铁基磷酸盐正极材料的研究

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1、北京工业大学博士学位论文铁基磷酸盐正极材料的研究姓名：王忠丽申请学位级别：博士专业：环境科学指导教师：夏定国20090501LiC002(10-1010。12cm2／s)相当。该材料具有良好的电化学性能，在1C(170mAh／g)下，放电比容量可高达160mAh／g，在4C(680mA／g)下循环50次放电比容量保持在120mAh／g。关键词：LiFeP04；XAS；第一性原理计算；掺杂占位；固溶放电AbstractLithiumironphosphateisfocusedintheworldwilda

2、sapromisingcathodematerialforthepowerbatteriesintermsofitsexcellentstructuraIstability，lOWcost，andenvironmentalbenignityandsafety．ComparedwithLiC002andLiMn204，LiFeP04islowconductivityandlowtapdensity，whicharefundamentallimitationsforthismaterialtobeused．

3、Researchersintheworld．widehavemadeeffortsonthisissue．Toimproveitselectronicconductivity，twomainmeanswereexplored：oneisthesynthesisofLiFeP04withcarboncoating；theotheristhemodificationbydopingcationsintoLiFeP04．ThepresenceofcarboninLiFeP04decreasestheenerg

4、ydensity，butthemodificationbydopingcationsdoesn’tinducethisproblem．However，itisstillanopenquestionastowherethedopedcationsinLiFeP04goandnoclearevidenceexistsonLiandFesites．Toaddressthisissueinthiswork，sdveralworkshavebeendone，includingthesynthesisofcatio

5、n—dopedLiFeP04bysolid—statereactionorhydrothermalmethod，theinvestigationofdopingcationsoccupanciesandcharge／dischargemechanismofLiFeP04andtheexplorationofironhydroxyl—phosphates，anewcathodematerialforlithiumionbatteries．Theres'ultswegotlistinthefollowing

6、．Spherical—likeLiFeP04wassynthesizedfirstlybyhydrothermalmethodusingPhenanthrolineascomplexing—agenttoavoidtheFe(II)ionsfromoxidationandcontrolthegrowthofthecrystal．Thesamplepossessesuniformspherical-likeparticleswithaveragesizeofO．5pm．Testshowedthatther

7、eversiblecapacityofspherical．1ikeLiFeP04wasabout140mAh／gatO．1Candthecapacityfadingwasneglectableafter20cycles．ThedopingcationsoccupanciesoftheMo-dopedLiFeP04systemwereinvestigatedbyXAS．DatasupportaconcurrentreplacementofMoionsatFeandLisites．Theelectronic

8、structuresofMo．dopedLiFeP04werestudiedbyabinitiocalculationsusingVASEWithrespecttothedensityofstates(DOS)oftheLiFeP04，inwhichnoelectronicstateswereattheFermilevel，theModopingispredictedlargelyimpactingtheconductivity．Thete