A low-sulfur and low-tap density ternary precursor small particle and preparation method thereof

Abstract

The present invention belongs to the technical field of material chemistry, and particularly relates to a low-sulfur and low-tap-density ternary precursor small particle and a preparation method thereof. The production process of the ternary precursor is optimized in the present invention. By controlling the pH value, ammonia concentration and alkali concentration during the reaction, physical and chemical adsorption of S element can be reduced during the reaction, and the tap density can be decreased, so that the sulfur content in the small particle product of the ternary precursor is reduced to below 700 ppm, and the tap density of the product is reduced to below 1.35 g / cm<supgt;3< / supgt;. Compared with other methods, the product of the present invention has the advantage of low production cost, reduces the dosage of dilute alkali during the reaction, and simultaneously reduces the number of alkali washing and water washing times. The low-sulfur and low-tap-density ternary precursor small particle product produced by the present invention has wide applicability, no obvious fine powder on the electron microscope surface, and does not affect the physical and chemical properties for subsequent use of the ternary precursor, and can be widely applied in production.

Description

Technical Field

[0001] The invention belongs to the technical field of material chemistry, and in particular relates to a low-sulfur and low-tap density ternary precursor small particle and a preparation method thereof. Background Art

[0002] In recent years, layered Ni-Co-Mn ternary composite materials have been widely used in electric vehicles, energy storage batteries and other fields due to their high specific capacity, low cost, long cycle life and high energy density. As an important raw material for preparing lithium-ion batteries, nickel-cobalt-manganese ternary precursor materials largely determine the quality of their final performance. Since the ternary precursor material is prepared by coprecipitation of three sulfates during the preparation process, a large amount of sulfate ions are attached to the inside and surface of the material. Although it is washed many times with dilute alkali and hot water, the S inside the material is always difficult to wash away, resulting in the S content in the products produced by this process generally exceeding the standard. This not only increases the washing cost, but also has a great impact on the performance of the final battery. In addition, due to the different requirements of downstream customers for battery doping, the demand for low-sulfur and low-tap density ternary precursors has gradually increased. The existing technology is mainly aimed at preparing low-sulfur and high-tap density ternary precursors, and rarely involves low-sulfur and low-tap density ternary precursors. Summary of the invention

[0003] In view of the problems existing in the prior art, the present invention provides a low-sulfur and low-tap density ternary precursor small particle and a preparation method thereof, which not only provides a simple and feasible production process for reducing sulfur and tap density, but also reduces washing costs and the amount of dilute alkali used during the reaction. More importantly, it reduces the sulfur content in the product and reduces the tap density, so that the sulfur content is stably controlled within 700ppm and the tap density is stably controlled within 1.35g / cm 3 The present invention specifically includes the following contents:

[0004] A method for preparing small particles of a low-sulfur and low-tap density ternary precursor comprises the following steps:

[0005] (1) preparing a ternary solution: using nickel sulfate, cobalt sulfate and manganese sulfate as raw materials, preparing a sulfate mixed solution with a total concentration of 100.0-120.0 g / L; the specific total concentration of the sulfate mixed solution can be 105 g / L, 110 g / L, 115 g / L, 118 g / L, etc.;

[0006] (2) preparing a base liquid: introducing nitrogen as a protective gas into a reaction kettle, adding a certain amount of pure water, liquid alkali and ammonia water as a base liquid, and stirring at a certain temperature to mix the base liquid uniformly, controlling the pH value of the base liquid to be 11.30-12.50 (for example, the pH value can be 11.4, 11.5, 11.8, 12.0, 12.25, etc.), the ammonia concentration to be 5.0-12.0 g / L (for example, 5.2 g / L, 5.5 g / L, 6.0 g / L, 6.5 g / L, 7 g / L, 8 g / L, 9 g / L, 10 g / L, 11 g / L, etc.), and the alkali concentration to be 12.0-25.0 g / L (for example, 12.2 g / L, 12.5 g / L, 13 g / L, 14 g / L, 15 g / L, 16 g / L, 20 g / L, 22 g / L, 24 g / L, etc.);

[0007] (3) coprecipitation reaction: adding the sulfate solution prepared in step (1) together with liquid alkali and aqueous ammonia to the reactor described in step (2) at a certain rate to carry out a coprecipitation reaction, controlling the temperature of the reaction system to be 40.0-65.0° C. (e.g., 42° C., 45° C., 50° C., 55° C., 58° C., 60° C., 64° C., etc.), and stirring the reactor at a rate of 150-360 r / min (e.g., 160 r / min, 180 r / min, 200 r / min, 250 r / min, 280 r / min, 300 r / min, 350 r / min, etc.);

[0008] (4) Particle growth: The rate at which the liquid alkali and ammonia water are added to the reactor is adjusted so that the pH value of the reaction system drops to 10.10-11.40 within 4.0-20.0 h (the specific time can be 5 h, 6 h, 8 h, 10 h, 15 h, 18 h, etc., and the pH value can drop to 10.20, 10.50, 10.80, 11.00, 11.30, etc.), while maintaining the ammonia concentration and the alkali concentration at 5.0-12.0 g / L (for example, 6.0 g / L, 7.0 g / L, 8.0 g / L, 9.0 g / L, 10.0 g / L, 11.0 g / L, etc.). / L, etc.) and 13.0-25.0g / L (e.g. 14.0g / L, 15.0g / L, 18.0g / L, 20.0g / L, 22.0g / L, 24.0g / L, etc.), and then stabilize the pH value at 10.10-11.40 (e.g. 10.20, 10.40, 10.50, 10.80, 11.00, 11.20, etc.) until the ternary precursor particles in the reaction system grow to a D50 of 3.3-3.7μm (e.g. 3.4μm, 3.5μm, 3.6μm, 3.65μm, etc.) and then terminate the reaction.

[0009] Preferably, the molar ratio of nickel, cobalt and manganese in the sulfate mixed solution of step (1) is (4-8):(0.5-3):(1-4), for example 8:1:1, 6:2:2, 5:2:3, 7:1:2, etc.

[0010] Preferably, the mass concentration of the liquid caustic soda in step (2) is 25.0%-35.0%.

[0011] Preferably, the mass concentration of the ammonia water in step (2) is 12.0-20.0%.

[0012] Preferably, the temperature in step (2) is 40.0-65.0°C, specifically 42°C, 45°C, 55°C, 58°C, 60°C, 64°C, etc.

[0013] Preferably, the stirring in step (2) adopts a single-layer paddle, and the stirring rate is 150-360r / min, for example, 160r / min, 180r / min, 200r / min, 250r / min, 280r / min, 290r / min, 350r / min, etc.

[0014] Preferably, the method further comprises step (5): washing the slurry obtained in step (4) with hot diluted alkali and pure water for multiple times, preferably twice, and then drying to obtain the low-sulfur and low-tap density ternary precursor small particles.

[0015] Preferably, the mass concentration of the dilute alkali in step (5) is 2.0%-3.5% (for example, 2.1%, 2.5%, 2.8%, 3.0%, 3.2%, 3.4%, etc.), the temperature is 40.0-70.0°C (for example, 42°C, 45°C, 50°C, 55°C, 60°C, 65°C, etc.), and the temperature of the pure water is 40.0-70.0°C (for example, 42°C, 45°C, 50°C, 55°C, 60°C, 65°C, etc.).

[0016] A low-sulfur and low-tap density ternary precursor material prepared by the method described in the invention.

[0017] Beneficial effects of the present invention:

[0018] (1) The present invention provides a novel method for preparing small particles of a ternary precursor with low sulfur content and low tap density by optimizing the production process of the ternary precursor. The process is simple. By controlling the pH value, ammonia concentration and alkali concentration during the reaction, the physical and chemical adsorption of the sulfur element and the tap density can be reduced during the reaction, thereby reducing the sulfur content in the small particles of the ternary precursor product to below 700 ppm, and the tap density of the product is reduced to 1.35 g / cm 3 the following;

[0019] (2) Compared with other methods, the product of the present invention has the advantage of low production cost, reduces the amount of dilute alkali used in the reaction process, and reduces the number of alkali washing and water washing;

[0020] (3) The low-sulfur and low-tap density ternary precursor small particle product produced by the present invention has wide applicability, no obvious micropowder on the electron microscope surface, and does not affect the physical and chemical properties of the ternary precursor in subsequent use, and can be used on a large scale in production. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The process flow chart of the method disclosed in the present invention is shown in FIG. DETAILED DESCRIPTION

[0022] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments shown below do not limit the invention content described in the claims. In addition, the entire contents of the structures represented by the following embodiments are not limited to those necessary as solutions to the invention described in the claims.

[0023] Example 1

[0024] A method for preparing small particles of a low-sulfur and low-tap density ternary precursor comprises the following steps:

[0025] (1) Nickel sulfate, cobalt sulfate and manganese sulfate were prepared in a molar ratio of (5.0:2.0:3.0) to prepare a ternary solution with a total metal concentration of 110.0 g / L, a diluted alkali with a mass concentration of 32.0%, and an ammonia solution with a mass concentration of 15.0%.

[0026] (2) To 6.0m 3 Add 3.0m 3 150.0L of pure water, 150.0L of ammonia water and 42.0L of dilute alkali were introduced into the reactor at a flow rate of 0.5m 3 / h of nitrogen, turn on the single-layer paddle for stirring, set the speed to 200-360r / min, mix the bottom liquid evenly, raise the temperature to 45-60℃ and maintain stable, control the pH value of the bottom liquid at 11.45-12.45, the ammonia concentration at 6.8-10.5g / L, and the alkali concentration at 15.5-24.8g / L.

[0027] (3) After the bottom liquid in the reactor reaches the above conditions, a certain flow rate of ternary liquid, liquid alkali and ammonia water is added to the reactor at the same time by controlling the mass flowmeter. After maintaining the reaction under high pH conditions for 4-8 hours, the pH value is reduced to 10.20-11.30 within 8-20 hours by controlling the flow rate of dilute alkali. At the same time, the ammonia flow rate is controlled to maintain the ammonia concentration and total alkalinity at 5.0-9.5g / L and 15.5-24.8g / L respectively. The reaction is carried out under this condition until the particles grow to a D50 of 3.3-3.7μm and then the feeding is stopped.

[0028] (4) The slurry obtained by the reaction is poured into a filter press and washed twice with 45-55°C dilute alkali and 55-65°C pure water alternately, each washing for 8-15 minutes. After drying, a new type of low-sulfur and low-tap density ternary precursor small particles is obtained. The sulfur content of the material is 647ppm as detected by ICP, and the tap density of the material is 1.30g / cm 3 .

[0029] Example 2

[0030] A method for preparing small particles of a low-sulfur and low-tap density ternary precursor comprises the following steps:

[0031] (1) Nickel sulfate, cobalt sulfate and manganese sulfate were prepared in a molar ratio of (7.0:1.0:2.0) to prepare a ternary solution with a total metal concentration of 108.0 g / L, a diluted alkali with a mass concentration of 30.0%, and an ammonia solution with a mass concentration of 14.0%.

[0032] (2) To 12.0m 3 Add 5.5m 3 240.0L of pure water, 240.0L of ammonia water and 63.0L of dilute alkali were introduced into the reactor at a flow rate of 0.8m 3 / h of nitrogen, turn on the single-layer paddle for stirring, set the speed to 200-360r / min, mix the bottom liquid evenly, raise the temperature to 55-65℃ and maintain stable, control the pH value of the bottom liquid at 11.40-12.48, the ammonia concentration at 6.0-12g / L, and the alkali concentration at 14.5-24.5g / L.

[0033] (3) After the bottom liquid in the reactor reaches the above conditions, a certain flow rate of ternary liquid, liquid alkali and ammonia water is added to the reactor at the same time by controlling the mass flowmeter. After maintaining the reaction under high pH conditions for 4-10 hours, the pH value is reduced to 10.15-11.40 within 10-25 hours by controlling the flow rate of dilute alkali. At the same time, the ammonia flow rate is controlled to maintain the ammonia concentration and total alkalinity at 6.2-10.2g / L and 14.5-24.5g / L respectively. The reaction is carried out under this condition until the particles grow to a D50 of 3.3-3.7μm and then the feeding is stopped.

[0034] (5) The slurry obtained by the reaction is pumped into a filter press and washed twice with 45-55°C dilute alkali and 50-60°C pure water, each washing for 8-15 minutes. After drying, a new type of low-sulfur and low-tap density ternary precursor small particles is obtained. The sulfur content of the material is 634ppm as detected by ICP, and the tap density of the material is 1.32g / cm 3 .

[0035] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing small particles of a low-sulfur and low-tap density ternary precursor, characterized in that: The following steps are involved: (1) preparing a ternary solution: using nickel sulfate, cobalt sulfate and manganese sulfate as raw materials, preparing a sulfate mixed solution with a total concentration of 100.0-120.0 g / L, and controlling the molar ratio of nickel, cobalt and manganese in the sulfate mixed solution to be (4-8): (0.5-3): (1-4); (2) preparing the base liquid: nitrogen is introduced into the reaction kettle as a protective gas, a certain amount of pure water, liquid alkali with a mass concentration of 25.0%-30.0%, and ammonia water with a mass concentration of 12.0-20.0% are added as the base liquid, and the base liquid is stirred at a certain temperature to mix uniformly, and the pH value of the base liquid is controlled to be 11.30-12.50, the ammonia concentration is 5.0-8.0 g / L, and the alkali concentration is 12.0-25.0 g / L; (3) co-precipitation reaction: adding the sulfate solution prepared in step (1) together with liquid alkali and ammonia water to the reactor described in step (2) at a certain rate to carry out a co-precipitation reaction, controlling the temperature of the reaction system to be 40.0-65.0° C. and the stirring rate of the reactor to be 150-360 r / min; (4) Particle growth: The rate at which the liquid alkali and ammonia water are added to the reactor is adjusted so that the pH value of the reaction system drops to 10.10-11.40 within 4.0-20.0 h, while maintaining the ammonia concentration and the alkali concentration at 5.0-12.0 g / L and 13.0-25.0 g / L, respectively. The pH value is then stabilized at 10.10-11.40 until the ternary precursor particles in the reaction system grow to a D50 of 3.3-3.7 μm, and then the reaction is terminated; The sulfur content of the prepared ternary precursor small particles is less than 700ppm, and the tap density is less than 1.35g / cm 3 .

2. The method for preparing low-sulfur and low-tap density ternary precursor small particles according to claim 1, characterized in that: The temperature in step (2) is 40.0-65.0°C.

3. The method for preparing low-sulfur and low-tap density ternary precursor small particles according to claim 1, characterized in that: The stirring in step (2) uses a single-layer paddle with a stirring rate of 150-360 r / min.

4. The method for preparing low-sulfur and low-tap density ternary precursor small particles according to claim 1, characterized in that: The method further comprises step (5): washing the slurry obtained by the reaction in step (4) with hot diluted alkali and pure water for multiple times, and then drying to obtain the low-sulfur and low-tap density ternary precursor small particles.

5. The method for preparing low-sulfur and low-tap density ternary precursor small particles according to claim 4, characterized in that: The mass concentration of the dilute alkali in step (5) is 2.0%-3.5%, the temperature is 40.0-70.0°C, and the temperature of the pure water is 40.0-70.0°C.

6. A low-sulfur, low-tap density ternary precursor prepared by the method according to any one of claims 1 to 5.

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