A Research Of Nano Iron Based Material In The Negative Electrode Of Supercapacitor

With the development of economy,the problem of energy and environment has become the focus of people’s discussion.We are eager to find green renewable energy to replace fossil energy for the shortage of it and the aggravation of environmental problems.Wind energy,water energy,tidal energy,geothermal energy and solar energy which are green renewable resources,have been serving all over the world.The use of these sources will neither pollute the environment nor be depleted,but how to store these energy is a key issue.Traditional energy storage devices,such as lithium-ion batteries and lead-acid batteries,have irreplaceable positions in the field of current energy storage devices.However,we are still unable to get rid of the disadvantages of low power density,high risk coefficient and high cost.Because of its long cycle life,high power density,fast charging speed and so on,supercapacitor has been widely concerned by researchers and energy storage device manufacturers worldwide.The most important thing in the study of supercapacitor is the development and optimization of the electrode materials.In this paper,hydrothermal synthesis method is used to prepare the composite materials of the Fe and transition metal elements,such as Ni,Co and Mn.Then,the composite material was coated with carbon,and the negative electrode material with good performance were synthesized.The contents of this paper are as follows:(1)Preparation of graphene oxide.To prepare iron composite material based on the graphene,it is necessary to prepare graphene oxide first.In this paper,the preparation of graphene oxide was improved by improved Hummers method.In order to prevent the agglomeration between the graphene sheets to affect the properties of the composite,the prepared solution of graphene oxide is made.(2)The preparation of rGO@FeCo@C and rGO@FeNi@C composites.By hydrothermal synthesis,FeCo and FeNi composites were grown in the graphene which was reduced at high temperature.Then carbon coating is used to treat the composite by tube furnace.The composite was characterized by scanning electron microscope(SEM)and the electrochemical performance was tested by an electrochemical workstation.(3)The preparation and optimization of rGO@FeMn@C composites.These composites were characterized by SEM and analyzed by the X diffraction instrument.According to the results of electrochemical testing,the composite was compared and optimized from the carbon coating and the proportion of FeMn.The rGO@FeMn@C composites prepared in this paper have complete morphology and large specific surface area.The energy density is up to 194mAh/g and the cycle life is longer.It is not attenuated in the 100 cycles and still holds 97%of the initial energy density after the 200 cycles.