A secondary particle artificial graphite material and a method for manufacturing the same

Abstract

The application discloses a kind of secondary particle artificial graphite materials and preparation method thereof.The preparation method includes the following steps: (1) the raw material coke is granulated, and semi-finished product 1 is prepared;The particle size ratio D of semi-finished product 1 is 0.3-0.7 v 50 is 7-100 μm;(2) semi-finished product 1 is depolymerized and classified, and semi-finished product 2 is prepared;The particle size ratio D of semi-finished product 2 and the semi-finished product 1 is 0.3-0.7;(3) semi-finished product 2 is graphitized, and secondary particle artificial graphite material is prepared.The preparation method of the application effectively improves the tap density of secondary particle artificial graphite material, and improves the processing performance as negative electrode material subsequently;And preparation method is simple, easy to operate, yield is high, cost is low, easy to realize industrial production, without adding other components.

Description

Technical Field

[0001] This invention relates to a secondary particulate artificial graphite material and its preparation method. Background Technology

[0002] Artificial graphite materials are classified into primary particles and secondary particles according to their structural differences, depending on their application fields and usage requirements. Among them, secondary particles have always had some problems, one of which is low tap density. In practical use, the low tap density of artificial graphite materials has an adverse effect on the subsequent slurry bonding process in battery manufacturing. Therefore, battery manufacturers hope to improve the tap density to improve the processing characteristics of the material itself.

[0003] Currently, there are limited methods on the market for improving the tap density of artificial graphite materials, and even fewer methods specifically for improving the tap density of "secondary artificial graphite particles." Generally, this is achieved by shaping or mixing high-tap-density primary particles with raw materials, semi-finished products, or finished products. However, this approach has limited effectiveness and significant side effects. For example, while primary particles generally have a higher tap density than secondary particles, primary particles suffer from low energy density and large specific surface area. Mixing primary and secondary particles, although increasing the tap density, results in a loss of energy density. Therefore, significantly improving the tap density of secondary artificial graphite particles has become particularly urgent and important.

[0004] CN112758921B increases the tap density of the mixture by mixing the materials, not by increasing the tap density of the artificial graphite itself, and the increase is limited. CN112713264A discloses a method for preparing artificial graphite anode materials by reusing graphite fragments. Although it mentions the effect of high tap density, its focus is on how to reuse the graphite fragments, and the tap density is consistently below 1 g / cm³. 3 the following. Summary of the Invention

[0005] The problem solved by this invention is to overcome the low tap density of secondary particle artificial graphite materials in the prior art, and to provide a secondary particle artificial graphite material and its preparation method. The preparation method of this invention effectively improves the tap density of the secondary particle artificial graphite material, thereby improving its subsequent processing performance as a negative electrode material; moreover, the preparation method is simple, easy to operate, has a high yield, low cost, and is easily scalable for industrial production, requiring no addition of other components.

[0006] In the field of preparing artificial graphite materials, technicians typically perform deagglomeration operations based on the required particle size range. During their research, the inventors discovered that because secondary particle artificial graphite contains numerous voids during the bonding process, deagglomeration and classification of the material exposes these voids. The inventors creatively improved the particle exposure rate by controlling the particle size of different intermediates, thereby increasing the tap density.

[0007] The present invention mainly solves the above problems through the following technical solutions.

[0008] This invention provides a method for preparing secondary particulate artificial graphite material, which includes the following steps:

[0009] (1) The raw coke is subjected to secondary granulation to obtain semi-finished product 1; the D of the semi-finished product 1 is... v 50 is 7–100 μm;

[0010] (2) Depolymerize and classify semi-finished product 1 to obtain semi-finished product 2; the particle size ratio D of semi-finished product 2 and semi-finished product 1 is 0.3 to 0.7.

[0011] (3) The semi-finished product 2 is graphitized to obtain secondary granular artificial graphite material.

[0012] In step (1), the raw material coke may be needle coke and / or petroleum coke.

[0013] In step (1), the tap density of the raw coke can be greater than 0.40 g / cm³. 3 The preferred value is 0.40–0.70 g / cm³. 3 For example, 0.60 g / cm³ 3 .

[0014] In step (1), the particle size of the raw coke can be 7 to 15 μm, for example 9 μm.

[0015] In step (1), conventional pulverization operations can be performed before the secondary granulation.

[0016] In step (1), the secondary granulation operation can be conventional in the art, preferably involving mixing the raw coke with a binder and then heat-treating it. The binder can be asphalt and / or resin.

[0017] The ratio of the raw coke to the binder can be conventional in the art; preferably, the amount of binder is 2-40%, for example 10% or 16.7%, where % refers to the mass percentage of the binder in the total amount of raw materials.

[0018] Wherein, the adhesive's D v 50 can be 1 to 10 μm, for example 1.5 μm, 3 μm, 7 μm or 9 μm.

[0019] The preferred temperature for the heat treatment is 400–600°C, for example, 600°C.

[0020] The heat treatment time is preferably 500 to 700 minutes, for example, 600 minutes.

[0021] In step (1), the D of the semi-finished product 1 v 50 is preferably 20–60 μm, for example 26 μm, 30 μm, 40 μm, or 48 μm. Those skilled in the art will know that D v The larger the value of 50, the easier it is to manufacture. However, in practice, to achieve better performance, D is often used. v For materials smaller than 30μm, the solution proposed in this application can increase the upper limit of the material particle size and broaden its practical processing applications.

[0022] In step (2), the depolymerization and classification operation can be conventional in the art; preferably, a mechanical mill is used for depolymerization and classification.

[0023] In step (2), the particle size ratio D of the semi-finished product 2 and the semi-finished product 1 is preferably 0.3 to 0.5, for example, 0.3, 0.4, or 0.5. D refers to the particle size distribution of semi-finished product 2. v 50 and semi-finished product 1 of D v The ratio of 50.

[0024] In step (2), the D of the semi-finished product 2 v The preferred value for 50 is 10-30 μm, such as 12 μm, 13 μm, 15 μm, 16 μm, 20 μm, 24 μm or 28 μm.

[0025] In step (3), the graphitization process can be a conventional operation in the field.

[0026] The preferred temperature for the graphitization treatment is 3000–3400°C, for example, 3200°C.

[0027] The graphitization treatment time is preferably 24 to 72 hours, for example, 48 hours.

[0028] In some preferred embodiments, the preparation method of the secondary particulate artificial graphite material includes the following steps:

[0029] (1) The raw coke is mixed with a binder and heat-treated to obtain semi-finished product 1; the tap density of the raw coke is 0.40-0.70 g / cm³. 3 The amount of the adhesive used is 2-40%; the D of the semi-finished product 1 v50 is 20-60 μm; the heat treatment temperature is 400-600 °C; the heat treatment time is 500-700 min;

[0030] (2) Depolymerize and classify semi-finished product 1 to obtain semi-finished product 2; the particle size ratio D of semi-finished product 2 and semi-finished product 1 is 0.3 to 0.5;

[0031] (3) The semi-finished product 2 is graphitized to obtain secondary granular artificial graphite material; the graphitization temperature is 3000-3400℃ and the graphitization time is 24-72h.

[0032] The present invention also provides a secondary particulate artificial graphite material, which is prepared by the above preparation method.

[0033] In this invention, the tap density of the secondary particle artificial graphite material can be 1.0–1.35 g / cm³. 3 For example, 1.01 g / cm³ 3 1.19 g / cm 3 1.21 g / cm 3 1.22g / cm 3 1.27g / cm 3 1.29g / cm 3 Or 1.31 g / cm 3 .

[0034] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0035] The reagents and raw materials used in this invention are all commercially available.

[0036] The positive and progressive effects of this invention are as follows:

[0037] This invention starts by adjusting the structure of graphite itself. By controlling the particle size of intermediate materials, it effectively improves the tap density of secondary particle artificial graphite materials, thereby enhancing their processing performance as a negative electrode material. Furthermore, the preparation method is simple, easy to operate, has a high yield, low cost, and is easily scalable for industrial production, requiring no additional components. The secondary particle artificial graphite material obtained by this invention has a high tap density, reaching 1.0–1.35 g / cm³. 3 . Detailed Implementation

[0038] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0039] In the following examples and comparative examples, the asphalt was purchased from Liaoning Xinde New Material Technology Co., Ltd., and its softening point was 250°C.

[0040] The tap density involved in this invention is a conventional test item in the field. The test principle is to place a certain mass of artificial graphite powder particles in a specific container, vibrate them at a specific frequency for a certain period of time, and obtain the tap density by measuring the volume after vibration and dividing the sample mass by the volume.

[0041] Example 1

[0042] (1) The tapped density is 0.60 g / cm³. 3 Needle coke pulverized to D v 50 = 9μm. Mix it with D at a mass ratio of 100:20. v Asphalt with a particle size of 50 = 7 μm is mixed, heated, and then subjected to secondary granulation at 600℃ for 600 min to obtain semi-finished product 1. The particle size of semi-finished product 1 is controlled by adjusting the particle size of the asphalt. The D of semi-finished product 1... v 50 = 40μm;

[0043] (2) Semi-finished product 1 was depolymerized and classified using a mechanical mill to obtain semi-finished product 2; the D of semi-finished product 2... v 50 is 12μm, which means the particle size ratio D of semi-finished product 2 and semi-finished product 1 is 0.3;

[0044] (3) The semi-finished product 2 is subjected to graphitization treatment at a temperature of 3200℃ for 48 hours.

[0045] Secondary particulate artificial graphite was prepared, with a tap density of 1.21 g / cm³. 3 .

[0046] Example 2

[0047] (1) Same as step (1) in Example 1;

[0048] (2) Semi-finished product 1 was depolymerized and classified using a mechanical mill to obtain semi-finished product 2; the D of semi-finished product 2... v 50 is 16μm, which means the particle size ratio D of semi-finished product 2 and semi-finished product 1 is 0.4;

[0049] (3) is the same as step (3) in Example 1.

[0050] Secondary particulate artificial graphite was prepared, with a tap density of 1.27 g / cm³. 3 .

[0051] Example 3

[0052] (1) Same as step (1) in Example 1;

[0053] (2) Semi-finished product 1 was depolymerized and classified using a mechanical mill to obtain semi-finished product 2; the D of semi-finished product 2... v 50 is 20μm, which means the particle size ratio D of semi-finished product 2 and semi-finished product 1 is 0.5;

[0054] (3) is the same as step (3) in Example 1;

[0055] Secondary particulate artificial graphite was prepared, with a tap density of 1.31 g / cm³. 3 .

[0056] Example 4

[0057] (1) Same as step (1) in Example 1;

[0058] (2) Semi-finished product 1 was depolymerized and classified using a mechanical mill to obtain semi-finished product 2; the D of semi-finished product 2... v 50 is 28μm, which means the particle size ratio D of semi-finished product 2 and semi-finished product 1 is 0.7;

[0059] (3) is the same as step (3) in Example 1;

[0060] Secondary particulate artificial graphite was prepared, with a tap density of 1.22 g / cm³. 3 .

[0061] Example 5

[0062] (1) The tapped density is 0.60 g / cm³. 3 Needle coke pulverized to D v 50 = 9μm. Mix it with D at a mass ratio of 100:20. v Asphalt with a particle size of 50 = 3 μm is mixed, heated, and then subjected to secondary granulation at 600℃ for 600 min to obtain semi-finished product 1; the D of semi-finished product 1... v 50 = 30μm;

[0063] (2) Semi-finished product 1 was depolymerized and classified using a mechanical mill to obtain semi-finished product 2; the D of semi-finished product 2... v 50 is 15μm, which means the particle size ratio D between semi-finished product 2 and semi-finished product 1 is 0.5;

[0064] (3) is the same as step (3) in Example 1;

[0065] Secondary particulate artificial graphite was prepared, with a tap density of 1.29 g / cm³. 3 .

[0066] Example 6

[0067] (1) The tapped density is 0.60 g / cm³. 3 Needle coke pulverized to Dv 50 = 9μm. Mix it with D at a mass ratio of 100:20. v Asphalt with a particle size of 50 = 9 μm is mixed, heated, and then subjected to secondary granulation at 600℃ for 600 min to obtain semi-finished product 1; the D of semi-finished product 1... v 50 = 48μm;

[0068] (2) Semi-finished product 1 was depolymerized and classified using a mechanical mill to obtain semi-finished product 2; the D of semi-finished product 2... v 50 is 24μm, which means the particle size ratio D of semi-finished product 2 and semi-finished product 1 is 0.5;

[0069] (3) is the same as step (3) in Example 1;

[0070] Secondary particulate artificial graphite was prepared, with a tap density of 1.19 g / cm³. 3 .

[0071] Example 7

[0072] (1) The tapped density is 0.60 g / cm³. 3 Needle coke pulverized to D v 50 = 9μm. Mix it with D at a mass ratio of 100:20. v Asphalt with a particle size of 50 = 1.5 μm is mixed, heated, and then subjected to secondary granulation at 600℃ for 600 min to obtain semi-finished product 1; the D of semi-finished product 1... v 50 = 26 μm;

[0073] (2) Semi-finished product 1 was depolymerized and classified using a mechanical mill to obtain semi-finished product 2; the D of semi-finished product 2... v 50 is 13μm, which means the particle size ratio D of semi-finished product 2 and semi-finished product 1 is 0.5;

[0074] (3) is the same as step (3) in Example 1;

[0075] Secondary particulate artificial graphite was prepared, with a tap density of 1.01 g / cm³. 3 .

[0076] Comparative Example 1

[0077] (1) Same as step (1) in Example 1;

[0078] (2) Semi-finished product 1 was depolymerized and classified using a mechanical mill to obtain semi-finished product 2; the D of semi-finished product 2... v 50 is 3.6μm, which means that the particle size ratio D of semi-finished product 2 and semi-finished product 1 is 0.09;

[0079] (3) is the same as step (3) in Example 1;

[0080] Secondary particulate artificial graphite was prepared, with a tap density of 0.85 g / cm³. 3 .

[0081] Comparative Example 2

[0082] (1) Same as step (1) in Example 1;

[0083] (2) Semi-finished product 1 was depolymerized and classified using a mechanical mill to obtain semi-finished product 2; the D of semi-finished product 2... v 50 is 36μm, which means the particle size ratio D of semi-finished product 2 and semi-finished product 1 is 0.9;

[0084] (3) is the same as step (3) in Example 1;

[0085] Secondary particulate artificial graphite was prepared, with a tap density of 0.86 g / cm³. 3 .

[0086] Comparative Example 3

[0087] (1) The tapped density is 0.60 g / cm³. 3 Needle coke pulverized to D v 50 = 9μm. Mix it with D at a mass ratio of 100:20. v Asphalt with a particle size of 50 = 20 μm is mixed, heated, and then subjected to secondary granulation at 600℃ for 600 min to obtain semi-finished product 1; the D of semi-finished product 1... v 50 = 120 μm;

[0088] (2) Semi-finished product 1 was depolymerized and classified using a mechanical mill to obtain semi-finished product 2; the D of semi-finished product 2... v 50 is 36μm, which means the particle size ratio D of semi-finished product 2 and semi-finished product 1 is 0.3;

[0089] (3) is the same as step (3) in Example 1;

[0090] Secondary particulate artificial graphite was prepared, with a tap density of 0.90 g / cm³. 3 .

[0091] Effect Example

[0092] The artificial graphite materials prepared in the above examples and comparative examples were subjected to a slurry treatment: polyvinylidene fluoride (PVDF) was dissolved in N-methylpyrrolidone (NMP) solvent, a conductive agent (SP) was added, and after stirring evenly, modified artificial graphite anode material (wherein, modified artificial graphite anode material: PVDF: NMP: SP = 95.5:1.5:1.5:1.5) was added, and the mixture was stirred evenly again to complete the slurry preparation.

[0093] After the obtained slurry is left to stand for 48 hours, observe the state of the slurry to see if sedimentation or stratification occurs.

[0094] The main parameters and properties of the secondary particulate artificial graphite materials prepared in the above embodiments and comparative examples are shown in Table 1.

[0095] Table 1

[0096]

[0097] According to Examples 1-4 and Comparative Examples 1-2, when the particle size of semi-finished product 1 is 40 μm, the particle size ratio D of semi-finished product 2 and semi-finished product 1 gradually increases, and the tap density increases accordingly. When the particle size ratio D is increased further after reaching a certain value, the tap density shows a decreasing trend. When the particle size ratio D of semi-finished product 2 and semi-finished product 1 is 0.5, the tap density is the highest.

[0098] According to Examples 3 and 5-7, when the particle size ratio D of semi-finished product 2 and semi-finished product 1 is 0.5, increasing the particle size of semi-finished product 1 within a certain range increases the tap density. When the particle size of semi-finished product 1 is increased further after reaching a certain value, the tap density decreases. The tap density is highest when the particle size of semi-finished product 1 is 40μm.

[0099] As can be seen from Example 1 and Comparative Example 3, when the particle size ratio D of semi-finished product 2 and semi-finished product 1 is 0.3, the tap density of semi-finished product 1 is low when the particle size exceeds the range of the present invention.

[0100] The experimental results show that comparative examples 1 to 3 all exhibited some sedimentation and relatively obvious stratification; examples 1 to 7 all showed a uniform state, indicating that increasing the tap density is beneficial to the preparation of the battery.

Claims

1. A method for preparing a secondary particulate artificial graphite material, characterized in that, It includes the following steps: (1) The raw coke is subjected to secondary granulation to obtain semi-finished product 1; the D of the semi-finished product 1 is... v 50 represents 30~40μm; (2) Depolymerize and classify semi-finished product 1 to obtain semi-finished product 2; the particle size ratio D of semi-finished product 2 and semi-finished product 1 is 0.4~0.5; the particle size ratio D of semi-finished product 2 is... v 50 represents 15~20μm; (3) The semi-finished product 2 is graphitized to obtain secondary granular artificial graphite material; In step (1), the particle size of the raw coke is 7~15μm; the tap density of the secondary particle artificial graphite material is 1.27~1.31g / cm³. 3 .

2. The method for preparing secondary particulate artificial graphite material as described in claim 1, characterized in that, In step (1), the D of the semi-finished product 1 v 50 represents 30μm or 40μm.

3. The method for preparing secondary particulate artificial graphite material as described in claim 1, characterized in that, In step (2), the particle size ratio D of the semi-finished product 2 and the semi-finished product 1 is 0.4 or 0.

5.

4. The method for preparing secondary particulate artificial graphite material as described in claim 1, characterized in that, In step (2), the D of the semi-finished product 2 v 50 represents 15μm, 16μm, or 20μm.

5. The method for preparing secondary particulate artificial graphite material as described in claim 1, characterized in that, In step (1), the raw material coke is needle coke and / or petroleum coke; And / or, in step (1), the tap density of the raw coke is greater than 0.40 g / cm³. 3 .

6. The method for preparing secondary particulate artificial graphite material as described in claim 5, characterized in that, In step (1), the tap density of the raw coke is 0.40~0.70 g / cm³. 3 ; And / or, in step (1), the particle size of the raw material coke is 9 μm.

7. The method for preparing secondary particulate artificial graphite material as described in claim 6, characterized in that, In step (1), the tap density of the raw coke is 0.60 g / cm³. 3 .

8. The method for preparing secondary particulate artificial graphite material as described in claim 1, characterized in that, In step (1), a crushing operation is performed before the secondary granulation; And / or, in step (1), the secondary granulation operation is to mix the raw material coke with the binder and heat treat it.

9. The method for preparing secondary particulate artificial graphite material as described in claim 8, characterized in that, The binder is preferably asphalt and / or resin.

10. The method for preparing secondary particulate artificial graphite material as described in claim 8, characterized in that, The amount of the adhesive used is 2-40%, where % refers to the mass percentage of the adhesive in the total amount of raw materials; And / or, the adhesive has a Dv50 of 3~7μm; And / or, the temperature of the heat treatment is 400~600℃; And / or, the heat treatment time is 500~700 min.

11. The method for preparing secondary particulate artificial graphite material as described in claim 10, characterized in that, The amount of adhesive used is 10%, where % refers to the mass percentage of the adhesive relative to the total amount of raw materials; And / or, the adhesive has a Dv50 of 3 μm or 7 μm; And / or, the heat treatment temperature is 600°C; And / or, the heat treatment time is 600 min.

12. The method for preparing secondary particulate artificial graphite material as described in claim 1, characterized in that, The temperature for the graphitization treatment is 3000~3400℃; And / or, the graphitization treatment time is 24~72h.

13. The method for preparing secondary particulate artificial graphite material as described in claim 12, characterized in that, The graphitization treatment temperature is 3200℃; And / or, the graphitization treatment time is 48 hours.

14. The method for preparing secondary particulate artificial graphite material as described in claim 1, characterized in that, It includes the following steps: (1) The raw coke is mixed with a binder and heat-treated to obtain semi-finished product 1; the tap density of the raw coke is 0.40~0.70 g / cm³. 3 The amount of the adhesive used is 2-40%; the D of the semi-finished product 1 v 50 is 30~40μm; the heat treatment temperature is 400~600℃; the heat treatment time is 500~700min; (2) Depolymerize and classify semi-finished product 1 to obtain semi-finished product 2; the particle size ratio D of semi-finished product 2 and semi-finished product 1 is 0.4~0.5; (3) The semi-finished product 2 is graphitized to obtain secondary granular artificial graphite material; the graphitization temperature is 3000~3400℃ and the graphitization time is 24~72h.

15. A secondary particle artificial graphite material, characterized in that, It is prepared by the method for preparing secondary particulate artificial graphite material as described in any one of claims 1 to 14.

16. The secondary particle artificial graphite material as described in claim 15, characterized in that, The tap density of the secondary particle artificial graphite material is 1.27 g / cm³. 3 1.29g / cm 3 Or 1.31 g / cm 3 .

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