Preparation method of sodium manganese iron phosphate material

Abstract

A preparation method of a sodium manganese iron phosphate material, comprising the following steps: S1, configuring an ammonium phosphate solution, a manganese source solution and an ammonium persulfate solution; S2, the ammonium phosphate solution is a primer solution, and the temperature is increased to 90-100 DEG C under stirring, then the manganese source solution and the ammonium persulfate solution are synchronously added separately, and a manganese monohydrate phosphate slurry is obtained after reaction; S3, the manganese monohydrate phosphate slurry is filtered and washed, and the washed material is dried and then mixed and sheared to a target particle size; S4, a powder iron source and a powder sodium salt are added, and after mixing and shearing to a target particle size, a powder carbon source is added, and mixing and shearing are continued until a required particle size is obtained; S5, the mixed dry powder is sintered at high temperature under gas protection to obtain a sodium manganese iron phosphate material. The preparation method has the advantages of low-cost and easily available raw materials, simple process, convenient operation and low energy consumption, and the obtained sodium manganese iron phosphate material has the advantages of high crystallinity, high compaction and good electrical performance.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of new energy and sodium battery, and particularly relates to a preparation method of a sodium manganese iron phosphate material. BACKGROUND

[0002] Compared with lithium ion batteries, sodium ion batteries have the characteristics of low cost, good safety, low temperature and good rate performance, and have gradually become a research and industrial application hotspot in recent years. Although the radius of sodium ions is larger than that of lithium ions, the Stokes radius of sodium ions is smaller than that of lithium ions, so the transmission speed of sodium ions in electrolyte is faster. In sodium ion batteries, compared with other positive electrode materials such as ternary sodium materials and prussian materials, the polyanion positive electrode material has lower formation, higher safety performance and higher energy density, and becomes a mainstream material for industrial application. The sodium manganese iron phosphate material is widely concerned because it has the advantages of higher discharge voltage, higher compaction density, lower cost and environmental friendliness.

[0003] In CN109659525, sodium manganese iron fluorophosphate is prepared by electrospinning. A sodium source, an iron source, a manganese source, a phosphoric acid source, a fluorine source, a chelating agent and a high molecular polymer are mixed to form a spinning solution, and then a precursor is prepared by electrospinning. Then, a conductive high molecular polymer is added, and the mixture is stirred, filtered, washed, dried and the like to obtain a sodium manganese iron fluorophosphate product. This method needs to use organic solvents and high molecular polymers, and it is difficult to treat wastewater. The production capacity of the electrospinning method is limited, and it is difficult to meet the requirements of large-scale industrialization.

[0004] In CN117673330 A, a phosphorus source, a manganese source, an iron source I and a metal-doped compound, a reducing agent and the like are mixed to obtain a slurry containing phosphorus, iron and manganese. Then, the slurry is mixed with a sodium source, a carbon source and an iron source II by ball milling, sand milling, spray drying, pre-burning, rolling and secondary sintering to obtain a sodium manganese iron pyrophosphate product. However, this method has a long process flow and high energy consumption. SUMMARY

[0005] The application aims to solve one of the technical problems in the production and preparation process of the existing sodium battery positive electrode material. The application provides a preparation method of a sodium manganese iron phosphate material.

[0006] According to the preparation method of the sodium manganese iron phosphate material provided by the application, the following steps are included.

[0007] S1, configure an ammonium phosphate solution, a manganese source solution and a persulfate solution.

[0008] S2, the ammonium phosphate solution is added to a reaction kettle as a bottoming liquid, and is heated to 90-100 DEG C under stirring. Then, the manganese source solution and the persulfate solution are synchronously and slowly added to the reaction kettle, and a manganese monophosphate slurry is obtained after a period of reaction.

[0009] S3, the slurry is washed and dried, and then added into a high-speed mixing and shearing machine for mixing and shearing without adding any other solvent, until the target particle size is reached.

[0010] S4, the powder iron source and the powder sodium source are added into the high-speed mixing and shearing machine, and mixed and sheared for a period of time until the target particle size is reached, and then the powder carbon source is added, and worked for a period of time until the required particle size is obtained.

[0011] S5, the mixed dry powder is sintered in a roller kiln under gas protection to obtain the required manganese iron sodium phosphate product.

[0012] Preferably, the ammonium phosphate solution in step S1 is at least one of monoammonium phosphate and diammonium phosphate solution, and the manganese source solution is at least one of manganese sulfate, manganese chloride and manganese nitrate solution.

[0013] Preferably, the molar ratio of phosphorus, manganese and ammonium persulfate in the ammonium phosphate solution and the manganese source solution in step S1 is 1-1.5:1:0.5-1.0.

[0014] Preferably, the stirring speed of the reaction kettle in step S2 is 50-150 rpm, the synchronous addition time of the manganese source and ammonium persulfate is 5-8 h, and the reaction time after addition is 2-4 h.

[0015] Preferably, in step S3, the slurry is washed to a washing water conductivity of <800 us / cm, the drying inlet air temperature is 130-180℃, the drying outlet air temperature is 80-100℃, the frequency of the classifier is 20-50 Hz, the high-speed mixing speed is 500-1000 rpm, the shearing speed is 3000-5000 rpm, and the target particle size is 200-500 nm.

[0016] Preferably, in step S4, the powder iron source is at least one of iron phosphate, iron powder, red iron oxide and magnetite, the powder sodium source is at least one of sodium carbonate, sodium bicarbonate and sodium chloride, and the powder carbon source is at least one of fructose, glucose and sucrose.

[0017] Preferably, in step S4, the target particle size after adding the powder iron source and the powder sodium source is 200-300 nm, and the target particle size after adding the powder carbon source is 150-250 nm.

[0018] Preferably, in step S5, the protective gas is at least one of nitrogen, argon and helium, and preferably nitrogen. The temperature of the heating section during sintering in the roller kiln is 500-700℃, the temperature of the constant temperature section is 800-900℃, the temperature of the cooling section is 200-300℃, the total sintering time is 15-20 h, and the manganese iron sodium phosphate product is obtained after sintering.

[0019] The technical scheme of the present application firstly generates a manganese monophosphate precipitate, and then the precipitate is filtered, washed and dried, and mixed and sheared with an iron source, a sodium source and a carbon source, and the mixed and sheared material is sintered at high temperature to obtain the required manganese iron sodium phosphate product. The preparation method has the advantages of low cost, easy availability, simple process, convenient operation and low energy consumption, and the obtained manganese iron sodium phosphate material has the advantages of high crystallinity, high compaction and good electrical performance. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 XRD pattern of the manganese iron sodium phosphate material prepared in Example 3 of the present application;

[0021] Figure 2 SEM pattern of the manganese iron sodium phosphate material prepared in Example 3 of the present application. DETAILED DESCRIPTION

[0022] The technical scheme of the present application will be described clearly and completely in combination with the drawings and specific embodiments, but those skilled in the art will understand that the following described embodiments are part of the embodiments of the present application, not all the embodiments, and are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present application. The specific conditions are not specified in the embodiments, and are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not specified by the manufacturer, and are conventional products that can be purchased on the market.

[0023] <Example 1>

[0024] A preparation method of a manganese iron sodium phosphate material, comprising the following steps:

[0025] 1. Prepare 600 L of ammonium phosphate monobasic solution with a concentration of 1 mol / L, 500 L of manganese sulfate solution with a concentration of 1 mol / L, and 500 L of ammonium persulfate solution with a concentration of 0.5 mol / L.

[0026] 2. Add the ammonium phosphate monobasic solution to the reaction kettle as a primer, and stir to heat to 90-100℃ at a stirring speed of 100 rpm, then add the manganese sulfate solution and the ammonium persulfate solution to the reaction kettle simultaneously and slowly, and the addition time is 7 h. After 3 h of reaction, a manganese monophosphate slurry is obtained.

[0027] 3. The slurry is filtered and washed until the conductivity of the washing water is <800 us / cm. The washed material is dried, with the inlet air temperature being 130°C, the outlet air temperature being 80°C, and the frequency of the classifier being 20 Hz. After drying, the material is added to a high-speed mixing and shearing machine for mixing and shearing, without adding any other solvent. The high-speed mixing speed is 800 rpm, the shearing speed is 4000 rpm, and the target particle size is 300 nm.

[0028] 4. Powdered iron phosphate 22.8 kg and sodium carbonate 45 kg are added to the high-speed mixing and shearing machine. After mixing and shearing for a period of time until the particle size reaches 300 nm, powdered glucose 1.2 kg is added. After a period of time until the particle size is 250 nm.

[0029] 5. The mixed dry powder is sintered in a roller kiln under gas protection. Nitrogen is used as the protective gas. The temperature during the heating stage is 500°C, the temperature during the constant temperature stage is 850°C, and the temperature during the cooling stage is 200-300°C. The total sintering time is 17 h. The desired manganese iron sodium phosphate product is obtained.

[0030] <Example 2>

[0031] A method for preparing a manganese iron sodium phosphate material, comprising the following steps:

[0032] 1. A 1200 L solution of monammonium phosphate with a concentration of 1 mol / L, a 1000 L solution of manganese sulfate with a concentration of 1 mol / L, and a 1000 L solution of ammonium persulfate with a concentration of 0.5 mol / L are prepared.

[0033] 2. The monammonium phosphate solution is added to a reaction kettle as a primer. The solution is heated to 90-100°C while stirring at a speed of 100 rpm. The manganese sulfate solution and the ammonium persulfate solution are then added to the reaction kettle simultaneously and slowly. The addition time is 8 h. After 4 h of reaction, a manganese monophosphate slurry is obtained.

[0034] 3. The slurry is filtered and washed until the conductivity of the washing water is <800 us / cm. The washed material is dried, with the inlet air temperature being 180°C, the outlet air temperature being 100°C, and the frequency of the classifier being 50 Hz. After drying, the material is added to a high-speed mixing and shearing machine for mixing and shearing, without adding any other solvent. The high-speed mixing speed is 1000 rpm, the shearing speed is 5000 rpm, and the target particle size is 300 nm.

[0035] 4. Powdered red iron oxide 50 kg and sodium carbonate 92 kg are added to the high-speed mixing and shearing machine. After mixing and shearing for a period of time until the particle size reaches 300 nm, powdered fructose 2.4 kg is added. After a period of time until the particle size is 200 nm.

[0036] 5. The mixed dry powder is sintered at high temperature in a roller kiln under gas protection, nitrogen is used as the protection gas, the temperature of the heating section is 500-700℃, the temperature of the constant temperature section is 850℃, the temperature of the cooling section is 200-300℃, the total sintering time is 17h, and the desired sodium manganese iron phosphate product is obtained.

[0037] <Example 3>

[0038] A method for preparing a sodium manganese iron phosphate material, comprising the following steps:

[0039] 1. Prepare 3600L of ammonium phosphate monobasic solution with a concentration of 1 mol / L, 3000L of manganese sulfate solution with a concentration of 1 mol / L, and 3000L of ammonium persulfate solution with a concentration of 0.5 mol / L.

[0040] 2. Add the ammonium phosphate monobasic solution to the reaction kettle as the primer, stir and heat to 90-100℃, the stirring speed is 100rpm, then add the manganese sulfate solution and the ammonium persulfate solution to the reaction kettle simultaneously and slowly, the addition time is 5h, after 2h of reaction, a manganese phosphate monohydrate slurry is obtained.

[0041] 3. Filter and wash the slurry until the wash water conductivity is <800us / cm, dry the washed material, the inlet air temperature is 150℃, the outlet air temperature is 90℃, the classifier frequency is 35Hz, after drying, add it to a high-speed mixing shear machine for mixing and shearing, do not add any other solvent, the high-speed mixing speed is 800rpm, the shearing speed is 4000rpm, and the target particle size is 300nm.

[0042] 4. Add 151kg of powder ferric oxide and 276kg of sodium carbonate to the high-speed mixing shear machine, mix and shear for a period of time until the particle size reaches 300nm, then add 10kg of powder sucrose, and after a period of time, the particle size is 150nm.

[0043] 5. The mixed dry powder is sintered at high temperature in a roller kiln under gas protection, nitrogen is used as the protection gas, the temperature of the heating section is 500-700℃, the temperature of the constant temperature section is 850℃, the temperature of the cooling section is 200-300℃, the total sintering time is 17h, and the desired sodium manganese iron phosphate product is obtained, then take a small amount of sample for XRD and SEM detection.

[0044] The sodium manganese iron phosphate prepared in Examples 1-3 is tested for compactness, and then prepared into button cells under the same conditions, and then its electrical performance is tested under the same conditions according to the conventional method in the art. The electrical performance test results of Examples 1-3 are as follows in Table 1.

[0045] Table 1 Electrical performance comparison

[0046] As can be seen from Table 1, the compaction density of the sodium manganese iron phosphate prepared by the examples is high, close to 2.50 g / cc, the electrical performance is good, the 0.1C discharge capacity reaches 148-153 mAh / g, the prepared sodium manganese iron phosphate product has high capacity, thereby having high energy density, and the process operation is simple, having the ability of industrial production.

[0047] The above examples are only for illustrating the technical solutions and characteristics of the present application, and the purpose is to better enable the person skilled in the art to implement them, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and essence of the present application are within the protection scope of the present application, and the prior art not described in detail is the prior art.

Claims

1. A method for preparing sodium manganese iron phosphate material, characterized in that, Includes the following steps: S1. Prepare ammonium phosphate solution, manganese source solution and ammonium persulfate solution; S2. Take the ammonium phosphate solution as the base liquid, heat it to 90-100℃ with stirring, and then add the manganese source solution and ammonium persulfate solution separately and simultaneously. After the reaction, manganese phosphate monohydrate slurry is obtained. S3. Filter and wash the manganese phosphate monohydrate slurry. After drying, add the washed material to a high-speed mixing and shearing machine for mixing and shearing to the target particle size. S4. Add powdered iron source and powdered sodium source to the high-speed mixing and shearing machine. After mixing and shearing to reach the target particle size, add powdered carbon source and continue mixing and shearing until the required particle size is obtained. S5. The mixed dry powder is sintered at high temperature under gas protection to obtain the sodium manganese iron phosphate material; The ammonium phosphate solution in step S1 is at least one of monoammonium phosphate and diammonium phosphate solution, and the manganese source solution is selected from at least one of manganese sulfate, manganese chloride and manganese nitrate solution.

2. The method for preparing sodium manganese iron phosphate material according to claim 1, characterized in that, In step S1, the molar ratio of phosphorus, manganese and ammonium persulfate in the ammonium phosphate solution and manganese source solution is (1-1.5):1:(0.5-1.0).

3. The method for preparing sodium manganese iron phosphate material according to claim 1, characterized in that, Step S2 is carried out in a reactor with a stirring speed of 50-150 rpm. The manganese source solution and ammonium persulfate solution are added simultaneously over a period of 5-8 hours, and the reaction time after addition is 2-4 hours.

4. The method for preparing a sodium manganese iron phosphate material according to claim 1, characterized in that, In step S3, the slurry is washed until the conductivity of the wash water is <800 μS / cm. During drying, the inlet air temperature is 130-180℃, the outlet air temperature is 80-100℃, the classifier frequency is 20-50Hz, the high-speed mixing speed is 500-1000 rpm, the shearing speed is 3000-5000 rpm, and the target particle size is 200-500 nm.

5. The method for preparing a sodium manganese iron phosphate material according to claim 1, characterized in that, In step S4, the iron source of the powder is at least one of iron phosphate, iron powder, iron oxide red, and iron(II,III) oxide; the sodium source of the powder is at least one of sodium carbonate, sodium bicarbonate, and sodium chloride; and the carbon source of the powder is at least one of fructose, glucose, and sucrose.

6. The method for preparing a sodium manganese iron phosphate material according to claim 1, characterized in that, The target particle size after adding the powdered iron source and powdered sodium source in step S4 is 200-300 nm, and the target particle size after adding the powdered carbon source is 150-250 nm.

7. The method for preparing a sodium manganese iron phosphate material according to claim 1, characterized in that, The protective gas in step S5 is at least one of nitrogen, argon, and helium.

8. The method for preparing a sodium manganese iron phosphate material according to claim 1, characterized in that, Step S5 involves high-temperature sintering in a roller kiln. During sintering, the temperature in the heating section is 500-700℃, the temperature in the constant temperature section is 800-900℃, and the temperature in the cooling section is 200-300℃. The total sintering time is 15-20 hours. After sintering, sodium manganese iron phosphate is obtained.

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