Preparation And Electrochemical Properties Of Fe/Co/Ni Based Metal Compound Nanomaterials

In the revolutionary energy market of today,with the rapid consumption of fossil fuels and serious environmental pollution,supercapacitors have become a research hotspot as the most advantageous new-generation energy storage device,and have been rapidly developed in recent years.The core part of the supercapacitor is the electrode material,and the positive and negative materials play a decisive role in the electrochemical performance of the supercapacitor.At the same time,the first transition metal Fe/Co/Ni oxide and its hydroxide have received extensive attention due to their high theoretical capacity.However,due to the problems of poor electrical conductivity and poor reversibility in the charging and discharging process,the actual specific capacity of the material is relatively low.In this paper,nickel-cobalt-based cathode materials and iron-based anode materials with excellent properties were prepared,and then a series of exploration and characterization of its specific formation process and electrochemical performance,including two parts:NiCoAl-LDH?expressed as NCA?nanosheets grown directly on nickel foam substrate were prepared by a simple and efficient hydrothermal method.In addition,the influence of nickel-cobalt ratio on electrochemical performance was investigated by using hydrothermal time as the evolution axis.The characterization results show that nickel foam can not only adjust the ratio of Ni and Co ions as a slow-release nickel source,but also does not change the morphology of the sample.Direct directed growth also avoids loss of active material and increases the active site of the material.The obtained NiCoAl-LDH?Ni:Co-1:1.5?electrode showed an great area capacitance of 5691.25 mF cm^-22 when current density is 1 mA cm^-22 and excellent rate performance(3225 mF cm^-22 at 10 mA cm^-2).The supercapacitor assembled by the prepared positive electrode material NiCoAl-LDH?Ni:Co-1:1.5?and activated carbon cannot meet the requirements of power density and energy density well.Therefore,it is necessary to further prepare a negative electrode material having excellent properties for matching.The composite material Fe₃O₄-Fe@C was prepared with ethylene glycol as solvent.The prepared sample Fe₃O₄-Fe@C has an area specific capacitance of 2358mF cm^-22 at current densities of 1 mA cm^-2.Compared with the electrode material Fe₃O₄-Fe,it can be seen that the carbon-coated sample Fe₃O₄-Fe@C has better electrochemical performance.The activated carbon shell on the surface of iron based oxide can not only provide redundant double-layer capacitance,but also protect the internal structure from damage At the same time,the assembled NCA//Fe₃O₄-Fe@C also showed excellent performance.At a power density of 800.2W kg^-1,the energy density of NCA//Fe₃O₄-Fe@C ACS can reach 176.7 Wh kg^-1,even at a high power density of 16008 W kg^-1,the energy density is still 66.7 Wh kg^-1.