Research On Preparation And Properties Of Iron Oxide/Multilayer Graphene Composites

Supercapacitors are a new type of energy storage device with superior power density,high cycle life and low chemical contamination.Iron oxide has a low redox potential and is the most important anode material.The study of preparing iron oxide nanoparticles on the surface of graphene by simple chemical reaction and controlling its morphology has important research significance for improving the performance of iron oxide electrode.The main research contents of this thesis are as follows:A multilayer graphene/?-Fe2O3 composite was prepared by one-step water bath agitation.In the experiment,iron powder was used as the iron source,and magnetic ?-Fe2O3 was prepared by slow oxidation.Different sizes of ?-Fe2O3 were prepared by controlling the reaction time.In addition,spherical and cubic morphologies of ?-Fe2O3 were prepared by process control.The spherical granular ?-Fe2O3 has a high specific capacity of 415 F g-1 at current density of 2 A g-1,and the specific capacitance of the cubic ?-Fe2O3 is 150 F g-1.A multilayer graphene/?-Fe2O3 composite was prepared by one-step water bath agitation.The experiment uses iron powder as the iron source,and uses the rapid oxidation method to prepare the nano-?-Fe2O3 with multi-layer stacked three-dimensional porous structure on the surface of the multilayer graphene.The effects of reaction time,the amount of iron powder added and the amount of dilute nitric acid on the morphology,crystal form,product and electrochemical properties of the composites were investigated.The size of the iron oxide particles and the distribution density of the iron oxide nanoparticles on the graphite sheet can be controlled by controlling the amount of iron powder added and the reaction time.The optimal multilayer graphene/?-Fe2O3 composite prepared has a specific capacity of 975 F g-1 at current density of 2 A g-1 and a specific capacitance of 508 F g-1 at current density of 15 A g-1.Use the multilayer graphene/?-Fe2O3 composite prepared by this method as negative electrode material,and CoNi-LDH as the positive electrode material to assemble two-electrode supercapacitor.The assembled supercapacitor has a higher specific capacity and energy density at voltage window of 0-1.6V.The capacitance at a current density of 2 mA cm-2 was 1640 mF cm-2.At a power density of 556 W kg-1,the energy density reached 42.7 Wh kg-1.