A cobalt oxyhydroxide, a preparation method and application thereof

Abstract

The application provides a kind of cobalt oxyhydroxide and its preparation method and application, the preparation method of the cobalt oxyhydroxide includes, bivalent cobalt solution and liquid alkali are passed into the microchannel reactor with bottom water and carry out precipitation reaction;Collect slurry, carry out post-treatment, obtain cobalt oxyhydroxide;Wherein, the bivalent cobalt solution also contains oxidizing agent, the pH of the bottom water is 12.0-14.0, when the precipitation reaction, still continuously air with flow 1.0-2.5kg / h is passed into the microchannel reactor.The preparation method of the cobalt oxyhydroxide provided by the application, using microchannel reactor to prepare cobalt oxyhydroxide, realize millisecond level mixing and second level residence time control, avoid local overheating and byproduct generation, intrinsic safety is high, operation is flexible, can be modularized and parallel amplification;In addition, the application optimizes the composition of reaction system, and by regulating the flow of air, different morphologies and sizes of cobalt oxyhydroxide are prepared, which can adapt to different downstream application requirements.

Description

Technical Field

[0001] This invention relates to the field of cobalt compound technology, specifically to a cobalt hydroxyoxide, its preparation method, and its applications. Background Technology

[0002] With the rapid development of portable electronic devices and new energy vehicles, the market demand for high-energy-density, long-cycle-life lithium-ion batteries is becoming increasingly urgent. Ternary cathode materials (such as NCM and NCA) have become the mainstream choice due to their high specific capacity. However, with the increase of nickel content, the materials face problems such as excessive surface residual alkali (LiOH, Li2CO3), poor structural stability, and cycle performance degradation. Nano-cobalt hydroxyoxide (CoOOH), as an effective functional additive, can react with surface residual alkali during the calcination synthesis of ternary cathode materials to form a stable coating layer, thereby reducing interfacial side reactions and improving the cycle stability and rate performance of the material. In addition, cobalt hydroxyoxide, due to its unique layered structure and electrochemical activity, also shows great potential in fields such as the oxygen evolution reaction (OER) electrocatalysis. Therefore, developing a process for the efficient and controllable preparation of high-performance nano-cobalt hydroxyoxide has significant industrial value.

[0003] Currently, the industrial preparation of nano-cobalt hydroxyl primarily employs the traditional batch reactor process. This process typically involves co-precipitating or oxidizing a cobalt salt solution with an alkaline solution and an oxidant in a stirred tank. While this method is technically mature, it suffers from several inherent drawbacks: First, the mass and heat transfer efficiency of the batch reactor is limited, especially during the initial feeding and reaction stages. Local supersaturation is difficult to control precisely, leading to uneven particle nucleation and growth, resulting in a wide particle size distribution and irregular morphology, which fails to meet the stringent requirements for uniform particle size in high-end cathode materials. Second, the highly exothermic oxidation reaction easily creates localized hot spots within the reactor, triggering secondary nucleation or particle agglomeration, affecting product performance and posing safety hazards. Finally, the traditional batch process exhibits significant scale-up effects. From small-scale trials to pilot-scale production and then to mass production, considerable time and resources are required for process parameter optimization, severely hindering rapid market response for new products.

[0004] To overcome the limitations of traditional batch processes, microchannel reactor technology, with its superior mass and heat transfer properties, offers a novel technological pathway for the continuous and controllable synthesis of nanomaterials. Microchannel reactors possess micron-scale channel dimensions, resulting in an extremely large specific surface area (reaching 5000-50000 m²). 2 / m 3This significantly shortens the diffusion distance between reactants, improving mass and heat transfer efficiency by 1-3 orders of magnitude compared to traditional reactors. This highly efficient mass transfer characteristic enables reactants to achieve uniform mixing at the molecular level within milliseconds, creating ideal conditions for rapid and uniform nucleation of nanoparticles, which is beneficial for preparing high-quality nanomaterials with smaller particle sizes and narrower particle distributions. Patent CN106549153A discloses a hollow hexagonal cobalt hydroxyl oxide nanomaterial and its preparation method. This method involves continuously feeding a divalent cobalt salt solution and an ammonia solution into a microchannel reactor at the same flow rate for precipitation. The slurry is then heated and aged in a batch reactor before being further aged by introducing a strong alkaline solution to obtain the hollow hexagonal cobalt hydroxyl oxide nanomaterial. This method has advantages such as a semi-continuous reaction process, simple process flow, and mild reaction conditions, but the aging time is relatively long, and the hollow structure of the product limits its effectiveness in battery materials.

[0005] Therefore, it is necessary to develop a more efficient method for preparing cobalt hydroxyl oxide with better product quality based on microchannel reactors. Summary of the Invention

[0006] To overcome the problems existing in the prior art, the present invention provides a method for preparing cobalt hydroxyoxide, comprising, A divalent cobalt solution and liquid alkali are passed into a microchannel reactor containing bottom water to carry out a precipitation reaction. Collect the slurry and perform post-processing to obtain cobalt hydroxyoxide; The divalent cobalt solution also contains an oxidant, the pH of the bottom water is 12.0-14.0, and air is continuously introduced into the microchannel reactor at a flow rate of 1.0-2.5 kg / h during the precipitation reaction.

[0007] Furthermore, the concentration of cobalt in the divalent cobalt solution is 120-140 g / L, and the concentration of the oxidant is 6-8 kg / Mt.

[0008] Furthermore, the mass concentration of the liquid alkali is 30%-40%.

[0009] Furthermore, the flow rate of the divalent cobalt solution is 5.0-20.0 g / min.

[0010] Furthermore, the flow rate ratio of the liquid alkali to the divalent cobalt solution is 0.4-0.6:1.

[0011] Furthermore, the slurry is collected by real-time monitoring of the particle size of the material at the outlet. Collection begins when the D50 of the material is ≤0.5μm.

[0012] Furthermore, the post-processing includes demagnetization, washing, and drying; The washing process reduces the concentration of impurity ions to below 20 ppm.

[0013] Furthermore, the volume of the bottom water is the same as the volume of the microchannel reactor, and the volume of the bottom water is 1.0-2.0L.

[0014] The present invention also provides cobalt hydroxyoxide, which is obtained by the above preparation method.

[0015] The present invention also provides the application of the above-mentioned cobalt hydroxyoxide in lithium batteries, catalysts, and functional fillers.

[0016] Compared with the prior art, the beneficial effects of the present invention include: The method for preparing cobalt hydroxyl oxide provided by this invention uses a microchannel reactor to prepare cobalt hydroxyl oxide, achieving millisecond-level mixing and second-level residence time control, avoiding local overheating and by-product generation; it adopts a continuous flow mode, with no scale-up effect, and can achieve industrial production through "quantitative scale-up"; it has a small liquid holdup, high intrinsic safety, flexible operation, and can be modularly scaled up in parallel.

[0017] This invention optimizes the composition of the reaction system and, by controlling the air flow rate, prepares cobalt hydroxyl oxide with different morphologies and sizes, which can be adapted to different downstream application requirements.

[0018] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0020] Figures 1-4 The following are scanning electron microscope images of cobalt hydroxyoxide prepared in Example 1 at different magnifications; Figures 5-8 The following are scanning electron microscope images of cobalt hydroxyoxide prepared in Example 2 at different magnifications; Figures 9-12 The following are scanning electron microscope images of cobalt hydroxyoxide prepared in Example 3 at different magnifications; Figures 13-16 The following are scanning electron microscope images of cobalt hydroxyoxide prepared in Comparative Example 1 at different magnifications; Figure 17A scanning electron microscope image of cobalt hydroxyoxide prepared in Comparative Example 2 is shown. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the invention, are intended to cover non-exclusive inclusion.

[0023] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0024] Microchannel reactors, with their revolutionary advantages in "three transfers and one reaction" (mass transfer, heat transfer, momentum transfer, and reaction process), have opened up new, continuous, intelligent, and green pathways for the preparation of high-performance nanomaterials. However, research on the preparation of cobalt hydroxyl oxide using microchannel reactors is currently limited, and the preparation of uniform cobalt hydroxyl oxide based on microchannel reactors remains a challenge.

[0025] Therefore, the design concept of this invention is to add a small amount of oxidant to the divalent cobalt solution. The content of the oxidant is insufficient to completely oxidize the divalent cobalt during the precipitation reaction. Air is introduced during the reaction in the microchannel reactor to oxidize and control the morphology of the intermediate, thereby obtaining cobalt hydroxyl oxide with uniform morphology. The morphology and particle size of the cobalt hydroxyl oxide can be effectively controlled according to the air flow rate.

[0026] This invention provides a method for preparing cobalt hydroxyoxide, comprising, A divalent cobalt solution and liquid alkali are passed into a microchannel reactor containing bottom water to carry out a precipitation reaction. Collect the slurry and perform post-processing to obtain cobalt hydroxyoxide; The divalent cobalt solution also contains an oxidant, the pH of the bottom water is 12.0-14.0, and air is continuously introduced into the microchannel reactor at a flow rate of 1.0-2.5 kg / h during the precipitation reaction.

[0027] It should be noted that the cobalt source in the divalent cobalt solution is not strictly limited, and can be, for example, at least one of cobalt chloride hexahydrate, cobalt sulfate heptahydrate, cobalt acetate dihydrate, and cobalt acetate tetrahydrate. The liquid alkali is a solution of an inorganic strong base, which can be at least one of potassium hydroxide and sodium hydroxide. The solvent for the inorganic strong base and the cobalt source is not strictly limited, and can be, for example, at least one of water, ethanol, isopropanol, and acetone, preferably water.

[0028] In some preferred embodiments, the concentration of cobalt in the divalent cobalt solution is 120-140 g / L, and the concentration of the oxidant is 6-8 kg / Mt. The oxidant is a commonly used oxidant in the art, and can be, for example, at least one of hydrogen peroxide, sodium hypochlorite, potassium hypochlorite, etc., preferably hydrogen peroxide, at a commercially available concentration.

[0029] In some preferred embodiments, the mass concentration of the liquid alkali is 30%-40%.

[0030] In some preferred embodiments, the flow rate of the divalent cobalt solution is 5.0-20.0 g / min.

[0031] In some preferred embodiments, the flow rate ratio of the liquid alkali to the divalent cobalt solution is 0.4-0.6:1.

[0032] In some preferred embodiments, the slurry is collected by real-time monitoring of the particle size of the material at the outlet, and collection begins when the D50 of the material is ≤0.5μm.

[0033] In some preferred embodiments, the post-processing includes demagnetization, washing, and drying; The washing process reduces the concentration of impurity ions to below 20 ppm.

[0034] Furthermore, the volume of the bottom water is the same as the volume of the microchannel reactor, and the volume of the bottom water is 1.0-2.0L.

[0035] The present invention will be further described in detail below through specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments used that do not specify the manufacturer are all conventional products that can be obtained commercially.

[0036] Example 1 A method for preparing cobalt hydroxyoxide includes the following steps: S1. Dissolve cobalt chloride hexahydrate in water to prepare a cobalt solution with a cobalt concentration of 130 g / L. Then add hydrogen peroxide to the cobalt solution at a concentration of 7 kg / Mt to obtain a mixed solution. Dissolve sodium hydroxide in water to obtain a liquid alkali with a mass concentration of 32%.

[0037] S2. Fill a 1.5L microchannel reactor with water and liquid alkali as bottom water. The pH of the bottom water is 13.0. Start stirring at 400 rpm. Then, simultaneously introduce the mixed solution, liquid alkali and air into the microchannel reactor at flow rates of 10 g / min, 5 g / min and 1.5 kg / h, respectively. The precipitation reaction is carried out, and the particle size of the material at the outlet is monitored in real time. When the particle size stabilizes at D50≤0.5μm, collection begins.

[0038] S3. The collected slurry is demagnetized through circulation until it meets the requirements. Then it is washed until the chloride ion concentration in the washing liquid is less than 20 ppm. Finally, it is transferred to a vacuum oven for drying to obtain cobalt hydroxyl oxide with a water content of less than 0.5%.

[0039] Example 2 A method for preparing cobalt hydroxyoxide includes the following steps: S1. Dissolve cobalt chloride hexahydrate in water to prepare a cobalt solution with a cobalt concentration of 130 g / L. Then add hydrogen peroxide to the cobalt solution at a concentration of 7 kg / Mt to obtain a mixed solution. Dissolve sodium hydroxide in water to obtain a liquid alkali with a mass concentration of 32%.

[0040] S2. Fill a 1.5L microchannel reactor with water and liquid alkali as bottom water. The pH of the bottom water is 13.0. Start stirring at 400 rpm. Then, simultaneously introduce the mixed solution, liquid alkali and air into the microchannel reactor at flow rates of 10 g / min, 5 g / min and 2.0 kg / h, respectively. Perform a precipitation reaction and monitor the particle size of the material at the outlet in real time. When the particle size stabilizes at D50≤0.5μm, start collecting.

[0041] S3. The collected slurry is demagnetized through circulation until it meets the requirements. Then it is washed until the chloride ion concentration in the washing liquid is less than 20 ppm. Finally, it is transferred to a vacuum oven for drying to obtain cobalt hydroxyl oxide with a water content of less than 0.5%.

[0042] Example 3 A method for preparing cobalt hydroxyoxide includes the following steps: S1. Dissolve cobalt chloride hexahydrate in water to prepare a cobalt solution with a cobalt concentration of 130 g / L. Then add hydrogen peroxide to the cobalt solution at a concentration of 7 kg / Mt to obtain a mixed solution. Dissolve sodium hydroxide in water to obtain a liquid alkali with a mass concentration of 32%.

[0043] S2. Fill a 1.5L microchannel reactor with water and liquid alkali as bottom water. The pH of the bottom water is 13.0. Start stirring at 400 rpm. Then, simultaneously introduce the mixed solution, liquid alkali and air into the microchannel reactor at flow rates of 10 g / min, 5 g / min and 2.5 kg / h, respectively. Perform a precipitation reaction and monitor the particle size of the material at the outlet in real time. When the particle size stabilizes at D50≤0.5μm, start collecting.

[0044] S3. The collected slurry is demagnetized through circulation until it meets the requirements. Then it is washed until the chloride ion concentration in the washing liquid is less than 20 ppm. Finally, it is transferred to a vacuum oven for drying to obtain cobalt hydroxyl oxide with a water content of less than 0.5%.

[0045] Example 4 A method for preparing cobalt hydroxyoxide includes the following steps: S1. Dissolve cobalt chloride hexahydrate in water to prepare a cobalt solution with a cobalt concentration of 130 g / L. Then add hydrogen peroxide to the cobalt solution at a concentration of 7 kg / Mt to obtain a mixed solution. Dissolve sodium hydroxide in water to obtain a liquid alkali with a mass concentration of 32%.

[0046] S2. Fill a 1.5L microchannel reactor with water and liquid alkali as bottom water. The pH of the bottom water is 13.0. Start stirring at 400 rpm. Then, simultaneously introduce the mixed solution, liquid alkali and air into the microchannel reactor at flow rates of 10 g / min, 5 g / min and 3.0 kg / h, respectively. The precipitation reaction is carried out, and the particle size of the material at the outlet is monitored in real time. When the particle size stabilizes at D50≤0.5μm, collection begins.

[0047] S3. The collected slurry is demagnetized through circulation until it meets the requirements. Then it is washed until the chloride ion concentration in the washing liquid is less than 20 ppm. Finally, it is transferred to a vacuum oven for drying to obtain cobalt hydroxyl oxide with a water content of less than 0.5%.

[0048] Comparative Example 1 A method for preparing cobalt hydroxyoxide includes the following steps: S1. Dissolve cobalt chloride hexahydrate in water to prepare a cobalt solution with a cobalt concentration of 130 g / L. Then add hydrogen peroxide to the cobalt solution at a concentration of 7 kg / Mt to obtain a mixed solution. Dissolve sodium hydroxide in water to obtain a liquid alkali with a mass concentration of 32%.

[0049] S2. Fill a 1.5L microchannel reactor with water and liquid alkali as bottom water. The pH of the bottom water is 13.0. Start stirring at 400 rpm. Then, simultaneously introduce the mixed solution, liquid alkali and air into the microchannel reactor at flow rates of 10 g / min, 5 g / min and 1.0 kg / h, respectively. Perform a precipitation reaction and monitor the particle size of the material at the outlet in real time. When the particle size stabilizes at D50≤0.5μm, start collecting.

[0050] S3. The collected slurry is demagnetized through circulation until it meets the requirements. Then it is washed until the chloride ion concentration in the washing liquid is less than 20 ppm. Finally, it is transferred to a vacuum oven for drying to obtain cobalt hydroxyl oxide with a water content of less than 0.5%.

[0051] Comparative Example 2 The difference from the example is that the pH of the bottom water in step S2 is 10.5.

[0052] Comparative Example 3 The difference from Example 1 is that no air is introduced during the reaction in the channel reactor.

[0053] Since the amount of hydrogen peroxide added to the mixed solution is 7 kg / Mt, meaning there is only 7 kg of hydrogen peroxide in one ton of mixed solution, it is insufficient to effectively oxidize divalent cobalt to trivalent cobalt. The product prepared in Comparative Example 2 is mainly cobalt hydrate, and cobalt hydroxyl oxide cannot be obtained.

[0054] Test case The microstructure of cobalt hydroxyl oxide prepared in Examples 1-3 and Comparative Examples 1-2 was observed using scanning electron microscopy. It should be noted that due to aggregation, the specific size is difficult to discern in the SEM images; the observed structures are all composed of aggregated nanoparticles. In particle size analysis of the cobalt hydroxyl oxide materials in Examples 1-3 and Comparative Examples 1-2, the particle size was 0.4-0.5 μm.

[0055] from Figures 1-4 , Figures 5-8 , Figures 9-12 , Figures 13-16 As can be seen, Comparative Example 1 and Example 1 with lower airflow rates exhibit obvious sheet-like structures, with the particles in Comparative Example 1 appearing as larger lumps, while Example 1 shows an overall mass of small particle agglomerates. In contrast, Examples 2 and 3 with higher airflow rates show almost no sheet-like structures, both exhibiting relatively uniform particle shapes, with Example 3 showing smaller particle sizes than Example 2. These results also demonstrate that controlling the airflow rate can produce cobalt hydroxyl oxide with varying morphologies and sizes. Figure 17As can be seen, cobalt oxide obtained from lower pH bottom water transforms from a blocky structure into a flower-like structure of tiny flakes. In downstream lithium-ion battery materials, the flake structure performs worse than the particulate agglomeration structure in forming electrode materials. These results also demonstrate that only by optimizing the air inflow rate and strictly controlling the pH of the bottom water can high-performance precursor materials be obtained.

[0056] In summary, this invention uses a microchannel reactor to prepare cobalt hydroxyl oxide, achieving millisecond-level mixing and second-level residence time control, avoiding local overheating and by-product generation; it adopts a continuous flow mode, with no scale-up effect, and can achieve industrial production through "quantity scaling up"; it has a small liquid holdup, high intrinsic safety, flexible operation, and can be modularly scaled up in parallel.

[0057] This invention optimizes the composition of the reaction system and, by controlling the air flow rate, prepares cobalt hydroxyl oxides with different morphologies and sizes, which can be adapted to different downstream application requirements.

[0058] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing cobalt hydroxyoxide, characterized in that, include, A divalent cobalt solution and liquid alkali are passed into a microchannel reactor containing bottom water to carry out a precipitation reaction. Collect the slurry and perform post-processing to obtain cobalt hydroxyoxide; The divalent cobalt solution also contains an oxidant, the pH of the bottom water is 12.0-14.0, and air is continuously introduced into the microchannel reactor at a flow rate of 1.5-3.0 kg / h during the precipitation reaction.

2. The method for preparing cobalt hydroxyoxide according to claim 1, characterized in that, The concentration of cobalt in the divalent cobalt solution is 120-140 g / L, and the concentration of the oxidant is 6-8 kg / Mt.

3. The method for preparing cobalt hydroxyoxide according to claim 1, characterized in that, The mass concentration of the liquid alkali is 30%-40%.

4. The method for preparing cobalt hydroxyoxide according to claim 1, characterized in that, The flow rate of the divalent cobalt solution is 5.0-20.0 g / min.

5. The method for preparing cobalt hydroxyoxide according to claim 4, characterized in that, The flow rate ratio of the liquid alkali to the divalent cobalt solution is 0.4-0.6:

1.

6. The method for preparing cobalt hydroxyoxide according to claim 1, characterized in that, The slurry is collected by real-time monitoring of the particle size at the discharge port. Collection begins when the D50 of the material is ≤0.5μm.

7. The method for preparing cobalt hydroxyoxide according to claim 1, characterized in that, The post-processing includes demagnetization, washing, and drying; The washing process reduces the concentration of impurity ions to below 20 ppm.

8. The method for preparing cobalt hydroxyoxide according to any one of claims 1-7, characterized in that, The volume of the bottom water is the same as the volume of the microchannel reactor, and the volume of the bottom water is 1.0-2.0L.

9. A cobalt hydroxyl oxide, characterized in that, It is obtained by the preparation method according to any one of claims 1-8.

10. The application of cobalt hydroxyoxide as described in claim 9 in lithium batteries, catalysts, and functional fillers.

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