A method for preparing spheroidized battery-grade manganese dioxide

Abstract

The application discloses a method for preparing spherical battery-grade Mn3O4, and the Mn3O4 is directly obtained through a one-step method. According to the growth characteristics of the Mn3O4 crystal particles, the on-line changes of the parameters of different growth stages of the Mn3O4 crystal are controlled and changed, and then the growth process of the Mn3O4 crystal is regulated, so that the particle size of the product is controlled and the shape of the product is optimized. Finally, the Mn3O4 product with uniform and controllable particle size and good morphology characteristics is obtained. In addition, according to the particle size of the target product, a corresponding scheme can be formulated to obtain the product meeting the requirements, and the fine control of the preparation process of the Mn3O4 is realized. The method has the advantages of short process, simple operation and low energy consumption.

Description

TECHNICAL FIELD

[0001] The application relates to preparation of a battery material, in particular to a method for preparing spherical battery-grade trimanganese tetraoxide, and belongs to the technical field of battery material production and preparation. BACKGROUND

[0002] In recent years, with the development of green industries such as new energy vehicles, lithium manganate (LiMn2O4) as a positive electrode material of power lithium ion batteries has been paid more and more attention due to the advantages of low price, good safety performance, no pollution to the environment and the like. At present, lithium manganate is mainly produced by taking electrolytic manganese dioxide as a manganese source, sintering with lithium carbonate and corresponding additives in a solid phase, and the prepared lithium manganate material has problems such as low specific capacity, poor cycle performance and poor high-temperature performance due to the defects of electrolytic manganese dioxide such as poor particle morphology. Mn3O4 and LiMn2O4 have the same spinel structure, and when LiMn2O4 is prepared from Mn3O4, no severe structural change occurs, the material structure is more stable, the prepared LiMn2O4 has more excellent electrochemical performance, and the specific capacity, high-temperature performance and cycle performance are obviously improved. Therefore, it is the current development trend to replace electrolytic manganese dioxide with Mn3O4 to produce LiMn2O4.

[0003] The preparation methods of Mn3O4 mainly include calcination, reduction, oxidation, manganese salt method and the like, and at present, the metal manganese powder suspension oxidation method is mostly used. The method is relatively mature, but the production cost is high, the purity is low, and the particle size is uneven. In recent years, the manganese salt method has been widely concerned due to the advantages of low raw material cost, and the preparation of Mn3O4 by the manganese salt method is usually divided into two steps. In the first step, an alkaline precipitating agent is added to a manganese salt to obtain Mn(OH)2 precipitate. After Mn(OH)2 is filtered and washed, Mn3O4 particles are prepared after slurry oxidation. The two-step oxidation method needs to use inert gas for protection in the whole preparation process of Mn(OH)2, and the process flow is relatively complex, and the product morphology and particle size are also difficult to control. Since the particle size, morphology and impurity content of the manganese source directly affect the electrical performance of lithium manganate material, it is of great significance to develop a short process, simple operation and particle size controllable battery-grade trimanganese tetraoxide preparation method in view of various deficiencies of the prior art. SUMMARY

[0004] In view of the problem in the prior art that the product morphology and particle size are difficult to control in the preparation of Mn3O4 by the existing manganese salt method, thereby affecting the electrical performance of the electrode material, the application provides a method for preparing spherical battery-grade Mn3O4, which directly obtains Mn3O4 by one-step method, and according to the growth characteristics of the Mn3O4 crystal particles, the online change of the parameters of different growth stages of the Mn3O4 crystal is controlled and changed, and then the growth process of the Mn3O4 crystal is regulated, so as to control the particle size of the product and optimize the shape, and finally the Mn3O4 product with uniform and controllable particle size and good morphology characteristics is obtained.

[0005] To achieve the above technical purposes, the technical solutions adopted by the application are as follows:

[0006] A method for preparing spherical battery-grade Mn3O4, which comprises the following steps:

[0007] 1) A first judgment model of the flow rate of the ammonia solution to be added at one time is established according to the target particle size of the product, the concentration of the manganese salt solution, the predetermined flow rate of the manganese salt solution to be added per unit time and the concentration of the ammonia solution, and the flow rate of the ammonia solution to be added at one time per unit time in the first stirring reaction is obtained according to the first judgment model. Deionized water is added to a reaction container and heated as a reaction bottom liquid, then the manganese salt solution is added to the reaction container under the condition of the participation of an oxidizing agent, and the ammonia solution is synchronously added according to the obtained flow rate of the ammonia solution to be added at one time to carry out the first stirring reaction.

[0008] 2) A calculation model and a second judgment model of the flow rate of the ammonia solution to be added at two times are established according to the target particle size of the product, the concentration of the manganese salt solution, the predetermined flow rate of the manganese salt solution to be added per unit time, the concentration of the ammonia solution, the flow rate of the ammonia solution to be added at one time, the stirring rate of the first stirring reaction and the predetermined stirring rate of the second stirring reaction, and the flow rate of the ammonia solution to be added at two times per unit time in the second stirring reaction is obtained according to the calculation model and the second judgment model. After the first stirring reaction is completed, the real-time flow rate of the ammonia solution is adjusted at the obtained flow rate of the ammonia solution to be added at two times, and then the second stirring reaction is carried out.

[0009] 3) After the second stirring reaction is completed, the stirring rate is reduced and the addition of the manganese salt solution and the ammonia solution is stopped until the reaction is completed. The solid product after the reaction is separated, and the battery-grade Mn3O4 product is obtained after the solid product is sequentially subjected to washing and drying treatment.

[0010] Preferably, in step 1), the first judgment model is:

[0011] a) when D < 10 μm, 0.2 ≤ (V2·C2) / (V1·C1) ≤ 0.8 per unit time.

[0012] b) when 10 μm≤D≤25 μm, 2.0≤(V2·C2) / (V1·C1)≤3.2 per unit time.

[0013] wherein D is the D50 of the target product, μm. C1 is the concentration of the manganese salt solution, mol / L. C2 is the concentration of the ammonia solution, mol / L. V1 is the predetermined flow rate of the manganese salt solution, L / h. V2 is the primary intended flow rate of the ammonia solution, L / h.

[0014] As preferred, in step 2), the calculation model is:

[0015] D = [1453C2V2(8846+r2)+48038C2V x (8102+r1)] / [(8102+r1)(8846+r2)C1V1]-0.305 (1)

[0016] D1=kD (2)

[0017] In formula (1), D is the D50 of the target product, μm. C1 is the concentration of the manganese salt solution, mol / L. C2 is the concentration of the ammonia solution, mol / L. V1 is the predetermined flow rate of the manganese salt solution, L / h. V2 is the primary intended flow rate of the ammonia solution, L / h. V x is the secondary intended flow rate of the ammonia solution, L / h. r1 is the stirring rate during the primary stirring reaction, r / min. r2 is the stirring rate during the secondary stirring reaction, r / min. In formula (2), D1 is the actual measured value of the product D50, μm. k is the error coefficient, and has a value of 0.95-1.05. The reliability of the above formula can be judged according to the value of k.

[0018] As preferred, the secondary judgment model is:

[0019] c) when D≤5 μm, 0.4≤(V x ·C2) / (V1·C1)≤1.0 per unit time.

[0020] d) when 5 μm<D≤10 μm, 1.2≤(V x ·C2) / (V1·C1)≤2.0 per unit time.

[0021] e) when 10 μm<D≤25 μm, 2.5≤(V x ·C2) / (V1·C1)≤4.0 per unit time.

[0022] and in c), d), e): (V x ·C2) / (V1·C1)-(V2·C2) / (V1·C1)≥0.2.

[0023] As preferred, in step 1), the manganese salt solution is one or more of manganese sulfate solution, manganese chloride solution, manganese nitrate solution, manganese acetate solution, preferably manganese sulfate solution.

[0024] As preferred, in step 1), the oxidant is one or more of air, oxygen, ozone, preferably oxygen (it is to be noted that the oxygen refers to oxygen-containing gas with oxygen content higher than air, preferably oxygen-containing gas with oxygen content not less than 50%, further preferably oxygen-containing gas with oxygen content not less than 80%, such as pure oxygen).

[0025] As preferred, in step 1), the concentration of the manganese salt solution is 1-5 mol / L, preferably 1.5-4.5 mol / L, more preferably 2-4 mol / L. The predetermined flow rate of the manganese salt solution is 1-10 L / h, preferably 1.5-8 L / h, more preferably 2-6 L / h.

[0026] As preferred, in step 1), the concentration of the ammonia solution is 1-5 mol / L, preferably 1.5-4.5 mol / L, more preferably 2-4 mol / L.

[0027] As preferred, in step 1), the heating is heating the reaction bottom liquid to 45-85℃, preferably 50-80℃, more preferably 55-75℃.

[0028] As preferred, in step 1), the manganese salt solution and the ammonia solution are independently preheated before being added to the reaction vessel. Preferably, the temperature of the preheated manganese salt solution and the preheated ammonia solution are consistent with the temperature of the heated reaction bottom liquid.

[0029] As preferred, in step 1), the stirring rate during the first stirring reaction is not less than 400 r / min, preferably 600-800 r / min, more preferably 650-750 r / min. The duration of the first stirring reaction is not more than 8 h, preferably 1-6 h, more preferably 2-4 h.

[0030] As preferred, in step 2), the stirring rate during the second stirring reaction is not less than 200 r / min, preferably 400-800 r / min, more preferably 450-700 r / min. The duration of the second stirring reaction is not less than 2 h, preferably 3-24 h, more preferably 5-20 h.

[0031] It is to be noted that the increase of the stirring rate will inhibit the adhesion of solute particles and the agglomeration between fine grains, thereby inhibiting the growth of secondary particles. Therefore, generally when preparing products with larger particle size, the secondary stirring rate needs to be appropriately reduced.

[0032] Preferably, in step 3), the stirring rate after reducing the stirring rate is not higher than 500 r / min, preferably 100 to 400 r / min, and more preferably 150 to 300 r / min.

[0033] Preferably, in step 3), the washing is performed using deionized water, preferably 1 to 10 times, and more preferably 2 to 8 times.

[0034] In this invention, a one-step method is used to directly prepare manganese tetroxide products with the target particle size. First, a manganese salt solution of a certain concentration (e.g., a manganese sulfate solution with a concentration of 1-5 mol / L, generally prepared by adding deionized water to high-purity manganese sulfate monohydrate solid) and an ammonia solution of a certain concentration (e.g., an ammonia solution with a concentration of 1-5 mol / L, generally prepared by adding deionized water to concentrated ammonia) are prepared. Then, they are continuously added to a reaction vessel at a certain flow rate to carry out a preliminary reaction. An oxidant (e.g., continuously purifying pure oxygen) is added during the reaction. After the preliminary reaction is completed (e.g., after stirring for 2-5 hours), the amount of ammonia added is selectively adjusted according to the target particle size of the product, and the reaction is continued. This yields a manganese tetroxide product with the target particle size, uniform morphology, and extremely low impurity content.

[0035] In this invention, sufficient deionized water is added to the reaction vessel beforehand as a base liquid and preheated to the reaction temperature. The purpose of this is to control the reaction temperature to the set temperature. Furthermore, the manganese salt solution and ammonia solution are also preheated to the reaction temperature before the reaction to reduce the impact of large temperature differences on the reaction.

[0036] In this invention, Mn3O4 is obtained directly in one step, and the main reactions occurring during its preparation process are as follows:

[0037] 6Mn 2+ +O2+12NH3·H2O=2Mn3O4+12NH4 + +6H2O

[0038] During the reaction, Mn 2+ Mn3O4 and H are generated under the action of oxidant. + The role of ammonia in the system is mainly twofold: firstly, to neutralize the H+ generated in the solution. + To avoid a continuous decrease in the system pH, which would affect the phase composition and reaction rate of the product, and secondly, to react with Mn 2+ Coordination generates complexes, regulating the Mn system. 2+ Supersaturation. This method is a one-step process, where Mn is controlled by appropriate reaction conditions. 2+The method is short in process flow, simple in operation, and the obtained product has controllable particle size, uniform and good morphology characteristics, and extremely low impurity content.

[0039] In the application, the growth process of Mn3O4 crystals in the reaction solution mainly experiences the following processes. Firstly, the monomer concentration gradually increases to saturation in the system. When the monomer concentration exceeds a certain limit, a large number of nucleation begins, which is the nucleation stage. Then, the monomer concentration sharply decreases, and the nucleation reaction ends. After nucleation, the nanoparticles continue to grow through the diffusion between monomer molecules until the complete crystal structure is formed. Because the different growth stages of the crystals have different characteristics, the experimental parameters have different effects on the growth in the process, so the nucleation and growth process of the crystals is finely designed, and the particle size and shape of the product are controlled by fine control of the process parameters. That is, the growth of Mn3O4 is divided into multiple stages, and the target particle size of Mn3O4 product is obtained by fine control of the temperature, stirring speed and liquid feeding rate of each stage, and the shape is optimized.

[0040] In the application, under the given working conditions, the product particle size is controlled by controlling the flow rate of ammonia water and other parameters in different stages of the reaction, and the required product can be obtained according to the particle size of the target product, so as to realize the fine control of the preparation process of Mn3O4. The main process is as follows: D is the D50 of the target product, μm. C1 is the concentration of the manganese salt solution, mol / L. C2 is the concentration of the ammonia water solution, mol / L. V1 is the initial feeding rate of the manganese salt solution, L / h. V2 is the initial feeding rate of the ammonia water solution, L / h. r1 is the stirring speed at the initial reaction, r / min. r2 is the stirring speed after adjusting the feeding rate of the ammonia water solution, r / min. Then the feeding rate V x (mol / L) should satisfy the following formula:

[0041] D=[1453C2V2(8846+r2)+48038C2V x (8102+r1)] / [(8102+r1)(8846+r2)C1V1]-0.305(1)

[0042] Further, to realize fine control of the product particle size, the molar ratio of the amount of ammonia water to the amount of manganese salt per unit time at the initial reaction (i.e. the first stage of reaction) is set as m1. The molar ratio of the amount of ammonia water to the amount of manganese salt per unit time after adjusting the amount of ammonia water (i.e. the second stage of reaction) is set as m2. Then,

[0043] a) when D < 10 μm, 0.2 ≤ (V2·C2) / (V1·C1) ≤ 0.8 per unit time.

[0044] b) when 10 μm ≤ D ≤ 25 μm, 2.0 ≤ (V2·C2) / (V1·C1) ≤ 3.2 per unit time.

[0045] c) when D ≤ 5 μm, 0.4 ≤ (V x ·C2) / (V1·C1) ≤ 1.0 per unit time.

[0046] d) when 5 μm < D ≤ 10 μm, 1.2 ≤ (V x ·C2) / (V1·C1) ≤ 2.0 per unit time.

[0047] e) when 10 μm < D ≤ 25 μm, 2.5 ≤ (V x ·C2) / (V1·C1) ≤ 4.0 per unit time.

[0048] and in c), d), e): (V x ·C2) / (V1·C1) - (V2·C2) / (V1·C1) ≥ 0.2.

[0049] That is, the present application, by the above process, uses a one-step method to directly prepare the Mn304 product, and the actual particle size of the Mn304 product is highly matched with the target particle size D, and the product morphology is basically spherical or spherical-like.

[0050] Compared with the prior art, the present application has the following beneficial technical effects:

[0051] 1: According to the growth characteristics of the Mn304 crystal particles, the present application precisely controls the process parameters in different growth stages of the Mn304 particles, and then controls the growth process of the Mn304 crystal, so as to precisely control the particle size of the product and optimize the shape of the target. In addition, the present application can also formulate a corresponding scheme according to the particle size of the target product to obtain a product meeting the requirements, and realize fine control of the preparation process of the Mn304.

[0052] 2: The present application uses a one-step method to directly prepare the battery-grade Mn304 product, which has the advantages of short process, simple operation, and low energy consumption. BRIEF DESCRIPTION OF DRAWINGS

[0053] Figure 1 SEM image of the product obtained in Example 3 at × 2000.

[0054] Figure 2 SEM image of the product obtained in Example 3 at × 8000.

[0055] Figure 3SEM image of the product obtained in Example 3 at × 15000.

[0056] Figure 4 XRD image of the product obtained in Example 3. DETAILED DESCRIPTION

[0057] The technical solutions of the present application are illustrated below, and the scope of protection requested by the present application includes but is not limited to the following examples.

[0058] Example 1

[0059] Preparation of trimanganese tetraoxide with D50 of 4.0 μm:

[0060] Manganese sulfate monohydrate was weighed and an appropriate amount of deionized water was added to prepare a manganese sulfate solution with a concentration of 1.2 mol / L. Concentrated ammonia water was measured and an appropriate amount of deionized water was added to prepare an ammonia water solution with a concentration of 1.2 mol / L.

[0061] 5 L of deionized water was added to the reaction kettle and heated to 60°C, then the manganese sulfate solution was added to the reaction kettle at a flow rate of 1.0 L / h and the ammonia water solution was added to the reaction kettle at a flow rate of 0.4 L / h, while the stirring device of the reaction kettle was turned on (the stirring rate was set to 800 r / min) and a sufficient amount of pure oxygen was introduced into the reaction kettle to carry out the preliminary reaction, and the reaction time was 3 h.

[0062] After the preliminary reaction was completed, the flow rate of the ammonia water solution to be adjusted was calculated according to the aforementioned parameters and formula (1), wherein the stirring rate of the secondary reaction was 800 r / min, so the flow rate of the adjusted ammonia water should be 0.85 L / h, and after adjusting the flow rate and stirring rate of the ammonia water, the secondary reaction was carried out for 11 h; after the secondary reaction was completed, the addition of the manganese sulfate solution and the ammonia water solution was stopped, the stirring rate was reduced to 200 r / min, and the aging reaction was carried out for 1 h, then the reaction slurry was filtered, the solid product was washed with deionized water for 3 times, and then dried to obtain the trimanganese tetraoxide product.

[0063] Example 2

[0064] Preparation of trimanganese tetraoxide with D50 of 8.0 μm:

[0065] Manganese sulfate monohydrate was weighed and an appropriate amount of deionized water was added to prepare a manganese sulfate solution with a concentration of 1.2 mol / L. Concentrated ammonia water was measured and an appropriate amount of deionized water was added to prepare an ammonia water solution with a concentration of 2.0 mol / L.

[0066] Into a reaction kettle, 6 L of deionized water was added and heated to 70°C, then a manganese sulfate solution was added to the reaction kettle at a flow rate of 2.5 L / h and an ammonia water solution was added to the reaction kettle at a flow rate of 1.0 L / h, while the stirring device of the reaction kettle was turned on (the stirring rate was set to 700 r / min) and a sufficient amount of pure oxygen was introduced into the reaction kettle to carry out the preliminary reaction, and the reaction time was 3 h.

[0067] After the preliminary reaction was completed, the flow rate of the ammonia water solution to be adjusted was calculated according to the aforementioned parameters and formula (1), wherein the stirring rate of the secondary reaction was 600 r / min, so the flow rate of the ammonia water after adjustment should be 2.42 L / h, and after adjusting the flow rate and stirring rate of the ammonia water, the secondary reaction was carried out for 10 h; after the secondary reaction was completed, the addition of the manganese sulfate solution and the ammonia water solution was stopped, the stirring rate was reduced to 150 r / min, and the aging reaction was carried out for 1 h, after the aging was completed, the reaction slurry was filtered, the solid product was washed with deionized water for 3 times, and then dried to obtain the manganese sesquioxide product.

[0068] Example 3

[0069] Preparation of manganese sesquioxide with a D50 of 14.0 μm:

[0070] The manganese sulfate monohydrate was weighed and an appropriate amount of deionized water was added to prepare a manganese sulfate solution with a concentration of 1.5 mol / L; the concentrated ammonia water was measured and an appropriate amount of deionized water was added to prepare an ammonia water solution with a concentration of 3.0 mol / L.

[0071] Into a reaction kettle, 7 L of deionized water was added and heated to 80°C, then a manganese sulfate solution was added to the reaction kettle at a flow rate of 1.8 L / h and an ammonia water solution was added to the reaction kettle at a flow rate of 2.2 L / h, while the stirring device of the reaction kettle was turned on (the stirring rate was set to 600 r / min) and a sufficient amount of pure oxygen was introduced into the reaction kettle to carry out the preliminary reaction, and the reaction time was 4 h.

[0072] After the preliminary reaction was completed, the flow rate of the ammonia water solution to be adjusted was calculated according to the aforementioned parameters and formula (1), wherein the stirring rate of the secondary reaction was 500 r / min, so the flow rate of the ammonia water after adjustment should be 2.44 L / h, and after adjusting the flow rate and stirring rate of the ammonia water, the secondary reaction was carried out for 10 h; after the secondary reaction was completed, the addition of the manganese sulfate solution and the ammonia water solution was stopped, the stirring rate was reduced to 100 r / min, and the aging reaction was carried out for 1 h, after the aging was completed, the reaction slurry was filtered, the solid product was washed with deionized water for 3 times, and then dried to obtain the manganese sesquioxide product.

[0073] Example 4

[0074] Preparation of manganese sesquioxide with a D50 of 18.0 μm:

[0075] Manganese sulfate monohydrate was weighed and an appropriate amount of deionized water was added to prepare a manganese sulfate solution with a concentration of 2.0 mol / L; concentrated ammonia water was measured and an appropriate amount of deionized water was added to prepare an ammonia water solution with a concentration of 4.0 mol / L.

[0076] 8 L of deionized water was added to the reaction kettle and heated to 75°C, then the manganese sulfate solution was added to the reaction kettle at a flow rate of 2.0 L / h and the ammonia water solution was added to the reaction kettle at a flow rate of 2.8 L / h, while the stirring device of the reaction kettle was turned on (the stirring rate was set to 600 r / min) and sufficient pure oxygen was introduced into the reaction kettle to carry out the preliminary reaction, and the reaction time was 4 h.

[0077] After the preliminary reaction was completed, the flow rate of the ammonia water solution to be adjusted was calculated according to the above parameters and formula (1), wherein the stirring rate of the secondary reaction was 400 r / min, so the adjusted flow rate of the ammonia water should be 3.44 L / h, and after adjusting the flow rate and stirring rate of the ammonia water, the secondary reaction was carried out for 10 h; after the secondary reaction was completed, the addition of the manganese sulfate solution and the ammonia water solution was stopped, the stirring rate was reduced to 100 r / min, and the aging reaction was carried out for 1 h, then the reaction slurry was filtered, the solid product was washed with deionized water for 3 times, and then dried to obtain the manganese tetroxide product.

[0078] Example 5

[0079] Preparation of manganese tetroxide with a D50 of 8.0 μm:

[0080] Manganese sulfate monohydrate was weighed and an appropriate amount of deionized water was added to prepare a manganese sulfate solution with a concentration of 1.4 mol / L; concentrated ammonia water was measured and an appropriate amount of deionized water was added to prepare an ammonia water solution with a concentration of 2.1 mol / L.

[0081] 6 L of deionized water was added to the reaction kettle and heated to 65°C, then the manganese sulfate solution was added to the reaction kettle at a flow rate of 2.2 L / h and the ammonia water solution was added to the reaction kettle at a flow rate of 0.9 L / h, while the stirring device of the reaction kettle was turned on (the stirring rate was set to 700 r / min) and sufficient pure oxygen was introduced into the reaction kettle to carry out the preliminary reaction, and the reaction time was 3.5 h.

[0082] After the preliminary reaction was completed, the flow rate of the ammonia water solution to be adjusted was calculated according to the above parameters and formula (1), wherein the stirring rate of the secondary reaction was 600 r / min, so the adjusted flow rate of the ammonia water should be 2.37 L / h, and after adjusting the flow rate and stirring rate of the ammonia water, the secondary reaction was carried out for 11 h; after the secondary reaction was completed, the addition of the manganese sulfate solution and the ammonia water solution was stopped, the stirring rate was reduced to 100 r / min, and the aging reaction was carried out for 1 h, then the reaction slurry was filtered, the solid product was washed with deionized water for 3 times, and then dried to obtain the manganese tetroxide product.

[0083] Example 6

[0084] Preparation of trimanganese tetraoxide with D50 of 8.0 μm:

[0085] Manganese sulfate monohydrate was weighed and an appropriate amount of deionized water was added to prepare a manganese sulfate solution with a concentration of 1.4 mol / L. Concentrated ammonia water was measured and an appropriate amount of deionized water was added to prepare an ammonia water solution with a concentration of 2.1 mol / L.

[0086] 6 L of deionized water was added to the reaction kettle and heated to 65°C, then the manganese sulfate solution was added at a flow rate of 2.2 L / h and the ammonia water solution was added at a flow rate of 0.2 L / h, while the stirring device of the reaction kettle was started (the stirring rate was set to 700 r / min) and sufficient pure oxygen was introduced into the reaction kettle to carry out the preliminary reaction, and the reaction time was 3.5 h.

[0087] After the preliminary reaction was completed, the stirring rate of the secondary reaction was adjusted to 600 r / min, the flow rate of the ammonia water was adjusted to 2.37 L / h, and the secondary reaction time was 11 h; after the secondary reaction was completed, the addition of the manganese sulfate solution and the ammonia water solution was stopped, the stirring rate was reduced to 100 r / min, and the aging reaction was carried out for 1 h, then the reaction slurry was filtered, the solid product was washed with deionized water for 3 times, and then dried to obtain the trimanganese tetraoxide product.

[0088] Example 7

[0089] Preparation of trimanganese tetraoxide with D50 of 8.0 μm:

[0090] Manganese sulfate monohydrate was weighed and an appropriate amount of deionized water was added to prepare a manganese sulfate solution with a concentration of 1.4 mol / L. Concentrated ammonia water was measured and an appropriate amount of deionized water was added to prepare an ammonia water solution with a concentration of 2.1 mol / L.

[0091] 6 L of deionized water was added to the reaction kettle and heated to 65°C, then the manganese sulfate solution was added at a flow rate of 2.2 L / h and the ammonia water solution was added at a flow rate of 1.32 L / h, while the stirring device of the reaction kettle was started (the stirring rate was set to 700 r / min) and sufficient pure oxygen was introduced into the reaction kettle to carry out the preliminary reaction, and the reaction time was 3.5 h.

[0092] After the preliminary reaction was completed, the stirring rate of the secondary reaction was adjusted to 600 r / min, the flow rate of the ammonia water was adjusted to 2.37 L / h, and the secondary reaction time was 11 h; after the secondary reaction was completed, the addition of the manganese sulfate solution and the ammonia water solution was stopped, the stirring rate was reduced to 100 r / min, and the aging reaction was carried out for 1 h, then the reaction slurry was filtered, the solid product was washed with deionized water for 3 times, and then dried to obtain the trimanganese tetraoxide product.

[0093] Example 8

[0094] Preparation of trimanganese tetraoxide with D50 of 8.0 μm:

[0095] Manganese sulfate monohydrate was weighed and an appropriate amount of deionized water was added to prepare a manganese sulfate solution with a concentration of 1.4 mol / L. Concentrated ammonia water was measured and an appropriate amount of deionized water was added to prepare an ammonia water solution with a concentration of 2.1 mol / L.

[0096] 6 L of deionized water was added to the reaction kettle and heated to 65°C, then the manganese sulfate solution was added at a flow rate of 2.2 L / h and the ammonia water solution was added at a flow rate of 0.9 L / h, while the stirring device of the reaction kettle was started (the stirring rate was set to 700 r / min) and sufficient pure oxygen was introduced into the reaction kettle to carry out the preliminary reaction, and the reaction time was 3.5 h.

[0097] After the preliminary reaction was completed, the stirring rate of the secondary reaction was adjusted to 600 r / min, the flow rate of the ammonia water was adjusted to 1.46 L / h, and the secondary reaction time was 11 h; after the secondary reaction was completed, the addition of the manganese sulfate solution and the ammonia water solution was stopped, the stirring rate was reduced to 100 r / min, and the aging reaction was carried out for 1 h, then the reaction slurry was filtered, the solid product was washed with deionized water for 3 times, and then dried to obtain the trimanganese tetraoxide product.

[0098] Example 9

[0099] Preparation of trimanganese tetraoxide with D50 of 8.0 μm:

[0100] Manganese sulfate monohydrate was weighed and an appropriate amount of deionized water was added to prepare a manganese sulfate solution with a concentration of 1.4 mol / L. Concentrated ammonia water was measured and an appropriate amount of deionized water was added to prepare an ammonia water solution with a concentration of 2.1 mol / L.

[0101] 6 L of deionized water was added to the reaction kettle and heated to 65°C, then the manganese sulfate solution was added at a flow rate of 2.2 L / h and the ammonia water solution was added at a flow rate of 0.9 L / h, while the stirring device of the reaction kettle was started (the stirring rate was set to 700 r / min) and sufficient pure oxygen was introduced into the reaction kettle to carry out the preliminary reaction, and the reaction time was 3.5 h.

[0102] After the primary reaction is completed, the stirring speed of the secondary reaction is adjusted to 600 r / min, the flow rate of the ammonia water is adjusted to 3.52 L / h, and the time length of the secondary reaction is 11 h; after the secondary reaction is completed, the addition of the manganese sulfate solution and the ammonia water solution is stopped, the stirring speed is reduced to 100 r / min, and the reaction is aged for 1 h; after the aging is completed, the reaction slurry is filtered, the solid product is washed with deionized water for 3 times, and then dried to obtain the manganese sesquioxide product.

[0103] Comparative Example 1

[0104] Preparation of manganese sesquioxide with a D50 of 8.0 μm:

[0105] The manganese sulfate monohydrate is weighed and an appropriate amount of deionized water is added to prepare a manganese sulfate solution with a concentration of 1.4 mol / L; the concentrated ammonia water is measured and an appropriate amount of deionized water is added to prepare an ammonia water solution with a concentration of 2.1 mol / L.

[0106] The prepared manganese sulfate solution and ammonia water solution are added to the reaction kettle in a 1:1 ammonia volume ratio in a single pass, the reaction temperature is 65°C, after the precipitation is completed, air is introduced through an oxygen pump, the oxidation pH is controlled at 7-8, and the oxidation time is 4 h. After the reaction is completed, the reaction slurry is filtered, the solid product is washed with deionized water for 3 times, and then dried to obtain the manganese sesquioxide product.

[0107] Comparative Example 2

[0108] Preparation of manganese sesquioxide with a D50 of 8.0 μm:

[0109] The manganese sulfate monohydrate is weighed and an appropriate amount of deionized water is added to prepare a manganese sulfate solution with a concentration of 1.4 mol / L; the concentrated ammonia water is measured and an appropriate amount of deionized water is added to prepare an ammonia water solution with a concentration of 2.1 mol / L.

[0110] The reaction kettle is added with 6 L of deionized water and heated to 65°C, then the manganese sesquioxide prepared in Example 1 is added to the reaction kettle as a crystal seed, the manganese sulfate solution is added at a flow rate of 2.2 L / h and the ammonia water solution is added at a flow rate of 2.37 L / h, at the same time, the stirring device of the reaction kettle is started (the stirring speed is set to 600 r / min) and pure oxygen is introduced into the reaction kettle to carry out the reaction, the reaction time is 11 h. After the reaction is completed, the addition of the manganese sulfate solution and the ammonia water solution is stopped, the stirring speed is reduced to 100 r / min, and the reaction is aged for 1 h; after the aging is completed, the reaction slurry is filtered, the solid product is washed with deionized water for 3 times, and then dried to obtain the manganese sesquioxide product.

[0111] The manganese sesquioxide products obtained in each example and comparative example are detected, and the performance data of each product are compared as follows:

[0112]

[0113] Application Examples

[0114] The trimanganese tetroxide prepared in each example and comparative example is mixed with lithium carbonate, wherein the lithium is excessive by 5%, and the mixed powder is pre-fired at 500 DEG C for 5h, and then calcined at 800 DEG C for 10h, to obtain iron-doped lithium manganate positive electrode material, and then the lithium manganate positive electrode material is used as raw material to prepare button batteries, and their electrochemical performances are tested as shown below:

[0115]

[0116]

[0117] In summary, according to the coupling of the primary judgment model and the secondary judgment model in combination with the ammonia water adjustment calculation model, the trimanganese tetroxide product with controllable particle size can be accurately prepared, that is, by regulating the growth process of the trimanganese tetroxide crystal, the particle size of the product is controlled and the shape is optimized, and finally the trimanganese tetroxide product with uniform and controllable particle size and good morphology is obtained, the fine control of the preparation process of Mn3O4 is realized, which is conducive to promoting and improving the utility of Mn3O4 material in lithium manganate material.

Claims

1. A process for the preparation of spheroidized battery grade trimanganese tetraoxide characterized by: The method comprises: 1) establishing a first judgment model of the flow rate of the ammonia solution to be added in a first time according to the target particle size of the product, the concentration of the manganese salt solution, the predetermined flow rate of the manganese salt solution per unit time, and the concentration of the ammonia solution, and obtaining the flow rate of the ammonia solution to be added in a first time per unit time in a first stirring reaction according to the first judgment model; adding deionized water into a reaction container and heating as a reaction bottom liquid, then adding the manganese salt solution into the reaction container under the condition of having an oxidizing agent participating, and synchronously adding the ammonia solution into the reaction container according to the obtained flow rate of the ammonia solution to be added in a first time to perform a first stirring reaction; the first judgment model is: a) when D < 10 μm, 0.2 ≤ (V2·C2) / (V1·C1) ≤ 0.8 per unit time; b) when 10 μm ≤ D ≤ 25 μm, 2.0 ≤ (V2·C2) / (V1·C1) ≤ 3.2 per unit time; wherein D is the D50 of the target product, μm; C1 is the concentration of the manganese salt solution, mol / L; C2 is the concentration of the ammonia solution, mol / L; V1 is the predetermined flow rate of the manganese salt solution, L / h; and V2 is the flow rate of the ammonia solution to be added in a first time, L / h; 2) establishing a calculation model and a second judgment model of the flow rate of the ammonia solution to be added in a second time according to the target particle size of the product, the concentration of the manganese salt solution, the predetermined flow rate of the manganese salt solution per unit time, the concentration of the ammonia solution, the flow rate of the ammonia solution to be added in a first time, the stirring rate of the first stirring reaction, and the predetermined stirring rate of the second stirring reaction, and obtaining the flow rate of the ammonia solution to be added in a second time per unit time in a second stirring reaction according to the calculation model and the second judgment model; after the first stirring reaction is completed, adjusting the real-time flow rate of the ammonia solution according to the obtained flow rate of the ammonia solution to be added in a second time after adjusting the rate, and then performing a second stirring reaction; the calculation model is: D = [1453C2V2(8846 + r2) + 48038C2V x (8102 + r1)] / [(8102 + r1)(8846 + r2)C1V1] - 0.305 (1); In formula (1), D is D50 of the target product, μm; C1 is the concentration of the manganese salt solution, mol / L; C2 is the concentration of the ammonia solution, mol / L; V1 is the predetermined flow rate of the manganese salt solution, L / h; V2 is the primary flow rate of the ammonia solution, L / h; V x is the secondary flow rate of the ammonia solution, L / h; r1 is the stirring rate during the primary stirring reaction, r / min; and r2 is the stirring rate during the secondary stirring reaction, r / min. the second judgment model is: c) 0.4 < (V2- C2) / (V1- C1) < 1.0 when D < 5 μm x • C2) / (V1- C1) < 1.0; d) when 5 μm < D < 10 μm, 1.2 < (V x (V1•C1) < 2.0; e) 2.5 < (V1-C2) / (V1-C1) < 4.0 when 10 μm < D < 25 μm in a unit of time x • C2) / (V1-C1) < 4.0; and in c), d), e): (V x • C2) / (V1• C1) - (V2• C2) / (V1• C1) ≥ 0.2; 3) after the second stirring reaction is completed, reducing the stirring rate and stopping adding the manganese salt solution and the ammonia solution until the reaction is completed; separating the solid product after the reaction, and then obtaining the battery-grade manganese tetroxide product after the solid product is sequentially subjected to washing and drying treatments.

2. The method of claim 1, wherein: In step 1), the manganese salt solution is one or more of a manganese sulfate solution, a manganese chloride solution, a manganese nitrate solution, and a manganese acetate solution; and / or In step 1), the oxidizing agent is one or more of air, oxygen, and ozone.

3. The method of claim 1, wherein: In step 1), the concentration of the manganese salt solution is 1-5 mol / L; the predetermined flow rate of the manganese salt solution is 1-10 L / h; and / or In step 1), the concentration of the ammonia solution is 1-5 mol / L.

4. The method of claim 3, wherein: In step 1), the concentration of the manganese salt solution is 1.5-4.5 mol / L; the predetermined flow rate of the manganese salt solution is 1.5-8 L / h; and / or In step 1), the concentration of the ammonia solution is 1.5-4.5 mol / L.

5. The method of claim 4, wherein: In step 1), the concentration of the manganese salt solution is 2-4 mol / L; the predetermined flow rate of the manganese salt solution is 2-6 L / h; and / or In step 1), the concentration of the ammonia solution is 2-4 mol / L.

6. The method of any one of claims 1-5, wherein: In step 1), the heating is heating the reaction bottom liquid to 45-85℃.

7. The method of claim 6, wherein: In step 1), the heating is heating the reaction bottom liquid to 50-80℃.

8. The method of claim 7, wherein: In step 1), the heating is heating the reaction bottom liquid to 55-75℃.

9. The method of any one of claims 1-5, 7-8, wherein: In step 1), the manganese salt solution and the ammonia solution are each independently preheated before being added to the reaction vessel.

10. The method of claim 9, wherein: The preheated temperature of the manganese salt solution and the ammonia solution is consistent with the temperature of the reaction bottom liquid after being heated.

11. The method of any one of claims 1-5, 7-8, 10, wherein: In step 1), the stirring rate during the first stirring reaction is not less than 400 r / min; and the time length of the first stirring reaction is 1-8 h.

12. The method of claim 11, wherein: In step 1), the stirring rate during the first stirring reaction is 600-800 r / min; and the time length of the first stirring reaction is 1-6 h.

13. The method of any one of claims 1-5, 7-8, 10, 12, wherein: In step 2), the stirring rate during the second stirring reaction is not less than 200 r / min; and the time length of the second stirring reaction is 2-24 h.

14. The method of claim 13, wherein: In step 2), the stirring rate during the second stirring reaction is 400-800 r / min; and the time length of the second stirring reaction is 3-24 h.

15. The method of any one of claims 1-5, 7-8, 10, 12, 14, wherein: In step 3), the stirring rate after the stirring rate is reduced is not higher than 500 r / min; and / or In step 3), the washing is washing with deionized water.

16. The method of claim 15, wherein: In step 3), the stirring rate after the stirring rate is reduced is 100-400 r / min; and / or In step 3), the washing is washing with deionized water 1-10 times.

17. The method of claim 15, wherein: In step 3), the stirring rate after the stirring rate is reduced is 100-200 r / min; and / or In step 3), the washing is washing with deionized water 2-8 times.

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