Method for directly preparing graphene-manganese dioxide composite material from graphite and application of graphene-manganese dioxide composite material

Abstract

The invention relates to a method for directly preparing a graphene-manganese dioxide composite material from graphite and an application of the graphene-manganese dioxide composite material. The graphene-manganese dioxide composite material is directly prepared from natural flake graphite by an intercalation-stripping method, and is quickly gathered to form a three-dimensional porous structure by adjusting the pH value; and the graphene-manganese dioxide composite material is finally applied to an electrode of an all-solid supercapacitor. According to the method, preparation of oxidized graphene is not needed; and meanwhile, time-consuming washing, filtering and subsequent sedimentation or in-situ growth of manganese dioxide particles are not needed, so that the technological process is simplified. The prepared graphene is low in oxidation degree and low in defect level; and the conductivity of the composite material is high and can reach above 1.0*10<4>S / m. The three-dimensional structure is formed by adding an acid for induction, so that the effective specific surface area is significantly improved when the conductivity is not affected. Meanwhile, the prepared all-solid supercapacitor shows outstanding electrochemical properties; the specific capacitance can be up to 66mF / cm<2> (138.8F / g); the maximal energy density is 0.21[mu]Wh / cm<2>; the maximal power density is 141.2[mu]W / cm<2>; meanwhile, the specific capacitance can still be reserved above 90% after 1,000 cycles; and the graphene-manganese dioxide composite material shows good cycling stability.

Description

technical field [0001] The invention relates to the technical field of graphene preparation and application thereof, in particular to the preparation of a graphene-manganese dioxide composite material, the construction of a pH-induced three-dimensional structure and its application in an all-solid-state supercapacitor. Background technique [0002] In recent years, supercapacitors have received increasing attention as a new type of energy storage device. Compared with batteries, supercapacitors have higher power density, faster charging speed, and good cycle stability. According to their energy storage mechanism, supercapacitors can generally be divided into two categories, namely electric double layer capacitors and pseudocapacitors. Electric double layer supercapacitors usually use carbon-based materials, such as activated carbon, carbon nanotubes, and graphene, while pseudocapacitive supercapacitors mostly use conductive polymers and transition metal oxides / hydroxides as...

AI Technical Summary

Problems solved by technology

[0005] In the current graphene-manganese dioxide research, there are many composite materials with excellent performance, but in the process of preparing graphene, it is usually necessary to prepare graphene oxide first, and then obtain reduced graphene oxide by chemical reduction or thermal reduction, which requires Time-consuming washing, filtration and subsequent deposition or in-situ growth of manganese dioxide particles

The overall production process is cumbersome and complex, with long cycle time and high cost, and it is difficult to expand the scale to meet the needs of industrial production

In addition, some oxygen-containing functional groups still remain in the reduced graphene oxide, which leads to an increase in the degree of oxidation and defects, resulting in a decrease in electrical conductivity, which affects its electrochemical performance.

Images