Metal ion-doped flower-like MnO2 nanosheets for supercapacitor and preparation method of metal ion-doped flower-like MnO2 nanosheets

Abstract

The invention discloses metal ion-doped flower-like MnO2 nanosheets for a supercapacitor and a preparation method of the metal ion-doped flower-like MnO2 nanosheets. By a chemical precipitation method, preparation of nanosheet-self-assembled flower-like MnO2 is guided by doping metal ions, and the sheet thickness of the nanosheet-self-assembled flower-like MnO2 is 3-5nm; the preparation method comprises the following steps: putting a mixed aqueous solution of manganese sulfate and ammonium persulfate in a concentration ratio of 1: 1 into an ultrasonic constant-temperature water bath environment, dropwise adding a metal salt solution with the concentration of 0.001-0.2mol/L into the mixed solution at a uniform speed, and then continuing reacting for 0.5-3h. The preparation method is simple in preparation process and low in cost; a flower-like structure obtained by self-assembling nanosheets significantly increase the specific surface area of an electrode material and facilitates diffusion of electrolyte ions in the bulk phase of the electrode material, so that the flower-like structure has excellent electrochemical properties. When the scanning rate is 50mV/s, the measured specific capacitance can reach 303.6F/g and the measured impedance is 4.2 omega.

Description

technical field [0001] The invention relates to the field of preparation of supercapacitor electrode materials, in particular to a metal ion-doped flower-shaped MnO for supercapacitors 2 Nanosheets and methods for their preparation. Background technique [0002] As a transition metal oxide, manganese dioxide has a variable oxidation state, and has the advantages of low price, environmental friendliness, and wide sources. At the same time, its excellent theoretical specific capacitance characteristics make it a great development as an electrode material for supercapacitors. potential. However, when manganese dioxide is used as an electrode material, its poor conductivity and electrode stability lead to its actual specific capacitance value being much lower than its theoretical value. Improving the conductivity and electrode stability has become an urgent problem to be solved. With the development of nanomaterials and doping technology, special nanostructures or doped metal...

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Problems solved by technology

However, the preparation process of these two methods is complicated, it is difficult to effectively control the preparation process, and some drugs are expensive, so it is difficult to carry out industrial promotion

[0003] The patent document whose publication number is CN 104310486 A discloses a method for synthesizing single-layer manganese dioxide nanosheets in one step. The method utilizes alkyl The sulfate surfactant is hydrolyzed to generate the corresponding alcohol in situ reduction of permanganate to generate manganese dioxide, but the preparation process of this method is simple, and the ultrathin nanosheet structure can be obtained and has good redox characteristics, but the alkane used in this method The base surfactant is toxic, and the acid solutions used are all strong acids, which cause serious damage to the environment. This method is not conducive to commercial promotion

[0004] The patent document whose publication number is CN 103641174 A discloses a kind of nano flake MnO 2 -The preparation method of graphene composite material, this method is: manganese nitrate solution carries out oxidation-reduction reaction in hydrogen peroxide and alkali mixed solution and makes powder; Disperses described powder in ammonium persulfate solution treatment, then disperses into organic solvent , to obtain nanosheet MnO 2 solution; the nanosheet MnO 2 After the solution is diluted, it is mixed with the dispersion of graphene powder and ultrasonically treated to obtain nano-sheet MnO 2 -Graphene composite material, its specific capacitance value can reach 578F / g, but the preparation process of this method is complicated, and MnO 2 The physical combination with graphene is not conducive to the improvement of electrode stability

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