Composite binder, graphite negative electrode material, preparation method of graphite negative electrode material, electrode and battery

Abstract

The invention discloses a composite binder, a graphite negative electrode material, a preparation method of the graphite negative electrode material, an electrode and a battery. The composite binder comprises asphalt and an inorganic nano anti-agglomeration agent, the inorganic nano anti-agglomeration agent is one or more of oxide, carbide, nitride, boride, silicide and silicate. The graphite negative electrode material prepared by adopting the composite binder disclosed by the invention is relatively uniform in particle size distribution and relatively high in yield of qualified products.

Description

Technical Field

[0001] This invention relates to a composite binder, a graphite anode material and its preparation method, an electrode and a battery. Background Technology

[0002] In the manufacturing process of graphite anode materials for lithium-ion batteries, asphalt is often used as a binder to bond and granulate the crushed raw coke in order to improve the performance of the anode material. The traditional granulation process usually involves directly mixing the crushed raw coke with a certain proportion of asphalt powder, and then melting the asphalt under the action of heating and shearing force to bind the raw coke particles, forming bonded secondary particles.

[0003] However, this process has a significant problem: because asphalt becomes more fluid and viscous after heating and melting, it can easily lead to excessive asphalt in localized areas. This causes excessive adhesion between the raw material coke particles, forming a large number of hard agglomerates with excessively large particle size or density. These excessively adhered large particles must be removed in the subsequent screening process, resulting in a reduced yield of qualified products and increased production costs. Furthermore, if these large particles are mixed into the finished product, they can also cause uneven coating, affecting the battery's rate performance and cycle life.

[0004] In existing technologies, mechanical crushing methods such as air jet mills are commonly used to process these large particles. However, this method is a post-processing step, which consumes a lot of energy and may destroy the already formed ideal spherical particles, leading to an increase in fine powder, which also affects the yield and product quality. For example, the depolymerization scheme for anode material agglomerates mentioned in patent CN 120600783A, which involves adding surfactants to the agglomerated material and then mechanically crushing and sieving it to form a complete coating layer, is essentially still a post-processing step.

[0005] Therefore, there is an urgent need for a granulation method that can reduce the formation of excessively bonded large particles at the source. Summary of the Invention

[0006] The technical problem this invention aims to solve is to overcome the shortcomings of existing technologies that use asphalt as a binder to bind and granulate raw coke, resulting in excessively large secondary particle sizes or numerous agglomerates, and requiring mechanical crushing, leading to a low yield of qualified products. This invention provides a composite binder, graphite anode material, its preparation method, electrode, and battery. The graphite anode material prepared using the composite binder of this invention has a more uniform particle size distribution and a higher yield of qualified products.

[0007] The present invention solves the above-mentioned technical problems through the following technical solution:

[0008] This invention provides a composite adhesive comprising asphalt and an inorganic nano-anti-agglomeration agent;

[0009] The inorganic nano-anti-agglomeration agent is one or more of oxides, carbides, nitrides, borides, silicides, and silicates.

[0010] In this invention, the type of asphalt can be selected according to conventional methods in the art, with petroleum asphalt being preferred.

[0011] In this invention, the particle size of the asphalt can be 2μm-15μm, preferably 3μm-10μm, for example 7μm.

[0012] In this invention, the softening point of the asphalt can be 100℃-300℃, preferably 150℃-250℃, for example 200℃ or 207℃.

[0013] In this invention, the coking value of the asphalt can be 30%-90%, preferably 40%-80%, for example 62.8%. The coking value refers to the content of non-volatile carbonaceous residue after calcining the asphalt in a tubular furnace at 900°C in the absence of air for 1 hour.

[0014] In a preferred embodiment, the asphalt is petroleum asphalt, the particle size of the asphalt is 7μm, the softening point is 207℃, and the coking value is 62.8%.

[0015] In this invention, the mass percentage of the asphalt can be 90%-99.5%, preferably 95%-99.5%, for example 95% or 98%. The mass percentage represents the mass percentage of asphalt in the composite binder.

[0016] In this invention, the oxide is preferably selected from metal oxides and / or non-metal oxides. The metal oxide preferably includes or is one or more of zinc oxide, magnesium oxide, zirconium oxide, and aluminum oxide, such as aluminum oxide. The non-metal oxide is preferably silicon dioxide.

[0017] In this invention, the carbide is preferably selected from silicon carbide and / or boron carbide.

[0018] In this invention, the nitride is preferably selected from one or more of silicon nitride, aluminum nitride, titanium nitride, and boron nitride.

[0019] In this invention, the boride is preferably selected from one or more of titanium diboride, zirconium diboride, and hafnium diboride.

[0020] In this invention, the inorganic nano-anti-agglomeration agent preferably includes or is silicon dioxide and / or aluminum oxide.

[0021] In this invention, the particle size of the inorganic nano anti-agglomeration agent can be 5-200 nm, preferably 10-100 nm, for example 10, 17, 20 or 40 nm.

[0022] In this invention, the specific surface area of ​​the inorganic nano-anti-agglomeration agent can be 10 m². 2 / g-400m 2 / g, preferably 80-200m 2 / g, for example 50, 93, 98, 10 or 190m 2 / g.

[0023] In a preferred embodiment, the inorganic nano-anti-agglomeration agent is nano-silica, the particle size of the inorganic nano-anti-agglomeration agent is 20 nm, and the specific surface area of ​​the inorganic nano-anti-agglomeration agent can be 93 m². 2 / g.

[0024] In a preferred embodiment, the inorganic nano-anti-agglomeration agent is nano-alumina, the particle size of the inorganic nano-anti-agglomeration agent is 17 nm, and the specific surface area of ​​the inorganic nano-anti-agglomeration agent is 98 m². 2 / g.

[0025] In a preferred embodiment, the inorganic nano-anti-agglomeration agent is nano-silica, the particle size of the inorganic nano-anti-agglomeration agent is 10 nm, and the specific surface area of ​​the inorganic nano-anti-agglomeration agent is 190 m². 2 / g.

[0026] In a preferred embodiment, the inorganic nano-anti-agglomeration agent is nano-silica, the particle size of the inorganic nano-anti-agglomeration agent is 40 nm, and the specific surface area of ​​the inorganic nano-anti-agglomeration agent is 50 m². 2 / g.

[0027] In this invention, the inorganic nano-anti-agglomeration agent can have a mass percentage of 0.5%-10%, preferably 0.5%-5%, for example 2% or 5%. The mass percentage represents the mass percentage of the inorganic nano-anti-agglomeration agent in the composite binder.

[0028] In a preferred embodiment, the composite binder comprises 98% asphalt and 2% inorganic nano-anti-agglomeration agent; the inorganic nano-anti-agglomeration agent is preferably nano-silica; the particle size of the inorganic nano-anti-agglomeration agent is preferably 20 nm, and the specific surface area of ​​the inorganic nano-anti-agglomeration agent is preferably 93 m². 2 / g.

[0029] In a preferred embodiment, the composite binder comprises 95% asphalt and 5% inorganic nano-anti-agglomeration agent; the inorganic nano-anti-agglomeration agent is preferably nano-silica; the particle size of the inorganic nano-anti-agglomeration agent is preferably 20 nm, and the specific surface area of ​​the inorganic nano-anti-agglomeration agent is preferably 93 m². 2 / g.

[0030] In a preferred embodiment, the composite binder comprises 98% asphalt and 2% inorganic nano-anti-agglomeration agent; the inorganic nano-anti-agglomeration agent is preferably nano-alumina; the particle size of the inorganic nano-anti-agglomeration agent is preferably 17 nm, and the specific surface area of ​​the inorganic nano-anti-agglomeration agent is preferably 98 m². 2 / g.

[0031] In a preferred embodiment, the composite binder comprises 98% asphalt and 2% inorganic nano-anti-agglomeration agent; the inorganic nano-anti-agglomeration agent is preferably nano-silica; the particle size of the inorganic nano-anti-agglomeration agent is preferably 10 nm, and the specific surface area of ​​the inorganic nano-anti-agglomeration agent is preferably 190 m². 2 / g.

[0032] In a preferred embodiment, the composite binder comprises 98% asphalt and 2% inorganic nano-anti-agglomeration agent; the inorganic nano-anti-agglomeration agent is preferably nano-silica; the particle size of the inorganic nano-anti-agglomeration agent is preferably 40 nm, and the specific surface area of ​​the inorganic nano-anti-agglomeration agent is preferably 50 m². 2 / g.

[0033] The present invention also provides a method for preparing the composite adhesive as described above, which includes the following steps: mixing the asphalt and the inorganic nano anti-agglomeration agent.

[0034] In this invention, the mixing device can be conventional in the art, such as a mixer.

[0035] In this invention, the mixing time can be 1h-4h, for example 2h.

[0036] The present invention also provides a method for preparing a graphite anode material, which includes the following steps: granulating a mixture comprising raw material coke and the composite binder to obtain the graphite anode material.

[0037] In this invention, the type of raw coke is common in the art, including one or more of petroleum coke, pitch coke, and needle coke, such as needle coke.

[0038] In this invention, the true density of the raw coke can be 1.5-2.5 g / cm³. 3 For example, 1.98 g / cm³ 3 .

[0039] In this invention, the ash content of the raw coke can be <0.5%, for example 0.2%.

[0040] In this invention, the moisture content of the raw coke can be <4%, for example 2%.

[0041] In this invention, the volatile matter content of the raw material coke can be 2%-10%, for example 7%.

[0042] In this invention, the D50 of the raw material coke can be 3μm-15μm, for example 7 or 9μm.

[0043] In this invention, the mass ratio of the raw material coke to the composite binder can be (3-49):1, preferably (5-20):1, for example 10:1.

[0044] In this invention, the mixture of the raw material coke and the composite binder is preferably obtained by mixing the raw material coke and the composite binder.

[0045] The mixing equipment can be conventional in the art, such as a mixer. The mixing time is preferably 1-2 hours, for example, 90 minutes. The mixing temperature is preferably room temperature, generally 25-30°C. Stirring is preferably also performed during mixing. The stirring rate is preferably 5-40 Hz, for example, 15 Hz.

[0046] In this invention, the granulation equipment can be conventional in the art, such as a granulation reactor.

[0047] In this invention, the granulation temperature can be higher than the softening point of the asphalt, preferably 400-700℃, for example 600℃.

[0048] In this invention, shearing and stirring are preferably performed during granulation. The frequency of shearing and stirring is preferably 10-40 Hz, for example, 20 Hz. The duration of shearing and stirring is preferably 1-8 hours, for example, 300 minutes.

[0049] In this invention, cooling and sieving steps are preferably performed after granulation.

[0050] The cooling operation can be conventional in the art, and water cooling is preferred. The cooling endpoint is preferably below 50°C.

[0051] Preferably, a 200-mesh vibrating screen is used for the screening process.

[0052] In this invention, it is preferable that no depolymerization treatment is required during the preparation of the graphite anode material.

[0053] In this invention, such as Figure 1 As shown, the inventors discovered that a composite binder was prepared by incorporating an inorganic nano-anti-agglomeration agent 3 into asphalt 2, and then premixed and granulated with raw material coke 1 in sequence. This inorganic nano-anti-agglomeration agent 2 can achieve a dual mechanism of "steric hindrance" and "skeleton reinforcement"; it has extremely high specific surface area and activity, and can be uniformly dispersed and adsorbed on the surfaces of asphalt 2 and raw material coke 1 before granulation (e.g., ...). Figure 1(As shown in part a); During the high-temperature granulation process, asphalt transforms into asphalt molten phase 4 at high temperatures. The inorganic nano anti-agglomeration agent 3 acts like a "micro-bearing," creating physical gaps when the raw material coke particles approach each other, effectively preventing excessively tight particle adhesion due to excessively thick asphalt bridges. Furthermore, the inorganic nano anti-agglomeration agent 3, when combined with asphalt 2, forms a composite binder phase of "asphalt-inorganic nano anti-agglomeration agent." During granulation, this composite binder phase forms a micro-skeleton 5 composed of inorganic nano anti-agglomeration agent within its melt, reducing the free flow and migration of asphalt during heating, thereby preventing localized binder enrichment (e.g., ...). Figure 1 (As shown in parts b and c). This operation can reduce the generation of excessively bonded large particles at the source, significantly improve the sieving yield without the need for mechanical deagglomeration, and ensure the integrity of the obtained graphite anode material.

[0054] The present invention also provides a graphite anode material, which is prepared by the method for preparing graphite anode materials as described above.

[0055] In this invention, the D10 of the graphite anode material is preferably 4-13 μm, for example 10.8, 11.0, 10.6, 11.2 or 10.2 μm;

[0056] In this invention, the D50 of the graphite anode material is preferably 6-17 μm, for example 14.9, 14.7, 15.0, 14.6 or 15.1 μm;

[0057] In this invention, the D90 of the graphite anode material is preferably 15-22 μm, for example 20.3, 19.8, 20.8, 19.6 or 21.9 μm;

[0058] In this invention, the preferred particle size distribution of the graphite anode material is 0.5-0.8, for example, 0.64, 0.60, 0.68, 0.57 or 0.77.

[0059] In this invention, the tap density of the graphite anode material is preferably 0.90-1.15 g / cm³. 3 For example, 1.02, 1.03, or 1.04 g / cm³ 3 .

[0060] The present invention also provides an electrode comprising the graphite anode material as described above.

[0061] The present invention also provides a battery comprising the graphite negative electrode material as described above or the electrode as described above.

[0062] The positive and progressive effects of this invention are as follows:

[0063] The beneficial effects of this invention include:

[0064] (1) The method of preparing graphite anode material using the composite binder of the present invention is simple, low-cost, and does not require complex equipment modification. The added inorganic nano anti-agglomeration agent is low-cost and low-volume, making it very suitable for rapid application in existing industrial production. It can also reduce the formation of over-adhesive large particles >50μm from the source, thereby increasing the yield of qualified products after sieving by more than 89%.

[0065] (2) The graphite anode material prepared by the composite binder of the present invention has a narrower particle size distribution and a higher tap density, which is beneficial to improving the uniformity of coating during subsequent anode preparation.

[0066] Preferably, when the inorganic nano-anti-agglomeration agent is nano-alumina, it is believed to have a positive impact on the interfacial stability of the anode material. Attached Figure Description

[0067] Figure 1 This is a schematic diagram illustrating the mechanism of action of the composite binder of the present invention in the preparation of graphite anode materials.

[0068] Explanation of reference numerals in the attached figures:

[0069] 1-Raw material coke; 2-Asphalt; 3-Inorganic nano anti-agglomeration agent; 4-Melted asphalt phase; 5-Microskeleton formed by inorganic nano anti-agglomeration agent. Detailed Implementation

[0070] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0071] Figure 1 This is a schematic diagram illustrating the mechanism of action of the composite binder of the present invention in the preparation of graphite anode materials; Figure 1 Part a indicates that during the preparation of graphite anode materials, after the raw material coke and composite binder are mixed, pitch and inorganic nanoparticles are adsorbed on the surface of the raw material coke. Figure 1 Parts b and c indicate that during the granulation process, the inorganic nano anti-agglomeration agent forms a microskeleton in the asphalt molten phase through interfacial interaction at high temperature. The microskeleton plays a role in limiting the excessive adhesion of the raw material coke.

[0072] Example 1

[0073] Preparation of composite adhesive:

[0074] 392 kg of petroleum asphalt powder (particle size approximately 7 μm, softening point 207℃, coking value 62.8%) was mixed with 8 kg of nano-silica (particle size approximately 20 nm, specific surface area 93 m²). 2 The nano-silica was mixed in a mixer for 2 hours to obtain a uniform composite asphalt binder; the nano-silica in the composite binder was 2% by mass.

[0075] Granulation process:

[0076] 1. Take 4000 kg of needle coke (D50=7μm, true density 1.98g / cm³). 3 0.2% ash, 2% moisture, and 7% volatile matter were mixed with 400 kg of the above-mentioned composite binder in a mixer and stirred at room temperature (stirring speed of 15 Hz) for 90 minutes.

[0077] 2. Add the mixed materials to the granulation reactor, heat to 600℃ and keep at that temperature, while maintaining high-speed shear stirring at 20Hz for 300 minutes.

[0078] 3. After granulation, cool the material with cooling water until it is below 50°C before discharging.

[0079] 4. Use a 200-mesh vibrating screen for screening.

[0080] Example 2

[0081] The mass percentage of nano-silica in the composite binder was changed to 5%, and the rest was the same as in Example 1.

[0082] Example 3

[0083] The nano-silica in the composite binder was replaced with nano-alumina (particle size approximately 17 nm, specific surface area 98 m²). 2 / g), the rest is the same as in Example 1.

[0084] Example 4

[0085] The specific surface area of ​​nano-silica in the composite binder is 190 m². 2 / g, particle size approximately 10 nm, the remaining steps are exactly the same as in Example 1.

[0086] Example 5

[0087] The specific surface area of ​​nano-silica in the composite adhesive is 50 m². 2 / g, particle size approximately 40 nm, the remaining steps are exactly the same as in Example 1.

[0088] Comparative Example 1

[0089] The composite binder in the granulation process was replaced with 400 kg of petroleum asphalt binder (particle size of about 7 μm, softening point of 207°C, coking value of 62.8%), and the other steps and parameters were exactly the same as in Example 1.

[0090] Effect Example

[0091] 1. The D50 of the graphite anode materials prepared in Examples 1-5 and Comparative Example 1 were tested using a laser particle size analyzer.

[0092] 2. The tap density of the graphite anode materials prepared in Examples 1-5 and Comparative Example 1 was tested using a tap density meter.

[0093] 3. The method for testing the yield of qualified products is as follows: using a standard 200-mesh vibrating sieve, weigh the material on the sieve and the material under the sieve before and after sieving the graphite anode materials prepared in each example and comparative example.

[0094] The formula for calculating the yield of qualified products (%) is: yield of qualified products (%) = mass of undersize material (part that can pass through a 200-mesh sieve) / total mass of material before screening (kg) × 100%.

[0095] The test results are shown in Table 1.

[0096] Table 1

[0097]

[0098] As shown in Table 1, when an inorganic nano-anti-agglomeration agent is used in asphalt to prepare a composite binder, and then applied to the preparation of graphite anode materials, the resulting graphite anode materials have a relatively narrower particle size distribution (span), higher tap density, and higher yield of qualified products.

[0099] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A composite adhesive, characterized in that, The composite binder includes asphalt and an inorganic nano-anti-agglomeration agent; The inorganic nano-anti-agglomeration agent is one or more of oxides, carbides, nitrides, borides, silicides, and silicates.

2. The composite adhesive as described in claim 1, characterized in that, The composite adhesive satisfies one or more of the following conditions: (1) The type of asphalt is petroleum asphalt; (2) The particle size of the asphalt is 2μm-15μm, preferably 3μm-10μm, for example 7μm; (3) The softening point of the asphalt is 100℃-300℃, preferably 150℃-250℃, for example 200℃ or 207℃; (4) The coking value of the asphalt is 30%-90%, preferably 40%-80%, for example 62.8%; (5) The oxide is selected from metal oxides and / or non-metal oxides; The metal oxide preferably includes or is one or more of zinc oxide, magnesium oxide, zirconium oxide and aluminum oxide, such as aluminum oxide; The non-metallic oxide preferably includes or is silicon dioxide; (6) The carbide is selected from silicon carbide and / or boron carbide; (7) The nitride is selected from one or more of silicon nitride, aluminum nitride, titanium nitride, and boron nitride; (8) The boride is selected from one or more of titanium diboride, zirconium diboride and hafnium diboride.

3. The composite adhesive as described in claim 1, characterized in that, The composite adhesive satisfies one or more of the following conditions: (1) The particle size of the inorganic nano anti-agglomeration agent is 5-200 nm, preferably 10-100 nm, for example 10, 17, 20 or 40 nm; (2) The specific surface area of ​​the inorganic nano anti-agglomeration agent is 10 m². 2 / g-400m 2 / g, preferably 80-200m 2 / g, for example 50, 93, 98, 10 or 190m 2 / g; (3) The mass percentage of the asphalt is 90%-99.5%, preferably 95%-99.5%, for example 95% or 98%; The mass percentage indicates the percentage of asphalt in the composite binder by mass; (4) The inorganic nano anti-agglomeration agent has a mass percentage of 0.5%-10%, preferably 0.5%-5%, for example 2% or 5%; the mass percentage represents the mass percentage of the inorganic nano anti-agglomeration agent in the composite binder; Preferably, the inorganic nano-anti-agglomeration agent comprises or is silica and / or alumina.

4. A method for preparing a composite adhesive as described in any one of claims 1-3, characterized in that, It includes the following steps: mixing the asphalt and the inorganic nano anti-agglomeration agent.

5. The method for preparing the composite adhesive as described in claim 4, characterized in that, The preparation method of the composite adhesive satisfies (1) and / or (2) of the following conditions: (1) The mixing equipment is a mixer; (2) The mixing time is 1h-4h, for example 2h.

6. A method for preparing a graphite anode material, characterized in that, It includes the following steps: granulating a mixture comprising raw coke and the composite binder according to any one of claims 1-3 to obtain the graphite anode material.

7. The method for preparing the graphite anode material as described in claim 6, characterized in that, The preparation method of the graphite anode material satisfies one or more of the following conditions: (1) The type of raw coke is one or more of petroleum coke, pitch coke and needle coke, such as needle coke; (2) The true density of the raw coke is 1.5-2.5 g / cm³. 3 For example, 1.98 g / cm³ 3 ; (3) The ash content of the raw coke is <0.50%, for example 0.2%; (4) The moisture content of the raw coke is <4.0%, for example 2.0%; (5) The volatile matter content of the raw coke is 2.0%-10%, for example 7%; (6) The D50 of the raw coke is 3μm-15μm, for example 7μm or 9μm; (7) The mass ratio of the raw coke to the composite binder is (3-49):1, preferably (5-20):1, for example 10:1; (8) The granulation temperature is greater than the softening point of the asphalt, preferably 400-700℃, for example 600℃.

8. A graphite anode material, characterized in that, It is prepared using the method for preparing graphite anode material as described in claim 6 or 7; The D10 of the graphite anode material is preferably 4-13 μm, for example 10.8, 11.0, 10.6, 11.2 or 10.2 μm; The D50 of the graphite anode material is preferably 6-17 μm, for example 14.9, 14.7, 15.0, 14.6 or 15.1 μm; The D90 of the graphite anode material is preferably 15-22 μm, for example 20.3, 19.8, 20.8, 19.6 or 21.9 μm; The preferred particle size distribution of the graphite anode material is 0.5-0.8, for example, 0.64, 0.60, 0.68, 0.57 or 0.

77. The tap density of the graphite anode material is preferably 0.90-1.15 g / cm³. 3 For example, 1.02, 1.03, or 1.04 g / cm³. 3 .

9. An electrode, characterized in that, It includes the graphite anode material as described in claim 8.

10. A battery, characterized in that, It includes the graphite anode material as described in claim 8 or the electrode as described in claim 9.

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