Ni(OH)2 Nanoplates Grown on Graphene as Advanced

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1、PublishedonWeb05/05/2010Ni(OH)2NanoplatesGrownonGrapheneasAdvancedElectrochemicalPseudocapacitorMaterialsHailiangWang,HernanSanchezCasalongue,YongyeLiang,andHongjieDai*DepartmentofChemistryandLaboratoryforAdVancedMaterials,StanfordUniVersity,Stanford,California94305ReceivedMarch17,2010;E-mail:hd

2、ai@stanford.eduAbstract:Ni(OH)2nanocrystalsgrownongraphenesheetswithvariousdegreesofoxidationareinvestigatedaselectrochemicalpseudocapacitormaterialsforpotentialenergystorageapplications.Single-crystallineNi(OH)2hexagonalnanoplatesdirectlygrownonlightlyoxidized,electricallyconductinggrapheneshee

3、ts(GS)exhibitahighspecificcapacitanceof∼1335F/gatachargeanddischargecurrentdensityof2.8A/gand∼953F/gat45.7A/gwithexcellentcyclingability.Thehighspecificcapacitanceandremarkableratecapabilityarepromisingforapplicationsinsupercapacitorswithbothhighenergyandpowerdensities.Asimplephysicalmixtureofpre-

4、synthesizedNi(OH)2nanoplatesandgraphenesheetsshowslowerspecificcapacitance,highlightingtheimportanceofdirectgrowthofnanomaterialsongraphenetoimpartintimateinteractionsandefficientchargetransportbetweentheactivenanomaterialsandtheconductinggraphenenetwork.Single-crystallineNi(OH)2nanoplatesdirectly

5、grownongraphenesheetsalsosignificantlyoutperformsmallNi(OH)2nanoparticlesgrownonheavilyoxidized,electricallyinsulatinggraphiteoxide(GO),suggestingthattheelectrochemicalperformanceofthesecompositesisdependentonthequalityofgraphenesubstratesandthemorphologyandcrystallinityofthenanomaterialsgrownont

6、op.Theseresultssuggesttheimportanceofrationaldesignandsynthesisofgraphene-basednanocompositematerialsforhigh-performanceenergyapplications.Introductionenergydensity.However,such“pseudocapacitors”oftenresultincompromisesofratecapabilityandreversibilitybecausetheyTheincreasingdemandforenergyandgro

7、wingconcernsrelyonfaradicredoxreactionsandtheactivematerialsareaboutairpollutionandglobalwarminghavestimulatedintensetypicallytooinsulatingtosupportfastelectrontransportrequiredresearchonenergystorageandconversionfromalterna