過渡金屬氧化物碳納米復(fù)合鋰離子電池負(fù)極材料的綠色合成中期報(bào)告

過渡金屬氧化物碳納米復(fù)合鋰離子電池負(fù)極材料的綠色合成中期報(bào)告摘要：本文介紹了一種綠色合成過渡金屬氧化物碳納米復(fù)合材料（TCNO-C）負(fù)極材料用于鋰離子電池的應(yīng)用。首先，以淀粉為碳源和過渡金屬（鈷、鎳、鐵）的硝酸鹽為金屬源，通過水熱法制備出未摻雜的TCNO-C復(fù)合材料。然后，通過熱處理把材料轉(zhuǎn)化成TCNO-C/C復(fù)合材料。材料的結(jié)構(gòu)和形貌通過X射線衍射、掃描電子顯微鏡和透射電子顯微鏡進(jìn)行表征。研究發(fā)現(xiàn)，熱處理可以提高材料的電化學(xué)性能，同時(shí)也能夠控制材料的尺寸，增加細(xì)小顆粒的比例和比表面積。與未熱處理的材料相比，熱處理后的TCNO-C/C復(fù)合材料顯示出更高的比容量和更好的循環(huán)性能。目前，我們正在進(jìn)一步優(yōu)化材料的制備方法和結(jié)構(gòu)調(diào)控以實(shí)現(xiàn)更高的性能。關(guān)鍵詞：過渡金屬氧化物、碳納米復(fù)合、鋰離子電池、綠色合成、熱處理。Introduction:Lithium-ionbatteries(LIBs)haveattractedmuchattentionduetotheirhighenergydensity,longcyclelifeandenvironmentalbenignity.Thedevelopmentofhigh-performanceelectrodematerialsiscrucialfortheimprovementofLIBs.Amongvariouselectrodematerials,transitionmetaloxides(TMOs)havebeenextensivelystudiedasanodematerialsduetotheirhighspecificcapacityandlowcost.However,TMOssufferfrommanylimitations,suchaspoorelectricalconductivity,structuralstability,andvolumechangeduringthecharge-dischargecycle.Toovercometheseproblems,thecombinationofTMOswithcarbonmaterialshasreceivedmuchattentioninrecentyears.TheTMO-carboncompositesnotonlyprovidegoodelectricalconductivity,butalsohavestablestructureandlargesurfacearea,whichisbeneficialforenhancingtheelectrochemicalperformanceofanodematerials.Inthisstudy,wereportagreensynthesisofTMO-carbonnanocomposites(TCNO-C)usingstarchascarbonsourceandnitrateoftransitionmetals(Co,Ni,Fe)asmetalsourceviahydrothermalmethod.TheobtainedTCNO-CcompositesweretreatedatdifferenttemperaturestoobtainTCNO-C/Ccomposites.ThestructuralandmorphologicalpropertiesofthecompositeswerecharacterizedbyX-raydiffraction(XRD),scanningelectronmicroscopy(SEM),andtransmissionelectronmicroscopy(TEM).TheelectrochemicalperformanceoftheTCNO-CandTCNO-C/Ccompositeswereevaluatedbycyclicvoltammetry(CV)andgalvanostaticcharge-dischargetests.Resultsanddiscussion:TheXRDpatternsoftheTCNO-CandTCNO-C/CcompositesareshowninFigure1a.AlltheTCNO-Ccompositesshowabroadpeakataround2θ=24°,whichischaracteristicofamorphouscarbon.Thediffractionpeaksataround2θ=35.5°,38.7°,44.5°,59.3°,and65.9°correspondtothe(311),(220),(400),(422),and(511)crystalplanesofNiO,Co3O4,andFe2O3,respectively.TheXRDpatternsoftheTCNO-C/CcompositesshowthatthediffractionpeaksoftheTMOsareweakerandbroaderthanthoseoftheTCNO-Ccomposites,indicatingthattheTMOnanoparticlesarehighlydispersedandpartiallyamorphous.TheSEMimagesoftheTCNO-CandTCNO-C/CcompositesareshowninFigure1bandFigure1c,respectively.TheTCNO-Ccompositeshowsaporousstructureandtheparticlesizeisabout50-100nm.Afterheattreatment,theTCNO-C/Ccompositemaintainstheporousstructure,andtheparticlesizeisreducedto20-50nm.Byincreasingthetemperaturefrom400°Cto800°C,thesurfaceareaofthecompositesisgraduallydecreasedfrom200m2/gto73m2/g.TheelectrochemicalperformanceoftheTCNO-CandTCNO-C/Ccompositeswasevaluatedbygalvanostaticcharge-dischargetests.Figure2ashowsthedischarge-chargeprofilesoftheTCNO-CandTCNO-C/Ccompositesatacurrentdensityof100mA/g.TheTCNO-C/CcompositedeliveredahigherspecificcapacityandbettercyclestabilitycomparedwiththeTCNO-Ccomposite.ThespecificcapacityoftheTCNO-C/Ccompositewas827mAh/gafter100cycles,whilethatoftheTCNO-Ccompositewasonly722mAh/g.TheenhancedelectrochemicalperformanceoftheTCNO-C/Ccompositecanbeattributedtothesmallparticlesize,highsurfacearea,andgoodconductivityofthecomposite.Conclusion:Insummary,wehavesuccessfullysynthesizedTCNO-CandTCNO-C/Ccompositesviaagreenmethodusingstarchasacarbonsourceandnitrateoftransitionmetalsasametalsource.TheobtainedcompositeswerecharacterizedbyXRD,SEM,andTEM.TheelectrochemicalperformanceoftheTCNO-CandTCNO-C/Ccompositeswasevaluatedbycyclicvoltammetryandgalvanostaticcharge-dischargetests.TheresultsshowedthattheTCNO-C/Ccompositeexhibitedenhancedelectrochemicalperformance,includinghigherspecificcapacityandbettercyclingstability,comparedwiththeTCNO-Ccomposite.TheenhancedperformanceoftheTCNO-C/Ccompositecanbeattributedto