Negative electrode reinforcing composition, and preparation method and use

Abstract

A negative electrode reinforcing composition, and a preparation method and the use. The negative electrode reinforcing composition comprises a component A and a component B. The preparation raw materials of the component A comprise an asphalt powder, a polyvinyl alcohol powder, a redispersible glue powder and a phenolic resin powder in a mass ratio of 10-90:10-90:0-10:0-40. The component B comprises an aqueous solution containing calcium chloride and hydrochloric acid. The mass ratio of the component A to the component B is 1-8:7-28. The negative electrode reinforcing composition can make a carbon micropowder present a good strength curve during the process of preparing artificial graphite, so as to avoid powdering and powder loss caused by slightly low strength, and rough surface, tap density reduction and low product quality of a terminal product caused by subsequent crushing and grinding required by excessively high strength. In addition, the negative electrode reinforcing composition can effectively reduce the impurity level of high-melting-point and high-boiling-point metal elements and compounds in obtained carbon particles, reduce the co-melting point by means of a blend, and avoid the enrichment, coking and hardening of high-melting-point impurities in a graphitization furnace.

Description

Negative electrode enhancement composition, preparation method and application Technical Field

[0001] This application relates to the field of carbon materials technology, and more particularly to auxiliary materials for the preparation of carbon materials, and even more particularly to negative electrode reinforcement compositions, preparation methods and applications. Background Technology

[0002] Current processes for producing artificial graphite anode materials involve sequentially crushing, grinding, grading, coating and granulating, carbonizing, briquetting, and graphitizing the raw materials. The equipment used in each process is intermittent or batch-type, especially the graphitization process, where the batch-type graphitization equipment results in high energy consumption and cost. To overcome the drawbacks of existing batch graphitization processes such as Atchison furnaces, internal furnaces, or box furnaces, which suffer from long cycles and high energy consumption, vertical continuous graphitization processes and equipment have become a popular research direction.

[0003] However, the vertical continuous graphitization process requires the feed material to be granular, not powdery. Otherwise, high-volatile impurities in the furnace will vaporize and overflow, washing away the carbon micropowder. If the gas overflow channel is blocked, a furnace blowout accident may also occur. Therefore, in recent years, there has been an increasing investment in the research and development of vertical continuous graphitization processes, methods, and furnace equipment. Efforts are being made to explore the use of binder granulation to solve the problem of powder being washed away and lost by high-temperature gases in the vertical graphitization furnace.

[0004] For example, starch and PVA solution can be used as binders to granulate carbon micropowder, or cassava flour can be used as a binder and water as a solvent. However, these methods have drawbacks. While they may show good bonding strength for wet or dry granules, during the drying, carbonization, and graphitization process, PVA and cassava flour undergo a transformation process as the temperature gradually increases, progressing from vitrification and embrittlement to etherification, carbonization, and incomplete graphitization. During the vitrification, embrittlement, etherification, and initial carbonization stages, their bonding performance is low, and the bonded carbon particles are easily broken and pulverized. Carbonization and graphitization in a vertical graphitization furnace can result in powder loss. Although increasing the amount of PVA or starch can reduce the breakage and powder loss of carbon particles, it can lead to excessively high particle strength after graphitization, requiring further grinding. Grinding, in turn, results in a rough product surface, reduced compaction density, and poor product quality. Therefore, existing binders cannot solve the safety hazards of coking plates forming and pressing in vertical continuous graphitization furnaces.

[0005] Furthermore, the existing vertical continuous graphitization process also has another safety hazard: the carbon micropowder contains high-melting-point and high-volatility-point impurities such as Fe2O3 (melting point 1565℃), Fe (melting point 1538℃), CaO (melting point 2572℃), SiO2 (melting point 1723℃), and CaSiO4 (melting point 1540℃). These high-melting-point impurities accumulate and caking in the upper 900℃ to 1300℃ region of the vertical continuous graphitization furnace, blocking the high-temperature gas overflow channels and easily causing furnace pressure burst accidents. At the same time, a large amount of gas will overflow from the high-temperature graphitization zone, resulting in the loss of carbon micropowder due to being washed away.

[0006] Therefore, it is necessary to provide a composition suitable for carbon micropowder bonding and granulation to overcome the above-mentioned defects and safety hazards of the prior art and achieve the industrialization of the vertical continuous graphitization process.

[0007] Application content

[0008] In view of the above problems, the purpose of this application is to provide a negative electrode reinforcing composition, a preparation method, and an application. This negative electrode reinforcing composition enables carbon micropowder to exhibit a good strength curve during the preparation of artificial graphite, thereby avoiding the loss of powder due to low strength and powder runoff, and the need for subsequent crushing and grinding due to excessive strength, resulting in a rough surface, reduced tap density, and low product quality in the final product. In addition, this negative electrode reinforcing composition can reduce the content of high-melting-point and high-volatility-point metallic elements and compound impurities in the prepared carbon particles, avoiding the enrichment, coking, and caking of high-melting-point and high-volatility-point metallic elements and compound impurities in the graphitization furnace.

[0009] To achieve the above objectives, the first aspect of this application provides a negative electrode enhancement composition comprising component A and component B. The raw materials for preparing component A include asphalt powder, polyvinyl alcohol powder, redispersible polymer powder, and phenolic resin powder in a mass ratio of 10–90:10–90:0–10:0–40. Component B comprises an aqueous solution containing calcium chloride and hydrochloric acid. The mass ratio of component A to component B is 1–8:7–28.

[0010] The technical solution adopted in this application has at least the following technical effects.

[0011] (1) Component A includes asphalt powder, polyvinyl alcohol powder, redispersible polymer powder, and phenolic resin powder, which is a dry powder binder component. Component B includes an aqueous solution containing calcium chloride and hydrochloric acid, which is a liquid component. By compounding the dry powder binder component and the liquid component, the dry powder binder component can be evenly dispersed on the surface of the carbon micropowder under the action of the liquid component. After subsequent drying, the dry powder binder component can improve the burst strength after being hot-melted. Therefore, it can bind and granulate the carbon micropowder to improve its strength, thereby avoiding loss caused by being washed away by high-temperature gas.

[0012] (2) The raw materials for preparing component A include asphalt powder, polyvinyl alcohol powder, redispersible polymer powder, and phenolic resin powder in a mass ratio of 10-90:10-90:0-10:0-40, meaning that component A contains at least asphalt powder and polyvinyl alcohol powder. Polyvinyl alcohol powder provides suitable free-fall fracture resistance for carbon particles, while asphalt powder, through thermosetting during the drying stage, improves the strength of carbon particles, compensating for the defects caused by the glass transition and embrittlement of polyvinyl alcohol between 100℃ and 300℃, which lowers the strength of carbon particles. Therefore, the synergistic effect of polyvinyl alcohol powder and asphalt powder ensures that carbon particles have high free-fall fracture resistance in both the initial stage and the drying stage before carbonization, exhibiting a good strength curve during the preparation of artificial graphite. This avoids the loss of powder due to low strength and the need for subsequent grinding and crushing, resulting in a rough surface, reduced tap density, and low product quality in the final product.

[0013] (3) Based on the condition that the mass ratio of redispersible polymer powder and phenolic resin powder in component A is greater than 0, that is, when redispersible polymer powder and phenolic resin powder are present, the redispersible polymer powder has water-reducing and binding properties, which can reduce the moisture content of component B. Therefore, it can further ensure the strength of carbon particles and improve drying efficiency and reduce drying energy consumption. Phenolic resin powder can also improve the strength of carbon particles through thermosetting during the drying stage, further compensating for the defects of low strength of carbon particles caused by glassization and embrittlement of polyvinyl alcohol between 100℃ and 300℃. At the same time, the composite of phenolic resin powder and asphalt powder can be used to adjust the degree of graphitization, so as to obtain artificial graphite with precise graphitization.

[0014] (4) Component B includes an aqueous solution containing calcium chloride and hydrochloric acid. The hydrochloric acid can react with high-melting-point and high-volatility-point metallic elements and metallic compound impurities in the carbon micropowder, transforming them into low-melting-point and low-boiling-point metallic elements and metallic compounds (such as converting Fe2O3 with a melting point of 1565℃ and a boiling point of 3414℃ and metallic Fe with a boiling point of 2750℃ into FeCl3 with a melting point of 306℃ and a boiling point of 319℃, and CaO into CaCl2, etc.). This allows for low-temperature impurity removal after subsequent low-temperature drying, preventing the high-melting-point and high-volatility-point metallic elements and metallic compound impurities from accumulating and forming coke in the graphitization furnace. In addition, it can also reduce the amount of high-temperature gas generated by high-melting-point and high-volatility-point metallic elements and metallic compounds during high-temperature graphitization and the probability of these impurities consuming the carbon source in the carbon micropowder. Calcium chloride in component B can melt at its melting point during the subsequent preparation of artificial graphite, thereby increasing its strength and compensating for the insufficient bonding strength of component A during the initial carbonization process. Furthermore, calcium chloride can form blends with high-melting-point impurities such as SiO2 and CaSiO4 in carbon micropowder, reducing their melting point and eliminating the risk of coke caking and pressure buildup in the vertical graphitization furnace caused by these impurities. Calcium chloride also enhances and prevents the breakage of carbon particles within the temperature range of room temperature to 772°C.

[0015] As one technical solution of this application, the polyvinyl alcohol powder includes at least two polyvinyl alcohols with different degrees of polymerization.

[0016] As one technical solution of this application, the polyvinyl alcohol powder includes PVA1788 and PVA2488.

[0017] As one technical solution of this application, the particle size of the asphalt powder is from 0.01μm to 80.00μm.

[0018] As one technical solution of this application, the particle size of the polyvinyl alcohol powder is from 0.01 μm to 100.00 μm.

[0019] As one technical solution of this application, the particle size of the redispersible adhesive powder is from 0.01 μm to 80.00 μm.

[0020] As one technical solution of this application, the particle size of the phenolic resin powder is from 0.01 μm to 80.00 μm.

[0021] As a technical solution of this application, the raw materials for preparing component B include calcium chloride aqueous solution, hydrochloric acid and water in a mass ratio of 20-60:1-20:40-80.

[0022] As one technical solution of this application, the mass concentration of the calcium chloride aqueous solution is 2% to 50%, and the molar concentration of the hydrochloric acid is 0.01 mol / L to 5.00 mol / L.

[0023] A second aspect of this application provides a method for preparing a negative electrode enhancement composition, comprising:

[0024] (1) Weigh each substance in component A according to the formula amount, mix them evenly in the first mixer, and store them for later use;

[0025] (2) Weigh each substance in component B according to the formula and mix them evenly in the second mixer before storing and keeping them for later use.

[0026] Mix each substance in component A and component B separately until homogeneous, ensuring that the two components do not interfere with each other.

[0027] The third aspect of this application provides the application of the aforementioned negative electrode reinforcing composition in the preparation of artificial graphite, wherein the negative electrode reinforcing composition is mixed with carbon micropowder and pressed into carbon particles. Using this negative electrode reinforcing composition mixed with carbon micropowder and pressed, carbon particles exhibiting a good strength curve and low levels of high melting point, high volatility, metallic elemental impurities, and compound impurities can be obtained.

[0028] As one technical solution of this application, the mass ratio of the negative electrode enhancement composition to the carbon micro powder is 5-35:50-100.

[0029] As a technical solution of this application, the carbon micro powder is first mixed with the component A, then the component B is added by spraying and mixed, and then pressed to obtain the carbon particles. The carbon particles are then dried, baked, carbonized and graphitized in sequence to obtain artificial graphite.

[0030] As a technical solution of this application, the initial free fall fracture resistance of the carbon particles is 300mm to 800mm, the free fall fracture resistance after drying and baking is 400mm to 1300mm, the free fall fracture resistance after carbonization is 350mm to 700mm, and the free fall fracture resistance after graphitization is 150mm to 450mm. Attached Figure Description

[0031] Figure 1 is a SEM image of the artificial graphite prepared using the composition of Example 1.

[0032] Figure 2 is a SEM image of the artificial graphite prepared using the composition of Example 2.

[0033] Figure 3 is a SEM image of the artificial graphite prepared using the composition of Example 3.

[0034] Figure 4 is a SEM image of the artificial graphite prepared using the composition of Comparative Example 5. Detailed Implementation

[0035] This application provides a negative electrode enhancement composition, a preparation method, and an application. By mixing and pressing this negative electrode enhancement composition with carbon micropowder, carbon particles exhibiting a good strength curve and low levels of high melting point, high volatility, metallic impurities, and compounds can be obtained, which is beneficial for the industrialization of vertical continuous graphitization processes.

[0036] The negative electrode enhancement composition of this application includes component A and component B.

[0037] The raw materials for preparing component A include asphalt powder, polyvinyl alcohol powder, redispersible polymer powder, and phenolic resin powder in a mass ratio of 10-90:10-90:0-10:0-40.

[0038] The mass ratio of asphalt powder can be, but is not limited to, 10, 20, 30, 40, 50, 60, 70, 80, or 90. The particle size of the asphalt powder is from 0.01 μm to 80.00 μm, and the particle size can be, but is not limited to, 0.01 μm, 0.10 μm, 1.00 μm, 5.00 μm, 10.00 μm, 20.00 μm, 30.00 μm, 40.00 μm, 50.00 μm, 60.00 μm, 70.00 μm, or 80.00 μm.

[0039] The mass ratio of polyvinyl alcohol powder can be, but is not limited to, 10, 20, 30, 40, 50, 60, 70, 80, or 90. The particle size of the polyvinyl alcohol powder is from 0.01 μm to 100.00 μm, and the particle size of the asphalt powder can be, but is not limited to, 0.01 μm, 0.10 μm, 1.00 μm, 5.00 μm, 10.00 μm, 20.00 μm, 30.00 μm, 40.00 μm, 50.00 μm, 60.00 μm, 70.00 μm, 80.00 μm, 90.00 μm, or 100.00 μm. The polyvinyl alcohol powder comprises at least two polyvinyl alcohols with different degrees of polymerization. As a technical solution of this application, the polyvinyl alcohol powder includes PVA1788 and PVA2488. The combined use of PVA1788 and PVA2488 not only provides suitable free-fall fracture resistance for carbon particles, but also allows for adjustment of the viscosity during subsequent mixing and pressing with carbon micropowder, thanks to the different degrees of polymerization of PVA1788 and PVA2488. This ensures the quality of the briquettes and smooth operation of the pressing process, preventing the carbon particles from easily breaking due to excessively low viscosity and sticking to the molds during pressing due to excessively high viscosity, which would hinder the pressing process. The combined use of PVA1788 and PVA2488 also overcomes the adverse effects of numerous small air bubbles generated and incorporated during mixing with carbon micropowder on the quality of the carbon particles and the resulting artificial graphite.

[0040] The mass ratio of the redispersible polymer powder can be, but is not limited to, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10. The particle size of the redispersible polymer powder is from 0.01 μm to 80.00 μm, and the particle size can be, but is not limited to, 0.01 μm, 0.10 μm, 1.00 μm, 5.00 μm, 10.00 μm, 20.00 μm, 30.00 μm, 40.00 μm, 50.00 μm, 60.00 μm, 70.00 μm, or 80.00 μm.

[0041] The mass ratio of phenolic resin powder can be, but is not limited to, 0, 5, 10, 15, 20, 25, 30, 35, or 40. The particle size of the phenolic resin powder is from 0.01 μm to 80.00 μm, and the particle size can be, but is not limited to, 0.01 μm, 0.10 μm, 1.00 μm, 5.00 μm, 10.00 μm, 20.00 μm, 30.00 μm, 40.00 μm, 50.00 μm, 60.00 μm, 70.00 μm, or 80.00 μm.

[0042] Component B comprises an aqueous solution containing calcium chloride and hydrochloric acid. The raw materials for preparing Component B include an aqueous solution of calcium chloride, hydrochloric acid, and water in a mass ratio of 20–60:1–20:40–80. The mass ratio of the calcium chloride aqueous solution can be, but is not limited to, 20, 25, 30, 35, 40, 45, 50, 55, or 60. The amount of calcium chloride in the aqueous solution should preferably be 0.3% to 4.0% of the mass of the carbon micropowder. Too little calcium chloride will not effectively lower the eutectic point, while too much will waste the energy required for gasification. The amount of hydrochloric acid added should not be too much, otherwise it will waste raw materials and cause equipment corrosion; however, it should not be too little either, otherwise it will not be able to completely transform high-melting-point, high-boiling-point metallic elements and compound impurities into low-melting-point, low-boiling-point metallic elements and compound impurities. The mass concentration of the calcium chloride aqueous solution is 2% to 50%, and may be, but is not limited to, 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, and 50%. The molar concentration of hydrochloric acid is 0.01 mol / L to 5.00 mol / L, and may be, but is not limited to, 0.01 mol / L, 0.05 mol / L, 0.10 mol / L, 0.50 mol / L, 1.00 mol / L, 2.00 mol / L, 3.00 mol / L, 4.00 mol / L, and 5.00 mol / L.

[0043] The mass ratio of component A to component B is 1 to 8:7 to 28. The mass ratio of the two components can be, but is not limited to, 1:7, 1:10, 1:15, 1:20, 1:25, 3:6, 3:10, 3:15, 3:20, 3:25, 5:6, 5:10, 5:15, 5:20, 5:25, 8:6, 8:10, 8:15, 8:20, 8:25, and 8:28.

[0044] The negative electrode enhancement composition of this application can be prepared by weighing each substance in component A according to the formula amount, mixing them evenly in a first mixer, and then storing and storing it for later use; and by weighing each substance in component B according to the formula amount, mixing them evenly in a second mixer, and then storing it for later use. The first mixer can be a ribbon mixer, a single-cone double-helix mixer, a horizontal plow mixer, or a mortar mixer. As a technical solution of this application, the first mixer is a single-cone double-helix mixer. The mixing speed of the first mixer is from 30 r / min to 200 r / min, and can be, but is not limited to, 30 r / min, 50 r / min, 80 r / min, 100 r / min, 120 r / min, 150 r / min, 180 r / min, or 200 r / min. The mixing time of the first mixer is 2 to 15 minutes, but is not limited to 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 minutes. The second mixer is a liquid mixing mixer; for example, the second mixer is a liquid mixing mixer with an acid resistance pH value ≥ 1. The mixing speed of the second mixer is 30 to 180 rpm, but is not limited to 30, 50, 80, 100, 120, 150, or 180 rpm. The mixing time of the second mixer is 2 to 5 minutes, but is not limited to 2, 3, 4, or 5 minutes.

[0045] The negative electrode reinforcing composition of this application is used in the preparation of artificial graphite. The process may include mixing the negative electrode reinforcing composition and carbon micropowder and pressing them into carbon particles. Further, the process includes first mixing the carbon micropowder with component A, then spraying in component B for mixing, pressing to obtain carbon particles, and then sequentially drying, carbonizing, and graphitizing the carbon particles to obtain artificial graphite.

[0046] The mass ratio of the negative electrode reinforcing composition to the carbon micro powder is 5-35:50-100, and may be, but is not limited to, 5:50, 5:60, 5:70, 5:80, 5:90, 5:100, 15:50, 15:60, 15:70, 15:80, 15:90, 15:100, 25:50, 25:60, 25:70, 25:80, 25:90, 25:100, 35:50, 35:60, 35:70, 35:80, 35:90, or 35:100.

[0047] Carbon micropowder can be obtained by pretreating the carbon source.

[0048] The carbon source includes coke powder and / or graphite powder. Coke powder includes one or more of needle coke, calcined petroleum coke, raw petroleum coke, semi-calcined petroleum coke, pitch coke, anthracite, and biochar. Of course, the carbon source may also include more than just the above-mentioned substances. Graphite powder includes at least one of flake graphite, microcrystalline graphite, and spherical graphite. The median particle size of the carbon source is 5 μm to 25 μm, and may be, but is not limited to, 5 μm, 8 μm, 10 μm, 13 μm, 15 μm, 18 μm, 20 μm, 22 μm, 24 μm, and 25 μm. The carbon content of the carbon source is ≥85 wt.%, and may be, but is not limited to, ≥85 wt.%, ≥86 wt.%, ≥87 wt.%, ≥88 wt.%, ≥89 wt.%, and ≥94 wt.%. The volatile matter content of the carbon source ranges from 0.1% to 15.0%, and may include, but is not limited to, 0.1%, 0.5%, 1.0%, 2.0%, 3.0%, 4.0%, 6.0%, 8.0%, 10.0%, 12.0%, 14.0%, and 15.0%. The sulfur content of the carbon source ranges from 0.1% to 3.5%, and may include, but is not limited to, 0.1%, 1.5%, 2.0%, 2.5%, and 3.5%.

[0049] The pretreatment process involves pulverizing the carbon source to a particle size of 0.01 mm to 5.00 mm, followed by grinding to obtain carbon micropowder with a particle size of 5 μm to 20 μm. The particle size of the obtained carbon micropowder can be, but is not limited to, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, and 20 μm. The carbon source can be a single source or a mixture of multiple sources. The carbon sources are mixed uniformly to ensure consistent particle size, volatile matter, and carbon or impurity content, facilitating the control of pulverization and grinding parameters to obtain uniform carbon micropowder. Uniform carbon micropowder, with its largely consistent properties, facilitates the stable control of additives and allows for the pressing of carbon particles with stable quality. Stable carbon particles will not exhibit fluctuations in strength, preventing low-strength particles from easily breaking and pulverizing, which would hinder subsequent drying and graphitization. Conversely, excessively strong carbon particles will not break down after graphitization, requiring further crushing and grinding, resulting in undesirable outcomes such as rough product surface, low compaction density, and excessively large specific surface area.

[0050] The uniformly mixed carbon source is continuously and automatically fed into a pulverizer, where it is pulverized to a particle size of 0.01 mm to 5.00 mm. Particle sizes can be, but are not limited to, 0.01 mm, 0.05 mm, 0.10 mm, 0.5 mm, 1.00 mm, 2.00 mm, 3.00 mm, 4.00 mm, and 5.00 mm. Pulverizing too finely results in excessively fine carbon micropowder, leading to a low yield of qualified products. Pulverizing too coarsely results in excessively large carbon micropowder particles, causing low grinding efficiency. The resulting carbon micropowder has a relatively rounded surface, resembling millet, sesame seeds, or olives, forming a spherical shape. Compared to irregularly shaped carbon micropowder with a rough surface, this structure results in a higher tap density and smaller specific surface area, leading to a higher volumetric energy density in the resulting anode material.

[0051] The carbon micropowder and component A are mixed using a mixer, which may include a ribbon mixer, a single-cone double-spiral mixer, a horizontal plow mixer, or a mortar mixer. As an example, a single-cone double-spiral mixer with an acid resistance pH value ≥ 1 is selected, as this type of mixer facilitates rapid and uniform mixing of the materials. The mixing speed of the mixer is from 30 r / min to 200 r / min, and may include, but is not limited to, 30 r / min, 50 r / min, 70 r / min, 90 r / min, 100 r / min, 120 r / min, 140 r / min, 160 r / min, 180 r / min, and 200 r / min. The mixing time is from 2 min to 15 min, and may include, but is not limited to, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 12 min, 13 min, and 15 min.

[0052] Component B is added via spraying. Spraying avoids wet lumps or uneven drying, improving the yield of the pressed carbon particles. The spraying speed is from 1.0 kg / min to 10.0 kg / min, but is not limited to 1.0 kg / min, 1.5 kg / min, 2.5 kg / min, 3.5 kg / min, 4.5 kg / min, 5.5 kg / min, 6.5 kg / min, 7.5 kg / min, 8.5 kg / min, 9.5 kg / min, and 10.0 kg / min. The nozzles can be installed on a mixer, which can have 1 to 8 nozzles. Spraying facilitates uniform mixing of the components. After adding component B, the mixing speed of the mixer is 60 r / min to 270 r / min, but not limited to 60 r / min, 80 r / min, 100 r / min, 120 r / min, 150 r / min, 180 r / min, 200 r / min, 220 r / min, 240 r / min, 260 r / min, and 270 r / min. The mixing time is 3 min to 8 min, but not limited to 3 min, 4 min, 5 min, 6 min, 7 min, and 8 min. After adding component B, the material is placed in an acid-resistant buffer chamber for pressing.

[0053] In addition to carbon, carbon micropowder also contains impurities with high melting and high volatility, such as Fe2O3, Fe, CaO, SiO2, and CaSiO4, as shown in Table 1. These high-melting-point and high-volatility-point metallic elements and compounds not only accumulate and form coke caking in the vertical graphitization furnace, posing a safety hazard of pressure injection, but also react with the carbon in the carbon micropowder, causing carbon loss, as shown in the following equation: 2Fe2O3 + 3C = 4Fe + 3CO2↑

[0054] Table 1. Composition content of carbon micro powder

[0055] Hydrochloric acid can react with high-melting-point and high-volatility-point metallic elements and metallic compound impurities, transforming them into low-melting-point and low-boiling-point metallic elements and metallic compounds. For example, Fe₂O₃ (melting point 1565℃, boiling point 3414℃) and metallic Fe (boiling point 2750℃) can be converted into FeCl₃ (melting point 306℃, boiling point 319℃); CaO can be converted into CaCl₂; Co (boiling point 3100℃) into CoCl₂ (boiling point 1049℃); and Cr₂O₃ (boiling point 4000℃) into CrCl₃ (boiling point 1300℃). The amount of hydrochloric acid added is controlled to maintain the acidity of the carbon micropowder at 5.5 to 6.9, but not limited to 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, and 6.9. The acidity value of 5.5 to 6.9 is slightly acidified in order to use a very small amount of hydrochloric acid to convert the high melting point and high volatility point impurities in the carbon micropowder into low melting point and low volatility point impurities.

[0056] The pressing process involves first buffering the mixed materials and then pressing them into briquettes in a briquetting machine to obtain carbon particles with a particle size of 5mm to 30mm. The particle size can be, but is not limited to, 5mm, 10mm, 15mm, 20mm, 25mm, and 30mm. The particle size of the carbon particles should not be uniform, as this is detrimental to furnace resistance adjustment in the vertical continuous graphitization process. At the same time, the particle size distribution should not be too large, otherwise it can easily cause excessive deviation in the downward movement speed of the particles in the vertical graphitization furnace, leading to unstable graphitization index of the product. Therefore, as an example, the carbon particles can include a combination of carbon particles with multiple particle sizes, such as the first carbon particle having a particle size of 5mm to 10mm, the second carbon particle having a particle size of 10mm to 20mm, the third carbon particle having a particle size of 20mm to 30mm, and the fourth carbon particle having a particle size of 30mm to 35mm, with the ratio of the first, second, third, and fourth carbon particles being 10–60:30–80:20–60:0–30. The mixed materials are then subjected to a pressing and buffering process. The buffering pressure is controlled between -0.001 kPa and -30.0 kPa, but is not limited to -0.001 kPa, -0.01 kPa, -0.10 kPa, -1.0 kPa, -5.0 kPa, -10.0 kPa, -15.0 kPa, -20.0 kPa, -25.0 kPa, and -30.0 kPa. The buffering time is 10 to 30 minutes. Excessive buffering time can lead to liquid evaporation and material drying, affecting the quality of the briquettes. Negative pressure is used during buffering to expel gas from the pores or grooves of the carbon micropowder. This allows the asphalt powder, polyvinyl alcohol powder, redispersible polymer powder, or phenolic resin powder to penetrate and fully wet the pores or grooves, improving coating and bonding quality. Furthermore, most of the gas between the carbon micropowder particles is removed, which helps improve the density and initial strength of the carbon micropowder. The prepared material is fed into a briquetting machine for briquetting. The briquetting pressure is between 0.5 MPa and 5.0 MPa, using a continuous pressing method without pressure holding. The pressure can be, but is not limited to, 0.5 MPa, 1.0 MPa, 1.5 MPa, 2.0 MPa, 2.5 MPa, 3.0 MPa, 3.5 MPa, 4.0 MPa, 4.5 MPa, and 5.0 MPa. The briquetting pressure should not be too low, otherwise it will be difficult to form compact carbon particles. Similarly, the pressure should not be too high, otherwise the particles obtained from subsequent graphitization will be difficult to disperse, adversely affecting the product's appearance and tap density.

[0057] Carbon particles can be dried at 150℃ to 250℃ to a moisture content of less than 0.01 wt.%. The drying process can be performed by a single heating to 150℃ to 250℃, or by first drying in a gradient from 30℃ to 105℃, followed by a gradient baking from 105℃ to 300℃. The drying temperatures can be, but are not limited to, 150℃, 175℃, 200℃, 210℃, 220℃, 230℃, 240℃, and 250℃. Drying allows the thermosetting and fusible components in the carbon particles to melt and solidify, facilitating the formation of a stable structure, maintaining good mechanical strength, and improving the stability and safety of subsequent graphitization.

[0058] The equipment for drying, carbonization, and graphitization can be an integrated structure, or the carbonization and graphitization equipment can be an integrated structure. An integrated structure for drying, carbonization, and graphitization significantly reduces heat loss and ensures the strength and integrity of the particles; it also avoids damage or pulverization caused by intermittent operation. The integrated drying, carbonization, and graphitization equipment can be a single machine that sequentially integrates the functions of drying, carbonization, and graphitization, or the inlets and outlets of the drying machine, carbonization machine, and graphitization machine can be connected sequentially, thus avoiding losses caused by material transfer. The drying and carbonization machines can be conventional machines, and the graphitization machine can be a conventional vertical continuous graphitization machine, as long as all three functions can be integrated into one unit. The integrated continuous process of carbonization and graphitization can achieve a micro-positive pressure self-oxygen barrier system at the furnace top through the volatile gases generated during carbonization and the gaseous substances overflowing from the graphitization purification process. It does not require the introduction of a large amount of inert gas for oxygen barrier protection, which can reduce equipment investment and operating costs. In particular, it avoids the introduction of a large amount of N2, eliminating the investment and operating costs of denitrification.

[0059] The carbonization temperature is between 700℃ and 1500℃, but not limited to 700℃, 800℃, 900℃, 1000℃, 1100℃, 1200℃, 1300℃, 1400℃, and 1500℃. The carbonization time is between 10h and 80h, but not limited to 10h, 20h, 30h, 40h, 50h, 60h, 70h, and 80h. The carbonization is carried out under a non-oxidizing atmosphere.

[0060] The temperature for vertical continuous graphitization is 2200℃ to 3300℃, but can be, but is not limited to, 2200℃, 2300℃, 2400℃, 2500℃, 2600℃, 2700℃, 2800℃, 2900℃, 3000℃, 3100℃, 3200℃, and 3300℃. The time for vertical continuous graphitization is 8h to 36h, but can be, but is not limited to, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, 26h, 28h, 30h, 32h, 34h, and 36h. Vertical continuous graphitization is carried out under non-oxidizing atmosphere conditions. The non-oxidizing atmosphere conditions are such that a portion of the gas overflowing from graphitization flows into the feed channel and is discharged in the opposite direction to the material, preventing oxygen from entering the furnace chamber from the feed port. The differential pressure at the gas outlet is set to 0 Pa to ±30 Pa, and can be, but is not limited to, 0 Pa, 2 Pa, 4 Pa, 6 Pa, 8 Pa, 10 Pa, 12 Pa, 14 Pa, 16 Pa, 18 Pa, 20 Pa, 22 Pa, 24 Pa, 26 Pa, 28 Pa, and 30 Pa. The furnace bottom adopts a double-feed cup double-closed valve combined with a negative pressure device to prevent oxygen from entering the furnace chamber from the discharge port. The power of vertical continuous graphitization is adjustable from 400KW to 1950KW.

[0061] After graphitization, the powder can be further dispersed and graded to a particle size of 5μm to 30μm. For example, the particle size can be, but is not limited to, 5μm, 10μm, 15μm, 20μm, 25μm, and 30μm. By dispersing the graphitized powder without crushing or grinding, the sphericity, morphology, stable specific surface area, and tap density of the product are effectively protected, while preventing the introduction of iron and eliminating the need for further demagnetization at the end of the process.

[0062] By mixing and pressing the negative electrode reinforcing composition of this application with carbon micropowder, carbon particles with an initial free-fall fracture resistance value of 300 mm to 800 mm can be obtained. Carbon particles with this strength will not break during the conveying and drying process. After drying and baking, the free-fall fracture resistance value is 400 mm to 1300 mm, the strength is improved and will not be damaged during the conveying and carbonization process. After carbonization, the free-fall fracture resistance value is 350 mm to 700 mm. At this strength, the particles will not break or leak during the conveying and graphitization heat treatment process. Finally, after graphitization, the free-fall fracture resistance value is 150 mm to 450 mm. At this strength, the graphitized particles can be easily dispersed, and the resulting artificial graphite products can obtain good appearance morphology and tap density.

[0063] The method for determining the free-fall fracture resistance value is as follows.

[0064] (1) Place the test apparatus, which consists of a base, a support rod, and a particle placement rack. The base is made of a steel plate with a thickness of 10 mm × 100 mm × 100 mm. The support rod is a steel pipe with a diameter of 8 mm and a length of 1500 mm. The steel pipe is perpendicularly connected to the steel plate through threads, and the steel pipe is marked with scales from 0 mm to 1300 mm upward from the upper plane of the steel plate. The particle placement rack has a particle placement ring, and a horizontally movable support plate is provided at the bottom of the particle placement ring. The particle placement ring can be moved up and down freely on the support rod and is connected and fixed to the support rod by screws.

[0065] (2) Place the particles. Fix the particle placement ring at the selected height and tighten it. Place the support plate directly below the particle placement ring, and then put the complete particles into the particle placement ring and on the support plate;

[0066] (3) Free-fall operation. Move the support plate left or right to remove it, and the particles on the support plate will fall freely and hit the upper surface of the base.

[0067] (4) Check the state result of the free fall of the particles to evaluate and obtain the anti-breakage strength value of the free fall of the particles. When testing at each lower limit height, the free-falling particles are complete and not broken. At the same time, when testing at each upper limit height + 1 mm, the free-falling particles are incomplete and broken, which is considered qualified. For example, for the anti-breakage strength value of 300 mm free fall, after the pressed carbon balls are allowed to fall freely at 300 mm, observe whether they are broken. If not broken, it means it is qualified, and its anti-breakage strength value is at least 300 mm. If broken, it means the maximum anti-breakage strength value is 300 mm.

[0068] To better illustrate the purpose, technical solution, and beneficial effects of the present application, the present application will be further described below in conjunction with specific embodiments. It should be noted that the following described methods of the embodiments are further explanatory descriptions of the present application and should not be regarded as limitations to the present application.

[0069] Example 1

[0070] This example is a negative electrode enhancing composition, including component A and component B. The mass ratio of component A to component B is 5:10.

[0071] The preparation raw materials of component A include asphalt powder, PVA1788, PVA2488, and redispersible powder in a mass ratio of 60:5:30:5. The particle size of the asphalt powder is 20.00 μm, the particle sizes of PVA1788 and PVA2488 are 40.00 μm, and the particle size of the redispersible powder is 60.00 μm. Weigh the asphalt powder, PVA1788, PVA2488, and redispersible powder according to the formula amount and mix them in a single-cone double-screw mixer at a rotation speed of 60 r / min for 5 min, then store and reserve them.

[0072] Component B comprises a calcium chloride aqueous solution, hydrochloric acid, and water in a mass ratio of 60:10:40. The calcium chloride aqueous solution has a mass concentration of 50%, and the hydrochloric acid has a molar concentration of 0.20 mol / L. Weigh the calcium chloride aqueous solution, hydrochloric acid, and water according to the formula, and mix them in a general-purpose liquid mixer with an acid-resistant pH value ≥1 at a speed of 60 r / min for 3 minutes, then store for later use.

[0073] Example 2

[0074] This embodiment is a negative electrode enhancement composition, comprising component A and component B. The mass ratio of component A to component B is 4.62:10.

[0075] The raw materials for preparing component A include asphalt powder, PVA1788, PVA2488, redispersible polymer powder, and phenolic resin powder in a mass ratio of 50:8:27:5:10. The particle size of the asphalt powder is 20.00 μm, the particle size of PVA1788 and PVA2488 is 40.00 μm, the particle size of the redispersible polymer powder is 60.00 μm, and the particle size of the phenolic resin powder is 70.00 μm. The asphalt powder, PVA1788, PVA2488, redispersible polymer powder, and phenolic resin powder are weighed according to the formula and mixed in a single-cone double-spiral mixer at a speed of 60 r / min for 5 min, then stored for later use.

[0076] Component B comprises a calcium chloride aqueous solution, hydrochloric acid, and water in a mass ratio of 60:8:42. The calcium chloride aqueous solution has a mass concentration of 45%, and the hydrochloric acid has a molar concentration of 0.30 mol / L. The calcium chloride aqueous solution, hydrochloric acid, and water are weighed according to the formula and mixed in a general-purpose liquid mixer with an acid-resistant pH value ≥1 at a speed of 60 r / min for 3 minutes, then stored for later use.

[0077] Example 3

[0078] This embodiment is a negative electrode enhancement composition, comprising component A and component B. The mass ratio of component A to component B is 3.85:10.

[0079] The raw materials for preparing component A include asphalt powder, PVA1788, PVA2488, and redispersible polymer powder in a mass ratio of 60:10:25:5. The particle size of the asphalt powder is 20.00 μm, the particle size of PVA1788 and PVA2488 is 40.00 μm, and the particle size of the redispersible polymer powder is 60.00 μm. The asphalt powder, PVA1788, PVA2488, and redispersible polymer powder are weighed according to the formula and mixed in a single-cone double-screw mixer at a speed of 60 r / min for 5 min, then stored for later use.

[0080] Component B comprises a calcium chloride aqueous solution, hydrochloric acid, and water in a mass ratio of 58:10:42. The calcium chloride aqueous solution has a mass concentration of 50%, and the hydrochloric acid has a molar concentration of 0.25 mol / L. The calcium chloride aqueous solution, hydrochloric acid, and water are weighed according to the formula and mixed in a general-purpose liquid mixer with an acid-resistant pH value ≥1 at a speed of 60 r / min for 3 minutes, then stored for later use.

[0081] Example 4

[0082] This embodiment is a negative electrode enhancement composition, comprising component A and component B. The mass ratio of component A to component B is 5:10.

[0083] The raw materials for preparing component A include asphalt powder, PVA1788, and PVA2488 in a mass ratio of 60:5:30. The particle size of the asphalt powder is 20.00 μm, and the particle sizes of PVA1788 and PVA2488 are 40.00 μm. The asphalt powder, PVA1788, and PVA2488 are weighed according to the formula and mixed in a single-cone double-screw mixer at a speed of 60 r / min for 5 min, then stored for later use.

[0084] Component B comprises a calcium chloride aqueous solution, hydrochloric acid, and water in a mass ratio of 60:10:40. The calcium chloride aqueous solution has a mass concentration of 50%, and the hydrochloric acid has a molar concentration of 0.20 mol / L. Weigh the calcium chloride aqueous solution, hydrochloric acid, and water according to the formula, and mix them in a general-purpose liquid mixer with an acid-resistant pH value ≥1 at a speed of 60 r / min for 3 minutes, then store for later use.

[0085] Example 5

[0086] This embodiment is a negative electrode enhancement composition, comprising component A and component B. The mass ratio of component A to component B is 5:10.

[0087] The raw materials for preparing component A include asphalt powder, PVA1788, PVA2488, and phenolic resin powder in a mass ratio of 60:5:30:5. The particle size of the asphalt powder is 20.00 μm, the particle size of PVA1788 and PVA2488 is 40.00 μm, and the particle size of the phenolic resin powder is 70.00 μm. The asphalt powder, PVA1788, PVA2488, and phenolic resin powder are weighed according to the formula and mixed in a single-cone double-spiral mixer at a speed of 60 r / min for 5 min, then stored for later use.

[0088] Component B comprises a calcium chloride aqueous solution, hydrochloric acid, and water in a mass ratio of 60:10:40. The calcium chloride aqueous solution has a mass concentration of 50%, and the hydrochloric acid has a molar concentration of 0.20 mol / L. Weigh the calcium chloride aqueous solution, hydrochloric acid, and water according to the formula, and mix them in a general-purpose liquid mixer with an acid-resistant pH value ≥1 at a speed of 60 r / min for 3 minutes, then store for later use.

[0089] Example 6

[0090] This embodiment is a negative electrode enhancement composition, comprising component A and component B. The mass ratio of component A to component B is 5:10.

[0091] The raw materials for preparing component A include asphalt powder, PVA1788, PVA2488, phenolic resin powder, and redispersible polymer powder in a mass ratio of 60:5:30:5:10. The particle size of the asphalt powder is 20.00 μm, the particle size of PVA1788 and PVA2488 is 40.00 μm, the particle size of the phenolic resin powder is 70.00 μm, and the particle size of the redispersible polymer powder is 60.00 μm. The asphalt powder, PVA1788, PVA2488, phenolic resin powder, and redispersible polymer powder are weighed according to the formula and mixed in a single-cone double-spiral mixer at a speed of 60 r / min for 5 min, then stored for later use.

[0092] Component B comprises a calcium chloride aqueous solution, hydrochloric acid, and water in a mass ratio of 60:10:40. The calcium chloride aqueous solution has a mass concentration of 50%, and the hydrochloric acid has a molar concentration of 0.20 mol / L. Weigh the calcium chloride aqueous solution, hydrochloric acid, and water according to the formula, and mix them in a general-purpose liquid mixer with an acid-resistant pH value ≥1 at a speed of 60 r / min for 3 minutes, then store for later use.

[0093] Example 7

[0094] This embodiment is a negative electrode enhancement composition, comprising component A and component B. The mass ratio of component A to component B is 5:10.

[0095] The raw materials for preparing component A include asphalt powder, PVA1788, and redispersible polymer powder in a mass ratio of 60:35:5. The particle size of the asphalt powder is 20.00 μm, the particle size of PVA1788 is 40.00 μm, and the particle size of the redispersible polymer powder is 60.00 μm. The asphalt powder, PVA1788, and redispersible polymer powder are weighed according to the formula and mixed in a single-cone double-screw mixer at a speed of 60 r / min for 5 min, then stored for later use.

[0096] Component B comprises a calcium chloride aqueous solution, hydrochloric acid, and water in a mass ratio of 60:10:40. The calcium chloride aqueous solution has a mass concentration of 50%, and the hydrochloric acid has a molar concentration of 0.20 mol / L. Weigh the calcium chloride aqueous solution, hydrochloric acid, and water according to the formula, and mix them in a general-purpose liquid mixer with an acid-resistant pH value ≥1 at a speed of 60 r / min for 3 minutes, then store for later use.

[0097] Example 8

[0098] This embodiment is a negative electrode enhancement composition, comprising component A and component B. The mass ratio of component A to component B is 5:10.

[0099] The raw materials for preparing component A include asphalt powder, PVA2488, and redispersible polymer powder in a mass ratio of 60:35:5. The particle size of the asphalt powder is 20.00 μm, the particle size of PVA2488 is 40.00 μm, and the particle size of the redispersible polymer powder is 60.00 μm. The asphalt powder, PVA2488, and redispersible polymer powder are weighed according to the formula and mixed in a single-cone double-screw mixer at a speed of 60 r / min for 5 min, then stored for later use.

[0100] Component B comprises a calcium chloride aqueous solution, hydrochloric acid, and water in a mass ratio of 60:10:40. The calcium chloride aqueous solution has a mass concentration of 50%, and the hydrochloric acid has a molar concentration of 0.20 mol / L. Weigh the calcium chloride aqueous solution, hydrochloric acid, and water according to the formula, and mix them in a general-purpose liquid mixer with an acid-resistant pH value ≥1 at a speed of 60 r / min for 3 minutes, then store for later use.

[0101] Example 9

[0102] This embodiment is a negative electrode enhancement composition, comprising component A and component B. The mass ratio of component A to component B is 5:10.

[0103] The raw materials for preparing component A include asphalt powder, PVA1788, PVA2488, and redispersible polymer powder in a mass ratio of 60:5:30:5. The particle size of the asphalt powder is 50.00 μm, the particle size of PVA1788 and PVA2488 is 55.00 μm, and the particle size of the redispersible polymer powder is 40.00 μm. The asphalt powder, PVA1788, PVA2488, and redispersible polymer powder are weighed according to the formula and mixed in a single-cone double-helix mixer at a speed of 100 r / min for 3 min, then stored for later use.

[0104] Component B comprises a calcium chloride aqueous solution, hydrochloric acid, and water in a mass ratio of 60:10:40. The calcium chloride aqueous solution has a mass concentration of 50%, and the hydrochloric acid has a molar concentration of 0.20 mol / L. Weigh the calcium chloride aqueous solution, hydrochloric acid, and water according to the formula, and mix them in a general-purpose liquid mixer with an acid-resistant pH value ≥1 at a speed of 80 r / min for 2 min, then store for later use.

[0105] Example 10

[0106] This embodiment is a negative electrode enhancement composition, comprising component A and component B. The mass ratio of component A to component B is 5:10.

[0107] The raw materials for preparing component A include asphalt powder, PVA1788, PVA2488, redispersible polymer powder, and phenolic resin powder in a mass ratio of 20:10:35:8:20. The particle size of the asphalt powder is 20.00 μm, the particle size of PVA1788 and PVA2488 is 40.00 μm, the particle size of the redispersible polymer powder is 60.00 μm, and the particle size of the phenolic resin powder is 70.00 μm. The asphalt powder, PVA1788, PVA2488, redispersible polymer powder, and phenolic resin powder are weighed according to the formula and mixed in a ribbon mixer at a speed of 70 r / min for 6 min, then stored for later use.

[0108] Component B comprises a calcium chloride aqueous solution, hydrochloric acid, and water in a mass ratio of 30:15:55. The calcium chloride aqueous solution has a mass concentration of 25%, and the hydrochloric acid has a molar concentration of 3.00 mol / L. The calcium chloride aqueous solution, hydrochloric acid, and water are weighed according to the formula and mixed in a general-purpose liquid mixer with an acid-resistant pH value ≥1 at a speed of 50 r / min for 5 min, then stored for later use.

[0109] Comparative Example 1

[0110] This comparative example is a negative electrode enhancement composition, comprising component A and component B. The mass ratio of component A to component B is 5:10.

[0111] The raw material for preparing component A includes corn starch with a particle size of 20.00 μm. The corn starch was mixed in a single-cone double-spiral mixer at a speed of 60 r / min for 5 min and then stored for later use.

[0112] Component B is water. Mix the water in a general-purpose liquid mixer with an acid resistance pH value ≥ 1 at a speed of 60 r / min for 3 minutes, then store and use it for later use.

[0113] Comparative Example 2

[0114] This comparative example is a negative electrode enhancement composition, comprising component A and component B. The mass ratio of component A to component B is 5:10.

[0115] The raw material for preparing component A includes cassava starch with a particle size of 20.00 μm. The cassava starch was mixed in a single-cone double-helix mixer at a speed of 60 r / min for 5 min and then stored for later use.

[0116] Component B is water. Mix the water in a general-purpose liquid mixer with an acid resistance pH value ≥ 1 at a speed of 60 r / min for 3 minutes, then store and use it for later use.

[0117] Comparative Example 3

[0118] This comparative example is a negative electrode enhancement composition, comprising component A and component B. The mass ratio of component A to component B is 5:10.

[0119] The raw material for preparing component A includes corn starch with a particle size of 20.00 μm. The corn starch was mixed in a single-cone double-spiral mixer at a speed of 60 r / min for 5 min and then stored for later use.

[0120] Component B comprises a PVA aqueous solution and water in a mass ratio of 60:40. The mass concentration of the PVA aqueous solution is 10%. Weigh the PVA aqueous solution and water according to the formula and mix them in a general-purpose liquid mixer with an acid-resistant pH value ≥1 at a speed of 60 r / min for 3 minutes, then store for later use.

[0121] Comparative Example 4

[0122] This comparative example is a negative electrode enhancement composition, comprising component A and component B. The mass ratio of component A to component B is 5:10.

[0123] The raw material for preparing component A includes cassava starch with a particle size of 20.00 μm. The cassava starch was mixed in a single-cone double-helix mixer at a speed of 60 r / min for 5 min and then stored for later use.

[0124] Component B comprises a PVA aqueous solution and water in a mass ratio of 60:40. The mass concentration of the PVA aqueous solution is 10%. Weigh the PVA aqueous solution and water according to the formula and mix them in a general-purpose liquid mixer with an acid-resistant pH value ≥1 at a speed of 60 r / min for 3 minutes, then store for later use.

[0125] Comparative Example 5

[0126] This comparative example is a negative electrode enhancement composition, comprising component A and component B. The mass ratio of component A to component B is 10:10.

[0127] The raw materials for preparing component A include PVA1788 and PVA2488 in a mass ratio of 5:30. The particle size of PVA1788 and PVA2488 is 40.00 μm. PVA1788 and PVA2488 are weighed according to the formula and mixed in a single-cone double-helix mixer at a speed of 60 r / min for 5 min, then stored for later use.

[0128] Component B comprises a calcium chloride aqueous solution, hydrochloric acid, and water in a mass ratio of 60:10:40. The calcium chloride aqueous solution has a mass concentration of 50%, and the hydrochloric acid has a molar concentration of 0.20 mol / L. Weigh the calcium chloride aqueous solution, hydrochloric acid, and water according to the formula, and mix them in a general-purpose liquid mixer with an acid-resistant pH value ≥1 at a speed of 60 r / min for 3 minutes, then store for later use.

[0129] Comparative Example 6

[0130] This comparative example is a negative electrode enhancement composition, comprising component A and component B. The mass ratio of component A to component B is 5:10.

[0131] The raw material for preparing component A is asphalt powder with a particle size of 20.00 μm. The asphalt powder is weighed and mixed in a single-cone double-helix mixer at a speed of 60 r / min for 5 min, then stored for later use.

[0132] Component B comprises a calcium chloride aqueous solution, hydrochloric acid, and water in a mass ratio of 60:10:40. The calcium chloride aqueous solution has a mass concentration of 50%, and the hydrochloric acid has a molar concentration of 0.20 mol / L. Weigh the calcium chloride aqueous solution, hydrochloric acid, and water according to the formula, and mix them in a general-purpose liquid mixer with an acid-resistant pH value ≥1 at a speed of 60 r / min for 3 minutes, then store for later use.

[0133] Comparative Example 7

[0134] This comparative example is a negative electrode enhancement composition, comprising component A and component B. The mass ratio of component A to component B is 5:10.

[0135] The raw materials for preparing component A include asphalt powder, PVA1788, PVA2488, and redispersible polymer powder in a mass ratio of 60:5:30:5. The particle size of the asphalt powder is 20.00 μm, the particle size of PVA1788 and PVA2488 is 40.00 μm, and the particle size of the redispersible polymer powder is 60.00 μm. The asphalt powder, PVA1788, PVA2488, and redispersible polymer powder are weighed according to the formula and mixed in a single-cone double-screw mixer at a speed of 60 r / min for 5 min, then stored for later use.

[0136] Component B comprises a calcium chloride aqueous solution and water in a mass ratio of 60:40. The calcium chloride aqueous solution has a mass concentration of 50%. Weigh the calcium chloride aqueous solution and water according to the formula and mix them in a general-purpose liquid mixer with an acid-resistant pH value ≥1 at a speed of 60 r / min for 3 minutes, then store for later use.

[0137] Comparative Example 8

[0138] This comparative example is a negative electrode enhancement composition, comprising component A and component B. The mass ratio of component A to component B is 5:10.

[0139] The raw materials for preparing component A include asphalt powder, PVA1788, PVA2488, and redispersible polymer powder in a mass ratio of 60:5:30:5. The particle size of the asphalt powder is 20.00 μm, the particle size of PVA1788 and PVA2488 is 40.00 μm, and the particle size of the redispersible polymer powder is 60.00 μm. The asphalt powder, PVA1788, PVA2488, and redispersible polymer powder are weighed according to the formula and mixed in a single-cone double-screw mixer at a speed of 60 r / min for 5 min, then stored for later use.

[0140] Component B consists of hydrochloric acid and water in a mass ratio of 10:40. The molar concentration of hydrochloric acid is 0.20 mol / L. Weigh out the hydrochloric acid and water according to the formula and mix them in a general-purpose liquid mixer with an acid resistance pH value ≥1 at a speed of 60 r / min for 3 minutes, then store for later use.

[0141] Comparative Example 9

[0142] This comparative example is a negative electrode reinforcing composition comprising asphalt powder, PVA1788, PVA2488, redispersible polymer powder, calcium chloride aqueous solution, hydrochloric acid, and water in a mass ratio of 60:5:30:5:120:20:80. The particle size of the asphalt powder is 20.00 μm, the particle size of PVA1788 and PVA2488 is 40.00 μm, the particle size of the redispersible polymer powder is 60.00 μm, the mass concentration of the calcium chloride aqueous solution is 50%, and the molar concentration of the hydrochloric acid is 0.20 mol / L. The asphalt powder, PVA1788, PVA2488, redispersible polymer powder, calcium chloride aqueous solution, hydrochloric acid, and water were weighed according to the formulation and mixed in a single-cone double-screw mixer at a speed of 60 r / min for 10 min, then stored for later use.

[0143] The compositions of Examples 1 to 10 and Comparative Examples 1 to 9 were applied to artificial graphite, respectively. The application of the compositions of Examples 1 to 10 and Comparative Examples 1 to 8 can be referred to the following steps.

[0144] (i) According to the mass ratio of each component set in Examples 1 to 10 and Comparative Examples 1 to 8, component A and carbon micro powder (D50 particle size of 20 μm) were mixed in a ribbon mixer at a stirring speed of 100 r / min for 10 min. Then, component B of Examples 1 to 10 and Comparative Examples 1 to 8 (mass ratio of component B to carbon micro powder of 10:100) was sprayed at a speed of 5.0 kg / min. After mixing at a speed of 200 r / min for 5 min, the material was sent to a buffer chamber for curing and buffering. The pressure in the buffer chamber was -30.0 Pa and the buffering time was 15 min. The curing material was sent to a briquetting machine for briquetting at 4.5 MPa to obtain carbon particles with a particle size of 25 mm.

[0145] (II) The carbon particles are dried, carbonized, and graphitized sequentially using an integrated drying-carbonization-graphitization machine. They are baked at 250℃ until the moisture content is 4.5 wt.%, then pre-carbonized at 1000℃ for 36 hours in a non-oxidizing atmosphere. Graphitization then takes place in a vertical continuous graphitization furnace at 3000℃ for 12 hours in a non-oxidizing atmosphere. The vertical continuous graphitization furnace has a power of 560 kW. The carbon particles move downwards by their own weight within the furnace. The furnace is heated by resistance heating and includes an exhaust system connected to the furnace's interior. The differential pressure at the graphitization flue gas outlet is set to 0 Pa to 10 Pa. After graphitization, the material is dispersed and graded.

[0146] The application of the negative electrode enhancement composition of Comparative Example 9 can be referenced in the following steps.

[0147] (a) The negative electrode enhancement composition of Comparative Example 9 and carbon micro powder with a particle size of 20 μm of D50 were weighed at a mass ratio of 15.6:100 and mixed in a ribbon mixer. The mixing speed was 100 r / min. After mixing for 15 min, the material was sent to a buffer silo for curing and buffering. The pressure in the buffer silo was -30.0 Pa and the buffering time was 15 min. The curing material was sent to a briquetting machine to briquette carbon particles with a particle size of 25 mm.

[0148] (II) The carbon particles are dried, carbonized, and graphitized sequentially using an integrated drying-carbonization-graphitization machine. They are baked at 250℃ until the moisture content is 4.5 wt.%, then pre-carbonized at 1000℃ for 36 hours in a non-oxidizing atmosphere. Graphitization then takes place in a vertical continuous graphitization furnace at 3000℃ for 12 hours in a non-oxidizing atmosphere. The vertical continuous graphitization furnace has a power of 560 kW. The carbon particles move downwards by their own weight within the furnace. The furnace is heated by resistance heating and includes an exhaust system connected to the furnace's interior. The differential pressure at the graphitization flue gas outlet is set to 0 Pa to 10 Pa. After graphitization, the material is dispersed and graded.

[0149] During the application of artificial graphite, it was found that in Comparative Examples 1 and 2, the corn starch and cassava flour lost their binding properties after carbonization, resulting in granular fragmentation that prevented them from entering the vertical graphitization furnace for heat treatment. In Comparative Example 6, the composition failed to provide adequate initial strength to the pressed carbon microparticles, hindering the proper drying process and thus preventing successful application. In Comparative Example 9, the PVA2488 was poorly soluble in water, forming clumps, and the asphalt powder was hydrophobic, resulting in numerous air bubbles in the mixture and uneven mixing, rendering it unsuitable for application.

[0150] The artificial graphite prepared in Examples 1 to 3 was subjected to SEM analysis, and the results are shown in Figures 1 to 3, respectively. The artificial graphite prepared in Comparative Example 5 was difficult to break up due to agglomeration. After being pulverized and ground, it was subjected to SEM analysis, and the results are shown in Figure 4. As can be seen from Figures 1 to 4, the artificial graphite obtained using the composition of this application has a smooth appearance, while the artificial graphite obtained in Comparative Example 5 using the high PVA composition has a rough appearance. This is due to the pulverization and grinding process.

[0151] The initial, dried, carbonized, and graphitized free-fall fracture strength values ​​of carbon particles were measured during the application of the compositions of Examples 1 to 10 and Comparative Examples 1 to 9 to artificial graphite. The results are shown in Table 2. The tap density and powder loss rate of the manufactured artificial graphite products were tested and calculated. The content of elemental metals and compound impurities in the carbon particles was tested, and the coking and caking conditions in the graphitization furnace were recorded. The results are shown in Table 3.

[0152] Table 2. Free-fall fracture resistance values ​​of the compositions of Examples 1 to 10 and Comparative Examples 1 to 9 at various stages of application.

[0153] Table 3 shows the properties of the artificial graphite obtained from the compositions of Examples 1 to 10 and Comparative Examples 1 to 9.

[0154] * indicates that fine powder was produced by crushing and grinding.

[0155] The results in Tables 2 and 3 show that using asphalt powder, polyvinyl alcohol powder, redispersible polymer powder, and phenolic resin powder in a mass ratio of 10–90:10–90:0–10:0–40 as component A, and an aqueous solution containing calcium chloride and hydrochloric acid as component B, the combined effect of components A and B in the artificial graphite process results in a good strength curve. This avoids the loss of powder due to low strength and the need for subsequent grinding and crushing due to excessive strength, leading to a rough surface, reduced tap density, and poor product quality in the final product. Furthermore, using component B, which contains hydrochloric acid and calcium chloride, can reduce the content of high-melting-point and high-volatility-point metallic elements and compounds in the carbon particles, thus preventing the accumulation and caking of these impurities in the graphitization furnace.

[0156] While Comparative Examples 3 to 5 and Comparative Examples 7 to 8 can be used normally to prepare anode materials, Comparative Examples 3 and 4, which use starch-bonded PVA solutions, experience a significant decrease in strength after graphitization, failing to obtain complete graphitized particles and exhibiting a high powder loss rate. In Comparative Example 5, the excessive PVA content results in excessively strong graphitized particles, necessitating crushing and grinding. Furthermore, the reduced degree of graphitization leads to a lower initial efficiency. Component B in Comparative Example 7 lacks hydrochloric acid, resulting in a high impurity content in the obtained anode material. Component B in Comparative Example 8 lacks calcium chloride, making it difficult to form blends with lower melting points from high-melting-point impurities such as SiO2 and CaSiO4 in the carbon micropowder, thus resulting in coking and caking. Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit the scope of protection of this application. Although this application has been described in detail with reference to preferred embodiments, it is not limited to those listed in the embodiments. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the essence and scope of the technical solutions of this application.

Claims

1. A negative electrode-enhancing composition characterized by comprising: The component A includes raw materials of pitch powder, polyvinyl alcohol powder, redispersible rubber powder and phenolic resin powder in a mass ratio of 10-90:10-90:0-10:0-40, and the component B includes an aqueous solution containing calcium chloride and hydrochloric acid, and the mass ratio of the component A to the component B is 1-8:7-28.

2. The negative reinforcement composition of claim 1, wherein, The polyvinyl alcohol powder at least includes at least one of the following characteristics (1) to (3): (1) including two polyvinyl alcohol powders with different polymerization degrees; (2) including polyvinyl alcohol powder PVA1788; (3) including polyvinyl alcohol powder PVA2488.

3. The negative reinforcement composition of claim 1, wherein, At least one of the following characteristics ① to ④ is included: ① the particle size of the pitch powder is 0.01 μm to 80.00 μm; ② the particle size of the polyvinyl alcohol powder is 0.01 μm to 100.00 μm; ③ the particle size of the redispersible rubber powder is 0.01 μm to 80.00 μm; ④ the particle size of the phenolic resin powder is 0.01 μm to 80.00 μm.

4. The negative reinforcement composition of claim 1, wherein, The raw materials of the component B include an aqueous solution of calcium chloride, hydrochloric acid and water in a mass ratio of 20-60:1-20:40-80.

5. The negative reinforcement composition of claim 5, wherein, The mass concentration of the aqueous solution of calcium chloride is 2% to 50%, and the molar concentration of the hydrochloric acid is 0.01 mol / L to 5.00 mol / L.

6. The method of making a negative electrode enhancement composition according to any one of claims 1 to 6, wherein, It includes: (1) each substance in the component A is weighed according to the formula amount, mixed uniformly in a first mixer, stored and used; (2) each substance in the component B is weighed according to the formula amount, mixed uniformly in a second mixer, stored and used.

7. Use of the negative electrode enhancing composition according to any one of claims 1 to 6 or the negative electrode enhancing composition produced by the production method of the negative electrode enhancing composition according to claim 7 in the production of artificial graphite, characterized in that, The negative electrode reinforcing composition and carbon micro powder are mixed and pressed into carbon particles.

8. The use according to claim 8, characterized in that The mass ratio of the negative electrode reinforcing composition to the carbon micro powder is 5-35:50-100.

9. Use according to claim 8, characterized in that, The carbon micro powder is first mixed with the component A, then the component B is added by spraying for mixing, and the carbon particles are pressed, the carbon particles are sequentially dried, baked, carbonized and graphitized to obtain artificial graphite.

10. The use according to claim 10, characterized in that, The initial free-fall anti-crushing strength value of the carbon particles is 300 mm to 800 mm, the free-fall anti-crushing strength value after the drying and baking is 400 mm to 1300 mm, the free-fall anti-crushing strength value after the carbonization is 350 mm to 700 mm, and the free-fall anti-crushing strength value after the graphitization is 150 mm to 450 mm.

Images