metal segregation in hierarchically structured cathode materials for high-energy lithium batteries

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1、ARTICLESPUBLISHED:11JANUARY2016

2、ARTICLENUMBER:15004

3、DOI:10.1038/NENERGY.2015.4Metalsegregationinhierarchicallystructuredcathodematerialsforhigh-energylithiumbatteriesFengLin1,DennisNordlund2,YuyiLi1,MatthewK.Quan1,LeiCheng1,3,Tsu-ChienWeng2†,YijinLiu2*,Huolin

4、L.Xin4*1andMarcaM.Doe*IntechnologicallyimportantLiNi1xyMnxCoyO2cathodematerials,surfacereconstructionfromalayeredtoarock-saltstructureiscommonlyobservedunderavarietyofoperatingconditions,particularlyinNi-richcompositions.Thisphenomenoncontributestopoorhigh

5、-voltagecyclingperformance,impedingattemptstoimprovetheenergydensitybywideningthepotentialwindowatwhichtheseelectrodesoperate.Here,usingadvancednano-tomographyandtransmissionelectronmicroscopytechniques,weshowthathierarchicallystructuredLiNi0.4Mn0.4Co0.2O2sph

6、ericalparticles,madebyasimplespraypyrolysismethod,exhibitlocalelementalsegregationsuchthatsurfacesareNi-poorandMn-rich.ThetailoredsurfacesresultinsuperiorresistancetosurfacereconstructioncomparedwiththoseofconventionalLiNi0.4Mn0.4Co0.2O2,asshownbysoftX-rayabs

7、orptionspectroscopyexperiments.Theimprovedhigh-voltagecyclingbehaviourexhibitedbycellscontainingthesecathodesdemonstratestheimportanceofcontrollingLiNi1xyMnxCoyO2surfacechemistryforsuccessfuldevelopmentofhigh-energylithiumionbatteries.
hedevelopmentoflithiu

8、mionbatterytechnologieshas(alsoknownasLMR-NMCsorxLi2MnO3(1x)LiMO2,whereTspurredmajorbreakthroughsinportableelectronics,powerM=Mn,Ni,Coandsoon),LixNi0.8Co0.15Al0.05O2andhigh-tools,electricvehicles,andgridenergystorage.InalithiumvoltagespinelLiNi0.5Mn1.5O4,sur

9、facereconstructionisalsoaioncell,theenergyandpowerdeliveryisachievedbyshuttlingfactorinthepoorCoulombiceciency,andfastcapacityfading8,9,1517lithiumionsbetweenpositiveandnegativeelectrodes,wherethethatisobservedaswellastransitionmetaldissolutionand18activema

10、terialsundergoredoxreactionsusingelectronsfromancomplexation.Ourpreviousdensityfunctionaltheorycalculationsexternalcircuitwithincertainvoltagewindows.Sofar,cathodeindicatedthat,inNMCmater