WO2024040908A1

WO2024040908A1 - Porous spherical ternary precursor and preparation method therefor, ternary positive electrode material, positive electrode plate and battery

Info

Publication number: WO2024040908A1
Application number: PCT/CN2023/079086
Authority: WO
Inventors: 蒋伟; 刘更好; 李伟权; 阮丁山; 李和敏; 李长东
Original assignee: 广东邦普循环科技有限公司; 湖南邦普循环科技有限公司
Priority date: 2022-08-25
Filing date: 2023-03-01
Publication date: 2024-02-29
Also published as: FR3139242A1; CN115403076A

Abstract

The present invention relates to the technical field of batteries, and disclosed are a porous spherical ternary precursor and a preparation method therefor, a ternary positive electrode material, a positive electrode plate and a battery. The method comprises: introducing a metal solution, ammonia water and an alkali liquor into a reaction kettle together, starting stirring, maintaining the pH at 11.5-12.5, and granulating the mixture to form primary particles; continuing granulation so as to agglomerate the primary particles to form secondary particles, gradually reducing the pH in the reaction kettle to 11-11.5 during the process that the secondary particles grow to a target particle size, synchronously and gradually reducing the stirring speed so as to gradually grow the secondary particles to form porous spheres, and after the secondary particles grow to the target particle size, rapidly increasing the pH in the reaction kettle to 11.5-12.5 and maintaining same for a preset time to obtain an intermediate precursor; and treating the intermediate precursor to obtain a porous spherical ternary precursor. The method can achieve organic unification of large specific surface area and high compaction of the precursor on the premise of ensuring the cycling performance of a battery.

Description

A porous spherical ternary precursor and its preparation method, ternary cathode material, cathode plate and battery

Technical field

The present invention relates to the field of battery technology, and specifically, to a porous spherical ternary precursor and a preparation method thereof, a ternary positive electrode material, a positive electrode sheet and a battery.

Background technique

With the rapid development of the world economy, non-renewable fossil energy is increasingly consumed, and there is an urgent need to find emerging and alternative new energy sources to open up a new path for sustainable development. In recent years, the automobile industry, which is dominated by new energy sources, has risen rapidly. Lithium-ion batteries are deeply loved and paid attention to by people due to their advantages such as high energy density, green and clean, easy to carry, and reusable. Among them, nickel-cobalt-manganese ternary materials are the most widely used as cathode materials for lithium-ion batteries. By the end of last year, they had occupied the largest share of the installed volume of cathode materials for lithium-ion batteries.

Ternary materials have become a hot research topic, in which ternary precursors play an important role. The cathode material almost completely inherits all the physical and chemical indicators of the precursor. Various parameters of the precursor, such as specific surface area, tap density, particle size distribution, etc., directly affect the electrochemical performance of the battery. A larger specific surface area can greatly increase the contact area between the material and the electrolyte, and a higher tap density can maintain The cycle stability of the battery and the improvement of volumetric energy density.

However, the specific surface area and tapping are two important parameters of the ternary precursor, and the two are often in opposition. That is, the primary particles of the highly tapped precursor are relatively tight and it is difficult to obtain a higher specific surface area. The primary particles with a high specific surface area are relatively small. Loose and difficult to have high vibration.

In view of this, the present invention is proposed.

Contents of the invention

The purpose of the present invention is to provide a porous spherical ternary precursor and a preparation method thereof, which can realize the organic unity of large specific surface area and high vibration while ensuring the cycle performance of the battery, and significantly improve the electrochemical performance of the battery.

The present invention also aims to provide a ternary positive electrode material, a positive electrode sheet and a battery, all of which are prepared by the above-mentioned porous spherical ternary precursor.

The scheme of the present invention is recorded as follows:

In a first aspect, the present invention provides a method for preparing a porous spherical ternary precursor, including:

Pour the metal solution, ammonia water and alkali solution obtained by mixing the nickel salt, cobalt salt and manganese salt into a reaction kettle with a reaction bottom liquid of pH 11.5-12.5, start stirring and maintain the pH in the reaction kettle at 11.5-12.5. 12.5 Perform granulation to form primary particles;

Continue granulation to agglomerate the primary particles to form secondary particles. During the process of the secondary particles growing to the target particle size, gradually reduce the pH in the reaction kettle to 11-11.5, and gradually reduce the stirring speed simultaneously so that the secondary particles grow to the target particle size. The particles gradually grow into porous spherical shapes, and after the secondary particles grow to the target particle size, the pH in the reaction kettle is quickly raised to 11.5-12.5 and maintained for a preset time to obtain the intermediate precursor;

The intermediate precursor is post-processed to obtain a porous spherical ternary precursor.

In an optional embodiment, the target particle size of the secondary particles is 10.1<D50≤10.5μm;

Preferably, during the formation of secondary particles, the steps of gradually reducing the pH in the reaction kettle to 11-11.5 and simultaneously gradually reducing the stirring speed include:

When the D50 of the secondary particles is ≤3.5μm, the pH should be adjusted to 11.5-12.5 and the stirring speed should be adjusted to 450-550rpm. When the secondary particles are 3.5<D50≤7.5μm, the pH should be adjusted to 11.5-11.8 and the stirring speed should be adjusted to 450-550rpm. The speed should be adjusted to 300-450rpm; when the secondary particles are 7.5<D50≤10.1μm, the pH should be adjusted to 11-11.5, and the stirring speed should be adjusted to 250-300rpm.

In an optional embodiment, before the metal solution is mixed with the alkali solution, it also includes adding an M-containing compound to the metal solution;

Preferably, the M-containing compound is one of molybdenum trioxide, tungsten trioxide, and zirconium sulfate;

Preferably, 610-700g of M-containing compound needs to be added to every 800-900L of metal solution.

In an optional embodiment, the general chemical formula of the porous spherical ternary precursor is Ni _x Co _y Mn _z M _w (OH) ₂ , where 0.92≤x≤0.97; 0.02≤y≤0.06; 0.01≤z≤ 0.02; 0.001≤w≤0.02; x+y+z+w=1;

Preferably, the specific surface area of the porous spherical ternary precursor is 13-15m ² /g;

Preferably, the tap density of the porous spherical ternary precursor is 2.05-2.30g/cm ³ ;

Preferably, the sulfur content of the porous spherical ternary precursor is 1500-1800ppm;

Preferably, the nickel salt is any one of nickel sulfate hexahydrate and nickel chloride;

Preferably, the cobalt salt is any one of cobalt sulfate heptahydrate and cobalt chloride;

Preferably, the manganese salt is manganese sulfate monohydrate.

In an optional embodiment, the flow rate of the metal solution into the reaction kettle is 20-40L/h; the flow rate of the alkali solution into the reaction kettle is 8-18L/h.

In an optional embodiment, the concentration of the metal solution is 1.6-2.2 mol/L.

In an optional embodiment, the ammonia concentration is 1.8-3.2g/L.

In an optional embodiment, the alkali solution is sodium hydroxide solution; preferably, the concentration of the sodium hydroxide solution is 6-12 mol/L.

In an optional embodiment, the stirring speed for forming primary particles is maintained at 450-550 rpm.

In an optional embodiment, the nucleation reaction time to form primary particles is 3-7 hours.

In an optional implementation, the preset time is 10-40 minutes.

In an optional embodiment, the reaction bottom liquid is obtained by adding ammonia water while stirring in heated clear water;

Preferably, the heating temperature range of clean water is 55-75°C;

Preferably, the stirring speed is maintained at 450-550 rpm.

In a second aspect, the present invention provides a porous spherical ternary precursor, which is prepared by the method for preparing a porous spherical ternary precursor in any one of the preceding embodiments.

In a third aspect, the present invention provides a ternary cathode material, including a porous spherical ternary precursor prepared by the method for preparing a porous spherical ternary precursor in any one of the preceding embodiments; or, comprising a porous spherical ternary precursor according to the preceding embodiment. Spherical ternary precursor.

In a fourth aspect, the present invention provides a positive electrode sheet, including the positive electrode material of the aforementioned embodiment.

In a fifth aspect, the present invention provides a battery including the positive electrode sheet of the aforementioned embodiment.

The present invention at least has the following advantages or beneficial effects:

The invention provides a method for preparing a porous spherical ternary precursor. In the process of secondary particles growing to the target particle size, the pH in the reaction kettle is gradually reduced to 11-11.5, and the stirring speed is gradually reduced simultaneously. In order to make the secondary particles gradually grow into porous spherical shapes, and after the secondary particles grow to the target particle size, the pH in the reaction kettle is rapidly raised to 11.5-12.5 and maintained for a preset time to obtain the intermediate precursor; The intermediate precursor is post-processed to obtain a porous spherical ternary precursor.

The beneficial effects of this method include the following:

(1) This method can ensure that the primary particles are uniform in thickness and roughly in the shape of a short and thin "toothpick sphere", which is not only conducive to ensuring the formation of a porous structure during the formation of secondary particles to ensure the specific surface area of the entire precursor, but also is beneficial to Ensure tap density to improve the electrochemical performance of the battery;

(2) This method can ensure that the particles agglomerate and grow to the target particle size, and can suppress the generation of small particles, so that the shape and structure of the particles with the target particle size are stable porous spherical shapes, so as to ensure the cycle performance of the battery. At the same time, it achieves the organic unity of large specific surface area and high vibration;

(3) This method can not only ensure the stability of the secondary particle morphology and structure, reduce the breakage and cracking of the secondary particles to ensure the electrochemical performance of the battery, but also increase the particle size distribution of the entire secondary particles so that each size The particle size distribution is more uniform to ensure the uniformity and stability of the secondary particle structure and morphology of the porous spherical structure, so as to further achieve the organic unity of large specific surface area and high vibration while ensuring the cycle performance of the battery;

(4) This method can reduce the sulfur content in the precursor, making the sulfur removal operation simpler and more convenient, thereby reducing the cost of sulfur removal.

In summary, the preparation method of the porous spherical ternary precursor provided by the embodiments of the present invention can ensure the cycleability of the battery. Under the premise of high energy efficiency, the organic unity of large specific surface area and high vibration is achieved to fully improve the electrochemical performance of the battery.

Embodiments of the present invention also provide a ternary positive electrode material, a positive electrode sheet and a battery, all of which are prepared by the above-mentioned porous spherical ternary precursor. Therefore, it also has the advantage of improving the electrochemical performance of the battery.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and therefore do not It should be regarded as a limitation of the scope. For those of ordinary skill in the art, other relevant drawings can also be obtained based on these drawings without exerting creative efforts.

Figure 1 is an SEM morphology image of a porous spherical ternary precursor provided by an embodiment of the present invention;

Figure 2 is a slice morphology diagram of a porous spherical ternary precursor provided by an embodiment of the present invention.

Detailed ways

In order to make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the examples, the conditions should be carried out according to the conventional conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not indicated, they are all conventional products that can be purchased commercially.

The features and performance of the present invention will be described in further detail below with reference to examples.

Figure 1 is an SEM morphology diagram of a porous spherical ternary precursor provided by an embodiment of the present invention; Figure 2 is a slice morphology diagram of a porous spherical ternary precursor provided by an embodiment of the present invention. Referring to Figures 1 and 2, embodiments of the present invention provide a porous spherical ternary precursor, which is prepared by the following method:

S1: Pour the metal solution, ammonia water and alkali solution obtained by mixing the nickel salt, cobalt salt and manganese salt into the reaction kettle with the reaction bottom liquid with a pH of 11.5-12.5, start stirring and maintain the pH in the reaction kettle at 11.5-12.5 Perform granulation to form primary granules;

S2: Continue granulation to agglomerate the primary particles to form secondary particles. During the process of the secondary particles growing to the target particle size, gradually reduce the pH in the reaction kettle to 11-11.5, and simultaneously gradually reduce the stirring speed so that The secondary particles gradually grow into porous spherical shapes, and after the secondary particles grow to the target particle size, the pH in the reactor is rapidly raised to 11.5-12.5 and maintained for a preset time to obtain the intermediate precursor;

S3: Post-process the intermediate precursor to obtain a porous spherical ternary precursor.

Specifically, in step S1, during the process of granulating to form primary particles, the pH is controlled between 11.5 and 12.5, so that the thickness and shape of the primary particles formed by granulation are relatively uniform and roughly appear "thin and short""Toothpick spherical shape" is also similar to a short and thin ellipsoid, which can ensure the formation of porous morphology through the spherical structure during the secondary particle agglomeration process to ensure the specific surface area, and can also ensure the tap density through the thin and short structure, so as to simultaneously Increase the specific surface area and tap density of particles in the medium particle stage. Moreover, during this process, if the pH is lower than 11.5, small particles will agglomerate, which is not conducive to To ensure the morphological stability of the "toothpick spherical shape", if the pH is higher than 12.5, the primary particle size will be too small, so that the thickness and shape of the particles cannot meet the needs of granulation.

In step S2, by gradually reducing the pH during the formation of secondary particles by controlling the pH, the pH can be gradually reduced from 11.5-12.5 to 11-11.5, which can ensure that the particles can agglomerate and grow to the target particle size, and can suppress small particles. Particle generation makes the shape and structure of the particles of the target particle size into a stable porous spherical shape, so as to achieve the organic unity of large specific surface area and high vibration while ensuring the cycle performance of the battery; at the same time, the formation of secondary particles is gradually reduced through control The stirring rate during the process can further ensure the stability of the secondary particle morphology and structure, reduce the breakage and cracking of the secondary particles, and ensure the electrochemical performance of the battery.

In addition, by rapidly increasing the pH after the secondary particles grow to the target particle size, the particle size of the secondary particles can be controlled to maintain the particle size of the secondary particles at the target particle size, and small particles can be formed by increasing the pH. The particle structure is used to increase the particle size distribution of the entire secondary particles and make the particle size distribution of each size more uniform to ensure the uniformity and stability of the secondary particle structure and morphology of the porous spherical structure to further ensure the cycle of the battery. While achieving high performance, it achieves the organic unity of large specific surface area and high vibration. Moreover, during the growth process of the secondary particles, a more regular spherical structure is formed through control, so that during the battery charge and discharge process, the electrolyte infiltrates the various positions of the electrode piece prepared from the precursor more regularly and uniformly, reducing the charge and discharge process. The generation of side reactions ensures the cycle performance of the battery and extends the service life of the battery. In addition, by rapidly increasing the pH, the sulfur content in the precursor can be reduced accordingly, making the sulfur removal operation simpler and more convenient, thereby reducing the cost of sulfur removal.

In step S3, post-processing includes centrifugation, drying, batch mixing, sieving and demagnetization in sequence to ensure that the porous spherical ternary precursor can be used to prepare cathode materials, cathode pole sheets and batteries.

In summary, the preparation method of the porous spherical ternary precursor provided by the embodiments of the present invention can realize the organic unity of large specific surface area and high vibration on the premise of ensuring the cycle performance of the battery, so as to fully improve the electrochemical performance of the battery. Moreover, the specific surface area of the porous spherical ternary precursor can be increased to ^13-15m2 /g, and the tap density of the porous spherical ternary precursor can be increased to 2.05-2.30g/ ^cm3 ; the content of the porous spherical ternary precursor can be increased to 13-15m2/g. The sulfur content can be reduced to 1500-1800ppm.

As an optional solution, in the embodiment of the present invention, in step S1, the alkali solution is a sodium hydroxide solution, and before the metal solution and the alkali solution are mixed, the compound containing M is mixed with the metal solution. The M-containing compound is one of molybdenum trioxide, tungsten trioxide, and zirconium sulfate. By mixing M-containing compounds in the metal solution, metal elements (molybdenum, tungsten, zirconium) can be doped during the synthesis stage of the precursor. For example, each 800-900L of metal solution usually requires 610-700g of M-containing compound. Doping a specific proportion of metal elements in this step will not affect the formation and stability of the porous spherical structure, but can also further increase the capacity of the cathode material when it is sintered into the cathode material to further improve the electrochemistry of the battery. performance. Based on doping with M-containing compounds, the general chemical formula of the porous spherical ternary precursor provided by the embodiment of the present invention is Ni _x Co _y Mn _z M _w (OH) ₂ , where 0.92≤x≤0.97; 0.02≤ y≤0.06; 0.01≤z≤0.02; 0.001≤w≤0.02; x+y+z+w=1. The nickel salt can be selected from nickel sulfate hexahydrate or nickel chloride; the cobalt salt can be selected from cobalt sulfate heptahydrate or cobalt chloride; and the manganese salt can be manganese sulfate monohydrate. The usage ratio of nickel salt, cobalt salt and manganese salt is roughly (94-98):(1-3):(1-3). For example, 97:2:1 can be selected.

Further optionally, in the embodiment of the present invention, in step S1, the concentration of the metal solution is 1.6-2.2mol/L; the concentration of ammonia solution is 1.8-3.2g/L; and the concentration of the sodium hydroxide solution is 6-12mol /L. By controlling the concentration of each component of the mixed solution, the corresponding pH value can be matched to prepare a thin and short "toothpick sphere", which is also similar to a short and ellipsoid-shaped primary particle, so that the secondary particles can be reunited. During the process, the formation of porous morphology is ensured through the spherical structure to ensure the specific surface area, and the tap density can also be ensured through the thin and short structure to simultaneously increase the specific surface area and tap density of the particles in the medium particle stage.

At the same time, in the embodiment of the present invention, the flow rate of the metal solution into the reaction kettle is 20-40L/h; the flow rate of the alkali solution into the reaction kettle is 8-18L/h. During the primary granulation process, the pH can be maintained in a stable range by controlling the flow rate of the metal solution and the flow rate of the alkali solution, which can assist the formation of short and thin "toothpick spherical" primary particles to ensure the formation of medium-sized particles. Specific surface area and tap density to fully improve the electrochemical performance of the battery.

Furthermore, in step S1, the reaction bottom liquid is obtained by adding ammonia water while stirring in the heated clear water, and the heating temperature range of the clear water is 55-75°C. The stirring speed is maintained at 450-550rpm. Before adding ammonia, clean water needs to be submerged up to the pH probe to ensure the accuracy of the pH test. At the same time, the temperature and stirring speed of the clean water need to be maintained during the entire primary particle formation process, and the nucleation reaction time to form primary particles is 3-7 hours. By controlling the nucleation time, the shape and size of the primary particles can be ensured, so that the tap density and specific surface area of the prepared precursor can be fully guaranteed by forming "toothpick spherical" primary particles.

Similarly, in the embodiment of the present invention, in step S2, the target particle size of the secondary particles is 10.1<D50≤10.5 μm. Controlling the target particle size of the secondary particles within this range will, on the one hand, facilitate the formation of a porous spherical structure, and on the other hand, avoid the problem of performance degradation caused by excessively large secondary particle sizes. At the same time, the pH during the growth of secondary particles is related to the particle size of the particles. Specifically, during the formation of secondary particles, the pH in the reaction kettle is gradually reduced to 11-11.5, and the stirring is gradually reduced simultaneously. The speed steps include: when the D50 of the secondary particles ≤ 3.5 μm, the pH is adjusted to 11.5-12.5, and the stirring speed is adjusted to 450-550 rpm; when the secondary particles are 3.5 < D50 ≤ 7.5 μm, the pH is adjusted to 11.5-11.8, the stirring speed is adjusted to 300-450rpm; when the secondary particles are 7.5<D50≤10.1μm, the pH is adjusted to 11-11.5, and the stirring speed is adjusted to 250-300rpm.

On the one hand, the smaller the particle size of the secondary particles, the higher the corresponding pH, so that the secondary particles can grow to ensure the formation of secondary particles with the target particle size; on the other hand, as the particle size of the secondary particles increases, As the pH increases, the pH gradually decreases, and the stirring speed is lowered accordingly, which can inhibit the formation of small particles in the growing process of secondary particles, allowing the particles to agglomerate and grow to form a more regular porous spherical structure that reaches the target particle size. In order to fully ensure the tap density and specific surface area of the precursor, ensure The electrochemical performance of the battery.

Embodiments of the present invention also provide a ternary cathode material, which is prepared by the above-mentioned porous spherical ternary precursor. Therefore, the ternary cathode material can also improve the electrochemical performance of the battery, ensure the cycle performance of the battery, and save the manufacturing cost of the battery.

In detail, the ternary cathode material is obtained by mixing the above-mentioned porous spherical ternary precursor and a lithium source and then sintering. The proportion of lithium source is less than 5%, and the lithium source can be selected from raw materials that can provide lithium ions, such as lithium carbonate or lithium hydroxide.

An embodiment of the present invention also provides a positive electrode sheet, which is prepared from the above-mentioned positive electrode material. Wherein, the positive electrode sheet may include a current collector and a positive active material layer disposed on at least one side of the current collector. The cathode active material layer is obtained by coating the cathode slurry on the current collector, drying and cold pressing. The positive electrode slurry includes positive electrode materials, conductive agents, binders and solvents. Among them, the current collector can be aluminum foil, and the conductive agent and binder each account for less than 5%. The conductive agent can be carbon black, carbon nanotubes, graphene, etc., and the binder can be polyvinylidene fluoride. (PVDF), the solvent can be N-methylpyrrolidone (NMP).

Because the above-mentioned positive electrode piece is prepared from a porous spherical ternary precursor. Therefore, the positive electrode plate can also improve the electrochemical performance of the battery, ensure the cycle performance of the battery, and save the manufacturing cost of the battery.

An embodiment of the present invention also provides a battery, including the positive electrode sheet of the aforementioned embodiment. Moreover, the battery specifically includes a casing, a positive electrode piece, a separator, a negative electrode piece, and an electrolyte. Among them, the positive electrode sheet, the separator and the negative electrode sheet are stacked, and a bare battery core is formed by lamination or winding. After the bare battery core is installed in the case and the electrolyte is injected, the battery can be obtained. The negative electrode sheet may include a current collector and a negative active material layer. The current collector may be copper foil. The negative active material layer is obtained by coating the current collector with negative active slurry, drying and cold pressing. Among them, the negative electrode active slurry includes negative electrode materials, conductive agents, binders and solvents. The amount of conductive agent and binder is less than 5%, and the negative electrode material can be selected from soft carbon, hard carbon or composite carbon, etc. The conductive agent can be selected from conductive carbon black, conductive graphite, vapor-phase grown carbon fiber, carbon nanotubes, etc. The binder can be styrene-butadiene rubber, and the solvent can be N-methylpyrrolidone (NMP).

Because the above battery is prepared from a porous spherical ternary precursor. Therefore, the battery also has the advantages of high electrochemical performance, good cycle performance, and low manufacturing cost.

The preparation process and properties of the above porous spherical ternary precursor will be described in detail below with reference to specific examples and comparative examples:

Example 1

This embodiment provides a battery, which is prepared by the following method:

S1: Preparation of positive electrode plate, step S1 specifically includes:

S11: Preparation of porous spherical ternary precursor:

Step S11 specifically includes Sa: input clean water into the reaction kettle, and ensure that the clean water can submerge the pH probe, and the reaction kettle rises Warm to 60°C, start stirring and maintain 500rpm, add ammonia water with a concentration of 2.3g/L, adjust the pH to 12, and obtain the reaction bottom liquid;

Sb: Mix nickel sulfate hexahydrate, cobalt sulfate heptahydrate, and manganese sulfate monohydrate in a ratio of 97:2:1 to form a metal solution with a total concentration of 2mol/L. Add 650g of zirconium sulfate to every 850L of metal solution. , Ammonia water with a concentration of 6-12mol/L and sodium hydroxide solution with a concentration of 6-12mol/L are introduced together through a metering pump according to the flow rate of metal solution 25L/h, sodium hydroxide solution 9L/h, and ammonia water 1.5L/h. In the reaction kettle, after the liquid is added, the pH of the original reaction bottom liquid is maintained at 12, and the nucleation reaction takes 3-7 hours. The particles grow up, and the prepared polycrystalline particles overflow into the aging tank;

Sc: Slowly lower the pH and stir as the secondary particles grow. When D50≤3.5, pH is 12, stir: 500rpm. When 3.5<D50≤7.5, pH: 11.8, stir: 400rpm. When 7.5<D50≤ 10.5, pH: 11.5, stirring: 280rpm; target particle size: 10.1-10.5μm, to reach the target particle size D50 and grow to 10.3μm, increase the pH to 12.5, and maintain it for 30 minutes, then adjust to the original pH, repeat the operation, centrifuge, After drying, batch mixing, sieving and demagnetization, the ultra-high nickel ternary precursor Ni _0.9685 Co _0.02 Mn _0.01 M _0.0015 (OH) ₂ was obtained.

S12: Preparation of cathode materials:

The ultra-high nickel ternary precursor and lithium hydroxide are mixed in a ratio of 93:2 and sintered to obtain a ternary cathode material.

S13: Preparation of pole pieces:

Mix the ternary positive electrode material, acetylene black, and polyvinylidene fluoride (PVDF) according to 93:3:2, add NMP and stir to obtain a positive electrode slurry. The positive electrode slurry is coated on both side surfaces of the aluminum foil, dried and cold pressed to obtain the positive electrode sheet.

S2: Preparation of negative electrode sheet:

Mix hard carbon, acetylene black, and styrene-butadiene rubber in a ratio of 93:3:2, add NMP and stir to make a negative electrode slurry; apply the negative electrode slurry on the copper foil current collector, and bake it After drying and cold pressing, the negative electrode piece is obtained.

S3: Preparation of batteries:

After the composite positive electrode piece, separator and negative electrode piece are arranged in sequence, and the sheets are stacked to prepare a bare cell, the bare cell is installed into the case and the electrolyte is injected; the battery after the liquid injection is allowed to stand, precharged, After exhaust gas is extracted, sealed, and divided into volumes, a lithium-ion battery is prepared.

Example 2

This embodiment provides a battery, and the difference between its preparation method and the preparation method of Embodiment 1 is that step S11 specifically includes:

Sa: Input clean water into the reaction kettle, and ensure that the clean water can submerge the pH probe. Heat the reaction kettle to 60°C, start stirring and maintain 480rpm, add ammonia water with a concentration of 3g/L, adjust the pH to 12.5, and obtain the reaction bottom liquid;

Sb: Mix nickel sulfate hexahydrate, cobalt sulfate heptahydrate, and manganese sulfate monohydrate in a ratio of 97:2:1 to a total concentration of 2mol/L To prepare a metal solution, add 610g of zirconium sulfate to every 800L of metal solution, and add 150g of zirconium sulfate to the sodium hydroxide solution to form an alkali solution. Mix the metal solution, ammonia with a concentration of 6-12mol/L and ammonia with a concentration of 6-12mol/L. The sodium hydroxide solution is passed into the reaction kettle through a metering pump at a flow rate of 25L/h of metal solution, 9L/h of sodium hydroxide solution, and 1.5L/h of ammonia water. After the liquid is introduced, the pH of the original reaction bottom liquid is maintained at 12, resulting in The nuclear reaction lasts for 3-7 hours, the particles grow up, and the prepared polycrystalline particles overflow into the aging tank;

Sc: Slowly lower the pH and stir as the secondary particles grow. When D50≤3.5, pH is 12.0, stirring: 480rpm. When 3.5<D50≤7.5, pH: 11.7, stirring: 450rpm. When 7.5<D50≤ 10.5, pH: 11.4, stirring: 260rpm; target particle size: 10.1-10.5μm, to reach the target particle size D50 and grow to 10.3μm, increase the pH to 12.5, and maintain it for 30 minutes, then adjust to the original pH, repeat the operation, centrifuge, After drying, batch mixing, sieving and demagnetization, the ultra-high nickel ternary precursor Ni _0.9685 Co _0.02 Mn _0.01 M _0.0015 (OH) ₂ was obtained.

Example 3

Sa: Input clean water into the reaction kettle, and ensure that the clean water can submerge the pH probe. Heat the reaction kettle to 60°C, start stirring and maintain 460rpm, add ammonia water with a concentration of 1.8g/L, adjust the pH to 11.5, and obtain the reaction bottom liquid;

Sb: Mix nickel sulfate hexahydrate, cobalt sulfate heptahydrate, and manganese sulfate monohydrate in a ratio of 97:2:1 to form a metal solution with a total concentration of 2mol/L. Add 640g of zirconium sulfate to every 880L of metal solution. , ammonia water with a concentration of 8mol/L and sodium hydroxide solution with a concentration of 10mol/L are passed into the reaction kettle through a metering pump according to the flow rate of metal solution 25L/h, sodium hydroxide solution 9L/h, and ammonia water 1.5L/h. After entering the liquid, maintain the pH of the original reaction bottom liquid at 12, nucleate for 3-7 hours, the particles will grow up, and the prepared polycrystalline particles will overflow into the aging tank;

Sc: Slowly lower the pH and stir as the secondary particles grow. When D50≤3.5, the pH is 11.7, stirring: 460rpm. When 3.5<D50≤7.5, pH: 11.5, stirring: 350rpm. When 7.5<D50≤ 10.5, pH: 11.2, stirring: 270rpm; target particle size: 10.1-10.5μm, to reach the target particle size D50 and grow to 10.3μm, increase the pH to 12.5, and keep it for 30 minutes, then adjust to the original pH, repeat the operation, centrifuge, After drying, batch mixing, sieving and demagnetization, the ultra-high nickel ternary precursor Ni _0.9685 Co _0.02 Mn _0.01 M _0.0015 (OH) ₂ was obtained.

Example 4

Sa: Input clean water into the reaction kettle and ensure that the water can submerge the pH probe. Heat the reaction kettle to 60°C and start stirring. Keep stirring at 550rpm, add ammonia water with a concentration of 4g/L, adjust the pH to 13, and obtain the reaction bottom liquid;

Sb: Mix nickel sulfate hexahydrate, cobalt sulfate heptahydrate, and manganese sulfate monohydrate in a ratio of 97:2:1 to form a metal solution with a total concentration of 2mol/L. Add 700g of zirconium sulfate to every 900L of metal solution. , ammonia water with a concentration of 10mol/L and sodium hydroxide solution with a concentration of 12mol/L are passed into the reaction kettle through a metering pump according to the flow rate of metal solution 25L/h, sodium hydroxide solution 9L/h, and ammonia water 1.5L/h. After entering the liquid, maintain the pH of the original reaction bottom liquid at 12, nucleate for 3-7 hours, the particles will grow up, and the prepared polycrystalline particles will overflow into the aging tank;

Sc: Slowly lower the pH and stir as the secondary particles grow. When D50≤3.5, pH is 12.5, stir: 550rpm. When 3.5<D50≤7.5, pH: 11.8, stir: 450rpm. When 7.5<D50≤ 10.5, pH: 11.5, stirring: 300rpm; target particle size: 10.1-10.5μm, to reach the target particle size D50 and grow to 10.3μm, increase the pH to 12.8, and maintain it for 30 minutes, then adjust to the original pH, repeat the operation, centrifuge, After drying, batch mixing, sieving and demagnetization, the ultra-high nickel ternary precursor Ni _0.9685 Co _0.02 Mn _0.01 M _0.0015 (OH) ₂ was obtained.

Example 5

Sa: Input clean water into the reaction kettle, and ensure that the clean water can submerge the pH probe. Heat the reaction kettle to 60°C, start stirring and maintain 500rpm, add ammonia water with a concentration of 3g/L, adjust the pH to 12.5, and obtain the reaction bottom liquid;

Sb: Mix nickel sulfate hexahydrate, cobalt sulfate heptahydrate, and manganese sulfate monohydrate in a ratio of 97:2:1 to form a metal solution with a total concentration of 2mol/L. Mix the metal solution, ammonia with a concentration of 8mol/L, and The 10mol/L sodium hydroxide solution is passed into the reaction kettle through a metering pump at a flow rate of 25L/h of metal solution, 9L/h of sodium hydroxide solution, and 1.5L/h of ammonia water. After the liquid is introduced, the pH of the original reaction bottom liquid is maintained. For 12, the nucleation reaction takes 3-7 hours, the particles grow up, and the prepared polycrystalline particles overflow into the aging tank;

Sc: Slowly lower the pH and stir as the secondary particles grow. When D50≤3.5, the pH is 11.6, stirring: 500rpm. When 3.5<D50≤7.5, pH: 11.5, stirring: 350rpm. When 7.5<D50≤ 10.5, pH: 11.1, stirring: 250rpm; target particle size: 10.1-10.5μm, to reach the target particle size D50 and grow to 10.3μm, increase the pH to 12.5, and maintain it for 30 minutes, then adjust to the original pH, repeat the operation, centrifuge, After drying, batch mixing, sieving and demagnetization, the ultra-high nickel ternary precursor Ni _0.9685 Co _0.02 Mn _0.01 M _0.0015 (OH) ₂ was obtained.

Comparative example 1

Comparative Example 1 provides a battery, and the difference between its preparation method and that of Example 1 is that step S11 specifically includes:

Sa: Input clean water into the reaction kettle, and ensure that the clean water can flood the pH probe. Heat the reaction kettle to 60°C, start stirring and maintain 550rpm, add ammonia water with a concentration of 3g/L, adjust the pH to 12.5, and obtain the reaction bottom liquid;

Sb: Mix nickel sulfate hexahydrate, cobalt sulfate heptahydrate, and manganese sulfate monohydrate in a ratio of 97:2:1 to form a metal solution with a total concentration of 2mol/L. Mix the metal solution, ammonia with a concentration of 9mol/L, and The 12mol/L sodium hydroxide solution was passed into the reaction kettle through a metering pump at a flow rate of 25L/h for metal solution, 9L/h for sodium hydroxide solution, and 1.5L/h for ammonia water. After the liquid was introduced, the original reaction bottom liquid conditions were maintained. Change, nucleation reaction takes 3-7 hours, grows to 10.3 microns, and finds the nucleation point. The particle size is greater than 10.5, and the pH is 0.2 higher than the nucleation point. If the particle size is less than 10.5, the pH remains 0.2 below the nucleation point. The prepared polycrystalline particles overflow. The flow enters the aging tank;

Sc: As the secondary particles grow, slowly lower the pH and stir to reach the target particle size D50 and grow to 10.3 μm. Repeat the operation, centrifuge, dry, mix the batch, sieve, and demagnetize to obtain the ultra-high nickel ternary precursor. .

Comparative example 2

Comparative Example 2 provides a battery, and the difference between its preparation method and that of Example 1 is that step S11 specifically includes:

Sa: Input clean water into the reaction kettle, and ensure that the clean water can submerge the pH probe. Heat the reaction kettle to 60°C, start stirring and maintain 500rpm, add ammonia water with a concentration of 2.3g/L, adjust the pH to 12, and obtain the reaction bottom liquid;

Sb: Mix nickel sulfate hexahydrate, cobalt sulfate heptahydrate, and manganese sulfate monohydrate in a ratio of 97:2:1 to form a metal solution with a total concentration of 2mol/L. Add 150g zirconium sulfate to every 100kg sodium hydroxide solution to prepare an alkali solution. , pass the metal solution, ammonia water and alkali liquid into the reaction kettle through a metering pump at a flow rate of 25L/h for metal solution, 9L/h for alkali liquid, and 1.5L/h for ammonia water. After the liquid is introduced, the original reaction bottom liquid conditions remain unchanged. , the nucleation reaction takes 3-7 hours, the particles grow up, and the prepared polycrystalline particles overflow into the aging tank;

Sc: As the secondary particles grow, maintain the same concentration of ammonia and pH to reach the target particle size D50 and grow to 10.3 μm. Centrifuge, dry, mix batches, sieve, and demagnetize to obtain an ultra-high nickel ternary precursor.

Experimental example 1

The ultra-high nickel ternary precursor prepared in step S11 of Examples 1-5 and Comparative Examples 1-2 was subjected to performance testing. The testing included nitrogen adsorption (BET) test, tap density test, sulfur content and particle size test. . Among them, the tap density test uses a tap density meter to test, and the particle size test uses a particle size meter to test D50 data. The test results are shown in Table 1.

Table 1. Performance test results of ultra-high nickel ternary precursor

According to the comparison between Examples 1-5 and Comparative Examples 1-2 in Table 1, it can be seen that the porous spherical ternary precursor prepared by the preparation method provided by the embodiments of the present invention has the advantages of large specific surface area and high compaction. At the same time, the preparation method provided by the embodiment of the present invention can also reduce the sulfur content in the precursor by rapidly increasing the pH after the precursor reaches the target particle size, thereby fully reducing the manufacturing cost.

In addition, according to the comparison of data in Examples 1-4, it can be seen that after the secondary particles grow to the target particle size, the higher the pH in the reaction kettle, the larger the particle size of the secondary particles finally obtained; however, due to the During the particle forming process, the primary particles can be ensured to be fine, short and uniform, and the secondary particles are gradually reduced in pH during the forming process, so that the secondary particles can have a porous spherical structure, thus making the particles with larger particle sizes larger. The precursor can also obtain better specific surface area and tap density; and compared with Comparative Example 1-2, the specific surface area and tap density can be simultaneously improved; at the same time, according to Examples 1-4 and Embodiment 5 It can be seen from the comparison that under the same preparation environment, doping M-containing compounds in the precursor will significantly increase the particle size of the precursor particles and reduce the specific surface area and tap density to a certain extent. However, due to the thin and short structure of the primary particles, the secondary particles The secondary particles are porous and spherical, so that the specific surface area and tap density of the precursor will not decrease too much. Compared with Comparative Examples 1-2, the specific surface area and tap density can still be simultaneously increased.

Experimental example 2

The batteries prepared in step S3 of Examples 1-5 and Comparative Examples 1-2 were subjected to performance tests. The test items included charging capacity (0.1C) test and cycle retention rate test. The cycle test was specifically tested at 25°C. Capacity retention rate under the conditions of charging from 2C to 4.5V and then charging from 1.5C to 4.5V with a cut-off current of 0.05C. The test results are shown in Table 2.

Table 2. Battery performance test results

According to the comparison between Examples 1-5 and Comparative Examples 1-2 in Table 2, it can be seen that the battery prepared by using the porous spherical ternary precursor provided by the embodiments of the present invention has better cycle performance and better charging capacity. As a result, the battery provided by the embodiment of the present invention has more excellent electrochemical performance. At the same time, according to the comparison between Examples 1-4 and Example 5 in Table 2, it can be seen that the embodiments of the present invention can improve the charging capacity and cycle performance to a certain extent by doping metal elements in the porous spherical ternary precursor.

In summary, embodiments of the present invention provide a porous spherical ternary precursor and a preparation method thereof, which can achieve the organic unity of large specific surface area and high vibration while ensuring the cycle performance of the battery, so as to fully improve the battery life. The electrochemical performance of the battery. Embodiments of the present invention also provide a ternary positive electrode material, a positive electrode sheet and a battery, all of which are prepared by the above-mentioned porous spherical ternary precursor. Therefore, it also has the advantage of improving the electrochemical performance of the battery.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

A method for preparing a porous spherical ternary precursor, which is characterized by including:

Pour the metal solution, ammonia water and alkali solution obtained by mixing the nickel salt, cobalt salt and manganese salt into a reaction kettle with a reaction bottom liquid with a pH of 11.5-12.5, start stirring and maintain the pH in the reaction kettle at 11.5-12.5 Perform granulation to form primary granules;

Continue granulation to agglomerate the primary particles to form secondary particles. During the process of the secondary particles growing to the target particle size, gradually reduce the pH in the reaction kettle to 11-11.5, and gradually reduce the stirring speed simultaneously. In order to make the secondary particles gradually grow into porous spherical shapes, and after the secondary particles grow to the target particle size, the pH in the reaction kettle is rapidly raised to 11.5-12.5 and maintained for a preset time. Obtain intermediate precursor;

The intermediate precursor is post-processed to obtain a porous spherical ternary precursor.
The preparation method of porous spherical ternary precursor according to claim 1, characterized in that:

The target particle size of the secondary particles is 10.1<D50≤10.5μm;

Preferably, during the formation of the secondary particles, the steps of gradually reducing the pH in the reaction kettle to 11-11.5 and simultaneously gradually reducing the stirring speed include:

When the D50 of the secondary particles ≤ 3.5 μm, the pH is adjusted to 11.5-12.5, and the stirring speed is adjusted to 450-550 rpm; when the secondary particles are 3.5 < D50 ≤ 7.5 μm, the pH is adjusted to 11.5 -11.8, the stirring speed is adjusted to 300-450rpm; when the secondary particles are 7.5<D50≤10.1μm, the pH is adjusted to 11-11.5, and the stirring speed is adjusted to 250-300rpm.
The preparation method of porous spherical ternary precursor according to claim 1, characterized in that:

Before the metal solution is mixed with the alkali solution, it also includes adding an M-containing compound into the metal solution;

Preferably, the M-containing compound is one of molybdenum trioxide, tungsten trioxide, and zirconium sulfate;

Preferably, 610-700g of the M-containing compound needs to be added to every 800-900L of the metal solution.
The preparation method of porous spherical ternary precursor according to claim 3, characterized in that:

The general chemical formula of the porous spherical ternary precursor is N 0.02; x+y+z+w=1;

Preferably, the specific surface area of the porous spherical ternary precursor is 13-15m 2 /g;

Preferably, the tap density of the porous spherical ternary precursor is 2.05-2.30g/cm 3 ;

Preferably, the sulfur content of the porous spherical ternary precursor is 1500-1800 ppm;

Preferably, the nickel salt is any one of nickel sulfate hexahydrate and nickel chloride;

Preferably, the cobalt salt is any one of cobalt sulfate heptahydrate and cobalt chloride;

Preferably, the manganese salt is manganese sulfate monohydrate.
The preparation method of porous spherical ternary precursor according to claim 1, characterized in that:

The flow rate of the metal solution flowing into the reaction kettle is 20-40L/h; the flow rate of the alkali liquid flowing into the reaction kettle is 8-18L/h;

and / or,

The concentration of the metal solution is 1.6-2.2mol/L;

and / or,

The ammonia concentration is 1.8-3.2g/L;

and / or,

The alkali solution is sodium hydroxide solution; preferably, the concentration of the sodium hydroxide solution is 6-12 mol/L;

and / or,

The stirring speed to form the primary particles is maintained at 450-550 rpm;

and / or,

The nucleation reaction time to form the primary particles is 3-7h;

and / or,

The preset time is 10-40min.
The preparation method of porous spherical ternary precursor according to claim 1, characterized in that:

The reaction bottom liquid is obtained by adding ammonia water to the heated clear water while stirring;

Preferably, the heating temperature range of the clean water is 55-75°C;

Preferably, the stirring speed is maintained at 450-550 rpm.
A porous spherical ternary precursor, characterized in that the porous spherical ternary precursor is prepared by the preparation method of a porous spherical ternary precursor according to any one of claims 1 to 6.
A ternary cathode material, characterized by comprising a porous spherical ternary precursor prepared by the preparation method of a porous spherical ternary precursor according to any one of claims 1 to 6; or, comprising the porous spherical ternary precursor according to claim 7 The porous spherical ternary precursor described above.
A positive electrode sheet, characterized in that it includes the positive electrode material according to claim 8.
A battery, characterized by comprising the positive electrode sheet according to claim 9.