Hydrothermal Synthesis Of Manganese Oxide Nano Materials And Their Electrochemical Properties

With the development of economy and population in modern society,people's demand for energy have begun to increase,and energy shortage is becoming a major concern of scientists.Supercapacitors?SC?,also known as electrochemical capacitors,which have been paid more and more attention by scientists due to its excellent energy density and double rate,good circulation life and safe operation.As an important part of SC,electrode material has a direct influence on the application prospect of SC.has good application prospect as electrode material for SC due to natural abundance,low cost,high theoretical specific capacitor.In this work,Nano-manganese oxides with different morphology were prepared by hydrothermal method.The morphologies and crystal structures had been investigated by X-ray diffraction?XRD?,scanning electron microscopy?FESEM?and transmission electron microscopy?TEM?respectively.The effect of surface morphology and other microscopic characteristics on electrochemical properties was discussed according to the test results of electrochemical workstation.The main contents and conclusions are listed as follow:?1?Through adjusting the concentration of oxidant and the reaction time,one-dimensional?1D?nanobelt and nanorod of?-MnO₂ and hollow nanourchin-like MnO₂ were controlled.Compared with the nanobelt and nanorod of?-MnO₂,the morphology of the hollow structure can provide a larger specific surface area and more electrical activity bits.The ordered and uniform nanowires can facilitate the diffusion path of the short charged particles,which is beneficial to pseudocapacitive reaction.Its specific capacitance value is 211.1 F g^-1,and after 1000 cycles of charging and discharging,the residual capacity reaches 93.6%.?2?Fe-doped MnO₂ were synthesized via a simple hydrothermal process by using FeCl₃ as supplier of Fe³⁺.The morphology of MnO₂ nanoflower transformed into nanoneedle because Fe³⁺existed,but not changed the original crystal structure of MnO₂.Fe³⁺were distributed evenly on the outside of the nanometer needle,effectively improving the conductivity of electrode material,reducing the internal impedance of the material and improving the electrochemical performance.The specific capacitance of Fe-doped MnO₂ is 257.6 F g^-1,and after 1000 cycles of charging and discharging,the residual capacity reaches 90.4%.?3?The rod-like MnCo₂O₄ nanoarray were successfully synthesized by using Co?NO₃?₂·6H₂O as additive.The mesoporous properties of materials effectively shorten the charge diffusion path,and provide more electrical active sites and bigger surface area.The efficient charge storage mechanism makes it have better electrochemical properties.The specific capacitance of MnCo₂O₄ nanoarray is 662.5 F g^-1,testing at 1 A g^-1 current density in KOH alkaline electrolyte,and after 3000 cycles of charging and discharging,the residual capacity reaches 94.2%.The rod-like MnCo₂O₄ nanoarray showed excellent electrochemical performance and cyclic stability.