMCbinderandSiparticlescontributestotheenhancedcapacityretentionofSi/Ccompositeelectrodes[29].Lietal.reportedthatFe2O3electrodesusingCMCbinderandtwoother