Modified high-nickel precursor, preparation method thereof and positive electrode material

Abstract

The application provides a modified high-nickel precursor, a preparation method thereof and a positive electrode material, and the preparation method comprises the following steps: under a protective atmosphere, a co-current mixing of a precipitant solution, a modified complexing agent solution and a metal salt solution in a bottom liquid is performed, a co-precipitation reaction is performed to a target particle size, and then washing and drying are performed to obtain the modified high-nickel precursor; the solute in the modified complexing agent solution comprises a complexing agent and a modifier; and the modifier is ammonium lignosulfonate. In the co-precipitation reaction process, the modified complexing agent solution containing the modifier can generate an anionic surfactant, so that the particle dispersibility and the particle sphericity are significantly improved; meanwhile, the lattice constant of the precursor can be expanded, the diffusion dynamics of lithium ions in the corresponding positive electrode material is improved, and therefore the charge-discharge capacity, the rate performance and the cycle stability of the positive electrode material are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium ion batteries, and relates to a high-nickel precursor, in particular to a modified high-nickel precursor and a preparation method thereof and a positive electrode material. BACKGROUND

[0002] Lithium ion batteries with high energy density have a wide range of applications in the storage field of portable electronic devices, electric vehicles and smart grids. As the core component of lithium ion batteries, the performance of the positive electrode material directly affects the energy density, cycle stability and safety performance of the lithium ion battery. In recent years, high-nickel content layered oxide positive electrode materials have become an ideal choice for high-energy-density lithium ion batteries because of their high theoretical capacity and cost-effectiveness.

[0003] However, high-nickel layered oxide positive electrode materials face problems of poor structural stability and electrolyte compatibility during charging and discharging, which often leads to rapid capacity decay and shortens the service life of the battery. Ion doping, surface coating and lattice parameter optimization can solve these technical problems to some extent. Among them, lattice parameter optimization improves the performance of high-nickel layered oxide positive electrode materials by improving the diffusion ability of lithium ions.

[0004] Therefore, it is necessary to provide a modified high-nickel precursor with good dispersibility, high sphericity and good crystallinity, and a preparation method thereof and a positive electrode material. SUMMARY

[0005] The purpose of the present application is to provide a modified high-nickel precursor and a preparation method thereof and a positive electrode material, which can significantly improve the particle dispersibility of the modified high-nickel precursor, improve the particle sphericity, and also expand the lattice constant of the precursor; thereby improving the diffusion dynamics of lithium ions in the corresponding positive electrode material, and improving the charge-discharge capacity, rate performance and cycle stability of the positive electrode material.

[0006] To achieve the purpose of the present application, the following technical solutions are adopted:

[0007] In a first aspect, the present application provides a preparation method of a modified high-nickel precursor, which comprises the following steps:

[0008] Under the condition of a protective atmosphere, the solutions of the precipitating agent, the modified complexing agent and the metal salt are mixed in parallel in the bottom liquid, and a co-precipitation reaction is carried out to the target particle size, and then the modified high-nickel precursor is obtained after washing and drying;

[0009] The solute in the solution of the modified complexing agent includes a complexing agent and a modifier;

[0010] The modifier is ammonium lignosulfonate.

[0011] The present application can produce an anionic surfactant in the process of the coprecipitation reaction by using a modified complexing agent solution containing a modifier, thereby significantly improving the particle dispersibility and the particle sphericity, and also expanding the lattice constant of the precursor and improving the diffusion dynamics of lithium ions in the corresponding positive electrode material, so as to improve the charge-discharge capacity, rate performance and cycle stability of the positive electrode material; in addition, when the ammonium lignosulfonate reacts with the precipitant, ammonia water can be slowly released, the growth rate of the precursor particles is reduced, the pores and defects are reduced, the fluctuation of the ammonia water concentration is inhibited, the crystallinity of the hydroxide precursor is improved, and the quality of the modified high-nickel precursor is improved.

[0012] Preferably, the concentration of the modifier in the modified complexing agent solution is 0.05 mol / L to 0.5 mol / L, preferably 0.15 mol / L to 0.35 mol / L.

[0013] Preferably, the complexing agent in the modified complexing agent solution comprises any one or a combination of at least two of ammonium nitrate, ammonium sulfate, ammonium bisulfate or ammonium chloride.

[0014] Preferably, the concentration of the complexing agent in the modified complexing agent solution is 0.2 mol / L to 2 mol / L, preferably 0.8 mol / L to 1.2 mol / L.

[0015] Preferably, the ammonia concentration in the coprecipitation reaction is 1 g / L to 8 g / L, preferably 3 g / L to 5 g / L.

[0016] Preferably, the temperature in the coprecipitation reaction is 40°C to 70°C.

[0017] Preferably, the coprecipitation reaction comprises a nucleation stage and a growth stage performed in sequence.

[0018] Preferably, the pH value in the nucleation stage is 11.4 to 12.8, preferably 11.8 to 12.3.

[0019] Preferably, the pH value in the growth stage is 9.6 to 10.8, preferably 10.0 to 10.4.

[0020] Preferably, the target particle size refers to a median particle size D50 of 3 μm to 15 μm, preferably 6 μm to 10 μm.

[0021] Preferably, the total concentration of metal ions in the metal salt solution is 1 mol / L to 3 mol / L.

[0022] Preferably, the concentration of the precipitant solution is 20 wt% to 40 wt%.

[0023] Preferably, the pH value of the base solution is 11.5 to 12.8.

[0024] Preferably, the ammonia concentration of the base solution is 0.5 g / L to 4 g / L.

[0025] Preferably, the concentration of the modifier in the base solution is 0.1 mol / L to 0.3 mol / L.

[0026] In a second aspect, the present application provides a modified high-nickel precursor, which is prepared by the preparation method of the first aspect.

[0027] The chemical formula of the modified high-nickel precursor is Ni x Co y Mn 1-x-y (OH)2or Ni x Co y Al 1-x-y (OH)2wherein, 0.6≤x<1, 0≤y≤0.2.

[0028] In a third aspect, the present application provides a positive electrode material, which is prepared from the modified high-nickel precursor of the second aspect.

[0029] Compared with the prior art, the present application has the following beneficial effects:

[0030] By using the modified complexing agent solution containing the modifier, the present application can produce an anionic surfactant in the process of co-precipitation reaction, thereby significantly improving the particle dispersibility and the particle sphericity, and also expanding the lattice constant of the precursor and improving the diffusion dynamics of lithium ions in the corresponding positive electrode material, so as to improve the charge and discharge capacity, the rate performance and the cycle stability of the positive electrode material. Moreover, when the ammonium lignosulfonate reacts with the precipitator, it can slowly release ammonia water, thereby reducing the growth rate of the precursor particles, reducing the pores and defects, and also inhibiting the fluctuation of the ammonia water concentration, which is helpful to improve the crystallinity of the hydroxide precursor and improve the quality of the modified high-nickel precursor. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 SEM (Scanning Electron Microscope) image of the modified high-nickel precursor obtained in Example 1 of the present application;

[0032] Figure 2 SEM image of the high-nickel precursor obtained in Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0033] The technical solutions of the present application will be further described below through specific embodiments. It should be understood by those skilled in the art that the embodiments are only used to help understand the present application, and should not be regarded as specific limitations on the present application.

[0034] The certain embodiment of the present application provides a preparation method of modified high-nickel precursor, which comprises the following steps:

[0035] The co-precipitation reaction is carried out under the condition of a protective atmosphere, and the co-precipitation reaction is carried out by mixing the precipitant solution, the modified complexing agent solution and the metal salt solution in the bottom liquid in parallel, and the modified high-nickel precursor is obtained by washing and drying after the co-precipitation reaction reaches the target particle size;

[0036] The solute in the modified complexing agent solution comprises a complexing agent and a modifier;

[0037] The modifier is ammonium lignosulfonate.

[0038] The present application can significantly improve the particle dispersibility and the particle sphericity by using the modified complexing agent solution containing the modifier to generate an anionic surfactant in the co-precipitation reaction process, and can also expand the lattice constant of the precursor and improve the diffusion dynamics of lithium ions in the corresponding positive electrode material, thereby improving the charge-discharge capacity, rate performance and cycle stability of the positive electrode material. In addition, when ammonium lignosulfonate reacts with the precipitant, ammonia water can be slowly released, the growth rate of the precursor particles is reduced, the pores and defects are reduced, the fluctuation of the ammonia water concentration is inhibited, the crystallinity of the hydroxide precursor is improved, and the quality of the modified high-nickel precursor is improved.

[0039] In some embodiments, the gas used in the protective atmosphere comprises nitrogen and / or argon.

[0040] In some embodiments, the solute composition in the metal salt solution meets the chemical formula requirement of the finally obtained modified high-nickel precursor. In the present application, the chemical formula of the obtained modified high-nickel precursor is Ni x Co y Mn 1-x-y (OH)2or Ni x Co y Al 1-x-y (OH)2, wherein 0.6≤x<1 and 0≤y≤0.2.

[0041] In some embodiments, the solute in the metal salt solution comprises any one or a combination of at least two of a sulfate, a nitrate or a halide, and typical but non-limiting combinations include a combination of a sulfate and a nitrate, a combination of a nitrate and a halide, a combination of a sulfate and a halide, a combination of a sulfate, a nitrate and a halide.

[0042] For example, for Ni ions, the solute provided to modify the Ni in the high nickel precursor includes any one or a combination of at least two of nickel sulfate, nickel nitrate, or nickel chloride, typical but not limited combinations include a combination of nickel sulfate and nickel nitrate, a combination of nickel nitrate and nickel chloride, a combination of nickel sulfate and nickel chloride, or a combination of nickel sulfate, nickel nitrate, and nickel chloride.

[0043] For example, for Co ions, the solute provided to modify the Co in the high nickel precursor includes any one or a combination of at least two of cobalt sulfate, cobalt nitrate, or cobalt chloride, typical but not limited combinations include a combination of cobalt sulfate and cobalt nitrate, a combination of cobalt nitrate and cobalt chloride, a combination of cobalt sulfate and cobalt chloride, or a combination of cobalt sulfate, cobalt nitrate, and cobalt chloride.

[0044] For example, for Mn ions, the solute provided to modify the Mn in the high nickel precursor includes any one or a combination of at least two of manganese sulfate, manganese nitrate, or manganese chloride, typical but not limited combinations include a combination of manganese sulfate and manganese nitrate, a combination of manganese nitrate and manganese chloride, a combination of manganese sulfate and manganese chloride, or a combination of manganese sulfate, manganese nitrate, and manganese chloride.

[0045] For example, for Al ions, the solute provided to modify the Al in the high nickel precursor includes any one or a combination of at least two of aluminum sulfate, aluminum nitrate, or aluminum chloride, typical but not limited combinations include a combination of aluminum sulfate and aluminum nitrate, a combination of aluminum nitrate and aluminum chloride, a combination of aluminum sulfate and aluminum chloride, or a combination of aluminum sulfate, aluminum nitrate, and aluminum chloride.

[0046] In certain embodiments, the concentration of the modifier in the modified complexing agent solution is from 0.05 mol / L to 0.5 mol / L, for example, can be 0.05 mol / L, 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.3 mol / L, 0.35 mol / L, 0.4 mol / L, or 0.5 mol / L, but is not limited to the listed values, and the remaining values in the range are also applicable, preferably from 0.15 mol / L to 0.35 mol / L.

[0047] In certain embodiments, the complexing agent in the modified complexing agent solution includes any one or a combination of at least two of ammonium nitrate, ammonium sulfate, ammonium bisulfate, or ammonium chloride, typical but not limited combinations include a combination of ammonium nitrate and ammonium sulfate, a combination of ammonium sulfate and ammonium bisulfate, a combination of ammonium bisulfate and ammonium chloride, a combination of ammonium nitrate, ammonium sulfate, and ammonium bisulfate, a combination of ammonium sulfate, ammonium bisulfate, and ammonium chloride, or a combination of ammonium nitrate, ammonium sulfate, ammonium bisulfate, and ammonium chloride.

[0048] In some embodiments, the concentration of the complexing agent in the modified complexing agent solution is 0.2 mol / L to 2 mol / L, for example, it can be 0.2 mol / L, 0.5 mol / L, 0.8 mol / L, 1 mol / L, 1.2 mol / L, 1.5 mol / L or 2 mol / L, but is not limited to the listed values, and the remaining values in the value range are also applicable, and preferably, it is 0.8 mol / L to 1.2 mol / L.

[0049] In some embodiments, the concentration of ammonia in the co-precipitation reaction is 1 g / L to 8 g / L, for example, it can be 1 g / L, 3 g / L, 4 g / L, 5 g / L, 6 g / L or 8 g / L, but is not limited to the listed values, and the remaining values in the value range are also applicable, and preferably, it is 3 g / L to 5 g / L.

[0050] In some embodiments, the temperature in the co-precipitation reaction is 40℃ to 70℃, for example, it can be 40℃, 50℃, 60℃ or 70℃, but is not limited to the listed values, and the remaining values in the value range are also applicable.

[0051] In some embodiments, the co-precipitation reaction comprises a nucleation stage and a growth stage performed in sequence.

[0052] In some embodiments, the pH value in the nucleation stage is 11.4 to 12.8, for example, it can be 11.4, 11.5, 11.8, 12, 12.3 or 12.8, but is not limited to the listed values, and the remaining values in the value range are also applicable, and preferably, it is 11.8 to 12.3.

[0053] In some embodiments, the pH value in the growth stage is 9.6 to 10.8, for example, it can be 9.6, 10.0, 10.2, 10.4 or 10.8, but is not limited to the listed values, and the remaining values in the value range are also applicable, and preferably, it is 10.0 to 10.4.

[0054] In some embodiments, the target particle size refers to a median particle size D50 of 3 μm to 15 μm, for example, it can be 3 μm, 6 μm, 8 μm, 10 μm, 12 μm or 15 μm, but is not limited to the listed values, and the remaining values in the value range are also applicable, and preferably, it is 6 μm to 10 μm.

[0055] In some embodiments, the total concentration of metal ions in the metal salt solution is 1 mol / L to 3 mol / L, for example, it can be 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L or 3 mol / L, but is not limited to the listed values, and the remaining values in the value range are also applicable.

[0056] In certain embodiments, the concentration of the precipitant solution is 20 wt% to 40 wt%, such as can be 20 wt%, 25 wt%, 30 wt%, 35 wt%, or 40 wt%, but is not limited to the listed values, and the remaining unlisted values within the range are also applicable.

[0057] In certain embodiments, the precipitant in the precipitant solution comprises any one or a combination of at least two of sodium hydroxide, potassium hydroxide, or lithium hydroxide, typically but not limited to a combination of sodium hydroxide and potassium hydroxide, a combination of potassium hydroxide and lithium hydroxide, a combination of sodium hydroxide and lithium hydroxide, or a combination of sodium hydroxide, potassium hydroxide, and lithium hydroxide.

[0058] The base solution is prepared by adding the precipitant in the precipitant solution, the complexing agent in the modified complexing agent solution, and the modifier in water.

[0059] In certain embodiments, the pH value of the base solution is 11.5 to 12.8, such as can be 11.5, 11.8, 12, 12.5, or 12.8, but is not limited to the listed values, and the remaining unlisted values within the range are also applicable.

[0060] In certain embodiments, the ammonia concentration of the base solution is 0.5 g / L to 4 g / L, such as can be 0.5 g / L, 1 g / L, 2 g / L, 3 g / L, or 4 g / L, but is not limited to the listed values, and the remaining unlisted values within the range are also applicable.

[0061] In certain embodiments, the modifier concentration in the base solution is 0.1 mol / L to 0.3 mol / L, such as can be 0.1 mol / L, 0.2 mol / L, or 0.3 mol / L, but is not limited to the listed values, and the remaining unlisted values within the range are also applicable.

[0062] In certain embodiments, the co-precipitation reaction is accompanied by stirring at a stirring speed of 250 rpm to 350 rpm, such as can be 250 rpm, 280 rpm, 300 rpm, 320 rpm, or 350 rpm, but is not limited to the listed values, and the remaining unlisted values within the range are also applicable.

[0063] An embodiment of the present application provides a modified high-nickel precursor prepared by any of the preparation methods described in the embodiments;

[0064] The chemical formula of the modified high-nickel precursor is Ni x Co y Mn 1-x-y (OH)2or Ni x Co y Al1-x-y (OH)2, wherein 0.6≤x<1, 0≤y≤0.2.

[0065] Some embodiments of the present application provide a positive electrode material prepared from the modified high-nickel precursor of any of the embodiments.

[0066] For example, the modified high-nickel precursor is mixed with a lithium source, and then calcined to obtain the positive electrode material. The lithium source includes, but is not limited to, lithium hydroxide and / or lithium carbonate.

[0067] The chemical formula of the modified high-nickel precursor in the following embodiments and comparative examples is Ni 0.84 Co 0.11 Mn 0.05 (OH)2. The description of the modified high-nickel precursor is only for the purpose of clearly illustrating the technical solutions of the present application, and should not be regarded as a further limitation of the technical solutions of the present application.

[0068] Embodiment 1

[0069] This embodiment provides a preparation method of a modified high-nickel precursor Ni 0.84 Co 0.11 Mn 0.05 (OH)2, which comprises the following steps:

[0070] (1) A bottom solution is prepared using sodium hydroxide, ammonium sulfate, and ammonium lignosulfonate;

[0071] The pH value of the bottom solution is 12, the ammonia concentration is 2 g / L, and the concentration of ammonium lignosulfonate is 0.2 mol / L;

[0072] (2) Under the conditions of nitrogen atmosphere and 300 rpm stirring, the bottom solution is mixed with a precipitant solution (30 wt% sodium hydroxide solution), a modified complexing agent solution, and a metal salt solution in parallel flow, and co-precipitation reaction is carried out to the target particle size (D50 is 8 μm). After alkaline washing, water washing, and drying at 100°C for 12 h, the modified high-nickel precursor is obtained;

[0073] The complexing agent in the modified complexing agent solution is ammonium sulfate, and the modifier is ammonium lignosulfonate; wherein the concentration of the complexing agent in the modified complexing agent solution is 1 mol / L, and the concentration of the modifier is 0.25 mol / L;

[0074] The metal salt in the metal salt solution includes nickel sulfate, cobalt sulfate, and manganese sulfate, and the total concentration of nickel, cobalt, and manganese is 2 mol / L;

[0075] The ammonia concentration in the co-precipitation reaction is 4 g / L, and the temperature is 55°C; the co-precipitation reaction comprises a nucleation stage and a growth stage performed in sequence, the pH value in the nucleation stage is 12, and the pH value in the growth stage is 10.2.

[0076] The SEM image of the modified high-nickel precursor obtained in the example is shown in FIG. 1. Figure 1 As shown in FIG. 1, since the ammonium lignosulfonate is introduced as a modifier in the example, and the ammonium salt is used in combination, the dispersity, sphericity and crystallinity of the modified high-nickel precursor can be significantly improved, and the lattice parameter is expanded, which is helpful to improve the diffusion kinetics of lithium ions in the positive electrode material, thereby improving the electrochemical performance of the positive electrode material.

[0077] Example 2

[0078] The example provides a preparation method of a modified high-nickel precursor Ni 0.84 Co 0.11 Mn 0.05 (OH)2, which comprises the following steps:

[0079] (1) preparing a base solution by using sodium hydroxide, ammonium sulfate and ammonium lignosulfonate;

[0080] The pH value of the base solution is 12, the ammonia concentration is 1 g / L, and the concentration of ammonium lignosulfonate is 0.2 mol / L;

[0081] (2) under the condition of nitrogen atmosphere and 300 rpm stirring, mixing the precipitant solution (25 wt% sodium hydroxide solution), the modified complexing agent solution and the metal salt solution in the base solution in parallel, performing co-precipitation reaction to the target particle size (D50 is 8 μm), performing alkali washing, water washing and 100°C drying for 12 h to obtain the modified high-nickel precursor;

[0082] The complexing agent in the modified complexing agent solution is ammonium sulfate, and the modifier is ammonium lignosulfonate; wherein the concentration of the complexing agent in the modified complexing agent solution is 0.8 mol / L, and the concentration of the modifier is 0.15 mol / L;

[0083] The metal salt in the metal salt solution comprises nickel sulfate, cobalt sulfate and manganese sulfate, and the total concentration of nickel, cobalt and manganese is 2 mol / L;

[0084] The ammonia concentration in the co-precipitation reaction is 3 g / L, and the temperature is 50°C; the co-precipitation reaction comprises a nucleation stage and a growth stage performed in sequence, the pH value in the nucleation stage is 11.8, and the pH value in the growth stage is 10.0.

[0085] Example 3

[0086] The example provides a preparation method of a modified high-nickel precursor Ni 0.84 Co0.11 Mn 0.05 A preparation method of the modified high-nickel precursor Ni

[0087] (1) preparing a base solution using sodium hydroxide, ammonium sulfate and ammonium lignosulfonate;

[0088] The pH value of the base solution is 12, the ammonia concentration is 3 g / L, and the ammonium lignosulfonate concentration is 0.2 mol / L;

[0089] (2) under the conditions of nitrogen atmosphere and 300 rpm stirring, mixing the precipitant solution (35 wt% sodium hydroxide solution), the modified complexing agent solution and the metal salt solution in the base solution in parallel flow, carrying out a co-precipitation reaction to a target particle size (D50 of 8 μm), and then performing alkali washing, water washing and 100°C drying for 12 h to obtain the modified high-nickel precursor;

[0090] The complexing agent in the modified complexing agent solution is ammonium sulfate, and the modifier is ammonium lignosulfonate; wherein the complexing agent concentration in the modified complexing agent solution is 1.2 mol / L, and the modifier concentration is 0.35 mol / L;

[0091] The metal salt in the metal salt solution includes nickel sulfate, cobalt sulfate and manganese sulfate, and the total concentration of nickel, cobalt and manganese is 2 mol / L;

[0092] The ammonia concentration during the co-precipitation reaction is 5 g / L, and the temperature is 60°C; the co-precipitation reaction includes a nucleation stage and a growth stage performed in sequence, the pH value of the nucleation stage is 12.3, and the pH value of the growth stage is 10.4.

[0093] Example 4

[0094] The present embodiment provides a modified high-nickel precursor Ni 0.84 Co 0.11 Mn 0.05 A preparation method of the modified high-nickel precursor Ni

[0095] (1) preparing a base solution using sodium hydroxide, ammonium sulfate and ammonium lignosulfonate;

[0096] The pH value of the base solution is 11.5, the ammonia concentration is 0.5 g / L, and the ammonium lignosulfonate concentration is 0.1 mol / L;

[0097] (2) under the conditions of nitrogen atmosphere and 300 rpm stirring, mixing the precipitant solution (35 wt% sodium hydroxide solution), the modified complexing agent solution and the metal salt solution in the base solution in parallel flow, carrying out a co-precipitation reaction to a target particle size (D50 of 8 μm), and then performing alkali washing, water washing and 100°C drying for 12 h to obtain the modified high-nickel precursor;

[0098] The complexing agent in the modified complexing agent solution is ammonium sulfate, and the modifier is ammonium lignosulfonate; wherein the concentration of the complexing agent in the modified complexing agent solution is 0.2 mol / L, and the concentration of the modifier is 0.05 mol / L;

[0099] The metal salt in the metal salt solution includes nickel sulfate, cobalt sulfate and manganese sulfate, and the total concentration of nickel, cobalt and manganese is 1 mol / L;

[0100] The ammonia concentration in the co-precipitation reaction is 1 g / L, and the temperature is 40℃; the co-precipitation reaction includes a nucleation stage and a growth stage performed in sequence, the pH value of the nucleation stage is 11.4, and the pH value of the growth stage is 9.6.

[0101] Example 5

[0102] The present embodiment provides a preparation method of a modified high-nickel precursor Ni 0.84 Co 0.11 Mn 0.05 (OH)2, the preparation method includes the following steps:

[0103] (1) using sodium hydroxide, ammonium sulfate and ammonium lignosulfonate to prepare a base solution;

[0104] The pH value of the base solution is 12.8, the ammonia concentration is 4 g / L, and the concentration of ammonium lignosulfonate is 0.3 mol / L;

[0105] (2) under the condition of nitrogen atmosphere and 300 rpm stirring, the base solution is mixed with a precipitant solution (40wt% sodium hydroxide solution), a modified complexing agent solution and a metal salt solution in parallel, and the co-precipitation reaction is carried out to the target particle size (D50 is 8 μm), and then the modified high-nickel precursor is obtained by alkali washing, water washing and 100℃ drying for 12h;

[0106] The complexing agent in the modified complexing agent solution is ammonium sulfate, and the modifier is ammonium lignosulfonate; wherein the concentration of the complexing agent in the modified complexing agent solution is 2 mol / L, and the concentration of the modifier is 0.5 mol / L;

[0107] The metal salt in the metal salt solution includes nickel sulfate, cobalt sulfate and manganese sulfate, and the total concentration of nickel, cobalt and manganese is 3 mol / L;

[0108] The ammonia concentration in the co-precipitation reaction is 8 g / L, and the temperature is 70℃; the co-precipitation reaction includes a nucleation stage and a growth stage performed in sequence, the pH value of the nucleation stage is 12.8, and the pH value of the growth stage is 10.8.

[0109] Example 6

[0110] The present embodiment provides a preparation method of a modified high-nickel precursor Ni 0.84 Co0.11 Mn 0.05 The preparation method of the modified high-nickel precursor Ni

[0111] Example 7

[0112] The present example provides a modified high-nickel precursor Ni 0.84 Co 0.11 Mn 0.05 The preparation method of the modified high-nickel precursor Ni

[0113] Example 8

[0114] The present example provides a modified high-nickel precursor Ni 0.84 Co 0.11 Mn 0.05 The preparation method of the modified high-nickel precursor Ni

[0115] Example 9

[0116] The present example provides a modified high-nickel precursor Ni 0.84 Co 0.11 Mn 0.05 The preparation method of the modified high-nickel precursor Ni

[0117] Comparative Example 1

[0118] The present example provides a high-nickel precursor Ni 0.84 Co 0.11 Mn 0.05 The preparation method of the high-nickel precursor Ni

[0119] (1) preparing a base solution by using sodium hydroxide and ammonium sulfate;

[0120] The pH value of the base solution is 12, and the ammonia concentration is 2 g / L;

[0121] (2) under the conditions of nitrogen atmosphere and 300 rpm stirring, mixing the base solution, a complexing agent solution and a metal salt solution in parallel flow in the base solution, and carrying out a co-precipitation reaction to a target particle size (D50 is 8 μm), and then carrying out alkali washing, water washing and 100°C drying for 12 h to obtain the high-nickel precursor;

[0122] The complexing agent in the complexing agent solution is ammonium sulfate, and the complexing agent concentration is 1 mol / L;

[0123] The metal salts in the metal salt solution include nickel sulfate, cobalt sulfate and manganese sulfate, and the total concentration of nickel, cobalt and manganese is 2 mol / L.

[0124] The ammonia concentration during the coprecipitation reaction is 4 g / L, and the temperature is 55 °C. The coprecipitation reaction includes a nucleation stage and a growth stage, which proceed sequentially. The pH value of the nucleation stage is 12, and the pH value of the growth stage is 10.2.

[0125] The SEM image of the high-nickel precursor obtained in this comparative example is shown below. Figure 2 As shown, by Figure 1 and Figure 2 The comparison shows that ammonium lignosulfonate, as a modifier and in combination with ammonium salts, can significantly improve the dispersibility, sphericity and crystallinity of modified high-nickel precursors, and expand the lattice parameters, which helps to improve the diffusion kinetics of lithium ions in cathode materials, thereby improving the electrochemical performance of cathode materials.

[0126] Comparative Example 2

[0127] This comparative example provides a high-nickel precursor Ni 0.84 Co 0.11 Mn 0.05 A method for preparing (OH)2, the method comprising the following steps:

[0128] (1) Prepare the base solution using sodium hydroxide and ammonium sulfate;

[0129] The pH of the base solution was 12, and the ammonia concentration was 2 g / L;

[0130] (2) Under nitrogen atmosphere and stirring at 300 rpm, the precipitant solution (30 wt% sodium hydroxide solution), the modified complexing agent solution and the metal salt solution are mixed in parallel in the bottom liquid and co-precipitated to the target particle size (D50 is 8 μm). After alkali washing, water washing and drying at 100 °C for 12 h, the high nickel precursor is obtained.

[0131] The complexing agent in the modified complexing agent solution is ammonium sulfate, and the modifier is ammonium lignosulfonate; wherein the concentration of the complexing agent in the modified complexing agent solution is 1 mol / L, and the concentration of the modifier is 0.25 mol / L;

[0132] The metal salts in the metal salt solution include nickel sulfate, cobalt sulfate and manganese sulfate, and the total concentration of nickel, cobalt and manganese is 2 mol / L.

[0133] The ammonia concentration during the coprecipitation reaction is 4 g / L, and the temperature is 55 °C. The coprecipitation reaction includes a nucleation stage and a growth stage, which proceed sequentially. The pH value of the nucleation stage is 12, and the pH value of the growth stage is 10.2.

[0134] Comparative Example 3

[0135] The present comparative example provides a high-nickel precursor Ni 0.84 Co 0.11 Mn 0.05 The preparation method of the high-nickel precursor Ni

[0136] (1) a base solution was prepared using sodium hydroxide, ammonium sulfate and ammonium lignosulfonate;

[0137] The pH value of the base solution was 12, the ammonia concentration was 2 g / L, and the concentration of ammonium lignosulfonate was 0.2 mol / L;

[0138] (2) under the conditions of nitrogen atmosphere and stirring at 300 rpm, a precipitant solution (30 wt% sodium hydroxide solution), a complexing agent solution and a metal salt solution were mixed in parallel in the base solution, and a co-precipitation reaction was performed to a target particle size (D50 of 8 μm), followed by alkaline washing, water washing and drying at 100°C for 12 h to obtain the high-nickel precursor;

[0139] The complexing agent in the complexing agent solution was ammonium sulfate, and the concentration was 1 mol / L;

[0140] The metal salt in the metal salt solution included nickel sulfate, cobalt sulfate and manganese sulfate, and the total concentration of nickel, cobalt and manganese was 2 mol / L;

[0141] The ammonia concentration during the co-precipitation reaction was 4 g / L, and the temperature was 55°C; the co-precipitation reaction included a nucleation stage and a growth stage performed in sequence, the pH value of the nucleation stage was 12, and the pH value of the growth stage was 10.2.

[0142] Comparative Example 4

[0143] The present comparative example provides a high-nickel precursor Ni 0.84 Co 0.11 Mn 0.05 The preparation method of the high-nickel precursor Ni

[0144] (1) a base solution was prepared using sodium hydroxide and ammonia water;

[0145] The pH value of the base solution was 12, and the ammonia concentration was 2 g / L;

[0146] (2) under the conditions of nitrogen atmosphere and stirring at 300 rpm, a precipitant solution (30 wt% sodium hydroxide solution), a complexing agent solution and a metal salt solution were mixed in parallel in the base solution, and a co-precipitation reaction was performed to a target particle size (D50 of 8 μm), followed by alkaline washing, water washing and drying at 100°C for 12 h to obtain the high-nickel precursor;

[0147] The complexing agent in the complexing agent solution was ammonia water, and the concentration was 1 mol / L;

[0148] The metal salt in the metal salt solution comprises nickel sulfate, cobalt sulfate and manganese sulfate, and the total concentration of nickel, cobalt and manganese is 2 mol / L.

[0149] The ammonia concentration in the co-precipitation reaction is 4 g / L, and the temperature is 55°C; the co-precipitation reaction comprises a nucleation stage and a growth stage performed in sequence, the pH value in the nucleation stage is 12, and the pH value in the growth stage is 10.2.

[0150] Comparative Example 5

[0151] This comparative example provides a preparation method of a high-nickel precursor Ni 0.84 Co 0.11 Mn 0.05 (OH)2, which comprises the following steps:

[0152] (1) using sodium hydroxide to prepare a base solution;

[0153] The pH value of the base solution is 12;

[0154] (2) under the condition of nitrogen atmosphere and 300 rpm stirring, mixing the precipitant solution (30 wt% sodium hydroxide solution), the complexing agent solution and the metal salt solution in the base solution in parallel, co-precipitation reaction to the target particle size (D50 is 8 μm), and then alkaline washing, water washing and 100°C drying for 12 h to obtain the high-nickel precursor;

[0155] The complexing agent in the complexing agent solution is ammonia water, and the concentration is 1 mol / L;

[0156] The metal salt in the metal salt solution comprises nickel sulfate, cobalt sulfate and manganese sulfate, and the total concentration of nickel, cobalt and manganese is 2 mol / L.

[0157] The ammonia concentration in the co-precipitation reaction is 4 g / L, and the temperature is 55°C; the co-precipitation reaction comprises a nucleation stage and a growth stage performed in sequence, the pH value in the nucleation stage is 12, and the pH value in the growth stage is 10.2.

[0158] Performance characterization

[0159] The sphericity, specific surface area, tap density and lattice constant of the precursor obtained in the above examples and comparative examples are determined, and the results are shown in Table 1.

[0160] Among them, the sphericity is determined by image analysis method, and the value is the ratio of equivalent diameter to maximum diameter; the lattice constant c / a ratio is calculated after refining the XRD pattern.

[0161] Table 1

[0162]

[0163] As can be seen from Table 1, the preparation method provided by the application can improve the tap density and lattice constant (c / a ratio) of the obtained modified high-nickel precursor, and the sphericity is relatively high; specifically, the sphericity can be greater than 0.896, the tap density can be greater than 1.614 g / cm 3 Above, while the lattice constant is greater than 1.486; as a preferred technical solution of the application, the sphericity can be greater than 0.948, the tap density can be greater than 1.832 g / cm 3 Above, while the lattice constant is greater than 1.551.

[0164] As can be seen from the comparison between Comparative Example 1 and Example 1, when no modifier is added to the base solution and the complexing agent, the sphericity of the obtained precursor is obviously reduced, not only is the specific surface area reduced from 12.25 m 2 / g to 10.85 m 2 / g, but also the tap density is reduced from 1.907 g / cm 3 / g to 1.723 g / cm 3 / g, but also the tap density is reduced from 1.907 g / cm 3 / g to 1.723 g / cm 3 / g, but also the tap density is reduced from 1.907 g / cm 3 / g to 1.723 g / cm 3 / G, and the lattice constant is reduced from 1.578 to 1.463; as can be seen from the comparison between Comparative Example 2, Comparative Example 3 and Example 1, when no modifier is added to the base solution or the complexing agent, the specific surface area, the tap density, the sphericity and the lattice constant are also obviously reduced, which also shows that the use of the modifier in the application can improve the dispersibility and the sphericity of the precursor, and also can expand the lattice constant of the precursor.

[0165] As can be seen from the comparison between Comparative Example 4 and Example 1, the use of ammonia as the complexing agent will cause large fluctuations in the ammonia concentration during the preparation process, thereby causing the sphericity, the dispersibility and the tap density to decrease, and the lattice constant to obviously decrease relative to the use of the modifier. In Comparative Example 5, no ammonia is added to the base solution based on Comparative Example 4, which causes the free ammonia in the nucleation stage to decrease, the particle size to be out of control, and the sphericity, the tap density and the lattice constant to further decrease.

[0166] The precursors obtained in the above examples and comparative examples are used to prepare positive electrode materials, and the electrochemical performance is tested:

[0167] Li2CO3 and the precursor are uniformly mixed by a high-speed mixer, and sintering is performed in an air atmosphere, the sintering temperature is 800°C, and the time is 12h, to obtain a positive electrode material; the theoretical molar ratio of lithium in Li2CO3 to the precursor is 1.03:1, and the loss on ignition is supplemented according to the loss on sintering.

[0168] The positive electrode material, the binder polyvinylidene fluoride and the conductive agent Super P are added into N-methylpyrrolidone in a mass ratio of 97:1.5:1.5 to form a first positive electrode slurry, which is then uniformly coated on a positive electrode current collector aluminum foil, dried and rolled to obtain a positive electrode sheet;

[0169] The graphite, the conductive agent acetylene black, the thickening agent CMC and the binder SBR are mixed in a mass ratio of 96:1:1.5:1.5, and a solvent deionized water is added to fully stir to obtain a negative electrode slurry, which is uniformly coated on a negative electrode current collector copper foil, dried, cold-pressed and cut to obtain a negative electrode sheet;

[0170] The ethylene carbonate EC, the methyl ethyl carbonate EMC and the diethyl carbonate DEC are mixed in a volume ratio of 1:1:1, and then the fully dried lithium salt LiPF6 is dissolved in the mixed solvent to prepare an electrolyte with a concentration of 1 mol / L;

[0171] The positive electrode sheet, the separator and the negative electrode sheet are sequentially laminated, and then wrapped with an aluminum plastic film, dried, injected with the electrolyte, and subjected to packaging, standing and formation processes to obtain a lithium ion battery. The separator is a PE porous film with a thickness of 11 μm, a gas permeability of 280 s / 100 mL and a porosity of 40%.

[0172] The initial specific capacity, cycle capacity retention rate and rate performance of the obtained lithium ion battery are tested, wherein the electrochemical performance test is carried out at room temperature in the voltage range of 2.8-4.3 V, and after 3 cycles at a rate of 0.1 C, the battery is cycled at a rate of 1 C for 100 cycles. The results are shown in Table 2.

[0173] Table 2

[0174]

[0175] As can be seen from Table 2, the preparation method provided by the present application can improve the initial discharge specific capacity of the obtained positive electrode material to be above 193.2 mAh / g, and the 100-cycle capacity retention rate to be above 92.1%. As a preferred technical solution of the present application, the initial discharge specific capacity can be above 194.9 mAh / g, and the 100-cycle capacity retention rate can be above 93.3%. This shows that the preparation method provided by the present application improves the diffusion dynamics of lithium ions in the positive electrode material by using a modifier, thereby improving the charge and discharge capacity and the cycle stability of the positive electrode material.

[0176] A comparison of Comparative Example 1 and Example 1 shows that when no modifier is added to the substrate or complexing agent, the initial discharge specific capacity of the cathode material corresponding to the precursor decreases from 196.8 mAh / g to 187.9 mAh / g, and the cycle stability decreases significantly. A comparison of Comparative Examples 2 and 3 with Example 1 shows that when no modifier is added to the substrate or complexing agent, the initial discharge specific capacity and cycle stability also decrease significantly.

[0177] A comparison of Comparative Example 4 and Example 1 shows that the precursor obtained using ammonia as a complexing agent exhibits significantly reduced sphericity, dispersibility, tap density, and lattice constant compared to Example 1, resulting in a significant decrease in the electrochemical performance of the corresponding cathode material. Comparative Example 5, based on Comparative Example 4, did not add ammonia to the substrate, and the electrochemical performance of the cathode material corresponding to the obtained precursor also showed a significant decrease. This demonstrates that the present invention, through the use of a modifier, improves the dispersibility, sphericity, and lattice constant of the precursor, thereby improving the diffusion kinetics of lithium ions in the cathode material, and thus enhancing the charge-discharge capacity and cycle stability of the cathode material.

[0178] In summary, this invention utilizes a modified complexing agent solution containing a modifier to generate anionic surfactants during the co-precipitation reaction, thereby significantly improving particle dispersibility and sphericity. It also extends the precursor lattice constant, improving the diffusion kinetics of lithium ions in the corresponding cathode material, thus enhancing the charge / discharge capacity, rate performance, and cycle stability of the cathode material. Furthermore, the reaction of ammonium lignosulfonate with the precipitant slowly releases ammonia, reducing the growth rate of precursor particles, thereby decreasing porosity and defects. It also suppresses fluctuations in ammonia concentration, contributing to improved crystallinity of the hydroxide precursor and enhancing the quality of the modified high-nickel precursor.

[0179] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a modified high-nickel precursor, characterized by, The preparation method comprises the following steps: Under a protective atmosphere, a precipitant solution, a modified complexing agent solution and a metal salt solution are mixed in a bottom liquid in parallel, and a co-precipitation reaction is performed to a target particle size, and then the modified high-nickel precursor is obtained through washing and drying; The solute in the modified complexing agent solution comprises a complexing agent and a modifier; The modifier is ammonium lignosulfonate; The precipitant in the precipitant solution comprises any one or a combination of at least two of sodium hydroxide, potassium hydroxide or lithium hydroxide; The complexing agent in the modified complexing agent solution comprises any one or a combination of at least two of ammonium nitrate, ammonium sulfate, ammonium bisulfate or ammonium chloride; The bottom liquid is prepared by adding the precipitant in the precipitant solution, the complexing agent in the modified complexing agent solution and the modifier in water.

2. The production method according to claim 1, characterized by, The concentration of the modifier in the modified complexing agent solution is 0.05 mol / L to 0.5 mol / L.

3. The preparation method according to claim 2, characterized in that, The concentration of the modifier in the modified complexing agent solution is 0.15 mol / L to 0.35 mol / L.

4. The method of claim 1, wherein, The concentration of the complexing agent in the modified complexing agent solution is 0.2 mol / L to 2 mol / L.

5. The preparation method according to claim 4, characterized in that, The concentration of the complexing agent in the modified complexing agent solution is 0.8 mol / L to 1.2 mol / L.

6. The method of claim 1, wherein, The ammonia concentration during the co-precipitation reaction is 1 g / L to 8 g / L.

7. The preparation method according to claim 6, characterized in that, The ammonia concentration during the co-precipitation reaction is 3 g / L to 5 g / L.

8. The method of claim 1, wherein, The temperature during the co-precipitation reaction is 40℃ to 70℃.

9. The method of claim 1, wherein, The co-precipitation reaction comprises a nucleation stage and a growth stage performed in sequence.

10. The method of claim 9, wherein, The pH value of the nucleation stage is 11.4 to 12.

8.

11. The method of claim 10, wherein, The pH value of the nucleation stage is 11.8 to 12.

3.

12. The method of claim 9, wherein, The pH value of the growth stage is 9.6 to 10.

8.

13. The method of claim 12, wherein, The pH value of the growth stage is 10.0 to 10.

4.

14. The method of claim 1, wherein, The target particle size refers to a median particle size D50 of 3 μm to 15 μm.

15. The method of claim 14, wherein, The target particle size refers to a median particle size D50 of 6 μm to 10 μm.

16. The method of claim 1, wherein, The total concentration of metal ions in the metal salt solution is 1 mol / L to 3 mol / L.

17. The method of claim 1, wherein, The concentration of the precipitant solution is 20 wt% to 40 wt%.

18. The method of claim 1, wherein, The pH value of the bottom liquid is 11.5 to 12.

8.

19. The method of claim 1, wherein, The ammonia concentration of the bottom liquid is 0.5 g / L to 4 g / L.

20. The method of claim 1, wherein, The concentration of the modifier in the bottom liquid is 0.1 mol / L to 0.3 mol / L.

21. A modified high nickel precursor, characterized in that, The modified high-nickel precursor is prepared by the preparation method in any one of claims 1 to 20; The modified high-nickel precursor has a chemical formula of Ni x Co y Mn 1-x-y (OH)2or Ni x Co y Al 1-x-y (OH)2, wherein 0.6≤x<1, 0≤y≤0.

2.

22. A positive electrode material, characterized by comprising: The positive electrode material is prepared from the modified high-nickel precursor in claim 21.

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