A ternary precursor of primary particles vertically stacked and a preparation method and application thereof

Abstract

This invention discloses a ternary precursor with vertically stacked particles in a single step, its preparation method, and its application, belonging to the field of battery material technology. The preparation of the ternary precursor includes: Step 1: Adding a first mixed metal salt solution, a precipitant, and a complexing agent to a base solution, reacting for 0.5h~20h to obtain crystal nuclei; Step 2: Increasing the rotation speed and ammonia concentration, while maintaining other conditions as in Step 1, continuing the reaction for 4h~12h to obtain crystals; Step 3: Replacing the first mixed metal salt solution with a second mixed metal salt solution, while maintaining other conditions as in Step 2, continuing the reaction until particles of a predetermined target particle size are obtained. This method is simple, easy to operate, and can obtain precursor materials with vertically stacked particles in a single step. This precursor helps shorten the lithium-ion transport path, improves the rate performance of the battery, and has good pressure resistance, which can reduce microcracks caused by mechanical forces and improve the battery's lifespan.

Description

Technical Field

[0001] This invention relates to the field of battery materials technology, and more specifically, to a ternary precursor with vertically stacked primary particles, its preparation method, and its application. Background Technology

[0002] Ternary precursors are crucial compounds in the manufacture of cathode materials for lithium-ion batteries, directly impacting the battery's energy density, rate performance, cycle life, and safety. In terms of elemental roles, nickel increases energy density, cobalt enhances material stability, while manganese helps reduce costs and improve safety. The industrialization of precursors primarily involves adjusting the nickel-cobalt-manganese ratio to obtain nickel-cobalt-manganese ternary cathode materials with varying properties to meet diverse application requirements.

[0003] Primary particles refer to individual crystals formed during precursor synthesis and are crucial to the electrical performance of the final electrode material. The packing pattern and morphology of primary particles affect the ion channels of the electrode material. For electrode materials of the same size, shorter ion channels are more conducive to the diffusion rate of lithium ions within the electrode material, thus improving the battery's rate performance. Furthermore, the mechanical strength of primary particles affects the structural stability of the electrode material during cycling. Higher mechanical strength can reduce microcracks generated in the electrode material during charging and discharging, extending battery life.

[0004] Currently, there is no ternary precursor that can simultaneously shorten the lithium-ion transport path and improve mechanical strength.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a ternary precursor with vertically stacked particles in a single step, its preparation method and application, so as to solve or improve the above-mentioned technical problems.

[0007] This invention can be implemented as follows:

[0008] In a first aspect, the present invention provides a method for preparing a ternary precursor with a single-stage vertically stacked particle structure, wherein the chemical formula of the ternary precursor is Ni. x Co y Mn 1-x-y (OH)2, where 0.5≤x≤0.8, 0.02≤y≤0.35, and x+y<1;

[0009] The preparation of ternary precursors includes:

[0010] Step 1: Add the first mixed metal salt solution, precipitant, and complexing agent to the base solution, and react for 0.5 h to 20 h to obtain crystal nuclei;

[0011] The base solution consists of water, ammonia, and liquid alkali; the mass concentration of the liquid alkali is 10%~40%, and the pH value of the base solution is 10.5~12.5; the ammonia concentration in the base solution is 0.5g / L~6g / L, and the mass concentration of the ammonia solution is 10%~30%; the temperature of the base solution is 35℃~80℃; the base solution is stirred at a speed of 100rpm~500rpm; and a protective gas is continuously introduced into the base solution.

[0012] The metal salts in the first mixed metal salt solution include a first nickel salt, a first cobalt salt, and a first manganese salt. The molar ratio of Ni in the first nickel salt, Co in the first cobalt salt, and Mn in the first manganese salt is x:y:(1-xy). The total molar concentration of the metals in the first mixed metal salt solution is 1 mol / L to 1.5 mol / L.

[0013] The precipitant is a liquid alkali with a mass concentration of 10% to 40%, and the complexing agent is ammonia water with a mass concentration of 10% to 30%.

[0014] The flow rate of the first mixed metal salt solution is 1 L / h to 4 L / h;

[0015] Step 2: Increase the rotation speed and ammonia concentration, while keeping the other conditions the same as in Step 1, and continue the reaction for 4 to 12 hours to obtain crystals;

[0016] Step 3: Replace the first mixed metal salt solution with the second mixed metal salt solution, keeping the other conditions the same as in Step 2, and continue the reaction until particles of the preset target particle size are obtained;

[0017] The metal salts in the second mixed metal salt solution include a second nickel salt, a second cobalt salt, and a second manganese salt. The molar ratio of Ni in the second nickel salt, Co in the second cobalt salt, and Mn in the second manganese salt is x:y:(1-xy). The total molar concentration of metals in the second mixed metal salt solution is higher than that in the first mixed metal salt solution.

[0018] In an optional implementation, the D of the crystal nucleus 50 The size is 1μm to 2μm.

[0019] In an optional implementation, in step 2, the rotation speed is increased to 1.5 to 3 times that of the rotation speed in step 1, and the ammonia concentration is increased to 3 to 5 times that of the ammonia concentration in step 1.

[0020] In an optional embodiment, the total metal molar concentration in the second mixed metal salt solution is 1.1 to 1.3 times the total metal molar concentration in the first mixed metal salt solution.

[0021] In optional embodiments, the method further includes: aging, pulping, washing, drying, sieving, and demagnetizing particles of a preset target particle size.

[0022] In an optional embodiment, slurrying is carried out using an aqueous solution of NaOH with a concentration of 0.1 mol / L to 3 mol / L.

[0023] Secondly, the present invention provides a ternary precursor, which is prepared by any of the preparation methods described in the foregoing embodiments.

[0024] In an optional implementation, the primary particles of the ternary precursor are in the shape of laths, and the primary particles are stacked vertically, with the vertical direction being the length direction of the laths.

[0025] Thirdly, the present invention provides a ternary cathode material, wherein the precursor of the ternary cathode material is the ternary precursor of the aforementioned embodiments.

[0026] Fourthly, the present invention provides a battery in which the positive electrode material is the ternary positive electrode material of the aforementioned embodiments.

[0027] The beneficial effects of this invention include:

[0028] In the preparation method of the ternary precursor provided by this invention, by increasing the rotation speed and ammonia concentration in step 2, the crystal nucleus obtained in step 1 is used as the growth point of the primary particles, and they grow in an orderly vertical stacking outward from the crystal nucleus. After a period of reaction, crystals appear on the surface of the crystal nucleus. The vertical stacking of the basic crystals is achieved through the orientation growth of the crystals, thereby obtaining a vertically stacked growth template. Then, in step 3, the concentration of the mixed metal salt solution is increased, thereby increasing the growth rate and growth kinetics of the material, so that the material obtained from the precipitation reaction grows rapidly vertically along the growth template. This preparation method is simple and easy to operate, and can obtain precursor material with effective vertical stacking of primary particles. This precursor can not only optimize the lithium-ion channel, shorten the lithium-ion transport path, and improve the rate performance of the battery, but also has good pressure resistance, which can reduce microcracks caused by mechanical force and improve the battery's service life. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 The image shows the SEM image of the crystal nucleus obtained in step 1 of Example 1.

[0031] Figure 2 This is an SEM image of the crystals obtained in step 2 of Example 1;

[0032] Figure 3 The image shows the SEM image of the ternary precursor obtained in step 3 of Example 1.

[0033] Figure 4 SEM image of the ternary precursor prepared in Comparative Example 1;

[0034] Figure 5 The image shows the SEM image of the ternary precursor prepared in Comparative Example 2. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0036] The following is a detailed description of the ternary precursor with vertically stacked particles provided by the present invention, its preparation method, and its application.

[0037] This invention provides a method for preparing a ternary precursor with vertically stacked particles in a single step. The chemical formula of the ternary precursor is Ni. x Co y Mn 1-x-y (OH)2, where 0.5≤x≤0.8, 0.02≤y≤0.35, and x+y<1.

[0038] The preparation of this ternary precursor includes:

[0039] Step 1: Add the first mixed metal salt solution, precipitant, and complexing agent to the base solution, and react for 0.5h~20h to obtain crystal nuclei.

[0040] The base solution consists of water, ammonia, and liquid alkali.

[0041] The mass concentration of ammonia water can be 10% to 30%, such as 10%, 15%, 20%, 25%, or 30%, or other values ​​within the range of 10% to 30%. The addition of ammonia water is mainly used to control the ammonia concentration in the base solution. For example, the ammonia concentration in the base solution can be 0.5 g / L to 6 g / L, such as 0.5 g / L, 1 g / L, 1.5 g / L, 2 g / L, 2.5 g / L, 3 g / L, 3.5 g / L, 4 g / L, 4.5 g / L, 5 g / L, 5.5 g / L, or 6 g / L, or other values ​​within the range of 0.5 g / L to 6 g / L.

[0042] The mass concentration of the liquid alkali can be 10% to 40%, such as 10%, 15%, 20%, 25%, 30%, 35%, or 40%, or other values ​​within the range of 10% to 40%. The addition of liquid alkali is mainly used to control the pH value in the base solution. For example, the pH value of the base solution can be 10.5 to 12.5, such as 10.5, 10.8, 11, 11.2, 11.5, 11.8, 12, 12.2, or 12.5, or other values ​​within the range of 10.5 to 12.5.

[0043] The temperature of the base solution can be set between 35℃ and 80℃, such as 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, or 80℃, or other values ​​within the range of 35℃ to 80℃. The above temperatures of the base solution can be achieved by heating a mixture of water, ammonia, and liquid alkali.

[0044] The base liquid is in a stirring state and the stirring speed is 100rpm~500rpm. For example, the stirring speed can be 100rpm, 150rpm, 200rpm, 250rpm, 300rpm, 350rpm, 400rpm, 450rpm or 500rpm, or other values ​​within the range of 100rpm~500rpm.

[0045] A protective gas can be continuously introduced into the bottom fluid.

[0046] The metal salts in the aforementioned first mixed metal salt solution include a first nickel salt, a first cobalt salt, and a first manganese salt. The molar ratio of Ni in the first nickel salt, Co in the first cobalt salt, and Mn in the first manganese salt is x:y:(1-xy), which corresponds to the chemical formula of the ternary precursor. The first nickel salt, first cobalt salt, and first manganese salt can, exemplarily, be in sulfate form, such as nickel sulfate, cobalt sulfate, and manganese sulfate; alternatively, they can also be in nitrate and / or chloride form.

[0047] The total metal molar concentration in the first mixed metal salt solution is 1 mol / L to 1.5 mol / L, such as 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, or 1.5 mol / L, or other values ​​within the range of 1 mol / L to 1.5 mol / L.

[0048] The precipitant is a liquid alkali with a mass concentration of 10% to 40%, which can be the same as the liquid alkali added to the base solution.

[0049] The complexing agent is ammonia water with a mass concentration of 10% to 30% (such as 10%, 15%, 20%, 25% or 30%), which can be the same as the ammonia water added to the base solution.

[0050] The flow rate of the first mixed metal salt solution can be from 1 L / h to 4 L / h, such as 1 L / h, 1.5 L / h, 2 L / h, 2.5 L / h, 3 L / h, 3.5 L / h, or 4 L / h. The flow rate of the precipitant is adjusted to maintain a preset pH value, and the flow rate of the complexing agent is adjusted to maintain a preset ammonia value.

[0051] In some optional implementations, the reaction time of step 1 can be 0.5h, 1h, 2h, 5h, 8h, 10h, 12h, 15h, 18h or 20h, or other values ​​within the range of 0.5h to 20h.

[0052] In some alternative implementations, the D of the resulting crystal nucleus 50 It can be 1μm~2μm.

[0053] As mentioned above, step 1 can be understood as the nucleation period in the preparation process of the ternary precursor. The crystal nuclei obtained in this stage are flocculent and have no obvious crystal structure.

[0054] Step 2: Increase the rotation speed and ammonia concentration, while keeping the other conditions the same as in Step 1, and continue the reaction for 4 to 12 hours to obtain crystals.

[0055] In some optional implementations, the rotational speed in step 2 can be increased to 1.5 to 3 times that in step 1, such as 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9 times, 2.0 times, 2.1 times, 2.2 times, 2.3 times, 2.4 times, 2.5 times, 2.6 times, 2.7 times, 2.8 times, 2.9 times, or 3 times, or other values ​​within the range of 1.5 to 3 times.

[0056] Increasing the rotation speed can form primary particle flakes with a distinct crystalline structure. If the rotation speed is increased too little, it is not conducive to particle crystallization and the transformation from flocculent nuclei to primary particle nuclei is impossible; if the rotation speed is increased too much, it can easily lead to growth stagnation, thereby changing the morphology and structure of the primary particles.

[0057] In some optional embodiments, the ammonia concentration in step 2 can be increased to 3 to 5 times the ammonia concentration in step 1, such as 3 times, 3.2 times, 3.5 times, 3.8 times, 4 times, 4.2 times, 4.5 times, 4.8 times or 5 times, or other values ​​within the range of 3 to 5 times.

[0058] Increasing the ammonia concentration can induce oriented growth. If the ammonia concentration is increased too little, it will not be conducive to the alteration of primary particles, and vertical primary particles cannot be obtained; if the ammonia concentration is increased too much, it will easily lead to changes in the complexation capacity of the system, and the element ratio will deviate from the design value.

[0059] In some optional implementations, the reaction time in step 2 can be 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, 10h or 12h, or other values ​​within the range of 4h to 12h.

[0060] Continuing from the above, step 2 can be understood as the crystallization period in the preparation process of the ternary precursor. In this stage, the crystal nucleus obtained in step 1 is used as the growth point of the primary particles, and the particles are vertically and orderly stacked outward from the crystal nucleus. After a period of reaction, crystals appear on the surface of the crystal nucleus. The vertical stacking of the basic crystal is achieved through the orientation growth of the crystal, thereby obtaining the vertically stacked growth template.

[0061] Step 3: Replace the first mixed metal salt solution with the second mixed metal salt solution, keeping the other conditions the same as in Step 2, and continue the reaction until particles of the preset target particle size are obtained.

[0062] The metal salts in the second mixed metal salt solution include a second nickel salt, a second cobalt salt, and a second manganese salt. The molar ratio of Ni in the second nickel salt, Co in the second cobalt salt, and Mn in the second manganese salt is x:y:(1-xy). The total molar concentration of metals in the second mixed metal salt solution is higher than that in the first mixed metal salt solution.

[0063] This can be understood as follows: the molar ratio of Ni, Co, and Mn in the second mixed metal salt solution is the same as that in the first mixed metal salt solution, only the concentration of each metal salt is increased.

[0064] In some optional embodiments, the total metal molar concentration in the second mixed metal salt solution is 1.1 to 1.3 times the total metal molar concentration in the first mixed metal salt solution, such as 1.1 times, 1.15 times, 1.2 times, 1.25 times, or 1.3 times, or other values ​​within the range of 1.1 to 1.3.

[0065] Increasing the concentration of the mixed metal salt solution in this step can improve the growth rate and growth kinetics of the material, allowing the material obtained from the precipitation reaction to grow rapidly vertically along the growth template. If the concentration of the mixed metal salt solution is increased too little, the growth rate will be too slow, and some of the material obtained from the precipitation reaction may grow in other directions during this process. If the concentration of the mixed metal salt solution is increased too much, the concentration of the local reaction system may be too high, causing the material to nucleate separately at that location, making it difficult to grow uniformly.

[0066] As mentioned above, step 3 can be understood as the growth period in the preparation process of ternary precursors. During this stage, the material achieves rapid growth in the vertical direction, with virtually no lateral growth.

[0067] Furthermore, the obtained particles of the preset target particle size can be aged, pulped, washed, dried, sieved, and demagnetized.

[0068] Aging can be carried out in an aging kettle for 8 to 12 hours. After aging, filter the cake and add it to a 0.1 mol / L to 3 mol / L NaOH aqueous solution for slurry preparation. After slurry preparation, filter the cake again and wash it until the pH of the filtrate is less than 9. Then, dry, sieve, and demagnetize the washed cake.

[0069] Accordingly, the present invention also provides a ternary precursor, which is prepared by the above-described preparation method.

[0070] The primary particles of this ternary precursor are lath-shaped and stacked vertically.

[0071] The aforementioned "vertical stacking" can be understood as: growing vertically outward from the surface of the crystal nucleus, that is, the vertical direction is the length direction in the lath-like structure. In other words, the length direction of the primary particles does not extend circumferentially or laterally along the surface of the crystal nucleus, but rather extends vertically outward from the surface of the crystal nucleus in a radial pattern.

[0072] The ternary precursors with the above characteristics have shorter ion channels after sintering, which helps lithium ion insertion and extraction and can improve the rate performance of ternary cathode materials. In addition, the ternary precursors with the above characteristics also have better pressure resistance, which can avoid or reduce microcracks caused by mechanical force, which is beneficial to improving the cycle performance of the battery and extending the battery's service life.

[0073] In some alternative implementations, the size of the ternary precursor does not exceed 5 μm.

[0074] In addition, the present invention also provides a ternary cathode material, wherein the precursor of the ternary cathode material is the ternary precursor of the aforementioned embodiments.

[0075] Furthermore, the present invention also provides a battery in which the positive electrode material is the aforementioned ternary positive electrode material.

[0076] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0077] Example 1

[0078] This embodiment provides a ternary precursor, the preparation method of which is as follows:

[0079] Step 1: Add the first mixed metal salt solution, precipitant, and complexing agent to the base solution, react for 8 hours, and obtain crystal nuclei (e.g., Figure 1 (As shown).

[0080] The base solution consists of water, ammonia, and liquid alkali.

[0081] The ammonia concentration is 15%, and the ammonia concentration in the base solution is 4 g / L. The concentration of the liquid alkali is 22 wt%, and the pH value of the base solution can be 11.9. The temperature of the base solution is 50℃, and the base solution is stirred at a speed of 300 rpm. Nitrogen gas is continuously introduced into the base solution.

[0082] The metal salts in the first mixed metal salt solution are nickel sulfate, cobalt sulfate, and manganese sulfate, with a molar ratio of Ni in nickel sulfate, Co in cobalt sulfate, and Mn in manganese sulfate of 0.7:0.1:0.2. The total molar concentration of the metals in the first mixed metal salt solution is 1.1 mol / L.

[0083] The precipitant is a 22wt% liquid alkali, which is the same liquid alkali added to the base solution.

[0084] The complexing agent is ammonia solution with a mass concentration of 15%, which is the same ammonia solution added to the base solution.

[0085] The flow rate of the first mixed metal salt solution was 2 L / h, the flow rate of the precipitant was adjusted to maintain a pH of 11.9, and the flow rate of the complexing agent was adjusted to maintain an ammonia concentration of 4 g / L.

[0086] The D of the obtained crystal nucleus 50 It is 1.5μm.

[0087] Step 2: Increase the rotation speed to 500 rpm and the ammonia concentration to 16 g / L, keeping other conditions the same as in Step 1, and continue the reaction for 12 hours. The disordered nuclei on the crystal surface will grow into regular crystals (such as...). Figure 2 As shown in the figure, the particles are stacked vertically.

[0088] Step 3: Replace the first mixed metal salt solution with the second mixed metal salt solution, keeping all other conditions the same as in Step 2, and continue the reaction until the preset target particle size (D) is obtained. 50 Particles with a diameter of 3.5 μm (e.g., = 3.5 μm) Figure 3 (As shown). During this stage, the primary particles at each location continue to grow outwards, exhibiting a radial distribution.

[0089] The metal salts in the second mixed metal salt solution are nickel sulfate, cobalt sulfate, and manganese sulfate, with a molar ratio of Ni in nickel sulfate, Co in cobalt sulfate, and Mn in manganese sulfate of 0.7:0.1:0.2. The total molar concentration of the metals in the second mixed metal salt solution is 1.45 mol / L.

[0090] Step 4: Aging the obtained particles of the preset target particle size in an aging kettle for 10 hours. After aging, filter the mixture, and add the filter cake to a 2 mol / L NaOH aqueous solution for slurrying. After slurrying, filter the mixture again, and wash the filtered filter cake until the pH of the filtrate is less than 9. Then, dry, sieve, and demagnetize the washed filter cake.

[0091] Example 2

[0092] This embodiment provides a ternary precursor, the preparation method of which is as follows:

[0093] Step 1: Add the first mixed metal salt solution, precipitant, and complexing agent to the base solution, react for 0.5 h, and obtain crystal nuclei.

[0094] The base solution consists of water, ammonia, and liquid alkali.

[0095] The ammonia concentration is 10%, and the ammonia concentration in the base solution can be 0.5 g / L. The concentration of the liquid alkali is 20 wt%, and the pH value of the base solution can be 10.5. The temperature of the base solution is 35℃, and the base solution is stirred at a speed of 100 rpm. Nitrogen gas is continuously introduced into the base solution.

[0096] The metal salts in the first mixed metal salt solution are nickel sulfate, cobalt sulfate, and manganese sulfate, with a molar ratio of Ni in nickel sulfate, Co in cobalt sulfate, and Mn in manganese sulfate of 0.7:0.1:0.2. The total molar concentration of the metals in the first mixed metal salt solution is 1 mol / L.

[0097] The precipitant is a 20wt% liquid alkali, which is the same liquid alkali added to the base solution.

[0098] The complexing agent is ammonia solution with a mass concentration of 10%, which is the same ammonia solution added to the base solution.

[0099] The flow rate of the first mixed metal salt solution is 1 L / h, the flow rate of the precipitant is adjusted to maintain a pH of 11.9, and the flow rate of the complexing agent is adjusted to maintain a preset ammonia value.

[0100] The D of the obtained crystal nucleus 50 It is 1.1 μm.

[0101] Step 2: Increase the rotation speed to 300 rpm and the ammonia concentration to 2.5 g / L. Keep the other conditions the same as in Step 1 and continue the reaction for 10 h. The disordered crystal nuclei on the surface of the crystal nuclei grow into regular crystals, and the primary particles are vertically stacked.

[0102] Step 3: Replace the first mixed metal salt solution with the second mixed metal salt solution, keeping all other conditions the same as in Step 2, and continue the reaction until the preset target particle size (D) is obtained. 50Particles with a diameter of 3.5 μm (approximately 3.5 μm) are observed. During this stage, primary particles at each location continue to grow outwards, exhibiting a radial distribution.

[0103] The metal salts in the second mixed metal salt solution are nickel sulfate, cobalt sulfate, and manganese sulfate, with a molar ratio of Ni in nickel sulfate, Co in cobalt sulfate, and Mn in manganese sulfate of 0.7:0.1:0.2. The total molar concentration of the metals in the second mixed metal salt solution is 1.1 mol / L.

[0104] Step 4: Aging the obtained particles of the preset target particle size in an aging kettle for 10 hours. After aging, filter the mixture, and add the filter cake to a 0.1 mol / L NaOH aqueous solution for slurry formation. After slurry formation, filter the mixture again, and wash the filtered filter cake until the pH of the filtrate is less than 9. Then, dry, sieve, and demagnetize the washed filter cake.

[0105] Example 3

[0106] This embodiment provides a ternary precursor, the preparation method of which is as follows:

[0107] Step 1: Add the first mixed metal salt solution, precipitant, and complexing agent to the base solution, react for 20 hours, and obtain crystal nuclei.

[0108] The base solution consists of water, ammonia, and liquid alkali.

[0109] The ammonia concentration is 30%, and the ammonia concentration in the base solution can be 6 g / L. The concentration of the liquid alkali is 25 wt%, and the pH value of the base solution can be 12.5. The temperature of the base solution is 80℃, and the base solution is stirred at a speed of 500 rpm. Nitrogen gas is continuously introduced into the base solution.

[0110] The metal salts in the first mixed metal salt solution are nickel sulfate, cobalt sulfate, and manganese sulfate, with a molar ratio of Ni in nickel sulfate, Co in cobalt sulfate, and Mn in manganese sulfate of 0.7:0.1:0.2. The total molar concentration of the metals in the first mixed metal salt solution is 1.5 mol / L.

[0111] The precipitant is a 25wt% liquid alkali, which is the same liquid alkali added to the base solution.

[0112] The complexing agent is ammonia solution with a mass concentration of 30%, which is the same ammonia solution added to the base solution.

[0113] The flow rate of the first mixed metal salt solution is 4 L / h, the flow rate of the precipitant is adjusted to maintain a pH of 11.9, and the flow rate of the complexing agent is adjusted to maintain a preset ammonia value.

[0114] The D of the obtained crystal nucleus 50 It is 1.7μm.

[0115] Step 2: Increase the rotation speed to 750 rpm and the ammonia concentration to 18 g / L. Keep the other conditions the same as in Step 1 and continue the reaction for 4 hours. The disordered crystal nuclei on the surface of the crystal nuclei grow into regular crystals, and the primary particles are vertically stacked.

[0116] Step 3: Replace the first mixed metal salt solution with the second mixed metal salt solution, keeping all other conditions the same as in Step 2, and continue the reaction until the preset target particle size (D) is obtained. 50 Particles with a diameter of 3.5 μm (approximately 3.5 μm) are observed. During this stage, primary particles at each location continue to grow outwards, exhibiting a radial distribution.

[0117] The metal salts in the second mixed metal salt solution are nickel sulfate, cobalt sulfate, and manganese sulfate, with a molar ratio of Ni in nickel sulfate, Co in cobalt sulfate, and Mn in manganese sulfate of 0.7:0.1:0.2. The total molar concentration of the metals in the second mixed metal salt solution is 1.95 mol / L.

[0118] Step 4: Aging the obtained particles of the preset target particle size in an aging kettle for 10 hours. After aging, filter the mixture, and add the filter cake to a 3 mol / L NaOH aqueous solution for slurrying. After slurrying, filter the mixture again, and wash the filtered filter cake until the pH of the filtrate is less than 9. Then, dry, sieve, and demagnetize the washed filter cake.

[0119] Comparative Example 1

[0120] The difference between this comparative example and Example 1 is that in step 2, the rotation speed is increased by 1.33 times while the ammonia concentration is maintained at 4 g / L as in step 1.

[0121] At the end of step 2 of the comparative example, most of the crystal nucleus surface is disordered crystals with a small amount of highly crystalline crystals, and the surface morphology varies significantly at different points. After entering the growth period, it is impossible to form a vertically stacked primary particle structure, and the primary particles on the surface vary greatly. Due to the influence of morphology, some physical and chemical indicators cannot meet the standards and are treated as waste.

[0122] The SEM images of the ternary precursors obtained in this comparative example are as follows: Figure 4 As shown.

[0123] Comparative Example 2

[0124] The difference between this comparative example and Example 1 is that the second mixed metal salt solution used in step 3 is the same as the first mixed metal salt solution used in steps 1 and 2, and no changes were made.

[0125] During the growth period of this comparative example, the grains grew slowly at one stage, and some grains grew laterally.

[0126] The SEM images of the ternary precursors obtained in this comparative example are as follows: Figure 5 As shown.

[0127] Comparative Example 3

[0128] The difference between this comparative example and Example 1 is that in step 2, the rotation speed is increased to 3.5 times that in step 1, while the ammonia concentration remains the same as in step 1.

[0129] Comparative Example 4

[0130] The difference between this comparative example and Example 1 is that in step 2, the rotation speed is kept the same as in step 1, and the ammonia concentration is increased to 2.5 times that in step 1.

[0131] Comparative Example 5

[0132] The difference between this comparative example and Example 1 is that in step 2, the rotation speed is kept the same as in step 1, and the ammonia concentration is increased to 5.5 times that in step 1.

[0133] Comparative Example 6

[0134] The difference between this comparative example and Example 1 is that in step 2, the rotation speed and ammonia concentration are kept the same as in step 1.

[0135] Comparative Example 7

[0136] The difference between this comparative example and Example 1 is that in step 3, the total molar concentration of the metal in the second mixed metal salt solution is twice that in the first mixed metal salt solution. The higher concentration of the second mixed salt resulted in the formation of fine powder during preparation, which was disposed of as waste.

[0137] Comparative Example 8

[0138] The difference between this comparative example and Example 1 is that in step 1, the ammonia concentration in the base solution is 8 g / L.

[0139] Comparative Example 9

[0140] The difference between this comparative example and Example 1 is that in step 1, the stirring speed is 600 rpm.

[0141] Comparative Example 10

[0142] The difference between this comparative example and Example 1 is that the total metal molar concentration in the first mixed metal salt solution is 2 mol / L.

[0143] Test case

[0144] The ternary precursors obtained in Examples 1-3 and Comparative Examples 1-10 were used to prepare ternary cathode materials and further assembled into coin cells. The performance of the resulting cells was compared, and the results are shown in Table 1.

[0145] The process of preparing ternary cathode material from ternary precursor is as follows: the precursor and lithium hydroxide are mixed evenly at a molar ratio of 1:1.05, sintered at 700℃, and then ground and pulverized to finally obtain the cathode material.

[0146] The process of assembling ternary cathode materials into coin cells is as follows: A slurry is prepared by mixing cathode material, conductive carbon, and polyvinylidene fluoride (PVDF) in a ratio of 90:5:5. This slurry is then used to fabricate the cathode sheet, and a lithium metal sheet is used as the anode material to assemble the coin cells. The coin cells are then subjected to electrochemical performance testing at 1C and 3.0V~4.35V.

[0147] Defect rate: The precursor material is coated on an aluminum foil sheet, and a 0.2 kg cylinder is used to perform a single roll test on the material surface. After roll test, the material sample is taken and the proportion of cracked or deformed particles is determined by scanning electron microscopy. This determines the compressive strength of the precursor material. The lower the defect rate, the better the compressive strength of the precursor material, and vice versa.

[0148] Table 1 Test Results

[0149]

[0150] As can be seen from Table 1, the ternary precursor prepared in the embodiments of the present invention is beneficial for further preparing batteries with both high rate performance and high voltage resistance.

[0151] In summary, the preparation method of the ternary precursor provided by this invention is simple and easy to operate, and can obtain precursor materials with vertically stacked particles in a single step. This ternary precursor not only optimizes lithium-ion channels and shortens lithium-ion transport paths, improving the rate performance of the battery, but also has good pressure resistance, reducing microcracks caused by mechanical forces and improving battery life.

[0152] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a ternary precursor with vertically stacked primary particles, characterized in that, The chemical formula of the ternary precursor is Ni x Co y Mn 1-x-y (OH)2, where 0.5≤x≤0.8, 0.02≤y≤0.35, and x+y<1; The preparation of the ternary precursor includes: Step 1: Add the first mixed metal salt solution, precipitant, and complexing agent to the base solution, and react for 0.5 h to 20 h to obtain crystal nuclei; The base solution comprises water, ammonia, and liquid alkali; the mass concentration of the liquid alkali is 10%~40%; the pH value of the base solution is 10.5~12.5; the ammonia concentration in the base solution is 0.5g / L~6g / L, and the mass concentration of the ammonia is 10%~30%; the temperature of the base solution is 35℃~80℃; the base solution is stirred at a speed of 100rpm~500rpm; and a protective gas is continuously introduced into the base solution. The metal salts in the first mixed metal salt solution include a first nickel salt, a first cobalt salt, and a first manganese salt. The molar ratio of Ni in the first nickel salt, Co in the first cobalt salt, and Mn in the first manganese salt is x:y:(1-xy). The total metal molar concentration in the first mixed metal salt solution is 1 mol / L to 1.5 mol / L. The precipitant is a liquid alkali with a mass concentration of 10% to 40%, and the complexing agent is ammonia water with a mass concentration of 10% to 30%. The flow rate of the first mixed metal salt solution is 1 L / h to 4 L / h; Step 2: Increase the rotation speed and ammonia concentration, while keeping the other conditions the same as in Step 1, and continue the reaction for 4 to 12 hours to obtain crystals; Step 3: Replace the first mixed metal salt solution with the second mixed metal salt solution, keeping the other conditions the same as in Step 2, and continue the reaction until particles of the preset target particle size are obtained; The metal salts in the second mixed metal salt solution include a second nickel salt, a second cobalt salt, and a second manganese salt. The molar ratio of Ni in the second nickel salt, Co in the second cobalt salt, and Mn in the second manganese salt is x:y:(1-xy). The total molar concentration of metals in the second mixed metal salt solution is higher than that in the first mixed metal salt solution. In step 2, the rotation speed is increased to 1.5 to 3 times that in step 1, and the ammonia concentration is increased to 3 to 5 times that in step 1. The total molar concentration of metals in the second mixed metal salt solution is 1.1 to 1.3 times that of the total molar concentration of metals in the first mixed metal salt solution.

2. The preparation method according to claim 1, characterized in that, The total molar concentration of metals in the second mixed metal salt solution is 1.1 to 1.3 times that of the total molar concentration of metals in the first mixed metal salt solution.

3. The preparation method according to claim 1, characterized in that, Also includes: Particles with a preset target particle size are aged, pulped, washed, dried, sieved, and demagnetized.

4. The preparation method according to claim 3, characterized in that, Slurrying was carried out using an aqueous solution of NaOH with a concentration of 0.1 mol / L to 3 mol / L.

5. A ternary precursor, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 4.

6. The ternary precursor according to claim 5, characterized in that, The primary particles of the ternary precursor are in the shape of laths, and the primary particles are stacked vertically, with the vertical direction being the length direction of the laths.

7. A ternary cathode material, characterized in that, The precursor of the ternary cathode material is the ternary precursor as described in claim 5 or 6.

8. A battery, characterized in that, The positive electrode material of the battery is the ternary positive electrode material as described in claim 7.

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