A precursor material and its preparation method and application

Abstract

The invention provides a precursor material and a preparation method and application thereof. The preparation method comprises the following steps: respectively introducing a metal salt solution, a precipitant solution, a complexing agent solution and a polarity regulator into a base liquid to carry out a coprecipitation reaction; regulating the flow of the polarity regulator in stages during the coprecipitation reaction; and after the coprecipitation reaction is completed, carrying out aging and post-treatment to obtain a precursor material. The preparation method achieves the dispersion performance of the raw materials before the reaction, the mass transfer process during the reaction and the morphology control after the reaction by controlling the polarity of the system, thereby solving the problems of nucleation phase separation, poor product sphericity, small explosive particles and uncontrollable surface morphology during the coprecipitation process.

Description

Technical Field

[0001] The invention belongs to the technical field of batteries and relates to a precursor material and a preparation method and application thereof. Background Art

[0002] With the rise of new energy, a large number of positive electrode materials have emerged, from lithium cobalt oxide to ternary precursors, from lithium batteries to sodium batteries, from doping to coating. In the early stages of the preparation of these positive electrode materials, precursors with uniform performance and morphology are basically prepared through co-precipitation reactions, and then the positive electrode materials are obtained through lithium / sodium calcination. In order to improve the performance of positive electrode materials, a variety of electrochemically active materials or materials with other functions are often co-precipitated. However, due to the different precipitation rates of different elements and the different primary crystal forms during precipitation, it is difficult to co-precipitate. For example, Ni / Mn is difficult to co-precipitate in lithium-rich manganese-based precursors, and Cu / Mn is difficult to co-precipitate in sodium battery precursors, which greatly limits the development of new energy materials.

[0003] In the prior art, the conventional process is to achieve co-precipitation by appropriate temperature, pH and high rotation speed. If the properties of the selected materials are greatly different, a complexing agent is needed to assist in achieving co-precipitation. For example, CN 115849463A discloses a high-nickel ternary precursor and a preparation method thereof, comprising the following steps: adding a soluble metal salt, a complexing agent and a precipitant to a base liquid under an inert atmosphere to obtain a mixed solution, and the mixed solution is subjected to a co-precipitation reaction to obtain the high-nickel ternary precursor; the pH of the mixed solution is 11.1-11.6, and in the mixed solution, NH 4+ The concentration of the coprecipitation reaction is 2-4 g / L, and the stirring rate of the coprecipitation reaction is 220-230 rpm; that is, by regulating the pH value, NH 4+ By adjusting parameters such as concentration and stirring rate, the increase in precursor particle size remains stable and the density inside and outside the precursor particles is stable, so that the internal and external structures of the obtained high-nickel ternary precursor particles are uniform.

[0004] However, it is difficult to achieve co-precipitation of elements with large differences simply by controlling the reaction system parameters. Even if chelating agents such as ammonia, oxalic acid, citric acid, EDTA, etc. are introduced into the reaction system to effectively control the morphology and material properties, it will also increase the difficulty of subsequent wastewater treatment and the purity of the treated products.

[0005] Based on the above research, it is necessary to provide a method for preparing a precursor material, which can enable co-precipitation of elements with large differences and achieve effective control of the growth rate, product morphology and performance uniformity. Summary of the invention

[0006] The purpose of the present invention is to provide a precursor material and a preparation method and application thereof. The preparation method realizes the dispersion performance of the raw materials before the reaction, the mass transfer process during the reaction and the morphology control after the reaction by controlling the polarity of the system, and solves the problems of nucleation and phase separation, poor product sphericity, explosive small particles and uncontrollable surface morphology during the co-precipitation process.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing a precursor material, the preparation method comprising the following steps:

[0009] (1) introducing a metal salt solution, a precipitant solution, a complexing agent solution and a polarity regulator into a base solution respectively to carry out a coprecipitation reaction;

[0010] During the coprecipitation reaction, the flow rate of the polarity regulator is adjusted in stages;

[0011] (2) After the coprecipitation reaction in step (1) is completed, aging and post-treatment are performed to obtain a precursor material.

[0012] The present invention introduces a polarity regulator during the coprecipitation process to adjust the polarity of the coprecipitation system, control the mass transfer process and product morphology of the process, and adjusts the flow rate of the polarity regulator in stages during the coprecipitation process, which can achieve uniform nucleation without phase separation, good sphericity of the product, avoid the explosion of small particles, and controllable surface morphology. At the same time, the overall preparation process of the present invention is simple, and only the flow rate of the polarity regulator needs to be adjusted, and there is no need to perform multi-condition regulation.

[0013] Preferably, the different stages in the staged regulation in step (1) include a starting stage, a falling flow stage, a maintaining stage and a sudden increase stage which are performed in sequence;

[0014] Preferably, the flow rate of the polarity regulator in the maintenance stage is smaller than that in the initial stage.

[0015] Preferably, the flow rate of the polarity regulator in the surge stage is greater than that in the initial stage.

[0016] The present invention adjusts the flow of the polarity regulator in the initial stage, the falling flow stage, the maintaining stage and the sudden increase stage to realize the control of the reaction process, ensure rapid nucleation in the early stage without phase separation and agglomeration, and as the flow of the polarity regulator decreases, the particles gradually grow and the sphericity is gradually restored, and then the flow of the polarity regulator is suddenly increased, which can firstly reduce the adsorption amount of surface Na and S ions and simplify the washing process, and secondly reduce the reaction speed, so that the surface crystal becomes dense without oxidation cracking, and further can avoid the explosion of small particles in the later stage.

[0017] Preferably, in the initial stage, the flow rate of the polarity regulator is 20-25% of the flow rate of the metal salt solution, for example, it can be 20%, 21%, 22%, 23%, 24% or 25%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0018] Preferably, in the descending stage, the decreasing rate of the flow rate of the polarity regulator is 0.02-0.07 L / h, for example, it can be 0.02 L / h, 0.04 L / h, 0.06 L / h or 0.07 L / h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0019] Preferably, during the maintenance stage, the flow rate of the polarity regulator is 10-15% of the flow rate of the metal salt solution, for example, it can be 10%, 11%, 12%, 13%, 14% or 15%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0020] Preferably, in the surge stage, the flow rate of the polarity regulator is 45-55% of the flow rate of the metal salt solution, for example, it can be 45%, 47.5%, 50%, 52.5% or 55%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] Preferably, after the coprecipitation reaction in step (1) is carried out for 1 / 7 to 1 / 9 of the total coprecipitation time, for example, it can be 1 / 7, 1 / 8 or 1 / 9, the initial stage ends, the flow rate of the polarity regulator is adjusted, and the downflow stage begins.

[0022] Due to different coprecipitation systems and different particle size requirements, the total time for the coprecipitation reaction is different. Therefore, the present invention does not specifically limit the total time of the coprecipitation reaction, and those skilled in the art can make a reasonable selection according to the requirements.

[0023] Preferably, in the falling flow stage, after the flow rate of the polarity regulator drops to 10-15% of the flow rate of the metal salt solution, for example, it can be 10%, 11%, 12%, 13%, 14% or 15%, it remains unchanged and enters the maintaining stage.

[0024] Preferably, when the coprecipitation reaction in step (1) is carried out until the median particle size of the product is 0.5-2 μm away from the stopping point, for example, 0.5 μm, 1 μm or 2 μm, the flow rate of the polarity regulator is adjusted to enter the sudden increase stage from the maintenance stage.

[0025] The timing of adjustment in each stage of the present invention is coordinated with the flow rate in each stage, which affects the effect of the polarity regulator in each stage. Since rapid co-precipitation nucleation must be ensured in the initial stage, the polarity regulator adjusts the flow rate to reduce after nucleation to allow the particles to grow and repair the sphericity of the particles at the same time; that is, if the timing of entering the downflow stage is too early, there will be phase separation in the system and even particle agglomeration; if the timing of entering the downflow stage is too late, the particle growth and particle sphericity will be affected; if the timing of entering the sudden increase stage is too early, the later reaction time will be extended, and the risk of nuclear explosion and cracking will easily occur; if the timing of entering the sudden increase stage is too late, the surface sphericity will be poor.

[0026] Preferably, the polarity regulator in step (1) comprises an alcohol solvent.

[0027] The present invention adopts an alcohol solvent compatible with water to adjust the polarity of the system, thereby ensuring that the addition of a polarity regulator will not affect the normal progress of the coprecipitation reaction.

[0028] Preferably, the alcohol solvent includes methanol and / or ethanol.

[0029] Preferably, the base solution in step (1) comprises a precipitant solution, a complexing agent solution and a polarity regulator.

[0030] The present invention also adds a polarity regulator into the base liquid, which can control the dispersibility of the raw materials before the reaction and match the staged regulation steps.

[0031] Preferably, the volume of the polarity regulator in the base solution of step (1) accounts for 5-50% of the total volume of the base solution, for example, it can be 5%, 10%, 20%, 30%, 40% or 50%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0032] Preferably, the metal salt solution in step (1) comprises nickel ions, cobalt ions and M element ions, wherein the M element comprises any one or a combination of at least two of Mn, Fe, Cu, Al or Mg.

[0033] Preferably, the metal salt includes any one of sulfate, nitrate or chloride, or a combination of at least two of them.

[0034] Preferably, the precipitant solution in step (1) comprises sodium hydroxide solution.

[0035] Preferably, the complexing agent solution in step (1) comprises aqueous ammonia.

[0036] Preferably, the temperature of the coprecipitation reaction in step (1) is 40-60°C, for example, 40°C, 50°C or 60°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0037] Preferably, in the metal salt solution of step (1), the concentration of total metal ions is 80-120 g / L, for example, 80 g / L, 90 g / L, 100 g / L, 110 g / L or 120 g / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0038] Preferably, in the precipitant solution of step (1), the mass percentage of the solute is 30-42%, for example, 30%, 35%, 40% or 42%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0039] Preferably, in the complexing agent solution of step (1), the mass percentage of the solute is 10-20%, for example, 10%, 15% or 20%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0040] Preferably, the flow rate of the metal salt solution when passing into the base liquid in step (1) is 15-45 L / h, for example, it can be 15 L / h, 25 L / h, 35 L / h or 45 L / h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0041] Preferably, the flow rate of the precipitant solution when passing into the base liquid in step (1) is 5-30 L / h, for example, it can be 5 L / h, 10 L / h, 20 L / h or 30 L / h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0042] Preferably, the flow rate of the complexing agent solution when passing into the base liquid in step (1) is 5-30 L / h, for example, it can be 5 L / h, 10 L / h, 20 L / h or 30 L / h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0043] Preferably, the coprecipitation process in step (1) is accompanied by stirring.

[0044] Preferably, the aging time in step (2) is 2-18 hours, for example, 2 hours, 5 hours, 10 hours, 15 hours or 18 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0045] Preferably, the post-treatment in step (2) comprises filtering, washing, drying and screening performed in sequence.

[0046] As a preferred technical solution of the preparation method of the present invention, the preparation method comprises the following steps:

[0047] (1) introducing a metal salt solution, a precipitant solution, a complexing agent solution and a polarity regulator into a base liquid respectively, and performing a coprecipitation reaction at 40-60° C.; wherein the base liquid comprises a precipitant solution, a complexing agent solution and a polarity regulator, and the volume of the polarity regulator in the base liquid accounts for 5-50% of the total volume of the base liquid;

[0048] During the coprecipitation reaction, in the initial stage, the flow rate of the polarity regulator is 20-25% of the flow rate of the metal salt solution. When the coprecipitation reaction is carried out to 1 / 7 to 1 / 9 of the total coprecipitation time, the initial stage ends and the flow reduction stage begins. The flow rate of the polarity regulator is adjusted at a decreasing rate of 0.02-0.07 L / h until the flow rate of the polarity regulator is 10-15% of the flow rate of the metal salt solution. The maintenance stage begins. When the median particle size of the product is 0.5-2 μm away from the stop, the flow rate of the polarity regulator is adjusted to 45-55% of the flow rate of the metal salt solution, and the maintenance stage enters the sudden increase stage.

[0049] (2) After the coprecipitation reaction in step (1) is completed, aging, filtering, washing, drying and screening are performed to obtain a precursor material.

[0050] In a second aspect, the present invention provides a precursor material, which is prepared by the preparation method described in the first aspect.

[0051] In a third aspect, the present invention provides a battery, wherein the positive electrode material of the battery is prepared from the precursor material described in the second aspect.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] The present invention controls the dispersion performance of raw materials before the reaction, the mass transfer process during the reaction, and the morphology after the reaction by controlling the polarity of the reaction system, and adjusts the flow rate of the polarity regulator at different stages to achieve the adjustment of the polarity of the coprecipitation system, achieve uniform nucleation of the product without phase separation, and achieve good sphericity of the product, which can avoid the explosion of small particles during the coprecipitation process and achieve the effect of controllable product surface morphology. At the same time, the overall preparation process of the present invention is simple, and only the flow rate of the polarity regulator needs to be adjusted, without the need for multi-condition regulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 This is a morphology image of the precursor material obtained in Example 1 of the present invention at a magnification of 10000X;

[0055] Figure 2 This is a morphology picture of the precursor material obtained in Comparative Example 1 of the present invention at a magnification of 10000X. DETAILED DESCRIPTION

[0056] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0057] Example 1

[0058] This embodiment provides a method for preparing a precursor material, and the preparation method comprises the following steps:

[0059] (1) introducing a metal salt solution having a total metal ion concentration of 120 g / L, a precipitant solution having a solute mass percentage of 40%, a complexing agent solution having a solute mass percentage of 10%, and a polarity regulator into a base liquid respectively, and carrying out a coprecipitation reaction in a reactor at a temperature of 45° C. under stirring; wherein the base liquid comprises a precipitant solution, a complexing agent solution, and a polarity regulator, the volume of the polarity regulator in the base liquid accounts for 10% of the total volume of the base liquid, the flow rate of the metal salt solution is 30 L / h, the flow rate of the precipitant solution is 15 L / h, and the flow rate of the complexing agent solution into the base liquid is 15 L / h;

[0060] The polarity regulator is anhydrous ethanol, the metal salt solution includes nickel ions, cobalt ions, manganese ions and iron ions, the precipitant solution is sodium hydroxide solution, and the complexing agent is ammonia water;

[0061] During the coprecipitation reaction, in the initial stage, the flow rate of the polarity regulator is 20% of the flow rate of the metal salt solution, specifically 6 L / h. When the coprecipitation reaction is carried out to 1 / 8 of the total coprecipitation time, the initial stage ends and enters the downflow stage, and the flow rate of the polarity regulator is adjusted at a descending rate of 0.05 L / h until the flow rate of the polarity regulator is 10% of the flow rate of the metal salt solution, specifically 3 L / h, and enters the maintenance stage. When the median particle size of the product is 1 μm away from the stop, the flow rate of the polarity regulator is adjusted to 50% of the flow rate of the metal salt solution, specifically 15 L / h, and the maintenance stage enters the sudden increase stage, and the reaction continues to the target particle size;

[0062] (2) After the coprecipitation reaction in step (1) is completed, the product is aged for 6 hours, and then filtered, washed, dried and sieved to obtain a precursor material. The morphology of the obtained precursor material at a magnification of 10000X is as follows: Figure 1 shown.

[0063] Example 2

[0064] This embodiment provides a method for preparing a precursor material, and the preparation method comprises the following steps:

[0065] (1) introducing a metal salt solution having a total metal ion concentration of 100 g / L, a precipitant solution having a solute mass percentage of 35%, a complexing agent solution having a solute mass percentage of 15%, and a polarity regulator into a base liquid respectively, and carrying out a coprecipitation reaction in a reactor at a temperature of 40° C. under stirring; wherein the base liquid comprises a precipitant solution, a complexing agent solution, and a polarity regulator, the volume of the polarity regulator in the base liquid accounts for 50% of the total volume of the base liquid, the flow rate of the metal salt solution introduced is 15 L / h, the flow rate of the precipitant solution introduced is 5 L / h, and the flow rate of the complexing agent solution introduced into the base liquid is 5 L / h;

[0066] The polarity regulator is anhydrous ethanol, the metal salt solution includes nickel ions, cobalt ions, manganese ions and iron ions, the precipitant solution is sodium hydroxide solution, and the complexing agent is ammonia water;

[0067] During the coprecipitation reaction, in the initial stage, the flow rate of the polarity regulator is 25% of the flow rate of the metal salt solution, specifically 3.75 L / h. When the coprecipitation reaction is carried out to 1 / 7 of the total coprecipitation time, the initial stage ends and enters the downflow stage, and the flow rate of the polarity regulator is adjusted at a descending rate of 0.02 L / h until the flow rate of the polarity regulator is 15% of the flow rate of the metal salt solution, specifically 2.25 L / h, and enters the maintenance stage. When the median particle size of the product is 0.5 μm away from stopping the reactor, the flow rate of the polarity regulator is adjusted to 55% of the flow rate of the metal salt solution, specifically 8.25 L / h, and the maintenance stage enters the sudden increase stage, and the reaction continues to the target particle size;

[0068] (2) After the coprecipitation reaction in step (1) is completed, the product is aged for 18 hours, and then filtered, washed, dried and sieved to obtain a precursor material.

[0069] Example 3

[0070] This embodiment provides a method for preparing a precursor material, and the preparation method comprises the following steps:

[0071] (1) introducing a metal salt solution having a total metal ion concentration of 80 g / L, a precipitant solution having a solute mass percentage of 30%, a complexing agent solution having a solute mass percentage of 20%, and a polarity regulator into a base liquid respectively, and carrying out a coprecipitation reaction in a reactor at a temperature of 60° C. under stirring; wherein the base liquid comprises a precipitant solution, a complexing agent solution, and a polarity regulator, the volume of the polarity regulator in the base liquid accounts for 5% of the total volume of the base liquid, the flow rate of the metal salt solution is 45 L / h, the flow rate of the precipitant solution is 30 L / h, and the flow rate of the complexing agent solution into the base liquid is 30 L / h;

[0072] The polarity regulator is anhydrous ethanol, the metal salt solution includes nickel ions, cobalt ions, manganese ions and iron ions, the precipitant solution is sodium hydroxide solution, and the complexing agent is ammonia water;

[0073] During the coprecipitation reaction, in the initial stage, the flow rate of the polarity regulator is 20% of the flow rate of the metal salt solution, specifically 9 L / h. When the coprecipitation reaction is carried out to 1 / 9 of the total coprecipitation time, the initial stage ends and enters the descending stage, and the flow rate of the polarity regulator is adjusted at a descending rate of 0.07 L / h until the flow rate of the polarity regulator is 15% of the flow rate of the metal salt solution, specifically 6.75 L / h, and enters the maintenance stage. When the median particle size of the product is 2 μm away from the stop, the flow rate of the polarity regulator is adjusted to 45% of the flow rate of the metal salt solution, specifically 20.25 L / h, and the maintenance stage enters the sudden increase stage, and the reaction continues to the target particle size;

[0074] (2) After the coprecipitation reaction in step (1) is completed, the product is aged for 2 hours, and then filtered, washed, dried and sieved to obtain a precursor material.

[0075] Example 4

[0076] This embodiment provides a method for preparing a precursor material. The preparation method is the same as that of Embodiment 1 except that step (1) does not carry out a sudden increase stage and the coprecipitation reaction continues in a maintenance stage until the reaction is stopped.

[0077] Example 5

[0078] This embodiment provides a method for preparing a precursor material. The preparation method is the same as that of Embodiment 1 except that in step (1), the flow rate of the polarity regulator is directly adjusted from 20% of the flow rate of the metal salt solution to 10% before entering the maintenance stage without performing the downflow stage.

[0079] Example 6

[0080] This embodiment provides a method for preparing a precursor material, which is the same as that of Embodiment 1 except that in step (1), when the coprecipitation reaction is carried out to 1 / 6 of the total coprecipitation time, the initial stage ends and the downflow stage begins.

[0081] Example 7

[0082] This embodiment provides a method for preparing a precursor material, which is the same as that of Embodiment 1 except that in step (1), when the coprecipitation reaction is carried out to 1 / 10 of the total coprecipitation time, the initial stage ends and the downflow stage begins.

[0083] Example 8

[0084] This embodiment provides a method for preparing a precursor material, which is the same as that of Embodiment 1 except that in step (1), when the median particle size of the product is still 0.2 μm away from stopping the process, the flow rate of the polarity regulator is adjusted to 50% of the flow rate of the metal salt solution.

[0085] Example 9

[0086] This embodiment provides a method for preparing a precursor material, which is the same as that of Embodiment 1 except that in step (1), when the median particle size of the product is 3 μm away from stopping the process, the flow rate of the polarity regulator is adjusted to 50% of the flow rate of the metal salt solution.

[0087] Example 10

[0088] This embodiment provides a method for preparing a precursor material. The preparation method is the same as that of Embodiment 1 except that the base liquid in step (1) does not include a polarity regulator.

[0089] Comparative Example 1

[0090] This comparative example provides a method for preparing a precursor material, which is the same as Example 1 except that no polarity regulator is introduced in step (1) and the base liquid does not include a polarity regulator;

[0091] The morphology of the precursor material obtained in this comparative example at a magnification of 10000X is as follows Figure 2 shown.

[0092] Comparative Example 2

[0093] This comparative example provides a method for preparing a precursor material, which is the same as Example 1 except that in step (1), the polarity regulator is not subjected to stage-by-stage flow adjustment and is introduced at the flow rate of the initial stage until the reactor is stopped.

[0094] The diameter distance and sphericity of the precursor materials obtained in the above embodiments and comparative examples are shown in Table 1, wherein the diameter distance = (D90-D10) / D50, indicating the distribution width of the particles. The larger the diameter distance, the wider the distribution width.

[0095] Table 1

[0096] Diameter Sphericity Example 1 0.6 0.8 Example 2 0.62 0.77 Example 3 0.7 0.78 Example 4 0.62 0.7 Example 5 0.9 0.8 Example 6 0.65 0.74 Example 7 0.65 0.75 Example 8 0.62 0.6 Example 9 0.5 0.8 Example 10 1.0 0.5 Comparative Example 1 1.2 0.3 Comparative Example 2 1.5 0.7

[0097] From Table 1 we can see that:

[0098] The product obtained by the method provided by the present invention has a narrow particle size distribution range, high sphericity, no burst of small particles, and only needs to change the flow rate of the polarity regulator; by combining Example 1 with Comparative Example 1, Figure 1 and Figure 2It can be seen that in Comparative Example 1, no polarity regulator was added during the entire coprecipitation process, and the obtained product had a low sphericity, small particles were generated, and the product particle size distribution was wide and uneven, while the product obtained by the present invention had a high sphericity, a uniform particle size distribution, and no small particles were generated; it can be seen from Example 1 and Comparative Example 2 that even if a polarity regulator is added to the system, if the polarity is not adjusted according to different stages, the role of the polarity regulator cannot be exerted, and the beneficial effects of the present invention cannot be achieved; it can be seen from Example 1 and Examples 4-5 that the polarity regulator of the present invention adjusts the flow rate at different stages, which can effectively control the particle generation, thereby effectively controlling the generation of small particles and the sphericity of the particles; it can be seen from Examples 1 and Examples 6-10 that the timing of performing different stages and the polarity regulator in the base liquid will also affect the coprecipitation reaction.

[0099] In summary, the present invention provides a precursor material and a preparation method and application thereof. The preparation method realizes the dispersion performance of the raw materials before the reaction, the mass transfer process during the reaction and the morphology control after the reaction by controlling the polarity of the system, and solves the problems of nucleation and phase separation, poor product sphericity, explosion of small particles and uncontrollable surface morphology during the co-precipitation process.

[0100] The above description is only a specific implementation mode 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 thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a precursor material, characterized in that: The preparation method comprises the following steps: (1) introducing a metal salt solution, a precipitant solution, a complexing agent solution and a polarity regulator into a base solution respectively to carry out a coprecipitation reaction; during the coprecipitation reaction, the flow rate of the polarity regulator is adjusted in stages; (2) After the coprecipitation reaction in step (1) is completed, aging and post-treatment are performed to obtain a precursor material; The different stages in the step-by-step regulation in step (1) include a starting stage, a falling flow stage, a maintaining stage and a sudden increase stage, which are performed in sequence; the flow rate of the polarity regulator in the maintaining stage is smaller than that in the starting stage; the flow rate of the polarity regulator in the sudden increase stage is larger than that in the starting stage; When the coprecipitation reaction in step (1) is carried out until the median particle size of the product is 0.5-2 μm away from the stopping point, the flow rate of the polarity regulator is adjusted to enter the sudden increase stage from the maintenance stage; The polarity regulator in step (1) includes an alcohol solvent.

2. The preparation method according to claim 1, characterized in that: In the initial stage, the flow rate of the polarity regulator is 20-25% of the flow rate of the metal salt solution.

3. The preparation method according to claim 1, characterized in that: In the descending flow stage, the decreasing rate of the flow rate of the polarity regulator is 0.02-0.07 L / h.

4. The preparation method according to claim 1, characterized in that: In the maintenance stage, the flow rate of the polarity regulator is 10-15% of the flow rate of the metal salt solution.

5. The preparation method according to claim 1, characterized in that: In the sudden increase stage, the flow rate of the polarity regulator is 45-55% of the flow rate of the metal salt solution.

6. The preparation method according to claim 1, characterized in that: After the coprecipitation reaction in step (1) is carried out for 1 / 7 to 1 / 9 of the total coprecipitation time, the initial stage ends, the flow rate of the polarity regulator is adjusted, and the downflow stage begins.

7. The preparation method according to claim 1, characterized in that: In the falling flow stage, after the flow rate of the polarity regulator drops to 10-15% of the flow rate of the metal salt solution, it remains unchanged and enters the maintaining stage.

8. The preparation method according to claim 1, characterized in that: The alcohol solvent includes methanol and / or ethanol.

9. The preparation method according to claim 1, characterized in that: The base solution in step (1) comprises a precipitant solution, a complexing agent solution and a polarity regulator.

10. The preparation method according to claim 9, characterized in that: The volume of the polarity regulator in the base solution in step (1) accounts for 5-50% of the total volume of the base solution.

11. The preparation method according to claim 1, characterized in that: The metal salt solution in step (1) comprises nickel ions, cobalt ions and M element ions, wherein the M element comprises any one of Mn, Fe, Cu, Al or Mg or a combination of at least two thereof.

12. The preparation method according to claim 1, characterized in that: The precipitant solution in step (1) comprises sodium hydroxide solution.

13. The preparation method according to claim 1, characterized in that: The complexing agent solution in step (1) includes aqueous ammonia.

14. The preparation method according to claim 1, characterized in that: The temperature of the coprecipitation reaction in step (1) is 40-60°C.

15. The preparation method according to claim 1, characterized in that: In the metal salt solution of step (1), the concentration of total metal ions is 80-120 g / L.

16. The preparation method according to claim 1, characterized in that: In the precipitant solution of step (1), the mass percentage of the solute is 30-42%.

17. The preparation method according to claim 1, characterized in that: In the complexing agent solution of step (1), the mass percentage of the solute is 10-20%.

18. The preparation method according to claim 1, characterized in that: The flow rate of the metal salt solution when passing into the base liquid in step (1) is 15-45 L / h.

19. The preparation method according to claim 1, characterized in that: The flow rate of the precipitant solution when passing into the base liquid in step (1) is 5-30 L / h.

20. The preparation method according to claim 1, characterized in that: The flow rate of the complexing agent solution when passing into the base liquid in step (1) is 5-30 L / h.

21. The preparation method according to claim 1, characterized in that: The aging time in step (2) is 2-18 hours.

22. The preparation method according to claim 1, characterized in that: The post-treatment in step (2) includes filtering, washing, drying and screening in sequence.

23. The preparation method according to claim 1, characterized in that: The preparation method comprises the following steps: (1) introducing a metal salt solution, a precipitant solution, a complexing agent solution and a polarity regulator into a base liquid respectively, and performing a coprecipitation reaction at 40-60° C.; wherein the base liquid comprises a precipitant solution, a complexing agent solution and a polarity regulator, and the volume of the polarity regulator in the base liquid accounts for 5-50% of the total volume of the base liquid; During the coprecipitation reaction, in the initial stage, the flow rate of the polarity regulator is 20-25% of the flow rate of the metal salt solution. When the coprecipitation reaction is carried out to 1 / 7 to 1 / 9 of the total coprecipitation time, the initial stage ends and the flow reduction stage begins. The flow rate of the polarity regulator is adjusted at a decreasing rate of 0.02-0.07 L / h until the flow rate of the polarity regulator is 10-15% of the flow rate of the metal salt solution. The maintenance stage begins. When the median particle size of the product is 0.5-2 μm away from the stop, the flow rate of the polarity regulator is adjusted to 45-55% of the flow rate of the metal salt solution, and the maintenance stage enters the sudden increase stage. (2) After the coprecipitation reaction in step (1) is completed, aging, filtering, washing, drying and screening are performed to obtain a precursor material.

24. A precursor material, characterized in that The precursor material is prepared by the preparation method according to any one of claims 1 to 23.

25. A battery, characterized in that: The positive electrode material of the battery is prepared from the precursor material described in claim 24.

Images