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1、第19卷第6期電化學(xué)VOl_19No．62013年12月JOURNALOFELECTROCHEMISTRYDec．20l3DOI：10．13208~．electrochem．130356ArticalID：1006—3471(2013)06—0565—06EffectofVanadiumSubstitutiononStructureofLi2FeSiOdCCompositesYANGHong，ZHANGYing，CHENGXuanr1．DepartmentofMaterialsScience&Engineering,Collegeo
2、fMaterials；2．FujianKeyLaboratoryofAdvancedMaterials，XiamenUniversity,Xiamen361005，F(xiàn)ujian,China)Abstract：Thecarboncoatedlithiumironsilicate(Li2FeSiOdC)compositeswerepreparedusinglessexpansiveironstartingmaterialofsolubleferricnitratethroughsol-gelprocessandsolidstaterea
3、ction．Thetheoreticallycalculatedamountsof5％，10％，15％，20％，25％，30％，and50％ofvanadium(V)wereintroducedusingNH4VO3toobtainV—substitutedLi2FeSiOdCcomposites．ItwasfoundthatthepureLi2FeSiOJCcompositeexhibitedagoodcrystallinitywith1andnearlynoimpuritiesbeingdetected，whiletheV—su
4、bstitutedLi2FeSiOdCcompositesshowedmajorimpuritiesofLi2Si03andV3O4／Fe304．Thedischargecapacitiesof160．9mAh·g-and130．8mAh·gatC／16wereobtainedforthepureand5％V-substitutedLi2FeSiO4／Ccomposites，respectively．Thedegreeofgraphitizationinamorphouscarbonwasenhancedandthequantiti
5、esofcarboncoatedwereloweredwiththeincreaseofV-substitutedamounts．Theelectrochemicalperformanceof5％V—substitutedLi2FeSiO4／CcompositewasnotimprovedduetothepresencesofimpuritieswhichweredirectlylinkedtotheamountsofVsubstitution．Keywords：lithiumironsilicates；vanadiumsubsti
6、tution；cathodematerials；lithiumionbakeryCLCNumber：0646DocumentCode：AThepolyanion—typecathodematerialofLi2FeSiO4alcationsincludingM，CuandZn2~舊，Un2+7-8]，isconsideredasoneofthemostpromisingcathodeNi[9]．orCr2+t0]inLi2FeSiO4hasbeenextensivelyin—materialsforlithiumionbaRerie
7、sbecauseofitsex—vestigated．However,vanadium(V)modificationsarecellentstructuralstability，goodreliabilityandhi1essstudied．DiversifiedvalencestatesofVanddifi—performancewithanominalcapacityof330mAh·gcultiesinidentificationsofVpresentedafterdop—upontwolithiumionsbeingextr
8、acted．However，lowing／substitutionleadtocomplexitiesandvarietiesofintrinsicelectricalconductivityandpoordischargeVexis
