阅读说明：本技术 一种钨掺杂高镍无钴前驱体及其制备方法 (Tungsten-doped high-nickel cobalt-free precursor and preparation method thereof ) 是由 陈旭东 徐乾松 马娇 于 2021-06-30 设计创作，主要内容包括：本发明提供了一种钨掺杂高镍无钴前驱体,其特征在于,所述钨掺杂高镍无钴前驱体的化学式为Ni-(a)Mn-(b)R-(1-a-b)(OH)-(2-2c)(WO-(4))-(c)；其中,0.9≤a<1.0,0<b<0.1,0<c≤0.1；R为Mg、Ca、Al、Ti、Zr、Zn、Ba与Sr中的一种或多种。与现有技术相比,本发明利用廉价金属元素替代钴元素,可在保证高镍材料容量的同时,提升了材料的稳定性,并且本发明得到钨均匀掺杂且具有稳定结构的高镍无钴前驱体,不仅改善了高镍前驱体普遍存在的二次球裂纹问题,且二次颗粒球形度和尺寸一致性也良好,表面一次晶须均匀,并具有多孔结构,混合锂源后所得高镍无钴正极材料在保证容量的基础上具有良好的循环稳定性。(The invention provides a tungsten-doped high-nickel cobalt-free precursor which is characterized by having a chemical formula of Ni a Mn b R 1‑a‑b (OH) 2‑2c (WO 4 ) c (ii) a Wherein, a is more than or equal to 0.9<1.0，0<b<0.1，0<c is less than or equal to 0.1; r is one or more of Mg, Ca, Al, Ti, Zr, Zn, Ba and Sr. Compared with the prior art, the invention utilizes cheap metal elements to replace cobalt elements, can ensure the capacity of the high-nickel material and simultaneously improve the stability of the material, and tungsten is uniformly doped and has stabilityThe high-nickel cobalt-free precursor has the advantages that the problem of secondary ball cracks of the high-nickel precursor generally existing is solved, the sphericity and size consistency of secondary particles are good, primary whiskers on the surface are uniform, the high-nickel cobalt-free precursor is of a porous structure, and the high-nickel cobalt-free anode material obtained after a lithium source is mixed has good circulation stability on the basis of capacity guarantee.)

1. The precursor is characterized in that the chemical formula of the precursor is Ni_aMn_bR_1-a-b(OH)_2-2c(WO₄)_c；

Wherein a is more than or equal to 0.9 and less than 1.0, b is more than 0 and less than 0.1, and c is more than 0 and less than or equal to 0.1;

r is one or more of Mg, Ca, Al, Ti, Zr, Zn, Ba and Sr.

2. A method for preparing the tungsten-doped high-nickel cobalt-free precursor of claim 1, comprising:

s1) in a protective atmosphere, mixing and reacting nickel salt, manganese salt, R salt, tungstate, a complexing agent and a precipitator in water to obtain tungsten-doped high-nickel cobalt-free precursor mixed slurry;

s2) ageing the mixed slurry of the tungsten-doped high-nickel cobalt-free precursor to obtain the tungsten-doped high-nickel cobalt-free precursor.

3. The preparation method according to claim 2, wherein the concentration of the complexing agent in the step S1) is kept at 0.1-2 mol/L during the mixing reaction; and keeping the pH value of the reaction liquid to be 9-13 in the mixing reaction process.

4. The preparation method according to claim 2, wherein the step S1) is specifically:

A) adding nickel salt, manganese salt and R salt in the form of mixed salt solution; tungstate, a complexing agent and a precipitator are all added in the form of aqueous solution;

mixing a complexing agent aqueous solution, a precipitator aqueous solution and water to obtain a reaction base solution;

B) and in a protective atmosphere, adding the mixed salt solution and the tungstate solution into the reaction base solution for reaction, and simultaneously adding a complexing agent aqueous solution and a precipitator aqueous solution to control the pH value of the reaction solution and the concentration of the complexing agent, thereby obtaining the tungsten-doped high-nickel cobalt-free precursor mixed slurry.

5. The preparation method according to claim 4, wherein the concentration of the aqueous solution of the complexing agent is 5-13 mol/L; the concentration of the precipitant aqueous solution is 5-15 mol/L; the total concentration of metal ions in the mixed salt solution is 0.5-2 mol/L; the concentration of the tungsten element in the tungstate solution is 0.01-0.5 mol/L.

6. The preparation method according to claim 4, wherein the flow rate of the mixed salt solution added in the step B) is 20 to 200 mL/min; the flow rate of adding the tungstate solution is 5-40 mL/min; the flow rate of adding the complexing agent aqueous solution is 1-20 mL/min; the flow rate of the precipitant aqueous solution is 10-60 mL/min.

7. The preparation method according to claim 4, wherein the temperature of the reaction in the step B) is 40-80 ℃; the reaction is carried out under the condition of stirring; the rotating speed of the stirring is 600-1200 rpm; the aging temperature is 40-80 ℃; the aging time is 30-90 min.

8. The preparation method according to claim 2, wherein the tungsten-doped high-nickel cobalt-free precursor is obtained after aging in step S2), washing with water, filtering, drying and sieving; the temperature of the washing water is 40-80 ℃; the sieved screen is a 200-400 mesh screen.

9. The method according to claim 2, wherein the nickel salt is selected from one or more of a sulfate, a halide and a nitrate of nickel; the manganese salt is selected from one or more of sulfate, halide and nitrate of manganese; the R salt is selected from one or more of sulfate, halide and nitrate of R; the tungstate is selected from one or more of sodium tungstate, potassium tungstate, ammonium metatungstate and ammonium phosphotungstate; the complexing agent is selected from one or more of ammonia water, ammonium bicarbonate, ethylene diamine tetraacetic acid, glycine and triethanolamine; the precipitant is selected from one or more of lithium hydroxide, sodium hydroxide, potassium hydroxide and sodium carbonate.

10. A positive electrode material, which is prepared from the tungsten-doped high-nickel cobalt-free precursor of claim 1 or the tungsten-doped high-nickel cobalt-free precursor prepared by the preparation method of any one of claims 2 to 9 and a lithium source.

Technical Field

The invention belongs to the technical field of lithium ion battery materials, and particularly relates to a tungsten-doped high-nickel cobalt-free precursor and a preparation method thereof.

Background

In the current lithium ion battery cathode material, a high nickel material has high energy density, but the defects are obvious, the structural stability and the high temperature stability of the high nickel material are poor, the phase change of particles on the surface is easy to occur, the particles are gradually converted into a spinel structure and a rock salt structure from a layered structure, the conversion process is not reversible, the phase change on the surface can extend to the inside of the particles, so that the particles generate cracks in the charging and discharging processes to cause the material to lose efficacy, and particularly when the molar content of nickel is more than 90%, the defects are more obvious.

Proper amount of tungsten doping can stably improve the working voltage of the lithium ion battery and ensure the energy density of the battery; the distance between the layered structures is increased, and the multiplying power performance is improved; and the crystal structure of the precursor is stabilized, so that the cycle stability of the cathode material is enhanced.

At present, the tungsten-doped anode material is synthesized by adding a tungsten source while sintering a precursor and a lithium source mainly through a high-temperature solid phase method. But due to WO₃The melting point is high, the existing sintering temperature needs to be greatly increased, and the energy consumption and equipment requirements are greatly increased. Therefore, the tungsten is doped in the precursor synthesis stage, so that the stability of the material can be improved, and the cost can be effectively reduced.

Meanwhile, cobalt in the anode material mainly has the functions of improving the crystal conductivity and stabilizing the structure, but because cobalt is deficient in natural resources, expensive in price and greatly influenced by the market, the cobalt is not suitable for long-term large-scale use. Therefore, Mg, Ca, Al, Ti, Zr, Zn, Ba, Sr, La, Nd, Eu, Nb, Pr, Yb, Lu, Sn, Mo and other elements can be adopted to replace the cobalt element to play a role in the cathode material.

Therefore, in the precursor synthesis stage, one or more elements are searched for to replace cobalt element, and can be uniformly doped with tungsten element, so that the improvement of the stability of the high-nickel cathode material is of great importance.

Disclosure of Invention

In view of the above, the technical problem to be solved by the present invention is to provide a tungsten uniformly doped high nickel cobalt-free precursor with good particle sphericity and size uniformity, uniform primary whiskers on the surface, and a porous structure, and a preparation method thereof, wherein the precursor material has good cycling stability after being fired into a positive electrode material.

The invention provides a tungsten-doped high-nickel cobalt-free precursor, which has a chemical formula of Ni_aMn_bR_1-a-b(OH)_2-2c(WO₄)_c；

Wherein a is more than or equal to 0.9 and less than 1.0, b is more than 0 and less than 0.1, and c is more than 0 and less than or equal to 0.1;

r is one or more of Mg, Ca, Al, Ti, Zr, Zn, Ba and Sr.

The invention also provides a preparation method of the tungsten-doped high-nickel cobalt-free precursor, which comprises the following steps:

s1) in a protective atmosphere, mixing and reacting nickel salt, manganese salt, R salt, tungstate, a complexing agent and a precipitator in water to obtain tungsten-doped high-nickel cobalt-free precursor mixed slurry;

s2) ageing the mixed slurry of the tungsten-doped high-nickel cobalt-free precursor to obtain the tungsten-doped high-nickel cobalt-free precursor.

Preferably, the concentration of the complexing agent in the step S1) is kept to be 0.1-2 mol/L in the mixing reaction process; and keeping the pH value of the reaction liquid to be 9-13 in the mixing reaction process.

Preferably, the step S1) is specifically:

A) adding nickel salt, manganese salt and R salt in the form of mixed salt solution; tungstate, a complexing agent and a precipitator are all added in the form of aqueous solution;

mixing a complexing agent aqueous solution, a precipitator aqueous solution and water to obtain a reaction base solution;

B) and in a protective atmosphere, adding the mixed salt solution and the tungstate solution into the reaction base solution for reaction, and simultaneously adding a complexing agent aqueous solution and a precipitator aqueous solution to control the pH value of the reaction solution and the concentration of the complexing agent, thereby obtaining the tungsten-doped high-nickel cobalt-free precursor mixed slurry.

Preferably, the concentration of the complexing agent aqueous solution is 5-13 mol/L; the concentration of the precipitant aqueous solution is 5-15 mol/L; the total concentration of metal ions in the mixed salt solution is 0.5-2 mol/L; the concentration of the tungsten element in the tungstate solution is 0.01-0.5 mol/L.

Preferably, the flow rate of the mixed salt solution added in the step B) is 20-200 mL/min; the flow rate of adding the tungstate solution is 5-40 mL/min; the flow rate of adding the complexing agent aqueous solution is 1-20 mL/min; the flow rate of the precipitant aqueous solution is 10-60 mL/min.

Preferably, the reaction temperature in the step B) is 40-80 ℃; the reaction is carried out under the condition of stirring; the rotating speed of the stirring is 600-1200 rpm; the aging temperature is 40-80 ℃; the aging time is 30-90 min.

Preferably, the precursor is aged in the step S2), washed with water, filtered, dried and sieved to obtain a tungsten-doped high-nickel cobalt-free precursor; the temperature of the washing water is 40-80 ℃; the sieved screen is a 200-400 mesh screen.

Preferably, the nickel salt is selected from one or more of sulfate, halide and nitrate of nickel; the manganese salt is selected from one or more of sulfate, halide and nitrate of manganese; the R salt is selected from one or more of sulfate, halide and nitrate of R; the tungstate is selected from one or more of sodium tungstate, potassium tungstate, ammonium metatungstate and ammonium phosphotungstate; the complexing agent is selected from one or more of ammonia water, ammonium bicarbonate, ethylene diamine tetraacetic acid, glycine and triethanolamine; the precipitant is selected from one or more of lithium hydroxide, sodium hydroxide, potassium hydroxide and sodium carbonate.

The invention also provides a positive electrode material prepared from the tungsten-doped high-nickel cobalt-free precursor and a lithium source.

The invention provides a tungsten-doped high-nickel cobalt-free precursor, which has a chemical formula of Ni_aMn_bR_1-a-b(OH)_2-2c(WO₄)_c(ii) a Wherein, a is more than or equal to 0.9<1.0，0<b<0.1，0<c is less than or equal to 0.1; r is one or more of Mg, Ca, Al, Ti, Zr, Zn, Ba and Sr. Compared with the prior art, the invention utilizes cheap metal elements to replace cobalt elements, can ensure the capacity of the high-nickel material, simultaneously improves the stability of the material, and reduces the raw materialsThe high-nickel cobalt-free precursor with uniformly doped tungsten and a stable structure is obtained, the problem of secondary spherical cracks commonly existing in the high-nickel precursor is solved, the sphericity and the size consistency of secondary particles are good, primary whiskers on the surface are uniform, the high-nickel cobalt-free precursor is of a porous structure, and the high-nickel cobalt-free cathode material obtained after a lithium source is mixed has good cycling stability on the basis of ensuring the capacity.

Drawings

FIG. 1 is a schematic view of a reaction vessel and a liquid feeding method used in example 1 of the present invention;

FIG. 2 is a scanning electron microscope image of a tungsten-doped high-nickel cobalt-free precursor obtained in example 1 of the present invention;

FIG. 3 is a Scanning Electron Microscope (SEM) cross-section of the W-doped high-Ni cobalt-free precursor obtained in example 1 of the present invention;

FIG. 4 is a cross-sectional EDS-mapping chart of the tungsten-doped high-nickel cobalt-free precursor obtained in example 1 of the present invention;

fig. 5 is a graph of the full-electric charge-discharge cycle performance of the positive electrode material prepared from the tungsten-doped high-nickel cobalt-free precursor obtained in embodiments 1 to 3 of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a tungsten-doped high-nickel cobalt-free precursor, which has a chemical formula of Ni_aMn_bR_1-a-b(OH)_2-2c(WO₄)_c；

Wherein 0.9. ltoreq. a <1.0, preferably 0.9. ltoreq. a.ltoreq.0.99, more preferably 0.9. ltoreq. a.ltoreq.0.98, still more preferably 0.92. ltoreq. a.ltoreq.0.98, most preferably 0.94. ltoreq. a.ltoreq.0.98; 0< b <0.1, preferably 0.01. ltoreq. b < 0.1; c is more than 0 and less than or equal to 0.1; in the examples provided by the present invention, specifically, a is 0.96 and b is 0.02.

R is one or more of Mg, Ca, Al, Ti, Zr, Zn, Ba and Sr.

The method utilizes cheap metal elements to replace cobalt elements, can ensure the capacity of the high-nickel material, simultaneously improves the stability of the material, reduces the cost of raw materials, obtains the high-nickel cobalt-free precursor with uniformly doped tungsten and a stable structure, improves the ubiquitous problem of secondary ball cracks of the high-nickel precursor, has good sphericity and size consistency of secondary particles, uniform primary whiskers on the surface and has a porous structure.

The invention also provides a preparation method of the tungsten-doped high-nickel cobalt-free precursor, which comprises the following steps: s1) in a protective atmosphere, mixing and reacting nickel salt, manganese salt, R salt, tungstate, a complexing agent and a precipitator in water to obtain tungsten-doped high-nickel cobalt-free precursor mixed slurry; s2) ageing the mixed slurry of the tungsten-doped high-nickel cobalt-free precursor to obtain the tungsten-doped high-nickel cobalt-free precursor.

In the present invention, the sources of all raw materials are not particularly limited, and they may be commercially available.

In the invention, the nickel salt is a soluble salt of nickel, preferably one or more of sulfate, halide and nitrate of nickel, more preferably one or more of nickel sulfate, nickel chloride and nickel nitrate; the manganese salt is soluble salt of manganese, preferably one or more of sulfate, halide and nitrate of manganese, more preferably one or more of manganese sulfate, manganese chloride and manganese nitrate; the R salt is a soluble salt of R, preferably one or more of sulfate, halide and nitrate of R, and more preferably one or more of sulfate, chloride and nitrate of R; the tungstate is preferably one or more of sodium tungstate, potassium tungstate, ammonium metatungstate and ammonium phosphotungstate; the complexing agent is preferably one or more of ammonia water, ammonium bicarbonate, ethylene diamine tetraacetic acid, glycine and triethanolamine; the precipitant is preferably one or more of lithium hydroxide, sodium hydroxide, potassium hydroxide and sodium carbonate.

Mixing and reacting nickel salt, manganese salt, R salt, tungstate, complexing agent and precipitator in water in protective atmosphere; in the present invention, the above raw materials are all preferably added in the form of an aqueous solution, and more preferably specifically: A) adding nickel salt, manganese salt and R salt in the form of mixed salt solution; tungstate, a complexing agent and a precipitator are all added in the form of aqueous solution; mixing a complexing agent aqueous solution, a precipitator aqueous solution and water to obtain a reaction base solution; B) and in a protective atmosphere, adding the mixed salt solution and the tungstate solution into the reaction base solution for reaction, and simultaneously adding a complexing agent aqueous solution and a precipitator aqueous solution to control the pH value of the reaction solution and the concentration of the complexing agent, thereby obtaining the tungsten-doped high-nickel cobalt-free precursor mixed slurry.

Wherein the total concentration of metal ions in the mixed salt solution is preferably 0.5-2 mol/L, more preferably 1-2 mol/L, and still more preferably 1.5 mol/L; the molar ratio of nickel element, manganese element and R tuple in the mixed salt solution is a: b: (1-a-b); the concentration of the tungsten element in the tungstate solution is preferably 0.01-0.5 mol/L, more preferably 0.05-0.3 mol/L, still more preferably 0.1-0.2 mol/L, and most preferably 0.15 mol/L; the concentration of the complexing agent aqueous solution is preferably 5-13 mol/L, more preferably 6-12 mol/L, further preferably 8-10 mol/L, and most preferably 9 mol/L; the concentration of the precipitant aqueous solution is preferably 5-15 mol/L, more preferably 5-13 mol/L, and still more preferably 5-10 mol/L.

Mixing a complexing agent aqueous solution, a precipitator aqueous solution and water to obtain a reaction base solution; the pH value of the reaction bottom liquid is preferably 9-13, more preferably 10-13, further preferably 11-13, and most preferably 11.6-12; in the embodiment provided by the invention, the pH value of the reaction base solution is specifically 12, 11.8 or 11.6; the concentration of the complexing agent in the reaction bottom liquid is preferably 0.1-2 mol/L, more preferably 0.1-1.5 mol/L, still more preferably 0.1-1 mol/L, still more preferably 0.2-0.8 mol/L, and most preferably 0.3-0.6 mol/L.

In a protective atmosphere, adding the mixed salt solution and a tungstate solution into the reaction base solution for reaction; the protective atmosphere is preferably nitrogen; in the present invention, it is preferable to continuously introduce a protective atmosphere during the reaction; the flow rate of the protective atmosphere is preferably 0.1-0.8 m³More preferably 0.1 to 0.6 m/h³A, more preferably 0.2 to 0.5m³A/h, most preferably 0.3 to 0.5m³H; the flow rate of the mixed salt solution is preferably 20-200 mL/min, more preferably 20-150 mL/min, still more preferably 30-100 mL/min, still more preferably 40-80 mL/min, and most preferably 50 mL/min; the flow rate of adding the tungstate solution is preferably 5-40 mL/min, more preferably 5-30 mL/min, further preferably 5-20 mL/min, and most preferably 5-10 mL/min; the reaction temperature is preferably 40-80 ℃, more preferably 50-70 ℃, and further preferably 55-65 ℃; the reaction is preferably carried out under stirring; the rotating speed of the stirring is preferably 600-1200 rpm, and more preferably 800-1200 rpm; in the embodiment provided by the invention, the rotating speed of the stirring is 1000 rpm.

Adding a complexing agent aqueous solution and a precipitator aqueous solution to control the pH value of the reaction solution and the concentration of the complexing agent during the reaction; the flow rate of adding the complexing agent aqueous solution is preferably 1-20 mL/min; the flow rate of adding the precipitant aqueous solution is preferably 10-60 mL/min; the adding amount of the complexing agent aqueous solution and the precipitating agent aqueous solution is preferably selected to ensure that the pH value of the reaction solution is 9-13, more preferably 10-13, still more preferably 10.5-13, and most preferably 10.7-12; in the embodiment provided by the invention, the adding amount of the aqueous solution of the complexing agent and the aqueous solution of the precipitating agent is specifically such that the pH value of the reaction solution is 11.4, 10.9 or 10.7; the concentration of the complexing agent in the reaction solution is preferably 0.1 to 2mol/L, more preferably 0.1 to 1.5mol/L, still more preferably 0.3 to 1mol/L, and most preferably 0.3 to 0.5 mol/L; in the embodiment provided by the present invention, the concentration of the complexing agent in the reaction solution is specifically 0.3 to 0.5mol/L or 0.8 to 1.0 mol/L.

In the present invention, the above reaction is preferably carried out in a reaction vessel; the volume of water used for preparing the reaction bottom liquid is preferably 70-80% of the effective volume of the reaction kettle; all the raw materials are added into a reaction kettle through a liquid inlet pipe; according to the invention, the high-nickel cobalt-free precursor with tungsten uniformly doped and stable crystal structure is synthesized by controlling the arrangement of the outlet positions of the raw material liquid inlet pipes, so that the problem of secondary ball cracks commonly existing in the high-nickel precursor is solved, the sphericity and the size consistency of secondary particles are good, primary whiskers on the surface are uniform, and the high-nickel cobalt-free precursor has a porous structure; in the invention, preferably, liquid inlet pipes of a complexing agent aqueous solution, a precipitator aqueous solution and a tungstate aqueous solution are arranged on one side of a reaction kettle, and a liquid inlet pipe of a mixed salt solution is arranged on the other opposite side; the outlets of the liquid inlet pipes of the precipitant aqueous solution, the complexing agent aqueous solution and the mixed salt solution are positioned near the second-stage stirring paddle of the reaction kettle, namely below the liquid level of the reaction liquid; the outlet of the tungstate aqueous solution inlet pipe is positioned above the liquid level of the reaction liquid, as shown in figure 1.

In the invention, the reaction is preferably carried out for 65-70 h, and the feeding is stopped when the granularity D50 of the product in the reaction liquid reaches about 6 mu m, so as to obtain the tungsten-doped high-nickel cobalt-free precursor mixed slurry.

Aging the tungsten-doped high-nickel cobalt-free precursor mixed slurry; the temperature of the aging is preferably 40-80 ℃, more preferably 50-70 ℃, and further preferably 55-60 ℃; the aging is preferably carried out under stirring; the rotating speed of the stirring is preferably 600-1200 rpm, and more preferably 800-1200 rpm; in the embodiment provided by the invention, the rotating speed of the stirring is specifically 1000 rpm; the aging time is preferably 30-90 min, more preferably 40-80 min, still more preferably 50-70 min, and most preferably 60 min.

After aging, preferably washing with water, filtering, drying and sieving; the temperature of the washing water is preferably 40-80 ℃, more preferably 50-70 ℃, and further preferably 60-65 ℃; the drying temperature is preferably 90-150 ℃, more preferably 100-140 ℃, and further preferably 120-130 ℃; the drying time is preferably 10-20 h, more preferably 12-18 h, and further preferably 15-16 h; the sieve is preferably 200-400 mesh.

And after sieving, preferably removing iron to obtain the tungsten-doped high-nickel cobalt-free precursor.

Soluble metal salt replacing cobalt is mixed with soluble metal salt of nickel and manganese, the mixture and soluble tungstate are respectively added into a reaction kettle, reaction conditions are controlled, the mixed metal ion and tungsten are coprecipitated, tungstate radicals generated by tungstate ionization can generate precipitation with the mixed metal ion, and therefore the coprecipitation of the mixed metal ion and tungsten can be realized under the condition that other precipitating agents are not added; meanwhile, in the preparation process, by controlling reaction conditions and a liquid inlet mode of a complexing agent, a precipitator and metal salt, a tungsten-doped high-nickel cobalt-free precursor can be obtained after the processes of synthesis, aging, washing, drying, sieving, iron removal and the like, and the high-nickel cobalt-free precursor which is uniformly doped with tungsten and has a stable crystal structure is obtained, so that the problem of secondary spherical cracks commonly existing in the high-nickel precursor is solved, the sphericity and the size consistency of secondary particles are good, primary whiskers on the surface are uniform, and the precursor has a porous structure; moreover, the preparation method is simple, only needs to slightly improve the existing conventional ternary precursor synthesis reaction equipment, and effectively reduces the production cost.

The invention also provides a positive electrode material prepared from the tungsten-doped high-nickel cobalt-free precursor and a lithium source.

In the invention, the preparation method specifically comprises the following steps: and mixing the tungsten-doped high-nickel cobalt-free precursor with a lithium source, and then carrying out secondary calcination treatment in an oxygen atmosphere to obtain the cathode material. The secondary calcination treatment specifically comprises the following steps: calcining for 20-30 hours at 500-900 ℃ for the first time, and calcining for 15-25 hours at 600-800 ℃ for the second time.

In order to further illustrate the present invention, the tungsten-doped high-nickel cobalt-free precursor and the preparation method thereof provided by the present invention are described in detail below with reference to the examples.

The reagents used in the following examples are all commercially available.

Example 1

1.1 preparing a solution A with the concentration of an ammonia water complexing agent being 9mol/L by using deionized water; deionized water is used for preparing a solution B with the concentration of 5mol/L of sodium hydroxide precipitator.

1.2 preparing a solution C with the total concentration of three ions of Ni, Mn and Mg of 1.5mol/L by using deionized water, nickel sulfate, manganese sulfate and magnesium sulfate, wherein the ratio of Ni: mn: mg molar ratio 96: 2: 2; preparation of WO from deionized water and sodium tungstate₄Solution D with an ion concentration of 0.15 mol/L.

1.3 adding 80L of deionized water into a 100L reaction kettle, introducing the solution A and the solution B to prepare a base solution E with the pH value of 12.0 and the ammonia concentration of 0.3mol/L, controlling the temperature of the base solution to be 55 ℃ and the stirring speed to be 1000 rpm.

1.4 to the reaction kettle with a volume of 0.3m³Introducing nitrogen at a flow rate of per hour, and introducing the solution A, B, C, D into the reaction kettle through a precision constant flow pump according to a liquid inlet mode shown in the figure 1, wherein the stable flow rate of the solution C is 50 mL/min; the steady flow rate of solution D was 10 mL/min. Controlling the pH value to be 11.4, the ammonia concentration to be 0.3-0.5 mol/L and the temperature to be 55 ℃ in the reaction process, and continuously introducing nitrogen in the reaction process.

1.5, maintaining the reaction time for 65-70 h, stopping feeding until the granularity D50 of the material in the reaction kettle reaches about 6.0 mu m to obtain mixed slurry F, continuously stirring for 60min, discharging, washing with deionized water at 55 ℃, centrifuging, drying in an air-blast drying oven at 120 ℃ for 15h until the water content reaches the requirement, sieving by using a 400-mesh sieve, and removing iron to obtain the tungsten-doped high-nickel cobalt-free precursor.

Analyzing the tungsten-doped high-nickel cobalt-free precursor obtained in the example 1 by using a scanning electron microscope to obtain a surface scanning electron microscope image, which is shown in fig. 2; obtaining a cross-sectional scanning electron microscope image of the sample, as shown in FIG. 3; the EDS-mapping profile of the obtained section is shown in FIG. 4.

Example 2

2.1 preparing a solution A with the concentration of an ammonia water complexing agent being 7mol/L by using deionized water; deionized water is used for preparing a solution B with the concentration of 5mol/L of sodium hydroxide precipitator.

2.2 preparing a solution C with the total concentration of three ions of Ni, Mn and Ti of 1.5mol/L by using deionized water and nickel sulfate, manganese sulfate and titanium sulfate, wherein the ratio of Ni: mn: ti molar ratio 96: 2: 2; preparation of WO from deionized water and ammonium tungstate₄Solution D with an ion concentration of 0.15 mol/L.

2.3 Add 80L deionized water into 100L reactor, fill in solution A and B, make into the base solution E with pH 11.8, ammonia concentration 0.3mol/L, control the base solution temperature to 55 deg.C, the stirring speed is 1000 rpm.

2.4 to the reaction kettle at a speed of 0.3m³Introducing nitrogen at a flow rate of per hour, and introducing the solution A, B, C, D into the reaction kettle through a precision constant flow pump according to a liquid inlet mode shown in the figure 1, wherein the stable flow rate of the solution C is 50 mL/min;the steady flow rate of solution D was 10 mL/min. Controlling the pH value to be 10.9, the ammonia concentration to be 0.3-0.5 mol/L and the temperature to be 65 ℃ in the reaction process, and continuously introducing nitrogen in the reaction process.

2.5, maintaining the reaction time for 65-70 h, stopping feeding until the granularity D50 of the materials in the reaction kettle reaches about 6.0 mu m to obtain mixed slurry F, continuously stirring for 60min, discharging, washing with deionized water at 65 ℃, centrifuging, drying in an air-blast drying oven at 120 ℃ for 15h until the water content reaches the requirement, sieving by using a 400-mesh sieve, and removing iron to obtain the tungsten-doped high-nickel cobalt-free precursor.

Example 3

3.1 preparing a solution A with the concentration of an ammonium bicarbonate complexing agent of 9mol/L by using deionized water; deionized water is used for preparing a solution B with the concentration of 2.5mol/L of carbonic acid precipitant.

3.2 preparing a solution C with the total concentration of three ions of Ni, Mn and Al of 1.5mol/L by using deionized water and nickel chloride, manganese chloride and aluminum chloride, wherein the ratio of Ni: mn: al 96: 2: 2; preparation of WO with deionized water and ammonium tungstate₄Solution D with an ion concentration of 0.15 mol/L.

3.3 Add 80L deionized water into 100L reactor, fill in solution A and B, make into the base solution E with pH 11.6, ammonia concentration 0.6mol/L, control the base solution temperature to 65 deg.C, the stirring speed is 1000 rpm.

3.4 to the reaction kettle with a volume of 0.3m³Introducing nitrogen at a flow rate of per hour, and introducing the solution A, B, C, D into the reaction kettle through a precision constant flow pump according to a liquid inlet mode shown in the figure 1, wherein the stable flow rate of the solution C is 50 mL/min; the steady flow rate of solution D was 10 mL/min. Controlling the pH value to be 10.7, the ammonia concentration to be 0.8-1.0 mol/L and the temperature to be 65 ℃ in the reaction process, and continuously introducing nitrogen in the reaction process.

3.5, maintaining the reaction time for 65-70 h, stopping feeding until the granularity D50 of the materials in the reaction kettle reaches about 6.0 mu m to obtain mixed slurry F, continuously stirring for 60min, discharging, washing with deionized water at 55 ℃, centrifuging, drying in an air-blast drying oven at 120 ℃ for 15h until the water content reaches the requirement, sieving by using a 400-mesh sieve, and removing iron to obtain the tungsten-doped high-nickel cobalt-free precursor.

Comparative example 1

1.1 preparing a solution A with the concentration of an ammonia water complexing agent being 9mol/L by using deionized water; deionized water is used for preparing a solution B with the concentration of 5mol/L of sodium hydroxide precipitator.

1.2 preparing a solution C with the total concentration of three ions of Ni, Mn and Mg of 1.5mol/L by using deionized water, nickel sulfate, manganese sulfate and magnesium sulfate, wherein the ratio of Ni: mn: mg molar ratio 96: 2: 2.

1.3 adding 80L of deionized water into a 100L reaction kettle, introducing the solution A and the solution B to prepare a base solution D with the pH value of 12.0 and the ammonia concentration of 0.3mol/L, controlling the temperature of the base solution to be 55 ℃ and the stirring speed to be 1000 rpm.

1.4 to the reaction kettle with a volume of 0.3m³Introducing nitrogen at a flow rate of/h, introducing the solution A, B, C into the reaction kettle by a precision constant flow pump according to a liquid inlet mode shown in figure 1, wherein the stable flow rate of the solution C is 50mL/min, a liquid inlet pipe of soluble salt containing the W element is not used, and sealing the liquid inlet pipe. Controlling the pH value to be 11.4, the ammonia concentration to be 0.3-0.5 mol/L and the temperature to be 55 ℃ in the reaction process, and continuously introducing nitrogen in the reaction process.

1.5, maintaining the reaction time for 65-70 h, stopping feeding until the granularity D50 of the materials in the reaction kettle reaches about 6.0 mu m to obtain mixed slurry E, continuously stirring for 60min, discharging, washing with deionized water at 55 ℃, centrifuging, drying in a blast drying oven at 120 ℃ for 15h until the water content reaches the requirement, sieving by using a 400-mesh sieve, and removing iron to obtain the high-nickel cobalt-free precursor.

Comparative example 2

2.1 preparing a solution A with the concentration of an ammonia water complexing agent being 7mol/L by using deionized water; deionized water is used for preparing a solution B with the concentration of 5mol/L of sodium hydroxide precipitator.

2.2 preparing a solution C with the total concentration of three ions of Ni, Mn and Ti of 1.5mol/L by using deionized water and nickel sulfate, manganese sulfate and titanium sulfate, wherein the ratio of Ni: mn: ti molar ratio 96: 2: 2.

2.3 Add 80L deionized water into 100L reactor, fill in solution A and B, make into base solution D with pH 11.8 and ammonia concentration of 0.3mol/L, control the temperature of base solution at 55 deg.C, stir speed at 1000 rpm.

2.4 to the reaction kettle at a speed of 0.3m³Introducing nitrogen at a flow rate of/h, and feeding the solution A, B, C into a precision constant flow pump according to the liquid feeding method shown in figure 1And (3) introducing the solution C into the reaction kettle in a formula, wherein the stable flow of the solution C is 50mL/min, a W element-containing soluble salt liquid inlet pipe is not used, and the solution C is subjected to sealing treatment. Controlling the pH value to be 10.9, the ammonia concentration to be 0.3-0.5 mol/L and the temperature to be 65 ℃ in the reaction process, and continuously introducing nitrogen in the reaction process.

2.5, maintaining the reaction time for 65-70 h, stopping feeding until the granularity D50 of the materials in the reaction kettle reaches about 6.0 mu m to obtain mixed slurry E, continuously stirring for 60min, discharging, washing with deionized water at 65 ℃, centrifuging, drying in an air-blast drying oven at 120 ℃ for 15h until the water content reaches the requirement, sieving by using a 400-mesh sieve, and removing iron to obtain the high-nickel cobalt-free precursor.

Comparative example 3

3.1 preparing a solution A with the concentration of an ammonium bicarbonate complexing agent of 9mol/L by using deionized water; deionized water is used for preparing a solution B with the concentration of 2.5mol/L of carbonic acid precipitant.

3.2 preparing a solution C with the total concentration of three ions of Ni, Mn and Al of 1.5mol/L by using deionized water and nickel chloride, manganese chloride and aluminum chloride, wherein the ratio of Ni: mn: al 96: 2: 2.

3.3 Add 80L deionized water into 100L reactor, fill in solution A and B, make into base solution D with pH 11.6, ammonia concentration 0.6mol/L, control base solution temperature 65 deg.C, stir speed 1000 rpm.

3.4 to the reaction kettle with a volume of 0.3m³Introducing nitrogen at a flow rate of/h, introducing the solution A, B, C into the reaction kettle by a precision constant flow pump according to a liquid inlet mode shown in figure 1, wherein the stable flow rate of the solution C is 50mL/min, a liquid inlet pipe of soluble salt containing the W element is not used, and sealing the liquid inlet pipe. Controlling the pH value to be 10.7, the ammonia concentration to be 0.8-1.0 mol/L and the temperature to be 65 ℃ in the reaction process, and continuously introducing nitrogen in the reaction process.

3.5, maintaining the reaction time for 65-70 h, stopping feeding until the granularity D50 of the materials in the reaction kettle reaches about 6.0 mu m to obtain mixed slurry F, continuously stirring for 60min, discharging, washing with deionized water at 55 ℃, centrifuging, drying in a blast drying oven at 120 ℃ for 15h until the water content reaches the requirement, sieving by using a 400-mesh sieve, and removing iron to obtain the high-nickel cobalt-free precursor.

The tungsten-doped high-nickel cobalt-free alloy obtained in examples 1 to 3The precursor and the high-nickel cobalt-free precursor obtained in comparative examples 1-3 are respectively mixed with battery-grade lithium hydroxide according to the lithiation proportion Li (Ni + Mn + R) of 1.05, and subjected to secondary calcination treatment in an oxygen atmosphere, wherein the primary calcination is carried out for 20 hours at 860 ℃, and the secondary calcination is carried out for 15 hours at 740 ℃, so as to obtain the cathode material. The initial charge-discharge performance is tested by using a CR2032 type button cell, and the mass ratio of the anode material in the button cell is as follows: high nickel cobalt-free anode material, acetylene black and polyvinylidene fluoride (PVDF) are 94: 3, a Celgard polypropylene diaphragm is adopted, a metal lithium sheet is used as a cathode, and the electrolyte is 1mol/L LiPF₆+ DEC/EC (1: 1 by volume) mixed solution. The first charge and discharge performance test data of the button cell under the conditions of 25 ℃ and 0.2C are obtained and are shown in Table 1.

The cycle performance of the full-cell is tested by adopting a 053048 soft package cell, the proportion of the anode material, the diaphragm material and the electrolyte in the full-cell is the same as that of the button cell, and the modified natural graphite is used as the cathode, so that a curve chart of the charge-discharge cycle performance of the soft package cell under the conditions of 45 ℃, 3.0-4.2V and 1C is shown in figure 5.

TABLE 1 detection result of semi-electric property of anode material

Examples are Ni: co: mn molar ratio is 96: 2: 2, the conventional high nickel ternary precursor without doped tungsten prepared by the method of example 1 and the mixed lithium source adopt the same sintering process conditions to obtain the cathode material.

The results of the semi-electrical property data in table 1 show that the positive electrode materials of examples 1 to 3 and comparative examples 1 to 3 have no great difference in capacity, but the positive electrode materials obtained in examples 1 to 3 are obviously superior to those of comparative examples 1 to 3 and examples in the first charge-discharge efficiency.

From the results of the full-electric charge-discharge cycle performance data in fig. 5, it can be seen that the capacity retention rate of the positive electrode materials obtained in examples 1 to 3 after multiple charge-discharge cycles is obviously better than that of comparative examples 1 to 3 and the samples.