A method for rapidly and efficiently preparing aluminum-magnesium uniformly doped cobalt oxyhydroxide

Abstract

The application provides a method for rapidly and efficiently preparing aluminum-magnesium uniformly doped hydroxyl cobalt oxide, which comprises the following steps: adding an aluminum salt and a magnesium salt into a cobalt ion-containing aqueous solution to obtain a first mixed solution; slowly adding hydrogen peroxide into the first mixed solution under rapid stirring to obtain a second mixed solution; adding the second mixed solution and a sodium hydroxide solution into a reaction container in a certain proportion under stirring, and obtaining a product containing a precipitate by controlling feeding time, reaction temperature and reaction time; and finally, obtaining a target product through solid-liquid separation, washing and drying. The aluminum-magnesium uniformly doped hydroxyl cobalt oxide prepared by the method has the advantages of small particle size, high specific surface area, uniform doping and controllable doping amount, etc.; the preparation process is simple and rapid, and the aluminum-magnesium elements can be uniformly doped under the conditions of rapidness and low energy consumption, and the phenomenon of element aggregation is avoided, so that the method has certain popularization and application prospects.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of cobalt material preparation, and particularly relates to a method for rapidly and efficiently preparing aluminum-magnesium uniformly doped hydroxyl cobalt oxide. BACKGROUND

[0002] Under the background of continuous updating and iteration of 3C products and rapid development of high-end intelligent devices, the demand for battery thinning and high-capacity is increasing. In view of this trend, the research field faces double challenges: one is to improve the compaction density of the material, and the other is to significantly improve the gram specific capacity of lithium cobalt oxide. In this process, the doping of different elements plays a key role in optimizing the structure of lithium cobalt oxide.

[0003] The doping of Al element has attracted widespread attention due to its unique advantages: first, Al 3+ has similar ionic radius and same valence as Co 3+ ; second, Al element has a single valence, which is conducive to stabilizing the material structure; third, it can improve the charging voltage of the positive electrode material and enhance the thermal stability of the material; finally, the bond energy of Al-O bond is higher than that of C-O bond, and currently aluminum-doped cobalt oxide occupies a dominant position in the market. Therefore, the present application aims to further improve the performance of lithium cobalt oxide by optimizing the doping elements.

[0004] Doping of divalent Mg element in lithium cobalt oxide can effectively improve the electrical conductivity of the material while maintaining the crystal structure, and maintain the stability of the single-phase structure during the charging and discharging cycle. When Mg element occupies Co site, it can significantly improve the voltage performance and cycle stability of the material.

[0005] The patent document with publication number CN118270854A discloses a nano-doped hydroxyl cobalt oxide and its preparation method and application. The patent prepares nano-doped hydroxyl cobalt oxide by liquid phase synthesis method, which includes first preparing a mixed solution of cobalt salt, doped aluminum salt and hydrogen peroxide, then preparing a bottom solution containing sodium hydroxide and ammonia, mixing the two solutions, and co-precipitating the doped hydroxyl cobalt oxide in the solution system. The patent lists several embodiments by changing the feeding sequence, and the BET of the synthesized hydroxyl cobalt oxide is 30-120 m 2 / g. However, the patent has the following problems: (1) only aluminum element is doped, which cannot guarantee the electrical conductivity and cycle stability of the material; (2) many process nodes need to be controlled during synthesis; (3) using ammonia as a complexing agent increases the difficulty of wastewater treatment; (4) the synthesis requires 4h, which increases the cost.

[0006] Therefore, it is a technical problem to be solved to provide a method for rapidly and efficiently preparing aluminum-magnesium uniformly doped hydroxyl cobalt oxide. SUMMARY

[0007] One of the purposes of the present application is to provide a method for quickly and efficiently preparing aluminum and magnesium uniformly doped hydroxyl cobalt oxide.

[0008] The second purpose of the present application is to provide aluminum and magnesium uniformly doped hydroxyl cobalt oxide.

[0009] The technical solution adopted by one of the purposes of the present application is to provide a method for quickly and efficiently preparing aluminum and magnesium uniformly doped hydroxyl cobalt oxide, comprising the following steps:

[0010] S1, aluminum salt and magnesium salt are added to an aqueous solution with a cobalt aluminum magnesium metal element mass ratio of 1000:(6-14):(2-5) and a cobalt ion concentration of 130-140 g / L to obtain a first mixed solution;

[0011] S2, under the condition of stirring speed of 1200-1400 r / min, 0.2%-0.6% volume percentage of hydrogen peroxide is slowly added to the first mixed solution to obtain a second mixed solution;

[0012] S3, under the condition of stirring speed of 500-700 r / min, the second mixed solution and sodium hydroxide solution are simultaneously injected into a reaction container containing bottom water according to the volume ratio of 1:(4-6), the feeding time is controlled to be 3-10 min, and the reaction is carried out under the condition of continuing stirring at a temperature of 20-40℃ for 5-20 min to obtain a product;

[0013] S4, the product is subjected to solid-liquid separation, washing and drying to obtain aluminum and magnesium uniformly doped hydroxyl cobalt oxide.

[0014] The general idea of the present application is as follows: in order to quickly and efficiently realize the preparation of aluminum and magnesium uniformly doped hydroxyl cobalt oxide, the present application improves the conventional preparation method, mainly controls the oxidation degree by controlling the proportion and method of hydrogen peroxide addition, and accelerates the reaction time by controlling the feeding method, feeding speed and stirring speed.

[0015] In the preparation method provided by the present application, first, during the preparation of cobalt solution, after the cobalt aluminum magnesium elements are uniformly dissolved, hydrogen peroxide is slowly added under the condition of rapid stirring. By increasing the stirring speed when hydrogen peroxide is fed, the cobalt solution is rapidly dispersed, and high stirring speed can rapidly oxidize cobalt ions, so that the cobalt ions are in a high active state. Secondly, by controlling the ratio of the first mixed solution containing cobalt to hydrogen peroxide, rapid oxidation and uniform co-precipitation are realized. Finally, in the feeding and reaction stage, the feeding method is improved, and the feeding time is shortened to 1-10 min to achieve the purpose of rapid feeding. In addition, the present application also controls the feeding time to make the feeding speed and the bottom water speed reach the optimal ratio, promote the uniform co-precipitation of raw materials, and realize uniform doping.

[0016] Further, in the present application, the dosage ratio of hydrogen peroxide to cobalt-containing solution is a key factor determining the reaction time, product particle size and morphology. The present application sets the amount of hydrogen peroxide added to be 0.2%-0.6% of the volume percentage of the first mixed solution containing cobalt. After a large amount of research and exploration, when the dosage of hydrogen peroxide is lower than this range, the divalent cobalt cannot be fully oxidized to trivalent cobalt, and at the same time the reaction time is prolonged, which cannot meet the demand of rapid preparation; while when the dosage of hydrogen peroxide is higher than this range, the particle size and morphology of the product will change, and the product particles will become solid, reducing the specific surface area, which cannot effectively meet the subsequent application requirements. Preferably, the amount of hydrogen peroxide added is 0.5%-0.6% of the volume percentage of the first mixed solution containing cobalt.

[0017] Further, in step S1, the cobalt salt used to prepare the aqueous solution of cobalt ions is selected from cobalt chloride and / or cobalt sulfate; the aluminum salt is selected from a combination of one or more of aluminum chloride hexahydrate, aluminum sulfate octadecahydrate, and aluminum nitrate; and the magnesium salt is selected from magnesium chloride hexahydrate and / or magnesium sulfate heptahydrate.

[0018] Further, in step S1, the mass ratio of cobalt, aluminum and magnesium is 1000:(6-10):(2-3).

[0019] Further, in step S2, the addition speed of hydrogen peroxide is controlled to be 40-60 mL / min.

[0020] Preferably, in step S2, as the content of magnesium in the first mixed solution increases, the rotation speed gradually increases when hydrogen peroxide is added, and the volume percentage of hydrogen peroxide added also increases. Among them, the increase in the volume percentage of hydrogen peroxide added makes it more conducive to co-precipitation with magnesium ions after cobalt is oxidized; and the external rotation speed also increases, which can promote the rapid mixing and uniformity of cobalt, aluminum and magnesium, avoiding the occurrence of element segregation.

[0021] Further, in step S2, the concentration of the hydrogen peroxide is 25wt.%-30 wt.%.

[0022] Further, in step S3, the content of the bottom water in the reaction container is 40%-50% of the volume of the reaction container.

[0023] Further, in step S3, the concentration of the sodium hydroxide solution is 0.1-0.2 mol / L.

[0024] Further, in step S3, the flow rate of the second mixed solution is 10-30 L / min.

[0025] Further, in step S3, the feeding time is 1-5 min, and the reaction time is 8-12 min.

[0026] Preferably, the feeding method used in step S3 is as follows: a pre-storage container for the reaction solution is set above the reaction vessel, and a lifting device (such as a lift pump) is used to pre-pump the second mixed solution into the pre-storage container; then, during the feeding stage, gravity is used to add the second mixed solution from the pre-storage container into the reaction vessel all at once. Compared with the traditional method of relying on a pump to introduce the reaction solution into the reaction vessel, this method significantly shortens the feeding time (feeding time is 1-3 minutes), better meeting the needs of rapid reaction and preparation.

[0027] The second objective of this invention is to provide a uniformly doped aluminum-magnesium cobalt oxyhydroxide, which is prepared by the preparation method described in one of the objectives of this invention.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] (1) The present invention provides a rapid and efficient method for preparing aluminum-magnesium uniformly doped cobalt hydroxyl oxide. The reaction is simple and rapid, and can achieve uniform doping of aluminum and magnesium elements under rapid and low energy consumption conditions, ensuring the uniform distribution of elements in the material, avoiding the occurrence of element aggregation, and ensuring the stability of the doping amount in the product.

[0030] (2) The method provided by this invention can also prepare cobalt hydroxyl oxide uniformly doped with aluminum and magnesium elements without the need to add EDTA or ammonia as a complexing agent. Compared with conventional preparation processes, the method of this invention avoids the introduction of organic matter or impurities by not adding EDTA or ammonia, thus avoiding the generation of COD in wastewater and increasing treatment costs, which is more in line with the concept of green environmental protection.

[0031] (3) The aluminum-magnesium uniformly doped cobalt hydroxyoxide prepared by the present invention has advantages such as small particle size, high specific surface area, uniform doping and controllable doping amount, and has broad prospects for promotion and application in lithium-ion battery cathode materials. Attached Figure Description

[0032] Figure 1 This is a scanning electron microscope image of uniformly doped cobalt hydroxyoxide with aluminum and magnesium obtained in Example 1 of the present invention.

[0033] Figure 2 This is a scanning electron microscope image of uniformly doped cobalt hydroxyoxide with aluminum and magnesium obtained in Example 2 of the present invention.

[0034] Figure 3 This is a scanning electron microscope image of uniformly doped cobalt hydroxyoxide with aluminum and magnesium obtained in Example 3 of the present invention.

[0035] Figure 4 This is a scanning electron microscope image of uniformly doped cobalt hydroxyoxide with aluminum and magnesium obtained in Example 4 of the present invention.

[0036] Figure 5 A scanning electron microscope image of the aluminum and magnesium uniformly doped hydroxyl cobalt oxide prepared for the embodiment 5 of the present application;

[0037] Figure 6 A scanning electron microscope image of the aluminum and magnesium uniformly doped hydroxyl cobalt oxide prepared for the embodiment 6 of the present application;

[0038] Figure 7 A scanning electron microscope image of the aluminum and magnesium uniformly doped hydroxyl cobalt oxide prepared for the embodiment 7 of the present application;

[0039] Figure 8 A scanning electron microscope image of the aluminum and magnesium uniformly doped hydroxyl cobalt oxide prepared for the embodiment 8 of the present application;

[0040] Figure 9 A scanning electron microscope image of the aluminum and magnesium uniformly doped hydroxyl cobalt oxide prepared for the embodiment 9 of the present application;

[0041] Figure 10 A scanning electron microscope image of the aluminum and magnesium uniformly doped hydroxyl cobalt oxide prepared for the embodiment 10 of the present application;

[0042] Figure 11 An element distribution test image of the aluminum and magnesium uniformly doped hydroxyl cobalt oxide prepared for the embodiment 3 of the present application. DETAILED DESCRIPTION

[0043] The technical solutions of the present application will be clearly and completely described below with embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work are within the protection scope of the present application.

[0044] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0045] The embodiment of the present application provides a method for rapidly and efficiently preparing aluminum and magnesium uniformly doped hydroxyl cobalt oxide, which comprises the following steps:

[0046] Step 1: aluminum salt and magnesium salt are added into a water solution with a cobalt ion concentration of 130-140 g / L according to the mass ratio of cobalt aluminum magnesium metal elements of 1000:(6-10):(2-3) to obtain a first mixed solution; wherein the cobalt salt is selected from cobalt chloride and / or cobalt sulfate; the aluminum salt is selected from one or more combinations of aluminum chloride hexahydrate, aluminum sulfate octadecahydrate and aluminum nitrate; the magnesium salt is selected from magnesium chloride hexahydrate and / or magnesium sulfate heptahydrate;

[0047] Step 2: slowly add hydrogen peroxide with a mass concentration of 25wt.%-30wt.% to the first mixed solution at a stirring speed of 1200-1400r / min and a volume percentage of 0.2%-0.6%, and the adding speed of hydrogen peroxide is controlled at 40-60mL / min to obtain a second mixed solution;

[0048] Step 3: inject bottom water into a reaction container, and the volume of the bottom water accounts for 40%-50% of the total volume of the reaction container; under the condition of a stirring speed of 500-700r / min, simultaneously inject the second mixed solution and a sodium hydroxide solution with a concentration of 0.1-0.2mol / L into the reaction container containing the bottom water at a volume ratio of 1:(4-6), and the feeding time is controlled at 1-10min, wherein the flow rate of the second mixed solution is 10-30L / min; continue to stir under the condition of a reaction temperature of 20-40℃ for 5-20min to obtain a product;

[0049] Step 4: perform solid-liquid separation on the product by centrifugal treatment, and then perform washing and drying to obtain aluminum-magnesium uniformly doped hydroxyl cobalt oxide.

[0050] The application will be further described in combination with specific examples, but not as a limitation of the application.

[0051] In the embodiments of the application, aluminum chloride hexahydrate is used as the aluminum salt, magnesium chloride hexahydrate is used as the magnesium salt, the mass concentration of hydrogen peroxide is 30wt.%, and the concentration of the sodium hydroxide solution is 0.1mol / L.

[0052] Example 1

[0053] The embodiment of the application provides a method for rapidly and efficiently preparing aluminum-magnesium uniformly doped hydroxyl cobalt oxide, which comprises the following steps:

[0054] Step 1: add aluminum salt and magnesium salt into an aqueous solution with a cobalt ion concentration of 130g / L according to a metal mass ratio of cobalt-aluminum-magnesium of 1000:6:2 to obtain a first mixed solution; wherein, cobalt chloride is used as the cobalt salt;

[0055] Step 2: slowly add hydrogen peroxide to the first mixed solution at a stirring speed of 1200r / min and a volume percentage of 0.5%, and the adding speed of hydrogen peroxide is controlled at 50mL / min to obtain a second mixed solution;

[0056] Step 3: A reaction liquid pre-storage container is arranged above the reaction container, and a second mixed solution and a sodium hydroxide solution required for the reaction are respectively pre-injected into the corresponding reaction liquid pre-storage container by using a lifting pump; bottom water is injected into the reaction container, and the bottom water accounts for 50% of the total volume of the reaction container; under the condition that the stirring speed is 600 r / min, the second mixed solution and the sodium hydroxide solution in the reaction liquid pre-storage container are simultaneously and once added into the reaction container containing the bottom water by using gravity, and the feeding time is controlled within 3 min. The flow rate of the second mixed solution is 20 L / min, and the product is obtained by continuing to stir under the condition that the reaction temperature is 25℃ for 10 min;

[0057] Step 4: The product is subjected to solid-liquid separation by centrifugal treatment, and then washed and dried to obtain aluminum-magnesium uniformly doped hydroxyl cobalt oxide.

[0058] Example 2

[0059] The difference between this example and Example 1 is that the metal mass ratio of cobalt-aluminum-magnesium in Step 1 is adjusted to 1000:7:2, and the rest of the conditions and operations remain unchanged, and aluminum-magnesium uniformly doped hydroxyl cobalt oxide is prepared.

[0060] Example 3

[0061] The difference between this example and Example 1 is that the metal mass ratio of cobalt-aluminum-magnesium in Step 1 is adjusted to 1000:8:2, and the rest of the conditions and operations remain unchanged, and aluminum-magnesium uniformly doped hydroxyl cobalt oxide is prepared.

[0062] Example 4

[0063] The difference between this example and Example 1 is that the metal mass ratio of cobalt-aluminum-magnesium in Step 1 is adjusted to 1000:10:2, and the rest of the conditions and operations remain unchanged, and aluminum-magnesium uniformly doped hydroxyl cobalt oxide is prepared.

[0064] Example 5

[0065] The difference between this example and Example 1 is that cobalt chloride in Step 1 is replaced by cobalt sulfate, and the rest of the conditions and operations remain unchanged, and aluminum-magnesium uniformly doped hydroxyl cobalt oxide is prepared.

[0066] Example 6

[0067] The difference between this example and Example 1 is that in Step 2, hydrogen peroxide is slowly added to the first mixed solution at a volume percentage of 0.20%, and the rest of the conditions and operations remain unchanged, and aluminum-magnesium uniformly doped hydroxyl cobalt oxide is prepared.

[0068] Example 7

[0069] The difference between the present example and Example 1 is that the flow rate of the second mixed solution and the sodium hydroxide solution in step 3 is adjusted, the feeding time is controlled to be 10 min, the reaction time is controlled to be 10 min, and the rest of the conditions and operations are unchanged, thereby obtaining aluminum-magnesium uniformly doped hydroxyl cobalt oxide.

[0070] Example 8

[0071] The difference between the present example and Example 3 is that the metal mass ratio of cobalt, aluminum and magnesium in step 1 is adjusted to be 1000:8:3, and the hydrogen peroxide is slowly added to the first mixed solution in step 2 at a stirring speed of 1250 r / min and a volume percentage of 0.52%. The rest of the conditions and operations are unchanged, thereby obtaining aluminum-magnesium uniformly doped hydroxyl cobalt oxide.

[0072] Example 9

[0073] The difference between the present example and Example 3 is that the metal mass ratio of cobalt, aluminum and magnesium in step 1 is adjusted to be 1000:8:4, and the hydrogen peroxide is slowly added to the first mixed solution in step 2 at a stirring speed of 1300 r / min and a volume percentage of 0.54%. The rest of the conditions and operations are unchanged, thereby obtaining aluminum-magnesium uniformly doped hydroxyl cobalt oxide.

[0074] Example 10

[0075] The difference between the present example and Example 3 is that the metal mass ratio of cobalt, aluminum and magnesium in step 1 is adjusted to be 1000:8:5, and the hydrogen peroxide is slowly added to the first mixed solution in step 2 at a stirring speed of 1350 r / min and a volume percentage of 0.56%. The rest of the conditions and operations are unchanged, thereby obtaining aluminum-magnesium uniformly doped hydroxyl cobalt oxide.

[0076] Performance test and characterization

[0077] The particle size and specific surface area of the aluminum-magnesium uniformly doped hydroxyl cobalt oxide prepared in Examples 1-10 of the present application are tested, and the results are shown in Table 1 below:

[0078] Table 1

[0079]

[0080] As shown in the above table, the hydroxyl cobalt oxide prepared in each example of the present application has the advantages of small particle size and high specific surface area.

[0081] Figures 1-10 The scanning electron microscope images of the aluminum-magnesium uniformly doped hydroxyl cobalt oxide prepared in Examples 1-10 of the present application are shown in Figures 1-10, respectively. Figures 1-10It can be seen that, in the present application, the product performance can be further optimized under the conditions of controlling the cobalt concentration at 130 g / L, a feeding time of 3 min, a reaction time of 10 min, a volume percentage of hydrogen peroxide added in the raw material solution of 0.5%, and a stirring speed of 600 r / min.

[0082] Further, examples 8-10 not only increase the content of magnesium element in the first mixed solution, but also simultaneously increase the stirring speed and the volume percentage of hydrogen peroxide added in the preparation process of the second mixed solution. The prepared product not only maintains the advantages of small particle size and high specific surface area, but also promotes the rapid mixing and uniformity of cobalt, aluminum and magnesium, and avoids the occurrence of element segregation.

[0083] Figure 11 The element distribution test chart of the aluminum-magnesium uniformly doped hydroxyl cobalt oxide prepared in example 3 of the present application is shown in FIG. 3. Figure 11 It can be seen that the aluminum and magnesium elements are uniformly distributed, and no segregation phenomenon occurs.

[0084] Further, the content of the doped elements in the product under different cobalt-aluminum-magnesium ratios in examples 1-4 is tested, and the results are shown in Table 2.

[0085] Table 2

[0086]

[0087] As can be seen from Table 2, the content of the doped elements in the aluminum-magnesium uniformly doped hydroxyl cobalt oxide prepared in the present application is basically consistent with the feeding amount (within ±200).

[0088] The above are only the preferred embodiments of the present application, and do not limit the implementation manners and protection scope of the present application. It should be realized by those skilled in the art that any equivalent replacement and obvious changes made according to the content of the present application should be included in the protection scope of the present application.

Claims

1. A method for rapidly and efficiently preparing aluminum and magnesium uniformly doped cobalt oxyhydroxide, characterized in that, The method does not add ammonia water or EDTA as a complexing agent, and the method comprises the following steps: S1, aluminum salt and magnesium salt are added into an aqueous solution with a cobalt ion concentration of 130-140 g / L according to the mass ratio of metal elements of cobalt-aluminum-magnesium being 1000:(6-14):(2-5), to obtain a first mixed solution; S2, under the condition that the stirring speed is 1200-1400 r / min, hydrogen peroxide is slowly added to the first mixed solution according to the volume percentage of 0.2%-0.6%, to obtain a second mixed solution; S3, under the condition that the stirring speed is 500-700 r / min, the second mixed solution and sodium hydroxide solution are simultaneously injected into a reaction container containing bottom water according to the volume ratio of 1:(4-6), the feeding time is controlled to be 1-10 min, and the reaction is carried out under the condition that the temperature is 20-40℃ and the stirring is continued for 5-20 min to obtain a product; S4, the product is subjected to solid-liquid separation, washing and drying to obtain an aluminum-magnesium uniformly doped hydroxyl cobalt oxide.

2. The method of claim 1, wherein, In step S1, the cobalt salt used for preparing the aqueous solution of cobalt ions is selected from cobalt chloride and / or cobalt sulfate; the aluminum salt is selected from one or more combinations of aluminum chloride hexahydrate, aluminum sulfate octadecahydrate and aluminum nitrate; and the magnesium salt is selected from magnesium chloride hexahydrate and / or magnesium sulfate heptahydrate.

3. The method of claim 1, wherein, In step S1, the mass ratio of metal elements of cobalt-aluminum-magnesium is 1000:(6-10):(2-3).

4. The method of claim 1, wherein, In step S2, the addition speed of hydrogen peroxide is 40-60 mL / min.

5. The method of claim 1, wherein, In step S2, the concentration of hydrogen peroxide is 25wt.%-30wt.%.

6. The method of claim 1, wherein, In step S3, the content of the bottom water in the reaction container accounts for 40%-50% of the volume of the reaction container.

7. The method of claim 1, wherein, In step S3, the concentration of the sodium hydroxide solution is 0.1-0.2 mol / L.

8. The method of claim 1, wherein, In step S3, the flow rate of the second mixed solution is 10-30 L / min.

9. The method of claim 1, wherein, In step S3, the feeding time is 1-5 min, and the reaction time is 8-12 min.

Images