应用恒流充放电、非现场X射线粉末衍射 (ex situXRD)、电化学交流阻抗 (EIS)、程序控温脱附 质谱联用(TPD MS)等实验方法研究LiNi0. 8-yTiyCo0. 2O2电极材料钛离子的掺杂作用机理.结果表明,掺钛后的电极材料于充放电过程中的结构相变和晶格的膨胀收缩受到抑制,在高电位下的界面反应活性减弱,从而减小了由结构变化和界面反应引起的容量损失;同时,钛的掺杂增强了电极材料在脱锂状态下的结构稳定性,抑制了电极材料和电解液的分解或氧化反应,以上两个方面分别改善并提高了电极材料的充放电循环性能及其热稳定性.
Improved cycling performance and enhanced thermal stability were observed for Ti-doped LiNi_(0.8)Co_(0.2)O_2 cathode materials. The mechanism of these positive effects was investigated in this work. The improved cycling performance of Ti-doped cathodes is ascribed to the suppression of phase transitions and lattice changes during cycling, and the decrease of interfacial reaction activity between the cathode and electrolyte. The enhanced thermal stability of Ti-doped cathodes is attributed to the suppression of thermal decomposition reaction of delithiated cathode material, which will produce heat and oxygen gas as the cause of electrolyte decomposition and combustion reaction.
[1] ChangCC,KimJY,KimPN.Divalentcationincor poratedLi(1+x)MMgxO2(1+x)(M=Ni0.75Co0.25): viablecathodematerialsforrechargeablelithium ionbatteries[J].J.PowerSource,2000,89:56~63.
[2] YoshioM,NoguchiH,ItohJ, etal.PreparationandpropertiesofLiCoyMnxNi1-x-yO2 asacathodeforlithi umionbatteries[J].J.PowerSource,2000,90:176~181.
[3] MadhaviS,SubbaGV,ChowdariB, etal.Effectofa luminiumdopingoncathodicbehaviourofLiNi0.7Co0.3O2[J].J.PowerSource,2001,93:156~162.
[4] PradoG,FournesL,DelmasC.OntheLixNi0.70Fe0.15Co0.15O2 system:AnX raydiffractionandM ssbauerstudy[J].J.SolidStateChem.,2001,159:103~112.
[5] D′EpifanioA,CroceF,RonicF, etal.Thermal, elec trochemicalandstructuralpropertiesofstabilizedLiNiyCo1-y-zMzO2 lithium ioncathodematerialpre paredbyachemicalroute[J].Phys.Chem.Chem.Phys.,2001,3:4399~4403.
[6] ParkSH,ParkKS,SunYK, etal.StructuralandelectrochemicalcharacterizationoflithiumexcessandAl dopednickeloxidessynthesizedbythesol gelmeth od[J].ElectrochemicaActa,2001,46:1215~1222.
[7] FeyGT,SubramanianV,ChenJG.ElectrochemicalperformanceofSr2+ dopedLiNi0.8Co0.2O2 asacathodematerialforlithiumbatteriessynthesizedviaawetchemistryrouteusingoxalicacid[J].MaterialsLetters,2002,52:197~202.
[8] OhzukuT,UedaA,YamamotoN.Zero straininsertionmaterialofLi[Li1/3Ti5/3]04 forrechargeablelithiumcells[J].J.Electrochem.Soc.,1995,142:1431~1435.
[9] KajiyamaA,TakadaK,AriharaK, etal.Synthesisandelectrochemicalpropertiesoflithiumchromiumtita niumoxidewithramsdellitestructure[J].J.Electro chem.Soc.,2003,150:A157~A160.
[10] KimJ,AmineK.TheeffectoftetravalenttitaniumsubstitutioninLiNi1-xTixO2(0.025≤x≤0.2)system[J].ElectrochemistryCommunications,2001,3:52~55.
[11] KimJ,AmineK.Acomparativestudyonthesubstitu tionofdivalent, trivalentandtetravalentmetalionsinLiNi1-xMxO2(M =Cu2+,Al3+ andTi4+)[J].J.PowerSource,2002,104:33~39.
[12] CroguenecL,SuardE, willamannP, etal.StructuralandelectrochemicalcharacterizationoftheLiNi1 yTiyO2 electrodematerialsobtainedbydirectsol id statereactions[J].Chem.Mater.,2002,14:2149~2157.
[13] GaoY,YakovlevaM,EbnerW.NovelLiNi1 xTix/2Mgx/2O2 compoundsascathodematerialsforsaferlith ium ionbatteries[J].ElectrochemandSolidStateLetters,1998,1:117~119.
[14] ChowdariB,RaoG,ChowSY.Cathodicbehaviorof(Co,Ti,Mg) dopedLiNiO2[J].SolidStateIonics,2001,140:55~62.
[15] LiuHS,LiJ,ZhangZR, etal.Structural, electro chemicalandthermalpropertiesofLiNi0.8 yTiyCo0.2O2ascathodematerialsforlithiumionbatteries[J].ElectrochimicaActa,2004,49:1151~1159.
[16] LiuHS,ZhangZR,GongZL, etal.AcomparativestudyofLiNi0.8Co0.2O2 cathodematerialsmodifiedbylatticedopingandsurfacecoating[J].SolidStateI onics,2004,166:317~325.
[17] LiuHS,LiJ,ZhangZR, etal.Theeffectsofsinte ringtemperatureandtimeonthestructureandelectro chemicalperformanceofLiNi0.8Co0.2O2 cathodemate rialsderivedfromsol gelmethod[J].JournalofSolidStateElectrochemistry,2003,7:456~462.
[18] OhzukuT,VedaA,NagayamaM.ElectrochemistryandstructuralchemistryofLiNiO2(R3m) for4Voltsecondarylithiumcells[J].J.Electrochem.Soc.,1993,140(7):1862~1869.
[19] LiW,CurrieJC.Morphologyeffectsontheelectro chemicalperformanceofLiNi1-xCoxO2[J].J.Elec trochem.Soc.,1997,144:2773~2779.
[20] AurbachD,LeviM,LeviE, etal.Commonelectroa nalyticalbehaviorofLiintercalationprocessesintographiteandtransitionmetaloxides[J].J.Electro chem.Soc.,1998,145:3024~3034.
[21] LeviM,SalitraG,MarkovskyB, etal.Solid stateelectrochemicalkineticsofLi ionintercalationintoLi1-xCoO2:Simultaneousapplicationofelectroanalyti caltechniquesSSCV,PITT, andEIS[J].J.Electro chem.Soc.,1999,146:1279~1289.
[22] ChenCH,LiuJ,AmineK.Symmetriccellapproachandimpedancespectroscopyofhighpowerlithium ionbatteries[J].J.PowerSources,2001,96:321~328.
[23] AraiH,OkadaS,SakuraiY, etal.ThermalbehaviorofLi1 yNiO2 andthedecompositionmechanism[J].SolidStateIonics,1998,109:295~302.
[24] AraiH,TsudaM,SaitoK, etal.Thermalreactionsbetweendelithiatedlithiumnickelateandelectrolytesolutions[J].J.Electrochem.Soc.,2002,149:A401~A406.
