A method for producing battery-grade titanium dioxide

Abstract

This invention discloses a method for preparing battery-grade titanium dioxide, comprising: preparation of high-purity titanium solution, low-temperature ice-water controlled-rate hydrolysis, deep impurity removal, hydrothermal crystallization, washing and drying, atmosphere calcination, pulverization and classification, and modification with a composite ball milling slurry. The ball milling slurry is composed of preheated sheet graphene, lanthanum oxide, sodium silicate solution, nano-silicon carbide, mica powder, and sodium lignosulfonate solution in a specific ratio; efficient modification is achieved after ball milling. This invention's method, through an integrated process of low-temperature precise hydrolysis, deep impurity removal, hydrothermal crystallization, atmosphere calcination, and composite ball milling modification of sheet graphene-lanthanum oxide-nano-silicon carbide-mica powder, achieves controllable preparation of high-purity, low-magnetic, nano-sized, highly conductive, and highly stable battery-grade titanium dioxide, fully meeting the requirements for high-end power batteries and energy storage batteries.

Description

Technical Field

[0001] This invention relates to the field of titanium dioxide technology, and more specifically to a method for preparing battery-grade titanium dioxide. Background Technology

[0002] Titanium dioxide possesses advantages such as structural stability, a suitable lithium intercalation platform, long cycle life, low cost, and environmental friendliness, making it a core anode material and functional dopant for long-range, high-safety, and long-life battery systems. Battery-grade titanium dioxide has extremely high requirements for purity, magnetic impurities, particle size distribution, crystal phase purity, conductivity, dispersibility, and interfacial stability: Main content ≥99.5wt%, total heavy metals and magnetic impurities <0.2ppm, to avoid battery self-discharge, micro-short circuits, and safety hazards; nanoscale particle size, narrow distribution, and no agglomeration, ensuring ion transport efficiency and electrochemical consistency; pure anatase crystal phase with high crystallinity and no impurities, ensuring stable charge-discharge structure; excellent conductivity, solving the problems of low rate capability and large polarization caused by the low intrinsic conductivity of titanium dioxide; good interfacial compatibility, suppressing side reactions and improving initial coulombic efficiency and cycle life. Existing technologies have significant drawbacks: industrial titanium dioxide has high impurities, excessive magnetic foreign matter, and large particle size, making it unsuitable for direct use in batteries; ordinary sol-gel and hydrothermal methods cannot simultaneously achieve high purity, low magnetic properties, narrow distribution, and high conductivity; there is a lack of efficient composite modification systems, resulting in poor conductivity and limited rate performance of titanium dioxide; nanoparticles are prone to agglomeration, have poor dispersibility, and experience rapid degradation of electrochemical performance; the processes are complex, costly, and difficult to scale up industrially, making it difficult to meet the large-scale demands of the battery industry.

[0003] Therefore, this invention provides a method for preparing battery-grade titanium dioxide modified by composite ball milling fluid. Through an integrated process of low-temperature precise hydrolysis, deep impurity removal, hydrothermal crystallization, atmosphere calcination, and composite ball milling modification of sheet graphene-lanthanum oxide-nano silicon carbide-mica powder, high-purity, low-magnetic, nano-conductive, and highly stable battery-grade titanium dioxide can be controllably prepared, fully meeting the requirements of high-end power batteries and energy storage batteries. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the purpose of this invention is to provide a method for preparing battery-grade titanium dioxide to solve the problems mentioned in the background art.

[0005] The present invention solves the technical problem by adopting the following technical solution: This invention provides a method for preparing battery-grade titanium dioxide, comprising the following steps: S1, Preparation and pretreatment of high-purity titanium solution; S2, low-temperature rate-controlled hydrolysis to generate hydrated titanium dioxide precursor; S3, deep impurity removal to remove heavy metals and magnetic foreign matter; S4, hydrothermal crystallization regulates particle size and crystallinity; S5, washing, dehydration, and drying; S6, calcination in an atmosphere to control the crystal phase; S7, pulverization and classification to obtain titanium dioxide primary; S8, ball milling improvement treatment of titanium dioxide primary with ball milling slurry to obtain battery-grade titanium dioxide.

[0006] Preferably, the ball milling improvement treatment in S8 is as follows: 25-30% of the total amount of ball milling fluid is added to the titanium dioxide precursor, the ball milling speed is 1000-1500 r / min, the ball milling is carried out for 2 hours, and the mixture is filtered and dried to obtain battery-grade titanium dioxide; The ball milling fluid is prepared according to the following steps: S1a: Preheat sheet graphene at 55-60℃ for 1 hour, then mix 3-5 parts of preheated graphene, 2-4 parts of lanthanum oxide, and 5-8 parts of sodium silicate solution with a mass fraction of 2-5% evenly to obtain graphene liquid. S1b: Mix 2-4 parts of nano-silicon carbide, 1-3 parts of mica powder, and 5-8 parts of sodium lignosulfonate solution with a mass fraction of 10-15% to obtain an additive solution; stir the additive solution and graphene solution at a weight ratio of 3:(5-7) to obtain a ball milling slurry.

[0007] Preferably, the titanium source in S1 is tetrabutyl titanate or high-purity titanium tetrachloride; the concentration of the titanium solution is 0.6-1.0 mol / L, and one or more of hydrogen peroxide, nitric acid or citric acid are added as stabilizers.

[0008] Preferably, the hydrolysis temperature in S2 is an ice-water system of 0-10℃, the pH adjuster is sodium carbonate and sodium bicarbonate strong base weak acid salt, the pH is adjusted to 6.8-8.0, and the hydrolysis time is 1.5-3h.

[0009] Preferably, the deep impurity removal in S3 includes at least two steps of oxidation to remove iron, solvent extraction, ultrafiltration, and high-intensity magnetic filtration; the magnetic field strength of the magnetic filtration is ≥12000Gs.

[0010] Preferably, the hydrothermal crystallization temperature in S4 is 160-220℃, and the time is 2-6h; one or more of sodium polyacrylate and PVP are added to the system as dispersants.

[0011] Preferably, in step S5, ultrapure water is used for multi-stage countercurrent washing until the conductivity of the washing liquid is ≤5μS / cm and the chloride ion concentration is ≤5ppm; the drying method is vacuum drying or spray drying.

[0012] Preferably, the calcination in S6 is carried out in an air atmosphere, with a heating rate of 2-5℃ / min, a calcination temperature of 400-600℃, and a time of 2-4h, resulting in a pure anatase phase product.

[0013] Preferably, in S7, air jet milling or supersonic air jet milling is used, combined with high-precision classification, to obtain powder with a particle size D50=20-100nm and a particle size distribution range ≤1.5.

[0014] Preferably, the preparation of battery-grade titanium dioxide satisfies: TiO Content ≥99.5wt%, total amount of magnetic foreign matter (Fe+Cr+Ni+Zn) <0.2ppm, specific surface area 50-150m² / g, can be used as a negative electrode material for lithium-ion batteries, sodium-ion batteries, or as a precursor for lithium titanate.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention utilizes a composite ball milling fluid to achieve multi-dimensional and multi-effect synergy. Modified sheet-like graphene constructs a continuous two-dimensional conductive network, significantly improving electronic conductivity. Lanthanum oxide acts as a rare-earth doping site, stabilizing the crystal lattice, suppressing phase transitions, and reducing irreversible capacity. Nano-silicon carbide enhances structural strength, improves wear resistance, and increases ion transport capacity. Mica powder provides layered buffering and lubrication, reducing charge-discharge volume expansion. Sodium silicate and sodium lignosulfonate achieve efficient dispersion, prevent agglomeration, and improve interfacial compatibility. High-energy ball milling achieves uniform coating and interfacial strengthening. High-energy ball milling at 1000-1500 r / min ensures uniform nanoscale loading of modified components on the titanium dioxide surface without damaging the crystal structure, forming a stable bonding interface and significantly improving rate performance, cycle life, and high / low temperature adaptability. The resulting product is TiO2. Content ≥99.5wt%, magnetic foreign matter (Fe+Cr+Ni+Zn) <0.2ppm, particle size D50=20-100nm, distribution range ≤1.5, pure anatase phase, specific surface area 50-150m² / g, fully meets the HG / T6294-2024 standard for titanium dioxide for batteries, significantly improves electrochemical performance and conductivity, with an initial coulombic efficiency of ≥88%, a capacity retention rate of ≥88% after 1000 cycles, excellent rate performance, and stable charge and discharge at 1C / 5C / 10C, ​​making it suitable for power and energy storage batteries. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to specific examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] This embodiment describes a method for preparing battery-grade titanium dioxide, comprising the following steps: S1, Preparation and pretreatment of high-purity titanium solution; S2, low-temperature rate-controlled hydrolysis to generate hydrated titanium dioxide precursor; S3, deep impurity removal to remove heavy metals and magnetic foreign matter; S4, hydrothermal crystallization regulates particle size and crystallinity; S5, washing, dehydration, and drying; S6, calcination in an atmosphere to control the crystal phase; S7, pulverization and classification to obtain titanium dioxide primary; S8, ball milling improvement treatment of titanium dioxide primary with ball milling slurry to obtain battery-grade titanium dioxide.

[0018] In S1 of this embodiment, the titanium source is tetrabutyl titanate or high-purity titanium tetrachloride; the concentration of the titanium solution is 0.6-1.0 mol / L, and one or more of hydrogen peroxide, nitric acid or citric acid are added as stabilizers.

[0019] In this embodiment, S2 is a 0-10℃ ice-water system with sodium carbonate and sodium bicarbonate as strong base-weak acid salts to adjust the pH to 6.8-8.0 and a hydrolysis time of 1.5-3 hours.

[0020] In this embodiment, S3 deep impurity removal includes at least two of the following steps: iron removal by oxidation, solvent extraction, ultrafiltration, and high-intensity magnetic filtration; the magnetic field strength of the magnetic filtration is ≥12000Gs.

[0021] In this embodiment, the hydrothermal crystallization temperature in S4 is 160-220℃, and the time is 2-6h; one or more of sodium polyacrylate and PVP are added to the system as dispersants.

[0022] In S5 of this embodiment, ultrapure water is used for multi-stage countercurrent washing until the conductivity of the washing liquid is ≤5μS / cm and the chloride ion concentration is ≤5ppm; the drying method is vacuum drying or spray drying.

[0023] In S6 of this embodiment, calcination is carried out in an air atmosphere, with a heating rate of 2-5℃ / min, a calcination temperature of 400-600℃, and a time of 2-4h. The resulting product is a pure anatase phase.

[0024] In S7 of this embodiment, air jet milling or supersonic air jet milling is used, combined with high-precision classification, to obtain powder with a particle size D50 of 20-100nm and a particle size distribution range of ≤1.5.

[0025] In S8 of this embodiment, the ball milling improvement treatment is as follows: 25-30% of the total amount of ball milling fluid is added to the titanium dioxide precursor, the ball milling speed is 1000-1500 r / min, the ball milling is carried out for 2 hours, and the mixture is filtered and dried to obtain battery-grade titanium dioxide. The ball milling fluid is prepared according to the following steps: S1a: Preheat sheet graphene at 55-60℃ for 1 hour, then mix 3-5 parts of preheated graphene, 2-4 parts of lanthanum oxide, and 5-8 parts of sodium silicate solution with a mass fraction of 2-5% evenly to obtain graphene liquid. S1b: Mix 2-4 parts of nano-silicon carbide, 1-3 parts of mica powder, and 5-8 parts of sodium lignosulfonate solution with a mass fraction of 10-15% to obtain an additive solution; stir the additive solution and graphene solution at a weight ratio of 3:(5-7) to obtain a ball milling slurry.

[0026] The battery-grade titanium dioxide prepared in this embodiment satisfies: TiO Content ≥99.5wt%, total amount of magnetic foreign matter (Fe+Cr+Ni+Zn) <0.2ppm, specific surface area 50-150m² / g, can be used as a negative electrode material for lithium-ion batteries, sodium-ion batteries, or as a precursor for lithium titanate.

[0027] Example 1 This embodiment describes a method for preparing battery-grade titanium dioxide, comprising the following steps: S1, Preparation and pretreatment of high-purity titanium solution; S2, low-temperature rate-controlled hydrolysis to generate hydrated titanium dioxide precursor; S3, deep impurity removal to remove heavy metals and magnetic foreign matter; S4, hydrothermal crystallization regulates particle size and crystallinity; S5, washing, dehydration, and drying; S6, calcination in an atmosphere to control the crystal phase; S7, pulverization and classification to obtain titanium dioxide primary; S8, ball milling improvement treatment of titanium dioxide primary with ball milling slurry to obtain battery-grade titanium dioxide.

[0028] In S1 of this embodiment, the titanium source is tetrabutyl titanate or high-purity titanium tetrachloride; the concentration of the titanium liquid is 0.8 mol / L, and hydrogen peroxide is added as a stabilizer.

[0029] In this embodiment, S2 is a 5°C ice-water system with sodium carbonate as the pH adjuster, adjusted to pH 7.2, and hydrolysis time of 2 hours.

[0030] In this embodiment, S3 deep impurity removal includes iron removal by oxidation, solvent extraction, ultrafiltration, and high-intensity magnetic filtration; the magnetic field strength of the magnetic filtration is ≥12000Gs.

[0031] In this embodiment, the hydrothermal crystallization temperature in S4 is 180°C, and the time is 3 hours; sodium polyacrylate is added to the system as a dispersant.

[0032] In S5 of this embodiment, ultrapure water is used for multi-stage countercurrent washing until the conductivity of the washing liquid is ≤5μS / cm and the chloride ion concentration is ≤5ppm; the drying method is vacuum drying or spray drying.

[0033] In S6 of this embodiment, calcination is carried out in an air atmosphere, with a heating rate of 3.5℃ / min, a calcination temperature of 500℃, and a time of 3h. The resulting product is a pure anatase phase.

[0034] In S7 of this embodiment, air jet milling or supersonic air jet milling is used, combined with high-precision classification, to obtain powder with a particle size D50=50nm and a particle size distribution span ≤1.5.

[0035] In S8 of this embodiment, the ball milling improvement treatment is as follows: 27.5% of the total amount of ball milling fluid is added to the titanium dioxide precursor, the ball milling speed is 1250 r / min, the ball milling is carried out for 2 hours, and the mixture is filtered and dried to obtain battery-grade titanium dioxide. The ball milling fluid is prepared according to the following steps: S1a: Preheat sheet graphene at 58℃ for 1 hour, then mix 4 parts of preheated graphene, 3 parts of lanthanum oxide, and 6.5 parts of sodium silicate solution with a mass fraction of 3.5% to obtain graphene liquid. S1b: Mix 3 parts of nano-silicon carbide, 2 parts of mica powder, and 6.5 parts of sodium lignosulfonate solution with a mass fraction of 12.5% ​​to obtain an additive solution; mix the additive solution and graphene solution with a weight ratio of 3:6 to obtain a ball milling slurry.

[0036] The battery-grade titanium dioxide prepared in this embodiment satisfies: TiO Content ≥99.5wt%, total amount of magnetic foreign matter (Fe+Cr+Ni+Zn) <0.2ppm, specific surface area 100m² / g, can be used as a negative electrode material for lithium-ion batteries, sodium-ion batteries, or as a precursor for lithium titanate.

[0037] Example 2 This embodiment describes a method for preparing battery-grade titanium dioxide, comprising the following steps: S1, Preparation and pretreatment of high-purity titanium solution; S2, low-temperature rate-controlled hydrolysis to generate hydrated titanium dioxide precursor; S3, deep impurity removal to remove heavy metals and magnetic foreign matter; S4, hydrothermal crystallization regulates particle size and crystallinity; S5, washing, dehydration, and drying; S6, calcination in an atmosphere to control the crystal phase; S7, pulverization and classification to obtain titanium dioxide primary; S8, ball milling improvement treatment of titanium dioxide primary with ball milling slurry to obtain battery-grade titanium dioxide.

[0038] In S1 of this embodiment, the titanium source is tetrabutyl titanate or high-purity titanium tetrachloride; the concentration of the titanium solution is 0.6 mol / L, and nitric acid is added as a stabilizer.

[0039] In this embodiment, S2 is a 0°C ice-water system with sodium bicarbonate as the pH adjuster, adjusted to pH 6.8, and hydrolysis time 1.5 h.

[0040] In this embodiment, S3 deep impurity removal includes iron removal by oxidation, solvent extraction, ultrafiltration, and high-intensity magnetic filtration; the magnetic field strength of the magnetic filtration is ≥12000Gs.

[0041] In this embodiment, the hydrothermal crystallization temperature in S4 is 160°C, and the time is 2 hours; PVP is added to the system as a dispersant.

[0042] In S5 of this embodiment, ultrapure water is used for multi-stage countercurrent washing until the conductivity of the washing liquid is ≤5μS / cm and the chloride ion concentration is ≤5ppm; the drying method is vacuum drying or spray drying.

[0043] In S6 of this embodiment, calcination is carried out in an air atmosphere, with a heating rate of 2℃ / min, a calcination temperature of 400℃, and a time of 2h. The resulting product is a pure anatase phase.

[0044] In S7 of this embodiment, airflow milling or supersonic airflow milling is used, combined with high-precision classification, to obtain powder with a particle size D50=20nm and a particle size distribution span ≤1.5.

[0045] In S8 of this embodiment, the ball milling improvement process is as follows: 25% of the total amount of ball milling fluid is added to the titanium dioxide precursor, the ball milling speed is 1000 r / min, the ball milling is carried out for 2 hours, and the mixture is filtered and dried to obtain battery-grade titanium dioxide. The ball milling fluid is prepared according to the following steps: S1a: Preheat sheet graphene at 55℃ for 1 hour, then mix 3 parts of preheated graphene, 2 parts of lanthanum oxide, and 5 parts of sodium silicate solution with a mass fraction of 2% evenly to obtain graphene liquid. S1b: Mix 2 parts of nano-silicon carbide, 1 part of mica powder, and 5 parts of sodium lignosulfonate solution with a mass fraction of 10% to obtain an additive solution; stir the additive solution and graphene solution at a weight ratio of 35 to obtain a ball milling slurry.

[0046] The battery-grade titanium dioxide prepared in this embodiment satisfies: TiO Content ≥99.5wt%, total amount of magnetic foreign matter (Fe+Cr+Ni+Zn) <0.2ppm, specific surface area 50m² / g, can be used as a negative electrode material for lithium-ion batteries, sodium-ion batteries, or as a precursor for lithium titanate.

[0047] Example 3 This embodiment describes a method for preparing battery-grade titanium dioxide, comprising the following steps: S1, Preparation and pretreatment of high-purity titanium solution; S2, low-temperature rate-controlled hydrolysis to generate hydrated titanium dioxide precursor; S3, deep impurity removal to remove heavy metals and magnetic foreign matter; S4, hydrothermal crystallization regulates particle size and crystallinity; S5, washing, dehydration, and drying; S6, calcination in an atmosphere to control the crystal phase; S7, pulverization and classification to obtain titanium dioxide primary; S8, ball milling improvement treatment of titanium dioxide primary with ball milling slurry to obtain battery-grade titanium dioxide.

[0048] In S1 of this embodiment, the titanium source is tetrabutyl titanate or high-purity titanium tetrachloride; the concentration of the titanium solution is 1.0 mol / L, and citric acid is added as a stabilizer.

[0049] In this embodiment, S2 is a 10°C ice-water system with sodium carbonate as the pH adjuster, adjusted to pH 8.0, and hydrolysis time of 3 hours.

[0050] In this embodiment, S3 deep impurity removal includes iron removal by oxidation, solvent extraction, ultrafiltration, and high-intensity magnetic filtration; the magnetic field strength of the magnetic filtration is ≥12000Gs.

[0051] In this embodiment, the hydrothermal crystallization temperature in S4 is 220°C, and the time is 6 hours; PVP is added to the system as a dispersant.

[0052] In S5 of this embodiment, ultrapure water is used for multi-stage countercurrent washing until the conductivity of the washing liquid is ≤5μS / cm and the chloride ion concentration is ≤5ppm; the drying method is vacuum drying or spray drying.

[0053] In S6 of this embodiment, calcination is carried out in an air atmosphere, with a heating rate of 5°C / min, a calcination temperature of 600°C, and a time of 4 hours. The resulting product is a pure anatase phase.

[0054] In S7 of this embodiment, airflow milling or supersonic airflow milling is used, combined with high-precision classification, to obtain powder with a particle size D50=100nm and a particle size distribution span ≤1.5.

[0055] In S8 of this embodiment, the ball milling improvement process is as follows: 30% of the total amount of ball milling liquid is added to the titanium dioxide precursor, the ball milling speed is 1500 r / min, the ball milling is carried out for 2 hours, and the mixture is filtered and dried to obtain battery-grade titanium dioxide. The ball milling fluid is prepared according to the following steps: S1a: Preheat sheet graphene at 60℃ for 1 hour, then mix 5 parts of preheated graphene, 4 parts of lanthanum oxide, and 8 parts of sodium silicate solution with a mass fraction of 5% to obtain graphene liquid. S1b: Mix 4 parts of nano-silicon carbide, 3 parts of mica powder, and 8 parts of sodium lignosulfonate solution with a mass fraction of 15% to obtain an additive solution; stir the additive solution and graphene solution at a weight ratio of 3:7 to obtain a ball milling slurry.

[0056] The battery-grade titanium dioxide prepared in this embodiment satisfies: TiO With a content ≥99.5wt%, total magnetic foreign matter (Fe+Cr+Ni+Zn) <0.2ppm, and a specific surface area of ​​150m² / g, it can be used as a negative electrode material for lithium-ion batteries, sodium-ion batteries, or lithium titanate precursors.

[0057] Scale settings Comparative Example 1: No ball milling fluid modification treatment was performed; all other aspects were the same as in Example 1. Comparative Example 2: No sheet graphene was added to the ball milling slurry; all other aspects were the same as in Example 1. Comparative Example 3: Lanthanum oxide was not added to the ball milling slurry; all other aspects were the same as in Example 1. Comparative Example 4: No nano-silicon carbide was added to the ball milling slurry; otherwise, it was the same as in Example 1. Comparative Example 5: No mica powder was added to the ball milling fluid; otherwise, it was the same as in Example 1. Comparative Example 6: Deionized water was used instead of the ball milling fluid, and the rest was the same as in Example 1; Comparative Example 7: Industrial titanium dioxide was used directly, without the process of this invention.

[0058] Performance testing According to HG / T6294-2024, ICP-OES, laser particle size analysis, BET, XRD, resistivity, and electrochemical half-cell testing, Table 1 compares the physicochemical properties.

[0059] The results are as follows: Table 2 Comparison of Electrochemical Performance Performance test results analysis The resistivity of the conductive examples was 126-182 Ω·cm, which was significantly improved compared to Comparative Example 1. Comparative Example 2 showed a sharp increase in resistivity due to the lack of graphene, proving that sheet-like graphene is the core of constructing the conductive network.

[0060] Particle size and dispersibility analysis: Example 1 showed controllable particle size, narrow distribution, and no agglomeration; Comparative Example 6 showed obvious agglomeration due to the use of ordinary water milling, and Comparative Example 7 showed large particle size, proving that the low-temperature hydrolysis + hydrothermal + composite ball milling fluid of the present invention can achieve high nano-dispersion.

[0061] Comparative Example 7 showed excessive levels of impurities and magnetic foreign matter, rendering it unusable for batteries, demonstrating that deep impurity removal and magnetic filtration are essential processes for battery-grade applications.

[0062] The initial coulombic efficiency analysis of the example showed an initial efficiency of ≥87.9%, which was much higher than that of the comparative example. This was because ball milling modification formed a stable interfacial film, and lanthanum oxide reduced surface defects and side reactions.

[0063] Rate and Cycling Performance Analysis: Example 1C exhibits high capacity and excellent retention after 1000 cycles, while the comparative examples all show significant capacity decay. This is due to the synergistic effect of graphene enhancing conductivity, lanthanum oxide stabilizing the lattice, nano-silicon carbide reinforcing the structure, and mica powder buffering expansion, all contributing to a long lifespan.

[0064] The comparative results show that ball milling fluid modification, sheet graphene, lanthanum oxide, nano-silicon carbide, and mica powder are all essential technical features. The absence of any one of these components will lead to a significant decrease in conductivity, dispersibility, and cycle stability, proving that this invention has outstanding inventiveness and practicality.

[0065] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0066] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing battery-grade titanium dioxide, characterized in that, Includes the following steps: S1, Preparation and pretreatment of high-purity titanium solution; S2, low-temperature rate-controlled hydrolysis to generate hydrated titanium dioxide precursor; S3, deep impurity removal to remove heavy metals and magnetic foreign matter; S4, hydrothermal crystallization regulates particle size and crystallinity; S5, washing, dehydration, and drying; S6, calcination in an atmosphere to control the crystal phase; S7, pulverization and classification to obtain titanium dioxide primary; S8, ball milling improvement treatment of titanium dioxide primary with ball milling slurry to obtain battery-grade titanium dioxide.

2. The preparation method according to claim 1, characterized in that, The ball milling improvement process is as follows: add 25-30% of the total amount of ball milling fluid to the titanium dioxide precursor, mill at a speed of 1000-1500 r / min for 2 hours, filter and dry to obtain battery-grade titanium dioxide; The ball milling fluid is prepared according to the following steps: S1a: Preheat sheet graphene at 55-60℃ for 1 hour, then mix 3-5 parts of preheated graphene, 2-4 parts of lanthanum oxide, and 5-8 parts of sodium silicate solution with a mass fraction of 2-5% evenly to obtain graphene liquid. S1b: Mix 2-4 parts of nano-silicon carbide, 1-3 parts of mica powder, and 5-8 parts of sodium lignosulfonate solution with a mass fraction of 10-15% to obtain an additive solution; stir the additive solution and graphene solution at a weight ratio of 3:(5-7) to obtain a ball milling slurry.

3. The preparation method according to claim 1, characterized in that, In S1, the titanium source is tetrabutyl titanate or high-purity titanium tetrachloride; the concentration of the titanium solution is 0.6-1.0 mol / L, and one or more of hydrogen peroxide, nitric acid or citric acid are added as stabilizers.

4. The preparation method according to claim 1, characterized in that, S2 is a 0-10℃ ice-water system with sodium carbonate and sodium bicarbonate as strong base-weak acid salts to adjust the pH to 6.8-8.0 and a hydrolysis time of 1.5-3 hours.

5. The preparation method according to claim 1, characterized in that, S3 deep impurity removal includes at least two of the following steps: iron removal by oxidation, solvent extraction, ultrafiltration, and high-intensity magnetic filtration; the magnetic field strength of the magnetic filtration is ≥12000Gs.

6. The preparation method according to claim 1, characterized in that, The hydrothermal crystallization temperature in S4 is 160-220℃, and the time is 2-6h; one or more of sodium polyacrylate and PVP are added to the system as dispersants.

7. The preparation method according to claim 1, characterized in that, S5 uses multi-stage countercurrent washing with ultrapure water until the conductivity of the washing solution is ≤5μS / cm and the chloride ion concentration is ≤5ppm; the drying method is vacuum drying or spray drying.

8. The preparation method according to claim 1, characterized in that, In S6, calcination is carried out in an air atmosphere with a heating rate of 2-5℃ / min, a calcination temperature of 400-600℃, and a time of 2-4h. The resulting product is pure anatase phase.

9. The preparation method according to claim 1, characterized in that, The S7 uses air jet milling or supersonic air jet milling, combined with high-precision classification, to obtain powder with a particle size D50 of 20-100nm and a particle size distribution range of ≤1.

5.

10. The preparation method according to any one of claims 1-9, characterized in that, The prepared battery-grade titanium dioxide satisfies: TiO Content ≥99.5wt%, total amount of magnetic foreign matter (Fe+Cr+Ni+Zn) <0.2ppm, specific surface area 50-150m² / g, can be used as a negative electrode material for lithium-ion batteries, sodium-ion batteries, or as a precursor for lithium titanate.

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