CN115745023A - High-voltage nickel-cobalt-manganese hydroxide, preparation method thereof, positive electrode material and lithium ion battery - Google Patents

Abstract

The invention provides a high-voltage nickel-cobalt-manganese hydroxide, a preparation method thereof, a positive electrode material and a lithium ion battery. The preparation method comprises: a metal solution A containing Ni, Co and Mn, a metal solution B containing Ta and an alkali Co-precipitation reaction is carried out to obtain Ta-doped nickel-cobalt-manganese hydroxide matrix dispersion; add alcohols to the Ta-doped nickel-cobalt-manganese hydroxide matrix dispersion, and then add Silicate esters are reacted to obtain the nickel-cobalt-manganese hydroxide. The invention utilizes the coating reaction in the alkaline environment in the doping stage, constructs a coating layer on the surface of the Ta-doped nickel-cobalt-manganese hydroxide substrate, and can enhance the structural stability of the material.

Description

High-voltage nickel-cobalt-manganese hydroxide, its preparation method, positive electrode material and lithium-ion battery

technical field

The invention belongs to the technical field of cathode materials, and relates to a high-voltage nickel-cobalt-manganese hydroxide, a preparation method thereof, an anode material and a lithium ion battery.

Background technique

Lithium-ion batteries are widely used in notebook computers, mobile phones and all-electric vehicles, and have received more and more attention. At present, the ternary cathode material LiNi _x Co _y Mn _1-xy O ₂ (NCM), where x ≥ 0.6, has become the focus of attention because of its high practical capacity at relatively high voltage, in terms of long driving mileage has obvious advantages. However, with the increase of Ni content and voltage, cathode materials face the plight of thermal instability and severe degradation of cycle stability. Layered cathode materials usually lead to layered R-3m phase transformation to spinel Fd-3m phase and finally rock-salt Fm-3m phase due to Li/Ni mixing, which is detrimental to cycle stability. Raising the cut-off voltage can effectively increase the energy density, however, it is considered as a radical way, and when the charge cut-off voltage is increased excessively, the capacity of NCM is also significantly weakened. Inherent problems of NCM cathodes include surface structural phase transition, electrochemical polarization, lattice mismatch, and grain cracks, etc.

At present, various modification methods such as doping elements, surface modification, and concentration gradient design have been proposed to solve the problems of capacity fading and cycle stability of high-nickel ternary cathode materials. Cation doping is one of the effective methods, and the doping elements are usually Mg, Al, Ti, Ce, Zr, and Nb. First, cation doping can suppress Li/Ni mixing by increasing the Ni ²⁺ migration energy barrier; second, due to the stronger metal-oxygen bond energy compared to Ni-O bonds, the enhanced Structural stability of the Ni-rich cathode with suppressed oxygen release. CN112670506B discloses a fast ion conductor-coated nickel-cobalt-manganese-tantalum composite quaternary positive electrode material and its preparation method, comprising the following steps: taking lithium salt and tantalum salt for powder treatment, and then mixing nickel-cobalt-manganese ternary positive electrode material precursor body to obtain a homogeneous mixture; the homogeneous mixture is calcined in stages, first at 450-550°C, then at 680-780°C, and after cooling in the furnace, the nickel-cobalt-manganese-tantalum composite quaternary positive electrode material is obtained. CN114122380A discloses a method for preparing a zirconium-doped cerium fluoride-coated nickel-cobalt-manganese ternary positive electrode material. The nickel-cobalt-manganese hydroxide precursor, lithium source, and zirconium source are mixed by ball milling and sintered to obtain zirconium-doped Nickel-cobalt-manganese ternary cathode material. The above two patents improve the doping and mixing effect of elements through pulverization treatment. However, it is difficult to achieve the mixing of material elements at the molecular level by means of physical mixing. Uneven mixing of elements will affect the stability of performance, and the mixing method increases The operating procedure is increased, and the cost is increased.

In addition, surface modification is also an effective strategy to maintain the stability of the surface structure. CN104362330A discloses a nickel-cobalt lithium manganese oxide material coated with a boron-lithium composite oxide on the surface, which is coated with a layer of nickel-cobalt lithium manganate cathode material on the surface Boron lithium composite oxide. The preparation method of the material is to add the prepared nickel-cobalt lithium manganate into the mixed alcohol solution of the lithium source and the boron source, ultrasonically disperse it in the solution, and then add a dispersant to fully soak the material in the solution , heat treatment after evaporation of the solvent to obtain the material. The surface coating layer can maintain the layered structure of the NCM surface and ensure the structural stability of the NCM material.

Therefore, there is an urgent need for a method for preparing NCM materials suitable for industrial production. NCM materials are doped with cations at the molecular level and a cladding layer is constructed on the surface to improve the structural stability of NCM materials.

Contents of the invention

Aiming at the deficiencies in the prior art, the object of the present invention is to provide high-voltage nickel-cobalt-manganese hydroxide, its preparation method, positive electrode material and lithium ion battery. The preparation method of the present invention performs Ta doping in the preparation stage of the nickel-cobalt-manganese hydroxide matrix, which realizes the mixing at the molecular level; utilizes the alkaline environment in the doping stage to carry out the coating reaction, and the Ta-doped nickel-cobalt-manganese hydroxide A coating is constructed on the surface of the substrate. The structure stability of the material can be enhanced by adopting the preparation method of the invention.

The "high voltage" in the "high-voltage nickel-cobalt-manganese hydroxide" in the present invention means that the positive electrode material prepared from nickel-cobalt-manganese hydroxide has a high charge cut-off voltage, and the high charge cut-off voltage is greater than or equal to 4.5V.

For reaching this purpose, the present invention adopts following technical scheme:

In a first aspect, the present invention provides a method for preparing nickel-cobalt-manganese hydroxide, the preparation method comprising:

(1) The metal solution A containing Ni, Co and Mn, the metal solution B containing Ta and the alkaline solution are added to the bottom solution in parallel, and a coprecipitation reaction is carried out to obtain a Ta-doped nickel-cobalt-manganese hydroxide matrix dispersion ;

(2) Add alcohols to the Ta-doped nickel-cobalt-manganese hydroxide matrix dispersion liquid in step (1), and then add silicate to react to obtain the nickel-cobalt-manganese hydroxide.

The invention provides a method for preparing nickel-cobalt-manganese hydroxide. On the one hand, Ta is doped in the nickel-cobalt-manganese hydroxide matrix, and the Ta doping is mainly lithium-site doping, which can suppress the disorder of lithium/nickel degree, play a pillar effect, and stabilize the structure of the material. Moreover, Ta doping during the preparation of the matrix can achieve molecular level mixing and improve the reliability of the material. On the other hand, the cladding reaction is carried out in the alkaline environment of the doping stage, and a cladding layer is constructed on the surface of the Ta-doped nickel-cobalt-manganese hydroxide substrate, which enhances the structural stability of the material. The preparation method provided by the invention can effectively improve the structural stability of the material, and can effectively adjust and monitor the process of doping and coating. In addition, the doping and coating processes of the present invention can be carried out in the same reaction vessel without cumbersome procedures, saving costs and facilitating industrial production.

As a preferred technical solution of the present invention, the alkaline solution includes sodium hydroxide solution and ammonia solution.

The present invention does not specifically limit the phase state of sodium hydroxide, for example, it may be liquid caustic soda. The sodium hydroxide solution can be prepared by using liquid caustic soda.

Preferably, the flow ratio of the metal solution A, the metal solution B, the sodium hydroxide solution and the ammonia solution is 10:(0.16～3):(3.2～4.5):(0.3～0.7), Wherein, the selection range of 0.16～3 of the metal solution B can be, for example, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1; the selection range of the sodium hydroxide solution 3.2～4.5 can be, for example, 3.2, 3.3, 3.4, 3.5 , 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4 or 4.5; the selection range of ammonia solution 0.3～0.7 can be 0.3, 0.4, 0.5, 0.6 or 0.7, but not limited to the listed values , other unlisted values within the value range are also applicable.

Preferably, the metal solution A includes Ni-containing compounds, Co-containing compounds and Mn-containing compounds.

Preferably, the Ni-containing compound includes at least one of NiSO ₄ , Ni(NO ₃ ) ₂ and NiCl ₂ .

Preferably, the Co-containing compound includes at least one of CoSO ₄ , Co(NO ₃ ) ₂ and CoCl ₂ .

Preferably, the Mn-containing compound includes at least one of MnSO ₄ , Mn(NO ₃ ) ₂ and MnCl ₂ .

Preferably, in the metal solution A, the total concentration of Ni, Co and Mn is 1.6-2.4 mol/L, such as 1.6 mol/L, 1.7 mol/L, 1.8 mol/L, 1.9 mol/L, 2.0 mol/L, 2.1mol/L, 2.2mol/L, 2.3mol/L or 2.4mol/L, but not limited to the listed values, other unlisted values within the range of values are also applicable.

Preferably, in the metal solution A, the molar ratio of Ni, Co and Mn is Ni:Co:Mn=x:y:z, wherein, x+y+z=1, 0.6<x<1, for example, x It can be 0.65, 0.7, 0.75, 0.8, 0.85, 0.9 or 0.95, but it is not limited to the listed values, and other unlisted values within the range of values are also applicable.

Preferably, the metal solution B includes NaTaO ₃ and/or NaTaO ₅ .

Preferably, in the metal solution B, the concentration of Ta is 0.04-0.1 mol/L, such as 0.04 mol/L, 0.05 mol/L, 0.06 mol/L, 0.07 mol/L, 0.08 mol/L, 0.09 mol/L or 0.1mol/L, but not limited to the listed values, other unlisted values within the range of values are also applicable.

Preferably, the ratio of the total molar weight of Ni, Co and Mn in the metal solution A to the molar weight of Ta in the metal solution B is (200-999):1, for example, it can be 200:1, 300:1 , 400:1, 500:1, 600:1, 700:1, 800:1, 900:1 or 999:1, but not limited to the listed values, other unlisted values within the range are also applicable.

In the present invention, the ratio of the total molar weight of Ni, Co and Mn in the metal solution A to the molar weight of Ta in the metal solution B has a preferred range, if the ratio is lower than 200:1, it will make the nickel cobalt manganese hydroxide matrix If the Ta doping content is too high, because Ta is inactive, too much Ta will lead to a lower capacity of the positive electrode material; if the ratio is higher than 999:1, it will make Ta doping in the nickel-cobalt-manganese hydroxide matrix If the content is too low, too little Ta cannot effectively improve the structural stability of the material, resulting in poor structural stability of the material, and the prepared positive electrode material exhibits a low capacity retention rate.

Preferably, the concentration of the sodium hydroxide solution is 9-12 mol/L, such as 9 mol/L, 9.5 mol/L, 10 mol/L, 10.5 mol/L, 11 mol/L, 11.5 mol/L or 12 mol/L L, but not limited to the listed values, other unlisted values within the range of values are also applicable.

Preferably, the concentration of the ammonia solution is 7-10 mol/L, such as 7 mol/L, 7.5 mol/L, 8 mol/L, 8.5 mol/L, 9 mol/L, 9.5 mol/L or 10 mol/L, But not limited to the listed values, other unlisted values within the range of values are also applicable.

Preferably, the bottom liquid includes water, ammonia and sodium hydroxide.

The present invention does not specifically limit the phase state of the sodium hydroxide used to prepare the bottom liquid, and it can be liquid caustic soda as an example.

As a preferred technical solution of the present invention, the alcohols include at least one of methanol, ethanol, propanol and butanol.

Preferably, the silicates include tetraethylorthosilicate.

Preferably, the ratio of the total molar weight of Ni, Co and Mn in the Ta-doped nickel-cobalt-manganese hydroxide matrix dispersion to the molar weight of Si in the silicate is 100:(0.5～1), For example, it can be 100:0.5, 100:0.55, 100:0.6, 100:0.65, 100:0.7, 100:0.75, 100:0.8, 100:0.85, 100:0.9, 100:0.95 or 100:1, but not only Limited to the numerical values listed, other unlisted numerical values within the numerical range are also applicable.

In the present invention, the ratio of the total molar weight of Ni, Co and Mn in the dispersion liquid to the molar weight of Si in tetraethyl orthosilicate has a preferred range, if the ratio is lower than 100:1, it will cause the coating layer to be too thick and inhibit The performance of the positive electrode material is due to the thick coating layer, which reduces the proportion of the effective active material of the material, hinders ion migration, and leads to a poor electrochemical performance; if the ratio is higher than 100:0.5, resulting in coating The coating is too thin, because the thin coating layer cannot effectively suppress the boundary reaction, thereby reducing the electrochemical stability of the material.

As a preferred technical solution of the present invention, during the co-precipitation reaction described in step (1), the pH is controlled within the range of 10 to 13, such as 10, 10.5, 11, 11.5, 12, 12.5 or 13, but It is not limited to the numerical values listed, and other unlisted numerical values within the numerical range are also applicable.

Preferably, during the co-precipitation reaction in step (1), the temperature is controlled within the range of 40-70°C, for example, it can be 40°C, 45°C, 50°C, 55°C, 60°C, 65°C or 70°C, But not limited to the listed values, other unlisted values within the range of values are also applicable.

Preferably, the process of the co-precipitation reaction described in step (1) is carried out under stirring, and the rotating speed of the stirring is 250～420rpm, such as 250rpm, 280rpm, 300rpm, 320rpm, 350rpm, 380rpm, 400rpm or 420rpm, but not Not limited to the listed values, other unlisted values within the range of values are also applicable.

As a preferred technical solution of the present invention, during the reaction described in step (2), the temperature is controlled within the range of 40°C to 70°C, such as 40°C, 45°C, 50°C, 55°C, 60°C, 65°C °C or 70 °C, but not limited to the listed values, other unlisted values within the range of values are also applicable.

Preferably, the reaction process in step (2) is carried out under stirring, and the stirring speed is 250-420rpm, such as 250rpm, 280rpm, 300rpm, 320rpm, 350rpm, 380rpm, 400rpm or 420rpm, but not limited to For the listed values, other unlisted values within the range of values also apply.

As a preferred technical solution of the present invention, the preparation method specifically includes the following steps:

(I) the metal solution A that the total concentration of preparation Ni, Co and Mn is 1.6～2.4mol/L, the mol ratio of Ni, Co and Mn is Ni:Co:Mn=x:y:z, wherein, x+y +z=1, 0.6<x<1;

Prepare metal solution B with a Ta concentration of 0.04-0.1 mol/L;

Prepare a sodium hydroxide solution with a concentration of 9-12mol/L;

Prepare an ammonia solution with a concentration of 7-10mol/L;

(II) Prepare the bottom liquid in the reaction vessel, then add metal solution A, metal solution B and sodium hydroxide solution in parallel at a flow ratio of 10:(0.16～3):(3.2～4.5):(0.3～0.7) and ammonia solution, carry out co-precipitation reaction, obtain Ta-doped nickel-cobalt-manganese hydroxide dispersion liquid;

(III) Add alcohols to the Ta-doped nickel-cobalt-manganese hydroxide matrix dispersion liquid, and then add silicate, and react to obtain the nickel-cobalt-manganese hydroxide.

In a second aspect, the present invention provides a nickel-cobalt-manganese hydroxide, which is prepared by the preparation method described in the first aspect.

Preferably, the nickel-cobalt-manganese hydroxide comprises a Ta-doped nickel-cobalt-manganese hydroxide substrate and a silicon-oxygen cladding layer covering the surface of the Ta-doped nickel-cobalt-manganese hydroxide substrate.

As a preferred technical solution of the present invention, the doping amount of Ta in the Ta-doped nickel-cobalt-manganese hydroxide matrix is 2000-10000ppm, preferably 2000-5000ppm, such as 2000ppm, 2500ppm, 3000ppm, 3500ppm, 4000ppm, 4500ppm, 5000ppm, 5500ppm, 6000ppm, 6500ppm, 7000ppm, 7500ppm, 8000ppm, 8500ppm, 9000ppm, 9500ppm or 10000ppm, but not limited to the listed values, other unlisted values within the range are also applicable.

Preferably, the thickness of the silicon-oxygen coating layer is 2-14nm, for example, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, 11nm, 12nm, 13nm or 14nm, but not limited to For the listed values, other unlisted values within the range of values also apply.

In a third aspect, the present invention provides a positive electrode material, which is obtained by mixing and sintering the nickel-cobalt-manganese hydroxide described in the second aspect and a lithium source.

Preferably, the positive electrode material includes a nickel-cobalt-lithium-manganese-oxide substrate and a lithiated silicon-oxygen coating layer coated on the surface of the nickel-cobalt-lithium-manganese-oxide substrate.

In the present invention, lithiated silicon oxide refers to a compound containing Li, Si, and O. The lithiated silicon-oxygen coating layer can separate the electrolyte from the nickel-cobalt-lithium-manganese-oxide matrix, maintain the layered structure on the surface of the nickel-cobalt-lithium-manganese-oxide, and stabilize the structure of the nickel-cobalt-lithium-manganese-oxide. In addition, the lithiated silicon-oxygen coating layer has a good ability to conduct lithium ions without affecting the transmission of lithium ions. Therefore, the prepared cathode materials can simultaneously have high capacity and high cycle stability.

Preferably, the lithium source includes lithium hydroxide and/or lithium carbonate.

Preferably, the molar ratio of the lithium source to the nickel-cobalt-manganese hydroxide transition metal is (1-1.08):1, such as 1:1, 1.01:1, 1.02:1, 1.03:1, 1.04:1 , 1.05:1, 1.06:1, 1.07:1 or 1.08:1, but not limited to the listed values, other unlisted values within the range of values are also applicable.

Preferably, the sintering temperature is 700-900°C, for example, it can be 700°C, 750°C, 800°C, 850°C or 900°C, but it is not limited to the listed values, and other unlisted values within the numerical range are the same Be applicable.

Preferably, the sintering time is 5-15h, for example, it can be 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h or 15h, but it is not limited to the listed values, within the range of Other values not listed also apply.

In a fourth aspect, the present invention provides a lithium ion battery, the positive electrode of the lithium ion battery includes the positive electrode material described in the third aspect.

The numerical ranges described in the present invention not only include the above-listed point values, but also include any point values between the above-mentioned numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention will not exhaustively list the ranges. The specific pip value to include.

Compared with prior art, the beneficial effect of the present invention is:

The invention provides a method for preparing nickel-cobalt-manganese hydroxide. On the one hand, Ta is doped in the nickel-cobalt-manganese hydroxide matrix, and Ta doping belongs to lithium-site doping, which can suppress the disorder of lithium/nickel , play a pillar effect and stabilize the structure of the material. Moreover, Ta doping during the preparation of the matrix can achieve molecular level mixing and improve the reliability of the material. On the other hand, the cladding reaction is carried out in the alkaline environment of the doping stage, and a cladding layer is constructed on the surface of the Ta-doped nickel-cobalt-manganese hydroxide substrate, which enhances the structural stability of the material. The preparation method provided by the invention can effectively improve the structural stability of the material, and can effectively adjust and monitor the process of doping and coating. In addition, the doping and coating processes of the present invention can be carried out in the same reaction vessel without cumbersome procedures, saving costs and facilitating industrial production.

Detailed ways

The technical solutions of the present invention will be further described below through specific embodiments.

Example 1

This embodiment provides a method for preparing nickel-cobalt-manganese hydroxide, and the preparation method specifically includes the following steps:

(1) Adopt NiSO ₄ , CoSO ₄ and Mn(NO ₃ ) ₂ to prepare metal solution A, wherein the total concentration of Ni, Co and Mn is 2.4mol/L, and the molar ratio of Ni, Co and Mn is 0.65:0.17: 0.18; the concentration of preparation Ta is the metal solution B of 0.04mol/L; the preparation concentration is the sodium hydroxide solution of 9mol/L; the preparation concentration is the ammonia solution of 7mol/L;

(2) Inject appropriate amount of water, ammonia and liquid caustic soda into the reaction vessel, carry out sufficient stirring and mixing to prepare the bottom liquid, the pH of the bottom liquid is 10～11, and then metal solution A, metal solution B, hydroxide The sodium solution and the ammonia solution are respectively fed into the reaction vessel at a flow rate of 10L/h, 3L/h, 3.2L/h and 0.3L/h in parallel. The molar ratio of Ta in solution B is 200:1, and the co-precipitation reaction is carried out under the conditions of pH 10.3-10.5 and temperature 40°C. The co-precipitation reaction is carried out under stirring, and the stirring speed is 250rpm. After the reaction, Ta Doped nickel cobalt manganese hydroxide dispersion;

(3) Under the condition that the temperature is 40°C and the stirring speed is 250rpm, ethanol is added to the Ta-doped nickel-cobalt-manganese hydroxide matrix dispersion liquid, and then tetraethyl orthosilicate is added to control the Ni in the dispersion liquid. The ratio of the total molar weight of Co, Mn and Ta to the molar weight of Si in tetraethyl orthosilicate is 100:0.5, and the nickel-cobalt-manganese hydroxide is obtained through drying after the reaction.

The nickel-cobalt-manganese hydroxide prepared in this embodiment includes a Ta-doped nickel-cobalt-manganese hydroxide matrix and a silicon-oxygen coating layer coated on the surface of the matrix, and the Ta doping in the Ta-doped nickel-cobalt-manganese hydroxide matrix The impurity amount was 10000 ppm, and the thickness of the silicon-oxygen coating layer was 2 nm.

This embodiment also provides a positive electrode material, the preparation method of the positive electrode material is as follows:

Mix nickel-cobalt-manganese hydroxide and lithium hydroxide and sinter at 850° C. for 8 hours to obtain the positive electrode material.

Example 2

This embodiment provides a method for preparing nickel-cobalt-manganese hydroxide, and the preparation method specifically includes the following steps:

(1) Adopt NiSO ₄ , CoSO ₄ and Mn(NO ₃ ) ₂ to prepare metal solution A, wherein the total concentration of Ni, Co and Mn is 2.4mol/L, and the molar ratio of Ni, Co and Mn is 0.8:0.1: 0.1; the concentration of preparation Ta is the metal solution B of 0.06mol/L; the preparation concentration is the sodium hydroxide solution of 11mol/L; the preparation concentration is the ammonia solution of 10mol/L;

(2) Inject appropriate amount of water, ammonia and liquid caustic soda into the reaction vessel, carry out sufficient stirring and mixing to prepare the bottom liquid, the pH of the bottom liquid is 11～12, and then metal solution A, metal solution B, hydroxide Sodium solution and ammonia solution are respectively added in the reaction vessel with the flow parallel flow of 10L/h, 0.45L/h, 4.36L/h and 0.4L/h, and the total molar weight of Ni, Co and Mn in the metal solution A added is equal to The molar ratio of Ta in the metal solution B is 889:1, and the co-precipitation reaction is carried out under the conditions of pH 11.2-11.5 and temperature 47°C. The co-precipitation reaction is carried out under stirring, and the stirring speed is 292rpm. After the reaction, Ta-doped nickel-cobalt-manganese hydroxide dispersion;

(3) Under the condition that the temperature is 47° C. and the stirring speed is 292 rpm, add ethanol to the Ta-doped nickel-cobalt-manganese hydroxide matrix dispersion liquid, and then add tetraethyl orthosilicate to control the Ni in the dispersion liquid. The ratio of the total molar weight of Co, Mn and Ta to the molar weight of Si in tetraethyl orthosilicate is 100:0.5, and the nickel-cobalt-manganese hydroxide is obtained through drying after the reaction.

The nickel-cobalt-manganese hydroxide prepared in this embodiment includes a Ta-doped nickel-cobalt-manganese hydroxide matrix and a silicon-oxygen coating layer coated on the surface of the matrix, and the Ta doping in the Ta-doped nickel-cobalt-manganese hydroxide matrix The impurity amount is 2100, and the thickness of the silicon-oxygen coating layer is 2 nm.

This embodiment also provides a positive electrode material, the preparation method of the positive electrode material is as follows:

Mix nickel-cobalt-manganese hydroxide and lithium hydroxide and sinter at 750° C. for 8 hours to obtain the positive electrode material.

Example 3

This embodiment provides a method for preparing nickel-cobalt-manganese hydroxide, and the preparation method specifically includes the following steps:

(1) Adopt NiSO ₄ , CoCl ₂ and Mn(NO ₃ ) ₂ to prepare metal solution A, wherein the total concentration of Ni, Co and Mn is 2.3mol/L, and the molar ratio of Ni, Co and Mn is 0.8:0.1: 0.1; the concentration of preparation Ta is the metal solution B of 0.06mol/L; the preparation concentration is the sodium hydroxide solution of 10.5mol/L; the preparation concentration is the ammonia solution of 8.5mol/L;

(2) Inject appropriate amount of water, ammonia and liquid caustic soda into the reaction vessel, carry out sufficient stirring and mixing to prepare the bottom liquid, the pH of the bottom liquid is 11～12, and then metal solution A, metal solution B, hydroxide Sodium solution and ammonia solution are fed into the reaction vessel in parallel with the flow rate of 10L/h, 0.8L/h, 3.85L/h and 0.5L/h respectively, and the total molar weight of Ni, Co and Mn in the metal solution A added is equal to The molar ratio of Ta in the metal solution B is 479:1, the co-precipitation reaction is carried out under the conditions of pH 11.2-11.5 and temperature 55°C, the co-precipitation reaction is carried out under stirring, and the stirring speed is 335rpm. After the reaction, Ta-doped nickel-cobalt-manganese hydroxide dispersion;

(3) Under the condition that the temperature is 55° C. and the stirring speed is 335 rpm, ethanol is added to the Ta-doped nickel-cobalt-manganese hydroxide matrix dispersion liquid, and then tetraethyl orthosilicate is added to control the Ni in the dispersion liquid. The ratio of the total molar weight of Co, Mn and Ta to the molar weight of Si in tetraethyl orthosilicate is 100:0.75, and after the reaction, the nickel-cobalt-manganese hydroxide is obtained through drying treatment.

The nickel-cobalt-manganese hydroxide prepared in this embodiment includes a Ta-doped nickel-cobalt-manganese hydroxide matrix and a silicon-oxygen coating layer coated on the surface of the matrix, and the Ta doping in the Ta-doped nickel-cobalt-manganese hydroxide matrix The impurity amount was 4100 ppm, and the thickness of the silicon-oxygen coating layer was 8 nm.

This embodiment also provides a positive electrode material, the preparation method of the positive electrode material is as follows:

Mix nickel-cobalt-manganese hydroxide and lithium hydroxide and sinter at 750° C. for 8 hours to obtain the positive electrode material.

Example 4

This embodiment provides a method for preparing nickel-cobalt-manganese hydroxide, and the preparation method specifically includes the following steps:

(1) Adopt NiCl ₂ , CoSO ₄ and MnCl ₂ to prepare metal solution A, wherein the total concentration of Ni, Co and Mn is 1.85mol/L, and the molar ratio of Ni, Co and Mn is 0.9:0.5:0.5; prepare Ta The concentration is the metal solution B of 0.07mol/L; The preparation concentration is the sodium hydroxide solution of 11mol/L; The preparation concentration is the ammonia solution of 9mol/L;

(2) Inject appropriate amount of water, ammonia and liquid caustic soda into the reaction vessel, carry out sufficient stirring and mixing to prepare the bottom liquid, the pH of the bottom liquid is 12～13, then metal solution A, metal solution B, hydroxide Sodium solution and ammonia solution are fed into the reaction vessel in parallel with the flow rate of 10L/h, 0.8L/h, 4.2L/h and 0.4L/h respectively, and the total molar weight of Ni, Co and Mn in the metal solution A added is equal to The molar ratio of Ta in the metal solution B is 330:1, the co-precipitation reaction is carried out under the conditions of pH 12.3-12.5 and temperature 62°C, the co-precipitation reaction is carried out under stirring, and the stirring speed is 377rpm. After the reaction, Ta-doped nickel-cobalt-manganese hydroxide dispersion;

(3) Under the condition that the temperature is 62°C and the stirring speed is 377rpm, ethanol is added to the Ta-doped nickel-cobalt-manganese hydroxide matrix dispersion liquid, and then tetraethyl orthosilicate is added to control the Ni in the dispersion liquid. The ratio of the total molar weight of Co, Mn and Ta to the molar weight of Si in tetraethyl orthosilicate is 100:0.83, and the nickel-cobalt-manganese hydroxide is obtained through drying after the reaction.

The nickel-cobalt-manganese hydroxide prepared in this embodiment includes a Ta-doped nickel-cobalt-manganese hydroxide matrix and a silicon-oxygen coating layer coated on the surface of the matrix, and the Ta doping in the Ta-doped nickel-cobalt-manganese hydroxide matrix The impurity amount was 5900 ppm, and the thickness of the silicon-oxygen coating layer was 10 nm.

This embodiment also provides a positive electrode material, the preparation method of the positive electrode material is as follows:

Mix nickel-cobalt-manganese hydroxide, lithium hydroxide and lithium carbonate and sinter at 700° C. for 7 hours to obtain the positive electrode material.

Example 5

This embodiment provides a method for preparing nickel-cobalt-manganese hydroxide, and the preparation method specifically includes the following steps:

(1) Using Ni(NO ₃ ) ₂ , Co(NO ₃ ) ₂ and Mn(NO ₃ ) ₂ to prepare metal solution A, wherein the total concentration of Ni, Co and Mn is 1.6mol/L, Ni, Co and Mn The molar ratio of Ta is 0.95:0.02:0.03; The concentration of preparation Ta is the metal solution B of 0.1mol/L; The preparation concentration is the sodium hydroxide solution of 12mol/L; The preparation concentration is the ammonia solution of 10mol/L;

(2) Inject appropriate amount of water, ammonia and liquid caustic soda into the reaction vessel, carry out sufficient stirring and mixing to prepare the bottom liquid, the pH of the bottom liquid is 12～13, then metal solution A, metal solution B, hydroxide Sodium solution and ammonia solution are fed into the reaction vessel in parallel with the flow rate of 10L/h, 0.17L/h, 4.5L/h and 0.7L/h respectively, and the total molar weight of Ni, Co and Mn in the metal solution A added is equal to The molar ratio of Ta in the metal solution B is 941:1, the co-precipitation reaction is carried out under the conditions of pH 12.7-13.0 and temperature 70°C, the co-precipitation reaction is carried out under stirring, and the stirring speed is 420rpm. After the reaction, Ta-doped nickel-cobalt-manganese hydroxide dispersion;

(3) Under the condition that the temperature is 70°C and the stirring speed is 420rpm, add ethanol to the Ta-doped nickel-cobalt-manganese hydroxide matrix dispersion liquid, and then add tetraethyl orthosilicate to control the Ni in the dispersion liquid. The ratio of the total molar weight of Co, Mn and Ta to the molar weight of Si in tetraethyl orthosilicate is 100:1, and the nickel-cobalt-manganese hydroxide is obtained through drying after the reaction.

The nickel-cobalt-manganese hydroxide prepared in this embodiment includes a Ta-doped nickel-cobalt-manganese hydroxide matrix and a silicon-oxygen coating layer coated on the surface of the matrix, and the Ta doping in the Ta-doped nickel-cobalt-manganese hydroxide matrix The impurity amount was 2100 ppm, and the thickness of the silicon-oxygen coating layer was 14 nm.

This embodiment also provides a positive electrode material, the preparation method of the positive electrode material is as follows:

Mix nickel-cobalt-manganese hydroxide and lithium hydroxide and sinter at 700° C. for 6 hours to obtain the positive electrode material.

Example 6

This embodiment provides a method for preparing nickel-cobalt-manganese hydroxide, and the preparation method specifically includes the following steps:

(1) Using Ni(NO ₃ ) ₂ , Co(NO ₃ ) ₂ and Mn(NO ₃ ) ₂ to prepare metal solution A, wherein the total concentration of Ni, Co and Mn is 1.9mol/L, Ni, Co and Mn The molar ratio of Ta is 0.8:0.1:0.1; The concentration of preparation Ta is the metal solution B of 0.08mol/L; The preparation concentration is the sodium hydroxide solution of 11mol/L; The preparation concentration is the ammonia solution of 9mol/L;

(2) Inject appropriate amount of water, ammonia and liquid caustic soda into the reaction vessel, carry out sufficient stirring and mixing to prepare the bottom liquid, the pH of the bottom liquid is 11～12, and then metal solution A, metal solution B, hydroxide Sodium solution and ammonia solution are fed into the reaction vessel in parallel with the flow rate of 10L/h, 0.8L/h, 3.45L/h and 0.6L/h respectively, and the total molar weight of Ni, Co and Mn in the metal solution A added is equal to The molar ratio of Ta in the metal solution B is 297:1, the co-precipitation reaction is carried out under the conditions of pH 11.3-11.5 and temperature 70°C, the co-precipitation reaction is carried out under stirring, and the stirring speed is 420rpm. After the reaction, Ta-doped nickel-cobalt-manganese hydroxide dispersion;

(3) Under the condition that the temperature is 70°C and the stirring speed is 420rpm, add ethanol to the Ta-doped nickel-cobalt-manganese hydroxide matrix dispersion liquid, and then add tetraethyl orthosilicate to control the Ni in the dispersion liquid. The ratio of the total molar weight of Co, Mn and Ta to the molar weight of Si in tetraethyl orthosilicate is 100:0.5, and the nickel-cobalt-manganese hydroxide is obtained through drying after the reaction.

The nickel-cobalt-manganese hydroxide prepared in this embodiment includes a Ta-doped nickel-cobalt-manganese hydroxide matrix and a silicon-oxygen coating layer coated on the surface of the matrix, and the Ta doping in the Ta-doped nickel-cobalt-manganese hydroxide matrix The impurity amount was 6600 ppm, and the thickness of the silicon-oxygen coating layer was 2 nm.

This embodiment also provides a positive electrode material, the preparation method of the positive electrode material is as follows:

Mix nickel-cobalt-manganese hydroxide and lithium hydroxide and sinter at 750° C. for 8 hours to obtain the positive electrode material.

Example 7

This embodiment provides a kind of preparation method of nickel-cobalt-manganese hydroxide, and the difference with embodiment 3 is, in step (2), in the metal solution A, the total molar weight of Ni, Co and Mn is the same as that of Ta in the metal solution B. The ratio of the molar weight is adjusted to be 190:1, and other operation steps are identical with process parameter and embodiment 3.

This embodiment also provides a positive electrode material, and the preparation method of the positive electrode material is exactly the same as that in Example 3.

Example 8

This embodiment provides a kind of preparation method of nickel-cobalt-manganese hydroxide, and the difference with embodiment 3 is, in step (2), in the metal solution A, the total molar weight of Ni, Co and Mn is the same as that of Ta in the metal solution B. The ratio of the molar weight is adjusted to be 1009:1, and other operation steps are identical with process parameter and embodiment 3.

This embodiment also provides a positive electrode material, and the preparation method of the positive electrode material is exactly the same as that in Example 3.

Example 9

This embodiment provides a method for preparing nickel-cobalt-manganese hydroxide. The difference from Example 3 is that in step (3), the total molar weight of Ni, Co, Mn and Ta in the dispersion is equal to that of orthosilicate tetrachloride The molar ratio of Si in the ethyl ester was adjusted to 100:0.4, and the other operating steps were exactly the same as the process parameters and Example 3.

This embodiment also provides a positive electrode material, and the preparation method of the positive electrode material is exactly the same as that in Example 3.

Example 10

This embodiment provides a method for preparing nickel-cobalt-manganese hydroxide. The difference from Example 3 is that in step (3), the total molar weight of Ni, Co, Mn and Ta in the dispersion is equal to that of orthosilicate tetrachloride The molar ratio of Si in the ethyl ester was adjusted to 100:1.1, and the other operating steps were exactly the same as the process parameters and Example 3.

This embodiment also provides a positive electrode material, and the preparation method of the positive electrode material is exactly the same as that in Example 3.

Comparative example 1

This comparative example provides a kind of preparation method of nickel-cobalt-manganese hydroxide, and described preparation method specifically comprises the following steps:

(1) Using Ni(NO ₃ ) ₂ , Co(NO ₃ ) ₂ and Mn(NO ₃ ) ₂ to prepare metal solution A, wherein the total concentration of Ni, Co and Mn is 1.9mol/L, Ni, Co and Mn The molar ratio is 0.8:0.1:0.1; the preparation concentration is the sodium hydroxide solution of 11mol/L; the preparation concentration is the ammonia solution of 9mol/L;

(2) Inject appropriate amount of water, ammonia and liquid caustic soda into the reaction vessel, carry out sufficient stirring and mixing to prepare the bottom liquid, the pH of the bottom liquid is 11～12, then metal solution A, sodium hydroxide solution and ammonia The solutions are fed into the reaction container at the flow rate of 10L/h, 3.45L/h and 0.6L/h respectively, and the coprecipitation reaction is carried out under the conditions of pH 11.3-11.5 and temperature 70°C, and the coprecipitation reaction is under stirring. Carry out, the stirring speed is 420rpm, obtain nickel-cobalt-manganese hydroxide dispersion liquid after the reaction;

(3) Under the condition that the temperature is 70° C. and the stirring speed is 420 rpm, ethanol is added to the nickel-cobalt-manganese hydroxide matrix dispersion liquid, and then tetraethyl orthosilicate is added to control Ni, Co and The ratio of the total molar weight of Mn to the molar weight of Si in tetraethyl orthosilicate is 100:0.5, and the nickel-cobalt-manganese hydroxide is obtained through drying after the reaction.

This comparative example also provides a kind of positive electrode material, and the preparation method of described positive electrode material is as follows:

Mix nickel-cobalt-manganese hydroxide and lithium hydroxide and sinter at 750° C. for 8 hours to obtain the positive electrode material.

Comparative example 2

This comparative example provides a kind of preparation method of nickel-cobalt-manganese hydroxide, and the difference with embodiment 6 is, do not carry out step (3), directly centrifuge the dispersion liquid of Ta-doped nickel-cobalt-manganese hydroxide, wash and dry After that, nickel-cobalt-manganese hydroxide is obtained.

This comparative example also provides a kind of positive electrode material, and the preparation method of described positive electrode material is as follows:

Mix nickel-cobalt-manganese hydroxide and lithium hydroxide and sinter at 750° C. for 8 hours to obtain the positive electrode material.

Comparative example 3

This comparative example provides a kind of preparation method of nickel-cobalt-manganese hydroxide, and described preparation method specifically comprises the following steps:

(1) Using Ni(NO ₃ ) ₂ , Co(NO ₃ ) ₂ and Mn(NO ₃ ) ₂ to prepare metal solution A, wherein the total concentration of Ni, Co and Mn is 1.9mol/L, Ni, Co and Mn The molar ratio is 0.8:0.1:0.1; the preparation concentration is the sodium hydroxide solution of 11mol/L; the preparation concentration is the ammonia solution of 9mol/L;

(2) Inject appropriate amount of water, ammonia and liquid caustic soda into the reaction vessel, carry out sufficient stirring and mixing to prepare the bottom liquid, the pH of the bottom liquid is 11～12, then metal solution A, sodium hydroxide solution and ammonia The solutions are fed into the reaction container at the flow rate of 10L/h, 3.45L/h and 0.6L/h respectively, and the coprecipitation reaction is carried out under the conditions of pH 11.3-11.5 and temperature 70°C, and the coprecipitation reaction is under stirring. The stirring speed is 420rpm. After the reaction, a nickel-cobalt-manganese hydroxide dispersion is obtained. The nickel-cobalt-manganese hydroxide dispersion is centrifuged, washed and dried to obtain nickel-cobalt-manganese hydroxide.

This comparative example also provides a kind of positive electrode material, and the preparation method of described positive electrode material is as follows:

Mix nickel-cobalt-manganese hydroxide and lithium hydroxide and sinter at 750° C. for 8 hours to obtain the positive electrode material.

Comparative example 4

This comparative example provides a kind of preparation method of nickel-cobalt-manganese hydroxide, and described preparation method specifically comprises the following steps:

(1) Using Ni(NO ₃ ) ₂ , Co(NO ₃ ) ₂ and Mn(NO ₃ ) ₂ to prepare metal solution A, wherein the total concentration of Ni, Co and Mn is 1.9mol/L, Ni, Co and Mn The molar ratio of Ta is 0.8:0.1:0.1; The concentration of preparation Ta is the metal solution B of 0.08mol/L; The preparation concentration is the sodium hydroxide solution of 11mol/L; The preparation concentration is the ammonia solution of 9mol/L;

(2) Inject appropriate amount of water, ammonia and liquid caustic soda into the reaction vessel, carry out sufficient stirring and mixing to prepare the bottom liquid, the pH of the bottom liquid is 11～12, and then metal solution A, metal solution B, hydroxide Sodium solution and ammonia solution are fed into the reaction vessel in parallel with the flow rate of 10L/h, 0.8L/h, 3.45L/h and 0.6L/h respectively, and the total molar weight of Ni, Co and Mn in the metal solution A added is equal to The molar ratio of Ta in the metal solution B is 297:1, the co-precipitation reaction is carried out under the conditions of pH 11.3-11.5 and temperature 70°C, the co-precipitation reaction is carried out under stirring, and the stirring speed is 420rpm. After the reaction, The Ta-doped nickel-cobalt-manganese hydroxide dispersion liquid is centrifuged, washed and dried to obtain the Ta-doped nickel-cobalt-manganese hydroxide.

(3) Under the condition that the temperature is 70°C and the stirring speed is 420rpm, fully stir the Ta-doped nickel-cobalt-manganese hydroxide in the ethanol solution, and add an appropriate amount of ammonia solution with a concentration of 9mol/L, and then add Tetraethyl orthosilicate, control the ratio of the total molar weight of Ni, Co, Mn and Ta in the dispersion liquid to the molar weight of Si in tetraethyl orthosilicate to be 100:0.5, and obtain nickel-cobalt after drying manganese hydroxide.

This comparative example also provides a kind of positive electrode material, and the preparation method of described positive electrode material is as follows:

Mix nickel-cobalt-manganese hydroxide and lithium hydroxide and sinter at 750° C. for 8 hours to obtain the positive electrode material.

Performance Testing:

The cathode materials provided by Examples 1-10 and Comparative Examples 1-4 are combined with other parts to prepare lithium-ion batteries, and the preparation method is as follows: 80wt% of cathode materials, 10wt% of Super-P and 10wt% of Vinyl difluoride (PVDF) is thoroughly dispersed in N-methylpyrrolidone (NMP) solution to prepare electrode slurry, which is then further prepared into an electrode. The prepared electrode was used as the positive electrode, lithium metal was used as the negative electrode, a mixture of 1M LiPF ₆ and EC, DMC and EMC (EC: DMC: EMC = 1: 1: 1) was used as the electrolyte, Cellgard2300 was used as the separator, and CR2016 coin-shaped half cells were assembled. The process was carried out in an Ar-filled glove box.

Test conditions: the test is performed within a voltage window between 3.0-4.5V (vs Li/Li ⁺ ).

The test results are shown in Table 1.

Table 1

From the results of Example 3, Example 7 and Example 8, it can be seen that if the ratio of the total molar weight of Ni, Co and Mn in metal solution A to the molar weight of Ta in metal solution B is too low, nickel-cobalt-manganese-hydrogen The Ta doping content in the oxide matrix is too high. Since the Ta doping is mainly lithium doping, too much Ta will lead to poor ion conductivity of the material, and the prepared positive electrode material will show a lower capacity; if the ratio is too high If it is too high, the Ta doping content in the nickel-cobalt-manganese hydroxide matrix will be too low, too little Ta will not be able to effectively improve the structural stability of the material, resulting in poor structural stability of the material, and the prepared positive electrode material will show low capacity retention.

From the results of Example 3, Example 9 and Example 10, it can be seen that the ratio of the total molar weight of Ni, Co, Mn and Ta in the dispersion to the molar weight of Si in tetraethyl orthosilicate is too low, which will lead to inclusions. If the coating layer is too thick, it will inhibit the performance of the positive electrode material and have a low specific capacity; if the ratio is too high, the coating layer will be too thin, and the thin coating layer cannot effectively inhibit the boundary reaction, thereby reducing the electrochemical performance of the material. stability.

From the results of Example 6 and Comparative Examples 1-3, it can be seen that if the nickel-cobalt-manganese hydroxide matrix is not doped with Ta and only coated on the surface of the matrix, or only doped with Ta without coating, the prepared positive electrode material exhibits Poor cycle stability; the nickel-cobalt-manganese hydroxide prepared without doping and coating has poor structural stability, and the prepared positive electrode material shows poor cycle stability. However, the method provided by the present invention performs both Ta doping and coating, and the obtained nickel-cobalt-manganese hydroxide has more excellent structural stability and reliability, and the prepared positive electrode material exhibits high discharge capacity and excellent cycle stability. sex. This shows that the method of Ta doping and coating can jointly improve the structural stability of the material and improve the performance of the material.

From the results of Example 6 and Comparative Example 4, it can be seen that after preparing the Ta-doped nickel-cobalt-manganese hydroxide dispersion, compared with the method of wet coating after drying, directly using Ta-doped nickel-cobalt-manganese-hydrogen The alkaline environment of the oxide dispersion is wet-coated, and the obtained positive electrode material has excellent performance. This wet process has a continuous process, which can shorten the reaction time, improve production efficiency, and is more conducive to industrial production.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, and those skilled in the art should understand that any person skilled in the art should be aware of any disclosure in the present invention Within the technical scope, easily conceivable changes or substitutions all fall within the scope of protection and disclosure of the present invention.

Claims (10)

1. A preparation method of nickel-cobalt-manganese hydroxide is characterized by comprising the following steps:

(1) Adding a metal solution A containing Ni, co and Mn, a metal solution B containing Ta and an alkaline solution into the base solution in a concurrent flow manner, and carrying out a coprecipitation reaction to obtain a Ta-doped nickel-cobalt-manganese hydroxide matrix dispersion solution;

(2) Adding alcohols into the Ta doped nickel-cobalt-manganese hydroxide matrix dispersion liquid obtained in the step (1), adding silicates, and reacting to obtain the nickel-cobalt-manganese hydroxide.

2. The production method according to claim 1, wherein the alkaline solution includes a sodium hydroxide solution and an ammonia solution;

preferably, the flow ratio of the metal solution A, the metal solution B, the sodium hydroxide solution and the ammonia solution is 10 (0.16-3): 3.2-4.5): 0.3-0.7;

preferably, the metal solution a includes a Ni-containing compound, a Co-containing compound, and a Mn-containing compound;

preferably, the Ni-containing compound includes NiSO ₄ 、Ni(NO ₃ ) ₂ And NiCl ₂ At least one of;

preferably, the Co-containing compound comprises CoSO ₄ 、Co(NO ₃ ) ₂ And CoCl ₂ At least one of (a);

preferably, the Mn-containing compound includes MnSO ₄ 、Mn(NO ₃ ) ₂ And MnCl ₂ At least one of (a);

preferably, the total concentration of Ni, co and Mn in the metal solution A is 1.6-2.4 mol/L;

preferably, the molar ratio of Ni, co and Mn in the metal solution A is Ni: co: mn = x: y: z, wherein x + y + z =1, 0.6-n-1;

preferably, the metal solution B comprises NaTaO ₃ And/or NaTaO ₅ ；

Preferably, the concentration of Ta in the metal solution B is 0.04-0.1 mol/L;

preferably, the ratio of the total molar amount of Ni, co and Mn in the metal solution A to the molar amount of Ta in the metal solution B is (200-999): 1;

preferably, the concentration of the sodium hydroxide solution is 9-12 mol/L;

preferably, the concentration of the ammonia solution is 7-10 mol/L;

preferably, the base solution comprises water, ammonia and sodium hydroxide.

3. The production method according to claim 1 or 2, wherein the alcohol comprises at least one of methanol, ethanol, propanol and butanol;

preferably, the silicate comprises tetraethyl orthosilicate;

preferably, the ratio of the total molar amount of Ni, co and Mn in the Ta-doped nickel-cobalt-manganese hydroxide matrix dispersion liquid to the molar amount of Si in the silicate ester is 100 (0.5-1).

4. The production method according to any one of claims 1 to 3, wherein during the coprecipitation reaction in step (1), the pH is controlled to be in the range of 10 to 13;

preferably, in the coprecipitation reaction process in the step (1), the temperature is controlled within the range of 40-70 ℃;

preferably, the coprecipitation reaction in step (1) is carried out under stirring, and the stirring speed is 250-420 rpm.

5. The production method according to any one of claims 1 to 4, wherein during the reaction in the step (2), the temperature is controlled in the range of 40 to 70 ℃;

preferably, the reaction in the step (2) is carried out under stirring, and the stirring speed is 250-420 rpm.

6. The preparation method according to any one of claims 1 to 5, comprising in particular the steps of:

preparing a metal solution A with the total concentration of Ni, co and Mn of 1.6-2.4 mol/L, wherein the molar ratio of Ni to Co to Mn = x to y to z, wherein x + y + z =1, and 0.6-x-cloth-1;

preparing a metal solution B with the concentration of Ta of 0.04-0.1 mol/L;

preparing a sodium hydroxide solution with the concentration of 9-12 mol/L;

preparing ammonia solution with the concentration of 7-10 mol/L;

(II) preparing a base solution in a reaction container, and adding a metal solution A, a metal solution B, a sodium hydroxide solution and an ammonia solution in parallel according to a flow ratio of (0.16-3) to (3.2-4.5) to (0.3-0.7) to perform a coprecipitation reaction to obtain a Ta-doped nickel-cobalt-manganese hydroxide dispersion solution;

(III) adding alcohols into the Ta-doped nickel-cobalt-manganese hydroxide matrix dispersion liquid, adding silicates, and reacting to obtain the nickel-cobalt-manganese hydroxide.

7. A nickel cobalt manganese hydroxide, wherein the nickel cobalt manganese hydroxide is prepared by the preparation method of claims 1 to 6;

preferably, the nickel-cobalt-manganese hydroxide comprises a Ta-doped nickel-cobalt-manganese hydroxide substrate and a silicon-oxygen coating layer coated on the surface of the Ta-doped nickel-cobalt-manganese hydroxide substrate.

8. A nickel cobalt manganese hydroxide according to claim 7 characterised in that the amount of Ta doped in the Ta doped nickel cobalt manganese hydroxide matrix is from 2000 to 10000ppm, preferably from 2000 to 5000ppm;

preferably, the thickness of the silicon oxide coating layer is 2-14 nm.

9. A positive electrode material obtained by mixing and sintering the nickel-cobalt-manganese hydroxide according to claim 7 or 8 with a lithium source;

preferably, the positive electrode material comprises a nickel cobalt lithium manganate substrate and a lithiated silicon oxygen coating layer coated on the surface of the nickel cobalt lithium manganate substrate;

preferably, the sintering temperature is 700-900 ℃;

preferably, the sintering time is 5-15 h.

10. A lithium ion battery comprising the positive electrode material according to claim 9 in a positive electrode.