CN110921659A

CN110921659A - Preparation method of high-capacity artificial graphite negative electrode material

Info

Publication number: CN110921659A
Application number: CN201911267180.9A
Authority: CN
Inventors: 翟志明; 万水田
Original assignee: Inner Mongolia Sanxin New Material Technology Co Ltd
Current assignee: Inner Mongolia Sanxin New Material Technology Co Ltd
Priority date: 2019-12-11
Filing date: 2019-12-11
Publication date: 2020-03-27

Abstract

The invention discloses a preparation method of a high-capacity artificial graphite cathode material, which is characterized by comprising the following preparation steps: (1) shaping the raw materials; (2) mixing the raw materials with auxiliary materials; (3) heat treatment; (4) graphitizing; (5) and (5) grading and screening. Compared with the prior art for preparing the artificial graphite cathode material, the invention has simple working procedures and high yield of the preparation method; the negative electrode material D50 prepared by the method is between 5 and 15 mu m, and the specific surface area is 2m²The first discharge capacity of the battery made of the graphite cathode material of the lithium ion battery is more than 350mAh/g, and the first charge-discharge efficiency is more than 92%.

Description

Preparation method of high-capacity artificial graphite negative electrode material

Technical Field

The invention relates to the technical field of artificial graphite cathode materials of lithium ion batteries

Background

Lithium ion batteries have many advantages such as high voltage, high energy, long cycle life, no memory effect, etc., and have been widely used in the fields of consumer electronics, electric earth appliances, medical electronics, etc. The electric vehicle is gradually popularized in the traffic fields of pure electric vehicles, hybrid electric vehicles, electric bicycles, rail traffic, aerospace, ships and naval vessels and the like. Meanwhile, the lithium ion battery also shows good application prospects in the energy fields of large-scale renewable energy access, power grid peak regulation and frequency modulation, distributed energy storage, household energy storage, data center standby power supply, communication base stations, industrial energy conservation, green buildings and the like. Nowadays, lithium ion batteries are irreplaceable in the fields of electrochemical energy storage and power batteries, and the performance of the lithium ion batteries directly influences the development of modern energy storage equipment and electric vehicles.

Therefore, the experiment adopts needle coke with poor performance as a raw material and carries out modification treatment on the surface of the needle coke, so that the defect of poor compatibility between the needle coke and an electrolyte solution is overcome, and the discharge capacity, the discharge efficiency and the charge-discharge rate performance of the product are improved.

Disclosure of Invention

The invention aims to overcome the defect that the compatibility of the existing needle coke and an electrolyte solution is poor, and provides a high-capacity artificial graphite cathode material and a preparation method thereof.

The invention solves the technical problems through the following technical scheme.

The invention provides a preparation method of a graphite cathode material of a lithium ion battery, which comprises the following steps:

(1) crushing raw materials: and (3) grinding the needle coke into powder with the grain size D50 of 3-10 mu m.

(2) Mixing the raw materials and the auxiliary materials: mixing the raw material powder and asphalt in a mixer to obtain a mixture, wherein the mass ratio of the raw material powder to the asphalt is 60: 40-99: 1.

(3) And (3) heat treatment: and carrying out heat treatment on the mixture for 5-20 h at 200-700 ℃ under the protection of inert gas.

(4) Graphitization: graphitizing the mixture after heat treatment at 2800-3200 ℃ for 20-80 h.

(5) Grading and screening: and (4) screening and grading the graphitized sample by using a grader or an ultrasonic vibration screen.

The needle coke in the step (1) is needle coke before calcination.

In the step (2), the asphalt is one or a mixture of more of petroleum asphalt, coal asphalt or modified asphalt, and the average particle size D50 of the asphalt is 2-10 μm.

The performance parameters of the prepared high-rate artificial graphite cathode material are as follows: the D50 particle size is 6-25 μm, the specific surface area is less than or equal to 2m²And g, the discharge capacity of the prepared button cell is more than or equal to 350mAh/g, and the first efficiency of the prepared button cell is more than or equal to 92 percent.

Compared with the prior art, the invention has simple working procedure, stable product performance and high productivity, and the prepared product has the characteristics of high capacity and high efficiency in the aspect of electrical property by adopting the methods of crushing, heat treatment, graphitization and the like, the physical property of the product is effectively improved, and the button cell prepared by adopting the method has excellent comprehensive performance.

Drawings

Fig. 1 is a scanning electron microscope image of the artificial graphite negative electrode material prepared in example 5 of the present invention.

Detailed Description

The preparation steps of the present invention will be further described with reference to the following examples.

Example 1

Mixing needle coke (6 μm) and coal tar pitch (3 μm) 95:5 in a mixer, treating at 580 ℃ for 15h under the protection of nitrogen, and graphitizing the obtained material at 3000 ℃ for 48 h; after graphitization, screening is carried out, and the screened product D50 is 6.591 mu m. The capacity of the button cell made of the graphite cathode material is 352.7mAh/g, and the primary efficiency is 92.1%.

Example 2

Mixing needle coke (6 μm) and petroleum asphalt (3 μm) 95:5 in a mixer, treating at 650 ℃ for 8h under the protection of nitrogen, and graphitizing the obtained material at 2800 ℃ for 72 h; after graphitization, screening is carried out, and the screened product D50 is 7.247 mu m. The button cell prepared from the graphite cathode material has the capacity of 354.3mAh/g and the primary efficiency of 92.7%.

Example 3

Mixing needle coke (6 μm) and petroleum asphalt (5 μm) at a ratio of 90:10 in a mixer, treating at 650 ℃ for 12h under the protection of nitrogen, and graphitizing the obtained material at 3000 ℃ for 48 h; after graphitization, screening is carried out, and the screened product D50 is 7.955 mu m. The capacity of the button cell made of the graphite cathode material is 353.8mAh/g, and the primary efficiency is 92.9%.

Example 4

Mixing needle coke (8 μm) and modified asphalt (5 μm) at a ratio of 90:10 in a mixer, treating at 500 ℃ for 7h under the protection of nitrogen, and graphitizing the obtained material at 3000 ℃ for 36 h; after graphitization, screening was performed, and the screened product D50 was 11.326. mu.m. The button cell prepared from the graphite cathode material has the capacity of 355.9mAh/g and the primary efficiency of 92.5%.

Example 5

Mixing needle coke (4.5 μm) and coal tar pitch (5 μm) 85:15 in a mixer, treating at 650 ℃ for 10h under the protection of nitrogen, and graphitizing the obtained material at 3000 ℃ for 70 h; after graphitization, screening is carried out, and the screened product D50 is 9.356 mu m. The capacity of the button cell made of the graphite cathode material is 358.6mAh/g, and the primary efficiency is 93.7%.

Comparative example 1

Treating needle coke (6 microns) at 650 ℃ for 6 hours under the protection of nitrogen, and graphitizing the obtained material at 3000 ℃ for 72 hours; after graphitization, screening is carried out, and the screened product D50 is 7.101 mu m. The button cell prepared from the graphite cathode material has the capacity of 345.3mAh/g and the primary efficiency of 90.3%.

Effects of the embodiment

(1) The artificial graphite negative electrode materials of examples 1 to 5 and comparative example 1 were subjected to the particle size, specific surface area, and other item index tests, and the results are shown in table 1.

(2) The graphite negative electrode materials in examples 1 to 5 and comparative example 1 were tested for discharge capacity and first efficiency by button cell test method, and the results are shown in table 2.

The button cell test method comprises the steps of adding conductive carbon black into a carboxymethyl cellulose (CMC) aqueous solution, then adding a graphite negative electrode material, finally adding Styrene Butadiene Rubber (SBR), uniformly stirring, and uniformly coating slurry on a copper foil on a coating machine to prepare a pole piece. And (3) putting the coated pole piece into a vacuum drying oven at the temperature of 110 ℃ for vacuum drying for 4 hours, taking out the pole piece, and rolling the pole piece on a roller press for later use. The simulated cell was assembled in a hydrogen-charged German Braun glove box with an electrolyte of 1MLiPF6EC: DEC: DMC 1:1: l (volume ratio) and a metal foil as counter electrode. The capacity test was carried out on an ArbinBT2000 model U.S. Battery tester, with a charge-discharge voltage range of 0.005 to 2.0V and a charge-discharge rate of 0.1C.

TABLE 2 Performance parameters of the examples and comparative examples

As can be seen from the data of table 2, the discharge capacity and the first efficiency in comparative example 1 were low, and the specific surface area was large; the graphite cathode material prepared by the method has the advantages of small specific surface area, discharge capacity larger than 350mAh/g and primary efficiency larger than 92%.

Claims

1. The preparation method of the high-capacity artificial graphite cathode material is characterized by comprising the following preparation steps:

(1) shaping treatment of raw materials: shaping the needle coke into a mixture having an average particle diameter D50 of 3 to 10 μm and a tap density of 0.4 to 1.0g/cm³The raw material powder of (1);

(2) mixing the raw materials with auxiliary materials: mixing the raw material powder and asphalt in a mixer to obtain a mixture; the mass ratio of the raw material powder to the asphalt is 60: 40-99: 1;

(3) and (3) heat treatment: carrying out heat treatment on the mixture for 5-20 h at 200-700 ℃ under the protection of inert gas;

(4) graphitization: graphitizing the mixture after heat treatment at 2800-3200 ℃ for 20-80 h;

the asphalt in the step (2) is one or a mixture of more of petroleum asphalt, coal asphalt and/or modified asphalt, and the average particle size D50 of the asphalt is 2-10 mu m;

2. The method for preparing the graphite cathode material of the lithium ion battery according to claim 1, wherein the needle coke in the step (1) is pre-calcined coke.

3. The preparation method of the graphite negative electrode material for the lithium ion battery as claimed in claim 1, wherein the D50 of the needle coke in the step (1) is 3-10 μm.

4. The preparation method of the graphite cathode material of the lithium ion battery as claimed in claim 1, wherein the mass ratio of the needle coke to the asphalt in the step (1) is 60: 40-99: 1, preferably 80: 20-95: 5.

5. The preparation method of the graphite cathode material of the lithium ion battery as claimed in claim 1, wherein the asphalt in the step (1) is one or a mixture of coal asphalt, petroleum asphalt or modified asphalt.

6. The method for preparing the graphite anode material of the lithium ion battery as claimed in claim 1, wherein the mixing of the raw materials and the auxiliary materials in the step (2) is performed in a mixer, and the mixer is one of a conical mixer and a V-shaped mixer.

7. The preparation method of the graphite anode material for the lithium ion battery as claimed in claim 1, wherein the time of the heat treatment in the step (3) is 5-20 h.

8. The preparation method of the graphite negative electrode material for the lithium ion battery according to claim 1, wherein the heat treatment temperature in the step (3) is 200-700 ℃, preferably 400-600 ℃.

9. The method for preparing the graphite anode material of the lithium ion battery according to claim 1, wherein the inert gas in the step (3) is one or a mixture of nitrogen and argon.

10. The preparation method of the graphite cathode material of the lithium ion battery as claimed in claim 1, wherein the graphitization temperature in the step (4) is 2800-3200 ℃ for 20-80 h.

11. The method for preparing the graphite cathode material of the lithium ion battery according to claim 1, wherein in the step (5), the classification and screening equipment can be any one of a classifier and an ultrasonic vibration screen.