Preparation And Electrochemical Properties Of Nanocomposites Based On Cobaltate Template

People's demand for energy is increasingly larger with the rapid development of economy.Simultaneously,their pursuit of life quality is much higher than before.The sharp development of economy has brought a lot of problems,such as the shortage of natural resource and the heavy polluted natural environment,which catches people's attention and trigger a hot topic.As a result,a large amount of scholars do explore and study the problems,in order to find the ways to solve them.Supercapacitor was born in the right moment in such a tense situation.Supercapacitor,which is energy saving and environmental protection,is a newly storage for energy.It holds the traits of high power density,long cycle life and fast charging and discharging,and etc.In this paper,cobaltates nanocomposite electrode materials were prepared by using a nickel foam as the substrate and cobaltates as template.Besides that,the factors such as synthesis conditions,material structure and electrochemical properties were also discussed.The main works of this subject are as follows:1.The magnesium cobaltate?MgCo₂O₄?template was synthesized by hydrothermal method based on nickel foam and modified by in situ oxidative polymerization of pyrrole.Also,orthogonal experiments were designed to investigate the effects of reaction temperature,time,amount of pyrrole addition,electrolyte solution selection and other factors on the properties of electrode materials,so as to obtain the optimal MgCo₂O₄@PPy nanocomposite electrode materials.Characterize the structure and morphology of the prepared electrode materials by using XRD,FTIR,TGA,BET,FE-SEM,TEM and XPS,and etc.The results demonstrated that the composite materials have better physical and chemical structure than single material.Simultaneously,electrochemical tests,such as cyclic voltammetry?CV?,galvanostatic charge-discharge?GCD?and electrochemical impedance spectroscopy?EIS?,and etc.,were performed on the prepared electrode materials.The results shows that MgCo₂O₄@PPy electrode material has a specific capacitance of 1079.6 F g^-11 at a current density of 1 A g^-1,which is better than that of the pure MgCo₂O₄(783.6 F g^-1),and it holds a capacitance of 97.4%of the initial one after 1000 cycles.Moreover,assemble the composite electrode material to an all-solid-state supercapacitor,and do electrochemical tests performance on it.The experiment proves that the prepared capacitor has a higher energy density(33.4 Wh kg^-1)and an excellent cyclic stability?91%?.What counts is that it lighted the LED successfully.From the above,it can be seen that MgCo₂O₄@PPy as the electrode material of supercapacitor has a profound meaning.2.Do pretreatment on the foams.Synthesize magnesium cobaltate?MgCo₂O₄?template on nickel foam with a simple hydrotherma method,then using the same method to synthesize NiMoO₄ nanomaterial.Finally,the MgCo₂O₄@NiMoO₄nanocomposite electrode materials were obtained.Characterize the structure and morphology of the prepared electrode materials by using XRD,FTIR,TGA,BET,FE-SEM,TEM and XPS,and etc.Electrochemical tests,such as cyclic voltammetry?CV?,galvanostatic charge-discharge?GCD?and electrochemical impedance spectroscopy?EIS?,and etc.,were performed on them after that.MgCo₂O₄@NiMoO₄electrode material has a specific capacitance of 1775 F g^-11 at a current density of 1 A g^-1,which is superior to the pure MgCo₂O₄ electrode material(929.7 F g^-1).The capacitance retention rate of MgCo₂O₄@NiMoO₄ electrode material is 75.4%after2000 cycles while the MgCo₂O₄ only has 68.7%.Furthermore,assemble the prepared composite material to all-solid-state supercapacitor and do electrochemical tests on it.The result shows that it holds a high energy density(37.5 Wh kg^-1)and a good cyclic stability?71.7%?.In addition,it not only drove the small motor bust also lighted the LED successfully.All these above can prove that MgCo₂O₄@NiMoO₄ electrode material possesses potential value in practical application.3.The copper cobaltate?CuCo₂O₄?precursor was synthesized with a simple and effective hydrothermal method on nickle foam.Magnesium molybdate?MgMoO₄?was then synthesized on the precursor with hydrothermal method so as to obtain the CuCo₂O₄@MgMoO₄ nanocomposite electrode materials.Test the structure and morphology of the electrode materials by using XRD,FTIR,TGA,BET,FE-SEM,TEM and XPS,and etc.Electrochemical tests,such as cyclic voltammetry?CV?,galvanostatic charge-discharge?GCD?and electrochemical impedance spectroscopy?EIS?,and etc.,were performed on them after that.CuCo₂O₄@MgMoO₄ electrode material has a specific capacitance of 1153 F g^-11 at a current density of 1 A g^-1,which is superior to the pure CuCo₂O₄ electrode material(856 F g^-1).The capacitance retention rate of CuCo₂O₄@MgMoO₄ electrode material is 76.6%after 2000 cycles.It is also higher than that of the pure one?70.1%?.Then,assemble the prepared composite material to all-solid-state supercapacitor and do electrochemical tests on it.The assembled supercapacitor,which lighted the LED successfully,demonstrates a high energy density(24.9 Wh kg^-1)and a good cyclic stability?82.5%?.These can manifest that CuCo₂O₄@MgMoO₄ electrode material has a great potential in practical application.