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1、北京工業(yè)大學(xué)博士學(xué)位論文鐵基磷酸鹽正極材料的研究姓名：王忠麗申請學(xué)位級別：博士專業(yè)：環(huán)境科學(xué)指導(dǎo)教師：夏定國20090501LiC002(10-1010。12cm2／s)相當(dāng)。該材料具有良好的電化學(xué)性能，在1C(170mAh／g)下，放電比容量可高達160mAh／g，在4C(680mA／g)下循環(huán)50次放電比容量保持在120mAh／g。關(guān)鍵詞：LiFeP04；XAS；第一性原理計算；摻雜占位；固溶放電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
