Manganese oxide, method for preparing the same, and use thereof

Abstract

This invention relates to the field of lithium-ion battery manufacturing technology or magnetic components, specifically to a manganese oxide, its preparation method, and its applications. The method involves adding elemental manganese to water to prepare a manganese slurry, grinding the slurry to a particle size of Dv50: 3-5 μm, drying, and sintering to obtain the manganese oxide. This invention uses elemental manganese to prepare a manganese slurry, grinding the slurry to a specific particle size Dv50: 3-5 μm. On the one hand, grinding accelerates the hydrolysis rate of the substances in the manganese slurry; on the other hand, controlling the particle size achieves a more uniform formation of manganese oxide during sintering. The prepared manganese oxide has the characteristics of small cell parameters, dense crystal structure, low residual stress, strong Mn-O bond bonding, and low impurity content.

Description

Technical Field

[0001] This invention relates to the field of battery manufacturing technology or magnetic components, specifically to a manganese oxide, its preparation method, and its application. Background Technology

[0002] The battery industry and the magnetic materials synthesis industry are two important industrial sectors. Manganese tetroxide (MTE), as a key raw material, is widely used in the synthesis of battery cathode materials and magnetic materials. In battery manufacturing technology, MTE is a commonly used cathode material, and batteries made with MTE exhibit high energy density and long cycle life. In magnetic materials synthesis technology, MTE is an important precursor for magnetic materials, and it can be used to synthesize magnetic materials with excellent magnetic properties.

[0003] In the field of chemical engineering synthesis, the main methods for synthesizing manganese tetroxide include high-temperature solid-phase method, liquid-phase precipitation method, vapor-phase deposition method, and metallic manganese oxidation method. The high-temperature solid-phase method converts manganese oxide into manganese tetroxide through high-temperature heat treatment. The liquid-phase precipitation method involves adding a precipitant to precipitate manganese ions, followed by filtration, washing, and drying to obtain manganese tetroxide. The vapor-phase deposition method uses physical or chemical methods to react manganese oxide in the gas phase under specific temperature and pressure to generate manganese tetroxide. The metallic manganese oxidation method involves crushing metallic manganese flakes to a certain particle size, adding them to pure water to form a suspension, adding a catalyst to the suspension, catalytically oxidizing the manganese tetroxide in an atmosphere of air or oxygen, and then washing and drying to obtain manganese tetroxide.

[0004] The above-mentioned methods for preparing manganese tetroxide still have many drawbacks. For example, the high-temperature solid-phase method requires high temperatures, consumes a lot of energy, and the purity and consistency of the product are not easy to control (Mn element is easy to precipitate in the final product). The impurity content of manganese tetroxide obtained by the liquid-phase precipitation method is difficult to control, and it will generate a large amount of wastewater and waste residue, causing environmental pollution.

[0005] Therefore, existing synthesis methods cannot achieve precise control over the purity and consistency of manganese oxides, which to some extent limits their application in batteries and magnetic materials. Summary of the Invention

[0006] This invention provides a manganese oxide, its preparation method, and its applications. The preparation method of this invention yields a manganese oxide with high purity and good consistency. Using the manganese oxide of this invention to prepare cathode materials and batteries significantly improves battery performance, exhibiting high capacity and good cycle performance.

[0007] To achieve the above-mentioned technical objectives, the present invention provides a method for preparing manganese oxide, comprising adding elemental manganese to water to obtain manganese slurry, grinding the manganese slurry to a particle size Dv50 of 3-5 μm, drying, and sintering to obtain manganese tetroxide.

[0008] Furthermore, the solid content of the manganese slurry is 30-80%.

[0009] Furthermore, before grinding to a particle size Dv50 of 3-5 μm, the process further includes grinding the manganese slurry to a particle size Dv50 of 5-7 μm.

[0010] Furthermore, the drying temperature is 105-350℃ and the time is 1-4h; and / or, the sintering temperature is 900-1150℃ and the time is 2-24h.

[0011] Furthermore, the manganese paste also includes a doped cation source; after sintering, manganese oxide (Mn) is prepared. 1- x Me x )3O4, 0<x≤0.4; where Me is a cation in the doped cation source;

[0012] Preferably, the doped cation source is selected from at least one of Al source, Cr source, Co source, Fe source, Mg source, Ti source, V source, Ni source, Cu source, Zn source, Zr source, Nb source, Mo source, W source, Ca source, Y source, La source, Ce source, Ga source, and In source.

[0013] The present invention also provides a manganese oxide, which is prepared by the manganese oxide preparation method described above.

[0014] The present invention also provides a manganese oxide prepared by the above-described method or the application of the above-described manganese oxide in ferrite or cathode materials.

[0015] The present invention also provides a positive electrode material, wherein the raw material of the positive electrode material is the manganese oxide described above.

[0016] Preferably, the raw materials for the positive electrode material include the manganese oxide and lithium source described above; the molar ratio of lithium element in the lithium source to manganese element in the manganese oxide is (1.0-1.2):2;

[0017] Preferably, the raw materials for the cathode material include the manganese oxide, lithium source, phosphorus source and carbon source described above;

[0018] Preferably, the ratio of the number of moles of lithium in the lithium source, the total number of moles of metal elements in the manganese oxide, and the number of moles of phosphorus in the phosphorus source is (1.0-1.2):1:(1.03-1.05);

[0019] Wherein, the manganese oxide is (Mn 1-x Me x )3O4;

[0020] Preferably, the mass ratio of the total mass of the manganese oxide, lithium source, and phosphorus source to the mass of the carbon source is 100:(5-20);

[0021] Preferably, the carbon source is selected from one or more of sucrose, glucose, fructose, citric acid, phenolic resin, polyvinyl alcohol, polyethylene glycol, starch, carbon black, acetylene black, graphite, graphene, conductive carbon nanotubes, oxalic acid, urea, stearic acid, polyaniline, and cyclodextrin.

[0022] The present invention also provides a method for preparing the above-mentioned cathode material, the method comprising mixing raw materials for the cathode material and then sintering them;

[0023] Preferably, the sintering temperature is 400-1000℃ and the time is 6-24h.

[0024] The technical solution of the present invention has the following beneficial effects:

[0025] 1. This invention provides a method for preparing manganese oxide, comprising: adding elemental manganese to water to obtain a manganese slurry; grinding the manganese slurry to a particle size Dv50 of 3-5 μm; drying; and sintering to obtain manganese oxide. This invention uses elemental manganese to prepare a manganese slurry, and grinds the slurry to a specific particle size Dv50 of 3-5 μm. On the one hand, grinding accelerates the hydrolysis rate of the substances in the manganese slurry; on the other hand, controlling the particle size achieves the formation of manganese oxide with better uniformity during sintering. The prepared manganese oxide has the characteristics of small cell parameters, dense crystal structure, low residual stress, strong Mn-O bond bonding, and low impurity content.

[0026] 2. The present invention provides a positive electrode material, wherein the raw material of the positive electrode material includes manganese oxide prepared in this application, and the positive electrode material prepared using the raw material has the characteristic of high compaction density; the positive electrode material is further prepared into a battery; the performance of the prepared battery is significantly improved, exhibiting the characteristics of high capacity, good cycle performance and low metal dissolution. Attached Figure Description

[0027] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 The image shows a SEM image of manganese tetroxide prepared in Example 1 of Experiment 1.

[0029] Figure 2 The image shows the XRD pattern of manganese tetroxide prepared in Example 1 of Experiment 2.

[0030] Figure 3 The image shows the high-temperature cycling at 45°C of the coin cell prepared from the lithium manganese oxide cathode material obtained in Example 4. Detailed Implementation

[0031] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0032] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0033] In the examples and comparative examples, the particle size of the slurry was tested according to the testing standard specified in GB / T19077.1-2016.

[0034] The metallic manganese powder used in the examples and comparative examples was purchased from Sinosteel Tianyuan and conforms to standard YB / T051-2015D.

[0035] Example 1

[0036] This embodiment provides manganese tetroxide and its preparation method, which includes the following steps:

[0037] S1. Add metallic manganese powder to deionized water to prepare a manganese slurry with a solid content of 70%.

[0038] S2. The manganese slurry obtained in step S1 is placed in a ball mill and subjected to two ball milling processes. First, it is ball milled at a speed of 1200 rpm for 30 minutes to obtain the manganese slurry after the first ball milling. The particle size of the solid slurry in the manganese slurry is tested, and the particle size Dv50 is measured to be 6±1μm. Then, it is ball milled at a speed of 1500 rpm for 20 minutes to obtain the manganese slurry after the second ball milling. The particle size of the slurry in the manganese slurry is tested, and the particle size Dv50 is measured to be 4±1μm.

[0039] S3. Place the manganese slurry after the second ball milling in step S2 into a drying oven and dry it at 205℃ for 2 hours to obtain powder.

[0040] S4. Place the powder obtained in step S3 into a high-temperature furnace and sinter it at 1000°C in air for 10 hours to obtain manganese tetroxide.

[0041] Example 2

[0042] This embodiment provides a method for preparing manganese tetroxide, with step S2 differing from that in Example 1, while the remaining steps are the same. S2: The manganese slurry obtained in step S1 is placed in a ball mill and ball-milled for 120 minutes at a speed of 1500 rpm to obtain the ball-milled manganese slurry. The particle size Dv50 of the manganese slurry is measured to be 4 ± 1 μm.

[0043] Example 3

[0044] This embodiment provides a method for preparing manganese tetroxide, with step S1 differing from that in Example 1, while the remaining steps are the same. S1: Add metallic manganese powder to deionized water to prepare a manganese slurry with a solid content of 60%.

[0045] S2. The manganese slurry obtained in step S1 is placed in a ball mill and subjected to two ball milling processes. First, it is ball milled at a speed of 1200 rpm for 30 min to obtain the manganese slurry after the first ball milling. The particle size of the solid slurry in the manganese slurry is measured, and the particle size Dv50 is found to be 6±1 μm. Then, it is ball milled at a speed of 1500 rpm for 20 min to obtain the manganese slurry after the second ball milling. The particle size of the slurry in the manganese slurry is measured, and the particle size Dv50 is found to be 4±1 μm.

[0046] S3. Place the manganese slurry after the second ball milling in step S2 into a drying oven and dry it at 205℃ for 2 hours to obtain powder.

[0047] S4. Place the powder obtained in step S3 into a high-temperature furnace and sinter it at 1000°C in air for 10 hours to obtain manganese tetroxide.

[0048] Example 4

[0049] This embodiment provides a cathode material, lithium manganese oxide, whose raw materials include manganese tetroxide prepared in Example 1 and lithium hydroxide; the molar ratio of lithium element in lithium hydroxide to manganese element in manganese tetroxide is 1.06:2.

[0050] The preparation method includes weighing manganese tetroxide obtained in Example 1 and mixing it thoroughly with lithium hydroxide, and sintering the mixed material at 800°C for 8 hours to obtain lithium manganese oxide as the cathode material.

[0051] Example 5

[0052] This embodiment provides a manganese oxide, lithium manganese oxide and its preparation method. The preparation method includes the following steps: steps S1-S3 are the same as steps S1-S3 in Example 1;

[0053] S4. Weigh aluminum oxide and mix it with the powder obtained in step S3 according to the molar ratio of aluminum to manganese of 0.005:0.995. Place the mixture in a high-temperature furnace and sinter at 1100°C for 15 hours in air atmosphere to prepare aluminum manganese oxide (Mn). 0.995 Al 0.005 )3O4.

[0054] S5. Weigh lithium hydroxide and the aluminum manganese oxide prepared in step S4 according to a molar ratio of lithium element and metal element in aluminum manganese oxide of 1.08:2, and mix them thoroughly. Sinter the mixture at 800℃ for 8 hours to prepare aluminum-doped lithium manganese oxide (LiMn). 1.99 Al 0.01 O4.

[0055] Example 6

[0056] This embodiment provides a method for preparing manganese tetroxide, lithium manganese iron phosphate, and their preparation. Steps S4 and S5 differ from those in Example 5, while the remaining steps are the same. S4: Ferric oxide and magnesium oxide are weighed and mixed with the powder obtained in step S3 according to a molar ratio of iron, magnesium, and manganese of 0.396:0.004:0.6. The mixed material is placed in a high-temperature furnace and sintered at 1100°C for 15 hours in air atmosphere to obtain manganese iron magnesium oxide (Mn). 0.6 Fe 0.396 Mg 0.004 )3O4.

[0057] S5. Lithium hydroxide, the manganese-iron-magnesium oxide prepared in step S4, and ammonium hydrogen phosphate were weighed and thoroughly mixed according to a molar ratio of lithium, metal, and phosphorus of 1.05:1:1.03 to obtain a mixture. Glucose (20% of the mass of the mixture) was weighed and thoroughly mixed with the mixture, and then sintered at 700℃ for 6 hours to prepare magnesium-doped manganese-iron-phosphate lithium (LiMn). 0.6 Fe 0.396 Mg 0.004 PO4 / C.

[0058] Example 7

[0059] This embodiment provides a method for preparing manganese tetroxide, spinel-type lithium nickel manganese oxide, and their preparation. Steps S4 and S5 differ from those in Example 5, while the remaining steps are the same. S4: Nickel oxide is weighed and mixed with the powder obtained in step S3 according to a nickel to manganese molar ratio of 0.25:0.75. The mixed material is placed in a high-temperature furnace and sintered at 1100°C for 15 hours in air atmosphere to obtain nickel manganese oxide (Mn). 0.75 Ni 0.25 )3O4.

[0060] S5. Weigh lithium carbonate and the nickel-manganese oxide prepared in step S4 according to a molar ratio of lithium to metal elements of 1.03:2, and mix them thoroughly. Sinter the mixture at 800℃ for 10 hours to prepare spinel-type lithium nickel-manganese oxide (LiNi). 0.5 Mn 1.5 O4.

[0061] Example 8

[0062] This embodiment provides a method for preparing manganese tetroxide, lithium aluminum manganese oxide, and their preparation. Steps S4 and S5 differ from those in Example 5, while the remaining steps are the same. S4: Aluminum tetroxide is weighed and mixed with the powder obtained in step S3 according to a molar ratio of aluminum to manganese of 0.05:0.95. The mixed material is placed in a high-temperature furnace and sintered at 1100°C for 15 hours in air atmosphere to obtain aluminum manganese oxide (Mn). 0.95 Al 0.05 )3O4.

[0063] S5. Weigh lithium hydroxide and the aluminum manganese oxide prepared in step S4 according to a molar ratio of lithium to metal elements of 1.02:2, and mix them thoroughly. Sinter the mixture at 700℃ for 6 hours to prepare lithium aluminum manganese oxide (LiAl). 0.1 Mn 1.9 O4.

[0064] Comparative Example 1

[0065] This comparative example provides a manganese oxide, lithium manganese oxide, and their preparation method, which is basically the same as Example 5, except that the second ball milling time in step S2 is different. In this comparative example, the time is 70 min, and a manganese slurry after the second ball milling is obtained. The particle size of the solid in the manganese slurry is measured, and the particle size Dv50 is measured to be 1.5±1μm.

[0066] Comparative Example 2

[0067] This comparative example provides a method for preparing manganese tetroxide, lithium manganese oxide, and the same as in Example 5. The difference is that in step S2, the manganese slurry obtained in step S1 is placed in a ball mill and subjected to two ball milling processes. First, the manganese slurry is ball-milled at 1200 rpm for 20 min to obtain the first ball-milled manganese slurry. The particle size of the solid in the manganese slurry is measured, and the measured particle size Dv50 is 8±1 μm. Then, the manganese slurry is ball-milled at 1500 rpm for 15 min to obtain the second ball-milled manganese slurry. The particle size of the solid in the manganese slurry is measured, and the measured particle size Dv50 is 6.5±1 μm.

[0068] Experimental Example 1

[0069] The manganese tetroxide prepared in Example 1 was analyzed by SEM. The results are shown in [Figure 1]. Figure 1 As shown, the manganese tetroxide particles prepared in Example 1 have a uniform size distribution and good morphological consistency.

[0070] Experimental Example 2

[0071] The manganese tetroxide obtained in Examples 1-3 and Comparative Example 1, and the manganese tetroxide doped with cation source obtained in step S4 of Examples 5-8 and Comparative Example 2 were subjected to purity testing, consistency evaluation, and performance testing.

[0072] Purity testing method: The crystal structure of the sample was determined using a Rigaku D / MAX-2500VL / PC X-ray diffractometer (Japan). The target was Cu with Kα rays, wavelength λ = 0.15406 nm, 2θ angle scanning range of 5° to 90°, and scanning rate of 5° / min. Figure 2 The image shows an X-ray image of manganese tetroxide prepared in Example 1.

[0073] The method for determining manganese (Mn) content is as follows: Ferrous ammonium sulfate titration is used. First, a certain amount of sample is weighed and dissolved and oxidized with phosphoric acid and nitric acid. Then, the manganese ions in the solution are completely converted into manganese phosphate complexes by heating. Next, titration is performed using a standard ferrous ammonium sulfate solution. The titration endpoint is observed by adding an indicator. Finally, the manganese content in the sample is calculated based on the amount consumed in the titration.

[0074] The test results are shown in Table 1.

[0075] Table 1 Test Results

[0076]

[0077] Experimental Example 3

[0078] The cathode materials prepared in Examples 4-8 and Comparative Examples 1-2 were subjected to performance testing, including discharge specific capacity and high-temperature cycling.

[0079] The performance of batteries made from the positive electrode materials prepared in each embodiment and comparative example was tested. The battery preparation method is as follows: The positive electrode material, carbon nanotubes, and polyvinylidene fluoride binder were mixed in a solvent (NMP) at a fixed mass ratio of 80:15:5. After stirring evenly, the mixture was uniformly coated onto a current collector aluminum foil, pressed into a film, dried, and then cut into circular pieces with a diameter of 12 mm to obtain the positive electrode sheet of the coin cell. A lithium sheet (thickness of 0.6 mm) was used as the negative electrode, and a solution of vinyl fluoride carbonate, dimethyl carbonate, and ethylene carbonate (volume ratio of 10:45:45) containing 1 mol / L LiPF6 was used as the electrolyte. A 20 μm polypropylene dry-process separator was used as the separator, and the coin cell was assembled in an argon atmosphere in a glove box.

[0080] Methods for detecting discharge capacity:

[0081] At 25°C, the batteries corresponding to Examples 4, 5, 6, and 8 were charged at a constant current of 0.1C to 4.3V at a voltage of 3.0-4.3V, left to stand for 15 minutes, discharged at a constant current of 0.1C to 3.0V, and the discharge capacity was recorded. Then, they were charged at 1C to 4.3V, then charged at a constant voltage to 0.05C, left to stand for 15 minutes, and then discharged at 1C to 3.0V, and the discharge capacity was recorded.

[0082] At 25°C, the battery corresponding to the nickel-manganese binary material obtained in Example 7 was charged at a constant current of 0.1C to 4.8V under a voltage of 3.5-4.8V, left to stand for 15 minutes, discharged at a constant current of 0.1C to 3.5V, and the discharge capacity was recorded. Then it was charged at 1C to 4.8V, then charged at a constant voltage to 0.05C, left to stand for 15 minutes, and then discharged at 1C to 3.5V, and the discharge capacity was recorded.

[0083] The detection method for all-electric high-temperature cycling is charge-discharge cycling: charge at 1C to the upper voltage limit of each material, then charge at a constant voltage to 0.05C, rest for 15 minutes, and then discharge at 1C to the lower voltage limit. Repeat this cycle until the capacity decays to 80% of the initial capacity and record the number of cycles. The entire cycling process is carried out at 45°C. Figure 3 This is a graph showing the relationship between the capacity retention rate and the number of cycles for the battery corresponding to Example 4.

[0084] Manganese leaching detection method: Take 5.000g of the test sample (the positive electrode material, carbon nanotubes and binder polyvinylidene fluoride are mixed in a solvent (NMP) at a fixed mass ratio of 80:15:5, and dried to obtain the test sample) and pour it into 100ml of ultrapure water. Seal the sample and place it in a constant temperature water bath at 25℃ for 70h. After standing, filter the sample with quantitative filter paper and keep the filtered liquid. Use a 1ml pipette to take 1ml of the filtrate into a 50ml volumetric flask, add 2ml of nitric acid and shake well. Then, test the manganese content on the ICO-OES equipment.

[0085] The test results are shown in Table 2.

[0086] Table 2 Detection Results

[0087]

[0088]

[0089] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing manganese oxide, characterized in that, The process involves mixing elemental manganese with water to prepare a manganese slurry, grinding the slurry to a particle size Dv50 of 3-5 μm, drying, and sintering to obtain manganese oxides.

2. The method for preparing manganese oxide according to claim 1, characterized in that, The solid content of the manganese paste is 30-80%.

3. The method for preparing manganese oxide according to claim 1, characterized in that, Before grinding the manganese slurry to a particle size Dv50 of 3-5 μm, the process also includes grinding the manganese slurry to a particle size Dv50 of 5-7 μm.

4. The method for preparing manganese oxide according to any one of claims 1-3, characterized in that, The drying temperature is 105-350℃, and the time is 1-4 hours; and / or, The sintering temperature is 900-1150℃, and the time is 2-24h.

5. The method for preparing manganese oxide according to any one of claims 1-4, characterized in that, The manganese paste also includes a doped cation source; After sintering, manganese oxide (Mn) was prepared. 1-x Me x )3O4, 0<x≤0.4, where Me is a cation in the doped cation source; Preferably, the doped cation source is selected from one or more of Al source, Cr source, Co source, Fe source, Mg source, Ti source, V source, Ni source, Cu source, Zn source, Zr source, Nb source, Mo source, W source, Ca source, Y source, La source, Ce source, Ga source, and In source.

6. A manganese oxide, characterized in that, It is prepared by the method for preparing manganese oxide according to any one of claims 1-5.

7. The application of a manganese oxide prepared by any of the methods for preparing manganese oxide according to claims 1-5, or the manganese oxide according to claim 6, in ferrite or cathode materials.

8. A positive electrode material, characterized in that, The raw material for the cathode material includes the manganese oxide described in claim 6.

9. The cathode material according to claim 8, characterized in that, The raw materials for the cathode material include the manganese oxide and lithium source as described in claim 6; the molar ratio of lithium element in the lithium source to manganese element in the manganese oxide is (1.0-1.2):(1-2); Preferably, the raw materials for the cathode material include the manganese oxide, lithium source, phosphorus source and carbon source as described in claim 6; Preferably, the ratio of the number of moles of lithium in the lithium source, the total number of moles of metal elements in the manganese oxide, and the number of moles of phosphorus in the phosphorus source is (1.0-1.2):1:(1.03-1.05); Wherein, the manganese oxide is (Mn 1-x Me x )3O4; Preferably, the mass ratio of the total mass of the manganese oxide, lithium source, and phosphorus source to the carbon source as described in claim 6 is 100:(5-20); Preferably, the carbon source is selected from one or more of sucrose, glucose, fructose, citric acid, phenolic resin, polyvinyl alcohol, polyethylene glycol, starch, carbon black, acetylene black, graphite, graphene, conductive carbon nanotubes, oxalic acid, urea, stearic acid, polyaniline, and cyclodextrin.

10. A method for preparing the cathode material according to claim 8 or 9, characterized in that, The preparation method includes mixing raw materials for the cathode material and then sintering them. Preferably, the sintering temperature is 400-1000℃ and the time is 6-24h.

Images