Synthesis and electrochemical performances of spherical LiFePO4 cathode materials for Li-ion batteries

(整期优先)网络出版时间:2006-04-27
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SphericalLiFePO4andLiFePO4/Ccompositepowdersforlithiumionbatteriesweresynthesizedbyanovelprocessingrouteofco-precipitationandsubsequentcalcinationsinanitrogenandhydrogenatmosphere.TheprecursorsofLiFePO4,LiFePO4/CcompositeandtheresultantproductswerecharacterizedbyX-raydiffraction(XRD),scanningelectronmicroscope(SEM),andtheelectrochemicalperformanceswereinvestigatedbygalvanostaticchargeanddischargetests.TheprecursorscomposedofamorphousFe3(PO4)2·xH2OandcrystallineLi3PO4obtainedintheco-precipitationprocessinghaveasphere-likemorphology.ThesphericalLiFePO4derivedfromthecalcinationsoftheprecursorat700℃for10hinareductionatmosphereshowsadischargecapacityof119mAh·g-1attheC/10rate,whiletheLiFePO4/Ccompositewith10wt.%carbonadditionexhibitsadischargecapacityof140mAh·g-1.TheelectrochemicalperformancesindicatethattheLiFePO4/CcompositehasahigherspecificcapacityandamorestablecyclingperformancethanthebareolivineLiFePO4duetothecarbonadditionenhancingtheelectronicconductivity.