阴阳离子复合掺杂锰酸锂正极材料的合成及其结构与性能研究

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1、桂林工学院硕士学位论文阴阳离子复合掺杂锰酸锂正极材料的合成及其结构与性能研究姓名：易凌英申请学位级别：硕士专业：应用化学指导教师：刘长久20070401桂林工学院硕士学位论文AbstractThespinelLiMn204asthecathodematerialforlithiumionbattery,atthepresenttime，theapplicationanddevelopmentwasrestrictedbecauseofMnsolubilityandJabn-Tellerdistor

2、tioncausingstructuralinstability．Becauseitexhibitsabundantresourceadvantage，lowcost，acceptableenvironmentcharacteristics．Accordingly,spinelLiMn204wasconsideredaSoneofthemostprospectiveandpreponderantcathodematerialforlithiumionbatteryandregardedbyrese

3、archers．Inrecentyears，spinelLiMn204hasbecomethefocusofresearchanddevelopmentallovertheworld．F—doping、F—Cu—doping、F-Cr-doping、F—Cu-Cr-dopinglithiummanganeseoxidesweresynthesizedbysol—gelmethod，theirstructures，electrochemicalpropertiesandactionmechanism

4、werediscussed。TheresultsshowedthatF·dopingfithiummanganeseoxideswereidentifedasasinglephaseofcubicspinel，andtheirinitialcapacitywereelevatedcomparedwithLiMn204，especiallyhadbettercyclabilityatelevatedtemperature．Despiteoftheelevatedinitialcapacity,the

5、singleFsubstitutiondeterioratedthecyclabilitywithF—dopingincreasing．ThesampleLiMn203，9F0lhadgoodproperties．Itsinitialdischargecapacitycarlbereached122．6mAh’g-1，95．5％oftheinitialdischargeeapacityWasreservedafter20cycles．Theanion-cationdopingLiCuxMn2_x0

6、39F01，LiCrxMn2．x039F0．1，LiCuxCryMn2．x．y039F0．1samplewerestillpurespinel，andthebaSicstructuredidnotchange．ElectrochemicalpropertiesWasstudiedbyaCR2025buttonbatterywhichcomposedofthesamples．Theresultofcharge—dischargetestprovedthatanion-cationdopingcanr

7、educethedisbennifitofthesingleiondoped．TheaveragevalenceofMnWasdecreasedbyFsubstitution，accordingly,theamountofMn3+wereincreased,therefore,theinitialcapacityWaselevated．ThedopedCuandCr,forthebondenergyofM(Cu、Cr)-OisstrongerthanthatofMn-Oandthehigheroc

8、tahedralsitepreferenceenergy,CallbepriortOentertheoctahedralsiteofspinelLiMn204crystallattice，whichmaketheoetahedralstructurestabilization,andreducethedissolvingofMnineletrolyte．Initialdischargecapacityof120．14mAh·g-1and120．08mAh·g‘1wereobtain