CN115411243A - Graphene-based lithium battery positive electrode slurry and preparation method thereof - Google Patents

Graphene-based lithium battery positive electrode slurry and preparation method thereof Download PDF

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CN115411243A
CN115411243A CN202211037538.0A CN202211037538A CN115411243A CN 115411243 A CN115411243 A CN 115411243A CN 202211037538 A CN202211037538 A CN 202211037538A CN 115411243 A CN115411243 A CN 115411243A
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graphene
positive electrode
powder
electrode slurry
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王长龙
周志武
卢小龙
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Shenzhen Langtaifeng Electronics Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0416—Methods of deposition of the material involving impregnation with a solution, dispersion, paste or dry powder
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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    • Y02E60/10—Energy storage using batteries

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Abstract

The invention relates to graphene-based lithium battery positive electrode slurry and a preparation method thereof, and belongs to the technical field of lithium ion batteries. The positive electrode slurry is composed of a composite active powder material, a conductive agent, a bonding agent and a solvent, wherein the composite active powder material takes nickel cobalt lithium manganate powder as a raw material, N-trimethoxysilylpropyl-N, N, N-trimethyl ammonium chloride is hydrolyzed and then condensed with surface hydroxyl groups of the N-trimethoxysilylpropyl-N, N, N-trimethyl ammonium chloride, so that the surface is electropositive, carbon nano tubes, nano graphene and modified graphene are assembled on the surface of the nickel cobalt lithium manganate by electrostatic adsorption, the high conductivity and high thermal conductivity of the graphene are utilized, the conductivity and thermal stability of the nickel cobalt lithium manganate are improved, meanwhile, the lithium ion deintercalation of the graphene is reduced, and the charge and discharge stability of a ternary material is improved; in addition, the modified graphene is in a corrugated shape, forms a point-line-surface conductive network with the acetylene black and the carbon nano-tubes, obtains higher conductivity, reduces the internal resistance of the cathode material to a certain extent, and improves the stability of the battery.

Description

Graphene-based lithium battery positive electrode slurry and preparation method thereof
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to graphene-based lithium battery positive electrode slurry and a preparation method thereof.
Background
The lithium ion battery can work in a high voltage window, has high discharge capacity, can work for a long time under specific conditions, and is widely applied; the mainstream cathode material commonly used at present mainly comprises LiCoO 2 、LiNiO 2 、LiMn 2 O 4 And ternary materials four main stream products.
The ternary material is a nickel-cobalt-manganese-based solid solution material synthesized by taking cobalt salt, nickel salt and manganese salt as raw materials and LiCoO 2 Compared with the ternary material, the platform is slightly lower, but the safety and the cyclicity are improved; and LiNiO 2 Compared with the ternary material, the ternary material has smaller energy density, but the stability is greatly improved; with LiMn 2 O 4 Compared with ternary materials, the ternary materials have the advantages of high-temperature performance and energy density, but are not few in safety. The ternary material has excellent comprehensive performance, and by adjusting the proportion of Co, ni and Mn in the material, anode materials with different performances can be obtained, and the designable space is larger. With the rapid development of electric automobiles, hybrid electric automobiles and intelligent equipment, the energy density and stability of lithium ion batteries are paid attention to widely, and the application aims to develop the anode slurry with high energy density and good stability on the basis of ternary materials.
Disclosure of Invention
In order to solve the technical problems mentioned in the background art, the invention aims to provide graphene-based lithium battery positive electrode slurry and a preparation method thereof.
The purpose of the invention can be realized by the following technical scheme:
the positive electrode slurry of the graphene-based lithium battery consists of composite active powder, a conductive agent, an adhesive and a solvent.
The composite active powder is prepared by the following method:
step A1: adjusting the pH value of an ethanol solution to 8.5-9.5 by using sodium hydroxide, adding lithium nickel cobalt manganese oxide powder, stirring at a high speed, refluxing for 3-4h at 68-75 ℃, calcining at high temperature in the preparation process of the lithium nickel cobalt manganese oxide powder to obtain high activity, generating a large amount of hydroxyl on the surface in an alkaline environment, filtering, taking a filter cake, washing with deionized water, and evaporating the filter cake to constant weight under reduced pressure to prepare activated active powder.
Further, the concentration of the ethanol solution is 30%, and the dosage ratio of the nickel-cobalt lithium manganate powder to the ethanol solution is 10g:85-100mL.
Furthermore, the chemical composition of the nickel cobalt lithium manganate powder is LiNi 0.8 Co 0.1 Mn 0.1 O 2 The mode particle diameter of the nickel cobalt lithium manganate powder is 10 +/-1 mu m.
Step A2: uniformly mixing an ethanol solution and acetone to serve as a dispersing substrate, adding activated powder, performing ultrasonic stirring at 30kHz, keeping the ultrasonic stirring state, simultaneously dropwise adding ammonia water and N-trimethoxysilylpropyl-N, N, N-trimethyl ammonium chloride, continuously performing ultrasonic stirring reaction for 1.2-2h after dropwise adding, hydrolyzing methoxyl of the N-trimethoxysilylpropyl-N, N, N-trimethyl ammonium chloride into silanol groups, condensing with hydroxyl on the surface of the activated powder, grafting the N-trimethoxysilylpropyl-N, N, N-trimethyl ammonium chloride on the surface of the activated powder by covalent bonds to form an organic layer with positive charges, adsorbing graphene through electrostatic interaction in the process of preparing anode slurry to form a core-shell structure, mutually dispersing the activated powder due to mutual repulsion of the positive charge organic layers on the surface layer to present a fluid-like characteristic, avoiding self-aggregation, being beneficial to uniform dispersion in the anode slurry, filtering reaction liquid, placing filter cakes in a hot air drying box, and drying to constant weight to prepare modified activated powder.
Further, the dosage ratio of the activated powder, the ethanol solution, the acetone, the N-trimethoxysilylpropyl-N, N, N-trimethyl ammonium chloride and the ammonia water is 10g:50-70mL:20-40mL:1.2-1.7mL:3-4mL, the concentration of the ethanol solution is 80%, and the concentration of the ammonia water is 22%.
Step A3: fully mixing modified active powder, a carbon nano tube, nano graphene and modified graphene through an airflow powder mixer, adding deionized water for ultrasonic dispersion, standing for 24 hours, enabling the carbon nano tube, the nano graphene and the modified graphene to be electronegative in water, assembling the modified active powder with electropositive property through electrostatic adsorption, pouring out supernatant, taking lower-layer concentrated solution, adding hydroiodic acid, stirring and reducing, carrying out suction filtration, taking filter cakes, and drying to constant weight to obtain the composite active powder.
Further, the mass ratio of the modified active powder, the carbon nano tube, the nano graphene and the modified graphene is (10) from 0.08 to 0.12.
The modified graphene is prepared by the following method:
step B1: preparing a potassium permanganate solution, dropwise adding nitric acid to adjust the pH value to be 4, then adding graphene oxide powder for ultrasonic dispersion, keeping high activity of oxygen-containing groups on the surface of the graphene oxide under an acidic oxidation condition, soaking for 24 hours, then ultrasonically stripping, taking stripped turbid liquid for centrifugal separation, washing a lower-layer precipitate with deionized water until the pH value of a washing liquid is not lower than 6, and then drying the precipitate in a vacuum oven to obtain the flaky graphene.
Furthermore, the mass fraction of the potassium permanganate solution is 3.8-4.5%.
And step B2: and (2) taking hydroxycitric acid, 4-dimethylaminopyridine and deionized water, stirring and dissolving, adding the flaky graphene, heating to 88-95 ℃, refluxing for 4-6h, reacting the hydroxycitric acid with oxygen-containing groups on the surface of the flaky graphene to enable the flaky graphene to be in a corrugated shape, then performing suction filtration, taking a filter cake, washing with the deionized water, and drying to prepare the modified graphene.
Further, the dosage ratio of the flake graphene, the hydroxycitric acid and the 4-dimethylaminopyridine is 10g:0.1-0.18g:50-70mg.
A preparation method of graphene-based lithium battery positive electrode slurry specifically comprises the following steps:
step S1: premixing an adhesive and a solvent to obtain a kneading liquid;
step S2: uniformly mixing the composite active powder and the conductive agent, adding a kneading liquid, adding the kneading liquid into a kneader to prepare a composite material, and adding a solvent under a stirring state to adjust the viscosity to be 6500 +/-100 cP to prepare the anode slurry.
Further, the binder is polyvinylidene fluoride.
Further, the solvent is N-methyl-2-pyrrolidone.
Further, the conductive agent is acetylene black.
Furthermore, the mass ratio of the composite active powder, the conductive agent and the adhesive is 88-93:1.7-2.1:2.5-3.2.
The invention has the beneficial effects that:
1. the invention provides a method for modifying nickel cobalt lithium manganate, which comprises the steps of taking nickel cobalt lithium manganate powder as a raw material, activating the nickel cobalt lithium manganate powder in an alkaline alcohol solution to generate a large number of hydroxyl groups on the surface, hydrolyzing N-trimethoxysilylpropyl-N, N, N-trimethyl ammonium chloride, and then condensing the hydrolyzed N-trimethoxysilylpropyl-N, N, N-trimethyl ammonium chloride with the hydroxyl groups to enable the surface of the nickel cobalt lithium manganate to be positively charged, assembling a carbon nano tube, nano graphene and modified graphene on the surface of the nickel cobalt lithium manganate by electrostatic adsorption, wherein the modified graphene with a larger sheet diameter is mainly attached to the surface of powder particles, and the carbon nano tube and the nano graphene are filled in gaps to protect the nickel cobalt lithium manganate.
2. According to the invention, the modified graphene is used in the nickel cobalt lithium manganate, hydroxyl citric acid is utilized to react with oxygen-containing groups on the surface of the flaky graphene, so that the graphene is in a corrugated shape, and is assembled on the surface of the nickel cobalt lithium manganate to form a point-line-surface conductive network with acetylene black and a carbon nano tube, thereby obtaining higher conductivity, reducing the internal resistance of a positive electrode material to a certain extent, and improving the stability of a battery.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
The composite active powder is prepared by the embodiment specifically comprising the following steps:
1) Preparation of modified graphene
Stripping: preparing a 3.8 mass percent potassium permanganate solution, dropwise adding nitric acid to adjust the pH value to be 4, then adding graphene oxide powder for ultrasonic dispersion, soaking for 24 hours, then carrying out ultrasonic stripping, taking the stripped turbid liquid for centrifugal separation, washing the lower-layer precipitate with deionized water until the pH value of the washing liquid is not lower than 6, and then drying the precipitate in a vacuum oven to obtain the flaky graphene;
and (3) wrinkling: taking hydroxycitric acid, 4-dimethylaminopyridine and deionized water, stirring and dissolving, adding the flaky graphene, heating to 95 ℃, refluxing for 4 hours, then carrying out suction filtration, taking the filter cake, washing with the deionized water, carrying out suction filtration again, putting the filter cake into a drying oven, and drying to prepare the modified graphene, wherein the dosage ratio of the flaky graphene, the hydroxycitric acid and the 4-dimethylaminopyridine is 10g:0.18g:70mg.
2) Preparation of composite active powder
And (3) activation: taking 30% ethanol solution, adjusting the pH value to 9.5 by using sodium hydroxide, and adding lithium nickel cobalt manganese oxide powder into the ethanol solution according to the dosage of 85mL/10g, wherein the chemical composition of the lithium nickel cobalt manganese oxide powder is LiNi 0.8 Co 0.1 Mn 0.1 O 2 The particle size of the mode is 10 +/-1 mu m and is provided by Shenzhen technology Limited company, a uniform batch of raw materials is used in the following embodiment, the nickel cobalt lithium manganate powder is added and then stirred at 2800rpm for 10min at high speed, then the temperature is raised to 75 ℃ for reflux for 3h, after reaction, the mixture is filtered, a filter cake is taken out, the filter cake is washed by deionized water, the filter cake is filtered again, and the filter cake is decompressed and evaporated to constant weight to prepare the active powder material;
giving an electric charge: uniformly mixing an ethanol solution with the concentration of 80% and acetone to serve as a dispersing substrate, adding activated active powder, performing ultrasonic stirring at 30kHz, simultaneously dropwise adding 22% ammonia water and N-trimethoxysilylpropyl-N, N, N-trimethylammonium chloride while maintaining the ultrasonic stirring state, continuously performing ultrasonic stirring reaction for 1.2 hours after dropwise adding, filtering reaction liquid after reaction, placing a filter cake in a hot air drying box, and drying to constant weight to prepare modified active powder, wherein the dosage ratio of the activated active powder, the ethanol solution, the acetone, the N-trimethoxysilylpropyl-N, N, N-trimethylammonium chloride to the ammonia water is 10g:70mL of: 40mL of: 1.7mL:4mL;
compounding: and (2) adding the modified active powder, the carbon nano tube, the nano graphene and the modified graphene into an airflow powder mixer according to a mass ratio of 0.08 to 0.15, mixing for 20min, adding water with the mass being 5 times that of the composite powder, performing ultrasonic dispersion for 1h at 28kHz, standing for 24h, pouring out a supernatant, taking a lower-layer concentrated solution, adding hydroiodic acid with the mass being 0.8% that of the concentrated solution, stirring and reducing for 1h, performing suction filtration, taking a filter cake, and drying to constant weight to obtain the composite active powder.
Example 2
The composite active powder is prepared by the embodiment specifically comprising the following steps:
1) Preparation of modified graphene
Stripping: preparing a potassium permanganate solution with the mass fraction of 4.5%, dropwise adding nitric acid to adjust the pH value to 4, then adding graphene oxide powder for ultrasonic dispersion, soaking for 24 hours, then carrying out ultrasonic stripping, taking a stripped suspension for centrifugal separation, washing a lower-layer precipitate with deionized water until the pH value of a washing solution is not lower than 6, and then drying the precipitate in a vacuum oven to obtain flaky graphene;
and (3) wrinkling: taking hydroxycitric acid, 4-dimethylaminopyridine and deionized water, stirring and dissolving, adding flaky graphene, heating to 88 ℃, refluxing for 6 hours, then performing suction filtration, taking a filter cake, washing with the deionized water, performing suction filtration again, taking the filter cake, and drying in a drying oven to prepare modified graphene, wherein the dosage ratio of the flaky graphene, the hydroxycitric acid and the 4-dimethylaminopyridine is 10g:0.1g:50mg.
2) Preparation of composite active powder
And (3) activation: adjusting the pH value of 30% ethanol solution to 8.5 by using sodium hydroxide, adding lithium nickel cobalt manganese oxide powder into the ethanol solution according to 100mL/10g by using the dosage of the ethanol solution, stirring the mixture at 2800rpm for 10min, heating the mixture to 68 ℃, refluxing the mixture for 4h, filtering the mixture after reaction, taking a filter cake, washing the filter cake by using deionized water, filtering the filter cake, and evaporating the filter cake to constant weight under reduced pressure to prepare activated active powder;
giving an electric charge: uniformly mixing an ethanol solution with the concentration of 80% and acetone to serve as a dispersing substrate, adding activated active powder, performing ultrasonic stirring at 30kHz, simultaneously dropwise adding 22% ammonia water and N-trimethoxysilylpropyl-N, N, N-trimethylammonium chloride while maintaining the ultrasonic stirring state, continuously performing ultrasonic stirring reaction for 2 hours after dropwise adding, filtering reaction liquid after reaction, placing a filter cake in a hot air drying box, drying to constant weight, and preparing modified active powder, wherein the dosage ratio of the activated active powder, the ethanol solution, the acetone, the N-trimethoxysilylpropyl-N, N, N-trimethylammonium chloride to the ammonia water is 10g:50mL of: 20mL of: 1.2mL:3mL;
compounding: and (2) adding the modified active powder, the carbon nano tube, the nano graphene and the modified graphene into an airflow powder mixer according to a mass ratio of 0.1 to 0.12, mixing for 20min, adding water with the mass being 5 times that of the composite powder, performing ultrasonic dispersion for 1h at 28kHz, standing for 24h, pouring out supernatant, taking out lower-layer concentrated solution, adding hydroiodic acid with the mass being 0.9% that of the concentrated solution, stirring and reducing for 1h, performing suction filtration, taking out filter cakes, and drying to constant weight to prepare the composite active powder.
Example 3
The composite active powder is prepared by the following specific implementation process:
1) Preparation of modified graphene
Stripping: preparing a potassium permanganate solution with the mass fraction of 4.0%, dropwise adding nitric acid to adjust the pH value to 4, then adding graphene oxide powder for ultrasonic dispersion, soaking for 24 hours, then carrying out ultrasonic stripping, taking a stripped suspension for centrifugal separation, washing a lower-layer precipitate by using deionized water until the pH value of a washing solution is not lower than 6, and then drying the precipitate in a vacuum oven to obtain flaky graphene;
and (3) wrinkling: taking hydroxycitric acid, 4-dimethylaminopyridine and deionized water, stirring and dissolving, adding the flaky graphene, heating to 92 ℃, refluxing for 5 hours, then carrying out suction filtration, taking the filter cake, washing with the deionized water, carrying out suction filtration again, putting the filter cake into a drying oven, and drying to prepare the modified graphene, wherein the dosage ratio of the flaky graphene, the hydroxycitric acid and the 4-dimethylaminopyridine is 10g:0.14g:60mg.
2) Preparation of composite active powder
And (3) activation: adjusting the pH value of 30% ethanol solution to 9.0 by using sodium hydroxide, adding lithium nickel cobalt manganese oxide powder according to 95mL/10g by using the amount of the ethanol solution, wherein the mode particle size of the lithium nickel cobalt manganese oxide powder is 10 +/-1 mu m, stirring the lithium nickel cobalt manganese oxide powder at a high speed of 2800rpm for 10min after adding the lithium nickel cobalt manganese oxide powder, heating to 72 ℃, refluxing for 3.5h, filtering after reaction, taking a filter cake, washing the filter cake with deionized water, filtering the filter cake again, and evaporating the filter cake to constant weight under reduced pressure to prepare activated active powder;
giving an electric charge: uniformly mixing an ethanol solution with the concentration of 80% and acetone to serve as a dispersing substrate, adding activated active powder, performing ultrasonic stirring at 30kHz, simultaneously dropwise adding 22% ammonia water and N-trimethoxysilylpropyl-N, N, N-trimethyl ammonium chloride while maintaining the ultrasonic stirring state, continuing to perform ultrasonic stirring reaction for 1.6 hours after dropwise adding, filtering reaction liquid after reaction, placing a filter cake in a hot air drying box, and drying to constant weight to prepare modified active powder, wherein the dosage ratio of the activated active powder, the ethanol solution, the acetone, the N-trimethoxysilylpropyl-N, N, N-trimethyl ammonium chloride to the ammonia water is 10g:60mL of: 30mL of: 1.5mL:4mL;
compounding: and (2) adding the modified active powder, the carbon nano tube, the nano graphene and the modified graphene into an airflow powder mixer according to a mass ratio of 0.1.
In the following examples, positive electrode slurry was prepared using the composite active powder prepared in examples 1 to 3 as a raw material, wherein the binder was selected from polyvinylidene fluoride, the solvent was selected from N-methyl-2-pyrrolidone, and the conductive agent was selected from acetylene black.
Example 4
In this embodiment, the positive electrode slurry is prepared from the composite active powder prepared in example 1, and the specific implementation process is as follows:
step S1: the composite active powder prepared in the example 1, the conductive agent and the adhesive are mixed according to the mass ratio of 88:2.1:2.5, preparing materials, and stirring and premixing the adhesive and a solvent which is 3 times of the adhesive in mass to obtain a kneading liquid;
step S2: and (2) adding the composite active powder and the conductive agent into an airflow powder mixer, mixing for 10min, adding a kneading liquid, adding the kneading liquid into a kneader, pressurizing and kneading to prepare a composite material, slowly adding the solvent into the composite material under the stirring of 240rpm until the viscosity reaches 6500 +/-100 cP, and preparing the anode slurry.
Example 5
In this embodiment, the positive electrode slurry is prepared from the composite active powder prepared in example 2, and the specific implementation process is as follows:
step S1: the composite active powder prepared in the example 2, the conductive agent and the adhesive are mixed according to the mass ratio of 93:1.7:3.2, preparing materials, and stirring and premixing the adhesive and a solvent with the mass of 3 times of that of the adhesive to obtain a kneading liquid;
step S2: and (2) adding the composite active powder and the conductive agent into an airflow powder mixer, mixing for 10min, adding a kneading liquid, adding the kneading liquid into a kneader, pressurizing and kneading to prepare a composite material, slowly adding the solvent into the composite material under the stirring of 240rpm until the viscosity reaches 6500 +/-100 cP, and preparing the anode slurry.
Example 6
In this embodiment, the positive electrode slurry is prepared from the composite active powder prepared in example 3, and the specific implementation process is as follows:
step S1: the composite active powder prepared in the example 3, the conductive agent and the adhesive are mixed according to the mass ratio of 92:1.8:2.9, preparing materials, and stirring and premixing the adhesive and a solvent which is 3 times of the adhesive in mass to obtain a kneading liquid;
step S2: and (2) adding the composite active powder and the conductive agent into an airflow powder mixer, mixing for 10min, adding a kneading liquid, adding the kneading liquid into a kneader, pressurizing and kneading to prepare a composite material, slowly adding the solvent into the composite material under the stirring of 240rpm until the viscosity reaches 6500 +/-100 cP, and preparing the anode slurry.
Taking the positive electrode slurry prepared in the examples 4 to 6, coating the slurry on an Al current collector by using a scraper, drying the slurry for 10 hours at 80 ℃ in a vacuum drying oven, compacting the slurry by using a roller press, slicing the slurry to obtain a positive plate, drying the obtained positive plate for 12 hours at 120 ℃ in the vacuum drying oven, assembling a button battery by using a metal lithium plate as a negative electrode in a glove box filled with Ar (with the purity of 99.99 percent), and testing the conductivity and the electrochemical performance, wherein the charging and discharging voltage ranges are as follows: 2.75-4.2V, the test temperature is 25 ℃, the cycle is 500 times under the condition of charging at 1C and discharging at 6C, and the specific test data is shown in Table 1:
TABLE 1
Figure BDA0003817799110000091
Figure BDA0003817799110000101
As can be seen from table 1, the conductivity of the positive electrode sheet produced using the positive electrode slurry of the present invention was 5.96 to 6.18 × 10 -3 The lithium manganese oxide battery has the advantages of S/cm, higher conductivity, specific first-charge capacity of 192.215-198.581mAh/g, specific first-discharge capacity of 190.869-196.793mAh/g, capacity retention rate of 98.59-99.29% after 500 cycles, and higher stability compared with the existing lithium manganese nickel cobalt oxide battery anode material.
In the description of the specification, reference to the description of "one embodiment," "an example," "a specific example" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The foregoing is illustrative and explanatory only and is not intended to be exhaustive or to limit the invention to the precise embodiments described, and various modifications, additions, and substitutions may be made by those skilled in the art without departing from the scope of the invention or exceeding the scope of the claims.

Claims (9)

1. The graphene-based lithium battery positive electrode slurry is characterized by comprising composite active powder, a conductive agent, an adhesive and a solvent;
the composite active powder is prepared by the following method:
step A1: adjusting pH to 8.5-9.5 with ethanol solution, adding lithium nickel cobalt manganese oxide powder, mixing, refluxing at 68-75 deg.C for 3-4 hr, filtering, washing filter cake, and evaporating under reduced pressure to obtain active powder;
step A2: mixing an ethanol solution and acetone, adding activated active powder, performing ultrasonic stirring at 30kHz, simultaneously dropwise adding ammonia water and N-trimethoxysilylpropyl-N, N, N-trimethyl ammonium chloride while maintaining the ultrasonic stirring state, continuously performing ultrasonic stirring reaction for 1.2-2h after dropwise adding, filtering the reaction solution, taking a filter cake, and drying to prepare modified active powder;
step A3: mixing the modified active powder, the carbon nano tube, the nano graphene and the modified graphene, adding deionized water for ultrasonic dispersion, standing for 24 hours, pouring out supernatant, taking the lower-layer concentrated solution, adding hydroiodic acid, stirring for reduction, carrying out suction filtration, taking the filter cake, and drying to prepare the composite active powder.
2. The positive electrode slurry for a graphene-based lithium battery as claimed in claim 1, wherein in the step A1, the ratio of the lithium nickel cobalt manganese oxide powder to the ethanol solution is 10g:85-100mL, and the concentration of the ethanol solution is 30%.
3. The positive electrode paste for a graphene-based lithium battery as claimed in claim 2, wherein the chemical composition of the lithium nickel cobalt manganese oxide powder is LiNi 0.8 Co 0.1 Mn 0.1 O 2 The mode particle size of the nickel cobalt lithium manganate powder is 10 +/-1 mu m.
4. The positive electrode slurry for the graphene-based lithium battery as claimed in claim 3, wherein in the step A2, the ratio of the amount of the activated powder to the amount of the ethanol solution to the amount of the acetone to the amount of the N-trimethoxysilylpropyl-N, N, N-trimethylammonium chloride to the amount of the ammonia water is 10g:50-70mL:20-40mL:1.2-1.7mL:3-4mL, the concentration of the ethanol solution is 80%, and the concentration of the ammonia water is 22%.
5. The graphene-based lithium battery positive electrode slurry according to claim 4, wherein the mass ratio of the modified active powder material to the carbon nanotubes to the nano graphene to the modified graphene is 10.08-0.12.
6. The graphene-based lithium battery positive electrode slurry as claimed in claim 1, wherein the modified graphene is prepared by the following method:
step B1: preparing a potassium permanganate solution, dropwise adding nitric acid to adjust the pH value to 4, then adding graphene oxide powder for ultrasonic dispersion, soaking for 24 hours, then ultrasonically stripping, centrifuging, taking precipitate, washing until the pH value of a washing solution is not lower than 6, and then taking a filter cake and drying to prepare flaky graphene;
and step B2: and (2) taking hydroxycitric acid, 4-dimethylaminopyridine and deionized water, stirring for dissolving, adding the flaky graphene, heating to 88-95 ℃, refluxing for 4-6h, then performing suction filtration, taking a filter cake, washing, and drying to prepare the modified graphene.
7. The positive electrode slurry for the graphene-based lithium battery as claimed in claim 6, wherein the amount ratio of the flake graphene, the hydroxycitric acid and the 4-dimethylaminopyridine is 10g:0.1-0.18g:50-70mg.
8. The preparation method of the positive electrode slurry for the graphene-based lithium battery as claimed in claim 1, wherein the preparation method specifically comprises the following steps:
step S1: premixing an adhesive and a solvent to obtain a kneading liquid;
step S2: uniformly mixing the composite active powder and the conductive agent, adding a kneading liquid, adding the kneading liquid into a kneader to prepare a composite material, and adding a solvent under a stirring state to adjust the viscosity to be 6500 +/-100 cP to prepare the anode slurry.
9. The method for preparing the positive electrode slurry of the graphene-based lithium battery as claimed in claim 8, wherein the binder is polyvinylidene fluoride, the solvent is N-methyl-2-pyrrolidone, and the conductive agent is acetylene black.
CN202211037538.0A 2022-08-26 2022-08-26 Graphene-based lithium battery positive electrode slurry and preparation method thereof Pending CN115411243A (en)

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