Acetylene carbon black with high capacity retention rate and preparation method and application thereof

Abstract

The invention belongs to the technical field of lithium batteries, and particularly relates to acetylene carbon black with a high capacity retention ratio and a preparation method and application thereof. The invention provides a preparation method of acetylene carbon black with high capacity retention ratio, which comprises the following steps: introducing benzene and acetylene into a reactor for reaction to obtain acetylene carbon black, the volume ratio of the benzene to the acetylene is 1: (2-5). By controlling the benzyne ratio, the generated acetylene carbon black has raised sawtooth surface defects, the bonding strength among the acetylene carbon black, an adhesive and an active substance is enhanced, the electrolyte consumption caused by SEI membrane breaking due to volume expansion possibly caused in the active substance circulation process is relieved, and the service life of the electrolyte is prolonged. And the probability of mutual shedding between the active substance and the conductive agent is also reduced. The capacity retention ratio of the acetylene carbon black prepared by the invention in a lithium ion battery is far higher than that of Super P and other conductive carbon black.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium batteries, and particularly relates to an acetylene carbon black with a high capacity retention rate, a preparation method thereof, and an application thereof. Background Art

[0002] In recent years, problems such as energy shortage and environmental pollution have become increasingly serious, and the research on new energy has become a social hotspot. Lithium-ion batteries, with their excellent energy density, no memory effect, environmental friendliness, and long cycle characteristics, have quickly occupied the dominant position in the market and are widely used in many fields such as electric vehicles, large-scale energy storage power stations, and even consumer electronics products.

[0003] However, the conductivity of the active materials of the positive and negative electrodes of most batteries themselves cannot meet the requirements in the batteries, and it is necessary to add conductive additives to improve the conductivity of the active materials. In this context, conductive carbon black, as a conductive agent with high conductivity, chemical inertness, and low cost, has extremely important value in the application of new energy batteries.

[0004] However, the capacity retention rate of the existing conductive carbon black in lithium-ion batteries needs to be improved. Therefore, it is necessary to obtain a conductive carbon black with a higher capacity retention rate. Summary of the Invention

[0005] The purpose of the present invention is to provide an acetylene carbon black with a high capacity retention rate, a preparation method thereof, and an application thereof.

[0006] In order to achieve the above purpose, the present invention provides the following technical solutions:

[0007] The present invention provides a preparation method of an acetylene carbon black with a high capacity retention rate, comprising the following steps:

[0008] Pass benzene and acetylene into a reactor for reaction to obtain the acetylene carbon black;

[0009] The volume ratio of the benzene to the acetylene is 1:2 to 5.

[0010] Preferably, the feeding amount of the acetylene is 100 to 200 m 3 / h.

[0011] Preferably, the acetylene is prepared by a preparation method comprising: mixing calcium carbide and water and carrying out a hydrolysis reaction to obtain the acetylene.

[0012] Preferably, the mass ratio of the calcium carbide to the water is 1:15 to 30.

[0013] Preferably, the temperature of the reaction is 1200 to 1700 °C.

[0014] Preferably, after the reaction, the obtained product is successively cooled, pressed, and magnetically separated.

[0015] The present invention also provides acetylene black prepared by the preparation method described in the above technical solution, and the surface of the acetylene black has a convex serrated structure.

[0016] Preferably, the ash content of the acetylene black is <0.1%.

[0017] The present invention also provides the application of the acetylene black described in the above technical solution in lithium batteries.

[0018] The present invention provides a preparation method of acetylene black with a high capacity retention rate, including the following steps: introducing benzene and acetylene into a reactor for reaction to obtain the acetylene black; the volume ratio of benzene to acetylene is 1:2 - 5. By controlling the benzene-acetylene ratio, the generated acetylene black has convex serrated surface defects, enhancing the bonding strength between the acetylene black, the binder, and the active material. This not only slows down the electrolyte consumption caused by the volume expansion that may occur during the cycling of the active material and the resulting fragmentation of the SEI film but also reduces the probability of mutual detachment between the active material and the conductive agent. As a result, the capacity retention rate of the acetylene black prepared by the present invention in lithium-ion batteries is much higher than that of other conductive carbons such as SuperP. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic flow chart of the preparation method provided by the present invention;

[0020] Figure 2 is a scanning electron microscope image of the acetylene black obtained in Examples 1 - 4 and the carbon black in Comparative Example 1;

[0021] Figure 3 is a transmission electron microscope image of the acetylene black obtained in Examples 1 - 4 and the carbon black in Comparative Example 1;

[0022] Figure 4 is a cycling performance curve of the batteries assembled with the acetylene black obtained in Examples 2 - 4 and the carbon black in Comparative Example 1;

[0023] Figure 5 is a SEM image of the positive electrode surface after 200 cycles of the battery assembled in Test Example 5;

[0024] Figure 6 is a cross-sectional SEM image of the positive electrode after 200 cycles of the battery assembled in Test Example 5. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The present invention provides a preparation method of acetylene black with a high capacity retention rate, including the following steps:

[0026] Benzene and acetylene are introduced into a reactor for reaction to obtain the acetylene black.

[0027] The volume ratio of the benzene to the acetylene is 1:2 to 5.

[0028] In the present invention, the acetylene is preferably prepared, and the preparation method preferably includes: mixing calcium carbide and water, and performing a hydrolysis reaction to obtain the acetylene. In the present invention, the mass ratio of the calcium carbide to the water is preferably 1:15 to 30. The present invention has no special limitation on the process of the hydrolysis reaction, and the process well-known to those skilled in the art can be adopted.

[0029] In the present invention, the volume ratio of the benzene to the acetylene is preferably 1:2 to 5, specifically it can be 1:2, 1:3, 1:4, 1:5. In the present invention, the feeding amount of the acetylene is preferably 100 to 200 m 3 / h. In the present invention, the benzene is preferably introduced into the reactor in the form of benzene vapor.

[0030] In the present invention, the temperature of the reaction is preferably 1200 to 1700 °C, specifically it can be 1200 °C, 1250 °C, 1300 °C, 1350 °C, 1400 °C, 1450 °C, 1500 °C, 1500 °C, 1600 °C, 1650 °C, 1700 °C. The temperature used for preparing the acetylene black in the present invention is between 1200 and 1700 °C, which is lower than the temperature of the known carbon black production process (usually above 1800 °C), with lower energy consumption and reduced carbon emissions.

[0031] In the present invention, after the reaction, it preferably further includes successively cooling, pressing, and magnetic separating the obtained product; the pressing is preferably performed in a vacuum stirring furnace.

[0032] Figure 1 It is a process schematic diagram of the preparation method provided by the present invention.

[0033] The present invention also provides acetylene black prepared by the preparation method described in the above technical solution, and the surface of the acetylene black has a convex serrated structure.

[0034] In the present invention, the ash content (825 °C) of the acetylene black is preferably <0.1%.

[0035] The present invention also provides the application of the acetylene black described in the above technical solution in lithium batteries.

[0036] Unless otherwise specified, the materials and equipment used in the present invention are all commercially available products in the art.

[0037] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0038] Example 1

[0039] Mix calcium carbide and water with a mass ratio of 1:15, and carry out a hydrolysis reaction to obtain acetylene;

[0040] Introduce the obtained acetylene and benzene vapor into a reactor, where the feeding amount of acetylene is 200 m 3 / h, and the volume ratio of benzene vapor to acetylene is 1:5. React at 1550 °C. After cooling the obtained product, introduce it into a vacuum stirring furnace for pressing, and then carry out magnetic separation to obtain acetylene black (denoted as Huahao 01).

[0041] Example 2

[0042] Mix calcium carbide and water with a mass ratio of 1:15, and carry out a hydrolysis reaction to obtain acetylene;

[0043] Introduce the obtained acetylene and benzene vapor into a reactor, where the feeding amount of acetylene is 200 m 3 / h, and the volume ratio of benzene vapor to acetylene is 1:5. React at 1450 °C. After cooling the obtained product, introduce it into a vacuum stirring furnace for pressing, and then carry out magnetic separation to obtain acetylene black (denoted as Huahao 02).

[0044] Example 3

[0045] Mix calcium carbide and water with a mass ratio of 1:15, and carry out a hydrolysis reaction to obtain acetylene;

[0046] Introduce the obtained acetylene and benzene vapor into a reactor, where the feeding amount of acetylene is 200 m 3 / h, and the volume ratio of benzene vapor to acetylene is 1:5. React at 1400 °C. After cooling the obtained product, introduce it into a vacuum stirring furnace for pressing, and then carry out magnetic separation to obtain acetylene black (denoted as Huahao 03).

[0047] Example 4

[0048] Mix calcium carbide and water with a mass ratio of 1:15, and carry out a hydrolysis reaction to obtain acetylene;

[0049] Introduce the obtained acetylene and benzene vapor into a reactor, where the feeding amount of acetylene is 200 m 3 / h, the volume ratio of benzene vapor to acetylene is 1:5, and the reaction is carried out at 1500 °C. After cooling the obtained product, it is introduced into a vacuum stirring furnace for pressing, and then magnetic separation is carried out to obtain acetylene black (denoted as Huahao 04).

[0050] Comparative Example 1

[0051] Commercially available SuperP, model number MA-EN-CO-0005.

[0052] Performance Test

[0053] Test Example 1

[0054] The physicochemical property characterizations of the acetylene black obtained in Examples 1 to 4 and the carbon black in Comparative Example 1 are shown in Table 1;

[0055] Table 1 Physicochemical property characterizations of the acetylene black obtained in the examples and the carbon black in the comparative example

[0056] unit Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Oil absorption value <![CDATA[10 -5 m 3 / kg]]> 281.5 263.5 266 292 286.4 Specific surface area <![CDATA[m 2 / g]]> 63.0 62.8 77.0 85.0 63.4 Iodine absorption value g / kg 88.0 90.0 100.0 105.0 68.5 Ash content (825 °C) ％ 0.08 0.09 0.02 0.05 0.11 Added or subtracted heat ％ 0.49 0.25 0.26 0.13 0.12 Particle size nm 25±5 35±5 40±5 15±5 50±5

[0057] As can be seen from Table 1, the acetylene black obtained in the present invention has less ash content, and the particle size can be adjusted from 10 nm to 45 nm.

[0058] Test Example 2

[0059] Figure 2 Scanning electron microscope images of the acetylene black obtained in Examples 1 to 4 and the carbon black in Comparative Example 1, where Figure 2 a is Example 1, b is Example 2, c is Example 3, d is Example 4, and e is Comparative Example 1;

[0060] From Figure 2 it can be seen that the primary structure of the acetylene black obtained in the present invention generally presents a chain structure, which can form a chain-like conductive structure with the active material, contributing to the improvement of the conductivity of the active material.

[0061] Test Example 3

[0062] Figure 3 Transmission electron microscope images of the acetylene black obtained in Examples 1 to 4 and the carbon black in Comparative Example 1, where Figure 3 a is Example 1, b is Example 2, c is Example 3, d is Example 4, and e is Comparative Example 1;

[0063] From Figure 3 it can be seen that the edges of the acetylene black of Huahao 01, Huahao 02, Huahao 03, and Huahao 04 present a relatively irregular angular state, while the outer layer of SuperP presents a regular graphite-like layer with relatively smooth edges.

[0064] Test Example 4

[0065] The conductivity of the acetylene black obtained in Examples 1 to 4 and the carbon black in Comparative Example 1 was tested (four-probe resistance test), and the test results are shown in Table 2;

[0066] Table 2 Conductivity of acetylene black obtained in Examples 1 to 4 and carbon black in Comparative Example 1

[0067] Huahao 01 Huahao 02 Huahao 03 Huahao 04 Comparative Example 1 Conductivity S / cm 0.500 1.111 0.4764 0.4545 3.333

[0068] As can be seen from Table 2, the conductivity of Huahao 02, Huahao 03, and Huahao 04 is slightly lower than that of Super P. This may be because surface defects will disrupt the conjugated state of the surface graphite-like layers to a certain extent, thus reducing the conductivity of carbon black to a certain extent.

[0069] Test Example 5

[0070] The acetylene black obtained in Examples 2 to 4 and the carbon black in Comparative Example 1 were used as conductive agents to assemble a lithium battery for testing;

[0071] Assembly process:

[0072] Lithium iron phosphate, polyvinylidene fluoride, and a conductive agent were ball-milled and dispersed in N-methylpyrrolidone (400 r / min) according to a mass ratio of 8:1:1. Then, the mixed slurry was coated on aluminum foil and dried to obtain a positive electrode (no rolling or any other treatment was performed on the aluminum foil, that is, only coating); a lithium metal sheet was used as the negative electrode, a 1 M lithium hexafluorophosphate solution was used as the electrolyte, and a Celgard 2400 separator was used as the separator to assemble a button cell.

[0073] Figure 4 For the batteries assembled with the acetylene black obtained in Examples 1 to 4 and the carbon black obtained in Comparative Example 1 (H300 is Huahao 02, H400 is Huahao 03, and H435 is Huahao 04), the cycle performance curves are shown, and the test results of the capacity retention rate are shown in Table 3;

[0074] Table 3 Capacity retention rate of batteries assembled with acetylene black obtained in Examples and carbon black in Comparative Examples

[0075] Huahao 02 Huahao 03 Huahao 04 Comparative Example 1 Retention rate of 200-cycle capacity 90.4％ 88.9％ 74.6％ 18.3％

[0076] From Figure 4 and Table 3, it can be seen that the acetylene black obtained in the examples of the present invention is superior to the carbon black in the comparative examples in terms of the retention rate of the cycle capacity.

[0077] Test Example 6

[0078] For the batteries assembled in Test Example 5, after 200 cycles of testing, the surface of the positive electrode was detected by scanning electron microscopy, and the obtained SEM images are as Figure 5 shown;

[0079] Figure 5 For Example 2, a; for Example 3, b; and for Comparative Example 1, c. It can be seen that after adding the acetylene black prepared by the present invention into lithium iron phosphate and cycling 200 times, the conductive domains (Conductive Domain refers to the local regions with high conductivity in the material, usually composed of conductive phases or conductive channels. These regions form a conductive network in the insulating or semi-conductive matrix, endowing the overall conductivity of the material) are more uniform, and the combination with lithium iron phosphate is closer.

[0080] For the battery assembled in Test Example 5, after performing the 200-cycle test, the cross-section of the positive electrode was detected by scanning electron microscopy, and the obtained SEM images are as Figure 6 shown;

[0081] Figure 6 For a and c, Example 2; for b and d, Comparative Example 1. It can be seen that the morphology of the bonded body after cycling of Huahao 02 is closer than that of Super P after cycling, showing a cluster shape, while Super P is looser compared to Huahao 02.

[0082] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, rather than all embodiments. Other embodiments can be obtained based on these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing acetylene carbon black with high capacity retention rate, characterized in that: The following steps are involved: Passing benzene and acetylene into a reactor for reaction to obtain the acetylene carbon black; The volume ratio of benzene to acetylene is 1:2-5.

2. The preparation method according to claim 1, characterized in that: The amount of acetylene introduced is 100-200m 3 / h.

3. The preparation method according to claim 1, characterized in that: The acetylene is obtained by preparation, and the preparation method comprises: mixing calcium carbide and water, and performing a hydrolysis reaction to obtain the acetylene.

4. The preparation method according to claim 3, characterized in that: The mass ratio of calcium carbide to water is 1:15-30.

5. The preparation method according to claim 1, characterized in that: The reaction temperature is 1200-1700°C.

6. The preparation method according to claim 1, characterized in that: After the reaction, the obtained product is sequentially cooled, pressed and magnetically separated.

7. The acetylene carbon black prepared by the preparation method according to any one of claims 1 to 6, characterized in that: The surface of the acetylene carbon black has a protruding sawtooth structure.

8. The acetylene black according to claim 7, characterized in that The ash content of the acetylene carbon black is less than 0.1%.

9. Use of the acetylene black according to claim 7 or 8 in lithium batteries.

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