WO2022127046A1

WO2022127046A1 - Preparation method for modified graphite electrode material

Info

Publication number: WO2022127046A1
Application number: PCT/CN2021/098368
Authority: WO
Inventors: 彭飞; 仰永军
Original assignee: 广东凯金新能源科技股份有限公司
Priority date: 2020-12-15
Filing date: 2021-06-04
Publication date: 2022-06-23
Also published as: CN112599741A; CN112599741B

Abstract

Disclosed is a preparation method for a modified graphite electrode material, comprising the following preparation steps: adding nitric acid solution into graphite, then adding a cationic polymer, and reacting in a constant temperature water bath while stirring to obtain a first reactant; sequentially introducing an ionic liquid and carbonyl sulfide into the first reactant to obtain a second reactant; washing the second reactant using deionized water, placing in a drying oven for curing treatment, ball milling using a ball mill, then placing the ball-milled powder in a high-temperature heating furnace for carbonization treatment to obtain a third reactant; mixing the third reactant and a conductive agent, grinding, then dispersing in anhydrous ethanol, adding an adhesive and potassium oxalate, stirring evenly, drying, and pelleting to obtain a modified graphite electrode material. The modified graphite electrode material obtained in the present invention has good charge and discharge performance and cycle performance.

Description

A kind of preparation method of modified graphite electrode material

CROSS-REFERENCE TO RELATED APPLICATIONS.

This application claims the priority of the Chinese patent application filed on December 15, 2020 with the application number 202011477581.X and the invention titled "A method for preparing a modified graphite electrode material", the entire contents of which are by reference Incorporated in this application.

technical field

The invention relates to the technical field of batteries, in particular to a preparation method of a modified graphite electrode material.

Background technique

With the increasing use of global energy, non-renewable energy sources such as fossil fuels are increasingly exhausted, and will cause serious pollution to the environment. Therefore, it is urgent to develop renewable energy such as hydrogen, wind, nuclear, geothermal, and solar energy. However, these new energies all have problems such as intermittent supply and difficult control. The problem that needs to be solved before using these new energies is to store them and then release them centrally. Therefore, a large-scale energy storage system needs to be built. Electrochemical energy storage has high operating energy efficiency, controllable replay time and good cycle performance, and has become a hot spot in current new energy research.

technical problem

Carbon materials, especially heteroatom-doped carbon materials, have the characteristics of high specific surface area, high electrical conductivity, high thermal conductivity, etc. The supercapacitors prepared with them have high specific capacitance, high current charge-discharge performance, high power density and long cycle life. It is one of the most important electrode materials in supercapacitors, with abundant resources, diverse structures and moderate cost. However, traditional carbon materials often have problems such as small specific surface area, low mass specific capacitance, and low power density, which requires a series of process operations such as modification to improve their performance as electrode materials. Yun et al. (Journal of Power Sources 2014; 262(0):79-85) and Yan et al. (Chemical Communications 2012; 48(86):10663-10665) both showed that sulfur-doped carbon materials are more efficient than undoped carbon materials The carbon material has a higher lithium-ion storage capacity. However, in the traditional technology, due to the high content of sulfur and the uneven distribution of sulfur, elemental sulfur particles will be precipitated during the charging and discharging process, which is not conducive to the improvement of the energy density of the battery.

technical solutions

According to various embodiments of the present application, a method for preparing a modified graphite electrode material is provided. By doping sulfur element, the battery has a higher lithium ion storage capacity, and the distribution of sulfur element is uniform. There will be no precipitation of elemental sulfur particles.

A preparation method of modified graphite electrode material, comprising the following preparation steps.

S1: adding a nitric acid solution to the graphite, adjusting the pH to 4-6, then adding a cationic polymer, and stirring the reaction in a constant temperature water bath at 100°C-120°C to obtain the first reactant.

S2: The ionic liquid and carbon oxysulfide are sequentially introduced into the first reactant, and the reaction is carried out at 100° C. to 150° C. for 0.5 h to 2 h to obtain the second reactant.

S3: Wash the second reactant with deionized water, then put it into a drying oven at 220°C-300°C for curing for 10h-15h, and then use a ball mill for 2h-3h, so that the particle size of the powder after ball milling is less than 2µm and then, under the protection of an inert gas, the ball-milled powder is placed in a high-temperature heating furnace for carbonization to obtain a third reactant.

S4: After mixing the third reactant and the conductive agent, grind, disperse in absolute ethanol, add a binder and potassium oxalate, stir evenly, dry, and press to obtain a modified graphite electrode material.

Further, in step S1, the mass concentration of the nitric acid solution is 1%, and the cationic polymer is one or a combination of two of aluminum hydroxy and zirconium hydroxy.

Further, in step S1, the mass ratio of the graphite to the cationic polymer is 1:0.01-0.1.

Further, in step S2, the ionic liquid is 1-butyl-3-methylimidazolium bromide or 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid.

Further, in step S2, the mass ratio of the first reactant and ionic liquid, carbon oxysulfide is 1: 0.01-0.1: 0.1-0.2.

Further, in step S3, the inert gas is nitrogen or argon.

Further, in step S3, the temperature of the carbonization treatment is 600°C-800°C, the pressure is 30 MPa-50 MPa, and the reaction time is 10h-20h.

Further, in step S4, the mass ratio of the third reactant to the conductive agent, anhydrous ethanol and the binder is 1:0.3-0.5:1-3:0.01-0.05.

Further, the conductive agent is one of acetylene black, carbon nanotubes, nanocarbon fibers, and expanded graphite.

Further, the binder is one of polyvinylidene fluoride, polyvinyl chloride polyvinyl alcohol, and sodium hydroxymethyl cellulose.

beneficial effect

In the present invention, the hydroxyl group of the cationic polymer forms coordination in the graphite, and then in the ionic liquid, the uncoordinated hydroxyl group in the cationic polymer reacts with carbon oxysulfide to generate a sulfur-containing compound on the surface of the graphite, and then, Through the curing process and the carbonization process, the sulfur-containing element compound is fixed and uniformly distributed on the surface of the graphite, and the finally obtained modified graphite electrode material has good charge-discharge performance and cycle performance.

Embodiments of the present invention

In order to facilitate understanding of the present invention, the present invention will be described more fully below. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that a thorough and complete understanding of the present disclosure is provided.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terms used herein in the description of the present invention are for the purpose of describing specific embodiments only, and are not intended to limit the present invention.

Example 1.

S1: adding a nitric acid solution with a mass concentration of 1% to the graphite, adjusting the pH to 4-6, then adding a cationic polymer, and stirring the reaction in a constant temperature water bath at 100°C-120°C to obtain the first reactant.

S3: Wash the second reactant with deionized water, then put it into a drying oven at 220°C-300°C for curing for 10h-15h, and then use a ball mill for 2h-3h, so that the particle size of the powder after ball milling is less than 2µm , and then, under the protection of nitrogen, the ball-milled powder is placed in a high-temperature heating furnace for carbonization treatment. , the third reactant is obtained.

Wherein, the cationic polymer is hydroxyaluminum; the mass ratio of the graphite to the cationic polymer is 1:0.01; the ionic liquid is 1-butyl-3-methylimidazolium bromide; the first reactant and the ionic liquid, The mass ratio of carbon oxysulfide is 1: 0.01: 0.1; the conductive agent is acetylene black, the adhesive is polyvinylidene fluoride, and the mass ratio of the third reactant to the conductive agent, absolute ethanol, and the adhesive is 1: 0.3:1:0.01.

After testing, the obtained modified graphite electrode material is used as a negative electrode material for lithium ion batteries. After the first charge-discharge cycle, the discharge specific capacity is 856mAh/g, and the first charge-discharge efficiency is 88.9%. After 100 cycles, the capacity retention rate is 91.3%, and no sulfur particles were precipitated during the charging and discharging process.

Example 2.

Wherein, the cationic polymer is hydroxyaluminum; the mass ratio of the graphite to the cationic polymer is 1:0.05; the ionic liquid is 1-butyl-3-methylimidazolium bromide; the first reactant and the ionic liquid, The mass ratio of carbon oxysulfide is 1: 0.01: 0.2; the conductive agent is acetylene black, the adhesive is polyvinylidene fluoride, and the mass ratio of the third reactant to the conductive agent, absolute ethanol, and the adhesive is 1: 0.3:1:0.01.

After testing, the obtained modified graphite electrode material is used as a negative electrode material for lithium-ion batteries. The discharge specific capacity after the first charge-discharge cycle is 882mAh/g, and the first charge-discharge efficiency is 90.3%. 93.1%, and no sulfur particles were precipitated during the charging and discharging process.

Example 3.

Wherein, the cationic polymer is hydroxyaluminum; the mass ratio of the graphite to the cationic polymer is 1:0.1; the ionic liquid is 1-butyl-3-methylimidazolium bromide; the first reactant and the ionic liquid, The mass ratio of carbon oxysulfide is 1: 0.01: 0.2; the conductive agent is acetylene black, the adhesive is polyvinylidene fluoride, and the mass ratio of the third reactant to the conductive agent, absolute ethanol, and the adhesive is 1: 0.3:1:0.01.

After testing, the obtained modified graphite electrode material is used as a negative electrode material for lithium ion batteries. The discharge specific capacity after the first charge-discharge cycle is 906mAh/g, and the first charge-discharge efficiency is 92.3%. After 100 cycles, the capacity retention rate is 92.7%, and no sulfur particles were precipitated during the charging and discharging process.

Comparative Example 1.

Wherein, the cationic polymer is hydroxyaluminum; the mass ratio of the graphite to the cationic polymer is 1:0.01; the ionic liquid is 1-butyl-3-methylimidazolium bromide; the first reactant and the ionic liquid, The mass ratio of carbon oxysulfide is 1: 0.01: 0.4; the conductive agent is acetylene black, the adhesive is polyvinylidene fluoride, and the mass ratio of the third reactant to the conductive agent, absolute ethanol, and the adhesive is 1: 0.3:1:0.01.

After testing, the obtained modified graphite electrode material is used as a negative electrode material for lithium ion batteries. The discharge specific capacity after the first charge-discharge cycle is 610mAh/g, and the first charge-discharge efficiency is 68.9%. After 100 cycles, the capacity retention rate is 77.5%, and there will be sulfur elemental particles precipitated during the charging and discharging process.

The above-mentioned embodiments are only preferred embodiments of the present invention, and cannot be used to limit the scope of protection of the present invention. Any insubstantial changes and substitutions made by those skilled in the art on the basis of the present invention belong to the scope of the present invention. Scope of protection claimed.

Claims

A preparation method of modified graphite electrode material, characterized in that, comprising the following preparation steps:

S1: adding a nitric acid solution to the graphite, adjusting the pH to 4-6, then adding a cationic polymer, and stirring the reaction in a constant temperature water bath at 100°C-120°C to obtain the first reactant;

S2: successively feeding ionic liquid and carbon oxysulfide into the first reactant, and reacting at 100°C-150°C for 0.5 h-2h to obtain the second reactant;

S3: Wash the second reactant with deionized water, then put it into a drying oven at 220°C-300°C for curing for 10h-15h, and then use a ball mill for 2h-3h, so that the particle size of the powder after ball milling is less than 2µm , and then, under the protection of inert gas, the ball-milled powder is placed in a high-temperature heating furnace for carbonization to obtain the third reactant;

S4: After mixing the third reactant and the conductive agent, grind, disperse in absolute ethanol, add a binder and potassium oxalate, stir evenly, dry, and press to obtain a modified graphite electrode material.
The method for preparing modified graphite electrode material according to claim 1, characterized in that, in step S1, the mass concentration of the nitric acid solution is 1%, and the cationic polymer is one or both of aluminum hydroxy and zirconium hydroxy. combination.
The method for preparing a modified graphite electrode material according to claim 1, wherein in step S1, the mass ratio of the graphite to the cationic polymer is 1:0.01-0.1.
The method for preparing a modified graphite electrode material according to claim 1, wherein in step S2, the ionic liquid is 1-butyl-3-methylimidazolium bromide or 1-butyl-3- Methylimidazole hexafluorophosphate ionic liquid.
The preparation method of modified graphite electrode material according to claim 1, is characterized in that, in step S2, the mass ratio of first reactant and ionic liquid, carbon oxysulfide is 1: 0.01-0.1: 0.1-0.2.
The method for preparing a modified graphite electrode material according to claim 1, wherein in step S3, the inert gas is nitrogen or argon.
The preparation method of the modified graphite electrode material according to claim 1, characterized in that, in step S3, the temperature of the carbonization treatment is 600°C-800°C, the pressure is 30 MPa-50 MPa, and the reaction time is 10h-20h.
The method for preparing a modified graphite electrode material according to claim 1, wherein in step S4, the mass ratio of the third reactant to the conductive agent, anhydrous ethanol and the binder is 1:0.3-0.5:1 -3:0.01-0.05.
The method for preparing a modified graphite electrode material according to claim 8, wherein the conductive agent is one of acetylene black, carbon nanotubes, nanocarbon fibers, and expanded graphite.
The method for preparing a modified graphite electrode material according to claim 8, wherein the binder is one of polyvinylidene fluoride, polyvinyl chloride polyvinyl alcohol, and sodium hydroxymethyl cellulose.