Ternary precursor and preparation method thereof, positive electrode material and battery

Abstract

The invention provides a ternary precursor and a preparation method thereof, a positive electrode material and a battery, and the preparation method comprises the following steps: introducing a nickel-cobalt-manganese metal source solution into a first precipitator solution, and carrying out a nucleation reaction to obtain crystal nucleus slurry; a complexing agent solution is supplemented into the crystal nucleus slurry, then a nickel-cobalt-manganese metal source solution, a second precipitant solution and the complexing agent solution are introduced in a parallel flow mode, and a growth reaction is carried out; and when the solid content of the system is more than 700g / L in the growth reaction, performing a morphology-guided reaction to obtain the ternary precursor. According to the preparation method disclosed by the invention, the crystal nucleus is prepared through an inverse addition method, then the crystal nucleus grows towards a thick hexagonal sheet, and finally, morphology guidance is performed under high solid content, so that the ternary precursor with high tap density, small length-width ratio and multiple active crystal faces is formed, and the electrochemical performance of the positive electrode material is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of batteries, and relates to a ternary precursor, a preparation method thereof, a positive electrode material and a battery. BACKGROUND

[0002] Lithium ion batteries are widely used in new energy electric vehicles, digital products, mobile phones and other fields due to high working voltage, high energy density and long cycle life. However, with the rapid development of electric vehicles and other industries, the requirements for the energy density and cycle life of lithium ion batteries are becoming higher and higher. The ternary positive electrode material is widely concerned due to its high capacity and high corresponding battery energy density.

[0003] The ternary precursor is a key raw material for preparing the ternary positive electrode material. Due to the inheritance of the precursor by the positive electrode material, the particle size distribution, micro morphology and crystal structure of the precursor directly determine the particle size distribution, micro morphology and crystal structure of the battery positive electrode material. Among them, the crystal face orientation and aspect ratio of the primary particles of the ternary precursor have a great influence on the morphology of the sintered positive electrode material, and further affect the compaction density and cycle performance of the material. Therefore, it is of great significance to regulate the crystal face growth of the primary particles of the ternary precursor. Although the ordinary crystal face regulation method can obtain ternary precursors with different active crystal face ratios by controlling the reaction parameters and using additives, the primary particles of the ternary precursors are basically hexagonal plates, and the aspect ratio is basically > 2, which leads to insufficient improvement of the sphericity and compaction density of the positive electrode material, and limited improvement of the electrical performance.

[0004] Based on the above research, it is necessary to provide a preparation method of a ternary precursor, which can further regulate the morphology of the primary particles of the ternary precursor and improve the sphericity, compaction density and electrochemical performance of the positive electrode material. SUMMARY

[0005] The purpose of the present application is to provide a ternary precursor, a preparation method thereof, a positive electrode material and a battery. The preparation method prepares crystal nuclei by reverse addition method, then makes the crystal nuclei grow into thick hexagonal plates, and finally performs morphology guidance under high solid content, thereby forming a ternary precursor with high tap density, small aspect ratio and many active crystal faces, so as to improve the electrochemical performance 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 ternary precursor, which comprises the following steps:

[0008] (1) introducing a nickel-cobalt-manganese metal source solution into a first precipitant solution to perform a nucleation reaction, so as to obtain a crystal nucleus slurry;

[0009] (2) first supplementing the complexing agent solution in the crystal nucleus slurry of step (1), and then co-currently feeding the nickel-cobalt-manganese metal source solution, the second precipitant solution and the complexing agent solution to carry out the growth reaction;

[0010] (3) when the solid content of the system in the growth reaction of step (2) is above 700 g / L (for example, it can be 700 g / L, 800 g / L, 900 g / L or 1000 g / L), a morphology guiding reaction is carried out to obtain the ternary precursor.

[0011] Firstly, the nickel-cobalt-manganese metal source solution is fed into the first precipitant solution in the present application, on the one hand, compared with feeding the first precipitant solution into the nickel-cobalt-manganese metal source solution, the pH of the system is high, the particle size of the crystal nucleus is small under high pH, and the experimental stability is higher, on the other hand, during the reverse feeding process, the pH gradually decreases from high to low, the orientation of the primary particles will gradually change, and the crystal face of the layered hydroxide gradually grows from the {001} face to the {101} face, which is beneficial to the formation of granular primary particles instead of amorphous lamellar, so that the granular amorphous crystal nucleus with good dispersity can be obtained; then the complexing agent solution is first supplemented, and then the materials are co-currently fed into the growth stage, so that the granular amorphous crystal nucleus grows into a thick hexagonal sheet, and when the solid content of the system in the growth reaction is above 700 g / L, a morphology guiding reaction is carried out, the gap between the primary particles will be gradually filled, the morphology will change to a polyhedron, and the aspect ratio can be reduced to below 2, while if the solid content is less than 700 g / L, the primary particles are only slightly thick hexagonal sheets, and the aspect ratio is still greater than 2, therefore, through the cooperation of each stage, the primary particles of the ternary precursor can be polyhedral structure, and part of the primary particles are similar to octahedral structure, at the same time, the prepared ternary precursor has high tap density, small aspect ratio and many active crystal faces, which is beneficial to improving the electrochemical performance of the positive electrode material.

[0012] As mentioned above, the ternary precursor of the present application will grow preferentially to the {101} face, so that more {101} faces, that is, side faces, can be exposed, the size difference between the thickness direction and the diameter direction of the primary particles is small, the sintering shrinkage is more uniform, and the binding force between the primary particles is stronger, so that local collapse is less likely to occur, and finally the positive electrode material with smoother surface, more round shape and larger tap density is obtained; in addition, the {101} face is the main channel for lithium ion deintercalation, and the higher the proportion is, the more conducive to improving the lithium ion deintercalation capacity, so as to further improve the electrochemical performance of the positive electrode material.

[0013] It should be noted that the preparation method of the present application is carried out in a reaction kettle under stirring, and protective gas (such as nitrogen) is continuously fed into the kettle to prevent oxidation.

[0014] Preferably, the pH of the first precipitant solution in step (1) is 12-13, for example, it can be 12, 12.2, 12.4, 12.6, 12.8 or 13, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0015] Preferably, the first precipitant solution in step (1) and the second precipitant solution in step (2) each independently comprises a sodium hydroxide solution and / or a potassium hydroxide solution.

[0016] Preferably, the first precipitant solution is prepared by mixing a second precipitant solution and pure water.

[0017] Preferably, the complexing agent solution in step (2) comprises ammonia water.

[0018] Preferably, the temperature of the nucleation reaction in step (1) is 40-60°C, for example, it can be 40°C, 45°C, 50°C, 55°C or 60°C, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0019] Preferably, the time for passing the nickel-cobalt-manganese metal source solution into the first precipitant solution in step (1) is 0.5-3h, for example, it can be 0.5h, 1h, 1.5h, 2h, 2.5h or 3h, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0020] Preferably, after the nucleation reaction in step (1) is completed, the pH of the system is reduced to 10-11, for example, it can be 10, 10.2, 10.4, 10.6, 10.8 or 11, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0021] Preferably, in the nickel-cobalt-manganese metal source solution in step (1) and step (2), the molar ratio of nickel ions, cobalt ions and manganese ions is x:y:(1-x-y), wherein 1-x-y≥0, 0.5≤x≤0.8, for example, it can be 0.5, 0.6, 0.7 or 0.8, 0.05≤y≤0.3, for example, it can be 0.05, 0.1, 0.12, 0.14, 0.16, 0.18, 0.2, 0.25 or 0.3, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0022] Preferably, the total metal ion concentration of the nickel-cobalt-manganese metal source solution in step (1) and step (2) is 0.5-2mol / L, for example, it can be 0.5mol / L, 1mol / L, 1.5mol / L or 2mol / L, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0023] Preferably, the nickel-cobalt-manganese metal source solution in step (1) and step (2) can be a sulfate solution, a nitrate solution or a chloride solution of nickel-cobalt-manganese metal.

[0024] Preferably, a first crystal face directing agent is added in the growth reaction in step (2).

[0025] Preferably, the concentration of the first crystal face directing agent in the growth reaction system in step (2) is 0 g / L to 1 g / L, for example, 0 g / L, 0.2 g / L, 0.4 g / L, 0.6 g / L, 0.8 g / L or 1 g / L, but not limited to the listed values, and other values not listed in the value range are also applicable.

[0026] In the growth stage, the first crystal face directing agent can be added to inhibit the growth of the {001} face and promote the exposure of the {101} face. The {101} face is the side face of the precursor primary particles. The thicker the side face, the larger the corresponding width, and the smaller the corresponding aspect ratio. However, the amount of the first crystal face directing agent should not be too much, otherwise the cost will be increased and the improvement effect will not be obvious.

[0027] Preferably, the first crystal face directing agent includes any one or a combination of at least two of octadecyl phosphonic acid, dodecyl phosphonic acid, vinyl phosphonic acid, sodium dodecyl benzene sulfonate, cetyl trimethyl ammonium bromide, polyethylene glycol or polyvinyl pyrrolidone.

[0028] Preferably, the concentration of the complexing agent in the solution added to the system in step (2) is 2 g / L to 6 g / L, for example, 2 g / L, 3 g / L, 4 g / L, 5 g / L or 6 g / L, but not limited to the listed values, and other values not listed in the value range are also applicable.

[0029] Preferably, the temperature of the growth reaction in step (2) is 50℃ to 80℃, for example, 50℃, 60℃, 70℃ or 80℃, and the pH is 10 to 11, for example, 10, 10.2, 10.4, 10.6, 10.8 or 11, but not limited to the listed values, and other values not listed in the value range are also applicable.

[0030] Preferably, the time of the growth reaction in step (2) is 30h to 50h, for example, 30h, 35h, 40h, 45h or 50h, but not limited to the listed values, and other values not listed in the value range are also applicable.

[0031] Preferably, the concentration of the complexing agent in the system of the growth reaction of step (2) is 2 g / L to 6 g / L, for example, it can be 2 g / L, 3 g / L, 4 g / L, 5 g / L or 6 g / L, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0032] Preferably, the concentration of the complexing agent in the system of the growth reaction of step (2) is 2 g / L to 6 g / L, for example, it can be 2 g / L, 3 g / L, 4 g / L, 5 g / L or 6 g / L, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0033] Preferably, the concentration of the complexing agent in the system of the growth reaction of step (2) is 2 g / L to 6 g / L, for example, it can be 2 g / L, 3 g / L, 4 g / L, 5 g / L or 6 g / L, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0034] Preferably, the concentration of the complexing agent in the system of the growth reaction of step (2) is 2 g / L to 6 g / L, for example, it can be 2 g / L, 3 g / L, 4 g / L, 5 g / L or 6 g / L, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0035] Preferably, the concentration of the complexing agent in the system of the growth reaction of step (2) is 2 g / L to 6 g / L, for example, it can be 2 g / L, 3 g / L, 4 g / L, 5 g / L or 6 g / L, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0036] It should be noted that during the morphology guiding reaction of step (3), the reaction parameters of the growth stage of step (2) are maintained, and the co-current feeding and concentration are continued, that is, the temperature, pH and concentration of the complexing agent in the system of the morphology guiding reaction of step (3) are the same as those of the growth reaction of step (2).

[0037] Preferably, the time of the morphology guiding reaction of step (3) is 40 h to 80 h, for example, it can be 40 h, 50 h, 60 h, 70 h or 80 h, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0038] Preferably, a second crystal face directing agent is also added during the morphology guiding reaction of step (3).

[0039] Preferably, the concentration of the second crystal face directing agent in the system of the morphology guiding reaction of step (3) is 0 g / L to 1 g / L, for example, it can be 0 g / L, 0.2 g / L, 0.4 g / L, 0.6 g / L, 0.8 g / L or 1 g / L, but is not limited to the listed values, and other values not listed in the value range are also applicable, preferably 0.05 g / L to 0.2 g / L.

[0040] The second crystal face directing agent can be added in the morphology guiding stage to inhibit the growth of the {001} face and promote the exposure of the {101} face, wherein the {101} face is the side face of the precursor primary particle, the thicker the side face, the greater the corresponding width, and the smaller the corresponding aspect ratio; however, the second crystal face directing agent should not be added in too large an amount, otherwise the cost will be increased and the improvement effect will not be obvious.

[0041] Preferably, the second crystal face directing agent comprises urea and / or ethylenediamine.

[0042] Preferably, the second crystal face directing agent is urea, which can not only hydrolyze to generate NH3·H2O and CO3 2- , but also can be adsorbed on the {001} face to inhibit the growth thereof and form the {101} face dominated spherical precursor.

[0043] It should be noted that the first crystal face directing agent and the second crystal face directing agent can be added to the reaction system in the same direction as other raw materials, or can be added to the reaction system at one time, or can be mixed with other raw materials (for example, added to the nickel-cobalt-manganese metal salt solution).

[0044] Preferably, after the morphology guiding reaction of step (3), centrifugation, washing, drying and sieving are further performed.

[0045] Preferably, the feeding speed of the nickel-cobalt-manganese metal source solution in steps (1)-(3) is 20L / h-40L / h, for example, can be 20L / h, 30L / h or 40L / h, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0046] Preferably, the width of the primary particle of the ternary precursor in step (3) is greater than 350nm, for example, can be 350nm, 400nm, 450nm, 500nm, 550nm, 600nm, 650nm or 700nm, but is not limited to the listed values, and other values not listed in the value range are also applicable, preferably 350nm-700nm, and more preferably 400nm-500nm.

[0047] Preferably, the aspect ratio of the primary particle of the ternary precursor in step (3) is ≤2, for example, can be 1.5, 1.6, 1.7, 1.8, 1.9 or 2.0, but is not limited to the listed values, and other values not listed in the value range are also applicable, preferably 1.5-2.0.

[0048] Preferably, the particle size D50 of the ternary precursor in step (3) is 2.5 μm to 8 μm, for example, can be 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm or 8 μm, but not limited to the listed values, other values not listed in the value range are also applicable, preferably 3.5 μm to 4.0 μm.

[0049] Preferably, the BET of the ternary precursor in step (3) is ≤ 5 m 2 / g, for example, can be 3 m 2 / g, 3.5 m 2 / g, 4 m 2 / g, 4.5 m 2 / g or 5 m 2 / g, but not limited to the listed values, other values not listed in the value range are also applicable, preferably 3 m 2 / g to 5 m 2 / g.

[0050] Preferably, the TD of the ternary precursor in step (3) is ≥ 1.7 g / cm 3 , for example, can be 1.7 g / cm 3 , 1.8 g / cm 3 , 1.9 g / cm 3 or 2.0 g / cm 3 , but not limited to the listed values, other values not listed in the value range are also applicable, preferably 1.7 g / cm 3 to 2.0 g / cm 3 .

[0051] In a second aspect, the present application provides a ternary precursor prepared by the preparation method of the first aspect.

[0052] In a third aspect, the present application provides a positive electrode material, and the precursor for preparing the positive electrode material includes the ternary precursor of the second aspect.

[0053] In a fourth aspect, the present application provides a battery including the positive electrode material of the third aspect.

[0054] Compared with the prior art, the present application has the following beneficial effects:

[0055] The application firstly adopts reverse addition, and passes the nickel-cobalt-manganese metal source solution into the first precipitator solution. On the one hand, compared with passing the first precipitator solution into the nickel-cobalt-manganese metal source solution, the pH of the system is high, the particle size of the crystal nucleus is small under high pH, and the experimental stability is higher. On the other hand, in the reverse addition process, the pH gradually decreases from high, the orientation of the primary particles gradually changes, the crystal face of the layered hydroxide gradually grows from the {001} face to the {101} face, which is beneficial to form granular primary particles instead of amorphous lamellar, so that the granular amorphous crystal nucleus with good dispersity can be obtained. Then, the complexing agent solution is added, and then the materials are passed into the growth stage in parallel flow, so that the granular amorphous crystal nucleus grows into a thick hexagonal sheet. When the solid content of the system is more than 700 g / L, the morphology guiding reaction is carried out. The gap between the primary particles is gradually filled, the morphology changes to a polyhedron, and the aspect ratio can be reduced to less than 2. If the solid content is less than 700 g / L, the primary particles are only slightly thick hexagonal sheets, and the aspect ratio is still greater than 2. Therefore, through the cooperation of each stage, the primary particles of the ternary precursor can be polyhedral structure, and part of the primary particles are similar to octahedral structure. At the same time, the prepared ternary precursor has high tap density, small aspect ratio and many active crystal faces, which is beneficial to improve the electrochemical performance of the positive electrode material. BRIEF DESCRIPTION OF DRAWINGS

[0056] Figure 1 The SEM image of the crystal nucleus obtained in step (1) in Example 1 of the application.

[0057] Figure 2 The SEM image of the product obtained in step (2) in Example 1 of the application.

[0058] Figure 3 The SEM image of the ternary precursor obtained in Example 1 of the application.

[0059] Figure 4 The CP image of the ternary precursor obtained in Example 1 of the application.

[0060] Figure 5 The SEM image of the crystal nucleus obtained in step (1) in Comparative Example 1 of the application.

[0061] Figure 6 The SEM image of the ternary precursor obtained in Comparative Example 1 of the application. DETAILED DESCRIPTION

[0062] The technical solutions of the application will be further described through specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the application, and should not be regarded as specific limitation on the application.

[0063] Example 1

[0064] The embodiment provides a preparation method of a ternary precursor, and the preparation method comprises the following steps:

[0065] (1) nucleus preparation: a reverse addition method is used, pure water and a 10 mol / L sodium hydroxide solution are added into a reaction kettle to obtain a first precipitant solution with a pH of 12.8, stirring is started, the reaction temperature is controlled to be 50 DEG C, and nitrogen is continuously introduced into the reaction kettle to prevent oxidation; then a nickel-cobalt-manganese metal sulfate solution with a total metal ion concentration of 2 mol / L is introduced into the first precipitant solution for 1 h, so that the pH of the system is reduced to 10.5, and a crystal nucleus slurry is obtained, wherein the SEM diagram of the crystal nucleus is as shown in Figure 1 It can be seen from Figure 1 that the primary particles are granular, and the secondary particles have no definite shape;

[0066] In the nickel-cobalt-manganese metal sulfate solution, the molar ratio of nickel ions, cobalt ions and manganese ions is 0.6:0.2:0.2, and the introduction speed of the nickel-cobalt-manganese metal sulfate solution is 30 L / h;

[0067] (2) growth: ammonia water is added into the crystal nucleus slurry in step (1) to make the ammonia concentration of the system be 4 g / L, then the nickel-cobalt-manganese metal sulfate solution in step (1) (the addition speed is 30 L / h), a sodium hydroxide solution, ammonia water and a cetyltrimethylammonium bromide solution are added in parallel flow, stirring and a nitrogen atmosphere are kept, the reaction temperature is controlled to be 60 DEG C, the pH is maintained at 10.8, the ammonia concentration in the system is maintained at 4 g / L, a concentrator is continuously concentrated, and a growth reaction is performed for 40 h, and the SEM diagram of the obtained product is as shown in Figure 2 It can be seen from Figure 2 that the primary particles gradually grow thick, and the secondary particles are still relatively loose;

[0068] In the system of the growth reaction, the concentration of the cetyltrimethylammonium bromide is 0.1 g / L;

[0069] (3) morphology guiding: when the solid content of the system reaches 850 g / L in the growth reaction, the reaction parameters in the growth stage are kept (the cetyltrimethylammonium bromide solution does not need to be added), the nickel-cobalt-manganese metal sulfate solution in step (1), the sodium hydroxide solution, the ammonia water and a urea solution are continuously added in parallel flow, concentration is simultaneously performed, a morphology guiding reaction is performed for 60 h, in the system of the morphology guiding reaction, the concentration of the urea is 0.1 g / L, finally, centrifugation, washing, drying and sieving are performed, and the ternary precursor is obtained, and the chemical formula of the ternary precursor is Ni 0.6 Co 0.2 Mn 0.2 (OH)2;

[0070] The SEM diagram of the ternary precursor obtained in the embodiment is as shown in Figure 3 It can be seen fromFigure 3 It can be seen that the primary particles grow into polyhedral morphology, and the surface of the secondary particles is dense; the CP diagram of the ternary precursor obtained in this example is shown in FIG. 1. Figure 4 It can be seen that the particles are compact inside. Figure 4 It can be seen that the particles are compact inside.

[0071] Example 2

[0072] The example provides a preparation method of a ternary precursor, which comprises the following steps:

[0073] (1) Nucleation: a reverse addition method is used, pure water and a 10 mol / L sodium hydroxide solution are added into a reaction kettle to obtain a first precipitant solution with a pH of 12.8, stirring is started, the reaction temperature is controlled at 50°C, and nitrogen is continuously introduced into the reaction kettle to prevent oxidation; then a nickel-cobalt-manganese metal sulfate solution with a total metal ion concentration of 2 mol / L is introduced into the first precipitant solution for 1 h, so that the pH of the system is reduced to 10.5, and a crystal nucleus slurry is obtained;

[0074] In the nickel-cobalt-manganese metal sulfate solution, the molar ratio of nickel ions, cobalt ions and manganese ions is 0.6:0.2:0.2, and the introduction speed of the nickel-cobalt-manganese metal sulfate solution is 30 L / h;

[0075] (2) Growth: ammonia water is added into the crystal nucleus slurry in step (1) to make the ammonia concentration of the system be 4 g / L, then the nickel-cobalt-manganese metal sulfate solution in step (1) (the addition speed is 30 L / h), a sodium hydroxide solution, ammonia water and a cetyltrimethylammonium bromide solution are added in parallel flow, stirring and a nitrogen atmosphere are maintained, the reaction temperature is controlled at 60°C, the pH is maintained at 10.8, the ammonia concentration in the system is maintained at 4 g / L, a concentrator is continuously concentrated, and a growth reaction is performed for 40 h;

[0076] In the system of the growth reaction, the concentration of cetyltrimethylammonium bromide is 0.05 g / L;

[0077] (3) Morphology guiding: when the solid content of the system reaches 850 g / L in the growth reaction, the reaction parameters in the growth stage are maintained (without adding the cetyltrimethylammonium bromide solution), the nickel-cobalt-manganese metal sulfate solution in step (1), the sodium hydroxide solution, the ammonia water and a urea solution are continuously added in parallel flow, concentration is simultaneously performed, a morphology guiding reaction is performed for 60 h, in the system of the morphology guiding reaction, the concentration of urea is 0.05 g / L, finally the ternary precursor is obtained after centrifugation, washing, drying and sieving, and the chemical formula of the ternary precursor is Ni 0.6 Co 0.2 Mn 0.2 (OH)2.

[0078] Example 3

[0079] The embodiment provides a preparation method of a ternary precursor, and the preparation method comprises the following steps:

[0080] (1) Nucleus preparation: by using reverse addition method, pure water and 10 mol / L sodium hydroxide solution are added into a reaction kettle to obtain a first precipitant solution with pH of 12.8, stirring is started, the reaction temperature is controlled to be 50 DEG C, and nitrogen is continuously introduced into the reaction kettle to prevent oxidation; then a nickel-cobalt-manganese metal sulfate solution with a total metal ion concentration of 2 mol / L is introduced into the first precipitant solution for 1 h, so that the pH of the system is reduced to 10.5, and a crystal nucleus slurry is obtained;

[0081] In the nickel-cobalt-manganese metal sulfate solution, the molar ratio of nickel ions, cobalt ions and manganese ions is 0.6:0.1:0.3, and the introduction speed of the nickel-cobalt-manganese metal sulfate solution is 30 L / h;

[0082] (2) Growth: ammonia water is added into the crystal nucleus slurry in step (1) to make the ammonia concentration of the system be 4 g / L, then the nickel-cobalt-manganese metal sulfate solution in step (1) (the introduction speed is 30 L / h), sodium hydroxide solution and ammonia water are added in parallel flow, stirring and nitrogen atmosphere are kept, the reaction temperature is controlled to be 60 DEG C, the pH is kept at 10.8, the ammonia concentration in the system is kept at 4 g / L, a concentrator is continuously concentrated, and the growth reaction is carried out for 38 h;

[0083] (3) Morphology guiding: when the solid content of the system reaches 800 g / L in the growth reaction, the reaction parameters in the growth stage are kept, the nickel-cobalt-manganese metal sulfate solution in step (1), sodium hydroxide solution, ammonia water and urea solution are continuously added in parallel flow, concentration is simultaneously carried out, the morphology guiding reaction is carried out for 55 h, in the morphology guiding reaction, the concentration of urea in the system is 0.05 g / L, finally, the ternary precursor is obtained through centrifugation, washing, drying and sieving, and the chemical formula of the ternary precursor is Ni 0.6 Co 0.1 Mn 0.3 (OH)2.

[0084] Example 4

[0085] The embodiment provides a preparation method of a ternary precursor, and the preparation method comprises the following steps:

[0086] (1) Nucleus preparation: by using reverse addition method, pure water and 10 mol / L sodium hydroxide solution are added into a reaction kettle to obtain a first precipitant solution with pH of 12.4, stirring is started, the reaction temperature is controlled to be 50 DEG C, and nitrogen is continuously introduced into the reaction kettle to prevent oxidation; then a nickel-cobalt-manganese metal sulfate solution with a total metal ion concentration of 2 mol / L is introduced into the first precipitant solution for 0.5 h, so that the pH of the system is reduced to 10.5, and a crystal nucleus slurry is obtained;

[0087] The molar ratio of nickel ions, cobalt ions and manganese ions in the nickel-cobalt-manganese metal sulfate solution is 0.6:0.1:0.3, and the feeding speed of the nickel-cobalt-manganese metal sulfate solution is 30 L / h;

[0088] (2) Growth: ammonia water is added to the crystal nucleus slurry of step (1) to make the ammonia concentration of the system 3.5 g / L, then the nickel-cobalt-manganese metal sulfate solution of step (1) (the feeding speed is 30 L / h), sodium hydroxide solution, ammonia water and cetyltrimethylammonium bromide solution are added in parallel flow, stirring and nitrogen atmosphere are maintained, the reaction temperature is controlled at 65°C, the pH is maintained at 10.6, the ammonia concentration in the system is maintained at 3.5 g / L, the concentration machine is continuously concentrated, and the growth reaction is carried out for 38 h;

[0089] The concentration of cetyltrimethylammonium bromide in the system of the growth reaction is 0.1 g / L;

[0090] (3) Morphology guiding: when the solid content of the system reaches 800 g / L, the reaction parameters of the growth stage are maintained (without adding cetyltrimethylammonium bromide solution), the nickel-cobalt-manganese metal sulfate solution of step (1), sodium hydroxide solution, ammonia water and urea solution are continuously added in parallel flow, and concentration is carried out at the same time, the morphology guiding reaction is carried out for 55 h, the concentration of urea in the system of the morphology guiding reaction is 0.1 g / L, and finally the ternary precursor is obtained after centrifugation, washing, drying and sieving, the chemical formula of the ternary precursor is Ni 0.6 Co 0.1 Mn 0.3 (OH)2.

[0091] Example 5

[0092] The embodiment provides a preparation method of a ternary precursor, and the preparation method comprises the following steps:

[0093] (1) Nucleation: a first precipitant solution with pH of 12.4 is obtained by adding pure water and 10 mol / L sodium hydroxide solution into a reaction kettle, stirring is started, the reaction temperature is controlled at 50°C, and nitrogen is continuously introduced into the reaction kettle to prevent oxidation; then a nickel-cobalt-manganese metal sulfate solution with a total metal ion concentration of 2 mol / L is introduced into the first precipitant solution for 0.5 h, so that the pH of the system is reduced to 10.5, and a crystal nucleus slurry is obtained;

[0094] The molar ratio of nickel ions, cobalt ions and manganese ions in the nickel-cobalt-manganese metal sulfate solution is 0.7:0.1:0.2, and the feeding speed of the nickel-cobalt-manganese metal sulfate solution is 30 L / h;

[0095] (2) Growth: ammonia water was added to the crystal nucleus slurry of step (1) to make the ammonia concentration of the system 3.5 g / L, then the nickel-cobalt-manganese metal sulfate solution of step (1) (the adding speed was 30 L / h), sodium hydroxide solution, ammonia water and polyethylene glycol solution were added in parallel flow, stirring and nitrogen atmosphere were maintained, the reaction temperature was controlled at 65℃, the pH was maintained at 10.6, the ammonia concentration in the system was maintained at 3.5 g / L, the concentrator was started to continuously concentrate, and the growth reaction was carried out;

[0096] The concentration of polyethylene glycol in the system of the growth reaction was 0.2 g / L;

[0097] (3) Morphology guiding: the growth reaction was carried out until the solid content of the system reached 850 g / L, the reaction parameters of the growth stage were maintained (polyethylene glycol solution was not added), the nickel-cobalt-manganese metal sulfate solution of step (1), sodium hydroxide solution, ammonia water and urea solution were continuously added in parallel flow, and concentration was carried out at the same time, the morphology guiding reaction was carried out for 62 h, the concentration of urea in the system of the morphology guiding reaction was 0.2 g / L, finally the ternary precursor was obtained after centrifugation, washing, drying and sieving, the chemical formula of the ternary precursor was Ni 0.7 Co 0.1 Mn 0.2 (OH)2.

[0098] Example 6

[0099] The embodiment provides a preparation method of a ternary precursor, and the preparation method comprises the following steps:

[0100] (1) Nucleus preparation: by reverse addition method, pure water and 10 mol / L sodium hydroxide solution were added into a reaction kettle to obtain a first precipitant solution with pH of 12.4, stirring was started, the reaction temperature was controlled at 50℃, and nitrogen was continuously introduced into the reaction kettle to prevent oxidation; then a nickel-cobalt-manganese metal sulfate solution with a total metal ion concentration of 2 mol / L was introduced into the first precipitant solution for 0.5 h, so that the pH of the system was reduced to 10.5, and a crystal nucleus slurry was obtained;

[0101] The molar ratio of nickel ions, cobalt ions and manganese ions in the nickel-cobalt-manganese metal sulfate solution was 0.7:0.1:0.2, and the introduction speed of the nickel-cobalt-manganese metal sulfate solution was 30 L / h;

[0102] (2) Growth: ammonia water was added to the crystal nucleus slurry of step (1) to make the ammonia concentration of the system 3.5 g / L, then the nickel-cobalt-manganese metal sulfate solution of step (1) (the adding speed was 30 L / h), sodium hydroxide solution, ammonia water and polyethylene glycol solution were added in parallel flow, stirring and nitrogen atmosphere were maintained, the reaction temperature was controlled at 65℃, the pH was maintained at 10.6, the ammonia concentration in the system was maintained at 3.5 g / L, the concentrator was started to continuously concentrate, and the growth reaction was carried out for 40 h;

[0103] The concentration of polyethylene glycol in the system of the growth reaction is 0.2 g / L;

[0104] (3) Morphology guiding: the solid content of the system of the growth reaction reaches 850 g / L, the reaction parameters of the growth stage are kept (polyethylene glycol solution is not added), the nickel-cobalt-manganese metal sulfate solution, the sodium hydroxide solution and the ammonia water in step (1) are continuously and uniformly added, and the morphology guiding reaction is continuously performed for 62 h, finally, the ternary precursor is obtained after centrifugation, washing, drying and sieving, the chemical formula of the ternary precursor is Ni 0.7 Co 0.1 Mn 0.2 (OH)2.

[0105] Example 7

[0106] The preparation method of the ternary precursor provided in the embodiment is the same as that in Example 1, except that, in step (3), the solid content of the system of the growth reaction reaches 700 g / L, and the morphology guiding in step (3) is performed.

[0107] Example 8

[0108] The preparation method of the ternary precursor provided in the embodiment is the same as that in Example 1, except that, in step (2), the cetyltrimethylammonium bromide solution is not added.

[0109] Example 9

[0110] The preparation method of the ternary precursor provided in the embodiment is the same as that in Example 1, except that, in step (2), the concentration of cetyltrimethylammonium bromide in the system of the growth reaction is 1 g / L.

[0111] Example 10

[0112] The preparation method of the ternary precursor provided in the embodiment is the same as that in Example 1, except that, in step (3), the urea solution is not added.

[0113] Example 11

[0114] The preparation method of the ternary precursor provided in the embodiment is the same as that in Example 1, except that, in step (3), the concentration of urea in the system of the morphology guiding reaction is 1 g / L.

[0115] Example 12

[0116] The embodiment provides a preparation method of a ternary precursor, which is the same as that in the embodiment 1, except that no cetyltrimethylammonium bromide solution is added in step (2), and no urea solution is added in step (3).

[0117] Comparative example 1

[0118] The comparative example provides a preparation method of a ternary precursor, which is the same as that in the embodiment 1, except that the crystal nucleus is prepared by using the normal addition method in step (1), that is, the first precipitant solution is added into the nickel-cobalt-manganese metal sulfate solution.

[0119] The SEM image of the crystal nucleus obtained in step (1) of the comparative example is shown in Figure 5 , and Figure 5 It can be seen that the primary particles are not granular, but lamellar, and it is difficult to grow into thick hexagonal sheets subsequently; the SEM image of the ternary precursor obtained in the comparative example is shown in Figure 6 , and Figure 6 It can be seen that the primary particles of the obtained ternary precursor are lamellar, and part of the primary particles are slightly regular hexagonal sheets, but the thickness of the hexagonal sheets is obviously thinner than that in the embodiment 1. Figure 3

[0120] Comparative example 2

[0121] The comparative example provides a preparation method of a ternary precursor, which is the same as that in the embodiment 1, except that the morphology guiding in step (3) is performed after the solid content of the system reaches 600 g / L in the growth reaction in step (3).

[0122] The particle size D50, BET, TD, width of primary particles and aspect ratio of primary particles of the ternary precursors obtained in the above embodiment and comparative examples are tested, wherein the particle size D50 of the ternary precursor is tested by using a Malvern particle size analyzer, the BET of the ternary precursor is tested by using a specific surface area analyzer, the TD of the ternary precursor is tested by using a tap density instrument, the length and width of the primary particles are measured by analyzing the SEM image of the ternary precursor by using Nano Measurer software, and the aspect ratio of the primary particles is calculated.

[0123] The ternary precursors obtained in the above embodiment and comparative examples are mixed with lithium carbonate (the molar ratio of the total metal ions in the ternary precursor to lithium ions in the lithium carbonate is 1:1.05), and then sintered at 900 ℃ for 15 h to obtain a positive electrode material; the roundness of the positive electrode particles is obtained by analyzing the SEM image of the positive electrode material by using IPWIN software; and the tap density of the positive electrode material at 5T is tested by using a tap density instrument.

[0124] ​The positive electrode material prepared above is prepared into a battery, and 100 cycles are carried out at 1C and 2.7-4.3V to obtain the 100-cycle capacity retention rate. The preparation of the battery comprises the following steps: taking the positive electrode material, acetylene black and PVDF in a mass ratio of 8:1:1, mixing uniformly to prepare a slurry with N-methylpyrrolidone as a solvent, coating the slurry on an aluminum foil, and vacuum drying. Then, a lithium metal piece is used as a negative electrode, a polypropylene film is used as a separator, LiPF6-EC / DMC is used as an electrolyte, and the battery is assembled in a glove box.

[0125] The test results are shown in Table 1 below:

[0126] Table 1

[0127]

[0128] From the above Table 1, it can be seen that:

[0129] It can be seen from Examples 1-6 and Comparative Example 1 that the present application adopts a reverse addition method in the preparation of crystal nuclei, which is conducive to the formation of granular primary particles and preferential growth to the {101} plane, thereby reducing the BET of the ternary precursor and the aspect ratio of the primary particles, improving the TD of the ternary precursor, the roundness and the compaction density of the positive electrode material, and the capacity retention rate of the battery; it can be seen from Examples 1-6, Example 7 and Comparative Example 2 that the present application requires a morphology guiding reaction when the solid content of the system is above 700g / L, and Comparative Example 2 performs a morphology guiding reaction at a low solid content, resulting in only slightly thick hexagonal plate-like primary particles with an aspect ratio greater than 2, which leads to the deterioration of the physical properties of the ternary precursor and the positive electrode material and the decline of the cycle performance of the battery; it can be seen from Examples 1, Example 8, Example 10 and Example 12 that the addition of the first crystal face directing agent during the growth reaction in step (2) and the addition of the second crystal face directing agent during the morphology guiding reaction in step (2) can inhibit the growth of the {001} plane and promote the exposure of the {101} plane, thereby being conducive to reducing the aspect ratio of the primary particles of the ternary precursor, and preferably adding the crystal face directing agent at least in one of the growth stage and the morphology guiding stage, otherwise the physical properties of the ternary precursor and the positive electrode material will be greatly deteriorated, and the cycle performance of the battery will be affected; it can be seen from Examples 1, Example 9 and Example 11 that when the amount of the first crystal face directing agent and the second crystal face directing agent is too much, the cost will be increased and the improvement effect will not be obvious.

[0130] The above merely describes specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and those skilled in the art should understand that any changes or replacements within the technical scope disclosed by the present application can be easily thought of by those skilled in the art, and all fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for preparing a ternary precursor, characterized in that, The preparation method includes the following steps: (1) The nickel-cobalt-manganese metal source solution is passed into the first precipitant solution to carry out the nucleation reaction and obtain the crystal nucleus slurry; (2) First, add a complexing agent solution to the crystal nucleus slurry described in step (1), and then introduce the nickel-cobalt-manganese metal source solution, the second precipitant solution and the complexing agent solution in parallel to carry out the growth reaction; (3) When the growth reaction described in step (2) reaches a solid content of more than 700 g / L, a morphology-guided reaction is carried out to obtain the ternary precursor.

2. The preparation method according to claim 1, characterized in that, Step (1) The pH of the first precipitant solution is 12~13; Preferably, the temperature of the nucleation reaction in step (1) is 40℃~60℃; Preferably, the time for bubbling the nickel-cobalt-manganese metal source solution into the first precipitant solution in step (1) is 0.5h to 3h; Preferably, after the nucleation reaction in step (1) is completed, the pH of the system drops to 10-11.

3. The preparation method according to claim 1 or 2, characterized in that, In the nickel-cobalt-manganese metal source solution described in steps (1) and (2), the molar ratio of nickel ions, cobalt ions and manganese ions is x:y:(1-xy), where 0.5≤x≤0.8, 0.05≤y≤0.3, and 1-xy≥0. Preferably, the total metal ion concentration of the nickel-cobalt-manganese metal source solution in steps (1) and (2) is 0.5 mol / L to 2 mol / L.

4. The preparation method according to claim 1 or 2, characterized in that, A first crystal plane guiding agent was also added during the growth reaction described in step (2); Preferably, in the growth reaction system described in step (2), the concentration of the first crystal plane guiding agent is 0 g / L to 1 g / L, and more preferably 0.05 g / L to 0.2 g / L; Preferably, the first crystal plane guiding agent comprises any one or a combination of at least two of octadecylphosphonic acid, dodecylphosphonic acid, vinylphosphonic acid, sodium dodecylbenzenesulfonate, hexadecyltrimethylammonium bromide, polyethylene glycol, or polyvinylpyrrolidone.

5. The preparation method according to claim 1 or 2, characterized in that, In step (2), the concentration of the complexing agent in the system is increased to 2 g / L to 6 g / L by adding the complexing agent solution. Preferably, the temperature of the growth reaction in step (2) is 50℃~80℃, and the pH is 10~11; Preferably, in the growth reaction system described in step (2), the concentration of the complexing agent is 2 g / L to 6 g / L; Preferably, the concentration process is continuously carried out during the growth reaction in step (2); Preferably, in step (2), the concentration of the second precipitant solution is 5 mol / L to 10 mol / L.

6. The preparation method according to claim 1 or 2, characterized in that, When the growth reaction described in step (2) reaches a solid content of 700 g / L to 1000 g / L, a morphology-guided reaction is carried out. Preferably, the morphology-guided reaction time in step (3) is 40h~80h; Preferably, a second crystal plane guiding agent is added during the morphology-guided reaction in step (3); Preferably, in the morphology-guided reaction system described in step (3), the concentration of the second crystal plane guiding agent is 0 g / L to 1 g / L, preferably 0.05 g / L to 0.2 g / L; Preferably, the second crystal plane guiding agent comprises urea and / or ethylenediamine.

7. The preparation method according to claim 1 or 2, characterized in that, The width of the primary particles of the ternary precursor in step (3) is above 350 nm, preferably 350 nm to 700 nm, and more preferably 400 nm to 500 nm; Preferably, the aspect ratio of the primary particles of the ternary precursor in step (3) is ≤2, and more preferably 1.5~2.0; Preferably, the particle size D50 of the ternary precursor in step (3) is 2.5 μm to 8 μm, and more preferably 3.5 μm to 4.0 μm; Preferably, the BET of the ternary precursor in step (3) is ≤5m. 2 / g, preferably 3m 2 / g~5m 2 / g; Preferably, the TD of the ternary precursor in step (3) is ≥1.7 g / cm³. 3 The preferred value is 1.7 g / cm³. 3 ~2.0g / cm 3 .

8. A ternary precursor, characterized in that, The ternary precursor is prepared by the preparation method according to any one of claims 1-7.

9. A positive electrode material, characterized in that, The precursor for preparing the cathode material includes the ternary precursor as described in claim 8.

10. A battery, characterized in that, The battery includes the positive electrode material as described in claim 9.

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