Preparation And Electrochemical Properties Of Nitrogen-Doped Mesoporous Hollow Carbon Nanospheres And Its Composites

In this paper,nitrogen-doped mesoporous hollow carbon nanospheres and its composite material loaded spinel NiCo₂O₄ were successfully prepared as electrode materials for supercapacitors.The electrode materials were characterized by X-ray diffraction,Raman spectra,X-ray photoelectron spectroscopy,BET N₂ sorption analysis,Field emission scanning electron microscopy and High-resolution transmission electron microscopy.Cyclic voltammetry,Galvanostatic charge/discharge and electrochemical impedance spectroscopy were used to test the electrochemical performance of the electrode materials.The experiment is divided into two parts.1.Using PMMA-PBMA-PMAA as the soft template,the hollow polypyrrole microspheres were obtained by latex polymerization,then placed the microspheres into nitrogen atmosphere for high-temperature carbonization to obtain the N-MHCNS.And we investigated the effects of different carbonization temperatures on the electrochemical properties of N-MHCNS.Material characterization was used to explore the morphology,internal structure,elemental composition and content of materials.Electrochemical characterization showed that N-MHCNS700 had the best electrochemical performance.The electrochemical performance is as follows:when the current density is 1 A g^-1,the specific capacitance of N-MHCNS700 is 275.7 F g^-1.Even at the current density of 20 A g^-1,its specific capacitance can still maintain 54.4%compared with the current density of 1 A g^-1.After 5000 cycles under the current density of 10 A g^-1,the specific capacitance of N-MHCNS700 have almost no degradation.When the power density of N-MHCNS700 is 500.8 W kg^-1,the energy density is 29.9 Wh kg^-1.So,N-MHCNS700 exhibits good electrochemical properties as the electrode material of supercapacitors.2.N-MHCNS700@Ni-Co-MOF material was prepared by hydrothermal reaction.Then N-MHCNS700@NiCo₂O₄ composite was formed by calcination.Material characterization is used to analyze the morphology and structure of the material.The electrochemical characterization is as follows:when the current density is 1 A g^-1,the specific capacitance of the composite is 996.1 F g^-1.When the current density is 10 A g^-1,the specific capacitance of the composite can still maintain 70.5% compared with the current density of 1 A g^-1.When the power density of composite is 624.9 W kg^-1,the energy density is 42.8 Wh kg^-1.Compared to N-MHCNS700,the performance of composite is improved in specific capacitance and energy density.