磷酸铁前驱体形貌对磷酸铁锂电化学性能的影响

4212人工晶体学报Vol．42No．12201312JOUＲNALOFSYNTHETICCＲYSTALSDecember2013何岗，权晓洁，张靖，洪建和，何明中430074LiFePO4/C。。XＲDSEM、。180℃。。。TM911A1000-985X201312-2548-082013-09-042013-11-06KF201305201320130105010101421959-。[e-mail]ronPhosphatePrecursorsontheElectrochemicalPerformanceofLithiumIronPhosphateHEGangQUANXiao-jieZHANGJingHONGJian-heHEMing-zhongFacultyofMaterialScienceandChemistryChinaUniversityofGeosciencesWuhan430074ChinaＲeceived4September2013accepted6November2013AbstractTheironphosphateprecursorswerepreparedbyprecipitationmethodandhydrothermalsynthesismethodandthenLiFePO4/Cwassynthesizedbycarbothermalreductionmethod．Theeffectofmorphologyofironphosphateontheelectrochemicalperformanceoflithiumironphosphatewasinvestigated．ThecharacterizationonthestructureandmorphologywascarriedoutbyXＲDandSEM．TheresultsindicatethatwiththelongertimeofthehydrothermalreactionthecrystallinityoftheironphosphatewasbettertheparticlesofironphosphatebecamesphericalandtheLiFePO4/Chadbettertheelectrochemicalperformance．Howeverwhenthesynthesistemperaturereached180℃theparticlesbecameellipsoidalandtheLiFePO4/Chadahighdischargecapacityonthecontrary．AlloftheLithiumironphosphatepreparedbytheironphosphateprecursorswerehomogeneousphasewitholivinestructurebutthedifferentmorphologyresultedtodifferentelectrochemicalperformanceoftheLiFePO4/C．ThemorphologyofironphosphateprecursoreffectedtheelectrochemicalpropertyoftheLiFePO4/Cbutit＇snotthekeypointfactor．Keywordslithiumironphosphateironphosphateprecipitationmethodhydrothermalmethod1Goodenough12122549。LiFePO4、、、、、3。4-6、7-13、141516-22、-2324、25。。LiFePO4FePO4LiFePO4Pnmb6．8%1/。、、。22．170℃pH1．515min、、80℃FePO4·xH2O。70℃pH1．515min、、80℃。70℃pH1．515min120℃、150℃180℃6h、、80℃。150℃2h、6h10h。70℃pH1．515min120℃、150℃180℃6h、、80℃。2．2/FePO4=12at%400/FePO4=18wt%300℃6h600℃4hLiFePO4/C。2．385∶10∶5、PTFEN-120℃12h。1mol/LLiPF6/EC-DMC-EMC1∶1∶1CＲ2016。2．4D8-FocusXBＲUKEＲCuKαNi40mA40kV5°～70°0．01°12°/minSU8010。CT2001A0．2C-1C-2C-5C2．5～4．2Vvs．Li/Li+25℃。33．1TG-DSC-FePO4·2H2Ox=2。2550423．21a650℃12hXＲD。XＲD。XＲDPDF#29-0715。1bLiFePO4/CXＲD。PDF#40-1499Pnmb。1abXＲDFig．1XＲDpatternsofferricphosphateaandLiFePO4/CbsynthesizedbyprecipitationmethodusingironIIsource2abXＲDFig．2XＲDpatternsofferricphosphateaandaftersinteredbsynthesizedatdifferenttemperaturebyhydrothermalmethodusingironIIsource2a120℃、150℃、180℃XＲD。。PbcaPDF#02-0250FePO4·2H2OPbcaPDF#03-0452FePO4·2H2OFe2NH4OHPO42·2H2O、FeH2P3O10·H2O、FeH2PO43。2b650℃12hXＲD。PDF#29-0715。3120℃、150℃、180℃XＲD。120℃150℃150℃150℃120℃。PcabPDF33-0667FePO4·2H2OP21/nPDF33-0666FePO4·2H2O。。122551180℃120℃150℃P21/nPDF#33-0666FePO4·2H2OPDF#45-1436Fe5PO44OH3·2H2O。4150℃6hXＲD。PDF#40-1499Pnmb。3XＲDFig．3XＲDpatternsofferricphosphatesynthesizedatdifferenttemperaturebyhydrothermalmethodusingironIIIsource4XＲDFig．4XＲDpatternofLiFePO4/CsynthesizedbyhydrothermalmethodusingironIIsource3．35SEM。。。6a、6b150℃6hSEM。6ac。6b6d。5acbdSEMFig．5SEMimagesofferricphosphatesynthesizedbyferroussulfateacandferricnitratebdbyprecipitationmethod7120℃、150℃180℃SEM。120℃5μm。150℃5μm。180℃。150℃。2552426acbdSEMFig．6SEMimagesofferricphosphatesynthesizedbyferroussulfateacandferricnitratebdbyhydrothermalmethod7120℃ad、150℃be180℃cfSEMFig．7SEMimagesofferricphosphatesynthesizedbyferroussulfateat120℃ad150℃beand180℃cfbyhydrothermalmethod82had、6hbe10hcfSEMFig．8SEMimagesofferricphosphatesynthesizedbyferroussulfateat2had6hbeand10hcfbyhydrothermalmethod1225538a、8b、8c150℃2h、6h10hSEM。8a5μm。8b5μm。8c10μm。。3．49a。0．2C141mAh/g。。9b150℃6h。。。9abFig．9DischargecyclecurvesofLiFePO4/Csynthesizedbyprecipitationmethodaandhydrothermalmethodb10Fig．10DischargecyclecurvesofLiFePO4/Csynthesizedbyferroussulfateatdifferenttemperatureaandtimebbyhydrothermalmethod10a120℃、150℃180℃。。120℃150℃180℃6h。10b150℃25544211150℃6h、10h180℃6h、10hFig．11DischargecyclecurvesofLiFePO4/Csynthesizedbyferroussulfateat150℃6h10h180℃6h10hbyhydrothermalmethod2h、6h、10h。10h。150℃2h6h10h6h10h10h。11150℃180℃6h10h。180℃、6h150℃、10h2C5C。。180℃。4。。1pH=1．570℃23180℃。1PadhiAKNanjundaswamyKSGoodenoughJB．Phospho-olivinesasPositive-electrodeMaterialsforＲechargeableLithiumBatteriesJ．JournalofTheElectrochemicalSociety199714441188-1194．2YamadaAChungSCHinokumaK．OptimizedLiFePO4forLithiumBatteryCathodesJ．JournalofTheElectrochemicalSociety20011483A224-229．3．M．200712．4WangKCaiＲYuanTetal．ProcessinvestigationElectrochemicalCharacterizationandOptimizationofLiFePO4/CCompositefromMechanicalActivationusingSucroseasCarbonSourceJ．ElectrochimicaActa200954102861-2868．5MaZPShaoGJWangGLetal．ElectrochemicalPerformanceofMo-dopedLiFePO4/CCompositesPreparedbyTwo-stepSolid-stateＲeactionJ．Ionics2013193437-443．6LeeJKumarPLeeGetal．ElectrochemicalPerformanceofSurfactant-processedLiFePO4asaCathodeMaterialforLithium-ionＲechargeableBatteriesJ．Ionics2013192371-378．7FrangerSBourbonCCrasFL．OptimizedLithiumIronPhosphateforHigh-rateElectrochemicalApplicationsJ．JournalofTheElectrochemicalSociety20041517A1024-1027．8ZhaoBJiangYZhangHJetal．MorphologyandElectricalPropertiesofCarbonCoatedLiFePO4CathodeMaterialsJ．JournalofPowerSources20091891462-466．1225559BarkerJSaidiMYSwoyerJL．LithiumIron