锂电池方面知识点

高电压正极材料LiNi0.5Mn1.5O4的制备及电化学性能引用知识点1.LiMn2O4作为锂离子电池正极材料因其资源丰富，成本低，无毒性，具有较高电压平台，一直受到广泛关注[1–2][1]PARKOK,CHOY,LEES,etal.Whowilldriveelectricvehicles,olivineorspinel[J].EnergyEnvironSci,2011,4:1621–1633.[2]伊廷锋,岳彩波,朱彦荣,等.动力锂离子电池正极材料的研究评述[J].稀有金属材料与工程,2009,38:1687–1692.YITingfeng,YUECaibo,ZHUYanrong,etal.RareMetalMaterEng(inChinese),2009,38:1687–1692.2.但是，由于存在Jahn-Teller效应以及Mn3+的溶解，导致LiMn2O4在循环过程中容量衰减严重，这也成为了制约其发展的重要因素[3–4][3]RODRI´GUEZ-CARVAJALJ,ROUSSEG,MASQUELIERC,etal.Electroniccrystallizationinalithiumbatterymaterial:columnarorderingofelectronsandholesinthespinelLiMn2O4[J].PhysRevLett,98,81:4660–4663.[4]HUANGHT,VINCENTCA,BRUCEPG.CapacitylossoflithiummanganeseoxidespinelinLiPF6/ethylenecarbonate-dimethylcarbon-ateelectrolytes[J].JElectrochemSoc,1999,146:481–485.3.研究发现，通过在LiMn2O4中掺杂少量金属离子形成LiMxMn1.5–xO4型化合物，可以减少材料中Mn3+的含量，从而改善其循环性能。在这些材料中，LiNi0.5Mn1.5O4具有较高的理论容量(146.7mA·h/g)、高电压平台(4.7V)以及优异的循环性能[5–8][5]AMINEK,TUKAMOTOH,YASUDAH,etal.Preparationandelec-trochemicalinvestigationofLiMn2–xMexO4(Me:Ni,Fe,andx=0.51.0)cathodematerialsforsecondarylithiumbatteries[J].JPowerSources,1997,68:604–608.[6]CABALLEROA,CRUZM,HERNA´NL,etal.OxygendeficiencyastheoriginofthedisparatebehaviorofLiM0.5Mn1.5O4(M=Ni,Cu)nanospinelsinlithiumcells[J].JElectrochemSoc,2005,152:A552–A559.[7]刘国强,其鲁.高电压锂离子正极材料的制备和性能[J].电池,2005,35:261–262.LIUGuoqiang,QILu.BatteryBimonthly(inChinese),2005,35:261–262.[8]BHASKARA,BRAMNIKNN,SENYSHYA,etal.Synthesis,char-acterization,andcomparisonofelectrochemicalpropertiesofLiM0.5Mn1.5O4(M=Fe,Co,Ni)atdifferenttemperatures[J].JElec-trochemSoc,2010,157:A689–A695.4.目前，制备LiNi0.5Mn1.5O4材料的方法主要有固相法[9]、溶胶–凝胶法[10]、浸渍法[11]、熔盐法[12]、共沉淀法[13]等。[9]HAGHNM,AMATUCCIGG.Anewsolid-stateprocessforsynthesisofLiMn1.Ni0.5O4−ξspinel[J].JPowerSources,2010,195:5005–5012.[10]SUNYY,YANGYF,ZHANH,etal.SynthesisofhighpowertypeLiMn1.5Ni0.5O4byoptimizingitspreparationconditions[J].JPowerSources,2010,195:4322–4326.[11]ZHOUL,ZHAODY,LOUXW.LiNi0.5Mn1.5O4hollowstructuresashigh-performancecathodesforlithium-ionbatteries[J].AngewChemIntEd,2012,51:239–241.[12]刘贵阳,郭俊明,王宝森,等.低温熔盐燃烧法合成LiNi0.5–xMgx·Mn1.5O4(x=0,0.05)及其电性能[J].硅酸盐学报,2010,38:1398–1400.LIUGuiyang,GUOJunming,WANGBaosen,etal.JChinCeramSoc,2010,38:1398–1400.[13]GAOJ,LIJJ,JIANGCY,etal.Controlledpreparationandcharac-terizationofsphericalLiNi0.5Mn1.5O4cathodematerialforlithium-ionbatteries[J].JElectrochemSoc,2010,157:A899–A902.5.在传统的共沉淀法中，由于Li2CO3微溶于水，合成步骤均为先得到Mn2+、Ni2+的碳酸盐沉淀，洗涤杂质离子后再添加Li+源煅烧，过程比较繁琐[13–15]。[13]GAOJ,LIJJ,JIANGCY,etal.Controlledpreparationandcharac-terizationofsphericalLiNi0.5Mn1.5O4cathodematerialforlithium-ionbatteries[J].JElectrochemSoc,2010,157:A899–A902.[14]SUNAYK,OHSW,YOONCS,etal.EffectofsulfurandnickeldopingonmorphologyandelectrochemicalperformanceofLiNi0.5·Mn1.5O4−xSxspinelmaterialin3-Vregion[J].JPowerSources,2006,161:19–26.[15]OHSW,MYUNGST,KANGHB,etal.EffectsofCodopingonLi[Ni0.5CoxMn1.5−x]O4spinelmaterialsfor5Vlithiumsecondarybat-teriesviaCo-precipitation[J].JPowerSources,2009,189:752–756.6.形成原因为LiNi0.5Mn1.5O4材料在高温煅烧过程中发生歧化反应而失氧，随着温度以及煅烧时间的增加，样品中氧缺陷增多，造成尖晶石相中镍的不足以及部分Mn4+还原成Mn3+[13,16–17]。[13]GAOJ,LIJJ,JIANGCY,etal.Controlledpreparationandcharac-terizationofsphericalLiNi0.5Mn1.5O4cathodematerialforlithium-ionbatteries[J].JElectrochemSoc,2010,157:A899–A902.[16]ZHONGQ,BONAKDARPOURA,ZHANGM,etal.SynthesisandelectrochemistryofLiNixMn2–xO4[J].JElectrochemSoc,1997,144:205–213.[17]SONGJ,SHINDW,LUYH,etal.RoleofoxygenvacanciesontheperformanceofLi[Ni0.5–xMn1.5+x]O4(x=0,0.05,and0.08)spinelcathodesforlithium-ionbatteries[J].ChemMater,2012,24:3101–3109.7.样品的X射线光电子能谱(XPS)曲线在结合能为642.1、642.9eV处存在2个峰，分别对应于Mn3+、Mn4+的结合能[17–18][17]SONGJ,SHINDW,LUYH,etal.RoleofoxygenvacanciesontheperformanceofLi[Ni0.5–xMn1.5+x]O4(x=0,0.05,and0.08)spinelcathodesforlithium-ionbatteries[J].ChemMater,2012,24:3101–3109.[18]WANGDP,CHENH,DUF,etal.ComparativestudiesonstructureandelectronicpropertiesbetweenthermallithiatedLi0.5MnO2andLiMn2O4[J].ChemResChinUniv,2010,26:283–286.8.随着煅烧温度的升高，样品的晶胞参数逐渐增大，这是因为Mn3+的半径(0.065nm)大于Mn4+的半径(0.053nm)。同时，随着温度的升高，产生了更多的Mn3+，使得晶胞的体积相应增大[10][10]SUNYY,YANGYF,ZHANH,etal.SynthesisofhighpowertypeLiMn1.5Ni0.5O4byoptimizingitspreparationconditions[J].JPowerSources,2010,195:4322–4326.9.在4.7V附近的2个放电平台分别对应于Ni2+/Ni3+、Ni3+/Ni4+的氧化还原过程[20][20]ZHONGGB,WANGYY,ZHAOXJ,etal.Structural,electrochemi-calandthermalstabilityinvestigationsonLiNi0.5–xAl2xMn1.5–xO4(0≤2x≤1.0)as5Vcathodematerials[J].JPowerSources,2012,216:368–375.10.在4.1V附近同样存在一个放电平台，这对应于煅烧产生的少量Mn3+和Mn4+间的氧化还原反应[8,11][11]ZHOUL,ZHAODY,LOUXW.LiNi0.5Mn1.5O4hollowstructuresashigh-performancecathodesforlithium-ionbatteries[J].AngewChemIntEd,2012,51:239–241.[8]BHASKARA,BRAMNIKNN,SENYSHYA,etal.Synthesis,char-acterization,andcomparisonofelectrochemicalpropertiesofLiM0.5Mn1.5O4(M=Fe,Co,Ni)atdifferenttemperatures[J].JElec-trochemSoc,2010,157:A689–A695.11.经过高温长时间的煅烧，样品颗粒形成了更多的氧缺陷，出现了更多的Mn3+，而Mn3+是导致材料循环性能差的关键原因[4,21][4]HUANGHT,VINCENTCA,BRUCEPG.CapacitylossoflithiummanganeseoxidespinelinLiPF6/ethylenecarbonate-dimethylcarbon-ateelectrolytes[J].JElectrochemSoc,1999,146: