1、Cite this:NewCarbonMaterials,2023,38(3):510-521DOI:10.1016/S1872-5805(23)60731-0A bimetallic sulfide Co9S8/MoS2/C heterojunction in a three-dimen-sional carbon structure for increasing sodium ion storageCHENHong,MUJian-jia,BIANYu-hua,GAOXuan-wen*,WANGDa,LIUZhao-meng,LUOWen-bin*（Institute for Energy
2、Electrochemistry and Urban Mines Metallurgy,School of Metallurgy,Northeastern University,Shenyang 110819,China）Abstract：Thesynthesisofhigh-rateandlong-lifeanodematerialsforsodiumionbatteries(SIBs)hasattractedmuchattention.However,theslowkineticsandlargeincreaseinvolumeofthebatteriesremainmajorproble
3、ms.Bothmetal-organicframeworksandMoS2haveshownpropertiessuitableforSIBs,makingresearchontheircompositesystemsanattractiveareaofresearch.Wereporttheformationofflower-likeCo9S8/MoS2/Ccompositesbyasimultaneousvulcanization-carbonizationprocessusingMoCl5astheMosourceanda2-methylimidazolecobaltsaltastheC
4、oandCprecursoratdifferenttemperatures（600,700and800C）insub-limedsulfur.Theeffectoftheheterojunctiononthediffusionkineticswasanalyzedusingdensityfunctionaltheory.Theresultsin-dicatethattheelectronicstructureisdifferentattheinterfaceintheheterogeneousstructure,exhibitingtypicalmetallicpropertiesandbet
5、terelectronicconductivity.Inaddition,theanodematerialCo9S8/MoS2/Csynthesizedat700Chadthemoststablestructureandbestelectrochemicalperformanceofthethreesamples.Notably,thedischargecapacityofCo9S8/MoS2/C-700fullyrecoveredfrom368to571mAhg1andthenstabilizedat543mAhg1whenthecurrentdensitywasrestoredfrom40
6、00to40mAg1.Thisworkdemonstratesthepreparationofheterojunctionmaterialsforcompositeanodematerialsasasteptoproducinghigh-performancemet-alSIBs.Key words:Sodiumionbatteries；Anode；Metal-organicframe；MoS2；Co9S81IntroductionLithium-ionbatteries are now commonly em-ployed in portable consumer electronics g
7、adgets aswellasemergingelectricvehicles12.However,themassiveriseoflithium-ionbatteries(LIBs)impliesajumpinlithiumresourceprices,aswellasalimitedandunevendistributionoflithiumreservesaroundtheglobe,limitingthedevelopmentofLIBs35.Duetotheirabundantmaterialsandsimilaritywithlithiumschemistry,sodium-ion
8、batteries(SIBs)havedrawnagreatdealofinterestandareconsideredcapableofpartiallyreplacingLIBs67.Transitionmetalsulfides(TMS)havereceivedagreatdealofattentionasan-odematerialsforSIBsduetotheirenormoustheoret-icalcapacityandhighsafety,aswellastheirhigherelectricalconductivityandfastercharge-dischargere-
9、actionkineticsthanoxides.Amongrecentlyproducedanodematerials,MoS2isaclassicexampleofTMS,withsimplepreparation,abundantrawmaterials,highinterlayerspacing(0.62nm)andweakinterlayervanderWaalsforces811.TMSdoes,however,havesev-eral flaws.On one hand,TMS experiences severevolumeexpansionduringchargeanddis
10、charge,caus-ingcyclestabilitytobepoor12.Ontheotherhand,al-thoughthanoxides,TMShavegenerallylowercon-ductivitywhichcausesdelayedelectrochemicalreac-tionkineticsandresultsininadequaterateperform-ance1314.Theconstruction of heterogeneous metal sulf-idesisaneffectivemethodforaddressingthedraw-backoflowe
11、lectricalconductivity1516.Whencom-pared to single-phase metal sulfides,heterogeneousmetalsulfidescannotonlypromotethecreationofaninternalelectricfield,butalsoenhancetheactivityofelectrochemicalreactions at the heterointerface,in-Received date：2023-01-05；Revised date：2023-02-28Corresponding author：GA
12、OXuan-wen,AssociateProfessor.E-mail:;LUOWen-Bin,Professor.E-mail:Author introduction：CHENHong,Ph.Dcandidate.E-mail:Supplementarydataassociatedwiththisarticlecanbefoundintheonlineversion.第38卷第3期新型炭材料（中英文）Vol.38No.32023年6月NEWCARBONMATERIALSJun.2023creasing electrical conductivity1719.It can also im-pr
13、ovecrystallinityattheheterointerface,aswellasin-ducelattice mismatches,distortions and defects,al-lowingthereactionkineticsofelectrodematerialstobe tuned2022.Due to the continuous insertion andconversion/alloying reaction in SIBs,there is rapidvolume change of electrode materials.To solve theabovepr
14、oblems,porousnanostructureengineeringcanbeconstructedtoimprovethestabilityofsodiumstor-ageperformanceofmixedmetalsulfides.Metal-organicframeworks(MOFs),asporousin-organic-organic hybrid materials with high specificsurfacearea,controllablestructure,andtunableporesize,arewidelyusedasprecursorsforthepr
15、eparationofcarbon-metalormetalsulfidecomposites2325.Ingeneral,MOFsexhibitimpressiveperformanceasact-ivematerialsforenergystorageduetotheircomplexandvariedstructuraladvantages2628.Moreover,thenanostructureofMOFscannotonlyshortenthediffu-sionpathofNaions,butalsowithstandthevolumeexpansioncausedbythein
16、sertionofNaions,provid-ingastablesupportfortheoverallstructure2829.Withtheaimofovercomingtheweaknessesofany single component,in this work,a flower-likeCo9S8/MoS2/Ccompositewasdesignedandconstruc-ted by a simultaneous vulcanization-carbonizationmethodatdifferenttemperaturesusingCo-ZIFaspre-cursorandaddingMosource.Bysystematicallyin-vestigatingtheeffectofsulfurvacanciesandmicroto-pography on sodium storage behaviour,the flower-likeCo9S8/MoS2/Cmicrospheresformedbyintercon-nectednanosheetarrays(Co9S
