Preparation method of aluminum-doped cobalt carbonate

Abstract

The invention relates to the technical field of preparation of high-voltage lithium battery materials, in particular to a preparation method of aluminum-doped cobalt carbonate. The preparation method comprises the following steps: obtaining a cobalt carbonate seed crystal; a soluble mixed salt solution containing cobalt salt and aluminum salt is added into the cobalt carbonate seed crystal, then the soluble mixed salt solution and ammonium bicarbonate feed liquid are added in a parallel flow feeding mode for mixed reaction, growth and drying treatment are carried out, and the aluminum-doped cobalt carbonate is prepared. According to the preparation method, cobalt carbonate seed crystals are obtained firstly, in the process of preparing aluminum-doped cobalt carbonate, a soluble mixed salt solution containing cobalt salt and aluminum salt is added in advance, Co < 2 + > of a reaction system is supplemented, OH <->, Al < 3 + >, CO3 < 2-> and Co < 2 + > released by the reaction system are induced to generate stable-crystalline-state small-size basic cobalt aluminum carbonate, and therefore generation of columnar objects is blocked, and industrial production is facilitated.

Description

Technical Field

[0001] The present application belongs to the technical field of high-voltage lithium battery material preparation, and in particular to a method for preparing aluminum-doped cobalt carbonate. Background Art

[0002] As the global mobile communication network gradually moves towards the 5G era, 3C consumer electronic products represented by 5G smartphones have put forward higher requirements for the battery life and volume energy density of lithium cobalt oxide batteries. Increasing the charging voltage of lithium cobalt oxide batteries is one of the important ways to increase the energy density of batteries. As the cut-off voltage of lithium cobalt oxide increases, its specific capacity increases significantly. However, as the charging voltage increases, the structural stability of lithium cobalt oxide is poor, resulting in rapid capacity decay.

[0003] In order to provide structural stability of lithium cobalt oxide at high voltage, the existing technology usually uses aluminum doping for processing. The development trend of high-voltage LCO technology is to pre-dope aluminum into the precursor cobalt tetroxide, and put forward higher requirements for the uniformity of aluminum doping in cobalt tetroxide. Doped small-particle cobalt tetroxide is the key raw material for high-voltage LCO at present. It is used to fill the gaps in large-particle products and increase the compaction density of positive electrode materials. The terminal market is 3C electronic products such as 5G mobile phones and tablets. In addition, small-particle products play a direct and important role in reducing the DCR of batteries, and the appropriate addition ratio can also greatly improve the cycle performance of batteries.

[0004] Aluminum-doped small-particle cobalt tetroxide is mainly produced by wet coprecipitation-thermal decomposition process. There are two synthetic routes for wet coprecipitation: carbonate and oxyhydroxide. The carbonate route has become the mainstream production process because of its easy control of morphology and particle size. The oxyhydroxide route is due to the fact that Co 3+ and Al 3+ The same valence state and similar ionic radius, Al 3+ Can replace Co 3+ A solid solution is formed in the position, so the uniformity of aluminum doping is better than that of the carbonate system. However, the morphology and particle size of the hydroxycobalt route are difficult to control, and the synthesis process requires chelating agents such as EDTA, tartaric acid, etc., which brings environmental problems such as high Co content and high COD in the wastewater. The carbonate wet aluminum doping technology has made great progress in recent years, especially in the control of the uniformity of aluminum doping in large-particle cobalt carbonate. The inner layer of the particles is designed to be amorphous and adsorbed and dispersed in the cobalt carbonate matrix, and the outer layer of aluminum is stable crystalline aluminum to prevent hydrolysis and segregation during washing and drying. The same technical solution is used to synthesize small-particle aluminum-doped cobalt carbonate, which will produce some new technical problems. For example, aluminum-containing columns will precipitate during the wet synthesis process, resulting in poor aluminum uniformity, which will affect the performance during the application process and is not conducive to widespread application in industry. Summary of the invention

[0005] The purpose of the present application is to provide a method for preparing aluminum-doped cobalt carbonate, aiming to solve the problems of easy precipitation of aluminum-containing columns, uneven aluminum doping and uncontrollable product morphology and particle size in the preparation method of aluminum-doped small-particle cobalt carbonate in the prior art.

[0006] In order to achieve the above application purpose, the technical solution adopted in this application is as follows:

[0007] In a first aspect, the present application provides a method for preparing aluminum-doped cobalt carbonate, comprising the following steps:

[0008] obtaining cobalt carbonate seed crystals;

[0009] A soluble mixed salt solution containing cobalt salt and aluminum salt is first added to the cobalt carbonate seed crystal, and then the soluble mixed salt solution containing cobalt salt and aluminum salt and ammonium bicarbonate feed liquid are added in a parallel flow manner for mixed reaction, growth, and drying to prepare aluminum-doped cobalt carbonate.

[0010] In a second aspect, the present application provides an aluminum-doped cobalt carbonate, which is prepared by the above-mentioned method for preparing aluminum-doped cobalt carbonate.

[0011] The first aspect of the present application provides a method for preparing aluminum-doped cobalt carbonate. The method first obtains cobalt carbonate seed crystals, and in the process of preparing aluminum-doped cobalt carbonate, pre-adds a mixed salt solution, wherein the mixed salt solution includes a cobalt salt solution, so that the Co in the reaction system can be supplemented in advance. 2+ , induced reaction system releases OH - 、Al 3+ , CO 3 2- With Co 2+ Stable crystalline small-sized basic aluminum cobalt carbonate is generated, thereby preventing the generation of columnar objects; the preparation method is simple and easy to operate, the reaction conditions are mild, and it is green and environmentally friendly; and the aluminum element is evenly distributed in the prepared aluminum-doped cobalt carbonate material, and columnar impurities are completely eliminated, which is conducive to industrial production.

[0012] The aluminum-doped cobalt carbonate provided in the second aspect of the present application is prepared by the above-mentioned preparation method. Therefore, the obtained aluminum-doped cobalt carbonate is stable crystalline small-sized particles with controllable morphology and particle size, uniform distribution of aluminum elements, and no aluminum columns will precipitate in the material, which is conducive to wide application. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0014] Figure 1 This is an electron microscope image of the primary growth particles of cobalt carbonate obtained in Example 1 of the present application and the product of aluminum-doped cobalt carbonate.

[0015] Figure 2 This is an electron microscope image of the primary growth particles of cobalt carbonate obtained in Example 2 of the present application and the product of aluminum-doped cobalt carbonate.

[0016] Figure 3 This is an electron microscope image of the primary growth particles of cobalt carbonate obtained in Example 3 of the present application and the product of aluminum-doped cobalt carbonate.

[0017] Figure 4 These are electron microscope analysis images of the primary growth particles of cobalt carbonate and the product aluminum-doped cobalt carbonate provided in Comparative Example 1 of the present application.

[0018] Figure 5 These are electron microscope analysis images of the primary growth particles of cobalt carbonate and the product aluminum-doped cobalt carbonate provided in Comparative Example 2 of the present application.

[0019] Figure 6 This is an analysis chart of the aluminum signal values ​​of the aluminum-doped cobalt carbonate product obtained in Example 3 of the present application and the aluminum-doped cobalt carbonate containing columns obtained in Comparative Example 1. DETAILED DESCRIPTION

[0020] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0021] In this application, the term "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0022] In this application, "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple, respectively.

[0023] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0024] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "an" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0025] The weight of the relevant components mentioned in the embodiment description of the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the embodiment description of the present application, it is within the scope disclosed in the embodiment description of the present application. Specifically, the mass in the embodiment description of the present application can be μg, mg, g, kg and other mass units known in the chemical industry.

[0026] The terms "first" and "second" are used only for descriptive purposes to distinguish objects such as substances from each other, and should not be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. For example, without departing from the scope of the embodiments of the present application, the first XX may also be referred to as the second XX, and similarly, the second XX may also be referred to as the first XX. Thus, features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0027] At present, the carbonate system is used for wet aluminum doping. The wet synthesis temperature is relatively high, at 38-50°C. The ammonium bicarbonate in the reaction system decomposes seriously, and two situations will occur: ① The amount of ammonium bicarbonate added as the precipitant is large, the pH value is high, greater than 7.5, and the reaction system is relatively Co 2+ Lack of, forming a large number of columns, resulting in aluminum enrichment. ② The amount of precipitant added is relatively small, relative to Co 2+It is rich and will produce large-sized honeycomb-shaped basic aluminum ammonium carbonate, forming another enriched form of aluminum. Although some existing technologies adjust the synthesis temperature, in order to control the morphology and particle size, multiple cycles of feeding are required, that is, the repeated process of feeding, settling, extracting the supernatant, and feeding. Amorphous aluminum precipitates columnar substances during the sedimentation and supernatant extraction process. Since the next time the feeding reaction system Co is started, 2+ Lack of aluminum, the columnar material grows further, resulting in aluminum enrichment inside the particles. Therefore, the aluminum signal value of the small-sized aluminum-doped cobalt carbonate prepared by the current carbonate system is between 100 and 200, regardless of whether there are obvious flakes or honeycomb aluminum on the electron microscope, and the color difference is obvious, resulting in uneven aluminum distribution and affecting the properties of the material.

[0028] A first aspect of an embodiment of the present application provides a method for preparing aluminum-doped cobalt carbonate, comprising the following steps:

[0029] S01. Obtaining cobalt carbonate seed crystals;

[0030] S02. First, a soluble mixed salt solution containing cobalt salt and aluminum salt is added to the cobalt carbonate seed crystal, and then the soluble mixed salt solution containing cobalt salt and aluminum salt and ammonium bicarbonate feed liquid are added in a parallel flow manner for mixed reaction, and then grown and dried to prepare aluminum-doped cobalt carbonate.

[0031] A first aspect of an embodiment of the present application provides a method for preparing aluminum-doped cobalt carbonate. The method comprises first obtaining a cobalt carbonate seed crystal, and in the process of preparing the aluminum-doped cobalt carbonate, first adding a soluble mixed salt solution containing a cobalt salt and an aluminum salt, and then adding the cobalt salt solution to supplement the Co in the reaction system. 2+ , induced reaction system releases OH-, Al 3+ , CO 3 2- With Co 2+ Stable crystalline small-sized basic aluminum cobalt carbonate is generated, thereby preventing the generation of columnar objects; the preparation method is simple and easy to operate, the reaction conditions are mild, and it is green and environmentally friendly; and the aluminum element is evenly distributed in the prepared aluminum-doped cobalt carbonate material, and columnar impurities are completely eliminated, which is conducive to industrial production.

[0032] In step S01, cobalt carbonate seed crystals are obtained.

[0033] In some embodiments, the step of obtaining cobalt carbonate seeds includes: adding a soluble mixed salt solution containing cobalt salt and aluminum salt and an ammonium bicarbonate feed liquid to an ammonium bicarbonate bottom liquid in a parallel flow feeding manner for blending treatment to obtain cobalt carbonate seeds. In the preparation process of the seeds, a certain concentration of ammonium bicarbonate solution is used as the bottom liquid, and the cobalt carbonate nucleation rate in the early stage of synthesis is high, ensuring that the seed particle size is small; and by controlling the conditions of the blending treatment, the decomposition of the reactant ammonium bicarbonate is reduced to avoid the formation of columnar impurities. In the preparation process of cobalt carbonate seeds, it is not necessary to add a soluble mixed salt solution in advance. On the one hand, no columnar objects are produced; on the other hand, in order to control the morphology of cobalt carbonate seeds, it is necessary to simultaneously add a soluble mixed salt solution containing cobalt salt and aluminum salt and an ammonium bicarbonate feed liquid in a parallel flow feeding manner to obtain cobalt carbonate seeds with suitable morphology and size.

[0034] In some embodiments, the temperature of the first mixing reaction is 31-39° C., and the pH is 7.

[0035] In some embodiments, in a soluble mixed salt solution containing cobalt salt and aluminum salt, the mass ratio of aluminum element to cobalt element is 0.0055-0.0285:1. By controlling the mass ratio of aluminum element to cobalt element in the mixed salt solution, it is beneficial to control the amount of cobalt element and aluminum element added during the reaction to obtain an aluminum-doped cobalt carbonate material.

[0036] In some embodiments, the concentration of ammonium bicarbonate in the ammonium bicarbonate feed solution is 200-220 g / L. The provided ammonium bicarbonate feed solution is used to be added to the reaction system in a parallel flow manner together with a soluble mixed salt solution containing cobalt salt and aluminum salt for coprecipitation. The provided ammonium bicarbonate solution is used as a precipitant to obtain a product precipitate on the one hand, and is used to adjust the pH value in the entire reaction system to control the advancement of the reaction on the other hand. In some specific embodiments, the concentration of ammonium bicarbonate in the ammonium bicarbonate feed solution includes but is not limited to 200 g / L, 205 g / L, 210 g / L, 215 g / L, and 220 g / L.

[0037] In some embodiments, the concentration of ammonium bicarbonate in the ammonium bicarbonate base solution is 20 to 60 g / L. Using a certain concentration of ammonium bicarbonate solution as the base solution ensures that the cobalt carbonate nucleation rate in the initial stage of synthesis is high and the seed crystal particle size is small, which is conducive to the subsequent seed crystal growth. If the concentration of the provided ammonium bicarbonate base solution is too high, an instantaneous reaction will occur after the reaction solution is added, resulting in the formation of cobalt carbonate seed crystals with too small particle size, which is prone to agglomeration and is not conducive to particle dispersion; if the concentration of the provided ammonium bicarbonate base solution is too low, the cobalt carbonate seed crystals obtained by the reaction will have too large a particle size, which is not conducive to obtaining product particles with controllable morphology and particle size.

[0038] In some specific implementations, the concentration of ammonium bicarbonate in the ammonium bicarbonate base solution includes but is not limited to 20 g / L, 30 g / L, 40 g / L, 50 g / L, and 60 g / L.

[0039] In some embodiments, the temperature of the blending treatment is 31 to 39° C., and the pH is 7.0 to 8.5. In some specific embodiments, the temperature of the blending treatment is selected from 35° C. By controlling the reaction conditions at a relatively low temperature, the decomposition of ammonium bicarbonate in the early stage of synthesis can be reduced, and the formation of basic aluminum ammonium carbonate in the form of columns can be avoided.

[0040] In some embodiments, the particle size D of the cobalt carbonate seed is 50 The particle size of the cobalt carbonate seed is 1.5 to 2.0 μm; controlling the particle size of the seed crystal to be moderate is conducive to further controlling the growth of its particle size. 50 Including but not limited to 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, and 2.0μm.

[0041] In step S02, a soluble cobalt-aluminum mixed salt solution containing cobalt salt and aluminum salt is added to the cobalt carbonate seed crystal, and then the cobalt-aluminum mixed salt solution and ammonium bicarbonate feed liquid are added in a parallel flow manner for mixed reaction, and growth and drying are performed to prepare aluminum-doped cobalt carbonate.

[0042] Since the growth stage requires multiple cycles of feeding, standing, solid-liquid stratification, and extraction of supernatant, the reaction system will still automatically decompose ammonium bicarbonate when standing, extracting supernatant, and starting stirring, and the reaction system will contain OH-, NH 4 + and CO 3 2- At this stage, the amorphous aluminum carbonate is extremely unstable and hydrolyzes to release Al 3+ , these four ions transform into basic ammonium aluminum carbonate, and the reaction equation is shown in formula (1).

[0043] NH 4 + +2OH-+CO 3 2- +Al 3+ →NH 4 Al(OH) 2 CO 3 ↓.

[0044] In the present application, a cobalt salt solution is creatively added in advance during the reaction process of preparing aluminum-doped cobalt carbonate to supplement the Co 2+ , induced reaction system releases OH-, Al 3+ , CO 32- With Co 2+ Stable crystalline basic aluminum cobalt carbonate is generated. The induced reaction equation is shown in Formula (2).

[0045] 6Co 2+ +16OH-+CO 3 2- +2Al 3+ →Co 6 Al 2 (OH) 16 CO 3 ·4H 2 O↓.

[0046] In some embodiments, the preparation includes primary preparation and secondary preparation, wherein the primary preparation includes primary preparation to obtain primary growth particles of cobalt carbonate, and the secondary preparation includes adding a soluble mixed salt solution to the primary growth particles of cobalt carbonate, and then adding the soluble mixed salt solution and ammonium bicarbonate feed solution in a parallel flow manner for mixed reaction, and growing, to obtain aluminum-doped cobalt carbonate through secondary preparation.

[0047] In one specific embodiment, the process for preparing aluminum-doped cobalt carbonate comprises:

[0048] Adding a soluble mixed salt solution to the cobalt carbonate seed crystals, then adding the soluble mixed salt solution and ammonium bicarbonate feed solution in a cocurrent feeding manner for mixing reaction, and performing growth and drying treatment to prepare cobalt carbonate primary growth particles at one time;

[0049] Then, a soluble mixed salt solution is added to the primary growth particles of cobalt carbonate, and then the soluble mixed salt solution and ammonium bicarbonate feed liquid are added in a parallel flow manner for mixed reaction and growth, so as to obtain aluminum-doped cobalt carbonate for secondary preparation.

[0050] The first preparation is the seed growth stage. In the process of preparing the first growth particles of cobalt carbonate, a cobalt salt solution is added in advance to induce the OH released by the reaction system. - 、Al 3+ , CO 3 2- With Co 2+ On the one hand, a stable crystalline basic aluminum cobalt carbonate is generated; on the other hand, a lower temperature is used at the same time to further reduce the decomposition of ammonium bicarbonate in the growth stage; the growth conditions of the precipitation of basic aluminum ammonium carbonate are controlled from two aspects, the generation of basic aluminum ammonium carbonate is controlled from the source, and the technical problem of the precipitation of aluminum-containing columns in the synthesis process is solved.

[0051] In some embodiments, the reaction temperature for one preparation is 26-34°C. In some specific embodiments, the reaction temperature for one preparation is 30°C.

[0052] In some embodiments, in the step of adding a soluble mixed salt solution containing a cobalt salt and an aluminum salt to the cobalt carbonate seed crystals, the pH of the mixed solution is controlled to be adjusted from 7.6 to 7.3. After the soluble mixed salt solution containing a cobalt salt and an aluminum salt is added, the solution becomes acidic due to the presence of cobalt ions. Therefore, by controlling the pH of the mixed solution to be adjusted from 7.6 to 7.3, the concentration of the added cobalt ions can be controlled.

[0053] In some specific embodiments, in the step of adding the mixed salt solution to the cobalt carbonate seed crystals, the time for adding the mixed salt solution is controlled to be 5 to 10 minutes. By controlling the time for adding the mixed salt solution, the concentration of the added cobalt ions can be controlled so that the pH of the mixed solution is adjusted from 7.6 to 7.3.

[0054] In some embodiments, the concentration of cobalt element in the provided cobalt salt solution is 80-120 g / L; the cobalt salt solution is prepared separately and mainly used to pre-replenish the cobalt ions in the reaction system during the seed growth stage, and by pre-increasing the concentration of cobalt ions in the system, the OH- and Al-ions released by the reaction system are induced. 3+ , CO 3 2- With Co 2+ Stable crystalline basic aluminum cobalt carbonate is generated, thereby blocking the formation of columns during the reaction process, so that the obtained aluminum-doped cobalt carbonate material does not contain aluminum columns.

[0055] In some embodiments, the cobalt salt is selected from at least one of cobalt sulfate, cobalt chloride, and cobalt nitrate.

[0056] In some specific embodiments, the concentration of cobalt element in the provided cobalt salt solution includes but is not limited to 80 g / L, 85 g / L, 90 g / L, 95 g / L, 100 g / L, 105 g / L, 110 g / L, 115 g / L, and 120 g / L.

[0057] In some embodiments, the particle size D of the primary growth particle of cobalt carbonate is 50 In some specific embodiments, the particle size D of the primary growth particles of cobalt carbonate is 2.5 to 3.0 μm. 50 Including but not limited to 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm, 3.0 μm. The specific particle size of the primary growth particles of cobalt carbonate can be adjusted according to specific needs.

[0058] The secondary preparation is the consolidation growth stage. In the consolidation growth stage, since the soluble mixed salt solution and ammonium bicarbonate feed solution still need to be added in parallel, a mixed salt solution containing cobalt salt is added in advance to supplement the Co in the reaction system. 2+ , induced reaction system releases OH - 、Al3+ , CO 3 2- With Co 2+ Generate stable crystalline basic aluminum cobalt carbonate; and control the conditions of secondary preparation to ensure that the product with controllable morphology and particle size, compact particles and stable properties is obtained.

[0059] In some embodiments, the reaction temperature of the secondary preparation is 34-42° C. The reaction temperature of the secondary preparation is slightly higher than that of the primary preparation, in order to increase the crystallinity of the outer layer of the material, make the particles more tightly connected, and prevent aluminum powder from being easily generated on the surface; at the same time, since the aluminum element is amorphous inside, by slightly increasing the temperature, the amorphous aluminum is further controlled to be transformed into a stable structure, ensuring that the properties of the obtained particles are stable.

[0060] In some embodiments, in the step of adding a soluble mixed salt solution to the cobalt carbonate primary growth particles, the pH of the mixed solution is controlled to be adjusted from 7.6 to 7.3. After the soluble mixed salt solution containing cobalt salt and aluminum salt is added, the solution will be acidic due to the cobalt ions contained in the solution. Therefore, by controlling the pH of the mixed solution to be adjusted from 7.6 to 7.3, the concentration of the added cobalt ions can be controlled.

[0061] In some embodiments, in the step of first adding the mixed salt solution to the cobalt carbonate primary growth particles, the time for adding the mixed salt solution is controlled to be 5 to 10 minutes. By controlling the time for adding the mixed salt solution, the concentration of the added cobalt ions can be controlled so that the pH of the mixed solution is adjusted from 7.6 to 7.3.

[0062] In some embodiments, the particle size D50 of aluminum-doped cobalt carbonate is 3.9-6 μm. In some specific embodiments, the particle size D50 of aluminum-doped cobalt carbonate includes but is not limited to 3.9 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, and 6 μm. The specific particle size of aluminum-doped cobalt carbonate can be adjusted according to specific needs.

[0063] In some embodiments, the growth includes multiple cycles of intermittent growth or continuous growth using a reactor with a built-in concentrator.

[0064] In some embodiments, the process of performing multiple cycles of intermittent growth includes: after repeated cycles of adding a mixed salt solution, adding a soluble mixed salt solution and an ammonium bicarbonate feed solution in a parallel flow manner for reaction, performing static treatment, solid-liquid stratification, extracting the supernatant, and starting a new round of feeding steps; repeating the cycle 3 to 4 times for intermittent growth, so that the cobalt carbonate seed crystals grow to 2.5 to 3.0 μm through multiple cycles of intermittent growth.

[0065] In some embodiments, multiple cycles of intermittent growth are performed using a conventional reactor, in which the supernatant in the reactor is pumped out by a pump, and then a new round of feeding is started to achieve intermittent growth.

[0066] In some embodiments, continuous growth is performed by using a reactor with a built-in concentrator. During the first feeding process of the reaction, a mixed salt solution containing cobalt salt is added in advance, and then a soluble mixed salt solution and ammonium bicarbonate feed liquid are added in a parallel feeding manner for reaction; further, the reactor uses a built-in concentrator to extract excess solution in the reactor to ensure that the liquid level in the reactor is maintained in a stable range, thereby achieving continuous growth. At the same time, the process of standing, solid-liquid stratification, and extracting the supernatant can be omitted, further reducing the release of OH by the reaction system. - , and realize continuous production.

[0067] In some embodiments, washing treatment is first performed and then drying treatment is performed; the specific steps include: the grown aluminum-doped cobalt carbonate slurry is pumped into a centrifuge, washed with 10-30°C water for 30 minutes, centrifugally dehydrated and then flash dried to obtain dry aluminum-doped small-particle cobalt carbonate.

[0068] A second aspect of an embodiment of the present application provides an aluminum-doped cobalt carbonate, which is prepared by a method for preparing aluminum-doped cobalt carbonate.

[0069] The aluminum-doped cobalt carbonate provided in the second aspect of the embodiment of the present application is prepared by the above-mentioned preparation method. Therefore, the obtained aluminum-doped cobalt carbonate is stable crystalline small-sized particles with controllable morphology and particle size, uniform distribution of aluminum elements, and no aluminum columns will precipitate in the material, which is conducive to wide application.

[0070] The following describes the invention in conjunction with specific embodiments.

[0071] Example 1

[0072] Aluminum-doped cobalt carbonate and preparation method thereof

[0073] The preparation method comprises the following steps:

[0074] (1) obtaining cobalt carbonate seed crystals;

[0075] Prepare the solution: weigh soluble aluminum sulfate and cobalt sulfate and add them into pure water to prepare a cobalt-aluminum mixed salt solution doped with aluminum element, with a cobalt salt concentration of 80 g / L and a mass ratio of aluminum element to cobalt element of 0.0055; prepare an ammonium bicarbonate solution with a concentration of 200 g / L;

[0076] Seed preparation: pure water and ammonium bicarbonate solution are injected into the reactor as the bottom liquid, the concentration of the bottom liquid ammonium bicarbonate is 25g / L, stirring is started, and the cobalt aluminum mixed salt solution and the ammonium bicarbonate solution are added in a parallel feeding manner. The reaction temperature is set to 31°C, the pH value is 7.0-8.5, and the reaction is carried out until cobalt carbonate seeds with a particle size D50 of 1.5μm are obtained;

[0077] (2) adding a soluble mixed salt solution containing cobalt salt and aluminum salt to the cobalt carbonate seed crystals, and then adding the soluble mixed salt solution containing cobalt salt and aluminum salt and ammonium bicarbonate feed solution in a cocurrent feeding manner for mixed reaction, and performing growth and drying treatment to prepare aluminum-doped cobalt carbonate.

[0078] The preparation includes primary preparation and secondary preparation. The primary preparation is: continue to add mixed metal salt solution and ammonium bicarbonate solution to the cobalt carbonate seed crystal, the reaction temperature is set to 26°C, and the pH value is 6.5-7.5. Intermittent growth is carried out through a cycle of adding materials, standing, solid-liquid stratification, and extracting the supernatant. After extracting the supernatant, start stirring, add cobalt liquid in advance for 5 minutes, and then turn on the ammonium bicarbonate solution feed pump. Continue to add mixed metal salt solution and ammonium bicarbonate solution in parallel to grow the cobalt carbonate primary growth particles to 2.6μm;

[0079] The secondary preparation is as follows: Continue to add the mixed metal salt solution and ammonium bicarbonate solution to the primary growth particles of cobalt carbonate, set the reaction temperature to 34°C, and the pH value to 6.5-7.5. Intermittent growth is carried out through a cycle of adding materials, standing, solid-liquid stratification, and extracting the supernatant. After extracting the supernatant, start stirring, pre-add cobalt solution for 5 minutes, and then turn on the ammonium bicarbonate solution feed pump. Continue to add the mixed metal salt solution and ammonium bicarbonate solution in parallel to grow the cobalt carbonate particles to 3.9μm;

[0080] Washing and drying: The doped cobalt carbonate slurry is passed into a centrifuge and washed with 10°C water for 30 minutes. After centrifugal dehydration, it is dried by a flash evaporator to obtain dry aluminum-doped small-particle cobalt carbonate.

[0081] Example 2

[0082] Aluminum-doped cobalt carbonate and preparation method thereof

[0083] The preparation method comprises the following steps:

[0084] (1) obtaining cobalt carbonate seed crystals;

[0085] Prepare the solution: weigh soluble aluminum sulfate and cobalt sulfate and add them into pure water to prepare a cobalt-aluminum mixed salt solution doped with aluminum element, with a cobalt salt concentration of 80 g / L and a mass ratio of aluminum element to cobalt element of 0.0120; prepare an ammonium bicarbonate solution with a concentration of 200 g / L;

[0086] Seed preparation: pure water and ammonium bicarbonate solution are injected into the reactor as the bottom liquid, the concentration of the bottom liquid ammonium bicarbonate is 25g / L, stirring is started, and the cobalt aluminum mixed salt solution and the ammonium bicarbonate solution are added in a parallel feeding manner. The reaction temperature is set to 35°C, the pH value is 7.0-8.5, and the reaction is carried out until the cobalt carbonate seed with a particle size D50 of 1.8μm is obtained;

[0087] (2) adding a soluble mixed salt solution containing a cobalt salt and an aluminum salt to the cobalt carbonate seed crystals, and then adding the soluble mixed salt solution containing a cobalt salt and an aluminum salt and an ammonium bicarbonate feed solution in a cocurrent feeding manner for a mixing reaction, and performing growth and drying treatment to prepare aluminum-doped cobalt carbonate;

[0088] Among them, the preparation includes primary preparation and secondary preparation; the primary preparation is to continue to add mixed metal salt solution and ammonium bicarbonate solution to the cobalt carbonate seed crystals, the reaction temperature is set to 30°C, and the pH value is 6.5-7.5. Intermittent growth is carried out through a cycle of adding materials, standing, solid-liquid stratification, and extracting the supernatant. After extracting the supernatant, start stirring, add cobalt liquid in advance for 10 minutes, and then turn on the ammonium bicarbonate solution feeding pump. Continue to add mixed metal salt solution and ammonium bicarbonate solution in a parallel flow feeding method to grow the cobalt carbonate primary growth particles to 2.7μm;

[0089] The secondary preparation is to continue to add mixed metal salt solution and ammonium bicarbonate solution to the primary growth particles of cobalt carbonate. The reaction temperature is set to 38°C and the pH value is 6.5-7.5. Intermittent growth is carried out through a cycle of adding materials, standing, solid-liquid stratification, and extracting the supernatant. After extracting the supernatant, start stirring, add cobalt solution in advance for 5 minutes, and then turn on the ammonium bicarbonate solution feed pump. Continue to add mixed metal salt solution and ammonium bicarbonate solution in parallel to grow the cobalt carbonate particles to 3.9μm;

[0090] Washing and drying: The doped cobalt carbonate slurry is passed into a centrifuge, washed with 20°C water for 20 minutes, centrifuged and dehydrated, and then dried by a flash evaporator to obtain dry aluminum-doped small-particle cobalt carbonate.

[0091] Example 3

[0092] Aluminum-doped cobalt carbonate and preparation method thereof

[0093] The preparation method comprises the following steps:

[0094] (1) obtaining cobalt carbonate seed crystals;

[0095] Prepare the solution: weigh soluble aluminum chloride and cobalt chloride and add them into pure water to prepare a cobalt-aluminum mixed salt solution doped with aluminum, with a cobalt salt concentration of 80 g / L and a mass ratio of aluminum to cobalt of 0.0285; prepare an ammonium bicarbonate solution with a concentration of 200 g / L;

[0096] Seed preparation: pure water and ammonium bicarbonate solution are injected into a reactor with a built-in concentrator as the bottom liquid, the concentration of ammonium bicarbonate in the bottom liquid is 25 g / L, stirring is started, and the cobalt aluminum mixed salt solution and the ammonium bicarbonate solution are added in a parallel feeding manner. The reaction temperature is set to 39° C., the pH value is 7.0-8.5, and the reaction is carried out until cobalt carbonate seeds with a particle size D50 of 2.0 μm are obtained;

[0097] (2) adding a soluble mixed salt solution containing a cobalt salt and an aluminum salt to the cobalt carbonate seed crystals, and then adding the soluble mixed salt solution containing a cobalt salt and an aluminum salt and an ammonium bicarbonate feed solution in a cocurrent feeding manner for a mixing reaction, and performing growth and drying treatment to prepare aluminum-doped cobalt carbonate;

[0098] The preparation includes primary preparation and secondary preparation. The primary preparation includes adding cobalt liquid to the cobalt carbonate seed crystals for 10 minutes, and then adding a mixed metal salt solution and an ammonium bicarbonate solution. The reaction temperature is set to 34°C and the pH value is 6.5 to 7.5. The concentration device is turned on for continuous feeding growth, so that the primary growth particles of cobalt carbonate grow to 2.7 μm.

[0099] The secondary preparation is to add cobalt solution to the primary growth particles of cobalt carbonate for 10 minutes, and then continue to add mixed metal salt solution and ammonium bicarbonate solution. The reaction temperature is set to 42°C and the pH value is 6.5-7.5. The cobalt carbonate particles grow to 3.9 μm by opening the concentration device for continuous feeding growth.

[0100] Washing and drying: The doped cobalt carbonate slurry is passed into a centrifuge and washed with 30°C water for 20 minutes. After centrifugal dehydration, it is dried by a flash evaporator to obtain dry aluminum-doped small-particle cobalt carbonate.

[0101] Comparative Example 1

[0102] Aluminum-doped cobalt carbonate and preparation method thereof

[0103] The preparation method comprises the following steps:

[0104] (1) obtaining cobalt carbonate seed crystals;

[0105] Prepare the solution: weigh soluble aluminum sulfate and cobalt sulfate and add them into pure water to prepare a cobalt-aluminum mixed salt solution doped with aluminum element, with a cobalt salt concentration of 80 g / L and a mass ratio of aluminum element to cobalt element of 0.0120; prepare an ammonium bicarbonate solution with a concentration of 200 g / L;

[0106] Seed preparation: pure water and ammonium bicarbonate solution are injected into the reactor as the bottom liquid, the concentration of the bottom liquid ammonium bicarbonate is 25g / L, stirring is started, and the cobalt aluminum mixed salt solution and the ammonium bicarbonate solution are added in a parallel feeding manner. The reaction temperature is set to 30°C, the pH value is 7.0-8.5, and the reaction is carried out until cobalt carbonate seeds with a particle size D50 of 1.8μm are obtained;

[0107] (2) adding a soluble mixed salt solution containing cobalt salt and aluminum salt and an ammonium bicarbonate feed solution in a cocurrent feeding manner for mixed reaction, and performing growth and drying treatment to prepare aluminum-doped cobalt carbonate;

[0108] Specifically include:

[0109] Growth stage: Continue to add mixed metal salt solution and ammonium bicarbonate solution, set the reaction temperature to 38°C, and the pH value to 6.5-7.5. Perform intermittent growth by a cycle of adding materials, standing, solid-liquid stratification, and extracting the supernatant. After extracting the supernatant, start stirring, continue to add mixed metal salt solution and ammonium bicarbonate solution in parallel, so that the cobalt carbonate particles grow to 2.7μm after three growths;

[0110] Consolidation stage: Continue to add mixed metal salt solution and ammonium bicarbonate solution, set the reaction temperature to 38°C, and the pH value to 6.5-7.5. Perform intermittent growth through a cycle of adding materials, standing, solid-liquid stratification, and extracting the supernatant. After extracting the supernatant, start stirring, and then start the mixed metal salt solution and ammonium bicarbonate solution feed pumps at the same time. Continue to add mixed metal salt solution and ammonium bicarbonate solution in parallel, so that the cobalt carbonate particles grow to 3.9μm after 8 growths;

[0111] Washing and drying: The doped cobalt carbonate slurry is passed into a centrifuge, washed with 40°C water for 20 minutes, centrifuged and dehydrated, and then dried by a flash evaporator to obtain dry aluminum-doped small-particle cobalt carbonate.

[0112] Comparative Example 2

[0113] Aluminum-doped cobalt carbonate and preparation method thereof

[0114] The preparation method comprises the following steps:

[0115] (1) obtaining cobalt carbonate seed crystals;

[0116] Prepare the solution: weigh soluble aluminum sulfate and cobalt sulfate and add them into pure water to prepare a cobalt-aluminum mixed salt solution doped with aluminum element, with a cobalt salt concentration of 80 g / L and a mass ratio of aluminum element to cobalt element of 0.0120; prepare an ammonium bicarbonate solution with a concentration of 200 g / L;

[0117] Seed preparation: pure water and ammonium bicarbonate solution are injected into the reactor as the bottom liquid, the concentration of the bottom liquid ammonium bicarbonate is 25g / L, stirring is started, and the cobalt aluminum mixed salt solution and the ammonium bicarbonate solution are added in a parallel feeding manner. The reaction temperature is set to 40°C, the pH value is 7.0-8.5, and the reaction is carried out until the cobalt carbonate seed with a particle size D50 of 1.8μm is obtained;

[0118] (2) adding a soluble mixed salt solution containing cobalt salt and aluminum salt and an ammonium bicarbonate feed solution in a cocurrent feeding manner for mixed reaction, and performing growth and drying treatment to prepare aluminum-doped cobalt carbonate;

[0119] Specifically include:

[0120] Growth stage: Continue to add mixed metal salt solution and ammonium bicarbonate solution, set the reaction temperature to 38°C, and the pH value to 7.5-8.0. Perform intermittent growth by a cycle of adding materials, standing, solid-liquid stratification, and extracting the supernatant. After extracting the supernatant, start stirring, continue to add mixed metal salt solution and ammonium bicarbonate solution in parallel, and grow the cobalt carbonate primary growth particles to 2.7μm.

[0121] Consolidation stage: Continue to add mixed metal salt solution and ammonium bicarbonate solution, set the reaction temperature to 38°C, and the pH value to 7.5-8.0. Intermittent growth is carried out by a cycle of adding materials, standing, solid-liquid stratification, and extracting the supernatant. After extracting the supernatant, start stirring, and then start the mixed metal salt solution and ammonium bicarbonate solution feed pumps at the same time. Continue to add mixed metal salt solution and ammonium bicarbonate solution in parallel to grow the cobalt carbonate particles to 3.9μm.

[0122] Washing and drying: The doped cobalt carbonate slurry is passed into a centrifuge and washed with 80°C water for 20 minutes. After centrifugal dehydration, it is dried in an oven to obtain dry aluminum-doped cobalt carbonate with small particle size.

[0123] Performance Testing

[0124] (1) The primary growth particles of cobalt carbonate obtained in Examples 1 to 3 and Comparative Examples 1 to 2 and the product of aluminum-doped cobalt carbonate were analyzed by electron microscope.

[0125] (2) Analyze the aluminum signal values ​​of the aluminum-doped cobalt carbonate product obtained in Example 3 and the aluminum-containing columnar product obtained in Comparative Example 1.

[0126] Results Analysis

[0127] (1) The primary growth particles of cobalt carbonate obtained in Examples 1 to 3 and Comparative Examples 1 to 2 and the product of aluminum-doped cobalt carbonate were analyzed by electron microscope, as follows:

[0128] like Figure 1 As shown, Figure 1 A is a SEM image of the primary growth particles of cobalt carbonate obtained in Example 1, and the electron microscope shows that there are no columns; Figure 1 B is the SEM picture of the product doped with cobalt aluminum carbonate obtained in Example 1, and the electron microscope shows that there are no columns.

[0129] like Figure 2 As shown, Figure 2 A is a SEM image of the primary growth particles of cobalt carbonate obtained in Example 2, and the electron microscope shows that there are no columns; Figure 2 B is the SEM picture of the product doped with cobalt aluminum carbonate obtained in Example 2, and the electron microscope shows that there are no columns.

[0130] like Figure 3 As shown, Figure 3 A is a SEM image of the primary growth particles of cobalt carbonate obtained in Example 3, and the electron microscope shows that there are no columns; Figure 3 B is the SEM image of the aluminum-doped cobalt carbonate obtained in Example 3. The electron microscope shows that there are no columns. In addition, the electron probe EPMA analysis of the particle cross section shows that the maximum aluminum signal value is 46, there is no color difference, and the aluminum is evenly distributed.

[0131] like Figure 4 As shown, Figure 4 A is a SEM image of the primary growth particles of cobalt carbonate obtained in Example 1, and the electron microscope shows that there are columns; Figure 4 B is a SEM image of the product obtained in Example 1, which shows that there are columns. In addition, the electron probe EPMA analysis of the particle cross section shows that the maximum aluminum signal value is 119, the color difference is large, and the aluminum distribution is uneven.

[0132] like Figure 5 As shown, Figure 5 A is a SEM image of the primary growth particles of cobalt carbonate obtained in Example 2, and the electron microscope shows that there are columns; Figure 5 B is the SEM picture of the product obtained in Example 2 doped with cobalt aluminum carbonate, and the electron microscope shows columnar objects.

[0133] (2) The signal values ​​of the cobalt aluminate obtained in Example 3 and the cobalt aluminate obtained in Comparative Example 1 were further analyzed using an electron microprobe analyzer (EPMA). Figure 6 As shown, Figure 6 A is the aluminum signal value of the product obtained in Comparative Example 1, which is 119. Figure 6 B is the aluminum signal value of the cobalt aluminum carbonate-doped product obtained in Example 3, which is 46. It can be seen that the uniformity of aluminum in the product of Example 3 is greatly improved after the columns are eliminated, and the aluminum signal value containing the columns is reduced from 119 to 46, and there is no color difference in the aluminum distribution.

[0134] In summary, the preparation method of aluminum-doped cobalt carbonate provided by the present application first obtains cobalt carbonate seeds, and in the process of preparing aluminum-doped cobalt carbonate, pre-adds a mixed salt solution, wherein the mixed salt solution includes a cobalt salt solution, which can replenish the Co2+ of the reaction system in advance, induce the OH-, Al3+, CO32- released by the reaction system and Co2+ to generate stable crystalline small-sized basic aluminum cobalt carbonate, thereby preventing the formation of columns; the preparation method is simple and easy to operate, has mild reaction conditions, is green and environmentally friendly, and the prepared aluminum-doped cobalt carbonate material has a uniform distribution of aluminum elements, completely eliminates columnar impurities, and is conducive to industrial production.

[0135] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing aluminum-doped cobalt carbonate, characterized in that: The steps include: obtaining cobalt carbonate seed crystals; A soluble mixed salt solution containing cobalt salt and aluminum salt is first added to the cobalt carbonate seed crystal, and then the soluble mixed salt solution containing cobalt salt and aluminum salt and ammonium bicarbonate feed liquid are added in a parallel flow manner for mixed reaction, and growth and drying are performed to prepare aluminum-doped cobalt carbonate.

2. The method for preparing aluminum-doped cobalt carbonate according to claim 1, characterized in that: The preparation includes primary preparation and secondary preparation, wherein the primary preparation includes primary preparation to obtain primary growth particles of cobalt carbonate, and the secondary preparation includes adding a soluble mixed salt solution to the primary growth particles of cobalt carbonate, and then adding the soluble mixed salt solution and ammonium bicarbonate feed liquid in a parallel flow manner for mixed reaction and growth, and the secondary preparation obtains aluminum-doped cobalt carbonate.

3. The method for preparing aluminum-doped cobalt carbonate according to claim 2, characterized in that: The reaction temperature of the primary preparation is 26-34° C.; and / or, The reaction temperature of the secondary preparation is 34-42°C.

4. The method for preparing aluminum-doped cobalt carbonate according to claim 1, characterized in that: In the step of adding a soluble mixed salt solution containing a cobalt salt and an aluminum salt to the cobalt carbonate seed crystals, the pH of the reaction solution is controlled to be adjusted from 7.6 to 7.

3.

5. The method for preparing aluminum-doped cobalt carbonate according to claim 2, characterized in that: In the step of adding the soluble mixed salt solution to the cobalt carbonate primary growth particles, the pH of the reaction solution is controlled to be adjusted from 7.6 to 7.

3.

6. The method for preparing aluminum-doped cobalt carbonate according to claim 1, characterized in that: The growth includes multiple cycles of intermittent growth or continuous growth using a reactor with a built-in concentrator.

7. The method for preparing aluminum-doped cobalt carbonate according to claim 1, characterized in that: The step of obtaining cobalt carbonate seed crystals comprises: adding a soluble mixed salt solution containing cobalt salt and aluminum salt and an ammonium bicarbonate feed liquid into an ammonium bicarbonate bottom liquid in a cocurrent feeding manner for blending treatment to obtain cobalt carbonate seed crystals; wherein the blending treatment temperature is 31-39° C. and the pH is 7.0-8.

5.

8. The method for preparing aluminum-doped cobalt carbonate according to claim 1, characterized in that: In the soluble mixed salt solution containing cobalt salt and aluminum salt, the mass ratio of aluminum element to cobalt element is 0.0055-0.0285:1; and / or, In the ammonium bicarbonate feed solution, the concentration of ammonium bicarbonate is 200-220 g / L.

9. The method for preparing aluminum-doped cobalt carbonate according to claim 2, characterized in that: The particle size D of the cobalt carbonate seed 50 1.5 to 2.0 μm; and / or, The particle size D of the cobalt carbonate primary growth particle 50 2.5 to 3.0 μm; and / or The particle size D of the aluminum-doped cobalt carbonate 50 3.9~6μm.

10. An aluminum-doped cobalt carbonate, characterized in that: The aluminum-doped cobalt carbonate is prepared by the method for preparing aluminum-doped cobalt carbonate according to any one of claims 1 to 9.

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