Synthesis And Supercapacitive Performance Of Cobalt-based And Fe-based Metal Oxide Nanoarrays

The increasingly environmental problems and energy crisis have accelerated the extensive research on new energy sources and efficient conversion and storage devices.Due to high power density,fast charge/discharge rate,long cycle life and environmental friendliness,supercapacitor have become the most promising new green energy storage devices in the fields of portable electronic equipment and new energy.However,subject to the electrode material itself,the energy density of the supercapacitor is relatively low.In this paper,the controlled growth of the electrode material structure and morphology is taken as the research point,and the transition metal oxide with high specific capacitance is selected as the research object.The nano-array electrodes directly grown on a three-dimensional current collector is obtained.The purpose is to develop positive and negative electrode materials with high specific capacitance,and through reasonable matching,further construct energy storage devices with high power density and excellent comprehensive ability.The main contents are as follows:?1?CuCo₂O₄ nanoneedle array material supported on nickel foam with unique hierarchical structure and good porosity was prepared by a simple hydrothermal method combined with subsequent annealing treatment.By adjusting the reactant concentration,the CuCo₂O₄ nanoneedle array material with a series of advantages such as large electrochemically active surface area,good electrical conductivity and fast ion transmission rate were obtained.After testing,it can deliver a specific capacity of 2.62 F cm^-2(1747 F g^-1)at 1m V s^-1 and remarkable cycle stability?164%retention after 70 000 cycles?.In addition,the assembled CuCo₂O₄//AC device can achieve a high energy density of 57 Wh kg^-1 while maintaining the inherently high power density.Moreover,the capacity remains 83.9%after 10000 cycles.Based on this,the obtained CuCo₂O₄ nanoneedle array material is a promising supercapacitor electrode material.?2?Through reasonable morphological design,a three-dimensional Fe₂O₃nanorod array on porous titanium foam was obtained by hydrothermal method and annealing treatment as a binder-free negative electrode for high-performance supercapacitors.The rich three-dimensional porous structure of the titanium foam provides sufficient space for the growth of the active material,which greatly improves the surface load.In addition,it is the directionally ordered nanoarray architecture of material that provides efficient electron transport and great active surface area,showing a higher specific capacity(8.186 F cm^-2(1488 F g^-1)).Subsequent simple carbon layer coating successfully solved the problem of poor cycle stability of the rubidium capacitor material?cycles up to 5000 times?,thereby obtaining a supercapacitor negative electrode material with high electrochemical performance.This special morphology nano-active material grows directly to the design of a three-dimensional metal current collector with a special structure,which provides a new idea for the preparation of high-performance supercapacitor electrode materials.?3?The Co-doped Fe₂O₃ nanorod array material grown on titanium foam was modified with different concentrations of Co²⁺on basic of synthesizing pure Fe₂O₃nanorod array material.The comparative analysis of sample morphology and phase before and after doping proved that Co²⁺was successfully doped into the Fe₂O₃crystal Structure.Subsequent electrochemical tests show that the Fe₂O₃ samples after Co²⁺doping have better electrochemical performance.And at the optimal concentration,the area-specific capacitance of the sample after Co²⁺doping at 1 mV s^-1 reaches 15.79 F cm^-2,which is much higher than the capacity of Fe₂O₃(8.18 F cm^-2).It provides an effective way to design supercapacitor electrode materials with higher energy density.