Preparation method of sodium ferromanganese vanadium phosphate material of sodium battery positive electrode

Abstract

The invention discloses a preparation method of a sodium ferromanganese vanadium phosphate material of a sodium battery positive electrode. The preparation method comprises the following steps: S1, preparing a hydrophosphate solution and a manganous salt solution; and S2, adding the hydrophosphate solution into the manganous salt solution, and reacting to obtain the manganous hydrogen phosphate crystal nucleus slurry. And S3, filtering and washing the manganese hydrogen phosphate crystal nucleus slurry, adding water into the manganese hydrogen phosphate material to prepare slurry, heating to 85-95 DEG C, respectively adding a ferrous source and a phosphorus salt solution, and reacting to obtain the manganese iron hydrogen phosphate slurry. And S4, filtering, washing and drying the iron manganese hydrogen phosphate slurry, adding water into the dried slurry to prepare slurry, adding phosphoric acid, heating to 90-100 DEG C, reacting to obtain an iron manganese phosphate compound precipitate, and filtering, washing and drying the precipitate to obtain an iron manganese phosphate material. The sodium manganese iron vanadium phosphate product is prepared by adopting a coprecipitation method and high-temperature sintering, and the method has the advantages of short process flow, simple process, only one-time sintering, low energy consumption and the like.

Description

Technical Field

[0001] The present invention relates to the technical fields of new energy and sodium battery technologies, and particularly relates to a preparation method of a sodium-ion battery cathode material sodium iron manganese vanadium phosphate. Background Art

[0002] Compared with lithium-ion batteries, sodium-ion batteries have attracted wide attention due to their environmental friendliness, high safety, low cost, good low-temperature and rate performance. Poly-anionic sodium-ion battery cathode materials, especially sodium-ion battery cathode materials based on phosphate roots, have gradually become the focus of attention due to their low cost, short process flow, relatively high energy density, safety and non-toxicity. In sodium iron manganese vanadium phosphate materials, the introduction of manganese element increases the working voltage, thus improving the energy density of sodium batteries; the addition of iron element reduces the band gap width of the material, improves the electronic conductivity of the material, and also improves the stability of the material. The addition of vanadium element increases the unit cell volume, making the sodium-ion channels larger and improving the ionic conductivity of sodium ions; in addition, the introduction of iron and vanadium elements also inhibits the manganese dissolution, alleviates the Jahn-Teller effect, and improves the rate performance and cycle life of sodium-ion batteries. CN117673330A discloses a preparation method of a sodium manganese iron pyrophosphate cathode material. In this patent application, a phosphorus source, a manganese source, an iron source I, a vanadium source, etc. are first pre-reacted with a reducing agent (ascorbic acid, lactic acid, etc.) to obtain a phosphorus-manganese-containing slurry. The obtained slurry is then mixed with a sodium source, a carbon source, and an iron source II through processes such as dispersion ball milling, sand milling, spray drying, followed by primary sintering, rolling, secondary sintering, and crushing to obtain vanadium-doped sodium manganese iron pyrophosphate. The preparation process of this patent application is long, the preparation process is complex, and it requires two sinterings, with high energy consumption, which is not conducive to industrialization and industrial production. Moreover, the discharge capacity of the prepared vanadium-doped sodium manganese iron pyrophosphate product is relatively low, only 90-110 mAh / g. CN109659525A discloses a method for preparing a sodium manganese iron fluorophosphate composite cathode material. In this patent application, a spinning solution formed by a sodium source, an iron source, a manganese source, a phosphate source, a fluorine source, a chelating agent, and a polymer is used as the outer axis, and an oil-based spinning solution is used as the inner axis for coaxial electrospinning. The oil phase is extracted and removed, and then dried to obtain a hollow nanofiber precursor, which is heat-treated in a non-oxidizing atmosphere and cooled to obtain carbon-coated sodium manganese iron fluorophosphate. However, this method requires the use of chelating agents and polymers, etc. In addition, the fluorine source has strong corrosivity to equipment and pipelines, and the electrospinning production capacity is low, making it difficult to achieve industrialization and industrial production. Summary of the Invention

[0003] The object of the present invention is to solve one of the technical problems existing in the production and preparation process of existing sodium-ion battery cathode materials. The present invention proposes a preparation method of a sodium-ion battery cathode material sodium iron manganese vanadium phosphate.

[0004] A preparation method of sodium manganese iron vanadium phosphate as a sodium battery cathode material, comprising the following steps: S1. Prepare a hydrogen phosphate solution and a manganese salt solution.

[0005] S2. Add the hydrogen phosphate solution to a reaction kettle as a bottoming solution, and then slowly add the manganese salt solution to the reaction kettle at room temperature. After reacting for a period of time, a hydrogen manganese phosphate crystal nucleus slurry is obtained.

[0006] S3. Filter and wash the hydrogen manganese phosphate crystal nucleus slurry. Add the washed hydrogen manganese phosphate material to water to make a slurry and add it to the reaction kettle. When the temperature is raised to 85-95 °C, add an iron source and a phosphate solution to the reaction kettle respectively and simultaneously. After reacting for a period of time, a hydrogen iron manganese phosphate slurry is obtained.

[0007] S4. Filter, wash and dry the hydrogen iron manganese phosphate slurry. Add water to the dried slurry to make a slurry, add phosphoric acid, and react for a period of time after the temperature is raised to 90-100 °C to obtain a ferric manganese phosphate compound precipitate. The precipitate is filtered, washed and dried to obtain a ferric manganese phosphate material.

[0008] S5. Add the ferric manganese phosphate material to a stirring crusher for stirring and crushing. After crushing to a certain particle size, add a vanadium source, a sodium source and a carbon source, without adding water or any other solvent, and crush to the target particle size.

[0009] S6. Sinter the obtained dry powder at high temperature in a rotary kiln to obtain the required sodium manganese iron vanadium phosphate product.

[0010] Preferably, in step S1, the hydrogen phosphate is at least one of sodium monohydrogen phosphate and sodium dihydrogen phosphate; the manganese salt is selected from at least one of manganese sulfate and manganese chloride.

[0011] Preferably, in step S2, the stirring speed of the reaction kettle is 50-200 rpm, the addition time of the manganese salt solution is 5-8 h, the reaction time after the manganese salt solution is added is 30-60 min, and the molar ratio of manganese to phosphorus in the manganese salt and the hydrogen phosphate is 1:1.

[0012] Preferably, in step S3, the iron source is at least one of ferrous sulfate, ferrous chloride and ferrous nitrate; the phosphate is at least one of ammonium monophosphate and ammonium dihydrogen phosphate, and the molar ratio of iron in the iron source to iron, manganese and phosphorus in the manganese salt in S1 and the phosphate in S3 is 1:8:1.

[0013] Preferably, in step S3, the conductivity of the washing water during slurry washing is <1000 us / cm, the stirring speed of the reaction kettle is 50-200 rpm, the addition time of the iron source and the phosphate solution is 5-8 h, and the reaction time after adding the iron source and the phosphate solution is 3-5 h.

[0014] Preferably, during the slurry washing in step S4, the conductivity of the washing water is < 800 us / cm, the drying temperature is 120 °C, the drying time is 3 h, the phosphoric acid is phosphoric acid with a mass concentration of 40 - 85%, the stirring speed of the reaction kettle is 50 - 200 rpm, the addition time of the phosphoric acid is 5 - 8 h, and the reaction time after adding the phosphoric acid is 3 - 5 h.

[0015] Preferably, the vanadium source in step S5 is at least one of vanadyl sulfate, vanadium pentoxide, and vanadium chloride; the sodium source is at least one of sodium carbonate, sodium phosphate, monosodium phosphate, and disodium phosphate; the carbon source is at least one of fructose, sucrose, and glucose.

[0016] Preferably, in step S5, the stirring speed is 500 - 1000 rpm, the speed of the crushing disk is 2000 - 5000 rpm, the particle size of the manganese iron phosphate crushed is 100 - 300 nm, the particle size after adding the vanadium source, sodium source, and carbon source is 150 - 450 nm, and the molar ratio of the sodium source to vanadium, manganese in S1, ferrous in S3, and phosphorus in the phosphorus source is 1:0.1:0.8:0.1:1.

[0017] Preferably, in step S6, the rotation frequency of the rotary kiln is 30 Hz, the temperature in the heating section is 150 - 600 °C, the temperature in the constant temperature section is 800 - 1000 °C, the temperature in the cooling section is 200 - 300 °C, and the sintering time is 12 - 20 h.

[0018] Advantages of the present invention: The present invention uses the co - precipitation method and high - temperature sintering to prepare sodium vanadium manganese iron phosphate products, which have the advantages of short process flow, simple process, only requiring one sintering, low energy consumption, etc. Moreover, the prepared sodium vanadium manganese iron phosphate products have characteristics such as high tap density, high discharge capacity, and high energy density. Description of the Drawings

[0019] Figure 1 XRD pattern of the sodium vanadium manganese iron phosphate material prepared in Example 3 of the present invention; Figure 2 SEM image of the sodium vanadium manganese iron phosphate material prepared in Example 3 of the present invention. Detailed Description of the Invention

[0020] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the following described embodiments are some embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0021] <Example 1> 1. Prepare 500 L of a sodium dihydrogen phosphate solution with a concentration of 1.2 mol / L and 400 L of a manganese sulfate solution with a concentration of 1.5 mol / L.

[0022] 2. Add the sodium dihydrogen phosphate solution to the reaction kettle as a bottoming liquid, with the stirring speed of the reaction kettle being 100 rpm. Then, slowly add the manganese sulfate solution to the reaction kettle at room temperature over a period of 6 h. After adding, react for 30 min to obtain a manganese hydrogen phosphate crystal nucleus slurry.

[0023] 3. Filter and wash the slurry. Add the washed manganese hydrogen phosphate material to water to make a slurry and then add it to the reaction kettle. When the temperature is raised to 85 - 95 °C, simultaneously add 75 L of a 1.0 mol / L ferrous sulfate solution and 50 L of a 1.5 mol / L ammonium dihydrogen phosphate solution to the reaction kettle over a period of 5 h. After reacting for 3 h, obtain a manganese iron hydrogen phosphate slurry.

[0024] 4. Filter and wash the slurry until the conductivity of the washing water is < 600 us / cm, and dry it at 120 °C for 3 h. Then, add water to the dried slurry to make a slurry, add 50 kg of 40% phosphoric acid, with the addition time of phosphoric acid being 5 h. After raising the temperature to 90 - 100 °C, react for 3 h to obtain a manganese iron phosphate compound precipitate. The precipitate is filtered, washed, and dried to obtain a manganese iron phosphate material.

[0025] 5. Add the manganese iron phosphate material to a stirring crusher for stirring and crushing. The stirring speed is 500 - 1000 rpm, the speed of the crushing disk is 2000 - 5000 rpm, the crushing particle size of the manganese iron phosphate is 150 nm. Add 1.5 kg of vanadium pentoxide, 105 kg of sodium carbonate, and 5.5 kg of sucrose, without adding water or any other solvent, and crush to a particle size of 200 nm.

[0026] 6. Carry out high-temperature sintering of the obtained dry powder in a rotary kiln. The rotation frequency of the rotary kiln is 30 Hz, the temperature in the heating section is 150 - 600 °C, the temperature in the constant temperature section is 850 °C, the temperature in the cooling section is 200 - 300 °C, and the sintering time is 17 h to obtain the required sodium manganese iron vanadium phosphate product.

[0027] <Example 2> 1. Prepare 1000 L of a sodium dihydrogen phosphate solution with a concentration of 1.2 mol / L and 800 L of a manganese sulfate solution with a concentration of 1.5 mol / L.

[0028] 2. Add the sodium dihydrogen phosphate solution to the reaction kettle as the base solution. The stirring speed of the reaction kettle is 100 rpm. Then, slowly add the manganese sulfate solution to the reaction kettle at room temperature over 8 h. After addition, react for 60 min to obtain a manganese hydrogen phosphate crystal nucleus slurry.

[0029] 3. Filter and wash the slurry. Add the washed manganese hydrogen phosphate material to the reaction kettle after making it into a slurry with water. When the temperature is raised to 85 - 95 °C, add 100 L of a ferrous sulfate solution with a concentration of 1.4 mol / L and 140 L of an ammonium dihydrogen phosphate solution with a concentration of 1.0 mol / L to the reaction kettle simultaneously over 8 h. After reacting for 5 h, obtain a ferric manganese hydrogen phosphate slurry.

[0030] 4. Filter and wash the slurry until the conductivity of the washing water is < 600 us / cm. Dry at 120 °C for 3 h. Add water to the dried slurry to make it into a slurry again, add 100 kg of 40% phosphoric acid. The addition time of phosphoric acid is 8 h. After raising the temperature to 90 - 100 °C, react for 5 h to obtain a ferric manganese phosphate compound precipitate. Filter, wash, and dry the precipitate to obtain a ferric manganese phosphate material.

[0031] 5. Add the ferric manganese phosphate material to a stirring crusher for stirring and crushing. The stirring speed is 500 - 1000 rpm, the speed of the crushing disc is 2000 - 5000 rpm, the crushing particle size of ferric manganese phosphate is 150 nm. Add 3 kg of vanadium pentoxide, 210 kg of sodium carbonate, and 11 kg of sucrose. Do not add water or any other solvent, and crush to a particle size of 200 nm.

[0032] 6. Sinter the obtained dry powder in a rotary kiln. The rotation frequency of the rotary kiln is 30 Hz. The temperature in the heating section is 150 - 600 °C, the temperature in the constant temperature section is 850 °C, the temperature in the cooling section is 200 - 300 °C, and the sintering time is 17 h to obtain the required sodium ferric manganese vanadium phosphate product.

[0033] <Example 3> 1. Prepare 2500 L of a sodium dihydrogen phosphate solution with a concentration of 1.2 mol / L and 2000 L of a manganese sulfate solution with a concentration of 1.5 mol / L.

[0034] 2. Add the sodium dihydrogen phosphate solution to the reaction kettle as the base solution. The stirring speed of the reaction kettle is 100 rpm. Then, slowly add the manganese sulfate solution to the reaction kettle at room temperature over 5 h. After addition, react for 30 min to obtain a manganese hydrogen phosphate crystal nucleus slurry.

[0035] 3. Slurry filtration and washing: The washed manganese hydrogen phosphate material is made into a slurry by adding water and added to the reaction kettle. When the temperature is raised to 85 - 95 °C, 250 L of 1.4 mol / L ferrous sulfate solution and 350 L of 1.0 mol / L ammonium dihydrogen phosphate solution are simultaneously added to the reaction kettle. The addition time is 5 h. After reacting for 3 h, manganese iron hydrogen phosphate slurry is obtained.

[0036] 4. The slurry is filtered and washed until the conductivity of the washing water < 600 us / cm, dried at 120 °C for 3 h. The dried slurry is made into a slurry again by adding water, 250 kg of 40% phosphoric acid is added, the addition time of phosphoric acid is 6 h, and after the temperature is raised to 90 - 100 °C, it reacts for 5 h to obtain manganese iron phosphate compound precipitate. The precipitate is filtered, washed and dried to obtain manganese iron phosphate material.

[0037] 5. Add the manganese iron phosphate material to a stirring crusher for stirring and crushing. The stirring speed is 500 - 1000 rpm, the speed of the crushing disc is 2000 - 5000 rpm, the crushing particle size of manganese iron phosphate is 150 nm, 7.5 kg of vanadium pentoxide, 525 kg of sodium carbonate and 27.5 kg of sucrose are added, without adding water or any other solvent, and crushed to a particle size of 200 nm.

[0038] 6. The obtained dry powder is subjected to high-temperature sintering in a rotary kiln. The rotation frequency of the rotary kiln is 30 Hz, the temperature in the heating section is 150 - 600 °C, the temperature in the constant temperature section is 850 °C, the temperature in the cooling section is 200 - 300 °C, and the sintering time is 17 h to obtain the required sodium vanadium manganese iron phosphate product.

[0039] <Comparative Example 1> Steps 1 - 3 of Comparative Example 1 are exactly the same as those of Example 3. Step 4 is: The manganese iron hydrogen phosphate slurry is filtered and washed until the conductivity of the washing water < 600 us / cm, dried at 120 °C for 3 h to obtain manganese iron hydrogen phosphate material. Then, the manganese iron hydrogen phosphate material is used to replace the manganese iron phosphate material in Step 5, and the subsequent steps are the same as those of Example 3.

[0040] <Comparative Example 2> Steps 1 - 3 of Comparative Example 2 are exactly the same as those of Example 3. Step 4 is: The manganese iron hydrogen phosphate slurry is filtered and washed until the conductivity of the washing water < 600 us / cm, dried at 120 °C for 3 h to obtain manganese iron hydrogen phosphate material. Then, the manganese iron hydrogen phosphate material is used to replace the manganese iron phosphate material in Step 5, and 7.5 kg of vanadium pentoxide is not added in Step 5. The subsequent steps are the same as those of Example 3 to obtain sodium manganese iron phosphate product.

[0041] Send the sodium vanadium manganese iron phosphate material obtained in Example 3 for XRD ( Figure 1 ), and SEM ( Figure 2 ). From Figure 1It can be seen that the material prepared in the embodiment is a pure-phase sodium iron vanadium manganese phosphate material. From Figure 2 It can be seen that the sodium iron vanadium manganese phosphate material is in the shape of irregular flakes, and the primary particle size is 300-500 nm.

[0042] Take the sodium iron vanadium manganese phosphate prepared in Examples 1-3 and Comparative Example 1, and the sodium iron manganese phosphate product prepared in Comparative Example 2, test the tap density, then prepare a button cell under the same conditions, and then test its electrical properties under the same conditions according to the conventional method in the art. The electrical property test results of Examples 1-3 and Comparative Examples 1-2 are shown in Table 1 below: Table 1 Comparison of Electrical Properties

[0043] As can be seen from Table 1, the sodium iron vanadium manganese phosphate prepared in the examples has good tap and electrical properties. The tap density of Examples 1-3 is 0.3 g / cc higher than that of Comparative Examples 1-2. The 0.1C discharge capacity of the samples in Examples 1-3 reaches 145-150 mAh / g, which is 20-30 mAh / g higher than that of Comparative Examples 1-2. The prepared sodium iron vanadium manganese phosphate product has high tap density and high capacity, thus having a high energy density, and the process operation is simple, with the ability of industrial production.

[0044] The above embodiments are only for illustrating the technical solutions and features of the present invention, and their purpose is to better enable those familiar with the technology to implement it, and it should not be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention are within the protection scope of the present invention. Those not described in detail are prior arts.

Claims

1. A preparation method of sodium iron manganese vanadium phosphate as a sodium-ion battery cathode material, characterized in that, It includes the following steps: S1. Prepare a hydrogen phosphate solution and a manganous salt solution; S2. Use the hydrogen phosphate solution as a primer solution, and then add the manganous salt solution at room temperature. After the reaction, a manganese hydrogen phosphate crystal nucleus slurry is obtained; S3. Filter and wash the manganese hydrogen phosphate crystal nucleus slurry. After adding water to the washed manganese hydrogen phosphate material to make a slurry, when the temperature is raised to 85 - 95 °C, a ferrous source solution and a phosphate solution are added simultaneously. After the reaction, a ferromanganese hydrogen phosphate slurry is obtained; S4. The ferromanganese hydrogen phosphate slurry is filtered, washed, and dried. After drying, add water to make a slurry, add phosphoric acid, and when the temperature is raised to 90 - 100 °C, a ferromanganese phosphate compound precipitate is obtained through reaction. The ferromanganese phosphate compound precipitate is filtered, washed, and dried to obtain a ferromanganese phosphate material; S5. Stir and crush the ferromanganese phosphate material. After crushing, add a vanadium source, a sodium source, and a carbon source, and crush to the target particle size to obtain a dry powder; S6. Perform high-temperature sintering on the dry powder obtained in S5 to obtain the required sodium ferromanganese vanadium phosphate product.

2. The preparation method of a sodium-ion battery cathode sodium iron vanadium manganese phosphate material according to claim 1, characterized in that The hydrogen phosphate in the hydrogen phosphate solution in step S1 is at least one of sodium monohydrogen phosphate and sodium dihydrogen phosphate.

3. The preparation method of a sodium-ion battery cathode material of sodium iron vanadium manganese phosphate according to claim 1, wherein The manganous salt in the manganous salt solution in step S1 is at least one of manganese sulfate solution and manganese chloride.

4. The preparation method of a sodium-ion battery cathode material sodium iron vanadium manganese phosphate according to claim 1, characterized in that, In step S2, the reaction stirring speed is 50 - 200 rpm, the addition time of the manganous salt solution is 5 - 8 h, the reaction time after the manganous salt solution is added is 30 - 60 min, and the molar ratio of manganese to phosphorus in the manganous salt solution and the hydrogen phosphate solution is 1:

1.

5. The preparation method of a sodium-ion battery cathode material sodium iron vanadium manganese phosphate according to claim 1, characterized in that, In step S3, the ferrous source in the ferrous source solution is at least one of ferrous sulfate, ferrous chloride, and ferrous nitrate; the phosphate in the phosphate solution is at least one of ammonium monophosphate and ammonium dihydrogen phosphate. In S3, the molar ratio of iron, manganese, and phosphorus in the ferrous source solution, the manganous salt solution in S1, and the phosphate solution in S3 is 1:8:

1.

6. The preparation method of a sodium-ion battery cathode sodium iron vanadium manganese phosphate material according to claim 1, characterized in that, In step S3, when washing the slurry, the conductivity of the washing water < 1000 us / cm, the reaction stirring speed is 50 - 200 rpm, the addition time of the ferrous source solution and the phosphate solution is 5 - 8 h, and the reaction time after addition is 3 - 5 h.

7. The preparation method of a sodium-ion battery cathode material sodium iron vanadium manganese phosphate according to claim 6, characterized in that, In step S4, when washing the slurry, the conductivity of the washing water < 800 us / cm, the drying temperature is 120 °C, the drying time is 3 h, the phosphoric acid is phosphoric acid with a mass concentration of 40% - 85%, the reaction stirring speed is 50 - 200 rpm, the addition time of the phosphoric acid is 5 - 8 h, and the reaction time after adding the phosphoric acid is 3 - 5 h.

8. The preparation method of a sodium-ion battery cathode material of sodium iron vanadium manganese phosphate according to claim 1, wherein, The vanadium source in step S5 is at least one of vanadyl sulfate, vanadium pentoxide, and vanadium chloride; the sodium source is at least one of sodium carbonate, sodium phosphate, sodium monophosphate, and sodium dihydrogen phosphate; the carbon source is at least one of fructose, sucrose, and glucose.

9. The preparation method of a sodium-ion battery cathode sodium iron vanadium manganese phosphate material according to claim 1, characterized in that, In step S5, use a stirring crusher for stirring and crushing. The stirring speed is 500 - 1000 rpm, the speed of the crushing disk is 2000 - 5000 rpm, the crushing particle size of the ferromanganese phosphate is 100 - 300 nm, and the crushing particle size after adding the vanadium source, the sodium source, and the carbon source is 150 - 450 nm; the molar ratio of sodium to vanadium, the manganese source solution in S1, the ferrous source solution in S3, and the phosphorus source solution is 1:0.1:0.8:0.1:

1.

10. The preparation method of a sodium-ion battery cathode sodium iron vanadium manganese phosphate material according to claim 1, characterized in that, In step S6, the dry powder obtained in S5 is subjected to high-temperature sintering in a rotary kiln. The rotary frequency of the rotary kiln is 30 Hz, the temperature in the heating section is 150 - 600 °C, the temperature in the constant-temperature section is 800 - 1000 °C, the temperature in the cooling section is 200 - 300 °C, and the sintering time is 12 - 20 h.

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