Preparation And Research Of Composite Electrode Materials For Nickel-Cobalt-based High Performance Supercapacitor

Supercapacitor are characterized by high specific capacitance,high energy density and long service life,which make them play an important role in energy storage devices.High performance electrode materials are the material basis of ultracapacitors.Nickel-cobalt nanomaterials,such as hydroxyl fluoride,sulfides and their composites,have shown great potential in the field of electrochemical capacitors due to their high capacitance,high REDOX activity,low cost and environmental friendliness.However,its application in energy conversion and storage is limited by its easy agglomeration and poor conductivity.Therefore,nickel-cobalt nanomaterials and high-conductivity nickel foam?NF?were combined to give full play to their respective advantages,improve the conductivity of the composite and the dispersibility of nickel-cobalt nanomaterials,and thus significantly improve the electrochemical performance of the composite.This paper focuses on the preparation and electrochemical properties of new nickel-cobalt nanocomposites,and the main research results are as follows:NiCoFe layered double hydroxides?NiCoFe-LDH? was directly grown on NF surface to obtain“sand rose”type porous network structure composite material?NiCoFe-LDH/NF? by hydrothermal method.Studies on CV,EIS and GCD showed that the cycle stability,charge and discharge performance and discharge specific capacity of NiCoFe-LDH/NF electrode were significantly improved.Among them,the“sand rose”structure of NiCoFe-LDH/NF₁with a Ni/Co/Fe molar ratio of 1:1:1 is the most uniform and loose,with good dispersion,and therefore has the highest specific capacitance(1387.6 F·g^-1,1A·g^-1),under 10 A·g^-1,after 5000 cycles test,the specific capacitance retention rate is 91.44%.NiCoZn?OH?_xF was coated on NF surface by hydrothermal method to obtain 3D sea urchin shape NiCoZn?OH?_xF composite.Electrochemical studies have found that N₁C₁Z₁?OH?_xF with a Ni/Co/Zn molar ratio of 1:1:1 has the most excellent charge-discharge performance and cycle stability.At 1 A?g^-1,the specific capacitance is as high as 1592.7 F?g^-1,while at 20.0 A?g^-1,the specific capacitance is still up to1106.7 F?g^-1.At 10 A?g^-1,the specific capacitance retention rate was 95.48%after5000 cycles.The NiCoZn?OH?_xF precursor was further vulcanized,and the prepared 3D"chrysanthemum"-like sulfide Ni Co Zn S was used as a supercapacitor electrode and was subjected to electrochemical tests.N₁C₁Z₁S with a Ni/Co/Zn molar ratio of 1:1:1shows excellent electrochemical performance.At 1.0 A?g^-1,the specific capacitance is as high as 2642.2 F?g^-1.At 10 A?g^-1,there is no significant attenuation of the specific capacitance after 5000 cycles,and it still maintains 94.47%of its initial specific capacitance.Finally,NiCoFe-LDH was deposited on the surface of NiCoZnS by hydrothermal method,the corresponding composite material NiCoZn@NiCoFe-LDH was prepared,and the structure of the material was characterized.It was found that NiCoFe-LDH was coated on the surface of NiCoZnS to form"sand rose"core-shell material.The core-shell material can improve the conductivity of the active material and shorten the diffusion path of electrons,and its discharge capacity and cycle performance are greatly improved.At 1.0 A?g^-1,the N₁C₁Z₁S@NiCoFe-LDH specific capacitance is as high as 3180.0 F?g^-1.At 10 A?g^-1,the specific capacitance of 5000cycles retains its initial 94.88%.