A preparation method of ternary cathode material based on liquid-phase co-precipitation technology

Abstract

The present invention provides a method for preparing a ternary cathode material based on a liquid-phase co-precipitation technique, comprising the following steps: S1. Mix an NCM solution, an NaOH solution, an ammonia water solution, a C6H 11 O7Na solution and a LiOH solution together, control the pH value above 10, heat and react to granulate; S2. After granulation, continue to add the NCM solution, the NaOH solution, the ammonia water solution, the C6H 11 O7Na solution and the LiOH solution to grow the crystal grains; after reacting for 4-10 h, add a sodium hexametaphosphate solution; stop feeding when the crystal grains grow to a particle size of 4-6 μm; S3. Let the slurry obtained in S2 stand and age, add an oxalic acid solution for washing, and then dry and tablet to obtain the target product. In the preparation process of this method, lithium element is added to the nickel-cobalt-manganese ternary solution, and a complexing agent is added to stabilize the doped elements, reducing the precipitation rate difference of each metal ion in the reaction system. The present invention also provides a high-nickel ternary cathode material prepared by using this method, in which the lithium element is uniformly distributed in the ternary cathode material particles.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion battery materials, and in particular to a preparation method of a ternary cathode material based on a liquid-phase co-precipitation technique, and a high-nickel ternary cathode material prepared by using the preparation method. Background Art

[0002] Due to the characteristics of high energy density, light weight, no memory effect, good rate performance, and long cycle life, lithium-ion batteries have been widely used in the fields of electric vehicles, smart grids, and large-scale energy storage. However, with the rapid development of the above fields, higher requirements have been put forward for various performance indicators of lithium-ion batteries, such as energy density and power density.

[0003] The energy density of a lithium-ion battery mainly depends on the energy density of the cathode material. Therefore, developing a new cathode material with good stability, high specific capacity, and good rate performance is the key to the more extensive application of lithium-ion batteries.

[0004] The ternary layered nickel cobalt manganese (NCM) cathode material has the advantages of high voltage, high capacity, long cycle life, good safety performance, no memory effect, and small self-discharge, and is a commonly used cathode material for lithium-ion batteries. However, in the ternary cathode material, since the radius of Ni 2+ is close to that of Li + radius it is easy for Ni 2+ to occupy the Li + site, resulting in cation mixing, which reduces the Li + diffusion channel, and this is not conducive to the extraction and insertion of lithium ions. In addition, the ternary cathode material is an agglomerated granular body composed of many primary grains. If the pressure is too high when making the battery electrode sheet, the secondary particles will break, and the primary particles inside the agglomerate will come into contact with the electrolyte more, accelerating the attenuation of its capacity. For the ternary cathode material with high nickel in the agglomerate, its large specific surface area will also increase its contact with the electrolyte. Therefore, the particle size distribution and microscopic morphology of the nickel cobalt manganese ternary precursor play a decisive role in the performance of the ternary cathode material.

[0005] Currently, the preparation methods of cathode materials mainly include the high-temperature solid-phase method, the sol-gel method, and the method combining the co-precipitation method and the high-temperature solid-phase method. Among them, when using the method combining the co-precipitation method and the high-temperature solid-phase method to prepare the cathode material, the process flow of this preparation method is relatively simple, but it has high energy consumption, a long synthesis cycle, and high-temperature sintering will make the product particles uneven and the crystal form irregular. In addition, the particle size distribution range of the product is wide and the stability is relatively poor.

[0006] The prior art discloses a preparation method of a radial structure spherical NCM811 type ternary cathode material, which includes the following steps: preparing nickel salt, cobalt salt, and manganese salt solutions, where the molar ratio of Ni:Co:Mn is 8:1:1, as solution 1; taking a precipitant and preparing it into solution 2; taking a complexing agent and preparing it into solution 3; adding the complexing agent solution into a reaction kettle as the bottom liquid; adding the above solutions 1, 2, and 3 into the reaction kettle, introducing an inert gas for protection, controlling the total ammonia concentration in the reaction system to be 0.5 - 1.5 mol / L, pH 11.3 - 11.7, temperature 45 - 55 °C, aging for 5 - 15 h, and washing, suction filtering, and drying the reaction product to obtain a precursor; using the precursor and a lithium salt as raw materials, grinding and mixing them evenly; putting the mixed material into a muffle furnace for sintering in an oxygen atmosphere; the sintering is divided into two processes, sintering at 400 - 500 °C for 4 - 8 h; then sintering at 700 - 780 °C for 10 - 15 h; after sintering is completed, cooling to room temperature to obtain the cathode material. When high temperature is required in the subsequent process of this method, it is still easy to produce the above problems of high energy consumption and irregular crystal forms, and the solid lithium salt and the precursor are not evenly mixed, which is likely to cause uneven particles in the high-temperature sintering stage, affecting the stability and uniformity of the cathode material. Summary of the Invention

[0007] Aiming at the deficiencies of the prior art, the present invention provides a preparation method of a ternary cathode material based on the liquid-phase co-precipitation technology. During the preparation process, lithium element is added to the nickel-cobalt-manganese ternary solution, and the doping elements are stabilized by adding a complexing agent, reducing the precipitation rate difference of each metal ion in the reaction system, so that the lithium element is evenly doped in the ternary layered nickel-cobalt-manganese (NCM), realizing uniform co-precipitation. The present invention also provides a high-nickel ternary cathode material prepared by this method. In the ternary cathode material particles, the doped lithium element is evenly distributed, which can effectively increase the lithium ion transmission efficiency.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] A preparation method of a ternary cathode material based on the liquid-phase co-precipitation technology, which includes the following steps:

[0010] S1. Mix the NCM solution, NaOH solution, ammonia water solution, C 6 H 11 O 7 Na solution and LiOH solution together, control the pH value above 10, heat and react to granulate;

[0011] S2. After granulation is completed, continue to add the NCM solution, NaOH solution, ammonia water solution, C 6 H 11 O 7Na solution and LiOH solution to grow grains; after reacting for 4 - 10 h, add sodium hexametaphosphate solution; when the grains grow to a particle size of 4 - 6 μm, stop feeding;

[0012] S3. Let the slurry obtained in S2 stand and age, then add oxalic acid solution for washing. After washing, dry and tablet to obtain the target ternary cathode material.

[0013] As a further description of the technical solution of the present invention, in the granulation stage of S1, it specifically includes the following steps:

[0014] S11. Prepare solutions with the following concentrations respectively: 1 - 3 mol / L NCM solution, 3 - 8 mol / L NaOH solution, 3 - 5 mol / L ammonia water solution, 0.1 - 2 g / L C 6 H 11 O 7 Na solution and 0.5 - 3 g / L LiOH solution;

[0015] S12. Respectively introduce 1 - 3 mol / L NCM solution, 3 - 8 mol / L NaOH solution, 3 - 5 mol / L ammonia water solution, 0.1 - 2 g / L C 6 H 11 O 7 Na solution and 0.5 - 3 g / L LiOH solution into the reaction kettle at flow rates of 5 - 15 ml / min, 1 - 10 ml / min, 2 - 7 ml / min, 2 - 7 Hz and 2 - 7 Hz, control the pH in the reaction kettle system to be 10 - 12, and the reaction temperature to be 70 - 80 °C. After 30 - 40 min, the granulation ends.

[0016] In the granulation stage of the precursor, the present application first introduces the LiOH solution together with the NCM solution, NaOH solution, ammonia water solution and C 6 H 11 O 7 Na solution into the reaction kettle. Compared with the high - temperature sintering solid - phase method, on the one hand, it can be more energy - saving, and on the other hand, it avoids the problem of serious lithium loss in the sintering stage.

[0017] During the introduction process, the present application preferably has the concentration of the LiOH solution as 0.5 - 3 g / L and the flow rate as 2 - 7 Hz, so that lithium ions can be uniformly doped and distributed in the final ternary cathode material.

[0018] As a further description of the technical solution of the present invention, in the co - precipitation reaction generation stage of S2, it specifically includes the following steps:

[0019] S21. After granulation, adjust the flow rates of 1-3 mol / L NCM solution, 3-8 mol / L NaOH solution, 3-5 mol / L ammonia water solution, 0.1-2 g / L C 6 H 11 O 7 Na solution and 0.5-3 g / L LiOH solution to 15-22 ml / min, 5-12 ml / min, 18-23 ml / min, 3-10 Hz, and 3-10 Hz respectively, and carry out reaction to grow grains;

[0020] S22. After reacting for 4-10 h, add 0.5-2 mol / L sodium hexametaphosphate solution at a flow rate of 5-10 Hz;

[0021] S23. When the grains grow to a particle size of 4-6 μm, stop feeding.

[0022] Compared with the granulation stage, the flow rates (flows) of the solutions introduced during the coprecipitation reaction generation stage are all greatly increased. In this reaction stage, the primary particle growth of the grains is relatively fast and more solution is consumed, so the flow rate is increased. After reacting for 4-10 h, the introduced sodium hexametaphosphate solution can improve the dispersion effect of the solution and the sphericity of the particles.

[0023] As a further description of the technical solution of the present invention, in the post-treatment stage of S3, it specifically includes the following steps:

[0024] S31. After standing and aging the slurry in the reaction kettle, wash it with 1-4 mol / L oxalic acid solution;

[0025] S32. After washing, dry the wet material, demagnetize and sieve it, and then press it to obtain the target ternary cathode material.

[0026] As a further description of the technical solution of the present invention, the NCM solution is a nickel-cobalt-manganese ternary precursor, and its chemical composition is Ni x Co y Mn (1-x-y-z) , where 0.80 ≤ x ≤ 1, 0 < y ≤ 0.1, 0 < z ≤ 0.1, 0 < 1 - x - y - z < 0.1.

[0027] As a further description of the technical solution of the present invention, the C 6 H 11 O 7 Na is a chelating agent, and C 6 H 11 O 7 Na (sodium gluconate) is also a structure-directing agent, which can uniformly mix the doped lithium element in the ternary cathode material.

[0028] As a further description of the technical solution of the present invention, the sodium hexametaphosphate is a dispersant. The sodium hexametaphosphate as a dispersant can improve the dispersion effect of the solution and enhance the sphericity of the particles.

[0029] Preferably, a method for preparing a ternary cathode material based on the liquid-phase co-precipitation technique specifically includes the following steps:

[0030] S1. Prepare solutions with the following concentrations respectively: 1.7 mol / L NCM solution, 4.0 mol / L NaOH solution, 3.5 mol / L ammonia water solution, 0.15 g / L C 6 H 11 O 7 Na solution and 1.3 g / L LiOH solution; respectively introduce them into a 100 L reactor at the flow rates of 6 ml / min, 6 ml / min, 4.5 ml / min, 3.7 Hz and 2.8 Hz, control the pH in the reactor system to be 10 - 12, and the reaction temperature to be 75 °C. After 30 min, granulation ends;

[0031] S2. After granulation ends, adjust the flow rates of the NCM solution, NaOH solution, ammonia water solution, C 6 H 11 O 7 Na solution and LiOH solution to 17.5 ml / min, 8.1 ml / min, 15 ml / min, 4.5 Hz and 4.5 Hz respectively; after reacting for 6 h, introduce a 1.5 mol / L sodium hexametaphosphate solution at a flow rate of 6 Hz; when the crystal grains grow to a particle size of 5 μm, stop feeding;

[0032] S3. After the slurry in the reactor is allowed to stand and age, wash it with a 1 mol / L oxalic acid solution; after washing ends, dry the wet material, demagnetize, sieve, and then tablet to obtain the target ternary cathode material.

[0033] Preferably, a method for preparing a ternary cathode material based on the liquid-phase co-precipitation technique specifically includes the following steps:

[0034] S1. Prepare solutions with the following concentrations respectively: 1 mol / L NCM solution, 3 mol / L NaOH solution, 3 mol / L ammonia water solution, 0.1 g / L C 6 H 11 O 7 Na solution and 0.5 g / L LiOH solution; respectively introduce them into a 100 L reactor at the flow rates of 5 ml / min, 1 ml / min, 2 ml / min, 2 Hz and 2 Hz, control the pH in the reactor system to be 10 - 12, and the reaction temperature to be 75 °C. After 30 min, granulation ends;

[0035] S2. After granulation, adjust the flow rates of the NCM solution, NaOH solution, ammonia water solution, C 6 H 11 O 7 Na solution, and LiOH solution to 15 ml / min, 5 ml / min, 18 ml / min, 3 Hz, and 3 Hz respectively; after reacting for 4 h, introduce a 0.5 mol / L sodium hexametaphosphate solution at a flow rate of 5 Hz; when the crystal grains grow to a particle size of 4.5 μm, stop feeding;

[0036] S3. After standing and aging the slurry in the reaction kettle, wash it with a 1 mol / L oxalic acid solution; after washing, dry the wet material, demagnetize and screen it, and then press it into tablets to obtain the target ternary cathode material.

[0037] The present invention also provides a ternary cathode material, which is prepared by using the above-mentioned preparation method of the ternary cathode material. In this ternary cathode material, the doped lithium element can be evenly distributed in the cathode material particles, thereby increasing the lithium ion transport rate, stabilizing the internal lattice structure of the cathode under the high delithiation state, thus significantly improving the specific capacity and cycle stability of the single crystal layered cathode material at the high charging cut-off voltage state, and at the same time effectively reducing side reactions such as oxygen production on the surface of the high-voltage cathode.

[0038] Based on the above technical solutions, compared with the prior art, the technical effects achieved by the present invention are as follows:

[0039] (1) The preparation method of the ternary cathode material provided by the present invention adopts the liquid-phase co-precipitation technology, adds lithium element to the nickel-cobalt-manganese ternary solution, and stabilizes the doped elements by adding a complexing agent, reducing the precipitation rate difference of each metal ion in the reaction system, so that the lithium element is evenly doped in the ternary layered nickel-cobalt-manganese (NCM), realizing uniform co-precipitation.

[0040] (2) For the ternary cathode material obtained by the preparation method of the ternary cathode material provided by the present invention, the doped lithium element can be evenly distributed in the ternary cathode material particles, effectively increasing the lithium ion transport efficiency, stabilizing the internal lattice structure of the cathode under the high delithiation state, and improving the specific capacity and cycle stability of the cathode material. Description of the Drawings

[0041] Figure 1 It is a flow chart of the preparation method of the ternary cathode material of the present invention.

[0042] Figure 2 It is an SEM image of the ternary cathode material prepared in Example 1 of the present invention. Detailed Embodiments

[0043] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below in conjunction with the accompanying drawings and specific embodiments. The preferred embodiments of the present invention are shown in the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present invention more thorough and comprehensive.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0045] Figure 1 is a flowchart of a preparation method for a ternary cathode material, as Figure 1 shown, a preparation method for a ternary cathode material based on a liquid-phase co-precipitation technique, comprising the following steps:

[0046] S1. Granulation stage

[0047] Solutions with the following concentrations are respectively prepared: 1-3 mol / L NCM solution, 3-8 mol / L NaOH solution, 3-5 mol / L ammonia water solution, 0.1-2 g / L C 6 H 11 O 7 Na solution and 0.5-3 g / L LiOH solution;

[0048] The above NCM solution, NaOH solution, ammonia water solution, C 6 H 11 O 7 Na solution and LiOH solution are respectively introduced into the reaction kettle at flow rates of 5-15 ml / min, 1-10 ml / min, 2-7 ml / min, 2-7 Hz and 2-7 Hz, and the pH in the reaction kettle system is controlled at 10-12, and the reaction temperature is 70-80 °C. After 30-40 min, the granulation ends;

[0049] S2. Co-precipitation reaction generation stage

[0050] After the granulation ends, the flow rates of 1-3 mol / L NCM solution, 3-8 mol / L NaOH solution, 3-5 mol / L ammonia water solution, 0.1-2 g / L C 6 H 11 O 7 Na solution and 0.5-3 g / L LiOH solution are respectively adjusted to 15-22 ml / min, 5-12 ml / min, 18-23 ml / min, 3-10 Hz, and 3-10 Hz to carry out reaction growth of crystal grains;

[0051] After reacting for 4 to 10 h, add a sodium hexametaphosphate solution with a concentration of 0.5 to 2 mol / L at a flow rate of 5 to 10 Hz;

[0052] When the grain size grows to 4 - 6 μm, stop feeding.

[0053] S3. Post - treatment stage

[0054] Let the slurry in the reaction kettle stand and age, then wash it with an oxalic acid solution with a concentration of 1 - 4 mol / L;

[0055] After washing, dry the wet material. After the dried material is demagnetized and sieved, it is tableted to obtain the target ternary cathode material.

[0056] Among them, the NCM solution is a nickel - cobalt - manganese ternary precursor, and its chemical composition is Ni x Co y Mn (1-x-y-z) , where 0.80 ≤ x ≤ 1, 0 < y ≤ 0.1, 0 < z ≤ 0.1, 0 < 1 - x - y - z < 0.1.

[0057] C 6 H 11 O 7 Na is a chelating agent and a structure - guiding agent, which makes the doped lithium element evenly mixed in the ternary cathode material.

[0058] Sodium hexametaphosphate is a dispersant, which can improve the dispersion effect of the solution and the sphericity of the particles.

[0059] Example 1

[0060] A ternary cathode material is prepared by the following method. The preparation method specifically includes the following steps:

[0061] S1. First, prepare the following solutions with the following concentrations respectively: a 1.7 mol / L NCM solution, a 4.0 mol / L NaOH solution, a 3.5 mol / L ammonia water solution, a 0.15 g / L C 6 H 11 O 7 Na solution and a 1.3 g / L LiOH solution; then, pass them into a 100 L reaction kettle at flow rates of 6 ml / min, 6 ml / min, 4.5 ml / min, 3.7 Hz and 2.8 Hz respectively, control the pH in the reaction kettle system to be 10 - 12, and the reaction temperature to be 75 °C. Granulation ends after 30 min.

[0062] S2. After granulation, the NCM solution, NaOH solution, ammonia water solution, C 6 H 11 O7 The flow rates of the Na solution and the LiOH solution are adjusted to 17.5 ml / min, 8.1 ml / min, 15 ml / min, 4.5 Hz, and 4.5 Hz respectively; after reacting for 6 h, a 1.5 mol / L sodium hexametaphosphate solution is introduced at a flow rate of 6 Hz; when the crystal grains grow to a particle size of 5 μm, the feeding is stopped.

[0063] S3. After the slurry in the reactor is allowed to stand and age, it is washed with a 1 mol / L oxalic acid solution; after the washing is completed, the wet material is dried, demagnetized, sieved, and then tableted to obtain the target ternary cathode material.

[0064] Figure 1 SEM image of the ternary cathode material prepared in this example, as Figure 1 shown, the particles of the target ternary cathode material have good sphericity and regular crystal forms, which can reduce the agglomeration of secondary particles.

[0065] Example 2

[0066] A ternary cathode material is prepared by the following method, and the preparation method specifically includes the following steps:

[0067] S1. First, prepare the following solutions with the following concentrations: 1 mol / L NCM solution, 3 mol / L NaOH solution, 3 mol / L ammonia water solution, 0.1 g / L C 6 H 11 O 7 Na solution and 0.5 g / L LiOH solution; then, introduce them into a 100 L reactor at flow rates of 5 ml / min, 1 ml / min, 2 ml / min, 2 Hz, and 2 Hz respectively, control the pH in the reactor system to be 10 - 12, and the reaction temperature to be 75 °C. Granulation is completed after 30 min.

[0068] S2. After granulation is completed, adjust the flow rates of the NCM solution, NaOH solution, ammonia water solution, C 6 H 11 O 7 Na solution and LiOH solution to 15 ml / min, 5 ml / min, 18 ml / min, 3 Hz, and 3 Hz respectively; after reacting for 4 h, introduce a 0.5 mol / L sodium hexametaphosphate solution at a flow rate of 5 Hz; when the crystal grains grow to a particle size of 4.5 μm, stop feeding.

[0069] S3. After the slurry in the reactor is allowed to stand and age, it is washed with a 1 mol / L oxalic acid solution; after the washing is completed, the wet material is dried, demagnetized, sieved, and then tableted to obtain the target ternary cathode material.

[0070] Example 3

[0071] A ternary cathode material is prepared by the following method, and the preparation method specifically includes the following steps:

[0072] S1. First, prepare solutions with the following concentrations respectively: 3 mol / L NCM solution, 8 mol / L NaOH solution, 5 mol / L ammonia water solution, 2 g / L C 6 H 11 O 7 Na solution and 3 g / L LiOH solution; then, introduce them into a 100 L reactor at flow rates of 15 ml / min, 10 ml / min, 7 ml / min, 7 Hz, and 7 Hz respectively, control the pH in the reactor system to be 10 - 12, and the reaction temperature to be 75 °C. After 30 min, the granulation is completed.

[0073] S2. After the granulation is completed, adjust the flow rates of the NCM solution, NaOH solution, ammonia water solution, C 6 H 11 O 7 Na solution and LiOH solution to 22 ml / min, 12 ml / min, 23 ml / min, 10 Hz, and 19 Hz respectively; after reacting for 10 h, introduce a 2 mol / L sodium hexametaphosphate solution at a flow rate of 5 Hz; when the grain size grows to 4.5 μm, stop feeding.

[0074] S3. After the slurry in the reactor is left standing and aged, wash it with a 1 mol / L oxalic acid solution; after the washing is completed, dry the wet material, demagnetize, sieve, and then press it to obtain the target ternary cathode material.

[0075] Example 4

[0076] A ternary cathode material is prepared by the following method, and the preparation method specifically includes the following steps:

[0077] S1. First, prepare solutions with the following concentrations respectively: 1.7 mol / L NCM solution, 4.0 mol / L NaOH solution, 3.5 mol / L ammonia water solution, 0.8 g / L C 6 H 11 O 7 Na solution, 1.3 g / L LiOH solution; then, introduce them into a 100 L reactor at flow rates of 6 ml / min, 6 ml / min, 4.5 ml / min, 3.7 Hz, and 2.8 Hz respectively, control the pH in the reactor system to be 10 - 12, and the reaction temperature to be 75 °C. After 30 min, the granulation is completed.

[0078] S2. After the granulation is completed, the NCM solution, NaOH solution, ammonia water solution, C6 H 11 O 7 The flow rates of the Na solution and the LiOH solution were adjusted to 17.5 ml / min, 8.1 ml / min, 15 ml / min, 4.5 Hz, and 4.5 Hz, respectively; after reacting for 6 h, a 1.5 mol / L sodium hexametaphosphate solution was introduced at a flow rate of 6 Hz; when the crystal grains grew to a particle size of 5.5 μm, the feeding was stopped.

[0079] S3. After the slurry in the reaction kettle was allowed to stand and age, it was washed with a 1 mol / L oxalic acid solution; after the washing was completed, the wet material was dried, demagnetized, sieved, and then tableted to obtain the target ternary cathode material.

[0080] Comparative Example 1

[0081] A ternary cathode material was prepared by the following method, and the preparation method specifically included the following steps:

[0082] S1. First, solutions with the following concentrations were prepared respectively: 1 mol / L NCM solution, 1.5 mol / L NaOH solution, and 2.5 mol / L ammonia water solution; then, they were introduced into a 100 L reaction kettle at flow rates of 3.5 ml / min, 6 ml / min, and 4.5 ml / min respectively, and the pH in the reaction kettle system was controlled at 10 - 12, and the reaction temperature was 75 °C. After 30 min, the granulation was completed.

[0083] S2. After the granulation was completed, the flow rates of the NCM solution, the NaOH solution, and the ammonia water solution were adjusted to 17.5 ml / min, 8.1 ml / min, and 15 ml / min respectively; after reacting for 6 h, a 1.5 mol / L sodium hexametaphosphate solution was introduced at a flow rate of 6 Hz; when the crystal grains grew to a particle size of 5.0 μm, the feeding was stopped.

[0084] S3. After the slurry in the reaction kettle was allowed to stand and age, it was washed with pure water; after the washing was completed, the wet material was dried, demagnetized, sieved, and then tableted to obtain the ternary precursor.

[0085] S4. The obtained ternary precursor and solid LiOH were mixed in a ratio of 1:1.05, placed in a muffle furnace and sintered from room temperature to 930 °C, taken out after cooling to room temperature, ground and sieved to obtain the ternary cathode material.

[0086] The ternary cathode materials prepared in Examples 1 - 4 and Comparative Example 1 were taken for testing, and the test results are shown in Table 1.

[0087] Table 1 Performance test data of the ternary cathode materials prepared in Examples 1 - 4 and Comparative Example 1

[0088] ternary cathode material product pH first charge-discharge efficiency Example 1 pH = 7 92.77％ Example 2 pH = 9 89.12％ Example 3 pH = 10 84.65％ Example 4 pH = 8 83.90％ Comparative Example 1 pH = 11 82.34％

[0089] As can be seen from Table 1, compared with Comparative Example 1 in which the ternary cathode material was prepared by the traditional coprecipitation method + high-temperature solid-phase method, the ternary cathode materials in Examples 1-4 were prepared by the liquid-phase coprecipitation reaction generation method, and their initial discharge efficiency was relatively high. Moreover, the initial charge-discharge efficiency of the ternary cathode material in Example 1 reached more than 90%.

[0090] The above content is only an example and illustration of the structure of the present invention. Its description is relatively specific and detailed, but it cannot be understood as a limitation on the scope of the present invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these obvious replacement forms all belong to the protection scope of the present invention.

Claims

1. A preparation method of ternary cathode material based on liquid-phase co-precipitation technology, characterized in that, it includes the following steps: S1. Mix the NCM solution, NaOH solution, ammonia water solution, C 6 H 11 O 7 Na solution and LiOH solution together, control the pH value above 10, heat the reaction, and granulate; S2. After granulation, continue to add NCM solution, NaOH solution, ammonia water solution, C 6 H 11 O 7 Na solution and LiOH solution to grow the crystal grains; after reacting for 4 - 10 h, add sodium hexametaphosphate solution; when the crystal grains grow to a particle size of 4 - 6 μm, stop feeding; S3. Let the slurry obtained in S2 stand and age, then add oxalic acid solution for washing. After the washing is completed, dry and tablet it to obtain the target ternary cathode material.

2. The preparation method of ternary cathode material according to claim 1, characterized in that, in the granulation stage of S1, it specifically includes the following steps: S11. Prepare the following solutions with the respective concentrations: NCM solution at 1 - 3 mol / L, NaOH solution at 3 - 8 mol / L, ammonia solution at 3 - 5 mol / L, C 6 H 11 O 7 Na solution at 0.1 - 2 g / L, and LiOH solution at 0.5 - 3 g / L; S12. Respectively introduce NCM solution with a concentration of 1 - 3 mol / L, NaOH solution with a concentration of 3 - 8 mol / L, ammonia water solution with a concentration of 3 - 5 mol / L, C 6 H 11 O 7 Na solution and LiOH solution with a concentration of 0.5 - 3 g / L into the reaction kettle at flow rates of 5 - 15 ml / min, 1 - 10 ml / min, 2 - 7 ml / min, 2 - 7 Hz and 2 - 7 Hz. Control the pH in the reaction kettle system to be 10 - 12, and the reaction temperature to be 70 - 80 °C. Pelletizing ends after 30 - 40 min.

3. The preparation method of ternary cathode material according to claim 1, characterized in that, in the co-precipitation reaction generation stage of S2, it specifically includes the following steps: After granulation, adjust the flow rates of 1-3 mol / L NCM solution, 3-8 mol / L NaOH solution, 3-5 mol / L ammonia water solution, 0.1-2 g / L C 6 H 11 O 7 Na solution and 0.5-3 g / L LiOH solution to 15-22 ml / min, 5-12 ml / min, 18-23 ml / min, 3-10 Hz, and 3-10 Hz respectively, and carry out reaction to grow grains; S22. After reacting for 4 - 10 h, add a sodium hexametaphosphate solution with a concentration of 0.5 - 2 mol / L at a flow rate of 5 - 10 Hz; S23. When the grain size grows to 4 - 6 μm, stop feeding.

4. The preparation method of ternary cathode material according to claim 1, characterized in that, in the post-treatment stage of S3, it specifically includes the following steps: S31. Let the slurry in the reaction kettle stand and age, then wash it with a 1 - 4 mol / L oxalic acid solution; S32. After the washing is completed, dry the wet material, remove magnetism and sieve it, and then tablet it to obtain the target ternary cathode material.

5. The preparation method of ternary cathode material according to claim 1, characterized in that, The NCM solution is a nickel-cobalt-manganese ternary precursor, and its chemical composition is Ni x Co y Mn (1-x-y-z) , where 0.80 ≤ x ≤ 1, 0 < y ≤ 0.1, 0 < z ≤ 0.1, 0 < 1 - x - y - z < 0.

1.

6. The preparation method of ternary cathode material according to claim 1, characterized in that, it specifically includes the following steps: S1. Prepare the following solutions with different concentrations respectively: 1.7 mol / L NCM solution, 4.0 mol / L NaOH solution, 3.5 mol / L ammonia solution, 0.15 g / L C 6 H 11 O 7 Na solution and 1.3 g / L LiOH solution; Feed them into a 100 L reactor at the flow rates of 6 ml / min, 6 ml / min, 4.5 ml / min, 3.7 Hz and 2.8 Hz respectively, control the pH value in the reactor system to be 10 - 12, and the reaction temperature to be 75 °C. After 30 min, the granulation is completed; S2. After granulation, adjust the flow rates of the NCM solution, NaOH solution, ammonia water solution, C 6 H 11 O 7 Na solution and LiOH solution to 17.5 ml / min, 8.1 ml / min, 15 ml / min, 4.5 Hz and 4.5 Hz respectively; after reacting for 6 h, introduce a 1.5 mol / L sodium hexametaphosphate solution at a flow rate of 6 Hz; when the grain size grows to 5 μm, stop feeding; S3. Let the slurry in the reaction kettle stand and age, then wash it with a 1 mol / L oxalic acid solution; after the washing is completed, dry the wet material, remove magnetism and sieve it, and then tablet it to obtain the target ternary cathode material.

7. The preparation method of ternary cathode material according to claim 1, characterized in that, it specifically includes the following steps: S1. Prepare the following solutions with the respective concentrations: 1 mol / L NCM solution, 3 mol / L NaOH solution, 3 mol / L ammonia solution, 0.1 g / L C 6 H 11 O 7 Na solution, and 0.5 g / L LiOH solution; respectively introduce them into a 100 L reactor at the flow rates of 5 ml / min, 1 ml / min, 2 ml / min, 2 Hz, and 2 Hz, control the pH within the reactor system to be 10 - 12, the reaction temperature to be 75 °C, and end granulation after 30 min; S2. After granulation, adjust the flow rates of the NCM solution, NaOH solution, ammonia water solution, C 6 H 11 O 7 Na solution, and LiOH solution to 15 ml / min, 5 ml / min, 18 ml / min, 3 Hz, and 3 Hz respectively; after reacting for 4 h, introduce a 0.5 mol / L sodium hexametaphosphate solution at a flow rate of 5 Hz; when the crystal grains grow to a particle size of 4.5 μm, stop feeding; S3. Let the slurry in the reaction kettle stand and age, then wash it with a 1 mol / L oxalic acid solution; after the washing is completed, dry the wet material, remove magnetism and sieve it, and then tablet it to obtain the target ternary cathode material.

8. A high-nickel ternary cathode material, characterized in that, it is prepared by using the preparation method of ternary cathode material according to any one of claims 1 - 7.

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