A ternary precursor, a preparation method thereof, a positive electrode material and a battery

Abstract

The application provides a ternary precursor, a preparation method of the ternary precursor, a positive electrode material and a battery. The preparation method comprises the following steps: passing 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; first, a complexing agent solution is added to the crystal nucleus slurry, and then the nickel-cobalt-manganese metal source solution, a second precipitant solution and the complexing agent solution are passed in parallel to perform a growth reaction; when the solid content of the system is greater than or equal to 700 g / L, a morphology guiding reaction is performed, so as to obtain the ternary precursor. According to the preparation method, the crystal nucleus is prepared by a reverse addition method, then the crystal nucleus is grown into a thick hexagonal sheet, and finally the morphology guiding is performed under high solid content, so that the ternary precursor with high tap density, small length-width ratio and many active crystal faces is formed, and the electrochemical performance of the positive electrode material is improved.

Description

Technical Field

[0001] This invention belongs to the field of battery technology and relates to a ternary precursor and its preparation method, cathode material and battery. Background Technology

[0002] Lithium-ion batteries are widely used in new energy electric vehicles, digital products, and mobile phones due to their high operating voltage, high energy density, and long cycle life. However, with the rapid development of industries such as electric vehicles, the requirements for the energy density and cycle life of lithium-ion batteries are becoming increasingly stringent. Ternary cathode materials, due to their high capacity and correspondingly high battery energy density, have attracted widespread attention.

[0003] Ternary precursors are key raw materials for preparing ternary cathode materials. Due to the inheritance of cathode materials from their precursors, the particle size distribution, microstructure, and crystal structure of the precursors directly determine the particle size distribution, microstructure, and crystal structure of the battery cathode material. Among these, the crystal orientation and aspect ratio of the primary particles in the ternary precursor have a significant impact on the morphology of the sintered cathode material, further affecting its compaction density and cycle performance. Therefore, controlling the crystal growth of the primary particles in the ternary precursor is of great importance. While conventional crystal orientation control methods, through controlling reaction parameters and using additives, can obtain ternary precursors with different proportions of active crystal faces, generally, the primary particles are mostly hexagonal plates, differing only in thickness from conventional precursors, with aspect ratios generally greater than 2. This results in insufficient improvement in the sphericity and compaction density of the cathode material, limiting the improvement in electrical performance.

[0004] Based on the above research, there is a need to provide a method for preparing ternary precursors that can further control the primary particle morphology of ternary precursors and improve the roundness, compaction density and electrochemical performance of cathode materials. Summary of the Invention

[0005] The purpose of this invention is to provide a ternary precursor and its preparation method, a cathode material, and a battery. The preparation method involves preparing crystal nuclei through an inverse addition process, then allowing the crystal nuclei to grow into thick hexagonal plates, and finally guiding the morphology under high solid content to form a ternary precursor with high tap density, small aspect ratio, and many active crystal faces, thereby improving the electrochemical performance of the cathode material.

[0006] To achieve this objective, the present invention employs the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing a ternary precursor, the method comprising the following steps:

[0008] (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;

[0009] (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;

[0010] (3) When the growth reaction described in step (2) reaches a solid content of 700 g / L or more (e.g., 700 g / L, 800 g / L, 900 g / L or 1000 g / L), a morphology-guided reaction is carried out to obtain the ternary precursor.

[0011] This invention first employs a reverse addition method, in which a nickel-cobalt-manganese metal source solution is passed into a first precipitant solution. On one hand, because the nickel-cobalt-manganese metal source solution is passed into the first precipitant solution, compared to passing the first precipitant solution directly into the nickel-cobalt-manganese metal source solution, the pH of the system is higher. At higher pH, the crystal nuclei are smaller, resulting in higher experimental stability. On the other hand, during the reverse addition process, the pH gradually decreases, and the orientation of the primary particles gradually changes. The layered hydroxide crystals preferentially grow from the {001} plane towards the {101} plane, which is beneficial for forming granular primary particles rather than amorphous lamellar structures, thus obtaining well-dispersed granular amorphous crystal nuclei. Then, a complexing agent solution is added first, followed by a co-current flow... When the feedstock enters the growth stage, the granular amorphous crystal nuclei grow into thick hexagonal plates. When the solid content of the system reaches above 700 g / L, a morphology-guided reaction is carried out, and the gaps between the primary particles are gradually filled, and the morphology transforms into a polyhedron, with the aspect ratio dropping below 2. However, if the solid content is less than 700 g / L, the primary particles are only slightly thicker hexagonal plates, and the aspect ratio is still greater than 2. Therefore, through the cooperation of each stage, this invention can make the primary particles of the ternary precursor have a polyhedral structure, with some primary particles resembling an octahedral structure. At the same time, the prepared ternary precursor has a high tap density, a small aspect ratio, and many active crystal faces, which is beneficial to improving the electrochemical performance of the cathode material.

[0012] As mentioned above, the ternary precursor of the present invention preferentially grows towards the {101} facet, thus exposing more {101} facets, i.e., the side faces. This results in a smaller dimensional difference between the thickness and diameter directions of the primary particles, more uniform sintering shrinkage, and stronger bonding between the primary particles, making it less prone to local collapse. Ultimately, this yields a cathode material with a smoother surface, a more rounded shape, and a higher compaction density. In addition, the {101} facet is the main channel for lithium-ion insertion and extraction. The higher its proportion, the better it is for improving the lithium-ion insertion and extraction capability, thereby further improving the electrochemical performance of the cathode material.

[0013] It should be noted that the preparation method described in this invention is carried out in a reaction vessel under stirring conditions, and a protective gas (such as nitrogen) is continuously introduced into the vessel to prevent oxidation.

[0014] Preferably, the pH of the first precipitant solution in step (1) is 12 to 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. Other unlisted values ​​within the range are also applicable.

[0015] Preferably, the first precipitant solution in step (1) and the second precipitant solution in step (2) each independently comprise 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) includes ammonia.

[0018] Preferably, the temperature of the nucleation reaction in step (1) is 40℃~60℃, for example, it can be 40℃, 45℃, 50℃, 55℃ or 60℃, but is not limited to the listed values. Other unlisted values ​​within the 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 0.5h to 3h, for example, it can be 0.5h, 1h, 1.5h, 2h, 2.5h or 3h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] Preferably, after the nucleation reaction in step (1) is completed, the pH of the system drops 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. Other unlisted values ​​within the range are also applicable.

[0021] Preferably, 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 1-xy≥0, 0.5≤x≤0.8 (e.g., 0.5, 0.6, 0.7, or 0.8), and 0.05≤y≤0.3 (e.g., 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. Other unlisted values ​​within the range are also applicable.

[0022] 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, for example, it can be 0.5 mol / L, 1 mol / L, 1.5 mol / L or 2 mol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

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

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

[0025] 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, 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. Other unlisted values ​​within the range are also applicable, preferably 0.05 g / L to 0.2 g / L.

[0026] In the growth stage, the present invention can add a first crystal plane guiding agent to inhibit the growth of the {001} plane and promote the exposure of the {101} plane. The {101} plane is the side of the primary particle of the precursor. The thicker the side, the larger the corresponding width, and the smaller the corresponding aspect ratio. However, the amount of the first crystal plane guiding agent added should not be too much. Adding too much will increase the cost and the improvement effect will not be obvious.

[0027] 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.

[0028] Preferably, the concentration of the complexing agent in the system added in 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. Other unlisted values ​​within the range are also applicable.

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

[0030] Preferably, the growth reaction time in step (2) is 30h to 50h, for example, it can be 30h, 35h, 40h, 45h or 50h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0031] Preferably, in the growth reaction system described in step (2), the concentration of the complexing agent 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. Other unlisted values ​​within the range are also applicable.

[0032] Preferably, the concentration process is continuously carried out during the growth reaction in step (2).

[0033] Preferably, in step (2), the concentration of the second precipitant solution is 5 mol / L to 10 mol / L, for example, it can be 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L or 10 mol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0034] Preferably, in step (2), the growth reaction is carried out when the solid content of the system is 700 g / L to 1000 g / L (for example, it can be 700 g / L, 800 g / L, 900 g / L or 1000 g / L), and a morphology-guided reaction is performed.

[0035] The solid content of the system in the morphology guidance stage of this invention needs to reach more than 700 g / L, but if the solid content is too high, the concentrator will have difficulty handling it.

[0036] It should be noted that during the morphology-guided reaction in step (3), the reaction parameters of the growth stage in step (2) are maintained, and the feed and concentration continue to be carried out in parallel. That is, the temperature, pH and complexing agent concentration in the system of the morphology-guided reaction in step (3) are the same as those of the growth reaction in step (2).

[0037] Preferably, the morphology-guided reaction time in step (3) is 40h to 80h, for example, it can be 40h, 50h, 60h, 70h or 80h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0038] Preferably, a second crystal plane guiding agent is added during the morphology-guided reaction in step (3).

[0039] Preferably, in the morphology-guided reaction system described in step (3), the concentration of the second crystal plane guide agent 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. Other unlisted values ​​within the range are also applicable, preferably 0.05 g / L to 0.2 g / L.

[0040] In the morphology guidance stage, a second crystal plane guide agent can be added to inhibit the growth of the {001} plane and promote the exposure of the {101} plane. The {101} plane is the side surface of the primary particles of the precursor. The thicker the side surface, the larger the corresponding width, and the smaller the corresponding aspect ratio. However, the amount of the second crystal plane guide agent added should not be too much. Adding too much will increase the cost significantly and the improvement effect will not be obvious.

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

[0042] The second crystal plane guiding agent of this invention is preferably urea, which can be hydrolyzed to generate NH3·H2O and CO3. 2- It can also be adsorbed onto the {001} surface, inhibiting its growth and forming a spherical precursor dominated by the {101} surface.

[0043] It should be noted that the first and second crystal plane guiding agents of the present invention can be added to the reaction system in a manner that is parallel to other raw materials, or can be added to the reaction system all at once, or can be mixed with other raw materials (such as adding to a nickel-cobalt-manganese metal salt solution).

[0044] Preferably, after the morphology-guided reaction described in step (3), centrifugation, washing, drying, and sieving are also performed.

[0045] Preferably, the inflow rate of the nickel-cobalt-manganese metal source solution in steps (1)-(3) is 20L / h to 40L / h, for example, it can be 20L / h, 30L / h or 40L / h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0046] Preferably, the width of the primary particles of the ternary precursor in step (3) is above 350 nm, for example, it can be 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm or 700 nm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable. Preferably, it is 350 nm to 700 nm, and more preferably 400 nm to 500 nm.

[0047] Preferably, the aspect ratio of the primary particles of the ternary precursor in step (3) is ≤2, for example, it can be 1.5, 1.6, 1.7, 1.8, 1.9 or 2.0, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 1.5~2.0.

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

[0049] Preferably, the BET of the ternary precursor in step (3) is ≤5m. 2 / g, for example, could be 3m 2 / g, 3.5m 2 / g、4m 2 / g, 4.5m 2 / g or 5m 2 / g, but not limited to the listed values; other unlisted values ​​within the range also apply, preferably 3m. 2 / g~5m 2 / g.

[0050] Preferably, the TD of the ternary precursor in step (3) is ≥1.7 g / cm³. 3 For example, it could be 1.7 g / cm³ 3 1.8g / cm 3 1.9g / cm 3 Or 2.0g / cm 3 However, this is not limited to the listed values; other unlisted values ​​within the range are also applicable, with 1.7 g / cm³ being the preferred value. 3 ~2.0g / cm 3 .

[0051] In a second aspect, the present invention provides a ternary precursor, which is prepared by the preparation method described in the first aspect.

[0052] Thirdly, the present invention provides a cathode material, wherein the precursor for preparing the cathode material includes the ternary precursor as described in the second aspect.

[0053] Fourthly, the present invention provides a battery comprising the positive electrode material as described in the third aspect.

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

[0055] This invention first employs a reverse addition method, in which a nickel-cobalt-manganese metal source solution is passed into a first precipitant solution. On one hand, because the nickel-cobalt-manganese metal source solution is passed into the first precipitant solution, compared to passing the first precipitant solution directly into the nickel-cobalt-manganese metal source solution, the pH of the system is higher. At higher pH, the crystal nuclei are smaller, resulting in higher experimental stability. On the other hand, during the reverse addition process, the pH gradually decreases, and the orientation of the primary particles gradually changes. The layered hydroxide crystals preferentially grow from the {001} plane towards the {101} plane, which is beneficial for forming granular primary particles rather than amorphous lamellar structures, thus obtaining well-dispersed granular amorphous crystal nuclei. Then, a complexing agent solution is added first, followed by a co-current flow... When the feedstock enters the growth stage, the granular amorphous crystal nuclei grow into thick hexagonal plates. When the solid content of the system reaches above 700 g / L, a morphology-guided reaction is carried out, and the gaps between the primary particles are gradually filled, and the morphology transforms into a polyhedron, with the aspect ratio dropping below 2. However, if the solid content is less than 700 g / L, the primary particles are only slightly thicker hexagonal plates, and the aspect ratio is still greater than 2. Therefore, through the cooperation of each stage, this invention can make the primary particles of the ternary precursor have a polyhedral structure, with some primary particles resembling an octahedral structure. At the same time, the prepared ternary precursor has a high tap density, a small aspect ratio, and many active crystal faces, which is beneficial to improving the electrochemical performance of the cathode material. Attached Figure Description

[0056] Figure 1 This is a SEM image of the crystal nucleus obtained in step (1) of Embodiment 1 of the present invention.

[0057] Figure 2 This is an SEM image of the product obtained in step (2) of Embodiment 1 of the present invention.

[0058] Figure 3 This is a SEM image of the ternary precursor obtained in Example 1 of the present invention.

[0059] Figure 4 This is a CP diagram of the ternary precursor obtained in Embodiment 1 of the present invention.

[0060] Figure 5 This is a SEM image of the crystal nucleus obtained in step (1) of Comparative Example 1 of the present invention.

[0061] Figure 6 This is a SEM image of the ternary precursor obtained in Comparative Example 1 of the present invention. Detailed Implementation

[0062] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0063] Example 1

[0064] This embodiment provides a method for preparing a ternary precursor, the method comprising the following steps:

[0065] (1) Nucleus preparation: Using the reverse addition method, pure water and 10 mol / L sodium hydroxide solution were added to the reactor to obtain a first precipitant solution with a pH of 12.8. Stirring was started, the reaction temperature was controlled at 50℃, and nitrogen gas was continuously introduced into the reactor 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 1 hour to lower the pH of the system to 10.5, thus obtaining the nucleus slurry. The SEM image of the nucleus is shown below. Figure 1 As shown, by Figure 1 It can be seen that primary particles are granular, while secondary particles are amorphous.

[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 influent rate of the nickel-cobalt-manganese metal sulfate solution is 30 L / h.

[0067] (2) Growth: Ammonia water was added to the crystal nucleus slurry described in step (1) to make the ammonia concentration of the system 4 g / L. Then, the nickel cobalt manganese metal sulfate solution described in step (1) (addition rate of 30 L / h), sodium hydroxide solution, ammonia water and hexadecyltrimethylammonium bromide solution were added in parallel. Stirring and nitrogen atmosphere were maintained, the reaction temperature was controlled at 60℃, the pH was maintained at 10.8, and the ammonia concentration in the system was maintained at 4 g / L. The thickener was turned on for continuous concentration, and the growth reaction was carried out for 40 h. The SEM image of the obtained product is shown below. Figure 2 As shown, by Figure 2 It can be seen that the primary particles gradually thicken, while the secondary particles remain relatively loose;

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

[0069] (3) Morphology guidance: The growth reaction continues until the solid content of the system reaches 850 g / L. The reaction parameters of the growth stage are maintained (no need to add hexadecyltrimethylammonium bromide solution). The nickel cobalt manganese metal sulfate solution, sodium hydroxide solution, ammonia water and urea solution described in step (1) are added in parallel. At the same time, the concentration is carried out and the morphology guidance reaction is carried out for 60 h. In the morphology guidance reaction system, the concentration of urea is 0.1 g / L. Finally, after centrifugation, washing, drying and sieving, the ternary precursor is obtained. The chemical formula of the ternary precursor is Ni 0.6 Co 0.2 Mn 0.2 (OH)2;

[0070] The SEM image of the ternary precursor obtained in this embodiment is as follows: Figure 3 As shown, by Figure 3 It can be seen that the primary particles grow into a polyhedral morphology, while the secondary particles have a dense surface; the CP diagram of the ternary precursor obtained in this embodiment is as follows. Figure 4 As shown, by Figure 4 It can be seen that the particles are compact inside.

[0071] Example 2

[0072] This embodiment provides a method for preparing a ternary precursor, the method comprising the following steps:

[0073] (1) Nucleus preparation: Using the reverse addition method, pure water and 10 mol / L sodium hydroxide solution were added to the reactor to obtain a first precipitant solution with a pH of 12.8. Stirring was started, the reaction temperature was controlled at 50℃, and nitrogen gas was continuously introduced into the reactor 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 1 hour to reduce the pH of the system to 10.5 and obtain the nucleus slurry.

[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 influent rate of the nickel-cobalt-manganese metal sulfate solution is 30 L / h.

[0075] (2) Growth: Add ammonia water to the crystal nucleus slurry described in step (1) to make the ammonia concentration of the system 4 g / L. Then add the nickel cobalt manganese metal sulfate solution described in step (1) (addition rate of 30 L / h), sodium hydroxide solution, ammonia water and hexadecyltrimethylammonium bromide solution in parallel. Keep stirring and nitrogen atmosphere, control the reaction temperature at 60℃, maintain pH at 10.8, maintain the ammonia concentration in the system at 4 g / L, turn on the concentrator to continuously concentrate, and carry out the growth reaction for 40 h.

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

[0077] (3) Morphology guidance: The growth reaction continues until the solid content of the system reaches 850 g / L. The reaction parameters of the growth stage are maintained (no need to add hexadecyltrimethylammonium bromide solution). The nickel cobalt manganese metal sulfate solution, sodium hydroxide solution, ammonia water and urea solution described in step (1) are added in parallel. At the same time, the concentration is carried out and the morphology guidance reaction is carried out for 60 h. In the morphology guidance reaction system, the concentration of urea is 0.05 g / L. Finally, after centrifugation, washing, drying and sieving, the ternary precursor is obtained. The chemical formula of the ternary precursor is Ni 0.6 Co 0.2 Mn 0.2 (OH)2.

[0078] Example 3

[0079] This embodiment provides a method for preparing a ternary precursor, the method comprising the following steps:

[0080] (1) Nucleus preparation: Using the reverse addition method, pure water and 10 mol / L sodium hydroxide solution were added to the reactor to obtain a first precipitant solution with a pH of 12.8. Stirring was started, the reaction temperature was controlled at 50℃, and nitrogen gas was continuously introduced into the reactor 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 1 hour to reduce the pH of the system to 10.5 and obtain the nucleus slurry.

[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 influent rate of the nickel-cobalt-manganese metal sulfate solution is 30 L / h.

[0082] (2) Growth: Add ammonia water to the crystal nucleus slurry described in step (1) to make the ammonia concentration of the system 4 g / L. Then add the nickel cobalt manganese metal sulfate solution described in step (1) in parallel (addition rate of 30 L / h), sodium hydroxide solution and ammonia water. Keep stirring and nitrogen atmosphere, control the reaction temperature at 60℃, maintain pH at 10.8, maintain the ammonia concentration in the system at 4 g / L, turn on the concentrator to continuously concentrate, and carry out the growth reaction for 38 h.

[0083] (3) Morphology guidance: The growth reaction continues until the solid content of the system reaches 800 g / L. The reaction parameters of the growth stage are maintained, and the nickel-cobalt-manganese metal sulfate solution, sodium hydroxide solution, ammonia water and urea solution described in step (1) are added in parallel. At the same time, the mixture is concentrated and the morphology guidance reaction is carried out for 55 h. In the morphology guidance reaction system, the concentration of urea is 0.05 g / L. Finally, after centrifugation, washing, drying and sieving, the ternary precursor is obtained. The chemical formula of the ternary precursor is Ni 0.6 Co 0.1 Mn 0.3 (OH)2.

[0084] Example 4

[0085] This embodiment provides a method for preparing a ternary precursor, the method comprising the following steps:

[0086] (1) Nucleus preparation: Using the reverse addition method, pure water and 10 mol / L sodium hydroxide solution were added to the reactor to obtain a first precipitant solution with a pH of 12.4. Stirring was started, the reaction temperature was controlled at 50℃, and nitrogen gas was continuously introduced into the reactor 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 to reduce the pH of the system to 10.5 and obtain the nucleus slurry.

[0087] 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 influent rate of the nickel-cobalt-manganese metal sulfate solution is 30 L / h.

[0088] (2) Growth: Add ammonia water to the crystal nucleus slurry described in step (1) to make the ammonia concentration of the system 3.5 g / L. Then add the nickel cobalt manganese metal sulfate solution described in step (1) (addition rate of 30 L / h), sodium hydroxide solution, ammonia water and hexadecyltrimethylammonium bromide solution in parallel. Keep stirring and nitrogen atmosphere, control the reaction temperature at 65℃, maintain pH at 10.6, maintain the ammonia concentration in the system at 3.5 g / L, turn on the concentrator to continuously concentrate, and carry out the growth reaction for 38 h.

[0089] In the growth reaction system, the concentration of hexadecyltrimethylammonium bromide is 0.1 g / L;

[0090] (3) Morphology guidance: The growth reaction continues until the solid content of the system reaches 800 g / L. The reaction parameters of the growth stage are maintained (no need to add hexadecyltrimethylammonium bromide solution). The nickel cobalt manganese metal sulfate solution, sodium hydroxide solution, ammonia water and urea solution described in step (1) are added in parallel. At the same time, the concentration is carried out and the morphology guidance reaction is carried out for 55 h. In the morphology guidance reaction system, the concentration of urea is 0.1 g / L. Finally, after centrifugation, washing, drying and sieving, the ternary precursor is obtained. The chemical formula of the ternary precursor is Ni 0.6 Co 0.1 Mn 0.3 (OH)2.

[0091] Example 5

[0092] This embodiment provides a method for preparing a ternary precursor, the method comprising the following steps:

[0093] (1) Nucleus preparation: Using the reverse addition method, pure water and 10 mol / L sodium hydroxide solution were added to the reactor to obtain a first precipitant solution with a pH of 12.4. Stirring was started, the reaction temperature was controlled at 50℃, and nitrogen gas was continuously introduced into the reactor 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 to reduce the pH of the system to 10.5 and obtain the nucleus slurry.

[0094] In the nickel-cobalt-manganese metal sulfate solution, the molar ratio of nickel ions, cobalt ions, and manganese ions is 0.7:0.1:0.2, and the influent rate of the nickel-cobalt-manganese metal sulfate solution is 30 L / h.

[0095] (2) Growth: Add ammonia water to the crystal nucleus slurry described in step (1) to make the ammonia concentration of the system 3.5 g / L. Then add the nickel cobalt manganese metal sulfate solution described in step (1) in parallel flow (addition rate of 30 L / h), sodium hydroxide solution, ammonia water and polyethylene glycol solution. Keep stirring and nitrogen atmosphere, control the reaction temperature at 65℃, maintain pH at 10.6, maintain the ammonia concentration in the system at 3.5 g / L, turn on the concentrator to continuously concentrate and carry out the growth reaction.

[0096] In the growth reaction system, the concentration of polyethylene glycol is 0.2 g / L;

[0097] (3) Morphology guidance: The growth reaction continues until the solid content of the system reaches 850 g / L. The reaction parameters of the growth stage are maintained (no polyethylene glycol solution is needed). The nickel cobalt manganese metal sulfate solution, sodium hydroxide solution, ammonia and urea solution described in step (1) are added in parallel. The mixture is concentrated and the morphology guidance reaction is carried out for 62 h. The concentration of urea in the morphology guidance reaction system is 0.2 g / L. Finally, after centrifugation, washing, drying and sieving, the ternary precursor is obtained. The chemical formula of the ternary precursor is Ni 0.7 Co 0.1 Mn 0.2 (OH)2.

[0098] Example 6

[0099] This embodiment provides a method for preparing a ternary precursor, the method comprising the following steps:

[0100] (1) Nucleus preparation: Using the reverse addition method, pure water and 10 mol / L sodium hydroxide solution were added to the reactor to obtain a first precipitant solution with a pH of 12.4. Stirring was started, the reaction temperature was controlled at 50℃, and nitrogen gas was continuously introduced into the reactor 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 to reduce the pH of the system to 10.5 and obtain the nucleus slurry.

[0101] In the nickel-cobalt-manganese metal sulfate solution, the molar ratio of nickel ions, cobalt ions, and manganese ions is 0.7:0.1:0.2, and the influent rate of the nickel-cobalt-manganese metal sulfate solution is 30 L / h.

[0102] (2) Growth: Add ammonia water to the crystal nucleus slurry described in step (1) to make the ammonia concentration of the system 3.5 g / L, and then add the nickel cobalt manganese metal sulfate solution described in step (1) (addition rate of 30 L / h), sodium hydroxide solution, ammonia water and polyethylene glycol solution in parallel. Keep stirring and nitrogen atmosphere, control the reaction temperature at 65℃, maintain pH at 10.6, maintain the ammonia concentration in the system at 3.5 g / L, turn on the concentrator to continuously concentrate, and carry out the growth reaction for 40 h;

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

[0104] (3) Morphology guidance: The growth reaction continues until the solid content of the system reaches 850 g / L. The reaction parameters of the growth stage are maintained (no polyethylene glycol solution is needed). The nickel cobalt manganese metal sulfate solution, sodium hydroxide solution and ammonia water described in step (1) are added in parallel. The mixture is concentrated and the morphology guidance reaction is carried out for 62 h. Finally, after centrifugation, washing, drying and sieving, the ternary precursor is obtained. The chemical formula of the ternary precursor is Ni 0.7 Co 0.1 Mn 0.2 (OH)2.

[0105] Example 7

[0106] This embodiment provides a method for preparing a ternary precursor. Except for step (3), which involves growth reaction until the solid content of the system reaches 700 g / L, and then morphology guidance in step (3), the preparation method is the same as in Example 1.

[0107] Example 8

[0108] This embodiment provides a method for preparing a ternary precursor. The preparation method is the same as in Example 1 except that hexadecyltrimethylammonium bromide solution is not added in step (2).

[0109] Example 9

[0110] This embodiment provides a method for preparing a ternary precursor. Except for the concentration of hexadecyltrimethylammonium bromide in the growth reaction system described in step (2) being 1 g / L, the preparation method is the same as in Example 1.

[0111] Example 10

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

[0113] Example 11

[0114] This embodiment provides a method for preparing a ternary precursor. Except for the concentration of urea in the morphology-guided reaction system described in step (3) being 1 g / L, the preparation method is the same as in Example 1.

[0115] Example 12

[0116] This embodiment provides a method for preparing a ternary precursor. The preparation method is the same as in Example 1 except that hexadecyltrimethylammonium bromide solution is not added in step (2) and urea solution is not added in step (3).

[0117] Comparative Example 1

[0118] This comparative example provides a method for preparing a ternary precursor. Except for step (1), which uses the additive method to prepare the nucleus, i.e., passing the first precipitant solution into the nickel cobalt manganese sulfate solution, the preparation method is the same as in Example 1.

[0119] The SEM image of the crystal nucleus obtained in step (1) of this comparative example is shown below. Figure 5 As shown, by Figure 5 As can be seen, the primary particles did not form granules but rather lamellar structures, making it difficult for them to subsequently grow into thick hexagonal plates; the SEM image of the ternary precursor obtained in this comparative example is shown below. Figure 6 As shown, by Figure 6 It can be seen that the primary particles of the obtained ternary precursor are lamellar, with some primary particles being slightly regular hexagonal plates, but compared to... Figure 3 The thickness of the hexagonal sheet in the middle is significantly thinner.

[0120] Comparative Example 2

[0121] This comparative example provides a method for preparing a ternary precursor. Except for step (3), which involves growth reaction until the solid content of the system reaches 600 g / L, and then morphology guidance in step (3), the preparation method is the same as in Example 1.

[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 embodiments and comparative examples were tested. Specifically, the particle size D50 of the ternary precursors was measured using a Malvern particle size analyzer, the BET of the ternary precursors was measured using a specific surface area analyzer, and the TD of the ternary precursors was measured using a tap density meter. The SEM images of the ternary precursors were analyzed using Nano Measurer software to measure the length and width of primary particles and calculate the aspect ratio of primary particles.

[0123] The ternary precursors obtained in the above examples and comparative examples were mixed with lithium carbonate (the molar ratio of total metal ions in the ternary precursor to lithium ions in lithium carbonate was 1:1.05) and sintered at 900°C for 15 h to obtain the cathode material. The SEM images of the cathode material were analyzed using IPWIN software to obtain the roundness of the cathode particles, and the compaction density of the cathode material at 5T was tested using a compaction density meter.

[0124] After the positive electrode material prepared above was fabricated into a battery, it was subjected to 100 cycles at 1C and 2.7~4.3V to obtain the capacity retention rate after 100 cycles. The battery fabrication steps included: weighing positive electrode material, acetylene black, and PVDF in a mass ratio of 8:1:1, mixing them evenly with N-methylpyrrolidone as a solvent to prepare a slurry, coating the slurry onto aluminum foil, and vacuum drying. Then, using lithium metal sheet as the negative electrode, polypropylene membrane as the separator, and LiPF6-EC / DMC as the electrolyte, the battery was assembled in a glove box.

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

[0126] Table 1

[0127]

[0128] As can be seen from Table 1 above:

[0129] As can be seen from Examples 1-6 and Comparative Example 1, the present invention uses an inverse addition method in the preparation of crystal nuclei, which is beneficial for forming granular primary particles and preferentially growing towards the {101} plane. This reduces the BET of the ternary precursor and the aspect ratio of the primary particles, improves the TD of the ternary precursor, improves the roundness and compaction density of the cathode material, and improves the capacity retention of the battery. As can be seen from Examples 1-6, Example 7 and Comparative Example 2, the present invention requires the growth reaction to reach a solid content of more than 700 g / L before performing the morphology-guided reaction. Comparative Example 2 performed the morphology-guided reaction at a low solid content, and the primary particles were only slightly thick hexagonal plates with an aspect ratio greater than 2, resulting in the deterioration of the physical properties of the ternary precursor and cathode material, and a decrease in the cycle performance of the battery. As can be seen from Examples 1, 8, 10 and 12, adding a first crystal plane guide agent during the growth reaction in step (2) and adding a second crystal plane guide agent during the morphology guidance reaction in step (2) can suppress the growth of the {001} plane and promote the exposure of the {101} plane, thereby helping to reduce the aspect ratio of the primary particles of the ternary precursor. It is preferable to add the crystal plane guide agent at least in one of the growth stage and the morphology guidance stage; otherwise, the physical properties of the ternary precursor and the cathode material will be greatly degraded, affecting the cycle performance of the battery. As shown in Examples 1, 9 and 11, when the amount of the first and second crystal plane guide agents added is too much, it will increase the cost and the improvement effect will not be obvious.

[0130] 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 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 nucleation 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.

3. The preparation method according to claim 1, characterized in that, The temperature of the nucleation reaction in step (1) is 40℃~60℃.

4. The preparation method according to claim 1, characterized in that, The time for passing the nickel-cobalt-manganese metal source solution into the first precipitant solution in step (1) is 0.5h to 3h.

5. The preparation method according to claim 1, characterized in that, After the nucleation reaction in step (1) is completed, the pH of the system drops to 10-11.

6. The preparation method according to claim 1, 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.

7. The preparation method according to claim 1, characterized in that, 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.

8. The preparation method according to claim 1, characterized in that, A first crystal plane guiding agent was also added during the growth reaction described in step (2).

9. The preparation method according to claim 8, characterized in that, 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.

10. The preparation method according to claim 9, characterized in that, In the growth reaction system, the concentration of the first crystal plane guiding agent is 0.05 g / L to 0.2 g / L.

11. The preparation method according to claim 8, characterized in that, The first crystal plane directing agent includes any one or a combination of at least two of octadecylphosphonic acid, dodecylphosphonic acid, vinylphosphonic acid, sodium dodecylbenzenesulfonate, hexadecyltrimethylammonium bromide, polyethylene glycol, or polyvinylpyrrolidone.

12. The preparation method according to claim 1, characterized in that, In step (2), the concentration of the complexing agent in the system is 2 g / L to 6 g / L when the complexing agent solution is added.

13. The preparation method according to claim 1, characterized in that, The growth reaction in step (2) is carried out at a temperature of 50℃~80℃ and a pH of 10~11.

14. The preparation method according to claim 1, characterized in that, In the growth reaction system described in step (2), the concentration of the complexing agent is 2 g / L to 6 g / L.

15. The preparation method according to claim 1, characterized in that, In step (2), the growth reaction process is continuously concentrated.

16. The preparation method according to claim 1, characterized in that, In step (2), the concentration of the second precipitant solution is 5 mol / L to 10 mol / L.

17. The preparation method according to claim 1, characterized in that, In step (2), when the growth reaction reaches a solid content of 700 g / L to 1000 g / L, a morphology-guided reaction is carried out.

18. The preparation method according to claim 1, characterized in that, The morphology-guided reaction in step (3) takes 40-80 hours.

19. The preparation method according to claim 1, characterized in that, A second crystal plane guiding agent was also added during the morphology-guided reaction described in step (3).

20. The preparation method according to claim 19, characterized in that, In the morphology-guided reaction system described in step (3), the concentration of the second crystal plane guide agent is 0 g / L to 1 g / L.

21. The preparation method according to claim 20, characterized in that, In the morphology-guided reaction system, the concentration of the second crystal plane directing agent is 0.05 g / L to 0.2 g / L.

22. The preparation method according to claim 19, characterized in that, The second crystal plane directing agent includes urea and / or ethylenediamine.

23. The preparation method according to claim 1, characterized in that, The width of the primary particles of the ternary precursor in step (3) is above 350 nm.

24. The preparation method according to claim 23, characterized in that, The width of the primary particles of the ternary precursor is 350 nm to 700 nm.

25. The preparation method according to claim 24, characterized in that, The width of the primary particles of the ternary precursor is 400nm~500nm.

26. The preparation method according to claim 1, characterized in that, The aspect ratio of the primary particles of the ternary precursor in step (3) is ≤2.

27. The preparation method according to claim 26, characterized in that, The aspect ratio of the primary particles of the ternary precursor is 1.5 to 2.

0.

28. The preparation method according to claim 1, characterized in that, The particle size D50 of the ternary precursor in step (3) is 2.5 μm to 8 μm.

29. The preparation method according to claim 28, characterized in that, The particle size D50 of the ternary precursor is 3.5 μm to 4.0 μm.

30. The preparation method according to claim 1, characterized in that, The BET of the ternary precursor in step (3) is ≤5m 2 / g.

31. The preparation method according to claim 30, characterized in that, The BET of the ternary precursor is 3m. 2 / g~5m 2 / g.

32. The preparation method according to claim 1, characterized in that, The TD of the ternary precursor in step (3) is ≥1.7 g / cm³. 3 .

33. The preparation method according to claim 32, characterized in that, The TD of the ternary precursor is 1.7 g / cm³. 3 ~2.0g / cm 3 .

34. A ternary precursor, characterized in that, The ternary precursor is prepared by the preparation method according to any one of claims 1-33.

35. A positive electrode material, characterized in that, The precursor for preparing the cathode material includes the ternary precursor as described in claim 34.

36. A battery, characterized in that, The battery includes the positive electrode material as described in claim 35.

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