The Preparation And Capacitive Performances Of Faradic Transition Metal Compounds

Supercapacitors represent a significant category of energy storage and management devices,which store and deliver charges through the electric double layer at electrode surface and the intrinsic faradic reactions of electrode material.The accessible surface area,redox activity and conductivity of electrode material directly determine the capacitive performance of the pertinent supercapacitor.Hence,the preparation of efficient electrode materials via rational strategies is currently the major tasks in supercapacitor fields.This paper mainly involves the preparation of faradic materials with high capacitance,as well as the energy storage performances in assymetric supercapacitors.The main research contents of this thesis are summarized as follows:1.Block copolymer（P123）micelles were employed as ordered microreactors governing the soluabilization of reactants and the confined hydrothermal reaction and assembly of deposition of ternary CN_7:3-rGO composite porous nanowire arrays onto Ni foam substrate.The as-prepared ternary composite owns highly accessible surface area and short electrons/ions migration path lengths,which are especially beneficial for the surface related faradic reactions of Co,Ni components,therefore enable superior specific capacitance,good rate capability and cycleability.Furthermore,the asymmetric supercapacitor based on this faradic CN_7:3-rGO positive electrode delivers competitive energy density(E_cell)and power density(P_cell),as well as good cycleability,showing the potential of the faradic composite porous nanowire arrays electrode in electrochemical energy storage.2.Al doped Co hydroxyl fluoride（Al-Co（OH）F）active layer was prepared and deposited onto Ni foam substrate through a one-step hydrothermal reaction.The active material exhibits intertwined nanosheets with porous framework,and the incorporated F also increases the surface polarity and the hydrophilicity,thus ensures the sufficient contact between electrode and electrolyte as well as the rapid faradic reaction of Co sites and further superior faradic capacitive performance.From the controlled experimentals,the reaction temperature,Co:Al feeding molar ratio and the dosage of F element significantly determine the phase,morphology and therefore the capacitive performance.The asymmetric supercapacitor based on this faradic Al-Co（OH）F electrode and electric double layered rGO electrode can deliver balanced energy,power delivery ability and good cycleability,showing the good capacitive performance of this faradic electrode.3.The composite active layer based on NiAl layered hydroxide carbonates and rGO was prepared and deposited onto Ni foam substrate through a one-step hydrothermal synthesis,the further optimization of Ni:Co feeding molar ratio and reaction temperature generated NA1:1-rGO electrode with optimal capacitive performance,the electrode can offer a high areal capacitance of Active material directly grow on the collection of nickel foam fluid,after further optimized mole ratio of 2.66 F cm^-2 and superior electrochemical stability in alkali electrolyte system,a 72.5%initial capacitance maintaining ratio is ensured undergoes 5000charge-discharge cycles,manifesting the potential of the faradic electrode in supercapacitor.