Preparation And Electrochemical Properties Of Transition Metal (Manganese,Iron) Oxide/Carbon Matrix Composites

In this paper,the transition metal?Mn,Fe?oxides and their carbon matrix composites with different morphologies were prepared by hydrothermal method.The structure,phase and elements have been characterized by scanning electron microscopy,high-resolution transmission electron microscopy,X-ray photoelectron spectroscopy,energy dispersive spectrometer,Raman spectrometer,infrared Fourier infrared spectrum analyzer,X-ray powder diffractometers,and electrochemical performance test is studied by using electrochemical workstation.Through the analysis and induction of experimental data,the influence of hydrothermal process parameters on the structure and electrochemical properties of metal oxides and their composites was studied,and the mechanism was summarized and analyzed.This paper mainly includes the following contents:?1?Manganese dioxide with different morphologies,such as nanosandwich,nanowire,microrod and microflower,was successfully prepared by using potassium permanganate and manganese sulfate as reactants and controlling the reaction conditions.According to the analysis and comparison of the experimental results,the microflower-like manganese dioxide has the largest specific surface area?57.6485 m²/g? and specific capacitance?184.8 F/g?,and the capacitance retention rate is 85%after 10,000 charge and discharge cycles.?2?MnO₂/carbon nanofiber?CNFs? composites were successfully synthesized by hydrothermal method.The effects of hydrothermal reaction temperature and potassium permanganate concentration on the composites were investigated.The electrochemical test results determined the synthesis conditions of the composite with the best electrochemical performance:the reaction temperature was 80?,and the potassium permanganate concentration was 25 mmol/L.The composite material synthesized under this condition has the highest specific capacitance?245.33 F/g?,and the capacitance retention rate is 86.7% after 5000 charge and discharge cycles.?3?MnO₂/reduced graphene oxide?MnO₂/rGO?composites were successfully synthesized by one-step hydrothermal method with GO as the substrate and potassium permanganate as the oxidant.The highest specific capacitance reached 255 F/g,with good cyclic stability.After 10,000 charge and discharge cycles,the capacitance retention rate was 84.5%.?4?Fe₂O₃ and rGO composites were prepared by hydrothermal method and subsequent heat treatment with ferrous chloride and urea.The electrochemical test results showed that the electrochemical performance of Fe₂O₃ was improved to some extent by the existence of rGO.