Structural change of LiNi0.5Mn0.5O2 during charge and discharge (1).pdf

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1、ARTICLEINPRESSJournalofPhysicsandChemistryofSolids69(2008)1238–1241www.elsevier.com/locate/jpcsStructuralchangeofLiNi1/2Mn1/2O2duringchargeanddischargeinnonaqueouslithiumcellsKingoAriyoshi,TomohiroIchikawa,TsutomuOhzukuDepartmentofAppliedChemistry,GraduateSchoolofEngineering,OsakaCi

2、tyUniversity(OCU),Sugimoto3-3-138,Sumiyoshi,Osaka558-8585,JapanReceived30June2007;receivedinrevisedform23October2007;accepted30October2007AbstractThestructuralchangeofLiNi1/2Mn1/2O2(a¼2.89A˚,c¼14.31A˚inhexagonalsetting)duringchargeanddischargewasexaminedbymeansofex-situX-raydiffracti

3、on(XRD)measurements.Theintegratedintensityratioofthe(003)to(104)diffractionlinesincreasedfromca.0.9ataninitialstatetoca.1.5whenLiNi1/2Mn1/2O2wasoxidizeduptox¼0.7inLi1xNi1/2Mn1/2O2correspondingtothe1chargecapacityof200mAhgbasedonthesampleweight,whilethechangeinlatticedimensionsofa-a

4、ndc-axiswassimilartothoseofLiCoxNi1xO2.ThechangeintheintensityratioofI(003)/I(104)wasreversiblebetweenca.0.9and1.5duringchargeanddischarge.Fromtheseresults,structuralchangesoflayeredlithiuminsertionmaterialofLiNi1/2Mn1/2O2duringchargeanddischargewerediscussed.r2007ElsevierLtd.Allrig

5、htsreserved.Keywords:A.Oxides;B.Chemicalsynthesis;C.X-raydiffraction;D.Crystalstructure1.Introductionusuallyshowsthedestructiveeffectontheelectrochemicalreactivityofthematerialinlithiumcells.Thelithiumcells1ThelayeredlithiuminsertionmaterialofLiNi1/2Mn1/2O2ofLiNi1/2Mn1/2O2,however,s

6、how200mAhgofre-hasbeenofgreatinterestamongsolid-statechemistsandchargeablecapacitywithgoodcycleability[2,3].InordertoelectrochemistsbecauseofitscomplexnatureofelectronicunderstandthestructureandelectrochemistryofLiNi1/2andcrystalstructureinadditiontothepossiblecandidateMn1/2O2,severa

7、ltrialshavebeendone,suchasin-situasapositiveelectrodeforadvancedlithium-ionbatteries.X-raydiffraction(XRD),neutrondiffraction,MAS-NMRThecrystalstructureofLiNi1/2Mn1/2O2isalayered[4–6],andSQUIDmeasurements[7].Arachietal.[4]structurehavingacubicclose-packedoxygenarray.Thisreportedthatt

8、hesmallamoun