FacilesynthesisofthreeOPENSUBJECTAREAS:MATERIALSFORENERGYANDCATALYSISELECTROCHEMISTRYFacilesynthesisofthree-dimensionalstructuredcarbonfiber-NiCo2O4-Ni(OH)2high-performanceelectrodeforpseudocapacitorsWeiLi1,4,LipengXin1,4,XinXu2,4,7,QidaLiu5,MingZhang1,4,ShujiangDing2,4,7,MingshuZhao3,4,6,7&XiaojieLou1,41Received27October2021Accepted19February2021Published19March2021CorrespondenceandrequestsformaterialsshouldbeaddressedtoW.L.(liwei03453@stu.xjtu.edu.cn)orX.L.(xlou03@mail.xjtu.edu.cn)Multi-disciplinaryMaterialsResearchCenter,FrontierInstituteofScienceandTechnology,Xi’anJiaotongUniversity,Xi’an710049,China,2DepartmentofAppliedChemistry,SchoolofScience,Xi’anJiaotongUniversity,Xi’an710049,China,3DepartmentofMaterialPhysics,SchoolofScience,Xi’anJiaotongUniversity,Xi’an710049,China,4AStateKeyLaboratoryforMechanicalBehaviorofMaterials,Xi’anJiaotongUniversity,Xi’an710049,China,5StateKeyLaboratoryforStrengthandVibrationofMechanicalStructures,Xi’anJiaotongUniversity,Xi’an710049,China,6ShaanxiProvinceKeyLaboratoryofAdvancedFunctionalMaterialsandMesoscopicPhysics,Xi’anJiaotongUniversity,Xi’an710049,China,7MOEKeyLaboratoryforNonequilibriumSynthesisandModulationofCondensedMatter,Xi’anJiaotongUniversity,Xi’an,710049,China.Two-dimensionaltexturedcarbonfiberisanexcellentelectrodematerialand/orsupportingsubstrateforactivematerialsinfuelcells,batteries,andpseudocapacitorsowingtoitslargesurfacearea,highporosity,ultra-lightness,goodelectricconductivity,andexcellentchemicalstabilityinvariousliquidelectrolytes.AndNickelhydroxideisoneofthemostpromisingactivematerialsthathavebeenstudiedinpracticalpseudocapacitorapplications.Herewereportahigh-capacitance,flexibleandultra-lightcompositeelectrodethatcombinestheadvantagesofthesetwomaterialsforpseudocapacitorapplications.Electrochemicalmeasurementsdemonstratethatthe3Dhybridnanostructuredcarbonfiber–NiCo2O4–Ni(OH)2compositeelectrodeshowshighcapacitance,excellentratecapability.Tothebestofourknowledge,theelectrodedevelopedinthisworkpossessesthehighestarealcapacitanceof6.04Fcm22atthecurrentdensityof5mAcm22amongthoseemployingcarbonfiberastheconductor.Itstillremains64.23%at40mAcm22.Asforthecyclingstability,theinitialspecificcapacitancedecreasesonlyfrom4.56Fcm22to3.35Fcm22after1000cyclesunderacurrentdensityof30mAcm22.heeverincreasingdemandforportableelectronicequipment,andelectricorhybridelectricvehicles,aswellastheconcernsofenvironmentalpollutionhavestimulatedtherapiddevelopmentoftheelectro-chemicalenergystorageandconversiondevices(EESCs).Thesedevicestypicallyincludelithium-ionbatteriesandpseudo-capacitors1–4.Inparticular,pseudo-capacitors,asatypicalrepresentativeofEESCs,havebeenwidelystudiedduetotheirnumerousmerits,suchasfastchargeanddischargeproperties,longservicelifeandhighpowerdensity,widerangeworkingtemperature,highsafetyandtheenvironmentallyfriendlyfeature5,6.Inthedevelopmentofpseudo-capacitors,electrodematerialsarewellknownasoneofthekeyfactorsaffectingtheirelectro-chemicalperformance7,8.Sofar,mostoftheinvestigationshavefocusedonutilizingmetals(e.g.,Nifoil,Nifoam,Tifoil,Cufoil,etc.)asthecurrentcollectorandtransitionmetaloxides(e.g.,NiO,NiOH,CoO,Co4O3,NiCo2O4,MnO2)asactivematerialstofabricatehigh-performanceelectrodesofpseudocapacitors9–15.Theseelectrodematerialswerefoundtoexhibitimpressivepseudo-capacitiveperformance.Amongallthosem...