A method for improving the uniformity of precursor coating

Abstract

The present invention discloses a method for improving the uniformity of precursor coating, which comprises the following steps: preparing a nickel-cobalt-manganese mixed ternary solution, a zirconium sulfate solution, and a cobalt sulfate solution; preparing a bottom liquid in a first reaction kettle, introducing N2, and starting stirring; simultaneously pumping the nickel-cobalt-manganese mixed ternary solution, the zirconium sulfate solution, ammonia water, and a NaOH solution into the first reaction kettle for coprecipitation reaction, and stopping feeding after the crystal grains grow to a particle size D50 of 3.0 - 20.0 μm to obtain a first-stage slurry; transferring the first-stage slurry into a second reaction kettle; simultaneously pumping the cobalt sulfate solution, ammonia water, and a NaOH solution into the second reaction kettle for surface coating reaction, and stopping feeding after the crystal grains grow to a particle size D50 of 4.0 - 21.0 μm, and the obtained qualified slurry is washed, dehydrated, dried, screened, deironed, and packaged to obtain the finished product. The present invention can solve the problem of uneven surface coating of particles in the reaction coating stage.

Description

Technical Field

[0001] The present invention belongs to the technical field of material chemistry, and particularly relates to a method for improving the uniformity of precursor coating. Background Art

[0002] The doped-coated precursor is an important raw material for preparing high-performance cathode materials, with broad development and application prospects. In the traditional batch process for preparing the precursor, the reaction system is a reaction kettle - thickener. In the coating reaction stage, due to the insufficient adequacy and timeliness of the material circulation between the concentrator and the reaction kettle, a large number of crystal particles are not effectively coated, resulting in insufficient cycle life of the subsequent produced cathode material and ultimately affecting the battery performance. Summary of the Invention

[0003] Aiming at the problems in the prior art, the present invention provides a method for improving the uniformity of precursor coating, which can solve the problem of uneven coating on the particle surface in the reaction coating stage and improve the cycle life of the cathode material.

[0004] The present invention adopts the following technical solutions:

[0005] A method for improving the uniformity of precursor coating, the method comprising the following steps:

[0006] (1) Prepare a nickel-cobalt-manganese mixed ternary solution with a concentration of 10 - 150 g / L, and the molar ratio of Ni, Co, and Mn in the nickel-cobalt-manganese mixed ternary solution is 60 - 98:1 - 20:1 - 20; prepare a zirconium sulfate solution with a concentration of 1 - 50 g / L; prepare a cobalt sulfate solution with a concentration of 10 - 150 g / L;

[0007] (2) Prepare a bottom liquid in a first reaction kettle, the temperature of the bottom liquid is 40 - 80 °C, the ammonia concentration is 1 - 10 g / L, the pH value is 9.0 - 13.0, introduce N2 into the first reaction kettle, and start stirring the first reaction kettle;

[0008] (3) Simultaneously pump the nickel-cobalt-manganese mixed ternary solution, zirconium sulfate solution, ammonia water, and NaOH solution into the first reaction kettle for coprecipitation reaction, control the temperature of the first reaction kettle to be 40 - 80 °C, the stirring speed to be 50 - 400 r / min, control the ammonia concentration of the slurry in the first reaction kettle to be 1 - 10 g / L, the pH value to be 9.0 - 13.0, and stop feeding after the crystal particles in the first reaction kettle grow to a particle size D50 of 3.0 - 20.0 μm to obtain the first-stage slurry;

[0009] (4) Transfer the first-stage slurry into a second reaction kettle, and control the temperature, pH, ammonia concentration, and alkali concentration of the second reaction kettle to be the same as those of the first reaction kettle;

[0010] (5) Pump the cobalt sulfate solution, ammonia water, and NaOH solution into the second reaction kettle simultaneously for surface coating reaction. Control the slurry temperature in the second reaction kettle at 40 - 80 °C, the stirring speed at 50 - 400 r / min, the ammonia concentration at 1 - 10 g / L, and the pH value at 9.0 - 13.0. Stop feeding after the crystal particles in the second reaction kettle grow to a particle size D50 of 4.0 - 21.0 μm to obtain qualified slurry;

[0011] (6) Wash, dehydrate, dry, screen, remove iron, and package the qualified slurry to obtain the finished product.

[0012] Further, the volume of the first reaction kettle is 1 - 10 m 3 , and the volume of deionized pure water in the bottom liquid is 0.5 - 5 m 3 .

[0013] Further, the volume of the second reaction kettle is 15 - 30 m 3 , and transfer the first-stage slurry into the second reaction kettle through a mass flowmeter in step (4).

[0014] Further, in step (3), pump the nickel-cobalt-manganese mixed ternary solution, zirconium sulfate solution, ammonia water with a mass concentration of 10 - 30%, and NaOH solution with a mass concentration of 10 - 50% into the first reaction kettle simultaneously for coprecipitation reaction.

[0015] Further, in step (3), pump the nickel-cobalt-manganese mixed ternary solution, zirconium sulfate solution, ammonia water, and NaOH solution into the first reaction kettle simultaneously for coprecipitation reaction at flow rates of 100 - 150 L / h, 30 - 50 L / h, 10 - 20 L / h, and 10 - 30 L / h respectively.

[0016] Further, in step (5), pump the cobalt sulfate solution, ammonia water with a mass concentration of 10 - 30%, and NaOH solution with a mass concentration of 10 - 50% into the second reaction kettle simultaneously for surface coating reaction.

[0017] Further, in step (5), pump the cobalt sulfate solution, ammonia water, and NaOH solution into the second reaction kettle simultaneously for surface coating reaction at flow rates of 50 - 60 L / h, 15 - 25 L / h, and 6 - 10 L / h respectively.

[0018] Further, the flow rate of N2 introduced into the first reaction kettle in step (2) is 0.5 - 5.0 m 3 / h.

[0019] Advantageous technical effects of the present invention: By eliminating the concentrator in the reaction coating stage, the present invention fundamentally solves the problem of non-uniform coating. By selecting a reaction kettle with an appropriate volume and precisely controlling the usage amount of the slurry before coating and the input amount of the salt solution during the coating process, the problem of non-uniform coating on the particle surface in the reaction coating stage is solved, greatly improving the cycle life of the cathode material. For the prepared product particles, EPMA is detected, showing good coating effect. The present invention precisely controls the usage amount of the coating salt solution and the final molar ratio after coating; the operation of the present invention is convenient and is conducive to large-scale production and popularization. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is the process flow chart of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] See Figure 1 , a method for improving the coating uniformity of the precursor of the present invention, comprising the following steps:

[0022] (1) Prepare a nickel-cobalt-manganese mixed ternary solution with a concentration of 10-150 g / L, and the molar ratio of Ni, Co, and Mn in the nickel-cobalt-manganese mixed ternary solution is 60-98:1-20:1-20; prepare a zirconium sulfate solution with a concentration of 1-50 g / L; prepare a cobalt sulfate solution with a concentration of 10-150 g / L;

[0023] (2) Prepare a bottom liquid in the first reaction kettle, the temperature of the bottom liquid is 40-80 °C, the ammonia concentration is 1-10 g / L, the pH value is 9.0-13.0, introduce N2 into the first reaction kettle, and start stirring the first reaction kettle; the volume of the first reaction kettle is 1-10 m 3 , and the volume of deionized pure water in the bottom liquid is 0.5-5 m 3 . The flow rate of N2 introduced into the first reaction kettle is 0.5-5.0 m 3 / h..

[0024] (3) Simultaneously pump the nickel-cobalt-manganese mixed ternary solution, zirconium sulfate solution, ammonia water, and NaOH solution into the first reaction kettle through the inlet pipe for coprecipitation reaction. Control the temperature of the first reaction kettle at 40 - 80 °C and the stirring speed at 50 - 400 r / min. By adjusting the flow rates of the liquid alkali and ammonia water, control the ammonia concentration in the slurry in the first reaction kettle at 1 - 10 g / L and the pH value at 9.0 - 13.0. After the crystal particles in the first reaction kettle grow to a particle size D50 of 3.0 - 20.0 μm, stop feeding to obtain the first-stage slurry. Simultaneously pump the nickel-cobalt-manganese mixed ternary solution, zirconium sulfate solution, ammonia water with a mass concentration of 10 - 30%, and NaOH solution with a mass concentration of 10 - 50% into the first reaction kettle for coprecipitation reaction. Pump the nickel-cobalt-manganese mixed ternary solution, zirconium sulfate solution, ammonia water, and NaOH solution into the first reaction kettle for coprecipitation reaction at flow rates of 100 - 150 L / h, 30 - 50 L / h, 10 - 20 L / h, and 10 - 30 L / h respectively.

[0025] (4) Transfer the first-stage slurry into the second reaction kettle, and control the temperature, pH, ammonia concentration, and alkali concentration in the second reaction kettle to be the same as those in the first reaction kettle. The volume of the second reaction kettle is 15 - 30 m 3 In step (4), transfer the first-stage slurry into the second reaction kettle through a mass flowmeter.

[0026] (5) According to the quantity of the transferred first-stage slurry, accurately calculate the dosage of cobalt sulfate solution required for coating. Simultaneously pump the cobalt sulfate solution, ammonia water, and NaOH solution into the second reaction kettle for surface coating reaction. Control the slurry temperature in the second reaction kettle at 40 - 80 °C, the stirring speed at 50 - 400 r / min, the ammonia concentration at 1 - 10 g / L, and the pH value at 9.0 - 13.0. After the crystal particles in the second reaction kettle grow to a particle size D50 of 4.0 - 21.0 μm, stop feeding to obtain the qualified slurry. Simultaneously pump the cobalt sulfate solution, ammonia water with a mass concentration of 10 - 30%, and NaOH solution with a mass concentration of 10 - 50% into the second reaction kettle for surface coating reaction. Pump the cobalt sulfate solution, ammonia water, and NaOH solution into the second reaction kettle for surface coating reaction at flow rates of 50 - 60 L / h, 15 - 25 L / h, and 6 - 10 L / h respectively.

[0027] (6) Wash, dehydrate, dry, screen, remove iron, and package the qualified slurry to obtain the finished quaternary precursor.

[0028] To further understand the technical content, features, and effects of the present invention, the following examples are used to further illustrate the present invention, but are not limited thereto.

[0029] Example 1

[0030] Prepare a nickel-cobalt-manganese ternary sulfate solution with a concentration of 50 g / L and a molar ratio of 75:5:20. Separately prepare a zirconium sulfate solution with a concentration of 20 g / L, a cobalt sulfate solution with a concentration of 50 g / L, an NaOH aqueous solution with a mass percentage concentration of 10%, and an ammonia water with a mass percentage concentration of 10%.

[0031] Add 4 m 3 to the first reaction kettle 3 Add deionized water, 250 L of NaOH solution with a mass concentration of 10%, and 150 L of ammonia water with a mass percentage concentration of 10% to prepare the bottom liquid. Start stirring the first reaction kettle and adjust the pH of the bottom liquid to 12 and the ammonia concentration to 8.5 g / L. Introduce 0.5 m 3 / h of N2 and heat up to 40 °C and maintain stability.

[0032] Set the stirring speed to 300 rpm / min. Accurately pump the prepared nickel-cobalt-manganese ternary sulfate solution, zirconium sulfate solution, NaOH solution, and ammonia water into the first reaction kettle at a flow rate of 150 L / h, 50 L / h, 20 L / h, and 20 L / h respectively through a flow meter. By adjusting the dosages of NaOH and ammonia water, control the ammonia value of the supernatant to be stable at 5 - 10 g / L and the pH value to be stable at 9.0 - 12.0.

[0033] When the particle size D50 in the first reaction kettle reaches 6.0 μm, stop the reaction and transfer the slurry in the first reaction kettle to the second reaction kettle.

[0034] Add to 15 m 3 Pump the prepared cobalt sulfate solution, NaOH solution, and ammonia water into the second reaction kettle at a flow rate of 50 L / h, 15 L / h, and 6 L / h simultaneously. By adjusting the dosages of NaOH and ammonia water, control the ammonia value of the supernatant to be stable at 3 - 8 g / L and the pH value to be 9.0 - 12.0. When the secondary particle size D50 in the second reaction kettle reaches 6.5 μm, stop feeding and the reaction ends to obtain a qualified slurry.

[0035] After subjecting the obtained qualified slurry to processes such as washing, drying, screening, iron removal, and packaging, prepare the finished product.

[0036] Example 2

[0037] Prepare a nickel-cobalt-manganese ternary sulfate solution with a concentration of 110 g / L and a molar ratio of 85:1:14. Separately prepare a zirconium sulfate solution with a concentration of 50 g / L, a cobalt sulfate solution with a concentration of 100 g / L, an NaOH aqueous solution with a mass percentage concentration of 20%, and an ammonia water with a mass percentage concentration of 20%.

[0038] Add to 6.0 m 3 to the first reaction kettle 3Deionized water, 150 L of NaOH solution with a mass concentration of 20%, and 80 L of ammonia water with a mass percentage concentration of 20% are used to prepare the bottom liquid. Start stirring the first reaction kettle, adjust the pH of the bottom liquid to 13 and the ammonia concentration to 10 g / L, and introduce 0.5 m 3 / h of N2, and heat up to 50 °C and maintain stability.

[0039] Set the stirring speed to 300 rpm / min, and accurately pump the prepared nickel-cobalt-manganese ternary sulfate solution, zirconium sulfate solution, NaOH solution, and ammonia water into the first reaction kettle at a flow rate of 100 L / h, 30 L / h, 15 L / h, and 30 L / h respectively through a flow meter. By adjusting the dosage of NaOH and ammonia water, control the ammonia value of the supernatant to be stable at 5 - 10 g / L and the pH value to be stable at 10.0 - 13.0.

[0040] When the particle size D50 in the first reaction kettle reaches 6.0 μm, stop the reaction, and transfer the slurry to the second reaction kettle.

[0041] Into 15 m 3 Simultaneously pump the prepared cobalt sulfate solution, NaOH solution, and ammonia water into the second reaction kettle at a flow rate of 60 L / h, 25 L / h, and 10 L / h. By adjusting the dosage of NaOH and ammonia water, control the ammonia value of the supernatant to be stable at 3 - 8 g / L and the pH value to be 9.0 - 12.0. When the secondary particle size D50 in the second reaction kettle reaches 6.5 μm, stop feeding, and the reaction ends to obtain a qualified slurry.

[0042] Wash, dry, screen, remove iron, and package the above-mentioned obtained qualified slurry to prepare the finished product.

[0043] Example 3

[0044] Prepare a nickel-cobalt-manganese ternary sulfate solution with a concentration of 140 g / L and a molar ratio of 90:1:9, and respectively prepare a zirconium sulfate solution with a concentration of 40 g / L, a cobalt sulfate solution with a concentration of 90 g / L, an NaOH aqueous solution with a mass percentage concentration of 25%, and an ammonia water with a mass percentage concentration of 17%.

[0045] Into 10.0 m 3 Add 5.0 m 3 Deionized water, 230 L of NaOH solution with a mass concentration of 25%, and 140 L of ammonia water with a mass percentage concentration of 17% are used to prepare the bottom liquid. Start stirring the first reaction kettle, adjust the pH of the bottom liquid to 12 and the ammonia concentration to 10 g / L, and introduce 2 m 3 / h of N2, and heat up to 60 °C and maintain stability.

[0046] Set the stirring speed to 320 rpm / min, and accurately pump the prepared nickel-cobalt-manganese ternary sulfate solution, zirconium sulfate solution, NaOH solution and ammonia water into the first reactor at flow rates of 150 L / h, 50 L / h, 10 L / h, and 15 L / h respectively through a flow meter. By adjusting the dosages of NaOH and ammonia water, control the ammonia value of the supernatant to be stable at 4 - 8 g / L and the pH value to be stable at 9.0 - 12.0.

[0047] Stop the reaction when the particle size D50 in the first reactor reaches 13.0 μm, and transfer the slurry to the second reactor.

[0048] To 30 m 3 Pump the prepared cobalt sulfate solution, NaOH solution and ammonia water into the second reactor at the same time at flow rates of 60 L / h, 20 L / h, and 10 L / h. By adjusting the dosages of NaOH and ammonia water, control the ammonia value of the supernatant to be stable at 4 - 8 g / L and the pH value to be 9.0 - 12.0. When the secondary particle size D50 in the second reactor reaches 13.5 μm, stop feeding and end the reaction to obtain a qualified slurry.

[0049] Prepare the finished product by subjecting the obtained qualified slurry to processes such as washing, drying, screening, iron removal, and packaging.

Claims

1. A method for improving the uniformity of precursor coating, characterized in that, The method comprises the following steps: (1) Prepare a nickel-cobalt-manganese mixed ternary solution with a concentration of 10-150 g / L, and the molar ratio of Ni, Co, and Mn in the nickel-cobalt-manganese mixed ternary solution is 60-98:1-20:1-20; prepare a zirconium sulfate solution with a concentration of 1-50 g / L; prepare a cobalt sulfate solution with a concentration of 10-150 g / L; (2) Prepare the bottom liquid in the first reactor. The temperature of the bottom liquid is 40 - 80 °C, the ammonia concentration is 1 - 10 g / L, and the pH value is 9.0 - 13.

0. Introduce N2 into the first reactor and start stirring the first reactor; the volume of the first reactor is 1 - 10 m 3 ; (3) Pump the nickel-cobalt-manganese mixed ternary solution, zirconium sulfate solution, ammonia water, and NaOH solution into the first reaction kettle simultaneously at a flow rate of 100-150 L / h, 30-50 L / h, 10-20 L / h, and 10-30 L / h respectively for coprecipitation reaction. Control the temperature of the first reaction kettle at 40-80 °C and the stirring speed at 50-400 r / min. Control the ammonia concentration in the slurry in the first reaction kettle at 1-10 g / L and the pH value at 9.0-13.

0. Stop feeding after the crystal grains in the first reaction kettle grow to a particle size D50 of 3.0-20.0 μm to obtain the first-stage slurry; (4) Transfer the slurry of the first stage into the second reactor, and control the temperature, pH, ammonia concentration, and alkali concentration of the second reactor to be the same as those of the first reactor; the volume of the second reactor is 15 - 30 m 3 ; (5) Pump the cobalt sulfate solution, ammonia water, and NaOH solution into the second reaction kettle simultaneously at a flow rate of 50-60 L / h, 15-25 L / h, and 6-10 L / h respectively for surface coating reaction. Control the temperature of the slurry in the second reaction kettle at 40-80 °C, the stirring speed at 50-400 r / min, the ammonia concentration at 1-10 g / L, and the pH value at 9.0-13.

0. Stop feeding after the crystal grains in the second reaction kettle grow to a particle size D50 of 4.0-21.0 μm to obtain the qualified slurry; (6) Wash, dehydrate, dry, screen, remove iron, and package the qualified slurry to obtain the finished product.

2. The method for improving the uniformity of precursor coating according to claim 1, characterized in that, The volume of deionized pure water in the base solution is 0.5 - 5 m 3 .

3. The method for improving the uniformity of precursor coating according to claim 1, characterized in that, In step (4), transfer the first-stage slurry into the second reaction kettle through a mass flowmeter.

4. The method for improving the uniformity of precursor coating according to claim 1, characterized in that, In step (3), pump the nickel-cobalt-manganese mixed ternary solution, zirconium sulfate solution, ammonia water with a mass concentration of 10-30%, and NaOH solution with a mass concentration of 10-50% into the first reaction kettle simultaneously for coprecipitation reaction.

5. The method for improving the uniformity of precursor coating according to claim 1, characterized in that, In step (5), pump the cobalt sulfate solution, ammonia water with a mass concentration of 10-30%, and NaOH solution with a mass concentration of 10-50% into the second reaction kettle simultaneously for surface coating reaction.

6. The method for improving the uniformity of precursor coating according to claim 1, characterized in that, The flow rate of N2 introduced into the first reactor in step (2) is 0.5 - 5.0 m 3 / h.

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