Preparation And Performance Study Of NiO And Graphene/NiO Composites As Supercapacitor Material

Supercapacitor is a new kind of energy storage device, it has been thought as the most important energy storage device because of high power density, excellent cycle ability and environment protection. Supercapacitors have been used in industrial UPS power supply, electric vehicle, aerospace and so on. In this paper, the author investigated the research of supercapacitor and selected NiO as research object. The author tried to improve the specific capacitance of NiO and to improve the energy density. On one side, we try to control the shape of NiO to synthesis stable NiO with large surface to improve the specific capacitance and cyclic ablity, on the other side, we try to synthesis a new two-dimension structure composite to improve electrical conductivity, wetting quality, then improve the specific capacitance, rate ability and cyclic ability.This paper has mainly been performed through the following aspects:(1) Hydro-thermal method was used to synthesize porous NiO nanosheets, through adjusting the calcined temperature to tune the specific surface and pore diameter. The material was tested with XRD, SEM and TEM etc. And we try to find the connection between structure and capacitance. The specific surface area was shown to be the critical factor to capacitance of the material.(2) Co-precipitation method was used to synthesize mono-graphene/NiO nanocomposite, in which graphene conduct as conductive matrix and NiO with a diameter of3-5nm were grown on the two sides of graphene. The two-dimension structure can prevent the aggregation of nanomaterials, enlarge specific surface area and improve wetting ability of the composite. The test results reflect that the composite with novel structure shows high capacity and excellent cyclic ability, the specific capacitance is528F/g at current density of200mA/g and the capacity retention is98.3%after1000cycles. (3) Hydro-thermal method was applied on synthesizing monolayer graphene/NiO. The material was tested by SEM, TEM, XRD and so on to characterize the structure. The material show better electrochemical performance by CHI660C, with specific capacity of430F/g at current density of200mA/g and342F/g at current density of1A/g.