锂离子电池正极材料lifepo4与li2fesio4的合成与改性分析

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1、中南大学硕士学位论文ABSTRACTThedevelopmentofrechargeable1ithium．ionbatteriesandcathodematerials2urereviewedindetail．Withtheadvantagesofabundantrecource，non—toxici劬hi曲saf-e劬lowcost，LiFeP04andLi2FeSi04haVebeenconsideredasapromisingcathodematerialonlithium-ionbatteries．Synthesisofmaterials，mo

2、diflcationprocess，structurech2uracterization，electrochemicalbehaViorsofLiFeP04andLi2FeSi04hasbeeninvolvedinmisstudy．BasedonthedisadVantagesofunstablepropertiesofFeP04‘xH20、vhichistherawmaterialsofLiFeP04，thepureFeP04。坩20wasprep2uredby1iquidprecipitationmethod．Theeffectofreactants

3、’concentrationonthephysicalperformanceandelectrochemicalbehaviorofFeP04·她20precorsorandLiFeP04wasstudied．TheresultsshowedthatLiFeP04syntllesisedbyhomogeneousFeP04‘2H20precorsorhadthebestelec臼ochemicalpropertieswhen也econcentrationwas1．Om01·L～．Basedont11edisaClvantagesofpooriondif如

4、sionandlowelectronicconductivityofthepurephaseLi2FeSi04，theLi2FeSi04waspreparedbysol—geltechniqueusingcitricacidaSacomple)【ingagent．Comp撕sonresearchonperfomlanceoftwos锄pleswhichprep2uredbydif-feremwaysbyusingcitricacidornothavebeenstudied，theresultmes锄plebyusingcitricacidwithbett

5、erc巧stallin时，unifomlparticlesandexcellentelectrochemicalproperties．TheinitialdischargecapacityofLi2FeSi04synthesizedis135．4nlAh。g吐atC／l6rateandthecapacityfadingisonly15．7％aRer30cycles．Theef．fectofcomplexratioonthephysicalstructureandelectrochemicalpropeniesofLi2FeSi04wasresearche

6、d．TheresultsindicatedthattheelectrochemicalpropertiesofLi2FeSi04increasedthendecreasedwiththechangingofcomplexratioandmebests锄pleobtained、)l，：henmecomplexratiois1．O．Accordingtoprelimin州studiesbyourgroup，addingonlyal【indoforganiccarbonwouldimprovetheelectrochemicalpropertiesofLi2F

7、eSi04limited，therefOre，t11einfluenceofsurf-acemodiflcationbycombinedorgalliccarboncoatingont11epr叩eniesofLi2FeSi04／CwasIⅡ中南大学硕士学位论文ABSlRACTinvestigated．nwasfound廿1att11eLi2FeSi04／Cbyadding35％c矾cacid+5％91ucose+5％p”omelliticar血ydrideascarbonsourcehas也eoutstandingelec乜．ochemicalprop

8、erties．Mean、Ⅳhile，theef-fectofsymhesisco