Artificial graphite negative electrode material

Abstract

The application discloses artificial graphite negative electrode material, including: pre-carbonization modified single particle graphitization material and secondary particle graphitization material;Pre-carbonization modified single particle graphitization material and secondary particle graphitization material weight ratio is 1-3:3-5;Pre-carbonization modified single particle graphitization material is coarse crushing after aggregate, then pre-carbonization treatment is carried out at 650-800 DEG C, then grinding, shaping, graphitization are obtained;Secondary particle graphitization material is obtained by crushing, granulating carbonization, shaping and graphitization after mixing aggregate and binder.The artificial graphite negative electrode material has excellent initial efficiency and high discharge capacity.

Description

Technical Field

[0001] This invention belongs to the field of lithium battery anode materials, and particularly relates to an artificial graphite anode material. Background Technology

[0002] With the sustainable development of the national economy and society, energy production and storage have become a crucial issue of global concern. Lithium-ion batteries, as a novel energy conversion device, are experiencing rapid development in the energy storage field. The anode material, as a key component of lithium-ion batteries, directly affects the energy density of the battery due to its specific capacity and operating voltage, playing a decisive role in its performance. Currently, artificial graphite is gradually becoming the preferred anode material for lithium-ion batteries.

[0003] Using carbonaceous raw materials with low impurity content as aggregate, artificial graphite is obtained through crushing, granulation, and graphitization to produce single-particle graphitized materials. During the graphitization process, irreversible gas expansion occurs due to the presence of small volatile molecules in the carbonaceous raw materials, especially non-metallic impurities such as N, O, and S. Within the temperature range of 1400-2100℃ during graphitization, under high-temperature heat treatment, sulfur and nitrogen bonded to heterocyclic rings in the carbon material structure are suddenly released as gaseous sulfides and nitrides within a narrow temperature range. This causes a sudden increase in volume, an irreversible expansion resulting from the destruction of the internal structure of the carbon material, which does not recover after the graphite product cools down from the high temperature. Therefore, although single-particle graphitized materials have high capacity, their initial coulombic efficiency is low, only around 84%, making them prone to lithium battery expansion, and their rate performance is generally poor. Summary of the Invention

[0004] Based on the above-mentioned technical problems, the present invention provides an artificial graphite anode material, including pre-carbonized modified single-particle graphitized material and secondary-particle graphitized material, which can effectively avoid lithium battery expansion and has both excellent first-time efficiency and high discharge capacity.

[0005] This invention provides an artificial graphite anode material, comprising: pre-carbonized modified single-particle graphitized material and secondary-particle graphitized material; the weight ratio of the pre-carbonized modified single-particle graphitized material to the secondary-particle graphitized material is 1-3:3-5.

[0006] The aggregates described in this invention are carbonaceous raw materials as commonly understood in the art. No specific limitation is made on the type of aggregates, including but not limited to coal-based coke and petroleum coke.

[0007] In preparing single-particle graphitized materials, the present invention performs pre-carbonization treatment after coarse crushing, which can effectively reduce the volatile content in the aggregate and improve the tap density of the single-particle graphitized materials.

[0008] Preferably, the weight ratio of pre-carbonized modified single-particle graphitized material to secondary-particle graphitized material is 2:3.

[0009] Preferably, the D50 particle size of the pre-carbonized modified single-particle graphitized material is 15-17 μm; the D50 particle size of the secondary-particle graphitized material is 12-14 μm.

[0010] Preferably, the pre-carbonized modified single-particle graphitized material is obtained by coarsely crushing the aggregate, pre-carbonizing it at 650-800℃, and then grinding, shaping, and graphitizing it.

[0011] Preferably, the pre-carbonization temperature is 700-750℃ and the pre-carbonization time is 5-15h.

[0012] Preferably, before pre-carbonization treatment, the aggregate is coarsely crushed to a D50 particle size ≤ 5 mm.

[0013] Preferably, the secondary particulate graphitized material is obtained by mixing aggregates and binders, followed by crushing, granulation, carbonization, shaping, and graphitization.

[0014] Preferably, the binder is asphalt.

[0015] Preferably, the amount of binder is 9-12% of the weight of the aggregate.

[0016] The preparation method of the artificial graphite anode material described in this invention is not specifically limited; it is sufficient to mix the pre-carbonized modified single-particle graphitized material and the secondary-particle graphitized material in a certain proportion.

[0017] The beneficial effects of this invention are:

[0018] This invention pre-carbonizes the aggregate before grinding, effectively reducing the content of volatile small molecules in the aggregate. This improves the tap density and capacity of the single-particle graphitized material and avoids the adverse effects of irreversible gas expansion during graphitization on the performance of the anode material. Blending the pre-carbonized modified single-particle graphitized material with secondary-particle graphitized material yields an artificial graphite anode material that exhibits both excellent initial efficiency and high discharge capacity, reaching 375.1 mAh / g, with an initial efficiency of 94.75%. Detailed Implementation

[0019] The technical solution of the present invention will be described in detail below through specific embodiments. However, it should be clearly stated that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0020] Example 1

[0021] An artificial graphite anode material comprises: pre-carbonized modified single-particle graphitized material (D50 particle size of 15.5 μm) and secondary-particle graphitized material (D50 particle size of 13 μm); the weight ratio of the pre-carbonized modified single-particle graphitized material to the secondary-particle graphitized material is 2:3. Wherein:

[0022] The pre-carbonized modified single-particle graphitized material uses needle coke as aggregate. The needle coke is coarsely crushed to a D50 particle size ≤ 5 mm. After coarse crushing, it is fed into a pre-carbonization furnace and pre-carbonized at 700℃ for 8 hours. After cooling to a temperature below 50℃, it is then obtained by grinding, shaping, graphitization, sieving and demagnetizing. Its D50 particle size is 15.5 μm.

[0023] Secondary granular graphitized material is obtained by mixing needle coke as aggregate and asphalt as binder, followed by crushing, granulation, carbonization, shaping, graphitization, sieving and demagnetization. Its D50 particle size is 13μm; the weight of asphalt is 12% of the weight of needle coke.

[0024] Example 2

[0025] An artificial graphite anode material comprises: pre-carbonized modified single-particle graphitized material (D50 particle size of 15.5 μm) and secondary-particle graphitized material (D50 particle size of 13 μm); the weight ratio of the pre-carbonized modified single-particle graphitized material to the secondary-particle graphitized material is 2:3. Wherein:

[0026] The pre-carbonized modified single-particle graphitized material is identical to Example 1 in all steps and parameters except that the pre-carbonization temperature is changed from 700°C in Example 1 to 650°C.

[0027] The secondary particulate graphitized material is the same as in Example 1.

[0028] Example 3

[0029] An artificial graphite anode material comprises: pre-carbonized modified single-particle graphitized material (D50 particle size of 15.5 μm) and secondary-particle graphitized material (D50 particle size of 13 μm); the weight ratio of the pre-carbonized modified single-particle graphitized material to the secondary-particle graphitized material is 2:3. Wherein:

[0030] The pre-carbonized modified single-particle graphitized material is identical to Example 1 in all steps and parameters except that the pre-carbonization temperature is changed from 700°C in Example 1 to 800°C.

[0031] The secondary particulate graphitized material is the same as in Example 1.

[0032] Example 4

[0033] An artificial graphite anode material comprises: pre-carbonized modified single-particle graphitized material (D50 particle size of 15.5 μm) and secondary-particle graphitized material (D50 particle size of 13 μm); the weight ratio of the pre-carbonized modified single-particle graphitized material to the secondary-particle graphitized material is 2:3. Wherein:

[0034] The pre-carbonized modified single-particle graphitized material is identical to Example 1 in all steps and parameters except that the pre-carbonization temperature is changed from 700°C in Example 1 to 800°C.

[0035] The secondary particulate graphitized material is identical to Example 1 in all steps and parameters except that the weight of the asphalt is changed from 12% to 9% of the weight of the needle coke in Example 1.

[0036] Example 5

[0037] An artificial graphite anode material comprises: pre-carbonized modified single-particle graphitized material (D50 particle size of 16 μm) and secondary-particle graphitized material (D50 particle size of 14 μm); the weight ratio of the pre-carbonized modified single-particle graphitized material to the secondary-particle graphitized material is 3:5. Wherein:

[0038] The pre-carbonized modified single-particle graphitized material uses needle coke as aggregate. The needle coke is coarsely crushed to a D50 particle size ≤ 5 mm. After coarse crushing, it is fed into a pre-carbonization furnace and pre-carbonized at 650℃ for 10 h. After cooling to a temperature below 80℃, it is then obtained by grinding, shaping, graphitization, sieving and demagnetizing. Its D50 particle size is 16 μm.

[0039] Secondary granular graphitized material is obtained by mixing needle coke as aggregate and asphalt as binder, followed by crushing, granulation, carbonization, shaping, graphitization, sieving and demagnetization. Its D50 particle size is 14μm; the weight of asphalt is 9% of the weight of needle coke.

[0040] Comparative Example 1

[0041] An artificial graphite anode material comprises: single-particle graphitized material (D50 particle size of 15.5 μm) and secondary-particle graphitized material (D50 particle size of 13 μm); the weight ratio of single-particle graphitized material to secondary-particle graphitized material is 2:3. Wherein:

[0042] Single-particle graphitized material is obtained by using needle coke as aggregate, coarsely crushing the needle coke to a D50 particle size ≤ 5 mm, and then grinding, carbonizing, shaping, graphitizing, and sieving to remove magnetism. Its D50 particle size is 15.5 μm. The carbonization temperature is 700℃, the carbonization time is 8 h, and it is cooled to below 50℃ before shaping.

[0043] Secondary granular graphitized material is obtained by mixing needle coke as aggregate and asphalt as binder, followed by crushing, granulation, carbonization, shaping, graphitization, sieving and demagnetization. Its D50 particle size is 13μm; the weight of asphalt is 12% of the weight of needle coke.

[0044] Comparative Example 2

[0045] An artificial graphite anode material comprises: pre-carbonized modified single-particle graphitized material (D50 particle size of 15.5 μm) and secondary-particle graphitized material (D50 particle size of 13 μm); the weight ratio of the pre-carbonized modified single-particle graphitized material to the secondary-particle graphitized material is 2:3. Wherein:

[0046] The pre-carbonized modified single-particle graphitized material is identical to Example 1 in all steps and parameters except that the pre-carbonization temperature is changed from 700°C in Example 1 to 600°C.

[0047] The secondary particulate graphitized material is the same as in Example 1.

[0048] Using the artificial graphite obtained in Examples 1-5 and Comparative Examples 1-2 as negative electrode materials, button batteries were assembled, and their electrochemical performance was tested. The test results are shown in Table 1 below:

[0049] Table 1. Electrochemical performance test results

[0050] Example 1 1.106 355.4 375.1 94.75 Example 2 1.091 353.4 374.1 94.47 Example 3 1.043 348.0 371.3 93.72 Example 4 1.067 350.7 374.1 93.74 Example 5 1.004 346.9 370.5 93.63 Comparative Example 1 0.900 343.7 374.7 91.73 Comparative Example 2 0.906 341.9 374.0 91.41

[0051] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A synthetic graphite anode material, characterized in that, include: Pre-carbonized modified single-particle graphitized material and secondary-particle graphitized material; the weight ratio of pre-carbonized modified single-particle graphitized material to secondary-particle graphitized material is 1-3:3-5. The pre-carbonized modified single-particle graphitized material is obtained by coarsely crushing the aggregate, pre-carbonizing it at 700-750℃ for 5-15 hours, and then grinding, shaping, and graphitizing it; the aggregate is needle coke.

2. The artificial graphite anode material according to claim 1, characterized in that, The weight ratio of pre-carbonized modified single-particle graphitized material to secondary-particle graphitized material is 2:

3.

3. The artificial graphite anode material according to claim 1 or 2, characterized in that, The D50 particle size of the pre-carbonized modified single-particle graphitized material is 15-17 μm; the D50 particle size of the secondary-particle graphitized material is 12-14 μm.

4. The artificial graphite anode material according to claim 1 or 2, characterized in that, The pre-carbonization temperature is 700℃.

5. The artificial graphite anode material according to claim 1 or 2, characterized in that, Before pre-carbonization, the aggregate is coarsely crushed to a D50 particle size ≤ 5mm.

6. The artificial graphite anode material according to claim 1 or 2, characterized in that, Secondary granular graphitized materials are obtained by mixing aggregates and binders, followed by crushing, granulation, carbonization, shaping, and graphitization.

7. The artificial graphite anode material according to claim 6, characterized in that, The binder is asphalt.

8. The artificial graphite anode material according to claim 6, characterized in that, The amount of binder used is 9-12% of the weight of the aggregate.

9. The artificial graphite anode material according to claim 6, characterized in that, The amount of binder is 12% of the weight of the aggregate.