CN112919552B - High tap density multi-element oxide precursor and preparation method and preparation system thereof - Google Patents

Abstract

The invention relates to the technical field of powder material preparation methods, in particular to a high-tap-density multi-element oxide precursor, a preparation method and a preparation system thereof. The preparation method comprises the following steps: s1, adding metal salt containing crystal water into a liquid conveying device according to the stoichiometric ratio of each metal element in the multi-element oxide, stirring, heating and melting to obtain sub-molten salt liquid; s2, atomizing the sub-molten salt liquid through a two-fluid atomizer to form atomized liquid drops, and bringing the atomized liquid drops into a fluidized bed pyrolysis furnace by utilizing compressed gas for pyrolysis; and S3, collecting the pyrolysis product obtained in the step S2 through a dust collector to obtain the high tap density multi-element oxide precursor material. The method combines sub-molten salt liquid, two-fluid atomization and fluidized bed pyrolysis, realizes the high-efficiency preparation of the high-tap-density multi-element oxide precursor, and the precursor has the advantages of uniform element distribution, uniform particle size, high purity and good spherical morphology.

Description

High tap density multicomponent oxide precursor and preparation method and preparation system thereof

technical field

The invention relates to the technical field of powder material preparation methods, in particular to a high tap density multi-element oxide precursor and a preparation method and preparation system thereof.

Background technique

With the intensification of the greenhouse effect and the exhaustion of fossil energy, the development of new energy has gradually become a hot spot of people's attention. Lithium-ion batteries are widely used in portable electronic products, energy storage devices and new energy vehicles due to their high energy density, long cycle life, and good safety performance. However, in order to meet the cruising range requirements of new energy vehicles, lithium-ion batteries with higher energy density are required. Layered nickel-based multi-component cathode materials (LiNixCoyMzO2, M=Mn, Al; x>0.6) have the advantages of high specific capacity and low cost, and are considered to be one of the most promising cathode materials for lithium-ion power batteries.

At present, the preparation method of commercial nickel-based multi-material precursors is mainly hydroxide co-precipitation method. Although this method can produce multi-component oxide precursors with controllable morphology and good mechanical properties, the co-precipitation process is lengthy, complicated in operation, harsh in synthesis conditions, poor in uniformity of material composition, and high in production cost. hindering its application in mass production. Compared with the traditional cathode material synthesis method, the spray pyrolysis method has many advantages such as short process, strong adaptability to raw materials, simple process, large production capacity and high production efficiency, which is beneficial to industrial production. Chinese patent document CN106784780A discloses a method for preparing an oxide precursor of a ternary positive electrode material for lithium ion batteries. The method uses metal chloride solution as raw material and rapidly prepares ternary lithium ion batteries with good sphericity through ultrasonic spray pyrolysis. Cathode material oxide precursor. However, with the development of the times and the popularization of new energy vehicles and smart electronic devices, the demand for energy density and power density of lithium-ion batteries is getting higher and higher. Spray pyrolysis is a fast multiphase reaction process. The rapid evaporation of the solvent during the pyrolysis process will impact the primary particles, so that the prepared materials are often porous or hollow. Requirements for high energy density of lithium-ion batteries. Therefore, how to prevent the precursor from forming a porous or hollow structure during the spray pyrolysis process and increase the primary particles of the material is the key to the preparation of high-tap density nickel-based cathode material precursors by spray pyrolysis.

SUMMARY OF THE INVENTION

In view of the above-mentioned problems existing in the prior art, the present invention adopts the metal salt containing crystal water to obtain a sub-molten salt liquid, that is, a high-concentration precursor solution by a direct melting method, according to the reason that a high tap density nickel-based material cannot be obtained, and then uses the compressed The gas atomizes the sub-molten salt liquid through a dual-flow atomizer, and pyrolyzes to obtain a multi-element oxide precursor with high tap density. The precursor obtained by this method is a large-diameter solid particle with high tap density and uniform element distribution. , the particle size is uniform.

In order to achieve the above purpose of the invention, the present invention provides a preparation method of a high tap density multi-component oxide precursor, which specifically includes:

S1: according to the stoichiometric ratio of each metal element in the multi-element oxide, the metal salt containing crystal water is added in the liquid feeding device to carry out stirring and heating melting to obtain sub-molten salt liquid;

S2: the sub-molten salt liquid is atomized by a two-fluid atomizer to form atomized droplets, and the compressed gas is utilized to bring the atomized droplets into a fluidized bed pyrolysis furnace for pyrolysis;

S3: the pyrolysis product of step S2 is collected by a dust collector to obtain a multi-component oxide precursor material with high tap density.

Further, the metal salts include nitrates or/and chlorides of nickel, cobalt and manganese/aluminum; the stoichiometric ratio is that the stoichiometric ratio of nickel, cobalt, and manganese/aluminum is x:y:z, so The x:y:z is (0.33～1):(0～0.33):(0～0.33); the sub-molten salt liquid can also be doped with Al, Mg, Zr, Ti, Mo, W, B and One or more of P; the doping element in the multi-element oxide precursor does not exceed 5%.

Further, the heating and melting temperature is 60-250°C, preferably 80-180°C. The moisture content of the sub-molten salt liquid is 1%-50%.

Further, the particle size of the atomized droplets is 1-50 μm.

Further, the compressed gas is one of oxygen or air.

Further, the process conditions for the pyrolysis of the fluidized bed pyrolysis furnace are: a temperature of 650-950° C. and a time of 10-50 minutes.

Based on the same inventive concept, the present invention provides a preparation system for a high tap density multi-component oxide precursor, the preparation system specifically includes a dust collector, a fluidized bed, a dual-flow atomizer, a heater, a filter, a blower, a Hydraulic device and exhaust fan;

The bottom of the fluidized bed is provided with a fluidized gas inlet, and the fluidized gas inlet is sequentially connected to a heater, a filter and a blower; the top of the fluidized bed is provided with a dust collector for collecting pyrolysis products , the dust collector is connected with an exhaust fan;

The two-fluid atomizer is arranged at the center of the fluidized bed cavity, the atomizer is connected to compressed gas through a gas pipe, and the liquid feeding device is connected to the dual-flow atomizer through a peristaltic pump.

Further, the nozzle diameter of the atomizing nozzle of the dual-flow atomizer is 0.5-2.0 mm, preferably 0.7-1.0 mm. The maximum spray angle of the atomizing nozzle is appropriately adjusted according to the diameter of the cavity, which not only ensures that the material is evenly dispersed in the entire cavity, but also prevents the material from being directly sprayed onto the inner wall of the cavity due to the large spray angle, resulting in the loss of effective reaction materials.

Further, the preparation system further includes a tail gas treatment device, and the tail gas treatment device is connected with the exhaust fan, and is used for removing the waste gas generated in the pyrolysis process.

Further, the dust collector is a bag type dust collector or an electrostatic collector. The diameter of the cavity of the fluidized bed 2 is 0.1-5.0m, preferably 1.0-5.0; when the diameter of the cavity is too small, a large amount of materials ejected from the nozzle will adhere to the furnace wall, resulting in a large amount of waste, which is not conducive to production; The power of the blower 7 is 0.75-15Kw; the liquid feeding device 8 is provided with a microwave heating temperature control device; the compressed gas 9 is oxygen or air, preferably oxygen; the gas pressure is 0.4-0.7MPa.

Based on the same inventive concept, the present invention provides a high tap density multi-component oxide precursor prepared by the above preparation method.

Beneficial effects:

(1) The present invention combines two-fluid atomization with fluidized bed pyrolysis, realizes the efficient preparation of multi-component metal oxide precursors by spray pyrolysis of sub-molten salt, and effectively solves the problem of traditional spray pyrolysis method for preparing powder materials. low density problem. The principle may be: based on the principle of preparing powder materials by spray pyrolysis, increasing the number of primary particles in the atomized droplets can effectively increase the particle size and density of the prepared powder materials, thereby improving the vibration of the powder materials. density. The sub-molten salt used in the present invention is an unconventional medium between an aqueous solution and a molten salt, and the use of a high-concentration medium such as sub-molten salt as a spray pyrolysis raw material can significantly increase the number of crystalline cores in the atomized droplets, And reduce the volatilization of the solvent, slow down the impact on the primary particles, and help to form large-sized solid particles.

(2) The present invention uses a fluidized bed to pyrolyze the atomized droplets, which can effectively prolong the residence time of the reactants in the pyrolysis furnace, promote crystal growth, and improve the tap density of powder materials. At the same time, the longer pyrolysis time can make the metal salt hydrolysis reaction more fully, effectively remove impurity ions (Cl ^- , HNO3 ^- etc.), so that the prepared material has higher purity. Compared with traditional atomization methods (such as ultrasonic atomization, electrostatic atomization, etc.), the two-fluid atomization method adopted in the present invention has strong adaptability to raw materials, and can realize various fluids such as high viscosity, colloid, and suspension liquid. The atomization, the effect is good. The multi-element precursor material with uniform distribution of elements, uniform particle size, high purity and good spherical morphology can be prepared.

(3) In the present invention, the dual-fluid atomizer can realize the efficient atomization of the solution, and the fluidized bed pyrolysis furnace can provide a larger reaction space and simultaneously pyrolyze a large number of solid particles. Therefore, compared with the traditional spray pyrolysis method, the present invention has higher yield, can realize the rapid preparation of nickel-based multi-element oxide precursor, and is beneficial to promote the large-scale production and application of nickel-based multi-element cathode material.

(4) The metal salts used in the present invention are all hydrates, with low melting point and high concentration, and can be melted at a lower temperature to form the required sub-molten salt, which is beneficial to saving energy consumption and is suitable for industrial application.

Description of drawings

FIG. 1 is a schematic diagram of a preparation system of a high tap density multi-component oxide precursor provided in an embodiment of the present invention.

[Description of reference numerals]

1. Dust collector; 2. Fluidized bed; 3. Atomizer; 4. Fluidized gas inlet; 5. Heater; 6. Filter; 7. Blower; 8. Liquid feeding device; 9. Compressed gas; 10. Exhaust fan.

Detailed ways

In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to specific embodiments, but the protection scope of the present invention is not limited to the following specific embodiments.

Unless otherwise defined, all technical terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments, and are not intended to limit the protection scope of the present invention.

Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or can be prepared by existing methods.

The process flow for preparing the precursor in the preparation system of the high tap density multi-component oxide precursor provided by the present invention is as follows:

Step 1: Preheating the furnace body: Turn on the heater 5 to heat up to 650-950°C, then turn on the blower 7 to filter the air through the filter 6 and preheat the cavity of the fluidized bed 2 through the fluidized gas inlet 4;

Step 2 Heating and melting: Weigh the metal salt containing crystal water according to the stoichiometric ratio of each metal element in the multi-element oxide, place the metal salt in the liquid feeding device 8, heat to 60-250 ° C, and melt to obtain a sub-molten salt liquid;

Step 3: Spray pyrolysis: under the action of the compressed gas 9, the sub-molten salt liquid is sprayed into the fluidized bed 2 through the atomizer 3, and pyrolyzed to generate a multi-component oxide precursor;

Step 4: Dust collection: the applied multi-component oxide precursor is collected by the dust collector 1, and discharged through the exhaust fan 10 for a period of time for exhaust gas treatment or recovery.

Example 1

This embodiment adopts the preparation system shown in FIG. 1 to prepare the NCM ternary cathode precursor, which specifically includes the following steps:

Step 1 Preheating of the furnace body: Turn on the heater 5 to raise the temperature to 800°C, then turn on the blower 7 to filter the air through the filter 6 and then preheat the fluidized bed 2 cavity through the fluidized gas inlet 4, and the fluidized bed 2 cavity The body temperature is controlled at 800°C;

Step 2 Heating and melting: Weigh nickel chloride hexahydrate, cobalt chloride hexahydrate, and manganese chloride tetrahydrate in a certain stoichiometric ratio to a total of 500 g, place them in the liquid feeding device 8, heat to 60-250 ° C, while Stir while melting to form a uniform sub-molten salt liquid;

Step 3 Spray pyrolysis: After the spray pyrolysis device runs stably, inject the sub-molten salt liquid obtained in step 2 into the two-fluid atomizer 3 at a speed of 5L/h through a peristaltic pump, and carry out mixed atomization with the compressed air 9 , the nozzle mouth is 0.75mm, and the air pressure is 0.4MPa. The atomized droplets are sprayed into the fluidized bed pyrolysis furnace 2 under the action of air pressure for pyrolysis, the pyrolysis temperature is 800°C, and the residence time is 30 minutes.

Step 4 Dust collection: the pyrolysis product obtained in step 3 is collected by the bag filter 1, and the exhaust gas is discharged through the exhaust fan 10 for treatment or recovery. When the molten salt liquid is exhausted, continue to inject air, and stop the furnace after 15 minutes. , and when the temperature drops to room temperature, the dust collector is removed and recovered to obtain the required high tap density NCM precursor material. The tap density values of the obtained precursor materials are shown in Table 1.

Table 1 The tap density of the precursor material obtained in Example 1

Example 2

This embodiment uses the preparation system shown in Figure 1 to prepare the NCM622 ternary cathode precursor, which specifically includes the following steps:

Step 1 Preheating of the furnace body: Turn on the heater 5 to raise the temperature to 650-950°C, then turn on the blower 7 to filter the air through the filter 6 and then preheat the cavity of the fluidized bed 2 through the fluidized gas inlet 4, and the fluidized bed 2. The temperature in the cavity is controlled at 650-950℃;

Step 2 Heating and melting: Nickel chloride hexahydrate, cobalt chloride hexahydrate, and manganese chloride tetrahydrate are weighed in a stoichiometric ratio of 0.6:0.2:0.2 to a total of 500g, placed in the liquid feeding device 8, and heated to 125° C. , stirring while melting to form a uniform sub-molten salt liquid;

Step 3 Spray pyrolysis: After the spray pyrolysis device runs stably, inject the sub-molten salt liquid obtained in step 2 into the two-fluid atomizer 3 at a speed of 5L/h through a peristaltic pump, and carry out mixed atomization with the compressed air 9 , the nozzle mouth is 0.75mm, and the air pressure is 0.4MPa. The atomized droplets are sprayed into the fluidized bed pyrolysis furnace 2 under the action of air pressure for pyrolysis, the pyrolysis temperature is 650-950°C, and the residence time is 1-180min.

Step 4 Dust collection: the pyrolysis product obtained in step 3 is collected by the bag filter 1, and the exhaust gas is discharged through the exhaust fan 10 for treatment or recovery. When the molten salt liquid is exhausted, continue to inject air, and stop the furnace after 15 minutes. , and when the temperature drops to room temperature, the dust collector is removed and recovered to obtain the required high tap density ternary doped precursor material. The tap density of the obtained precursor material is shown in Table 2.

Table 2 The tap density of the precursor material obtained in Example 2

Example 3

In this example, the preparation system shown in FIG. 1 is used to prepare the Al-doped NCM811 ternary cathode precursor, which specifically includes the following steps:

Step 1 Preheating of the furnace body: Turn on the heater 5 to raise the temperature to 850°C, then turn on the blower 7 to filter the air through the filter 6 and then preheat the fluidized bed 2 cavity through the fluidized gas inlet 4, and the fluidized bed 2 cavity The body temperature is controlled at 850°C;

Step 2 Heating and melting: Nickel chloride hexahydrate, cobalt chloride hexahydrate, and manganese chloride tetrahydrate are weighed in a stoichiometric ratio of 0.85:0.1:0.05 to a total of 500g, placed in the liquid feeding device 8, and heated to 150 ° C , stirring while melting to form a uniform sub-molten salt liquid;

Step 3 Spray pyrolysis: After the spray pyrolysis device runs stably, inject the sub-molten salt liquid obtained in step 2 into the two-fluid atomizer 3 at a speed of 5L/h through a peristaltic pump, and carry out mixed atomization with the compressed air 9 , the nozzle mouth is 0.75mm, and the air pressure is 0.4MPa. The atomized droplets are sprayed into the fluidized bed pyrolysis furnace 2 under the action of air pressure for pyrolysis, the pyrolysis temperature is 850°C, and the residence time is 40 minutes.

Step 4 Dust collection: the pyrolysis product obtained in step 3 is collected by the bag filter 1, and the exhaust gas is discharged through the exhaust fan 10 for treatment or recovery. When the molten salt liquid is exhausted, continue to inject air, and stop the furnace after 15 minutes. , and when the temperature drops to normal temperature, the dust collector is removed for recycling to obtain the desired high tap density ternary doped precursor material, and its tap density is 2.41 g/cm ³ .

According to the above examples and the tap density of the obtained precursor material, the maximum can reach 2.42 g/cm ³ . It can be seen that the multi-component oxide precursor obtained by the preparation method of the present invention has a high tap density, which can meet the requirements of lithium battery cathode materials. In addition, the preparation method is simple, can realize the rapid preparation of nickel-based multi-element oxide precursors, and is beneficial to promote the large-scale production and application of nickel-based multi-element cathode materials.

The above-mentioned embodiments are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The equivalent replacement or change of the solution and its concept shall be included within the protection scope of the present invention.

Claims (5)

1. a preparation method of high tap density multi-element oxide precursor, is characterized in that, specifically comprises: S1: according to the stoichiometric ratio of each metal element in the multi-element oxide, the metal salt containing crystal water is added in the liquid feeding device to carry out stirring and heating melting to obtain sub-molten salt liquid; S2: the sub-molten salt liquid is atomized by a two-fluid atomizer to form atomized droplets, and the compressed gas is utilized to bring the atomized droplets into a fluidized bed pyrolysis furnace for pyrolysis; S3: the pyrolysis product of step S2 is collected by a dust collector to obtain a high tap density multi-element oxide precursor material; The metal salts include nitrates or/and chlorides of nickel, cobalt and manganese/aluminum; the stoichiometric ratio is that the stoichiometric ratio of nickel, cobalt, and manganese/aluminum is x:y:z, and the x: y:z is (0.33~1):(0~0.33):(0~0.33); the sub-molten salt liquid can also be doped with Al, Mg, Zr, Ti, Mo, W, B and P. One or more; the multi-element oxide precursor doping element does not exceed 5%; The multicomponent oxide precursors are solid particles. 2 . The method for preparing a high tap density multi-component oxide precursor according to claim 1 , wherein the heating and melting temperature is 60-250° C. 3 . 3 . The method for preparing a high tap density multi-component oxide precursor according to claim 1 , wherein the particle size of the atomized droplets is 1-50 μm. 4 . 4 . The method for preparing a high tap density multi-component oxide precursor according to claim 1 , wherein the compressed gas is one of oxygen or air. 5 . 5. The preparation method of high tap density multi-component oxide precursor according to claim 1, characterized in that, the process conditions of the fluidized bed pyrolysis furnace pyrolysis are: temperature 650-950 ℃, time 10-50min .

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