CN103594254B - The preparation method of a kind of manganese dioxide/mesoporous carbon nanometer classification combination electrode material - Google Patents

Abstract

The invention discloses a preparation method of a manganese dioxide/mesoporous carbon nanometer graded composite electrode material. The method first uses manganese sulfate and ammonium persulfate as reactants, and prepares sea urchin-like carbon dioxide with a certain hollow structure by a hydrothermal method. Manganese, then use phenolic resin and tetraethyl orthosilicate as the precursors of carbon and silicon dioxide respectively, and F127 as the structure control agent, combine the ordered mesoporous carbon and manganese dioxide through volatilization self-assembly and carbonization, and finally use The sodium hydroxide aqueous solution removes the silicon dioxide nanospheres in the material, and obtains the hierarchically structured manganese dioxide/mesoporous carbon nanocomposite material. When this material is used as a supercapacitor electrode material, its specific capacity is nearly double that of pure manganese dioxide. The test results show that the composite material has the advantages of high conductivity of carbon materials and high specific capacity of manganese dioxide, and improves The rate performance and cycle stability of the material are improved, and the electrochemical performance is excellent.

Description

A kind of preparation method of manganese dioxide/mesoporous carbon nanoscale composite electrode material

technical field

The invention belongs to the field of new energy materials, and relates to a preparation method of a supercapacitor electrode material, in particular to a preparation of a manganese dioxide/mesoporous carbon nanometer graded composite material.

technical background

Supercapacitors, also known as electrochemical capacitors, are a new type of green energy storage element that has attracted widespread attention because of their higher power density than batteries and higher energy density than traditional electric double layer capacitors. Especially in recent years, with the continuous growth of global energy demand and the decrease of fossil fuel reserves, and the environmental pollution caused by the burning of fossil fuels seriously affects the living environment of human beings, so the research and development of clean and renewable energy is becoming more and more important. extremely important. Supercapacitors also have the characteristics of fast charging and discharging, long cycle life, wide operating temperature range, and low environmental pollution, which makes them applicable to hybrid vehicles, portable electronic products, storage backup systems, and large factory facilities as energy storage devices and military equipment. However, existing supercapacitors still suffer from many disadvantages, such as relatively low energy density, high cost, high self-discharge rate, lack of commercialization standards, etc. Electrode materials are the core components of supercapacitors, and the design and development of excellent electrode materials is the key to improving performance.

Ordered mesoporous carbon is a new type of porous carbon material with unique physical and chemical properties. Its ordered mesoporous structure is conducive to the rapid transport of ions and is widely used as electrode materials. Compared with commercial activated carbon materials, ordered mesoporous carbons with large mesoporous and two-dimensional pore structures exhibit excellent capacitive behavior, power output, and high rate capability. However, compared with the two types of electrode materials, metal oxides and conductive polymers, the specific capacity of carbon materials is low. Manganese dioxide has the advantages of low cost, non-toxicity, high theoretical specific capacity, and good stability. It is an ideal electrode material, but its resistance is large. The ordered mesoporous carbon is infiltrated and coated with large-diameter sea urchin-like manganese dioxide, so that the two can be combined to give full play to the synergistic effect between the two different materials, and improve the specific surface area and electrical conductivity of the composite material, thereby optimizing the electrode Electrochemical properties of materials.

Contents of the invention

In view of the above problems, the purpose of the present invention is to propose a method for preparing a manganese dioxide/mesoporous carbon nanoscale composite electrode material, and to study its electrochemical performance as a supercapacitor electrode material.

The idea of the present invention is as follows: prepare hollow sea urchin-like manganese dioxide by hydrothermal method, fully mix it with the precursor phenolic resin of ordered mesoporous carbon and the precursor orthosilicate ethyl ester of silicon dioxide, make The phenolic resin is coated on the surface of manganese dioxide and impregnated into the interior, volatilized and self-assembled at room temperature to solidify the phenolic resin, and then carbonized in a high-temperature tube furnace. Finally, the silica spheres were removed by sodium hydroxide aqueous solution to obtain hierarchical structure manganese dioxide/mesoporous carbon nanocomposites. The composite of mesoporous carbon material and sea urchin-like manganese dioxide is beneficial to improve the specific surface area and conductivity of the material, exert the synergistic effect between the two, and improve the electrochemical performance of the material.

The present invention is achieved through the following technical solutions:

A preparation method of manganese dioxide/mesoporous carbon nanometer graded composite electrode material, comprising the steps of:

(1) Add 0.5~1.0g manganese sulfate monohydrate and 0.6~1.5g ammonium persulfate to 45mL deionized water successively, stir for 40~80min, pour into the reaction kettle and put the reaction kettle into the oven, at 80~120℃ Keep it in an oven for 8 to 12 hours, wash and dry the black precipitate obtained by the reaction with deionized water and absolute ethanol, and obtain sea urchin-like manganese dioxide with a hollow structure;

(2) Dissolve 0.06-0.5g of 0.2M hydrochloric acid solution and 0.05-0.5g of Pluronic F127 in 3-8g of absolute ethanol, stir well and add 0.1-1.0g of tetraethyl orthosilicate and 0.3-2.5g of mass fraction 20 % phenolic resin ethanol solution, continue to stir for 15 to 30 minutes to obtain a mixed solution;

Described mass fraction is that ethanol is solvent in the phenolic resin ethanol solution of 20%;

(3) Add 0.1 g of the sea urchin-like manganese dioxide obtained in step (1) into the mixed solution in step (2), stir and ultrasonically 2-4 hours, then let it stand for 3-6 hours to volatilize and self-assemble, and put it in 80- 120 ℃ oven insulation for 16 ~ 30h to obtain the composite;

(4) Put the compound obtained in step (3) into a high-temperature tube furnace, keep it warm at 800-1000°C for 1-4 hours under the protection of nitrogen, and carbonize the phenolic resin in the compound to obtain a black product;

(5) Grind the black product obtained in step (4), put it into an aqueous solution of sodium hydroxide with a concentration of 1-2M and stir for 16-30 hours, remove the silica balls in it, and wash it with a large amount of deionized water and absolute ethanol until Neutralize and dry to obtain the manganese dioxide/mesoporous carbon nanometer graded composite electrode material.

In the manganese dioxide/mesoporous carbon nanometer graded composite electrode material, the manganese dioxide has a diameter of 1-5 μm and a surface needle length of 500 nm-1 μm.

The manganese dioxide/mesoporous carbon nanocomposite material with hierarchical structure is a structure in which ordered mesoporous carbon permeates and coats sea urchin-like manganese dioxide, and the surface morphology of the composite varies with the change of carbon content.

The manganese dioxide/mesoporous carbon nanometer graded composite electrode material is applied in a supercapacitor, and its specific capacity is 0.8-1 times higher than that of pure manganese dioxide, and has excellent electrochemical performance.

Beneficial effects of the present invention:

It can be seen from the above technical scheme and implementation method that the present invention uses the prepared hollow sea urchin-like manganese dioxide as a carrier, coats and penetrates the phenolic resin into its interior, and removes the silica balls in the material after curing and carbonization to obtain a hierarchical structure manganese dioxide/mesoporous carbon nanocomposites. The combination of mesoporous carbon material and manganese dioxide greatly increases the specific surface area and pore capacity of the material, and improves the electric double layer capacitance of the material. Ordered mesoporous carbon is coated on the surface of manganese dioxide and runs through its internal structure, which is beneficial to the transmission and diffusion of electrolyte ions in the material, reduces the transmission path of electrolyte ions during charging and discharging, and greatly improves The electrochemical utilization of manganese dioxide is improved, thus improving the electrochemical performance of the composite. The content of mesoporous carbon in the composite can be controlled by adjusting the amount of phenolic resin and tetraethyl orthosilicate, thereby affecting the structure and electrochemical performance of the composite. The preparation method of the invention has simple process, cheap and easy-to-obtain raw materials, and is easy for large-scale production. The electrode material made of manganese dioxide/mesoporous carbon nanoscale composite material exhibits excellent electrochemical properties such as high specific capacity, high rate performance and good cycle stability, and can be used in supercapacitors.

Description of drawings

Fig. 1 is the scanning electron micrograph of embodiment 1 product;

Fig. 2 is the scanning electron micrograph of embodiment 2 product;

Fig. 3 is the specific surface area and the pore size distribution of the manganese dioxide/mesoporous carbon nanocomposite prepared in embodiment 1;

Fig. 4 is the galvanostatic charge-discharge curve of the manganese dioxide/mesoporous carbon graded composite material prepared in Examples 1 and 2 at a current density of 1Ag ^-1 ;

Fig. 5 is the cyclic voltammetry curve of the manganese dioxide/mesoporous carbon nanocomposite prepared in embodiment 1;

6 is the cycle stability curve of the manganese dioxide/mesoporous carbon nanocomposite prepared in Example 1.

detailed description

The following are examples of the present invention, providing detailed implementation and specific operation process, the purpose of which is only to better understand the content of the present invention. The scope of protection of the invention is therefore not restricted by the examples given.

Example 1

Add 0.6761g manganese sulfate monohydrate and 0.9128g ammonium persulfate into 45mL deionized water successively, stir for 60min, pour into the reaction kettle and put the reaction kettle into the oven, keep it in the oven at 100°C for 10h, and remove the black precipitate obtained from the reaction Wash and dry with deionized water and absolute ethanol to obtain sea urchin-like manganese dioxide with a hollow structure.

Dissolve 0.0625g of 0.2M hydrochloric acid solution and 0.1000g of F127 in 4g of absolute ethanol, stir well and then add 0.1300g of tetraethyl orthosilicate and 0.3125g of phenolic resin ethanol solution with a mass fraction of 20%, and continue stirring for 20min to obtain a mixed solution.

Add 0.1000 g of the above-prepared sea urchin-like manganese dioxide into the above-mentioned mixed solution, ultrasonically stir it for 3 hours, let it stand at room temperature to volatilize and self-assemble for 5 hours, put it in an oven at 100° C., and keep it warm for 24 hours to obtain a composite. The obtained compound was put into a high-temperature tube furnace and kept at 900° C. for 2 h under the protection of nitrogen to obtain a black product. Grind the obtained black product into powder, put it into a 2M aqueous sodium hydroxide solution and stir for 24 hours, remove the silica balls, wash with deionized water and absolute ethanol until neutral, and dry to obtain Manganese/mesoporous carbon nanoscale composite electrode material, Figure 1 is its electron microscope photo, and its specific surface area and pore size distribution are shown in Figure 3.

Example 2

Add 0.6761g manganese sulfate monohydrate and 0.9128g ammonium persulfate into 45mL deionized water successively, stir for 60min, pour into the reaction kettle and put the reaction kettle into the oven, keep it in the oven at 100°C for 10h, and remove the black precipitate obtained from the reaction Wash and dry with deionized water and absolute ethanol to obtain sea urchin-like manganese dioxide with a hollow structure.

Dissolve 0.25g of 0.2M hydrochloric acid solution and 0.4000g of F127 in 6g of absolute ethanol, stir well and then add 0.5200g of tetraethyl orthosilicate and 1.25g of phenolic resin ethanol solution with a mass fraction of 20%, and continue to stir for 20min to obtain a mixed solution.

Add 0.1000 g of the above-prepared sea urchin-like manganese dioxide into the above-mentioned mixed solution, ultrasonically stir it for 3 hours, let it stand at room temperature to volatilize and self-assemble for 5 hours, put it in an oven at 100° C., and keep it warm for 24 hours to obtain a composite. The obtained compound was put into a high-temperature tube furnace and kept at 900° C. for 2 h under the protection of nitrogen to obtain a black product. Grind the obtained black product into powder, put it into a 2M aqueous sodium hydroxide solution and stir for 24 hours, remove the silica balls, wash with deionized water and absolute ethanol until neutral, and dry to obtain Manganese/mesoporous carbon nanoscale composite electrode material, Figure 2 is its electron microscope photo.

Example 3 Characterization of manganese dioxide/mesoporous carbon nanoscale composites

Field emission electron microscope (HITACHIS4800) and nitrogen adsorption-desorption (MicromeriticsASAP2020) analyzer were used to perform surface morphology and chemical structure characterization analysis on the manganese dioxide/mesoporous carbon nanocomposites prepared in the above-mentioned examples 1 and 2. , the results are shown in Figures 1, 2, 3 and Table 1.

Electrochemical Characterization of Example 4 Manganese Dioxide/Mesoporous Carbon Nanoscale Composite

Mix the manganese dioxide/mesoporous carbon nanometer graded composite electrode material prepared in Example 1 and Example 2, carbon black and polytetrafluoroethylene in a mass ratio of 8:1:1, add a small amount of dehydrated alcohol, mix, Stir to make a thick slurry. A 2×1 cm ² carbon paper was used as a current collector, and the slurry prepared above was uniformly coated on the carbon paper with an area of about 1×1 cm ² , and then placed in an oven at 70°C for 12 hours to keep warm. The composite material electrode sheet prepared above was used as the working electrode, the platinum sheet was used as the counter electrode, the saturated calomel electrode was used as the reference electrode, and 1M sodium sulfate aqueous solution was used as the electrolyte to assemble a three-electrode test system to test the electrochemical performance. The electrochemical performance test was carried out on the electrochemical workstation PGSTAT302N, and the test voltage range was -0.1～0.9V. The electrode materials prepared in Example 1 and Example 2 were subjected to constant current charge and discharge tests at 1Ag ⁻¹ , and the results are shown in FIG. 4 . The electrode material prepared in Example 1 was tested by cyclic voltammetry, and the results are shown in FIG. 5 . The electrode material prepared in Example 1 was tested for cycle stability, and the results are shown in FIG. 6 .

The physical properties of the product in embodiment 1 and embodiment 2 are as shown in table 1.

Table 1

According to the charge-discharge curve, the specific capacitance values of the electrode materials prepared in Examples 1 and 2 at different current densities can be calculated.

C=(IΔt)/(mΔV)

In the formula, C—the specific capacity of the active substance, Fg ^-1

I—constant current value, A

Δt—discharge time, s

m—mass of active material on the electrode sheet, g

ΔV—discharge voltage range, V

Table 2 shows the specific capacities (Fg ^-1 ) of the composite electrode materials in Examples 1 and 2 at different current densities calculated using the above formula and the charge-discharge curves in Fig. 4 .

Table 2

Claims (3)

1. a preparation method for manganese dioxide/mesoporous carbon nanometer classification combination electrode material, is characterized in that, comprise the steps:

(1) 0.5 ~ 1.0g Manganous sulfate monohydrate and 0.6 ~ 1.5g ammonium persulfate are successively joined in 45mL deionized water, stir 40 ~ 80min, pour reactor into and reactor is put into baking oven, 8 ~ 12h is kept in the baking oven of 80 ~ 120 DEG C, by the black precipitate deionized water that is obtained by reacting and absolute ethanol washing, dry, obtain the sea urchin shape manganese dioxide with hollow-core construction;

(2) be that the hydrochloric acid solution of 0.2M and 0.05 ~ 0.5g pluronic F127 are dissolved in 3 ~ 8g absolute ethyl alcohol by 0.06 ~ 0.5g concentration, add the ethanolic solution of the phenolic resins of 0.1 ~ 1.0g tetraethoxysilane and 0.3 ~ 2.5g mass fraction 20% after stirring respectively, continue stirring 15 ~ 30min and obtain mixed solution;

Described mass fraction is that in the ethanolic solution of the phenolic resins of 20%, ethanol is solvent;

(3) sea urchin shape manganese dioxide 0.1g step (1) obtained joins in the mixed solution of step (2), stir ultrasonic 2 ~ 4h, then left standstill volatilization self assembly 3 ~ 6h, the baking oven insulation 16 ~ 30h putting into 80 ~ 120 DEG C obtains compound;

(4) compound that step (3) obtains is put into high temperature process furnances, 800 ~ 1000 DEG C of insulation 1 ~ 4h, by the phenolic resin carbonized in compound, obtain black product under nitrogen protection;

(5) black product grinding step (4) obtained, the sodium hydrate aqueous solution putting into concentration 1 ~ 2M stirs 16 ~ 30h, removing silica spheres wherein, neutrality is washed till with a large amount of deionized water and absolute ethyl alcohol, dry, obtain manganese dioxide/mesoporous carbon nanometer classification combination electrode material.

2. preparation method according to claim 1, is characterized in that, in described manganese dioxide/mesoporous carbon nanometer classification combination electrode material, the diameter of manganese dioxide is 1 ~ 5 μm, and surperficial acupuncture length is 500nm ~ 1 μm.

3. preparation method according to claim 1, is characterized in that, described manganese dioxide/mesoporous carbon nanometer classification combination electrode material is applied in ultracapacitor, and its specific capacity exceeds 0.8 ~ 1 times than pure manganese dioxide.