CN102891014B - Graphene electrodes active substance and method for making thereof and electrode material and electrode slice and application - Google Patents

Abstract

The invention provides a graphene electrode active material and a preparation method thereof, a supercapacitor electrode material, an electrode sheet and an application thereof. The method for preparing the graphene electrode active material comprises: dispersing graphite oxide powder in deionized water to obtain a dispersion, and After the dispersion liquid is contacted with the acid, solid-liquid separation is carried out to obtain a solid precipitate, and the solid precipitate is dried and ground to obtain an acid-precipitated graphite oxide powder; the acid-precipitated graphite oxide powder is in an inert gas atmosphere at a temperature of 600 Heat treatment at -1200°C for 1-60 seconds. The graphene electrode active material according to the invention has the advantages of simple preparation method, easy operation, low equivalent series resistance, high specific capacitance, good cycle performance and the like.

Description

Graphene electrode active material and its preparation method, electrode material, electrode sheet and application

technical field

The invention relates to a graphene electrode active material, a preparation method thereof, an electrode material, an electrode sheet and an application thereof.

Background technique

On a global scale, energy, as one of the pillar industries of modern human civilization, has been paid more and more attention by people. However, various environmental issues accompanying energy production, storage and transmission have also become the most concerned hotspots in the world. In response to these problems, in the 1980s, western developed countries began to research and develop clean and efficient new power sources. Supercapacitor energy storage system is a "green technology" that unifies energy and environmental protection. It is a positive and feasible strategy for protecting the earth's environment, preventing air pollution and greenhouse effect, and thus has received widespread attention from all countries.

Supercapacitors (supercapacitors), also known as electrochemical capacitors (electro-chemical capacitors, ECs), as a new type of chemical power supply, have a long service life (10 ⁵ cycles), high specific power (1500W/kg), and fast charging ( It can be several seconds), low temperature performance (minimum working temperature -50°C), high current discharge performance, large energy storage, higher power density than batteries, higher energy density than traditional capacitors, not only compatible with batteries It can be used together to provide peak power for electric vehicles, etc., and can even provide power for electric tools or electric vehicles alone, so as to reduce the negative impact on ecology based on the energy provided by the combustion of fossil resources. Moreover, it is light in weight, maintenance-free, low in pollution, cheap in price, and excellent in performance, and is known as a new type of green energy. Therefore, supercapacitors are likely to develop into an efficient and practical energy storage device in the future, so they have very broad application prospects in the fields of transportation, energy, communications, power electronics, military industry and national defense, and industrial production.

The quality of electrode materials is the decisive factor for the performance of supercapacitors, and people have been developing electrode materials with higher energy density and higher power density. In the prior art, electrode materials used for supercapacitors can be divided into the following three categories: noble metal oxides, conductive polymers, and carbon-based electrode materials. Among them, the limited resources and high price of precious metals, and the poor cycle stability of conductive polymers limit their applications. Carbon electrode materials mainly include: activated carbon powder, activated carbon fiber, carbon aerogel, carbon nanotubes, etc. However, although porous carbon materials can obtain relatively high specific capacitance, their electrical conductivity is low, and their low specific power limits their application as supercapacitors. Although carbon nanotubes have superior electrical conductivity, their high contact resistance, low specific capacity, and high cost also limit their applications. Graphene material, as a two-dimensional material that has received wide attention in recent years, has a large specific surface area, excellent electrical conductivity, low cost and simple manufacturing process, and is an excellent choice as an electrode material for supercapacitors.

However, in the prior art for preparing graphene, the specific energy density of the obtained graphene material is not high enough. In order to prepare a supercapacitor with a higher specific energy density, it is necessary to prepare a graphene electrode material with a higher specific capacity.

Contents of the invention

The object of the present invention is to provide a kind of equivalent series resistance with low, high specific capacitance, good cycle performance, low cost graphene electrode active material and preparation method thereof, and supercapacitor electrode material comprising the graphene electrode active material and electrodes.

The inventors of the present invention have found through research that the graphite oxide powder is dispersed in deionized water to obtain a dispersion liquid, the dispersion liquid is contacted with acid and precipitated to obtain a solid precipitate through solid-liquid separation, and the solid precipitate is dried and ground to obtain the acid Precipitated graphite oxide powder; the precipitated graphite oxide powder is heat-treated at a temperature of 600-1200° C. for 1-60 seconds under an inert gas atmosphere to obtain a product with low equivalent series resistance and high specific capacitance. Graphene electrode active material with good cycle performance.

That is, the present invention provides a kind of preparation method of graphene electrode active material, it is characterized in that, the method comprises the following steps:

1) Disperse the graphite oxide powder in deionized water to obtain a dispersion liquid, conduct solid-liquid separation after the dispersion liquid is contacted and precipitated with an acid to obtain a solid precipitate, dry and grind the solid precipitate to obtain an acid-precipitated graphite oxide powder;

2) Heat-treat the acid-precipitated graphite oxide powder obtained in step 1) at a temperature of 600-1200° C. for 1-60 seconds in an inert gas atmosphere.

The present invention also provides a graphene electrode active material, wherein the graphene electrode active material is prepared by the above method.

The present invention further provides an electrode material for a supercapacitor, which contains a binder, wherein the electrode material for a supercapacitor also contains the above-mentioned graphene electrode active material.

The present invention further provides an electrode sheet for a supercapacitor, which includes a current collector and an electrode material loaded on the current collector, wherein the electrode material is the above-mentioned electrode material for a supercapacitor.

The present invention further provides an application of the above-mentioned graphene electrode active material in a supercapacitor.

The graphene electrode active material obtained by the method of the invention has the advantages of low equivalent series resistance, high specific capacitance, good cycle performance and low cost.

Description of drawings

Fig. 1 is the scanning electron microscope picture of the graphene electrode active material prepared in embodiment 1;

Fig. 2 is the graphene electrode active material prepared in embodiment 1, the hydrochloric acid precipitated graphite oxide powder, the infrared spectrum of preparing graphene electrode active material and raw graphite in comparative example 1;

Fig. 3 is the cyclic voltammetry curve of the graphene electrode active material prepared in embodiment 1;

Fig. 4 is the graphene electrode active material prepared in embodiment 1 and the cycle stability contrast figure of the electrode active material prepared in comparative example 1-3, wherein, charge and discharge current density is 1A/g;

5 is a scanning electron microscope picture of the graphene electrode active material prepared in Comparative Example 1.

detailed description

The invention provides a kind of preparation method of graphene electrode active material, it is characterized in that, the method comprises the following steps:

1) Disperse the graphite oxide powder in deionized water to obtain a dispersion liquid, conduct solid-liquid separation after the dispersion liquid is contacted and precipitated with an acid to obtain a solid precipitate, dry and grind the solid precipitate to obtain an acid-precipitated graphite oxide powder;

2) Heat-treat the acid-precipitated graphite oxide powder obtained in step 1) at a temperature of 600-1200° C. for 1-60 seconds in an inert gas atmosphere.

According to the preparation method of the graphene electrode active material of the present invention, preferably, the concentration of graphite oxide powder in the dispersion liquid in step 1) is 0.05-0.25% by weight; more preferably step 1) the concentration of graphite oxide powder in the dispersion liquid The concentration is 0.09-0.2% by weight.

According to the preparation method of the graphene electrode active material of the present invention, the method for dispersing the graphite oxide powder in deionized water can adopt various methods known in the art. For example, after adding graphite oxide powder into deionized water, ultrasonic method is used to disperse. The ultrasonic conditions can adopt various conditions known in the art, for example, ultrasonic at 20-80° C. for 10-100 minutes.

According to the preparation method of graphene electrode active material of the present invention, in order to make the dispersion liquid and acid contact precipitation, acid and the graphite oxide powder in the dispersion liquid can more fully contact, preferred step 1) in the graphite oxide powder in the dispersion liquid The average particle size is 5-600 microns; more preferably the average particle size is 10-500 microns.

According to the preparation method of the graphene electrode active material of the present invention, the amount of the acid can be selected according to the amount of graphite oxide powder in the dispersion. Preferably, the amount of acid described in step 2) is 0.05-0.8 mole relative to each gram of graphite oxide powder described in step 1); more preferably relative to each gram of graphite oxide powder described in step 1), step 2 ) said acid is used in an amount of 0.07-0.7 moles.

According to the preparation method of the graphene electrode active material of the present invention, the acid may be various acids known in the art. Preferably, the acid is one or more of hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, hydrobromic acid, hydroiodic acid and acetic acid. The concentration of the hydrochloric acid, hydrobromic acid and hydroiodic acid can be 1-40% by weight, preferably 10-37% by weight; the concentration of the sulfuric acid and phosphoric acid can be 5-98% by weight, preferably 10-50% by weight ; The nitric acid concentration is 5-67% by weight, preferably 10-50% by weight; the acetic acid concentration is 10-100% by weight, preferably 50-100% by weight.

According to the preparation method of the graphene electrode active material of the present invention, the temperature for contacting and precipitating the dispersion liquid with the acid can be changed in a wide range. Preferably, the temperature for contacting and precipitating the dispersion liquid with an acid is 0-100°C; more preferably, the temperature for contacting and precipitating the dispersion liquid with an acid is 5-80°C.

According to the preparation method of the graphene electrode active material of the present invention, preferably, the time for the dispersion liquid to be contacted with the acid to precipitate is 5-240 minutes; more preferably the time for the dispersion liquid to be contacted with the acid to precipitate is 10-240 minutes. 120 minutes.

According to the preparation method of the graphene electrode active material of the present invention, the method comprises drying and grinding the solid precipitate described in step 1) to obtain acid-precipitated graphite oxide powder. The drying can adopt various methods known in the art, for example, vacuum drying the solid precipitate at 30-120° C. for 2-24 hours. The grinding can adopt various methods known in the art, such as manual grinding, pulverizer grinding, ball milling, vibrating milling and the like.

According to the preparation method of graphene electrode active material of the present invention, it is preferred that the average particle diameter of the graphite oxide powder obtained by the acid precipitation after the above-mentioned grinding is 1-300 microns, and the average particle diameter of the graphite oxide powder of the acid precipitation is more preferably 5-300 microns. 150 microns.

According to the preparation method of the graphene electrode active material of the present invention, the method comprises the acid-precipitated graphite oxide powder obtained in step 1), under an inert gas atmosphere, after heat treatment at a temperature of 600-1200 ° C for 1-60 seconds , to obtain the graphene electrode active material of the present invention.

Preferably, the temperature of the heat treatment is 700-1150°C; more preferably, the temperature of the heat treatment is 900-1050°C.

Preferably, the heat treatment time is 5-60 seconds; more preferably 5-30 seconds; further preferably 10-30 seconds. Preferably the above heat treatment is carried out in a tube furnace.

The aforementioned inert gases are known in the art. In the present invention, one or more of inert gases such as nitrogen, argon, and helium are preferred.

According to the preparation method of the graphene electrode active material of the present invention, the graphite oxide may be various graphite oxides known in the art. The present invention preferably adopts the Hummers method described in the document J.Am.Chem.Soc.1958, 80, 1339. to prepare graphite oxide.

The present invention also provides a graphene electrode active material, wherein the graphene electrode active material is prepared by the above method.

According to the graphene electrode active material of the present invention, the graphene electrode active material has a lamellar structure. The surface of the graphene electrode active material has more oxygen-containing functional groups such as carbonyl groups and hydroxyl groups. These oxygen-containing functional groups on the surface of electrode materials can undergo fast and reversible redox reactions during charge and discharge, providing a certain pseudocapacitance, thereby improving the specific capacitance of the entire electrode material.

The present invention further provides an electrode material for a supercapacitor, which contains a binder, wherein the electrode material for a supercapacitor also contains the above-mentioned graphene electrode active material.

The content of the graphene electrode active material can be a conventional content in the art, and in a preferred embodiment, based on the total weight of the graphene electrode active material and binder, the binder's The content may be 0.3-20% by weight, preferably 1-15% by weight; the content of the graphene electrode active material may be 80-99.7% by weight, preferably 85-99% by weight. The binder may be a conventional binder known in the art, such as one or more of polytetrafluoroethylene, polyvinylidene fluoride, butyl rubber and polyacrylate.

The negative electrode material of the present invention may also include a conductive agent, and the conductive agent may be a conventional conductive agent. For example, one or more of acetylene black, carbon black, graphite powder and carbon fiber. The content of the conductive agent can be a conventional content, preferably based on the total weight of the graphene electrode active material, the conductive agent and the binder, and the content of the binder is 1-15% by weight; the graphene The content of the electrode active material is 80-95% by weight; the content of the conductive agent is 0-10% by weight.

The present invention further provides an electrode sheet for a supercapacitor, which includes a current collector and an electrode material loaded on the current collector, wherein the electrode material is the above-mentioned electrode material for a supercapacitor.

The current collector can be a current collector commonly used in supercapacitors, such as metal sheet, metal mesh, metal foil and foamed metal.

The preparation method of the supercapacitor electrode sheet can be carried out as follows. The graphene electrode active material, the binder and the conductive agent are prepared into an electrode slurry with a solvent, and the amount of the solvent added is known to those skilled in the art. Then the prepared electrode slurry is dried, pressed into thin sheets and then pressed onto a current collector to obtain a supercapacitor electrode sheet. The drying temperature may be 80-150° C., and the drying time may be 2-10 hours.

The used solvent of described electrode slurry can be various solvents in the prior art, as can be selected from water, N-methylpyrrolidone (NMP), dimethylformamide (DMF), diethylformamide (DEF) , dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), and one or more of water and alcohols.

The present invention also provides the application of the above-mentioned graphene electrode active material in a supercapacitor.

The present invention is further described through examples below, but the present invention is not limited to the following examples.

In the following examples, a scanning electron microscope (Hitachi S-4800, Hitachi, Japan) was used to test the surface morphology of the graphene electrode active material.

Specific surface area and average pore diameter of the graphene electrode active material obtained in the following examples adopt specific surface area and porosity adsorption instrument (U.S. Mike Instrument Company, model ASAP2020) to measure, and measuring method is BET analysis pore size distribution and porosity analysis method .

Adopt CT2001A in the following examples, LAND battery test system (Wuhan Jinnuo Electronics Co., Ltd.), use the method for constant current charging and discharging to measure the specific capacitance and capacity retention rate of supercapacitor, adopt CHI660d electrochemical workstation (Shanghai Chenhua Instrument Co., Ltd. company), using the AC impedance method to measure the equivalent series resistance of supercapacitors.

Example 1

1) take by weighing 10 grams of natural flake graphite (purchased from Alfa Aisha Company, hereinafter the same, -10 order), and 5 grams of sodium nitrate, under ice bath, join in the 230ml vitriol oil (concentration 98% by weight), Subsequently, 30 g of potassium permanganate was added, the ice bath was removed, and the temperature was raised to 32-38° C., and stirring was kept during this process. When the reactant turns pink, add the reactant to 1.5 liters of deionized water, slowly add hydrogen peroxide with a concentration of 3% by weight until no bubbles are formed, filter to obtain a solid, first use 0.1mol/L dilute hydrochloric acid and then deionized Rinse the solid with water until there is no chloride ion and sulfate ion, dry it under vacuum at 40°C, and grind to obtain graphite oxide powder. The average particle size of the graphite oxide powder is 120 microns.

2) Then 1 gram of the above-mentioned graphite oxide powder was dispersed in 500 grams of deionized water, ultrasonicated (150W water bath) at 20°C for 1 hour, and then 50mL of concentrated HCl (37% by weight) was added at 25°C for 10 minutes Afterwards, the precipitate was obtained by suction filtration, and the precipitate was vacuum-dried and ground at 40° C. to obtain graphite oxide powder precipitated by hydrochloric acid. The hydrochloric acid-precipitated graphite oxide powder had an average particle diameter of 80 micrometers.

3) Put the above-mentioned graphite oxide powder precipitated by hydrochloric acid into a quartz semi-sealed tube under the protection of Ar and put it into a tube furnace preheated to 900° C., take it out after heat treatment for 30 seconds, and obtain a graphene electrode active material. The surface morphology of the graphene electrode active material was measured by a scanning electron microscope, as shown in FIG. 1 , it can be known that the graphene electrode active material has a lamellar microstructure. The graphene electrode active material has a specific surface area of 390 m ² /g and an average pore diameter of 2.5 nm. It can be seen from infrared spectroscopy (see FIG. 2 ) that the surface of the graphene electrode active material has carbonyl groups and hydroxyl groups.

4) Mix the above-mentioned graphene electrode active material with the conductive agent acetylene black and the binder polytetrafluoroethylene in a mass ratio of 80:10:10, stir the above-mentioned mixture to a slurry state under the state of distilled water being added dropwise, and dry After being dried, it is pressed into thin sheets and then pressed on a nickel foam current collector to obtain a supercapacitor electrode sheet. The relevant performance of its supercapacitor was tested in a three-electrode system. In this system, 6mol/L KOH aqueous solution was selected as the electrolyte, the platinum sheet was used as the counter electrode, and the mercury-mercuric oxide electrode was used as the reference electrode.

At a constant current density of 0.1A/g, the specific capacitance is 503F/g, and at a constant current density of 1A/g, the specific capacitance reaches 353F/g, after charging and discharging 5000 times at a constant current density of 1A/g , The capacity retention rate was 87%. Its equivalent series resistance is 0.21 ohms. Fig. 3 is the cyclic voltammetry curve of the graphene powder prepared in embodiment 1.

Comparative example 1

1) Obtain graphite oxide powder by the same method as step 1) in Example 1, and grind the graphite oxide powder to an average particle size of 80 microns.

2) Take 1 g of the above-mentioned graphite oxide powder, put it into a quartz semi-sealed tube under the protection of Ar, put it into a tube furnace preheated to 900° C., take it out after heat treatment for 30 seconds, and obtain a graphene electrode active material. The surface morphology of the graphene electrode active material determined by scanning electron microscopy is a lamellar microstructure (see FIG. 5 ). The graphene electrode active material has a specific surface area of 317 m ² /g and an average pore diameter of 1.9 nm. It can be seen from infrared spectroscopy (see FIG. 2 ) that the surface of the graphene electrode active material has fewer carbonyl groups and hydroxyl groups.

3) Mix the above-mentioned graphene electrode active material with the conductive agent acetylene black and the binder polytetrafluoroethylene in a mass ratio of 80:10:10, stir the above-mentioned mixture to a slurry state under the state of adding distilled water dropwise, and dry After drying, it is pressed into thin sheets and then pressed on the nickel foam collector plate. The relevant performance of its supercapacitor was tested in a three-electrode system. In this system, 6mol/L KOH aqueous solution was selected as the electrolyte, the platinum sheet was used as the counter electrode, and the mercury-mercuric oxide electrode was used as the reference electrode.

At a constant current density of 0.1A/g, the specific capacitance is 203F/g, and at a constant current density of 1A/g, the specific capacitance reaches 147F/g, after charging and discharging 5000 times at a constant current density of 1A/g , The capacity retention rate is 80%. Its equivalent series resistance is 0.33 ohms.

Comparative example 2

The graphene powder was replaced by mesoporous carbon (specific surface area 459m ² /g, average pore diameter 3.3nm) purchased from Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences, and the performance test of supercapacitor was carried out according to the method in Example 1.

At a constant current density of 0.1A/g, the specific capacitance is 98F/g, at a constant current density of 1A/g, the specific capacitance is 96F/g, after charging and discharging 5000 times at a constant current density of 1A/g , The capacity retention rate was 82%. Its equivalent series resistance is 0.62 ohms.

Comparative example 3

Graphene powder is replaced with the gac (specific surface area 1300m ² /g, average aperture is 0.8nm) purchased from Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences to carry out the test of supercapacitor related performance according to the method in embodiment 1,

At a constant current density of 0.1A/g, the specific capacitance is 274F/g, at a constant current density of 1A/g, the specific capacitance is 160F/g, after charging and discharging 5000 times at a constant current density of 1A/g , The capacity retention rate was 62%. Its equivalent series resistance is 0.46 ohms.

Example 2

1) Take by weighing 10 grams of natural flake graphite (325 orders), and 5 grams of sodium nitrate, under ice bath, join in the 230ml vitriol oil (concentration 98% by weight), then add 30 grams of potassium permanganate, remove ice bath, warming up to 32-38°C, keeping stirring during this process. When the reactant turns pink, add the reactant to 1.5 liters of deionized water, slowly add hydrogen peroxide with a concentration of 3% by weight until no bubbles are formed, filter to obtain a solid, first use 0.1mol/L dilute hydrochloric acid and then deionized Rinse the solid with water until there is no chloride ion and sulfate ion, dry it under vacuum at 40°C, and grind to obtain graphite oxide powder. The average particle size of the graphite oxide powder is 50 microns.

2) Then disperse the above 1 gram of graphite oxide in 1000 grams of deionized water, ultrasonically (150W water bath) at 20°C for 1 hour, then add 50mL of sulfuric acid (concentration: 20% by weight) at 10°C, after 30 minutes The precipitate was obtained by suction filtration, vacuum-dried at 40° C., and ground to obtain graphite oxide powder precipitated by sulfuric acid. The average particle size of the graphite oxide powder precipitated by sulfuric acid was 43 microns.

3) Take the above-mentioned graphite oxide powder precipitated by sulfuric acid, put it into a quartz semi-sealed tube under the protection of N ₂ and put it into a tube furnace preheated to 700° C., take it out after heat treatment for 10 seconds, and obtain a graphene electrode active material. The surface morphology of the graphene electrode active material is determined by scanning electron microscopy to be a lamellar microstructure. The graphene electrode active material has a specific surface area of 412 m ² /g and an average pore diameter of 2.8 nm. It can be seen from infrared spectroscopy that the surface of the graphene electrode active material has carbonyl groups and hydroxyl groups.

4) Mix the above-mentioned graphene electrode active material with the conductive agent acetylene black and the binder polytetrafluoroethylene in a mass ratio of 80:10:10, stir the above-mentioned mixture to a slurry state under the state of distilled water being added dropwise, and dry After being dried, it is pressed into thin sheets and then pressed on a nickel foam current collector to obtain a supercapacitor electrode sheet. The relevant performance of its supercapacitor was tested in a three-electrode system. In this system, 6mol/L KOH aqueous solution was selected as the electrolyte, the platinum sheet was used as the counter electrode, and the mercury-mercuric oxide electrode was used as the reference electrode.

At a constant current density of 0.1A/g, the specific capacitance is 483F/g, and at a constant current density of 1A/g, the specific capacitance reaches 275F/g, after charging and discharging 5000 times at a constant current density of 1A/g , The capacity retention rate is 85%. Its equivalent series resistance is 0.29 ohms.

Example 3

1) Take by weighing 10 grams of natural flake graphite (-10 order), and 5 grams of sodium nitrate, under ice bath, join in the 230ml concentrated sulfuric acid (concentration 98% by weight), then add 30 grams of potassium permanganate, remove In an ice bath, the temperature was raised to 32-38°C, and the mixture was kept stirring during the process. When the reactant turns pink, add the reactant to 1.5 liters of deionized water, slowly add hydrogen peroxide with a concentration of 3% by weight until no bubbles are formed, and filter to obtain a solid. Rinse the solid with 0.1mol/L dilute hydrochloric acid and then deionized water until there is no chloride ion and sulfate ion, dry it in vacuum at 40°C, and grind to obtain graphite oxide powder. The average particle size of the graphite oxide powder is 500 microns.

2) Then disperse the above 1 gram of graphite oxide in 1000 grams of deionized water, ultrasonicate (150W water bath) at 50°C for 2 hours, then add 50mL of concentrated HCl (37% by weight) at 70°C for 60 minutes Afterwards, the precipitate was obtained by suction filtration, dried in vacuum at 40° C., and then ground to obtain graphite oxide powder precipitated by hydrochloric acid. The hydrochloric acid-precipitated graphite oxide powder had an average particle diameter of 150 micrometers.

3) Take the above-mentioned graphite oxide powder precipitated by hydrochloric acid, put it into a quartz semi-sealed tube under the protection of Ar, put it into a tube furnace preheated to 1000° C., take it out after heat treatment for 20 seconds, and obtain a graphene electrode active material. The surface morphology of the graphene electrode active material is determined by scanning electron microscopy to be a lamellar microstructure. The graphene electrode active material has a specific surface area of 382 m ² /g and an average pore diameter of 2.7 nm. It can be seen from infrared spectroscopy that the surface of the graphene electrode active material has carbonyl groups and hydroxyl groups.

4) Mix the above-mentioned graphene electrode active material with the binder polytetrafluoroethylene in a mass ratio of 90:10, stir the above-mentioned mixture to a slurry state under the state of adding distilled water dropwise, and press it into thin sheets after drying. On the nickel foam collector plate. The relevant performance of its supercapacitor was tested in a three-electrode system. In this system, 6mol/L KOH aqueous solution was selected as the electrolyte, the platinum sheet was used as the counter electrode, and the mercury-mercuric oxide electrode was used as the reference electrode.

At a constant current density of 0.1A/g, the specific capacitance is 528F/g, and at a constant current density of 1A/g, the specific capacitance reaches 373F/g, after charging and discharging 5000 times at a constant current density of 1A/g , The capacity retention rate was 86%. Its equivalent series resistance is 0.24 ohms.

Example 4

1) Take by weighing 10 grams of natural flake graphite (200 orders), and 5 grams of sodium nitrate, under ice bath, join in the 230ml vitriol oil (concentration 98% by weight), then add 30 grams of potassium permanganate, remove ice bath, warming up to 32-38°C, keeping stirring during this process. When the reactant turns pink, add the reactant to 1.5 liters of deionized water, slowly add hydrogen peroxide with a concentration of 3% by weight until no bubbles are formed, filter to obtain a solid, first use 0.1mol/L dilute hydrochloric acid and then deionized Rinse the solid with water until there is no chloride ion and sulfate ion, dry it under vacuum at 40°C, and grind to obtain graphite oxide powder. The average particle size of the graphite oxide powder is 10 microns.

2) Then disperse the above 1 gram of graphite oxide in 500 grams of deionized water, ultrasonically (150W water bath) at 80°C for 1 hour, then add 50mL of sulfuric acid (concentration: 20% by weight) at 80°C, after 30 minutes The precipitate was obtained by suction filtration, dried in vacuum at 40° C., and ground to obtain graphite oxide powder precipitated by sulfuric acid. The graphite oxide powder precipitated by sulfuric acid had an average particle diameter of 5 micrometers.

3) Take the above-mentioned graphite oxide powder precipitated by hydrochloric acid, put it into a quartz semi-sealed tube under the protection of N ₂ and put it into a tube furnace preheated to 1100° C., take it out after heat treatment for 20 seconds, and obtain a graphene electrode active material. The surface morphology of the graphene electrode active material is determined by scanning electron microscopy to be a lamellar microstructure. The graphene electrode active material has a specific surface area of 418 m ² /g and an average pore diameter of 2.4 nm. It can be seen from infrared spectroscopy that the surface of the graphene electrode active material has carbonyl groups and hydroxyl groups.

4) Mix the above-mentioned graphene electrode active material with the conductive agent acetylene black and the binder polytetrafluoroethylene in a mass ratio of 80:10:10, stir the above-mentioned mixture to a slurry state under the state of distilled water being added dropwise, and dry After drying, it is pressed into thin sheets and then pressed on the nickel foam collector plate. The relevant performance of its supercapacitor was tested in a three-electrode system. In this system, 6mol/L KOH aqueous solution was selected as the electrolyte, the platinum sheet was used as the counter electrode, and the mercury-mercuric oxide electrode was used as the reference electrode.

At a constant current density of 0.1A/g, the specific capacitance is 463F/g, and at a constant current density of 1A/g, the specific capacitance reaches 262F/g, after charging and discharging 5000 times at a constant current density of 1A/g , The capacity retention rate is 85%. Its equivalent series resistance is 0.27 ohms.

Example 5

1) Take by weighing 10 grams of natural flake graphite (32 orders), and 5 grams of sodium nitrate, under ice bath, join in the 230ml vitriol oil (concentration 98% by weight), then add 30 grams of potassium permanganate, remove the ice bath, warming up to 32-38°C, keeping stirring during this process. When the reactant turns pink, add the reactant to 1.5 liters of deionized water, slowly add hydrogen peroxide with a concentration of 3% by weight until no bubbles are formed, filter to obtain a solid, first use 0.1mol/L dilute hydrochloric acid and then deionized Rinse the solid with water until there are no chloride ions and sulfate ions. After vacuum drying at 40° C., grind to obtain graphite oxide powder, the graphite oxide powder has an average particle size of 130 microns.

2) Then disperse 1 gram of graphite oxide above in 1000 grams of deionized water, ultrasonicate (150W water bath) at 20°C for 2 hours, then add 50mL of concentrated HCl (37% by weight) at 5°C for 120 minutes Afterwards, the precipitate was obtained by suction filtration, dried in vacuum at 40° C., and then ground to obtain graphite oxide powder precipitated by hydrochloric acid. The hydrochloric acid-precipitated graphite oxide powder had an average particle diameter of 100 micrometers.

3) Take the above-mentioned graphite oxide powder precipitated by hydrochloric acid, put it into a quartz semi-sealed tube under the protection of Ar, put it into a tube furnace preheated to 1150° C., take it out after heat treatment for 10 seconds, and obtain a graphene electrode active material. The surface morphology of the graphene electrode active material is determined by scanning electron microscopy to be a lamellar microstructure. The graphene electrode active material has a specific surface area of 376 m ² /g and an average pore diameter of 2.6 nm. It can be seen from infrared spectroscopy that the surface of the graphene electrode active material has carbonyl groups and hydroxyl groups.

4) Mix the above-mentioned graphene electrode active material with the binder polytetrafluoroethylene in a mass ratio of 90:10, stir the above-mentioned mixture to a slurry state under the state of adding distilled water dropwise, and press it into thin sheets after drying. On the nickel foam collector plate. The relevant performance of its supercapacitor was tested in a three-electrode system. In this system, 6mol/L KOH aqueous solution was selected as the electrolyte, the platinum sheet was used as the counter electrode, and the mercury-mercuric oxide electrode was used as the reference electrode.

At a constant current density of 0.1A/g, the specific capacitance is 513F/g, and at a constant current density of 1A/g, the specific capacitance reaches 361F/g, after charging and discharging 5000 times at a constant current density of 1A/g , the capacity retention rate is 83%. Its equivalent series resistance is 0.26 ohms.

Example 6

1) Take by weighing 10 grams of natural flake graphite (200 orders), and 5 grams of sodium nitrate, under ice bath, join in the 230ml vitriol oil (concentration 98% by weight), then add 30 grams of potassium permanganate, remove ice bath, warming up to 32-38°C, keeping stirring during this process. When the reactant turns pink, add the reactant to 1.5 liters of deionized water, slowly add hydrogen peroxide with a concentration of 3% by weight until no bubbles are formed, filter to obtain a solid, first use 0.1mol/L dilute hydrochloric acid and then deionized Rinse the solid with water until there is no chloride ion and sulfate ion, dry it under vacuum at 40°C, and grind to obtain graphite oxide powder. The average particle size of the graphite oxide powder is 80 microns.

2) Then disperse the above 1 gram of graphite oxide in 500 grams of deionized water, ultrasonically (150W water bath) at 20°C for 1 hour, then add 50mL of concentrated sulfuric acid (concentration: 20% by weight) at 35°C for 60 minutes Afterwards, the precipitate was obtained by suction filtration, dried in vacuum at 40° C., and then ground to obtain graphite oxide powder precipitated by sulfuric acid. The average particle size of the graphite oxide powder precipitated by sulfuric acid was 60 microns.

3) Take the above-mentioned graphite oxide powder precipitated by sulfuric acid, put it into a quartz semi-sealed tube under the protection of He, put it into a tube furnace preheated to 800 ° C, take it out after heat treatment for 30 seconds, and obtain a graphene electrode active material. The surface morphology of the graphene electrode active material is determined by scanning electron microscopy to be a lamellar microstructure. The graphene electrode active material has a specific surface area of 452 m ² /g and an average pore diameter of 2.9 nm. It can be seen from infrared spectroscopy that the surface of the graphene electrode active material has carbonyl groups and hydroxyl groups.

4) Mix the above-mentioned graphene electrode active material with the conductive agent acetylene black and the binder polytetrafluoroethylene in a mass ratio of 80:10:10, stir the above-mentioned mixture to a slurry state under the state of distilled water being added dropwise, and dry After drying, it is pressed into thin sheets and then pressed on the nickel foam collector plate. The relevant performance of its supercapacitor was tested in a three-electrode system. In this system, 6mol/L KOH aqueous solution was selected as the electrolyte, the platinum sheet was used as the counter electrode, and the mercury-mercuric oxide electrode was used as the reference electrode.

At a constant current density of 0.1A/g, the specific capacitance is 463F/g, and at a constant current density of 1A/g, the specific capacitance reaches 255F/g, after charging and discharging 5000 times at a constant current density of 1A/g , The capacity retention rate was 89%. Its equivalent series resistance is 0.29 ohms.

Example 7

1) Take by weighing 10 grams of natural flake graphite (32 orders), and 5 grams of sodium nitrate, under ice bath, join in the 230ml vitriol oil (concentration 98% by weight), then add 30 grams of potassium permanganate, remove the ice bath, warming up to 32-38°C, keeping stirring during this process. When the reactant turns pink, add the reactant to 1.5 liters of deionized water, slowly add hydrogen peroxide with a concentration of 3% by weight until no bubbles are formed, filter to obtain a solid, first use 0.1mol/L dilute hydrochloric acid and then deionized Rinse the solid with water until there is no chloride ion and sulfate ion, dry it under vacuum at 40°C, and grind to obtain graphite oxide powder. The average particle size of the graphite oxide powder is 90 microns.

2) Then disperse the above 1 gram of graphite oxide in 800 grams of deionized water, ultrasonically (150W water bath) at 20°C for 1 hour, then add 50mL of concentrated phosphoric acid (concentration: 30% by weight) at 35°C for 70 minutes Afterwards, the precipitate was obtained by suction filtration, dried in vacuum at 40° C., and then ground to obtain graphite oxide powder precipitated by sulfuric acid. The average particle size of the graphite oxide powder precipitated by sulfuric acid was 50 microns.

3) Take the above-mentioned graphite oxide powder precipitated by sulfuric acid, put it into a quartz semi-sealed tube under the protection of nitrogen and argon (1:1 volume ratio), put it into a tube furnace preheated to 800 ° C, and take it out after heat treatment for 30 seconds , to obtain the graphene electrode active material. The surface morphology of the graphene electrode active material is determined by scanning electron microscopy to be a lamellar microstructure. The graphene electrode active material has a specific surface area of 417 m ² /g and an average pore diameter of 2.2 nm. It can be seen from infrared spectroscopy that the surface of the graphene electrode active material has carbonyl groups and hydroxyl groups.

4) Mix the above-mentioned graphene electrode active material with the conductive agent acetylene black and the binder polytetrafluoroethylene in a mass ratio of 80:10:10, stir the above-mentioned mixture to a slurry state under the state of distilled water being added dropwise, and dry After drying, it is pressed into thin sheets and then pressed on the nickel foam collector plate. The relevant performance of its supercapacitor was tested in a three-electrode system. In this system, 6mol/L KOH aqueous solution was selected as the electrolyte, the platinum sheet was used as the counter electrode, and the mercury-mercuric oxide electrode was used as the reference electrode.

At a constant current density of 0.1A/g, the specific capacitance is 423F/g, and at a constant current density of 1A/g, the specific capacitance reaches 235F/g, after charging and discharging 5000 times at a constant current density of 1A/g , The capacity retention rate is 85%. Its equivalent series resistance is 0.22 ohms.

Example 8

1) Take by weighing 10 grams of natural flake graphite (2000 orders), and 5 grams of sodium nitrate, under ice bath, join in the 230ml vitriol oil (concentration 98% by weight), then add 30 grams of potassium permanganate, remove ice bath, warming up to 32-38°C, keeping stirring during this process. When the reactant turns pink, add the reactant to 1.5 liters of deionized water, slowly add hydrogen peroxide with a concentration of 3% by weight until no bubbles are formed, filter to obtain a solid, first use 0.1mol/L dilute hydrochloric acid and then deionized Rinse the solid with water until there is no chloride ion and sulfate ion, dry it under vacuum at 40°C, and grind to obtain graphite oxide powder. The average particle size of the graphite oxide powder is 20 microns.

2) Then disperse the above 1 gram of graphite oxide in 500 grams of deionized water, ultrasonically (150W water bath) at 20°C for 1 hour, then add 60mL of hydrobromic acid (concentration is 10% by weight) at 35°C, 120 Minutes later, the precipitate was obtained by suction filtration, dried in vacuum at 40° C., and ground to obtain graphite oxide powder precipitated by sulfuric acid. The average particle size of the graphite oxide powder precipitated by sulfuric acid was 12 microns.

3) Take the above-mentioned graphite oxide powder precipitated by sulfuric acid, put it into a quartz semi-sealed tube under the protection of He and nitrogen (1:1 volume ratio), put it into a tube furnace preheated to 800 ° C, and take it out after heat treatment for 60 seconds. The graphene electrode active material is obtained. The surface morphology of the graphene electrode active material is determined by scanning electron microscopy to be a lamellar microstructure. The graphene electrode active material has a specific surface area of 462 m ² /g and an average pore diameter of 2.6 nm. It can be seen from infrared spectroscopy that the surface of the graphene electrode active material has carbonyl groups and hydroxyl groups.

4) Mix the above-mentioned graphene electrode active material with the conductive agent acetylene black and the binder polytetrafluoroethylene in a mass ratio of 80:10:10, stir the above-mentioned mixture to a slurry state under the state of distilled water being added dropwise, and dry After drying, it is pressed into thin sheets and then pressed on the nickel foam collector plate. The relevant performance of its supercapacitor was tested in a three-electrode system. In this system, 6mol/L KOH aqueous solution was selected as the electrolyte, the platinum sheet was used as the counter electrode, and the mercury-mercuric oxide electrode was used as the reference electrode.

At a constant current density of 0.1A/g, the specific capacitance is 385F/g, and at a constant current density of 1A/g, the specific capacitance reaches 172F/g, after charging and discharging 5000 times at a constant current density of 1A/g , The capacity retention rate was 84%. Its equivalent series resistance is 0.32 ohms.

Example 9

1) Take by weighing 10 grams of natural flake graphite (100 orders), and 5 grams of sodium nitrate, under ice bath, join in the 230ml vitriol oil (concentration 98% by weight), then add 30 grams of potassium permanganate, remove the ice bath, warming up to 32-38°C, keeping stirring during this process. When the reactant turns pink, add the reactant to 1.5 liters of deionized water, slowly add hydrogen peroxide with a concentration of 3% by weight until no bubbles are formed, filter to obtain a solid, first use 0.1mol/L dilute hydrochloric acid and then deionized Rinse the solid with water until there is no chloride ion and sulfate ion, dry it under vacuum at 40°C, and grind to obtain graphite oxide powder. The average particle size of the graphite oxide powder is 120 microns.

2) Then disperse the above 1 gram of graphite oxide in 500 grams of deionized water, ultrasonically (150W water bath) at 20°C for 1 hour, then add 50mL of acetic acid (concentration: 80% by weight) at 35°C, after 120 minutes The precipitate was obtained by suction filtration, dried in vacuum at 40° C., and ground to obtain graphite oxide powder precipitated by sulfuric acid. The average particle size of the graphite oxide powder precipitated by sulfuric acid was 90 microns.

3) Take the above-mentioned graphite oxide powder precipitated by sulfuric acid, put it into a quartz semi-sealed tube under the protection of argon, put it into a tube furnace preheated to 800° C., take it out after heat treatment for 5 seconds, and obtain a graphene electrode active material. The surface morphology of the graphene electrode active material is determined by scanning electron microscopy to be a lamellar microstructure. The graphene electrode active material has a specific surface area of 402 m ² /g and an average pore diameter of 2.1 nm. It can be seen from infrared spectroscopy that the surface of the graphene electrode active material has carbonyl groups and hydroxyl groups.

4) Mix the above-mentioned graphene electrode active material with the conductive agent acetylene black and the binder polytetrafluoroethylene in a mass ratio of 80:10:10, stir the above-mentioned mixture to a slurry state under the state of distilled water being added dropwise, and dry After drying, it is pressed into thin sheets and then pressed on the nickel foam collector plate. The relevant performance of its supercapacitor was tested in a three-electrode system. In this system, 6mol/L KOH aqueous solution was selected as the electrolyte, the platinum sheet was used as the counter electrode, and the mercury-mercuric oxide electrode was used as the reference electrode.

At a constant current density of 0.1A/g, the specific capacitance is 337F/g, and at a constant current density of 1A/g, the specific capacitance reaches 165F/g, after charging and discharging 5000 times at a constant current density of 1A/g , The capacity retention rate was 88%. Its equivalent series resistance is 0.32 ohms.

Can find out by embodiment 1-9, comparative example 1-3 and Fig. 4, by the super capacitor electrode of graphene electrode active material of the present invention under the current density of 0.1A/g, specific capacitance reaches 337-528F/ g; at a current density of 1A/g, the specific capacitance reaches 165-373F/g; after charging and discharging 5000 times at a current density of 1A/g, the capacity retention rate remains above 83%, which is significantly higher than that of Comparative Examples 1-3 The electrode active material in the supercapacitor electrode. Moreover, the equivalent series resistance of the supercapacitor electrode with the graphene electrode active material of the present invention is also significantly smaller than that of the supercapacitor electrode with the electrode active material of Reference Documents 1-3. In addition, it can be seen from FIG. 2 that the surface of the graphene electrode active material obtained according to the present invention has more oxygen-containing groups such as carbonyl groups and hydroxyl groups. It can be seen from Fig. 3 that the shape of the curve is approximately rectangular, and as the scan rate increases, the shape of the curve remains substantially rectangular, indicating that the power characteristics of the supercapacitor using the graphene active material of the present invention are good.

Claims (13)

1. a preparation method of graphene electrode active material, is characterized in that, the method may further comprise the steps: 1) Dispersing the graphite oxide powder in deionized water to obtain a dispersion, contacting the dispersion with an acid and then separating the solid from the liquid to obtain a solid precipitate, drying and grinding the solid precipitate to obtain an acid-precipitated graphite oxide powder; wherein, With respect to each gram of graphite oxide powder described in step 1), the amount of the acid is 0.05-0.8 moles; 2) Heat-treat the acid-precipitated graphite oxide powder obtained in step 1) at a temperature of 600-1200° C. for 1-60 seconds in an inert gas atmosphere. 2. The method according to claim 1, wherein the concentration of the graphite oxide powder in the dispersion in step 1) is 0.05-0.25% by weight. 3. The method according to claim 1, wherein the concentration of the graphite oxide powder in the dispersion in step 1) is 0.09-0.2% by weight. 4. The method according to claim 1, wherein the average particle diameter of the graphite oxide powder in the dispersion liquid in step 1) is 5-600 microns. 5. The method according to claim 1, wherein, relative to each gram of the graphite oxide powder in step 1), the amount of the acid is 0.07-0.7 mol. 6. The method according to claim 1, wherein the acid is one or more of hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, hydrobromic acid, hydroiodic acid and acetic acid. 7. The method according to claim 1 or 5, wherein the temperature of the contact precipitation of the dispersion liquid with the acid is 0-100° C., and the time of contact precipitation is 5-240 minutes. 8 . The method according to claim 1 , wherein, in step 2), the heat treatment temperature is 700-1150° C., and the heat treatment time is 5-30 seconds. 9. The method according to claim 1, wherein the average particle diameter of the acid-precipitated graphite oxide powder obtained in step 1) is 0.05-300 microns. 10. A graphene electrode active material, characterized in that, the graphene electrode active material is prepared by the method described in any one of claims 1-9. 11. A supercapacitor electrode material, the supercapacitor electrode material contains a binding agent, characterized in that the supercapacitor electrode material also contains the graphene electrode active material according to claim 10. 12. A supercapacitor electrode sheet, the electrode sheet comprising a current collector and an electrode material loaded on the current collector, characterized in that the electrode material is the supercapacitor electrode material according to claim 11. 13. the application of graphene electrode active material described in claim 10 in supercapacitor.