Performance-tunable lithium-ion battery anode material co-production of silicon-carbon anode material and preparation method

Abstract

This invention relates to the co-production of performance-tunable lithium-ion battery anode materials and their preparation method, involving the distillation of coal tar followed by solid-liquid separation. The centrifuged heavy oil is extracted to obtain soluble and insoluble phases. The soluble phase is solvent-recovered and distilled to obtain purified heavy oil, which is then carbonized to obtain an artificial graphite precursor. This precursor is further processed through graphitization and granulation to obtain capacity-type and rate-type lithium-ion battery anode materials. The insoluble phase is dried, activated, oxidatively stabilized, and carbonized, then mixed with silicon powder, ground, and mixed with coated asphalt. After coating, a silicon-carbon anode precursor is obtained, which is then calcined to obtain a core-shell silicon-carbon anode material. This anode material is then blended with capacity-type and rate-type lithium-ion battery anode materials. The advantages are: this invention not only provides performance-tunable anode materials but also co-produces capacity-type and rate-type lithium-ion battery anode materials, core-shell silicon-carbon anode materials, and various feedstock oils. The preparation process is simple and the cost is low.

Description

Technical Field

[0001] This invention belongs to the field of silicon-carbon anode material technology, and particularly relates to a method for the co-production of silicon-carbon anode materials with adjustable performance of lithium-ion battery anode materials. Background Technology

[0002] With the development of society and technology, in order to meet the demand for multifunctional products, people have put forward increasingly higher requirements for the battery life, safety, and fast charging performance of lithium-ion batteries. Electrode materials are the core element that determines the performance of lithium-ion batteries and are also a major component affecting costs.

[0003] Lithium-ion battery anode materials are mainly divided into carbon-based materials and non-carbon-based materials. Carbon-based materials include natural graphite anodes, artificial graphite anodes, mesophase carbon microspheres (MCMB), soft carbon (such as coke) anodes, hard carbon anodes, carbon nanotubes, graphene, carbon fibers, etc. Non-carbon-based materials are mainly divided into silicon-based materials and their composites, nitride anodes, tin-based materials, lithium titanate, alloy materials, etc.

[0004] In lithium-ion batteries, the anode material acts as a carrier of lithium ions and electrons during charging, responsible for energy storage and release, accounting for approximately 8% of the manufacturing cost. Currently, commercially available anode materials are mainly graphite, but the theoretical specific capacity of graphite anodes in lithium-ion batteries is only 372 mAh / g. The actual specific capacity of commercially available high-end graphite materials is 360-365 mAh / g, which is very close to its theoretical specific capacity. Therefore, improving graphite anode materials has extremely limited impact on increasing the energy density of lithium-ion batteries. Silicon (Si) is considered one of the most promising anode materials for lithium-ion batteries. Elemental Si has a theoretical specific capacity as high as 3579 mAh / g at room temperature, making it a lithium-ion battery anode material with an extremely high theoretical specific capacity.

[0005] Currently, the main commercially available silicon-based anode materials include: carbon-coated silicon suboxide, nano-silicon carbide, silicon nanowires, and amorphous silicon alloys. Among these, carbon-coated silicon suboxide and nano-silicon carbide have the highest commercialization rates, both of which are used by doping graphite at a certain proportion (5%~10%). In recent years, silicon-based anodes have gradually moved towards industrial production, but the industrialization time is relatively short, and there are relatively few companies capable of mass production.

[0006] The raw materials for silicon-based anodes are mainly silicon and graphite. Silicon, as an anode material for lithium-ion batteries, has significant advantages. First, silicon alloys with lithium at room temperature, achieving a theoretical specific capacity of up to 4200 mAh / g, more than ten times that of current graphite-based anode materials. Second, compared to graphite, silicon is abundant and widely distributed in the Earth's crust, accounting for 25.8% of its mass, making it the second most abundant element in the crust. Third, silicon has a slightly higher potential plateau than graphite (approximately 0.4V, Li / Li+), eliminating the risk of lithium plating and ensuring better safety. Fourth, silicon-based anode materials exhibit superior low-temperature performance compared to graphite. Fifth, they provide channels for lithium-ion insertion and extraction from various directions, resulting in excellent fast-charging performance. Silicon anodes hold promise as an ideal replacement for graphite anodes. Summary of the Invention

[0007] To overcome the shortcomings of existing technologies, the purpose of this invention is to provide a method for the co-production of silicon-carbon anode materials with adjustable performance lithium-ion battery anode materials and a method for their preparation. This adjustable performance lithium-ion battery anode material has high initial efficiency, excellent cycle performance, and low volume expansion rate. During the preparation process, capacity-type anode materials, rate-type anode materials, core-shell silicon-carbon anode materials, and various high-quality feedstock oils are produced simultaneously, reducing the production cost of deep processing of coal tar.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A method for preparing silicon-carbon anode materials in conjunction with lithium-ion battery anode materials with tunable performance includes the following steps:

[0010] 1) The light oil in coal tar is removed by distillation to obtain heavy coal tar oil;

[0011] 2) Solid-liquid separation treatment of coal tar heavy oil is carried out to obtain heavy oil residue and heavy oil centrifuged liquid;

[0012] 3) The centrifuged liquid of heavy oil is mixed with the extractant, and after extraction and separation, soluble and insoluble phases are obtained respectively. The soluble phase is recovered by solvent and distilled to obtain purified heavy oil.

[0013] 4) Carbonize purified heavy oil to obtain artificial graphite precursor;

[0014] 5) Obtain capacity-type lithium-ion battery anode material by graphitizing artificial graphite precursor; obtain rate-type lithium-ion battery anode material by granulation of artificial graphite precursor;

[0015] 6) The insoluble phase obtained in step 3) is successively dried, activated, oxidatively stabilized and carbonized and then mixed with silicon powder. After grinding, it is mixed with coated asphalt and coated to obtain silicon-carbon anode precursor.

[0016] 7) The silicon-carbon anode precursor is calcined to obtain a core-shell silicon-carbon anode material;

[0017] 8) The core-shell silicon-carbon anode material is mixed with the capacity-type lithium-ion battery anode material and the rate-type lithium-ion battery anode material obtained in step 5) to obtain a lithium-ion battery anode material with adjustable specific capacity, first efficiency and rate.

[0018] In step 1), the coal tar is high-temperature coal tar with a quinoline insoluble content of 1% to 15%.

[0019] The reaction conditions for the distillation process are as follows: the bottom temperature of the column is controlled at 250~360℃, the top temperature of the column is controlled at 100~240℃, and the vacuum degree is controlled at 0.01~0.09MPa.

[0020] The light oil is the pre-distillate oil from high-temperature coal tar at 260~320℃;

[0021] The heavy coal tar oil contains 1% to 20% quinoline-insoluble matter and has a density of 1.13 to 1.3 g / cm³. 3 .

[0022] In step 2), the reaction conditions for the solid-liquid separation process are: separation temperature 60~150℃, separation time 0.5~10h, centrifugation speed 800~2000rad / min, and sieve mesh 100~900 mesh.

[0023] The content of quinoline-insoluble matter in the centrifuged heavy oil is 0~0.1%.

[0024] In step 3), the extractant is one or a mixture of two or more of acetone, benzene, toluene, xylene, pyridine, and quinoline;

[0025] The mass ratio of extractant to centrifuged heavy oil is (1~5):1;

[0026] The reaction conditions for the extraction and separation process are: extraction temperature 20~150℃, extraction time 0.5~10h, and sieve mesh size 300~1200 mesh.

[0027] The reaction conditions for solvent recovery are as follows: gas phase temperature 60–160°C, bottom temperature 100–280°C, vacuum degree 0.01–0.09 MPa, and residence time 0.5–2 h.

[0028] The distillation reaction conditions are as follows: gas phase temperature 160–280℃, bottom temperature 320–380℃, vacuum degree 0.01–0.06 MPa, and residence time 2–4 h.

[0029] The purified heavy oil contains 0-0.01% quinoline-insoluble matter, <0.05% ash, and has a density of 1.05-1.2 g / cm³. 3 The fraction before 300℃ is ≤10%.

[0030] In step 4), the carbonization reaction conditions are as follows: under nitrogen protection, the nitrogen flow rate is 300~1200ml / min, the heating rate is 1~10℃ / min, the final carbonization temperature is 700~2000℃, and the final temperature holding time is 1~20h.

[0031] The specifications of the artificial graphite precursor are: mesophase content ≥85%, ash content ≤0.01%.

[0032] In step 5), the reaction conditions for the graphitization treatment are: under argon protection, the heating rate is 1~20℃ / min, the final graphitization temperature is 2500~3000℃, and the final temperature is held for 1~10h.

[0033] The granulation process is as follows: adding coated bitumen to the artificial graphite precursor, with the coated bitumen addition ratio being 5wt%~15wt%, the reaction temperature being 600~900℃, and the reaction time being 2~10h.

[0034] The specifications of the capacity-type lithium-ion battery anode material are: D 10 6~15μm, D 50 15~24μm, D 90 ≤40.0μm, D max ≤50.0μm, specific surface area is 0.9~2.0m² 2 / g, tap density ≥0.92g / cm³ 3 Fixed carbon content ≥99.9%, graphitization degree ≥94.0%, initial discharge specific capacity ≥372.0mAh / g, initial coulombic efficiency ≥90%;

[0035] The index of the rate-type lithium-ion battery anode material is: D 10 6~15μm, D 50 15~24μm, D 90 ≤40.0μm, D max ≤50.0μm, specific surface area is 0.9~2.0m² 2 / g, tap density ≥0.92g / cm³ 3 Fixed carbon content ≥99.9%, graphitization degree ≥94.0%, initial discharge specific capacity ≥340.0mAh / g, and retention rate ≥80% after 600 cycles at 3C rate.

[0036] In step 6), the content of toluene-insoluble matter in the insoluble phase is 40%~90%, and the ash content is <0.05%;

[0037] The drying conditions are: drying temperature of 160~320℃, and drying time of 0.5~5h;

[0038] The activation reaction conditions are as follows: activation reaction temperature is 500~1000℃, reaction atmosphere is one of oxygen, air, and carbon dioxide, flow rate is 60~300L / h, and activation time is 0.5~15h;

[0039] The reaction conditions for the oxidation stabilization are: air temperature of 160~340℃, air flow rate of 1~10m³ / h. 3 / h, processing time 1~5h;

[0040] The carbonization reaction conditions are as follows: under nitrogen protection, the nitrogen flow rate is 300~1200ml / min, the heating rate is 1~10℃ / min, the final carbonization temperature is 700~2000℃, and the final temperature holding time is 1~20h.

[0041] The particle size D of the silicon powder 50 The wavelength range is 0.1~200nm; silicon powder accounts for 1%~20% of the mass of the insoluble phase after treatment;

[0042] The grinding process is as follows: stirring at a speed of 100~3000 rad / min for a stirring time of 1~20 h;

[0043] The softening point of the coated asphalt is 110~280℃, and the coking value is 20~80; the coated asphalt accounts for 5%~20% of the mass of the mixture of silica powder and the treated insoluble phase;

[0044] The reaction conditions for the coating treatment are as follows: under nitrogen protection at a rate of 0.1~0.5 L / min, the heating rate is 2~10℃ / min, the final temperature is 360~650℃, the time is 1~8h, and the converter frequency is 20~80Hz.

[0045] The specifications of the silicon-carbon anode precursor are as follows: specific surface area: 0.7~3m² 2 / g, tap density: 0.6~1.15g / cm³ 3 Ash content <0.05%.

[0046] In step 7), the reaction conditions for the calcination treatment are as follows: under nitrogen protection, the nitrogen flow rate is 300~1200 ml / min, the heating rate is 1~10℃ / min, the final calcination temperature is 700~1200℃, and the final temperature holding time is 1~30 h.

[0047] The core-shell silicon-carbon anode material has the following specifications: particle size distribution D. 10 6~12μm, D 50 15~24μm, D90 : 28~45μm, true density ≥2.24g / cm³ 3 Tap density ≥ 0.9 g / cm³ 3 The compacted density of the powder is ≥1.55 g / cm³. 3 Ash content ≤0.01%, initial coulombic efficiency ≥80%, initial discharge specific capacity ≥450mAh / g, capacity retention rate ≥80% after 100 0.1C cycles, cycle performance ≥400 cycles, rate performance ≥80% at 2C / 0.2C.

[0048] In step 8), the core-shell type silicon-carbon anode material, the capacity type lithium battery anode material, and the rate type lithium battery anode material are mixed in a mass ratio of 10:(1~20):(1~10).

[0049] A performance-tunable lithium-ion battery anode material co-produced with silicon-carbon anode material, wherein the performance-tunable lithium-ion battery anode material has the following specifications: ash content ≤0.01%, initial discharge specific capacity ≥400mAh / g, initial coulombic efficiency ≥85%, capacity retention rate ≥80% after 100 0.2C cycles, cycle performance ≥400 cycles, and rate performance ≥80% at 2C / 0.2C.

[0050] Compared with the prior art, the beneficial effects of the present invention are:

[0051] 1. The performance-tunable lithium-ion battery anode material of this invention exhibits high initial efficiency, excellent cycle performance, and low volume expansion. Its specifications are: ash content ≤ 0.01%, specific surface area ≤ 1.8 m². 2 / g, initial discharge specific capacity ≥400mAh / g, initial coulombic efficiency ≥85%, capacity retention ≥80% after 100 0.2C cycles, cycle performance ≥400 cycles, rate performance (2C / 0.2C) ≥80%.

[0052] 2. This invention not only provides high-performance, tunable anode materials for the lithium battery field, but also co-produces capacity-type lithium-ion battery anode materials, rate-type lithium-ion battery anode materials, core-shell silicon-carbon anode materials, and various high-quality feedstocks. Among these, the capacity-type lithium-ion battery anode material can serve as a primary raw material for high-capacity lithium-ion battery anode materials, and its specifications include D... 10 6~15μm, D 50 15~24μm, D 90 ≤40.0μm, D max ≤50.0μm, specific surface area: 0.9~2.0m² 2 / g, tap density ≥0.92g / cm³ 3The fixed carbon content is ≥99.9%, graphitization degree is ≥94.0%, initial discharge specific capacity is ≥372.0 mAh / g, and initial coulombic efficiency is ≥90%. This rate-capable lithium-ion battery anode material can be used as a main raw material for high-rate lithium-ion battery anode materials. Its specifications are: D... 10 6~15μm, D 50 15~24μm, D 90 ≤40.0μm, D max ≤50.0μm, specific surface area: 0.9~2.0m² 2 / g, tap density ≥0.92g / cm³ 3 The core-shell silicon-carbon anode material has a fixed carbon content ≥99.9%, a graphitization degree ≥94.0%, an initial discharge specific capacity ≥340.0 mAh / g, and a cycle retention rate ≥80% after 600 cycles at 3C rate. It can serve as a primary raw material for silicon-carbon anode materials with low volume expansion and high / ultra-capacity. Its specifications include a particle size distribution of D... 10 : 6~12μm, D 50 15~24μm, D 90 : 28~45μm, true density ≥2.24g / cm³ 3 Tap density ≥ 0.9 g / cm³ 3 The compacted density of the powder is ≥1.55 g / cm³. 3 Ash content ≤0.01%, specific surface area ≤1.8m² 2 The purified heavy oil exhibits the following characteristics: initial coulombic efficiency ≥80%, initial discharge specific capacity ≥450mAh / g, capacity retention ≥80% after 100 0.1C cycles, cycle performance ≥400 cycles, and rate performance (2C / 0.2C) ≥80%. It can be used as a raw material for producing coal-based spinnable pitch, mesophase pitch, and needle coke; the heavy oil residue can be used as an asphalt additive for modified pitch and binders. The specifications for purified heavy oil are: quinoline insoluble content 0~0.01%, ash content <0.05%, and density (20℃) 0.95~1.3g / cm³. 3 The fraction before 300℃ is ≤10%.

[0053] 3. This invention not only provides high-performance, adjustable anode materials for the lithium battery field, but also co-produces capacity-type anode materials, rate-type anode materials, core-shell silicon-carbon anode materials, and various high-quality raw material oils. The preparation process is simple, the manufacturing cost is low, and it is safe, reliable, and pollution-free. It reduces the production cost of deep processing of coal tar, improves the overall competitiveness of lithium battery anode materials and silicon-carbon anode materials, and solves the problem of efficient and high-value-added utilization of coal tar. Attached Figure Description

[0054] Figure 1 This is a charge-discharge curve of a lithium-ion battery anode material with adjustable performance.

[0055] Figure 2 This is a cycle curve of a lithium-ion battery anode material with adjustable performance.

[0056] Figure 3 This is a scanning electron microscope (SEM) image of a core-shell silicon-carbon anode material.

[0057] Figure 4 This is a polarized light microstructure diagram of a core-shell silicon-carbon anode material. Detailed Implementation

[0058] The present invention will now be described in detail, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0059] A method for preparing silicon-carbon anode materials in conjunction with lithium-ion battery anode materials with tunable performance includes the following steps:

[0060] 1) The light oil in coal tar is removed by distillation to obtain heavy coal tar oil.

[0061] The coal tar is high-temperature coal tar with a quinoline-insoluble content of 1%–15%. The distillation reaction conditions are: bottom temperature controlled at 250–360℃, top temperature controlled at 100–240℃, and vacuum degree controlled at 0.01–0.09 MPa. The light oil is the 260–320℃ pre-distillate from the high-temperature coal tar. The resulting heavy coal tar oil has a quinoline-insoluble content of 1%–20% and a density (20℃) of 1.13–1.3 g / cm³. 3 .

[0062] 2) Solid-liquid separation treatment of coal tar heavy oil is carried out to obtain heavy oil residue and heavy oil centrifuged liquid;

[0063] The reaction conditions for solid-liquid separation are as follows: separation temperature 60~150℃, separation time 0.5~10h, centrifugation speed 800~2000rad / min, and sieve mesh size 100~900 mesh; the content of quinoline insoluble matter in the obtained heavy oil centrifuged liquid is 0~0.1%. The obtained heavy oil residue can be used as an asphalt additive for modified asphalt and binders.

[0064] 3) The centrifuged liquid of heavy oil is mixed with an extractant, and after extraction and separation, soluble and insoluble phases are obtained separately. The soluble phase is then subjected to solvent recovery and distillation to obtain purified heavy oil. The purified heavy oil can be used as a raw material for the production of coal-based spinnable pitch, mesophase pitch, or needle coke.

[0065] The reaction conditions for extraction and separation are as follows: extraction temperature 20~150℃, extraction time 0.5~10h, sieve mesh 300~1200 mesh; the extractant is one or a mixture of two or more of acetone, benzene, toluene, xylene, pyridine, and quinoline; the mass ratio of extractant to heavy oil centrifuged liquid is (1~5):1.

[0066] The reaction conditions for solvent recovery are: gas phase temperature 60–160℃, bottom temperature 100–280℃, vacuum degree 0.01–0.09MPa, and residence time 0.5–2h.

[0067] The distillation reaction conditions are: gas phase temperature 160-280℃, bottom temperature 320-380℃, vacuum degree 0.01-0.06MPa, and residence time 2-4h.

[0068] The purified heavy oil obtained contained 0-0.01% quinoline-insoluble matter, <0.05% ash, and had a density (20℃) of 1.05-1.2 g / cm³. 3 The fraction before 300℃ is ≤10%. Purified heavy oil can be used as a raw material for the production of coal-based spinnable pitch, mesophase pitch and needle coke.

[0069] 4) The purified heavy oil was carbonized to obtain the artificial graphite precursor. The carbonization reaction conditions were as follows: under nitrogen protection, the nitrogen flow rate was 300~1200 ml / min, the heating rate was 1~10℃ / min, the final carbonization temperature was 700~2000℃, and the final temperature holding time was 1~20 h. The indicators of the obtained artificial graphite precursor were: mesophase content ≥85%, ash content ≤0.01%.

[0070] 5) Obtain capacity-type lithium-ion battery anode material by graphitizing artificial graphite precursor; obtain rate-type lithium-ion battery anode material by granulation of artificial graphite precursor.

[0071] The reaction conditions for graphitization are as follows: under argon protection, the heating rate is 1~20℃ / min, the final graphitization temperature is 2500~3000℃, and the final temperature is held for 1~10h; the granulation treatment is as follows: coating asphalt is added to the artificial graphite precursor, the coating asphalt addition ratio is 5wt%~15wt%, the reaction temperature is 600~900℃, and the reaction time is 2~10h.

[0072] The obtained capacity-type lithium battery anode material has the following specifications: D 10 6~15μm, D 50 15~24μm, D 90 ≤40.0μm, D max ≤50.0μm, specific surface area is 0.9~2.0m² 2 / g, tap density ≥0.92g / cm³ 3Fixed carbon content ≥99.9%, graphitization degree ≥94.0%, initial discharge specific capacity ≥372.0mAh / g, initial coulombic efficiency ≥90%.

[0073] The obtained high-rate lithium-ion battery anode material has the following specifications: D 10 6~15μm, D 50 15~24μm, D 90 ≤40.0μm, D max ≤50.0μm, specific surface area is 0.9~2.0m² 2 / g, tap density ≥0.92g / cm³ 3 Fixed carbon content ≥99.9%, graphitization degree ≥94.0%, initial discharge specific capacity ≥340.0mAh / g, and retention rate ≥80% after 600 cycles at 3C rate.

[0074] 6) The insoluble phase obtained in step 3) is dried, activated, oxidized and stabilized, and carbonized in sequence and then mixed with silicon powder. After grinding, it is mixed with coated asphalt and coated to obtain silicon-carbon anode precursor.

[0075] The insoluble phase contains 40%–90% toluene-insoluble matter and <0.05% ash. Drying conditions are: drying temperature 160–320℃, drying time 0.5–5 h. Activation conditions are: activation temperature 500–1000℃, reaction atmosphere of oxygen, air, or carbon dioxide, flow rate 60–300 L / h, activation time 0.5–15 h. Oxidative stabilization conditions are: air temperature 160–340℃, air flow rate 1–10 m³ / h. 3 The processing time is 1-5 hours. The carbonization reaction conditions are: under nitrogen protection, nitrogen flow rate is 300-1200 ml / min, heating rate is 1-10℃ / min, final carbonization temperature is 700-2000℃, and the holding time at the final temperature is 1-20 hours. The particle size D of the silica powder... 50 The surface area is 0.1~200 nm; silicon powder accounts for 1%~20% of the mass of the treated insoluble phase. The grinding process involves stirring at a speed of 100~3000 rad / min for 1~20 h. The softening point of the coated asphalt is 110~280℃, and the coking value is 20~80; the coated asphalt accounts for 5%~20% of the mass of the mixture of silicon powder and the treated insoluble phase. The reaction conditions for the coating process are: under nitrogen protection at a rate of 0.1~0.5 L / min, a heating rate of 2~10℃ / min, a final temperature of 360~650℃, a time of 1~8 h, and a converter frequency of 20~80 Hz. The obtained silicon-carbon anode precursor has the following properties: specific surface area: 0.7~3 m² / min. 2 / g, tap density: 0.6~1.15g / cm³ 3Ash content <0.05%.

[0076] 7) The silicon-carbon anode precursor was calcined to obtain a core-shell silicon-carbon anode material. The calcination conditions were as follows: under nitrogen protection, nitrogen flow rate was 300–1200 ml / min, heating rate was 1–10 °C / min, final calcination temperature was 700–1200 °C, and the holding time at the final temperature was 1–30 h. (See...) Figure 3 , Figure 4 The obtained core-shell silicon-carbon anode material has the following properties: particle size distribution is D 10 : 6~12μm, D 50 15~24μm, D 90 : 28~45μm, true density ≥2.24g / cm³ 3 Tap density ≥ 0.9 g / cm³ 3 The compacted density of the powder is ≥1.55 g / cm³. 3 Ash content ≤0.01%, initial coulombic efficiency ≥80%, initial discharge specific capacity ≥450mAh / g, capacity retention ≥80% after 100 0.1C cycles, cycle performance ≥400 cycles, rate performance (2C / 0.2C) ≥80%.

[0077] 8) The core-shell silicon-carbon anode material and the capacity-type lithium-ion battery anode material and the rate-type lithium-ion battery anode material obtained in step 5) are mixed in a mass ratio of 10:(1~20):(1~10) to obtain a lithium-ion battery anode material with adjustable specific capacity, first efficiency and rate.

[0078] The performance indicators of the adjustable lithium-ion battery anode material are as follows: ash content ≤0.01%, initial discharge specific capacity ≥400mAh / g, initial coulombic efficiency ≥85%, capacity retention ≥80% after 100 0.2C cycles, cycle performance ≥400 cycles, rate performance (2C / 0.2C) ≥80%. (See details...) Figure 1 , Figure 2 .

[0079] Example 1:

[0080] Examples 1-5 show the co-production of silicon-carbon anode materials with adjustable performance of lithium-ion battery anode materials, preparation process parameters, and test results, as shown in Tables 1-5.

[0081] Table 1. Preparation process and indicators of artificial graphite precursor

[0082]

[0083] Table 2 Preparation process and indicators of capacity-type lithium battery anode materials

[0084]

[0085] Table 3. Preparation process and indicators of rate-capable lithium-ion battery anode materials

[0086]

[0087] Table 4. Preparation process and indicators of core-shell silicon-carbon anode materials

[0088]

[0089]

[0090] Table 5 Performance Indicators of Adjustable Lithium-ion Battery Anode Materials

[0091]

[0092] This invention not only provides lithium battery industry with high initial efficiency, excellent cycle performance, and low volume expansion rate of adjustable anode materials, but also co-produces capacity-type anode materials, rate-type anode materials, core-shell silicon-carbon anode materials, and various high-quality raw material oils. The preparation process is simple, the manufacturing cost is low, and it is safe, reliable, and pollution-free. It reduces the production cost of deep processing of coal tar, improves the overall competitiveness of lithium battery anode material products and silicon-carbon anode material products, and solves the problem of efficient and high-value-added utilization of coal tar.

Claims

1. A method for preparing silicon-carbon anode materials in conjunction with lithium-ion battery anode materials with tunable performance, characterized in that, Includes the following steps: 1) The light oil in coal tar is removed by distillation to obtain heavy coal tar oil; 2) Solid-liquid separation treatment of coal tar heavy oil is carried out to obtain heavy oil residue and heavy oil centrifuged liquid; 3) The centrifuged liquid of heavy oil is mixed with the extractant, and after extraction and separation, soluble and insoluble phases are obtained respectively. The soluble phase is recovered by solvent and distilled to obtain purified heavy oil. 4) Carbonize purified heavy oil to obtain artificial graphite precursor; 5) Obtain capacity-type lithium-ion battery anode material by graphitizing artificial graphite precursor; obtain rate-type lithium-ion battery anode material by granulation of artificial graphite precursor; 6) The insoluble phase obtained in step 3) is successively dried, activated, oxidatively stabilized and carbonized and then mixed with silicon powder. After grinding, it is mixed with coated asphalt and coated to obtain silicon-carbon anode precursor. 7) The silicon-carbon anode precursor is calcined to obtain a core-shell silicon-carbon anode material; 8) The core-shell silicon-carbon anode material is mixed with the capacity-type lithium-ion battery anode material and the rate-type lithium-ion battery anode material obtained in step 5) to obtain a lithium-ion battery anode material with adjustable specific capacity, first efficiency and rate.

2. The preparation method for the co-production of silicon-carbon anode material with tunable lithium-ion battery anode material according to claim 1, characterized in that, In step 1), the coal tar is high-temperature coal tar with a quinoline insoluble content of 1% to 15%. The reaction conditions for the distillation process are as follows: the bottom temperature of the column is controlled at 250~360℃, the top temperature of the column is controlled at 100~240℃, and the vacuum degree is controlled at 0.01~0.09MPa. The light oil is the pre-distillate oil from high-temperature coal tar at 260~320℃; The heavy coal tar oil contains 1% to 20% quinoline-insoluble matter and has a density of 1.13 to 1.3 g / cm³. 3 .

3. The preparation method of silicon-carbon anode material in conjunction with the production of lithium-ion battery anode material with adjustable performance according to claim 1, characterized in that, In step 2), the reaction conditions for the solid-liquid separation process are: separation temperature 60~150℃, separation time 0.5~10h, centrifugation speed 800~2000rad / min, and sieve mesh 100~900 mesh. The content of quinoline-insoluble matter in the centrifuged heavy oil is 0~0.1%.

4. The preparation method of silicon-carbon anode material in conjunction with the production of lithium-ion battery anode material with adjustable performance according to claim 1, characterized in that, In step 3), the extractant is one or a mixture of two or more of acetone, benzene, toluene, xylene, pyridine, and quinoline; The mass ratio of extractant to centrifuged heavy oil is (1~5):1; The reaction conditions for the extraction and separation process are: extraction temperature 20~150℃, extraction time 0.5~10h, and sieve mesh size 300~1200 mesh. The reaction conditions for solvent recovery are: gas phase temperature 60–160°C, bottom temperature 100–280°C, vacuum degree 0.01–0.09 MPa, and residence time 0.5–2 h. The distillation reaction conditions are as follows: gas phase temperature 160-280℃, bottom temperature 320-380℃, vacuum degree 0.01-0.06MPa, and residence time 2-4h. The purified heavy oil contains 0-0.01% quinoline-insoluble matter, <0.05% ash, and has a density of 1.05-1.2 g / cm³. 3 The fraction before 300℃ is ≤10%.

5. The preparation method of silicon-carbon anode material in conjunction with the production of lithium-ion battery anode material with adjustable performance according to claim 1, characterized in that, In step 4), the carbonization reaction conditions are as follows: under nitrogen protection, the nitrogen flow rate is 300~1200ml / min, the heating rate is 1~10℃ / min, the final carbonization temperature is 700~2000℃, and the final temperature holding time is 1~20h. The specifications of the artificial graphite precursor are: mesophase content ≥85%, ash content ≤0.01%.

6. The preparation method of silicon-carbon anode material in conjunction with the production of lithium-ion battery anode material with adjustable performance according to claim 1, characterized in that, In step 5), the reaction conditions for the graphitization treatment are: under argon protection, the heating rate is 1~20℃ / min, the final graphitization temperature is 2500~3000℃, and the final temperature is held for 1~10h. The granulation process is as follows: adding coated bitumen to the artificial graphite precursor, with the coated bitumen addition ratio being 5wt%~15wt%, the reaction temperature being 600~900℃, and the reaction time being 2~10h. The specifications of the capacity-type lithium-ion battery anode material are: D 10 6~15μm, D 50 15~24μm, D 90 ≤40.0μm, D max ≤50.0μm, specific surface area is 0.9~2.0m² 2 / g, tap density ≥0.92g / cm³ 3 Fixed carbon content ≥99.9%, graphitization degree ≥94.0%, initial discharge specific capacity ≥372.0mAh / g, initial coulombic efficiency ≥90%; The index of the rate-type lithium-ion battery anode material is: D 10 6~15μm, D 50 15~24μm, D 90 ≤40.0μm, D max ≤50.0μm, specific surface area is 0.9~2.0m² 2 / g, tap density ≥0.92g / cm³ 3 Fixed carbon content ≥99.9%, graphitization degree ≥94.0%, initial discharge specific capacity ≥340.0mAh / g, and retention rate ≥80% after 600 cycles at 3C rate.

7. The preparation method of a silicon-carbon anode material co-produced with a performance-tunable lithium-ion battery anode material according to claim 1, characterized in that, In step 6), the content of toluene-insoluble matter in the insoluble phase is 40%~90%, and the ash content is <0.05%; The drying conditions are: drying temperature of 160~320℃, and drying time of 0.5~5h; The activation reaction conditions are as follows: activation reaction temperature is 500~1000℃, reaction atmosphere is one of oxygen, air, and carbon dioxide, flow rate is 60~300L / h, and activation time is 0.5~15h; The reaction conditions for the oxidation stabilization are: air temperature of 160~340℃, air flow rate of 1~10m³ / h. 3 / h, processing time 1~5h; The carbonization reaction conditions are as follows: under nitrogen protection, the nitrogen flow rate is 300~1200ml / min, the heating rate is 1~10℃ / min, the final carbonization temperature is 700~2000℃, and the final temperature holding time is 1~20h. The particle size D of the silicon powder 50 The wavelength range is 0.1~200nm; silicon powder accounts for 1%~20% of the mass of the insoluble phase after treatment; The grinding process is as follows: stirring at a speed of 100~3000 rad / min for a stirring time of 1~20 h; The softening point of the coated asphalt is 110~280℃, and the coking value is 20~80; the coated asphalt accounts for 5%~20% of the mass of the mixture of silica powder and the treated insoluble phase; The reaction conditions for the coating treatment are as follows: under nitrogen protection at a rate of 0.1~0.5 L / min, the heating rate is 2~10℃ / min, the final temperature is 360~650℃, the time is 1~8h, and the converter frequency is 20~80Hz. The specifications of the silicon-carbon anode precursor are as follows: specific surface area: 0.7~3m² 2 / g, tap density: 0.6~1.15g / cm³ 3 Ash content <0.05%.

8. The preparation method of silicon-carbon anode material in conjunction with the production of lithium-ion battery anode material with adjustable performance according to claim 1, characterized in that, In step 7), the reaction conditions for the calcination treatment are as follows: under nitrogen protection, the nitrogen flow rate is 300~1200 ml / min, the heating rate is 1~10℃ / min, the final calcination temperature is 700~1200℃, and the final temperature holding time is 1~30 h. The core-shell silicon-carbon anode material has the following specifications: particle size distribution D. 10 : 6~12μm, D 50 15~24μm, D 90 : 28~45μm, true density ≥2.24g / cm³ 3 Tap density ≥ 0.9 g / cm³ 3 The compacted density of the powder is ≥1.55 g / cm³. 3 Ash content ≤0.01%, initial coulombic efficiency ≥80%, initial discharge specific capacity ≥450mAh / g, capacity retention rate ≥80% after 100 0.1C cycles, cycle performance ≥400 cycles, rate performance ≥80% at 2C / 0.2C.

9. The method for preparing silicon-carbon anode material in conjunction with the production of lithium-ion battery anode material with adjustable performance according to claim 1, characterized in that, In step 8), the core-shell type silicon-carbon anode material, the capacity type lithium battery anode material, and the rate type lithium battery anode material are mixed in a mass ratio of 10:(1~20):(1~10).

10. A method for preparing a lithium-ion battery anode material with tunable performance as described in claim 1, and co-producing a silicon-carbon anode material, characterized in that, The performance indicators of the adjustable lithium battery anode material are as follows: ash content ≤0.01%, initial discharge specific capacity ≥400mAh / g, initial coulombic efficiency ≥85%, capacity retention rate after 100 0.2C cycles ≥80%, cycle performance ≥400 cycles, and rate performance 2C / 0.2C ≥80%.

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