A method for preparing micro / nano spherical manganese tetroxide material

Abstract

This invention discloses a method for preparing micro / nano spherical manganese tetroxide materials, relating to the technical field of manganese tetroxide materials for soft magnetic applications. The method involves adding bottom water, ammonium salt, surfactant, and self-templating agent to a reaction vessel, followed by heating and stirring. A manganese salt solution is pumped into the reaction vessel simultaneously with an ammonia solution, maintaining the pH of the reaction system at 8-9 throughout the manganese salt addition process. The ammonia solution is then continuously pumped in, maintaining the reaction system at a pH of 6-12 for aging. The aged material is filtered, washed, and a manganese tetroxide slurry is prepared with additives. The slurry is then spray-dried to obtain primary particles of 50-150 nm, secondary agglomerates forming spherical shapes, and a tap density greater than 2.1 g / cm³. 3 The invention relates to a micro-nano spherical structure manganese tetroxide material. The invention employs a liquid-phase precipitation oxidation method, which is simple to operate and easy to industrialize. Manganese tetroxide exhibits excellent grindability and dispersibility. Furthermore, with the addition of additives and process improvements, the product achieves a micro-nano spherical structure that meets the requirements of battery materials.

Description

Technical Field

[0001] This invention relates to the field of manganese tetroxide materials for soft magnetic applications, specifically a method for preparing a micro / nano spherical structured manganese tetroxide material. Background Technology

[0002] Manganese tetroxide (MnO) can be mixed with iron and zinc oxides in a specific ratio, molded, and sintered to produce high-performance soft magnetic ferrite materials. Currently, most MnO manufacturers in my country use manganese salt precipitation oxidation and metallic manganese suspension oxidation processes, as disclosed in patents CN1252385A, CN1252386A, and CN103058280A. China is the world's largest producer and supplier of MnO, with an annual output of up to 110,000 tons. With the advancement of electrification, the market demand for soft magnetic ferrites is expected to expand further in the future.

[0003] The new energy battery market has experienced rapid development. Ternary lithium batteries, nickel-manganese lithium batteries, lithium manganese oxide batteries, lithium manganese iron phosphate batteries, and the nascent sodium-ion batteries all utilize manganese oxides. Battery-grade manganese tetroxide (MnO) has become the preferred cathode material for batteries due to its high purity and high stability. Currently, more than half of battery materials are produced using high-temperature solid-state methods. This requires both the primary particle size of MnO to be as small as possible and the secondary agglomeration particles to have a spherical structure to ensure the energy density of the battery material. Therefore, preparing a micro / nano spherical structure of MnO aligns with the national development direction.

[0004] In the high-end field of manganese tetroxide (MTO) materials, Tosoh Corporation of Japan remains the leader. Comparatively, Tosoh's MTO products exhibit a generally spherical morphology with a primary particle size of 50-150 nm. This micro-nano spherical structure gives their MTO products exceptionally good grindability and dispersibility. Meanwhile, domestic products of the same period have a primary particle size of approximately 200-500 nm. We believe this technological gap is the fundamental reason for the difference in grindability and dispersibility between the two companies' products.

[0005] Currently, liquid-phase preparation methods for micro / nano materials mainly include hydrothermal methods and sol-gel methods. However, these methods are limited by manufacturing costs and are difficult to scale up for industrial production. Patent application CN113603145A, entitled "A Method for Preparing Micro / Nano Manganese Tetraoxide from Manganese Sulfate Solution," discloses a precipitation oxidation method for preparing micro / nano manganese tetraoxide. While this method is advantageous for large-scale production, it only yields products with a D50 < 2 μm. As can be seen from Figures 3, 5, and 7 in the specification, the smallest size is still above 200 nm. Therefore, there is an urgent need for a method to prepare micro / nano spherical manganese tetraoxide materials to address this problem. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing micro / nano spherical manganese tetroxide materials, so as to solve the problem that existing methods suitable for large-scale production of manganese tetroxide materials cannot meet the requirements of battery materials.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a micro / nano spherical manganese tetroxide material, comprising the following specific steps:

[0008] S1 Place the reaction vessel in a water bath, add a certain amount of bottom water to the reaction vessel, and simultaneously add a certain amount of ammonium salt, surfactant and self-templating agent. Turn on the stirring and maintain a certain speed until the bottom water temperature reaches the set value.

[0009] Once the S2 temperature reaches the set value, a certain amount and concentration of manganese salt solution is pumped into the reaction vessel at a certain feeding rate using a peristaltic pump. At the same time, a certain concentration of ammonia solution is pumped into the reaction vessel using another peristaltic pump. During the manganese salt feeding process, the pH value of the reaction system is maintained at 8-9.

[0010] After the S3 manganese salt feeding process is completed, continue to pump in ammonia solution to maintain the reaction system at pH 6-12 for aging;

[0011] S4 filters the aged material and washes it several times with deionized water. A manganese tetroxide slurry is prepared according to a specific solid-liquid ratio, and a certain amount of additives are added. The slurry is then spray-dried at a specific temperature to obtain primary particles of 50-150 nm, secondary agglomerates forming spherical shapes, and a tap density greater than 2.1 g / cm³. 3 Micro-nano spherical structure manganese tetroxide material.

[0012] Preferably, in step S1, the ammonium salt is ammonium sulfate, the surfactant is stearic acid, and the self-templating agent is hexadecyltrimethylammonium bromide; in step S2, the manganese salt is battery-grade high-purity manganese sulfate; and in step S4, the additive is cellulose and / or chitosan.

[0013] In the preferred embodiment described above, the concentration of the manganese salt solution is 0.2M-0.5M, the total amount added is 300-1000ml, the bottom water is 100-500ml of deionized water, the ammonium salt is 1-50g, the surfactant is 0.1-10g, and the self-templating agent is 0.01-2g.

[0014] Preferably, in step S1 above, the stirring speed is 300-700 rpm and the bottom water temperature is set to 40-80℃.

[0015] Preferably, in step S2 above, the feeding rate of the manganese salt solution is 0.1-2 ml / min, and the concentration of the ammonia solution used is 5%-15%.

[0016] Preferably, in step S3 above, the aging time is 0.5h-15h.

[0017] Preferably, in step S4 above, the number of washing cycles is 1-5 times, and the amount of deionized water used is 1L-3L.

[0018] Preferably, in step S4 above, the solid-liquid ratio of the manganese tetroxide slurry is 40%, the mass of the additive is 1%-5% of the solid content of the slurry, and the spray drying temperature is 90℃-150℃.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. The preparation method of this micro-nano spherical manganese tetroxide material adopts the liquid phase precipitation oxidation method, which is simple and easy to operate and easy to industrialize.

[0021] 2. The preparation method of this micro-nano spherical structure manganese tetroxide material prepares manganese tetroxide material under the condition of maintaining the reaction system at a high pH value. The primary particle size of the obtained material is between 50-150 nm. The grindability and dispersibility of the material are greatly improved on the basis of the existing method. At the same time, it is also beneficial to overcome the fundamental problem of high impurity content faced by the manganese salt method in preparing manganese tetroxide material.

[0022] 3. The preparation method of the micro-nano spherical structure manganese tetroxide material, by controlling the secondary particle size of manganese tetroxide powder material through additives and preparation process, can prepare micro-nano spherical structure manganese tetroxide material that meets the requirements of battery materials. Attached Figure Description

[0023] Figure 1 This is a SEM image of manganese tetroxide prepared in Example 1 of this invention.

[0024] Figure 2 This is a SEM image of manganese tetroxide prepared in Comparative Example 1. Detailed Implementation

[0025] A method for preparing a micro / nano spherical manganese tetroxide material includes the following specific steps:

[0026] S1 Place the reaction vessel in a water bath, add a certain amount of bottom water to the reaction vessel, and simultaneously add a certain amount of ammonium salt, surfactant and self-templating agent. Turn on the stirring and maintain a certain speed (e.g. 300-700 rpm). Wait until the bottom water temperature reaches the set value, preferably 40-80℃.

[0027] Once the S2 temperature reaches the set value, a certain amount and concentration of manganese salt solution is pumped into the reaction vessel at a certain feeding rate using a peristaltic pump. At the same time, a certain concentration of ammonia solution is pumped into the reaction vessel using another peristaltic pump. During the manganese salt feeding process, the pH value of the reaction system is maintained at 8-9.

[0028] After the S3 manganese salt feeding process is completed, continue to pump in ammonia solution to maintain the reaction system at pH 6-12 for aging. The aging time can be 0.5h-15h.

[0029] S4 filters the aged material and washes it several times with deionized water. A manganese tetroxide slurry is then prepared with additives (to improve the micro / nano spherical structure of the product). The product is then spray-dried. For reference, the solid-liquid ratio of the manganese tetroxide slurry can be 40%, the additive mass is 1%-5% of the slurry's solid content, and the spray-drying temperature is 90℃-150℃. The resulting product has primary particles between 50-150 nm, secondary agglomeration into spherical shapes, and a tap density greater than 2.1 g / cm³. 3 Micro-nano spherical structure manganese tetroxide material.

[0030] For reference, in step S1, the ammonium salt is ammonium sulfate, the surfactant is stearic acid, and the self-templating agent is hexadecyltrimethylammonium bromide; in step S2, the manganese salt is battery-grade high-purity manganese sulfate; and in step S4, the additives are cellulose and / or chitosan.

[0031] In a preferred embodiment, the concentration of the manganese salt solution is 0.2M-0.5M, the total amount added is 300-1000ml, the bottom water is 100-500ml of deionized water, the ammonium salt is 1-50g, the surfactant is 0.1-10g, and the self-templating agent is 0.01-2g. The above values ​​can be increased or decreased proportionally. The above proportions are for reference only. The number of washing cycles in step S4 can be 1-5 times, and the amount of deionized water used is 1L-3L.

[0032] In a preferred embodiment, the feeding rate of the manganese salt solution in step S2 can be 0.1-2 ml / min, and the concentration of the ammonia solution can be selected from 5% to 15%.

[0033] Example 1: A method for preparing a micro / nano spherical manganese tetroxide material, the preparation method comprising the following steps:

[0034] (1) Place the reaction vessel in a water bath, add 300ml of bottom water to the reaction vessel, and simultaneously add 30g of ammonium sulfate, 0.5g of stearic acid and 1g of hexadecyltrimethylammonium bromide. Turn on the stirring and keep the speed at 600rpm. After the bottom water reaches 60℃, start step (2).

[0035] (2) 400 ml of 0.3 M manganese salt solution was pumped into the reaction vessel described in (1) at a feeding rate of 3 ml / min using a peristaltic pump, and a 10% ammonia solution was pumped in using another peristaltic pump to maintain the pH value of the reaction system in the range of 8-8.5.

[0036] (3) After the manganese salt feeding process in step (2) is completed, continue stirring and continue pumping in ammonia solution to maintain the pH value of the reaction system in the range of 7-7.5 for aging for 12 hours;

[0037] (4) After steps (3) are completed, the material obtained in (3) is filtered and washed three times with a certain amount of deionized water. Then, a manganese tetroxide slurry is prepared according to a solid-liquid ratio of 40% and cellulose with a solid content of 3% is added. The slurry is then spray-dried at 120°C to obtain a primary particle size of 50-150 nm, a secondary agglomeration into spherical shape, and a tap density greater than 2.1 g / cm³. 3 Micro-nano spherical structure manganese tetroxide material.

[0038] The SEM image of the manganese tetroxide product prepared in Example 1 is shown below. Figure 1 .

[0039] Example 2: A method for preparing a micro / nano spherical manganese tetroxide material, the preparation method comprising the following steps:

[0040] (1) Place the reaction vessel in a water bath, add 200ml of bottom water to the reaction vessel, and simultaneously add 25g of ammonium sulfate, 0.5g of stearic acid and 1g of hexadecyltrimethylammonium bromide. Turn on the stirring and keep the speed at 600rpm. After the bottom water reaches 60℃, start step (2).

[0041] (2) 500 ml of 0.5 M manganese salt solution was pumped into the reaction vessel described in (1) at a feeding rate of 5 ml / min using a peristaltic pump, and a 15% ammonia solution was pumped in using another peristaltic pump to maintain the pH value of the reaction system in the range of 8.5-9.

[0042] (3) After the manganese salt feeding process in step (2) is completed, continue stirring and continue pumping in ammonia solution to maintain the pH value of the reaction system in the range of 7-7.5 for aging for 12 hours;

[0043] (4) After steps (3) are completed, the material obtained in (3) is filtered and washed three times with a certain amount of deionized water. Then, a manganese tetroxide slurry is prepared according to a solid-liquid ratio of 40% and chitin with a solid content of 2% is added. The slurry is then spray-dried at 150°C to obtain a primary particle size of 50-150 nm, a secondary agglomeration into spherical shape, and a tap density greater than 2.1 g / cm³. 3 Micro-nano spherical structure manganese tetroxide material.

[0044] Example 3: A method for preparing a micro / nano spherical manganese tetroxide material, the preparation method comprising the following steps:

[0045] (1) Place the reaction vessel in a water bath, add 300ml of bottom water to the reaction vessel, and simultaneously add 15g of ammonium sulfate, 1g of stearic acid and 0.5g of cetyltrimethylammonium bromide. Turn on the stirring and keep the speed at 500rpm. After the bottom water reaches 70℃, start step (2).

[0046] (2) 1000 ml of 0.5 M manganese salt solution is pumped into the reaction vessel described in (1) at a feeding rate of 10 ml / min using a peristaltic pump, and a 15% ammonia solution is pumped in using another peristaltic pump to maintain the pH value of the reaction system in the range of 8.5-9.

[0047] (3) After the manganese salt feeding process in step (2) is completed, continue stirring and continue pumping in ammonia solution to maintain the pH value of the reaction system in the range of 7.5-8 and age for 10 hours;

[0048] (4) After steps (3) are completed, the material obtained in (3) is filtered and washed three times with a certain amount of deionized water. Then, a manganese tetroxide slurry is prepared according to a solid-liquid ratio of 40%, and chitin with a solid content of 1% and cellulose with a solid content of 2% are added. The slurry is then spray-dried at 150°C to obtain a primary particle size of 50-150 nm, a secondary agglomeration into spherical shape, and a tap density greater than 2.1 g / cm³. 3 Micro-nano spherical structure manganese tetroxide material.

[0049] Comparative Example 1:

[0050] (1) Take 1 ton of electrolytic manganese metal flakes and add them to a horizontal ball mill. Wet ball mill for 80 min to obtain manganese slurry with a mesh size of less than 80.

[0051] (2) First towards 10 m 3 Add 1 m to the reaction vessel 3Deionized water was added, and then 30 kg of ammonium chloride was added to the reactor as a catalyst. The prepared manganese slurry was then added to the reactor, and deionized water was added to dilute the manganese slurry to obtain a reaction slurry with a manganese mass percentage concentration of 30%. The stirring impeller in the reactor was started, and the frequency converter was adjusted to set the stirring impeller speed to 200 r / min. Simultaneously, air was introduced into the reactor, and the air flow rate was adjusted to 100 m³ / min. 3 / h,

[0052] (3) Continue the reaction until the pH value of the slurry drops to 6.5, and then the manganese tetroxide slurry is obtained;

[0053] (4) Put the manganese tetroxide slurry into a mixer, add deionized water and stir for 30 minutes. Then wash and filter it by vacuum filtration and finally dry it to obtain the manganese tetroxide product.

[0054] The SEM image of the manganese tetroxide product prepared in Comparative Example 1 is shown below. Figure 2 .

[0055] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

[0056] Any aspects of this invention not described in detail are well-known to those skilled in the art.

Claims

1. A method for preparing a micro / nano spherical manganese tetroxide material, characterized in that, The specific steps include the following: S1 Place the reaction vessel in a water bath, add a certain amount of bottom water to the reaction vessel, and simultaneously add a certain amount of ammonium salt, surfactant and self-templating agent. Turn on the stirring and maintain a certain speed until the bottom water temperature reaches the set value. Once the S2 temperature reaches the set value, a certain amount and concentration of manganese salt solution is pumped into the reaction vessel at a certain feeding rate using a peristaltic pump. At the same time, a certain concentration of ammonia solution is pumped into the reaction vessel using another peristaltic pump. During the manganese salt feeding process, the pH value of the reaction system is maintained at 8-9. After the S3 manganese salt feeding process is completed, continue to pump in ammonia solution to maintain the reaction system at pH 6-12 for aging; S4 filters the aged material and washes it several times with deionized water. A manganese tetroxide slurry is prepared according to a specific solid-liquid ratio, and a certain amount of additives (cellulose and / or chitosan) are added. The mixture is then spray-dried at a specific temperature to obtain primary particles of 50-150 nm, secondary agglomerates forming spherical shapes, and a tap density greater than 2.1 g / cm³. 3 Micro-nano spherical structure manganese tetroxide material.

2. The method for preparing a micro / nano spherical manganese tetroxide material according to claim 1, characterized in that: In step S1, the ammonium salt is ammonium sulfate, the surfactant is stearic acid, and the self-templating agent is hexadecyltrimethylammonium bromide; in step S2, the manganese salt is battery-grade high-purity manganese sulfate.

3. The method for preparing a micro / nano spherical manganese tetroxide material according to claim 2, characterized in that: The concentration of the manganese salt solution is 0.2M-0.5M, the total amount added is 300-1000ml, the bottom water is 100-500ml of deionized water, the ammonium salt is 1-50g, the surfactant is 0.1-10g, and the self-templating agent is 0.01-2g.

4. The method for preparing a micro / nano spherical manganese tetroxide material according to claim 1, characterized in that: In step S1, the stirring speed is 300-700 rpm, and the bottom water temperature is set to 40-80℃.

5. The method for preparing a micro / nano spherical manganese tetroxide material according to claim 1, characterized in that: In step S2, the manganese salt solution is fed at a rate of 0.1-2 ml / min, and the concentration of the ammonia solution used is 5%-15%.

6. The method for preparing a micro / nano spherical manganese tetroxide material according to claim 1, characterized in that: In step S3, the aging time is 0.5h-15h.

7. The method for preparing a micro / nano spherical manganese tetroxide material according to claim 3, characterized in that: In step S4, the number of washing cycles is 1-5, and the amount of deionized water used is 1L-3L.

8. The method for preparing a micro / nano spherical manganese tetroxide material according to claim 1, characterized in that: In step S4, the solid-liquid ratio of the manganese tetroxide slurry is 40%, the mass of the additive is 1%-5% of the solid content of the slurry, and the spray drying temperature is 90℃-150℃.

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