Assembly Of Mn-Al Layered Double Hydroxide And Graphene Electrodes For Supercapccitors

Supercapacitor is a new type of energy storage device. It has a long cycle life and can charge-discharge with high current. It has a wide range of application in market.It is widely researched in the field of new energy. We mainly do the research of the electrode material of supercapacitor. The commonly used electrode materials are carbon materials, transition metal oxide/hydroxide and conductive polymer. Researchers usually assemble layered double hydroxide and graphene electrodes to improve the utilization rate of pseudocapacitance electrode material and prepare electrode materials with high specific capacity. Layered double hydroxide is a kind of electrode materials with huge potential, but low electrical conductivity of layered double hydroxide limit the migration of electrolyte ions and electrons, which affect their electrochemical performance. Carbon with nano structure can be used as an active component or support to improve the capacity of the electrode materials.Carbon nanostructures including zero-dimensional carbon black,one-dimensional carbon nanotubes and two-dimensional graphene. Graphene is famous for its advantages of big specific surface area, good conductivity.It is commonly used on super capacitor electrode.This paper uses the two-dimensional graphene and manganese aluminum composite layered double hydroxide to recombine as super capacitor electrode materials.We first adopts coprecipitation method to get layered double hydroxide of different anion and different ratio of manganese and aluminum, the microstructure of material is spherical morphology. With the improvement of the ratio of manganese and aluminum, a small amount of flake and dendritic structure will appear. As the electrochemical performance test, when the ratio of manganese salt and aluminum salt is 1:1, and the interlayer anion is chloride ion, specific capacity of material can reach about 200 F/g. In the second part, we prepared the graphene oxide and graphene. We adopt Hummers method which is commonly to get graphene oxide with good layer structure.Then we use three different methods to get graphene, they are thermal reduction, reduction of glucose and sodium citrate reduction method. As glucose reduction method can get graphene with good layer structure, and it is easily prepared, so we adopt this method in the preparation of composite materials for the follow-up work. The third part is mainly about the combination of graphene and layered double hydroxide. We adopt three methods which are coprecipitation method, hydrothermal method and solvent thermal synthesis methods to get the composite. Experiments show that the solvent thermal synthesis method can significantly increase the specific capacity of layered double hydroxide, specific capacity of materials is about 260 F/g.