组会汇报PPT课件

组会汇报,汇报人：陈平平,1,.,研究背景,锂硫电池因具有较高的理论比能量而成为目前最具开发前景的二次电池体系之一。由于电池正极体积膨胀、单质硫及其不溶性产物Li2S2和Li2S导电性低、多硫化物穿梭严重导致缩短电池寿命，成为目前重点解决的问题。目前研究通过将活性物质硫与介孔碳、纳米碳纤维（CNF）、多壁碳纳米管（MWCNTs）、石墨烯、导电聚合物、金属氧化物等具有特定结构的基质材料制备硫基复合正极材料，可以显著改善锂硫电池的循环性能和倍率性能。,2,.,研究意义,锂离子电池是目前商业化二次电池中性能最好的电池体系，但由于其主要使用LiFeO4、LiCoO2和LiNi1/3Co1/3Mn1/3O2等作为正极材料，而这些正极材料的理论容量一般不超过300mAhg-1，难以满足目前对于高比能量电池的需求，因此开发高理论比容量的正极材料成为当今研究的重点。单质硫在常温下主要以S8的形式存在，在地球中储量丰富，具有价格低廉、环境友好等特点。利用硫作为正极材料的锂硫电池，其材料理论比容量和电池理论比能量较高，分别达到1672mAhg-1和2600Whkg-1，目前锂硫电池的实际能量密度已达到390Whkg-1，预计在今后几年内极有可能提高到600Whkg-1，被认为是现在最具研究价值和应用前景的锂二次电池体系之一。,多种杂化材料协同作用越来越成为锂硫电池发展的趋势,参考文献：J.Am.Chem.Soc.2015,137,1294612953NanoLett.2015,15,798802NanoLett.2014,14,48214827Adv.Funct.Mater.2015,25,287297Angew.Chem.Int.Ed.2012,51,35913595,3,.,文献汇报,4,.,Figure1a)SynthesisoftheMnO2HCF/Scomposite.b)AdvantagesoftheMnO2HCF/ScompositeoverHCF/S.,5,.,Figure2)Field-emissionscanningelectronmicroscopy(FESEM)andtransmissionelectronmicroscopy(TEM)imagesofa,d)MnO2SiO2C,b,e)MnO2HCF,andc,f)MnO2HCF/S.,6,.,figure3)XRDpatternsofa)MnO2HCFandc)MnO2HCF/Sandpuresulfur.TGAcurvesofb)MnO2HCFinairandd)MnO2HCF/SinN2atmospherewithaheatingrateof10Cmin1.,7,.,Figure4a)CyclecapacityandCoulombicefficiencyofMnO2HCF/SincomparisonwithHCF/Satacurrentdensityof0.2C.b)Voltageprofilesduringcyclingat0.1C.c)Dischargecapacities.d)Voltageprofilesatvariousratecapabilitiesfrom0.05to1C.e)ProlongedcyclingperformanceofMnO2HCF/Sat0.5CandthecorrespondingCoulombicefficiency.Arealcapacityvalueswerecalculatedbasedonthespecificcapacityandarealmassloadingofsulfur.,ResearchHighlights：highsulfurloadingof3.5mgcm2,8,.,Adv.Mater.2015,27,59365942,9,.,Figure1.a)Schematicillustrationofthespace-confinedsynthesisoftheG/Shybridnanosheets.b)Schematicillustrationofthe“sauna”reactionsystem.c)SketchoftheinterfacialbondingintheG/Shybridnanosheets;grayspheresrepresentcarbonatoms,yellowspheresrepresentsulfuratoms,andpinkbondsrepresentinterfacialbondingbetweengrapheneandsulfur.,10,.,Figure2.a)TEMimageofpristineGO.b)SEMandc)TEMimagesofG/Snanosheets.Theinsetsin(a)and(c)arecorrespondingSAEDpatterns,respectively.d)TheEELSspectrumoftheG/Snanosheets.e)HAADFimageandthecorrespondingCandSelementalmapsfromtheregionindicatedbytheyellowsquare,suggestingtheuniformdistributionofsulfurcontentongraphenesheet.f)XRDpatternsofGOandG/Snanosheets.,B,D,A,C,E,LOREMIPSUMDOLORSITAMETCONSECTETUR,LOREMIPSUMDOLORSITAMETCONSECTETUR,LOREMIPSUMDOLORSITAMETCONSECTETUR,LOREMIPSUMDOLORSITAMETCONSECTETUR,LOREMIPSUMDOLORSITAMETCONSECTETUR,EELS:能分析表面原子、分子的结构和化学特性SAED:选区电子衍射实现晶体样品的形貌特征与晶体学性质的原位分析,11,.,Figure3.High-resolutionC1sXPSspectraofa)GOandb)G/Shybridnanosheets.c)High-resolutionS2pspectrumofG/Shybridnanosheets.AllXPSspectrahavebeenfittedwithGaussianLorentzianwaveforms.d)Comparisonofcore-lossEELSspectraofCK-edgefromGOandG/Shybridnanosheets,acquiredwiththesameTEMandsimilarelectro-opticalconditions.e)RamanspectraofGOandG/Shybridnanosheets.f)TheplanarconductivityversustemperatureprofilesforGOandG/Shybridnanosheets.,sp2sp3,sp2,12,.,Figure5.ElectrochemicalperformanceofG/ShybridmaterialasthecathodeforLiSbattery.a)Cyclicvoltammetry(CV)measuredinapotentialwindowfrom1.5to3.0Vatascanrateof0.1mVs1forthefirst,second,andthirdcycles.b)FirstgalvanostaticchargedischargecurvesoftheG/Scathodeat0.2C(1C=1675mAg1).c)Dischargecapacitiesatdifferentcurrentdensitiesfrom0.2to5CoftheG/Scathode,incomparisonwithpureScathode.d)CyclicperformanceandCoulombicefficiencyoftheG/Scathodeat0.5C,i