Synthesis And Properties Of Cobalt Based Electrode Materials For Supercapacitors

Supercapacitors,as a new and most promising energy storage device,their high power density,fast charge and discharge,good cycle stability and safety have become effective ways to solve the energy crisis and the energy storage of wearable devices.However,the lower energy density seriously hinders the wide market application of supercapacitors.In general,electrode materials play an vital role in the performance of supercapacitors,such as specific capacity,energy density and cycle stability.Thus,the development or regulation of electrode materials with excellent electrochemical properties such as high energy density and excellent stability has become the main research focus of supercapacitors.Cobalt-based materials were called ideal electrode materials because of their high theoretical specific electric capacity,abundant storage capacity and environmental friendliness.However,its poor conductivity and stability limit its application in the field of supercapacitors.In this work,the structure of cobalt-based electrode materials and the control of active substances were constructed CoP@Ni（OH）₂·0.75H₂O core-shell nanosheets,MOF derived Zn O/C@（Ni,Co）Se₂core-shell nanosheets and MOF derived Ni Co Mn ternary metal hydroxide nanosheets as electrode materials,the specific research process are as follows:（1）In this work,CoP@Ni（OH）₂·0.75H₂O core-shell nanosheet electrode material was successfully fabricated on carbon cloth by classic hydrothermal,low-temperature phosphating and electrodeposition method.The valence state composition and morphology details of CoP@Ni（OH）₂·0.75H₂O core-shell nanosheets were analyzed by various types of equipment.The performance test results displayed that at 1 A g^-1,the specific capacity of CoP@Ni（OH）₂·0.75H₂O core-shell nanosheets electrode can reach 168.61 m A h g^-1.The CoP@Ni（OH）₂·0.75H₂O//AC asymmetric supercapacitor constructed with activated carbon（AC）obtained an energy density is 33.78 W h kg^-1and the power density is 800 W kg^-1.Besides,after 10,000 charges and discharges,the capacitance retention rate of the device is up to 98.5%.The above test results shown that the CoP@Ni（OH）₂·0.75H₂O//AC asymmetric supercapacitor device has broad application prospects.（2）In this article,MOF-derived Zn O/C@（Ni,Co）Se₂ core-shell nanosheets were loaded onto carbon cloth substrates by multi-step hydrothermal and selenide method.The prepared Zn O/C@（Ni,Co）Se₂ core-shell nanosheet electrode was characterized in detail by different instruments and electrochemical performance was tested by the electrochemical method.At 1 A g^-1,the specific capacity is 164.18 m A h g^-1.Besides,when the power density is 800 W kg^-1,the high energy density of the Zn O/C@（Ni,Co）Se₂//AC asymmetric supercapacitor device was 58.42 W h kg^-1.After10,000 cycles at 10 A g^-1,the capacitance retention rate of this asymmetric supercapacitor device can reach 97.87%.（3）In this paper,a simple static method and hydrothermal method were used to manufacture the structure of MOF-derived Ni Co Mn ternary metal hydroxide nanosheets on the carbon cloth substrate,and different instruments were used to test the valence states and electrochemical properties of the material in detail.The electrochemical test outcome exhibited that the outstanding electrochemical capacity of the electrode is 422.5 m A h g^-1 at 1 A g^-1.However,the Ni Co Mn（OH）₆//AC asymmetric supercapacitor device constructed by Ni Co Mn ternary metal hydroxide nanosheets and AC has an outstanding energy density is 61.56 W h kg^-1 at 800 W kg^-1,and a capacitance retention rate of 85.26%can be obtained after 10,000 charge-discharge cycles.These results fully prove that the prepared MOF-derived Ni Co Mn ternary metal hydroxide nanosheets electrode has great application potential.