CN108314094A - A kind of preparation method of little particle nickel cobalt aluminum hydroxide - Google Patents

Abstract

The invention discloses a preparation method of small particle nickel cobalt aluminum hydroxide. Prepare nickel-cobalt-aluminum mixed solution, ammonium bicarbonate solution, and ammonium monohydrogen phosphate solution; add the mixed solution, ammonium bicarbonate solution, and ammonium monohydrogen phosphate solution to the base solution in parallel, and add hydrogen peroxide and ammonium bicarbonate dropwise after the addition is complete The solution continues to react; after filtration, it is slurried, then ammonia water is added to the slurried material, the temperature is raised to react, and hot pure water is added to wash; after drying with a disc dryer, sieving, iron removal and mixing are carried out to obtain small particle hydroxide nickel cobalt aluminum. The invention obtains nickel-cobalt-aluminum hydroxide with particle diameter less than 2.5 microns, high sphericity, high tap density, phosphorus doping, simple process and low energy consumption.

Description

A kind of preparation method of small particle nickel cobalt aluminum hydroxide

technical field

The invention relates to a method for preparing small-particle nickel-cobalt-aluminum hydroxide, which belongs to the field of lithium battery new energy materials.

Background technique

Power battery performance is the limiting factor that determines the development of electric vehicles. At this stage, the popularization and development of electric vehicles is restricted by problems such as insufficient battery life, slow charging speed, and high cost. This is also the main reason why many consumers are discouraged. Power lithium batteries The price/performance ratio has greatly affected the market popularity of electric vehicles. The positive electrode material is the core key material of the power lithium battery. The energy density of the positive electrode material is closely related to the cruising range of the electric vehicle, and its cost accounts for about 1/3 of the cost of the lithium battery cell. Therefore, a high energy density, long life, high Safe and low-cost cathode materials are crucial to the large-scale commercial use of power lithium batteries and electric vehicles.

At present, there are mainly three schools of technical routes for cathode materials for power lithium batteries at home and abroad: lithium iron phosphate, lithium manganate, and ternary [nickel-cobalt-aluminate lithium (NCA) and nickel-cobalt lithium manganate (NCM)]. Among them, lithium iron phosphate as the positive electrode material has a long charge-discharge cycle life, but its disadvantages are that there is a large gap in energy density, high and low temperature performance, and charge-discharge rate characteristics, and the production cost is high. The technology and application of lithium iron phosphate batteries have been developed. Encountered a bottleneck in development; lithium manganate batteries have low energy density, poor cycle stability and storage performance at high temperatures, so lithium manganate is only used as the positive electrode material for the first generation of power lithium batteries in the world; and multi-component materials have comprehensive performance and The dual advantage of cost has been increasingly concerned and recognized by the industry, gradually surpassing lithium iron phosphate and lithium manganate to become the mainstream technical route. Especially represented by the Tesla (Tesla) electric vehicle, which was suddenly prominent in 2013, the Tesla Model S launched by it has a cruising range of up to 480km, and the positive electrode material used in its cylindrical batteries is NCA. From the perspective of battery energy density and electric vehicle cruising range, nickel (Ni)-containing ternary systems have obvious advantages, especially batteries made of high-Ni ternary system (NCA) materials.

The demand for high-energy-density power lithium batteries has driven the application and continuous improvement of high-specific-capacity high-Ni monolithic materials, and with the hot sales of Tesla in the United States, lithium battery companies such as Panasonic, AESC, and Nissan in Japan and LGC, SKI, and Samsung in South Korea have put Material selection focuses on high-nickel multi-component materials, from conventional LiNi _1/3 Co _1/3 Mn _1/3 O ₂ (abbreviated as NCM111) to high-nickel-content multi-component materials LiNi _0.5 Co _0.2 Mn _0.3 O ₂ (NCM523 for short), LiNi _0.6 Co _0.2 Mn _0.2 O ₂ (NCM622 for short), LiNi _0.8 Co _0.1 Mn _0.1 O ₂ (NCM811 for short) and higher nickel NCA materials with a Ni content of 80% to 89%.

For the nickel-cobalt-lithium-aluminate cathode material, in order to increase its compaction density, that is, to increase its energy density, the current method is to use large particle size nickel-cobalt lithium aluminate and small-particle size nickel-cobalt lithium aluminate for mixed doping , to increase its compaction density, it is generally required that the D50 of small particle size nickel-cobalt-aluminate lithium is less than 3 microns, and the particle size of nickel-cobalt-aluminum hydroxide is required to be less than 2.5 microns, but the conventional co-precipitation process generally cannot obtain Nickel-cobalt-aluminum hydroxide with a particle size of less than 2.5 microns, the resulting small-particle-sized nickel-cobalt-aluminum hydroxide has poor sphericity, low tap density, and high energy consumption.

Contents of the invention

In view of this, the present invention provides a method for preparing small-particle nickel-cobalt-aluminum hydroxide, which can obtain nickel-cobalt-aluminum hydroxide with a particle size of less than 2.5 microns, high sphericity, high tap density, and the realization of phosphorus Doping, simple process and low energy consumption.

The present invention solves the above technical problems by the following technical means:

A kind of preparation method of small particle nickel cobalt aluminum hydroxide, it is the following steps:

(1) Dosing, mix and dissolve nickel-cobalt-aluminum salt into pure water to obtain a nickel-cobalt-aluminum mixed solution, add acid and alkali solution to adjust the pH of the mixed solution to 1.0-1.2, and then remove iron through a fluid iron remover, and then pass through The precision filter is used for precision filtration, and then placed in a constant temperature tank to keep the temperature at 30-35°C; add ammonium bicarbonate to pure water to dissolve, then go through a fluid iron remover for iron removal, and then go through a precision filter for precision filtration. Then put it into a constant temperature tank to keep the temperature at 30-35°C; add ammonium monohydrogen phosphate to pure water to dissolve, then go through a fluid iron remover to remove iron, then pass through a precision filter for precision filtration, and then put it into a constant temperature tank Keep the internal temperature constant until the temperature is 30-35°C;

(2) reaction, the mixed solution that step (1) obtains, ammonium bicarbonate solution and ammonium hydrogen phosphate solution are added in the bottom liquid concurrently, the flow rate of stable mixed solution and the flow rate of ammonium hydrogen phosphate solution, adjust ammonium bicarbonate The flow of the solution maintains the pH of the reaction process at 6-6.5, the time for adding the materials is 60-90min, the temperature of the feeding process is maintained at 35-40°C, and the stirring speed is 250-350r/min. When the temperature is 50-60°C and maintain this temperature, add hydrogen peroxide and ammonium bicarbonate solution dropwise to maintain the pH at 6-6.5, continue the reaction for 10-30 minutes after the addition is complete, and then separate the solid and liquid to obtain the first filter residue and the first filtrate , the first filter residue is washed with hot pure water until the conductivity of the washing water is less than or equal to 100 μS/cm;

(3) Precipitation transformation, adding the first filter residue after washing in step (2) into a polyolefin hyperdispersant solution for slurrying, the mass ratio of the first filter residue to the polyolefin hyperdispersant solution is 1:5-10, After slurrying, heat up to a temperature of 40-50°C and keep the temperature constant, then add ammonia water to the slurry to maintain the pH of the dropwise addition process at 7.5-8.0, after the addition is complete, heat up to a temperature of 75-85°C, and stir for 30- After 40 minutes, solid-liquid separation is carried out to obtain a second filter residue and a second filtrate, and the second filter residue is added to hot pure water for washing. The conductivity of the washing water is ≤ 20 μS/cm;

(4) Drying the second filter residue after washing in step (3) with a disc dryer, then performing screening, iron removal and mixing to obtain small particles of nickel-cobalt-aluminum hydroxide.

The purity of the step (1) nickel-cobalt-aluminum salt is battery grade, the total number of moles of the finally obtained nickel-cobalt-aluminum mixed solution is 1.5-2mol/L, the concentration of ammonium bicarbonate is 0.5-0.6mol/L, phosphoric acid one The concentration of ammonium hydrogen is 1-1.2mol/L, and the precision filter adopts a ceramic filter element, and the pore size of the ceramic filter element is 20-100nm.

The concentration of ammonium monohydrogen phosphate in the bottom liquid in the step (2) is 0.1-0.12mol/L, adding ammonium bicarbonate solution simultaneously makes the pH of the bottom liquid be 6-6.5, and the volume of the bottom liquid is the mixed solution that adds, 1/15-1/12 of the total volume of the ammonium bicarbonate solution and the ammonium monohydrogen phosphate solution, the flow rate of the mixed solution and the ammonium monohydrogen phosphate solution are added to the bottom liquid at an even speed, and the total moles of nickel, cobalt, aluminum and phosphoric acid in the mixed solution are maintained. The molar ratio of ammonium hydrogen phosphate in the ammonium monohydrogen solution is 3:2.1-2.15, the mass fraction of the hydrogen peroxide added is 25-30%, and the molar number of hydrogen peroxide added is the total molar number of nickel-cobalt ions in the mother liquor after the feeding is completed. 2-2.5 times.

The temperature of the hot pure water used for washing the first filter residue in the step (2) is 70-75° C., the first filtrate is mixed with the washing water for washing the first filter residue, and then an acid solution is added to adjust the pH of the solution to 2-3 , and then add TBP for extraction, extract the phosphoric acid, add ammonia water to wash and recover to obtain ammonium phosphate, and the raffinate is concentrated, evaporated and crystallized to obtain ammonium salt.

In the step (3), the concentration of the polyolefin hyperdispersant solution is 0.01-0.02%, the stirring speed during slurrying is 300-350r/min, the slurrying time is 30-50min, and the concentration of ammonia water is 5-6mol/L , the total time for dropping ammonia water is 30-45min.

In the step (3), the second filtrate is mixed with the washing water for washing the second filter residue, and ammonia water is added to adjust the pH to 7.5-8. After precision filtration, the crystallization is concentrated to obtain ammonium monohydrogen phosphate, and the mixture is returned to obtain ammonium monohydrogen phosphate solution.

In the step (4), dry until the moisture content is lower than 0.5%. The sieve uses a 225-mesh sieve, and the iron removal uses an electromagnetic iron remover whose magnetic induction is 15000-25000 Gauss.

In the present invention, nickel-cobalt-aluminum phosphate precipitation is prepared first, and then ammonia water is added to convert the phosphate precipitation into hydroxide precipitation, thereby obtaining nickel-cobalt-aluminum hydroxide. When preparing the nickel-cobalt-aluminum precipitation, by controlling the reaction conditions , obtain the phosphate precipitation of nickel-cobalt-aluminum with small particle size and uniform distribution of nickel-cobalt-aluminum, and the index of the phosphate precipitation obtained is as follows:

index D10 D50 D90 BET Tap density value 0.5-0.7μm 1.5-1.8μm 2.3-2.5μm 8-12m ² /g 1.2-1.5g/mL

Then add ammonia water to carry out precipitation conversion, convert to hydroxide precipitation, and then process, the finally obtained small particle nickel cobalt aluminum hydroxide index is as follows:

index Ni+Co+Al P D10 D50 D90 value 60-61.5% 2000-2500ppm 0.4-0.6μm 1.2-1.5μm 2.0-2.3μm D100 Cd Mg Na mn Ca ＜5μm <10ppm <10ppm <10ppm <10ppm <10ppm K Zn Cu Ti Pb Si <10ppm <10ppm <10ppm <10ppm <10ppm <10ppm Tap density Sulfate Chloride BET pH appearance 1.4-1.6g/mL <20ppm <20ppm 5-8m ² /g 6-8 spherical

The nickel cobalt aluminum hydroxide obtained by the process is a green powder with good fluidity and a spherical shape.

In order to improve the recovery rate of cobalt and nickel, when phosphate precipitation is used, hydrogen peroxide is added for oxidation, and the unprecipitated nickel and cobalt ions can be further precipitated to increase the recovery rate of nickel and cobalt.

Finally, the converted mother liquor is precipitated, concentrated and crystallized to obtain ammonium monohydrogen phosphate for reuse, further reducing the cost.

The beneficial effect of the invention is that nickel-cobalt-aluminum hydroxide with a particle size of less than 2.5 microns can be obtained, with high sphericity and high tap density, phosphorus doping is realized, the process is simple, and energy consumption is low.

Detailed ways

The present invention will be described in detail below in conjunction with specific examples, a kind of preparation method of small particle nickel cobalt aluminum hydroxide of the present example, it is the following steps:

(1) Dosing, mix and dissolve nickel-cobalt-aluminum salt into pure water to obtain a nickel-cobalt-aluminum mixed solution, add acid and alkali solution to adjust the pH of the mixed solution to 1.0-1.2, and then remove iron through a fluid iron remover, and then pass through The precision filter is used for precision filtration, and then placed in a constant temperature tank to keep the temperature at 30-35°C; add ammonium bicarbonate to pure water to dissolve, then go through a fluid iron remover for iron removal, and then go through a precision filter for precision filtration. Then put it into a constant temperature tank to keep the temperature at 30-35°C; add ammonium monohydrogen phosphate to pure water to dissolve, then go through a fluid iron remover to remove iron, then pass through a precision filter for precision filtration, and then put it into a constant temperature tank Keep the internal temperature constant until the temperature is 30-35°C;

(2) reaction, the mixed solution that step (1) obtains, ammonium bicarbonate solution and ammonium hydrogen phosphate solution are added in the bottom liquid concurrently, the flow rate of stable mixed solution and the flow rate of ammonium hydrogen phosphate solution, adjust ammonium bicarbonate The flow of the solution maintains the pH of the reaction process at 6-6.5, the time for adding the materials is 60-90min, the temperature of the feeding process is maintained at 35-40°C, and the stirring speed is 250-350r/min. When the temperature is 50-60°C and maintain this temperature, add hydrogen peroxide and ammonium bicarbonate solution dropwise to maintain the pH at 6-6.5, continue the reaction for 10-30 minutes after the addition is complete, and then separate the solid and liquid to obtain the first filter residue and the first filtrate , the first filter residue is washed with hot pure water until the conductivity of the washing water is less than or equal to 100 μS/cm;

(3) Precipitation transformation, adding the first filter residue after washing in step (2) into a polyolefin hyperdispersant solution for slurrying, the mass ratio of the first filter residue to the polyolefin hyperdispersant solution is 1:5-10, After slurrying, heat up to a temperature of 40-50°C and keep the temperature constant, then add ammonia water to the slurry to maintain the pH of the dropwise addition process at 7.5-8.0, after the addition is complete, heat up to a temperature of 75-85°C, and stir for 30- After 40 minutes, solid-liquid separation is carried out to obtain a second filter residue and a second filtrate, and the second filter residue is added to hot pure water for washing. The conductivity of the washing water is ≤ 20 μS/cm;

(4) Drying the second filter residue after washing in step (3) with a disc dryer, then performing screening, iron removal and mixing to obtain small particles of nickel-cobalt-aluminum hydroxide.

The purity of the step (1) nickel-cobalt-aluminum salt is battery grade, the total number of moles of the finally obtained nickel-cobalt-aluminum mixed solution is 1.5-2mol/L, the concentration of ammonium bicarbonate is 0.5-0.6mol/L, phosphoric acid one The concentration of ammonium hydrogen is 1-1.2mol/L, and the precision filter adopts a ceramic filter element, and the pore size of the ceramic filter element is 20-100nm.

The concentration of ammonium monohydrogen phosphate in the bottom liquid in the step (2) is 0.1-0.12mol/L, adding ammonium bicarbonate solution simultaneously makes the pH of the bottom liquid be 6-6.5, and the volume of the bottom liquid is the mixed solution that adds, 1/15-1/12 of the total volume of ammonium bicarbonate solution and ammonium monohydrogen phosphate solution. The molar ratio of ammonium monohydrogen phosphate in the ammonium monohydrogen solution is 3:2.1-2.15, the mass fraction of the hydrogen peroxide added is 25-30%, and the hydrogen peroxide mole number added is the total mole number of nickel-cobalt ions in the mother liquor after the feeding is completed. 2-2.5 times.

The temperature of the hot pure water used for washing the first filter residue in the step (2) is 70-75° C., the first filtrate is mixed with the washing water for washing the first filter residue, and then an acid solution is added to adjust the pH of the solution to 2-3 , and then add TBP for extraction, extract the phosphoric acid, add ammonia water to wash and recover to obtain ammonium phosphate, and the raffinate is concentrated, evaporated and crystallized to obtain ammonium salt.

In the step (3), the concentration of the polyolefin hyperdispersant solution is 0.01-0.02%, the stirring speed during slurrying is 300-350r/min, the slurrying time is 30-50min, and the concentration of ammonia water is 5-6mol/L , the total time for dropping ammonia water is 30-45min.

In the step (3), the second filtrate is mixed with the washing water for washing the second filter residue, and ammonia water is added to adjust the pH to 7.5-8. After precision filtration, the crystallization is concentrated to obtain ammonium monohydrogen phosphate, and the mixture is returned to obtain ammonium monohydrogen phosphate solution.

In the step (4), dry until the moisture content is lower than 0.5%. The sieve uses a 225-mesh sieve, and the iron removal uses an electromagnetic iron remover whose magnetic induction is 15000-25000 Gauss.

The finally obtained small particle nickel cobalt aluminum hydroxide index is as follows:

index Ni+Co+Al P D10 D50 D90 value 60-61.5% 2000-2500ppm 0.4-0.6μm 1.2-1.5μm 2.0-2.3μm D100 Cd Mg Na mn Ca ＜5μm <10ppm <10ppm <10ppm <10ppm <10ppm K Zn Cu Ti Pb Si <10ppm <10ppm <10ppm <10ppm <10ppm <10ppm Tap density Sulfate Chloride BET pH appearance 1.4-1.6g/mL <20ppm <20ppm 5-8m ² /g 6-8 spherical

Example 1

A kind of preparation method of small particle nickel cobalt aluminum hydroxide, it is the following steps:

(1) Dosing, mix and dissolve the nickel-cobalt-aluminum salt into pure water to obtain a nickel-cobalt-aluminum mixed solution, add acid and alkali solution to adjust the pH of the mixed solution to 1.15, then remove iron through a fluid iron remover, and then pass through precision filtration Then put it into a constant temperature tank to keep the temperature at 31.5°C; add ammonium bicarbonate to pure water to dissolve, then go through a fluid iron remover to remove iron, then go through a precision filter for fine filtration, and then put it in Keep the temperature in the constant temperature tank to 31.5°C; add ammonium monohydrogen phosphate to pure water to dissolve, then go through the fluid iron remover to remove iron, then pass through the precision filter for precision filtration, and then put it in the constant temperature tank to keep the temperature at 31.5°C ℃;

(2) reaction, the mixed solution that step (1) obtains, ammonium bicarbonate solution and ammonium hydrogen phosphate solution are added in the bottom liquid concurrently, the flow rate of stable mixed solution and the flow rate of ammonium hydrogen phosphate solution, adjust ammonium bicarbonate The flow of the solution maintains the pH of the reaction process at 6.35, and the time for adding the materials is 80 minutes. During the feeding process, the temperature is maintained at 36°C, while the stirring speed is 315r/min. After adding the materials, the temperature is raised to 53°C and maintained at this temperature. temperature, add hydrogen peroxide and ammonium bicarbonate solution dropwise to maintain the pH at 6.35, continue to react for 20 minutes after the addition, and then separate the solid and liquid to obtain the first filter residue and the first filtrate. The first filter residue is washed with hot pure water until the washing water Conductivity≤100μS/cm;

(3) Precipitation transformation, the first filter residue after step (2) washing is added in the polyolefin hyperdispersant solution for slurrying, the mass ratio of the first filter residue and the polyolefin hyperdispersant solution is 1:8, slurrying After that, the temperature was raised to 45°C and kept at a constant temperature, and then ammonia water was added to the slurry to maintain the pH of the dropwise addition process at 7.8. After the addition was completed, the temperature was raised to 79°C, and after stirring for 35 minutes, solid-liquid separation was carried out to obtain the first The second filter residue and the second filtrate, the second filter residue is added to hot pure water for washing, and the conductivity of the washing water is ≤ 20 μS/cm;

(4) Drying the second filter residue after washing in step (3) with a disc dryer, then performing screening, iron removal and mixing to obtain small particles of nickel-cobalt-aluminum hydroxide.

The purity of said step (1) nickel-cobalt-aluminum salt is battery grade, the total number of moles of the nickel-cobalt-aluminum mixed solution finally obtained is 1.8mol/L, the concentration of ammonium bicarbonate is 0.54mol/L, and the concentration of ammonium monohydrogen phosphate The concentration is 1.12mol/L, and the precision filter adopts a ceramic filter element, and the pore size of the ceramic filter element is 80nm.

The concentration of ammonium monohydrogen phosphate in the bottom liquid in the described step (2) is 0.11mol/L, adding ammonium bicarbonate solution simultaneously makes the pH of bottom liquid be 6.35, and the volume of bottom liquid is the mixed solution that adds, ammonium bicarbonate solution and 1/14 of the total volume of the ammonium monohydrogen phosphate solution, the flow rate of the mixed solution and the ammonium monohydrogen phosphate solution are added to the bottom liquid at an even speed, and the total moles of nickel, cobalt, and aluminum in the mixed solution are kept equal to the monohydrogen phosphate in the ammonium monohydrogen phosphate solution. The molar ratio of ammonium is 3:2.12, the mass fraction of hydrogen peroxide added is 28%, and the molar number of hydrogen peroxide added is 2.15 times of the total molar number of nickel-cobalt ions in the mother liquor after the feeding is completed.

The temperature of the hot pure water used for washing the first filter residue in the step (2) is 72.5°C, mix the first filtrate with the washing water for washing the first filter residue, then add an acid solution to adjust the pH of the solution to 2.3, and then add TBP Perform extraction, extract phosphoric acid, add ammonia water to wash and recover to obtain ammonium phosphate, and the raffinate is concentrated, evaporated and crystallized to obtain ammonium salt.

In the step (3), the concentration of the polyolefin hyperdispersant solution is 0.013%, the stirring speed during slurrying is 320r/min, the slurrying time is 35min, and the ammonia concentration is 5.3mol/L. The time is 41 minutes.

In the step (3), the second filtrate is mixed with the washing water for washing the second filter residue, and ammonia water is added to adjust the pH to 7.8. After precision filtration, the crystallization is concentrated to obtain ammonium monohydrogen phosphate, and the mixture is returned to obtain an ammonium monohydrogen phosphate solution.

In the step (4), dry until the moisture content is lower than 0.5%. The sieve adopts a 225-mesh sieve, and the iron removal adopts an electromagnetic iron remover whose magnetic induction intensity is 20,000 Gauss.

The finally obtained small particle nickel cobalt aluminum hydroxide index is as follows:

index Ni+Co+Al P D10 D50 D90 value 60.5% 2230ppm 0.45μm 1.37μm 2.18μm D100 Cd Mg Na mn Ca 4.87μm 6ppm 7ppm 8ppm 5.1ppm 8.1ppm K Zn Cu Ti Pb Si 1.2ppm 2.8ppm 0.25ppm 5.6ppm 2.8ppm 8.7ppm Tap density Sulfate Chloride BET pH appearance 1.52g/mL 18.4ppm 5.9ppm 5.8m ² /g 6.8 spherical

Example 2

A kind of preparation method of small particle nickel cobalt aluminum hydroxide, it is the following steps:

(1) Dosing, mix and dissolve nickel-cobalt-aluminum salt into pure water to obtain a nickel-cobalt-aluminum mixed solution, add acid and alkali solution to adjust the pH of the mixed solution to 1.08, then remove iron through a fluid iron remover, and then pass through precision filtration Then put it into a constant temperature tank to keep the temperature at 33.8°C; add ammonium bicarbonate to pure water to dissolve, then go through a fluid iron remover to remove iron, then go through a precision filter for fine filtration, and then put it in Keep the temperature in the constant temperature tank to 33.8°C; add ammonium monohydrogen phosphate to pure water to dissolve, then go through the fluid iron remover to remove iron, then pass through the precision filter for precision filtration, and then put it in the constant temperature tank to keep the temperature at 33.8 ℃;

(2) reaction, the mixed solution that step (1) obtains, ammonium bicarbonate solution and ammonium hydrogen phosphate solution are added in the bottom liquid concurrently, the flow rate of stable mixed solution and the flow rate of ammonium hydrogen phosphate solution, adjust ammonium bicarbonate The flow of the solution maintains the pH of the reaction process at 6.15, and the time for adding the materials is 70 minutes. During the feeding process, the temperature is maintained at 38.5°C, while the stirring speed is 275r/min. After adding the materials, the temperature is raised to 52°C and maintained at this temperature. temperature, add hydrogen peroxide and ammonium bicarbonate solution dropwise to maintain the pH at 6.15, continue to react for 20 minutes after the addition is complete, and then separate the solid and liquid to obtain the first filter residue and the first filtrate. The first filter residue is washed with hot pure water until the washing water Conductivity≤100μS/cm;

(3) Precipitation transformation, the first filter residue after step (2) washing is added in the polyolefin hyperdispersant solution for slurrying, the mass ratio of the first filter residue and the polyolefin hyperdispersant solution is 1:9, slurrying After that, the temperature was raised to 43°C and kept at a constant temperature, and then ammonia water was added to the slurry to maintain the pH of the dropwise addition process at 7.9. After the addition was completed, the temperature was raised to 79°C, and after stirring for 33 minutes, solid-liquid separation was carried out to obtain the first The second filter residue and the second filtrate, the second filter residue is added to hot pure water for washing, and the conductivity of the washing water is ≤ 20 μS/cm;

(4) Drying the second filter residue after washing in step (3) with a disc dryer, then performing screening, iron removal and mixing to obtain small particles of nickel-cobalt-aluminum hydroxide.

The purity of said step (1) nickel-cobalt-aluminum salt is battery grade, the total number of moles of the nickel-cobalt-aluminum mixed solution finally obtained is 1.8mol/L, the concentration of ammonium bicarbonate is 0.55mol/L, and the concentration of ammonium monohydrogen phosphate The concentration is 1.15mol/L, and the precision filter adopts a ceramic filter element, and the pore size of the ceramic filter element is 40nm.

The concentration of ammonium monohydrogen phosphate in the bottom liquid in the described step (2) is 0.112mol/L, adding ammonium bicarbonate solution simultaneously makes the pH of bottom liquid be 6.15, and the volume of bottom liquid is the mixed solution that adds, ammonium bicarbonate solution and 1/13 of the total volume of the ammonium monohydrogen phosphate solution, the flow rate of the mixed solution and the ammonium monohydrogen phosphate solution are added to the bottom liquid at an even speed, and the total moles of nickel, cobalt and aluminum in the mixed solution are kept equal to the monohydrogen phosphate in the ammonium monohydrogen phosphate solution. The molar ratio of ammonium is 3:2.12, the mass fraction of hydrogen peroxide added is 27%, and the molar number of hydrogen peroxide added is 2.35 times of the total molar number of nickel-cobalt ions in the mother liquor after the feeding is completed.

The temperature of the hot pure water used for washing the first filter residue in the step (2) is 73.5°C, mix the first filtrate with the washing water for washing the first filter residue, then add an acid solution to adjust the pH of the solution to 2.15, and then add TBP Perform extraction, extract phosphoric acid, add ammonia water to wash and recover to obtain ammonium phosphate, and the raffinate is concentrated, evaporated and crystallized to obtain ammonium salt.

The concentration of the polyolefin hyperdispersant solution in the step (3) is 0.013%, the stirring speed during slurrying is 315r/min, the slurrying time is 45min, the ammoniacal liquor concentration is 5.5mol/L, and the total amount of ammoniacal liquor is added dropwise. The time is 41 minutes.

In the step (3), the second filtrate is mixed with the washing water for washing the second filter residue, and ammonia water is added to adjust the pH to 7.85. After precision filtration, the crystallization is concentrated to obtain ammonium monohydrogen phosphate, and the mixture is returned to obtain an ammonium monohydrogen phosphate solution.

In the step (4), dry until the moisture content is lower than 0.5%. The sieve adopts a 225-mesh sieve, and the iron removal adopts an electromagnetic iron remover whose magnetic induction intensity is 20,000 Gauss.

The finally obtained small particle nickel cobalt aluminum hydroxide index is as follows:

index Ni+Co+Al P D10 D50 D90 value 60.8% 2150ppm 0.47μm 1.39μm 2.17μm D100 Cd Mg Na mn Ca 4.68μm 3.2ppm 5.7ppm 2.9ppm 5.9ppm 6.8ppm K Zn Cu Ti Pb Si 5.9ppm 7.1ppm 6.7ppm 3.8ppm 1.8ppm 4.9ppm Tap density Sulfate Chloride BET pH appearance 1.51g/mL 13ppm 10.9ppm 6.8m ² /g 7.2 spherical

Example 3

A kind of preparation method of small particle nickel cobalt aluminum hydroxide, it is the following steps:

(1) Dosing, mix and dissolve nickel-cobalt-aluminum salt into pure water to obtain a nickel-cobalt-aluminum mixed solution, add acid and alkali solution to adjust the pH of the mixed solution to 1.13, then remove iron through a fluid iron remover, and then pass through precision filtration Then put it into a constant temperature tank to keep the temperature at 33.8°C; add ammonium bicarbonate to pure water to dissolve, then go through a fluid iron remover to remove iron, then go through a precision filter for fine filtration, and then put it in Keep the temperature in the constant temperature tank to 33.8°C; add ammonium monohydrogen phosphate to pure water to dissolve, then go through the fluid iron remover to remove iron, then pass through the precision filter for precision filtration, and then put it in the constant temperature tank to keep the temperature at 33.8 ℃;

(2) reaction, the mixed solution that step (1) obtains, ammonium bicarbonate solution and ammonium hydrogen phosphate solution are added in the bottom liquid concurrently, the flow rate of stable mixed solution and the flow rate of ammonium hydrogen phosphate solution, adjust ammonium bicarbonate The flow of the solution maintains the pH of the reaction process at 6.25, and the time for adding the materials is 80 minutes. During the feeding process, the temperature is maintained at 38°C, while the stirring speed is 335r/min. After adding the materials, the temperature is raised to 55°C and maintained at this temperature, add hydrogen peroxide and ammonium bicarbonate solution dropwise, and maintain the pH at 6.25, continue to react for 25 minutes after the addition, and then separate the solid and liquid to obtain the first filter residue and the first filtrate. The first filter residue is washed with hot pure water until the washing water Conductivity≤100μS/cm;

(3) Precipitation transformation, the first filter residue after step (2) washing is added in the polyolefin hyperdispersant solution for slurrying, the mass ratio of the first filter residue and the polyolefin hyperdispersant solution is 1:9, slurrying After that, the temperature was raised to 43°C and kept at a constant temperature, and then ammonia water was added to the slurry to maintain the pH of the dropwise addition process at 7.9. After the addition was completed, the temperature was raised to 79°C, and after stirring for 35 minutes, solid-liquid separation was carried out to obtain the first The second filter residue and the second filtrate, the second filter residue is added to hot pure water for washing, and the conductivity of the washing water is ≤ 20 μS/cm;

(4) Drying the second filter residue after washing in step (3) with a disc dryer, then performing screening, iron removal and mixing to obtain small particles of nickel-cobalt-aluminum hydroxide.

The purity of said step (1) nickel-cobalt-aluminum salt is battery grade, the total number of moles of the nickel-cobalt-aluminum mixed solution finally obtained is 1.85mol/L, the concentration of ammonium bicarbonate is 0.54mol/L, and the concentration of ammonium monohydrogen phosphate The concentration is 1.12mol/L, and the precision filter adopts a ceramic filter element, and the pore size of the ceramic filter element is 40nm.

The concentration of ammonium monohydrogen phosphate in the bottom liquid in the described step (2) is 0.11mol/L, adding ammonium bicarbonate solution simultaneously makes the pH of bottom liquid be 6.25, and the volume of bottom liquid is the mixed solution that adds, ammonium bicarbonate solution and 1/12 of the total volume of the ammonium monohydrogen phosphate solution, the flow rate of the mixed solution and the ammonium monohydrogen phosphate solution are added to the bottom liquid at an even speed, and the total moles of nickel, cobalt, and aluminum in the mixed solution are kept equal to the monohydrogen phosphate in the ammonium monohydrogen phosphate solution. The molar ratio of ammonium is 3:2.13, the mass fraction of hydrogen peroxide added is 29%, and the molar number of hydrogen peroxide added is 2.35 times of the total molar number of nickel-cobalt ions in the mother liquor after the feeding is completed.

The temperature of the hot pure water used for washing the first filter residue in the step (2) is 72° C., mix the first filtrate with the washing water for washing the first filter residue, then add an acid solution to adjust the pH of the solution to 2.5, and then add TBP Perform extraction, extract phosphoric acid, add ammonia water to wash and recover to obtain ammonium phosphate, and the raffinate is concentrated, evaporated and crystallized to obtain ammonium salt.

The concentration of the polyolefin hyperdispersant solution in the step (3) is 0.015%, the stirring speed during slurrying is 325r/min, the slurrying time is 40min, the ammoniacal liquor concentration is 5.3mol/L, and the total amount of ammoniacal liquor is added dropwise. The time is 42 minutes.

In the step (3), the second filtrate is mixed with the washing water for washing the second filter residue, and ammonia water is added to adjust the pH to 7.75. After precision filtration, the crystallization is concentrated to obtain ammonium monohydrogen phosphate, and the mixture is returned to obtain an ammonium monohydrogen phosphate solution.

In the step (4), dry until the moisture content is lower than 0.5%. The sieve adopts a 225-mesh sieve, and an electromagnetic iron remover is used for iron removal. The magnetic induction of the electromagnetic iron remover is 18,000 Gauss.

The finally obtained small particle nickel cobalt aluminum hydroxide index is as follows:

index Ni+Co+Al P D10 D50 D90 value 60.9% 2080ppm 0.51μm 1.38μm 2.09μm D100 Cd Mg Na mn Ca 4.18μm 3.8ppm 2.7ppm 6.9ppm 5.9ppm 2.9ppm K Zn Cu Ti Pb Si 2.9ppm 2.9ppm 0.9ppm 4.8ppm 2.9ppm 5.9ppm Tap density Sulfate Chloride BET pH appearance 1.57g/mL 12.9ppm 10.8ppm 6.8m ² /g 6.95 spherical

The product obtained in Examples 1, 2, and 3 is mixed with lithium carbonate and sintered, and the index of the positive electrode material of nickel-cobalt-aluminate lithium obtained is as follows

Dope the nickel-cobalt lithium aluminate with a particle size of 15-20 μm and mix them evenly:

It can be concluded that the small particle size lithium nickel cobalt aluminate prepared by the small particle size nickel cobalt aluminum hydroxide of this patent is doped with nickel cobalt lithium manganese oxide with a particle size of 15-20 μm, which can significantly improve the positive electrode material. compaction density.

Finally, it is noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be carried out Modifications or equivalent replacements without departing from the spirit and scope of the technical solution of the present invention shall be covered by the claims of the present invention.

Claims (7)

1. a kind of preparation method of little particle nickel cobalt aluminum hydroxide, which is characterized in that be following steps：

(1) match liquid, nickel cobalt aluminium mixed solution in nickel cobalt aluminium salt mixed dissolution to pure water, will be obtained, acid ＆ alkali liquid is added and adjusts mixing The pH of solution is 1.0-1.2, then carries out removing iron by fluid deferrization device, carries out secondary filter using accurate filter, so After to be put into thermostat constant temperature to temperature be 30-35 DEG C；Pure water dissolving is added in ammonium hydrogen carbonate, then passes through fluid deferrization device It carries out removing iron, secondary filter is carried out using accurate filter, it is 30-35 DEG C to be then placed in constant temperature to temperature in thermostat； Pure water dissolving is added in monoammonium phosphate, then carries out removing iron by fluid deferrization device, be carried out using accurate filter accurate Filtering, it is 30-35 DEG C to be then placed in constant temperature to temperature in thermostat；

(2) it reacts, mixed solution, ammonium bicarbonate soln and monoammonium phosphate solution cocurrent that step (1) obtains is added to bottom In liquid, stablize the flow of the flow and monoammonium phosphate solution of mixed solution, the flow for adjusting ammonium bicarbonate soln maintains reaction The pH of process is 6-6.5, and the time for adding material is 60-90min, and it is 35-40 DEG C that charging process, which maintains temperature, while stirring speed Degree is 250-350r/min, after adding material, is 50-60 DEG C and maintains this temperature with temperature is warming up to, be added dropwise hydrogen peroxide and Ammonium bicarbonate soln, maintenance pH are 6-6.5, the reaction was continued after addition 10-30min, are then separated by solid-liquid separation, obtain the first filter Hot pure water washing is added in slag and the first filtrate, the first filter residue, washs to the conductivity of washings≤100 μ S/cm；

(3) precipitation converts, pulp in the first filter residue addition polyolefins hyper-dispersant solution after step (2) is washed, and first The mass ratio of filter residue and polyolefins hyper-dispersant solution is 1:5-10, it is 40-50 DEG C of simultaneously constant temperature that temperature is warming up to after pulp, so Ammonium hydroxide is added toward pulp material afterwards, it is 7.5-8.0 to maintain the pH of dropwise addition process, and after addition, it is 75-85 DEG C to be warming up to temperature, It after being stirred to react 30-40min, is separated by solid-liquid separation, obtains the second filter residue and the second filtrate, the second filter residue addition hot pure water is washed The conductivity for washing washings is≤20 μ S/cm；

(4) it after the second filter residue after washing step (3) is dried using tray drier, sieved, remove iron and batch mixing, obtained Little particle nickel cobalt aluminum hydroxide.

2. a kind of preparation method of little particle nickel cobalt aluminum hydroxide according to claim 1, it is characterised in that：The step (1) nickel cobalt aluminium purity salt is LITHIUM BATTERY, and the total mole number of finally obtained nickel cobalt aluminium mixed solution is 1.5-2mol/L, carbonic acid A concentration of 0.5-0.6mol/L of hydrogen ammonium, a concentration of 1-1.2mol/L of monoammonium phosphate, accurate filter use ceramic element, The aperture of ceramic element is 20-100nm.

3. a kind of preparation method of little particle nickel cobalt aluminum hydroxide according to claim 1, it is characterised in that：The step (2) in midsole liquid monoammonium phosphate a concentration of 0.1-0.12mol/L, while ammonium bicarbonate soln is added and so that the pH of bottom liquid is The volume of 6-6.5, bottom liquid are the mixed solution being added, the 1/15-1/ of ammonium bicarbonate soln and monoammonium phosphate overall solution volume 12, the flow and monoammonium phosphate solution average rate of mixed solution are added in the liquid of bottom, maintain the nickel cobalt aluminium total moles of mixed solution The molar ratio of number and monoammonium phosphate in monoammonium phosphate solution is 3:The mass fraction of 2.1-2.15, the hydrogen peroxide of addition is 25-30%, the hydrogen peroxide molal quantity of addition are 2-2.5 times that charging finishes the total mole number of nickel cobalt ion in Mother liquor.

4. a kind of preparation method of little particle nickel cobalt aluminum hydroxide according to claim 1, it is characterised in that：The step (2) temperature for the hot pure water that the first residue washing uses in is 70-75 DEG C, by the washings of the first filtrate and the first filter residue of washing Mixing, it is 2-3 that acid solution, which is then added, and adjusts the pH of solution, and TBP is then added and is extracted, phosphoric acid extraction is come out, is added Ammonia scrubbing recycles to obtain ammonium phosphate, and raffinate crystallizes to obtain ammonium salt by concentration and evaporation.

5. a kind of preparation method of little particle nickel cobalt aluminum hydroxide according to claim 1, it is characterised in that：The step (3) a concentration of 0.01-0.02% of polyolefins hyper-dispersant solution in, mixing speed is 300-350r/min, slurry when pulp The change time is 30-50min, ammonia concn 5-6mol/L, and the total time for dripping ammonium hydroxide is 30-45min.

6. a kind of preparation method of little particle nickel cobalt aluminum hydroxide according to claim 1, it is characterised in that：The step (3) washings of the second filter residue of the second filtrate and washing are mixed, it is 7.5-8 that ammonium hydroxide, which is added, and adjusts pH, after secondary filter, Condensing crystallizing obtains monoammonium phosphate, returns and obtains monoammonium phosphate solution with liquid.

7. a kind of preparation method of little particle nickel cobalt aluminum hydroxide according to claim 1, it is characterised in that：The step (4) it is dried to moisture in and is less than 0.5%, screening is sieved using 225 mesh, except iron uses electric magnetic iron remover, electromagnetism to remove iron The magnetic induction intensity of device is 15000-25000 Gausses.