β-MnOOH, its synthesis methods, and applications

Abstract

This invention provides a β-MnOOH, wherein the β-MnOOH is a three-dimensional network of spherical or near-spherical secondary particles formed by winding ribbon-like primary particles, and the secondary particles are loose and porous; the specific surface area of ​​the β-MnOOH is 50 m². 2 The β-MnOOH exhibits a high specific surface area and high activity, making it an excellent precursor and catalyst for manganese oxides. A method for preparing the β-MnOOH is also provided, which involves a one-step liquid-phase precipitation method. This method boasts high synthesis efficiency, low synthesis temperature, and controllable manganese oxidation degree through process control, yielding β-MnOOH with a stable valence state and excellent morphology. This preparation method offers high process stability, simplicity, minimal equipment requirements, no need for complexing agents, low cost, scalability, and ease of industrialization.

Description

Technical Field

[0001] This invention belongs to the field of manganese compound technology, specifically relating to a method for synthesizing β-MnOOH and its application. Background Technology

[0002] Manganese hydroxyl oxide (MnOOH) is a very important compound of manganese. Due to its unique physicochemical properties, MnOOH has significant applications in catalysts, sensors, adsorbents, supercapacitors, lithium-ion and sodium-ion batteries. Furthermore, MnOOH is considered the simplest and most practical precursor for preparing manganese oxides. Based on the different internal atomic connections, MnOOH exists in three crystal forms: α-MnOOH (orthorhombic), β-MnOOH (hexagonal), and γ-MnOOH (manganese hydrate). Both α-MnOOH and γ-MnOOH possess a tunnel-like structure, while β-MnOOH has a layered structure with an interlayer spacing of 0.46 nm. Because its layers are uncharged and there are no cations or anions between the layers, β-MnOOH is an electrically neutral layered compound. β-MnOOH is metastable, while γ-MnOOH is the most stable and can transform into γ-MnOOH under certain conditions.

[0003] Loose, nanoscale β-MnOOH is an excellent cathode precursor material, serving as a precursor for materials such as lithium manganese oxide or manganese phosphate. The high specific surface area and low sulfur content of nanoscale β-MnOOH are beneficial for improving the crystallinity of cathode materials and enhancing electrochemical performance. Furthermore, the high specific surface area of ​​β-MnOOH nanowires, containing free hydroxyl groups, also makes them an excellent support for the preparation of nanocomposite materials, exhibiting superior catalytic performance.

[0004] Currently, the synthesis of β-hydroxy manganese oxide is mostly carried out by hydrothermal method, which has high synthesis temperature and high cost, making it unfavorable for industrial production. In addition, the manganese source is mostly potassium permanganate, and the reducing agent is mostly organic molecule, which is environmentally unfriendly, has poor safety, and is easy to introduce impurities.

[0005] Patent document CN102531064A discloses a method for preparing ultrafine single-crystal manganese oxide nanowires. This method uses potassium permanganate as a raw material and organic molecules such as polyvinylpyrrolidone (K30, KSO, etc.) and sodium dodecyl sulfate as reducing agents. The hydrothermal reaction is carried out in a closed reactor at a temperature of 120-170°C, which can produce large quantities of ultrafine single-crystal manganese oxide (MnOOH) nanowires with diameters of around 100 nm and different aspect ratios. However, this method involves high reaction temperatures, expensive raw materials, and poor reaction safety, making it unsuitable for industrial production.

[0006] Patent document CN1831210A discloses a method for preparing multi-branched manganese oxide single-crystal nanoflowers. This method uses potassium permanganate as an oxidant and polyethylene glycol as a reducing agent, and carries out a hydrothermal reaction in a closed reactor at a temperature of 100~200℃. By controlling the reaction temperature, reaction time and raw material ratio, multi-branched manganese oxide single-crystal nanoflowers can be prepared. The diameter of each branch is 40~100nm and the length is 800~1000nm. However, this method also uses a hydrothermal method, which has problems such as excessively high reaction temperature, expensive raw material cost and poor safety. Summary of the Invention

[0007] To address the aforementioned technical problems, this application provides a β-MnOOH, its preparation method, and its application.

[0008] To achieve the above objectives, this application proposes the following technical solution:

[0009] In a first aspect, a β-MnOOH is provided, wherein the β-MnOOH is a three-dimensional network of spherical or near-spherical secondary particles formed by the winding of ribbon-like primary particles, the secondary particles being loose and porous, and the specific surface area of ​​the β-MnOOH being 50 m². 2 / g or more.

[0010] Preferably, the specific surface area of ​​the β-MnOOH is 50~100m². 2 / g; the Mn content of the β-MnOOH is 60~65wt%; the sulfur content of the β-MnOOH is less than 1000ppm; the diameter of the ribbon-like primary particles is 10~50nm; the particle size of the secondary particles is 2~20μm.

[0011] Secondly, a method for synthesizing β-MnOOH is provided, comprising:

[0012] A divalent manganese source solution, an oxidant solution, and a pH adjuster solution are introduced concurrently into the bottom liquid of the reaction vessel and stirred. The flow rate of the manganese source solution is 100~600 mL / min. During the reaction, the pH of the system is maintained at 9.5~10.5. After the reaction is completed, the mixture is filtered, washed, and dried to obtain β-MnOOH.

[0013] Preferably, the pH of the bottom liquid in the reactor is 9.5 to 10.5; preferably, the bottom liquid in the reactor is prepared using water and a pH adjuster; preferably, the amount of the bottom liquid in the reactor is 20 to 40% of the volume of the reactor used to synthesize β-MnOOH.

[0014] Preferably, the divalent manganese source is one or more of manganese sulfate, manganese nitrate, manganese chloride, manganese oxalate, and manganese acetate; preferably, the molar concentration of the manganese source in the manganese source solution is 0.2~2.0 mol / L.

[0015] Preferably, the temperature of the stirring reaction is controlled at 30~80℃; the stirring reaction time is 1~8h.

[0016] Preferably, the reaction is carried out in an air atmosphere.

[0017] Preferably, the oxidant is one or more of the following: hydrogen peroxide, ammonium persulfate, sodium persulfate, potassium persulfate, ozone, nitric acid, ammonium nitrate, potassium nitrate, sodium nitrate, potassium permanganate, dichromic acid, chlorine, chloric acid, hypochlorous acid, chlorite, perchloric acid, hypoiodic acid, metaperiodic acid, bromic acid, hypobromic acid, perbromic acid, and ferrate.

[0018] Preferably, the concentration of the oxidant solution is 1~10 mol / L.

[0019] Preferably, the pH adjuster is ammonia and / or sodium hydroxide; more preferably, the concentration of the pH adjuster solution is 0.5~5 mol / L.

[0020] Preferably, the flow rate of the oxidant solution and the flow rate of the manganese source solution are determined according to the molar ratio of oxidant to manganese source per unit time of 1 to 4:1.

[0021] Preferably, the flow rate of the manganese source solution is 200~500 mL / min.

[0022] Thirdly, the aforementioned β-MnOOH or β-MnOOH prepared by the aforementioned preparation method is also provided as a precursor or catalyst for positive electrode materials.

[0023] Compared with the prior art, one or more of the above technical solutions can achieve at least one of the following beneficial effects:

[0024] The provided β-MnOOH consists of three-dimensional network spherical or near-spherical secondary particles formed by the winding of ribbon-like primary particles. It has a high specific surface area and high activity, making it an excellent precursor and catalyst for manganese oxides.

[0025] β-MnOOH can be synthesized via a one-step liquid-phase precipitation method. This method boasts high synthesis efficiency, low synthesis temperature, and controllable manganese oxidation through process control, yielding stable trivalent β-MnOOH. The process is stable, simple, requires no complexing agents, has low equipment requirements, low cost, and is suitable for large-scale production, facilitating industrialization. The synthesized β-MnOOH exhibits high purity, high BET content, low S content, low impurity content, and high powder activity, making it an excellent precursor and catalyst for manganese oxides. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the 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 based on these drawings without creative effort.

[0027] Figure 1 The images show the XRD patterns of MnOOH prepared in Examples 1-8.

[0028] Figure 2 The XRD patterns are of the MnOOH prepared in Comparative Examples 1-5.

[0029] Figure 3 SEM images of MnOOH prepared in Example 1 at different magnifications.

[0030] Figure 4 SEM images of MnOOH prepared in Example 2 at different magnifications.

[0031] Figure 5 SEM images of MnOOH prepared in Example 3 at different magnifications.

[0032] Figure 6 SEM images of MnOOH prepared in Example 4 at different magnifications.

[0033] Figure 7 SEM images of MnOOH prepared in Example 5 at different magnifications.

[0034] Figure 8 SEM images of MnOOH prepared in Example 6 at different magnifications.

[0035] Figure 9 SEM images of MnOOH prepared in Example 7 at different magnifications.

[0036] Figure 10 SEM images of MnOOH prepared in Example 8 at different magnifications.

[0037] Figure 11 SEM images of MnOOH prepared in Comparative Example 1 at different magnifications.

[0038] Figure 12 SEM images of MnOOH prepared in Comparative Example 2 at different magnifications.

[0039] Figure 13 SEM images of MnOOH prepared in Comparative Example 3 at different magnifications.

[0040] Figure 14 SEM images of MnOOH prepared in Comparative Example 4 at different magnifications.

[0041] Figure 15 SEM images of MnOOH prepared in Comparative Example 5 at different magnifications. Detailed Implementation

[0042] This invention provides a β-MnOOH, wherein the β-MnOOH is a three-dimensional network of spherical or near-spherical secondary particles formed by winding ribbon-like primary particles, and the secondary particles are loose and porous; the specific surface area of ​​the β-MnOOH is 50 m². 2 / g or more. First, the pure phase β-MnOOH is metastable, with a large free energy and high surface activity, which is beneficial for Li intercalation and improves electrochemical activity as a cathode material precursor. Second, this morphology of β-MnOOH has the characteristics of high specific surface area and high activity, which is beneficial for Li intercalation and improves electrochemical activity as a cathode material precursor. Moreover, the ribbon-like primary particles are not conducive to the entrainment of impurity sulfur, so the impurity sulfur content is low.

[0043] In some preferred embodiments, the specific surface area of ​​the β-MnOOH is 50~100 m². 2 / g, for example 50m 2 / g、55m 2 / g、60m 2 / g、65m 2 / g、70m 2 / g、75m 2 / g、80m 2 / g、85m 2 / g、90m 2 / g、95m 2 / g, 100m 2 / g etc.

[0044] In some preferred embodiments, the Mn content of the β-MnOOH is 60~65 wt.%, for example 60 wt.%, 61 wt.%, 62 wt.%, 63 wt.%, 64 wt.%, 65 wt.%, etc.

[0045] In some preferred embodiments, the sulfur content of the β-MnOOH is below 1000 ppm, more preferably below 800 ppm, and even more preferably below 700 ppm. On the one hand, a lower impurity content is beneficial to improving material performance; on the other hand, a lower impurity sulfur content results in smaller primary particles on the surface, and the material formed by smaller primary particles has higher activity and specific surface area.

[0046] In some preferred embodiments, the diameter of the ribbon-like primary particles is 10~50nm, such as 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, 50nm, etc.; the particle size of the secondary particles is 2~20μm, such as 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, etc.

[0047] Some embodiments of this application provide a method for synthesizing β-MnOOH, including:

[0048] A divalent manganese source solution, an oxidant solution, and a pH adjuster solution are introduced concurrently into the bottom liquid of the reaction vessel, and the mixture is stirred during the reaction. The flow rate of the manganese source solution is 100~600 mL / min. During the reaction, the pH of the system is maintained at 9.5~10.5 (e.g., 9.5, 9.8, 10, 10.2, 10.5, etc.). After the reaction is completed, the mixture is filtered, washed, and dried to obtain β-MnOOH.

[0049] In some preferred embodiments, the pH of the bottom liquid of the reaction vessel is 9.5~10.5, such as 9.5, 9.8, 10, 10.2, 10.5, etc.; the bottom liquid of the reaction vessel is prepared with water and pH adjuster; the amount of the bottom liquid of the reaction vessel is 20~40% of the volume of the synthesis vessel for synthesizing β-MnOOH, such as 20%, 25%, 30%, 35%, 40%, etc.

[0050] In some preferred embodiments, the reaction is carried out in an air atmosphere.

[0051] In some preferred embodiments, the divalent manganese source is one or more of manganese sulfate, manganese nitrate, manganese chloride, manganese oxalate, and manganese acetate.

[0052] In some preferred embodiments, the molar concentration of the manganese source in the manganese source solution is 0.2~2.0 mol / L.

[0053] In some preferred embodiments, the oxidant is one or more of hydrogen peroxide, ammonium persulfate, sodium persulfate, potassium persulfate, ozone, nitric acid, ammonium nitrate, potassium nitrate, sodium nitrate, potassium permanganate, dichromic acid, chlorine, chloric acid, hypochlorous acid, chlorite, perchloric acid, hypoiodic acid, metaperiodic acid, bromic acid, hypobromic acid, perbromic acid, and ferrate.

[0054] In some preferred embodiments, the concentration of the oxidant solution is 1~10 mol / L, for example, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L, 10 mol / L, etc.

[0055] In some preferred embodiments, the pH adjuster is sodium hydroxide; the concentration of the pH adjuster solution is 1~15 mol / L, for example, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L, 10 mol / L, 11 mol / L, 12 mol / L, 13 mol / L, 14 mol / L, 15 mol / L, etc.

[0056] In some preferred embodiments, the temperature of the stirring reaction is controlled at 30~80℃, for example, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, etc.; the stirring reaction time is 1~8h, for example, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, etc.

[0057] In some preferred embodiments, the molar amount of oxidant introduced per unit time is 2 to 8 times the amount theoretically required to achieve oxidation of manganese source introduced per unit time, such as 2 times, 3 times, 4 times, 5 times, 6 times, 7 times, 8 times, etc.

[0058] In some preferred embodiments, the flow rate of the manganese source solution is 200~500 mL / min, such as 200 mL / min, 250 mL / min, 300 mL / min, 350 mL / min, 400 mL / min, 450 mL / min, 500 mL / min, etc.

[0059] In some embodiments, the manganese source solution is obtained by dissolving the manganese source in deionized water.

[0060] In some embodiments, the pH adjusting agent solution is obtained by dissolving the pH adjusting agent in water and filtering.

[0061] In some embodiments, the oxidant solution is obtained by dissolving the oxidant in water and filtering.

[0062] In some preferred embodiments, the drying is oven drying; the oven drying temperature is 80~150℃.

[0063] In all embodiments, the water is deionized water.

[0064] Some embodiments of this application also provide a β-MnOOH, synthesized using the aforementioned synthesis method.

[0065] The present invention also provides the application of the aforementioned β-MnOOH or β-MnOOH prepared by the aforementioned preparation method as a precursor or catalyst for positive electrode materials.

[0066] To facilitate understanding of the present invention, the invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0067] Particle size distribution test: Malvern 3000 particle size analyzer.

[0068] BET test: Surface area analyzer, model BSD-BET400, manufactured by Best Instrument Technology (Beijing) Co., Ltd.

[0069] Tap test: Tap density meter, model BT-313, manufactured by Dandong Better Instruments Co., Ltd.

[0070] Method for testing the content of Mn, Fe, P, and S elements: ICP.

[0071] Example 1

[0072] Step S1, preparation of manganese source solution:

[0073] Manganese sulfate was dissolved in deionized water to prepare a 50L manganese sulfate solution with a concentration of 1.5mol / L. The solution was then filtered to obtain solution A.

[0074] Step S2, Preparation of oxidant:

[0075] Prepare a hydrogen peroxide solution B with a volume of 5.62 L and a concentration of 8.9 mol / L.

[0076] Step S3, pH adjuster preparation:

[0077] Prepare a 10.8 mol / L sodium hydroxide solution C;

[0078] Step S4, synthesis reaction;

[0079] Add one-third volume of deionized water to the reactor, heat to 40°C, stir at 300 rpm, and introduce a small amount of NaOH until the pH reaches 9.6-9.9. Then, pump solutions A and B into the synthesis reactor. The molar flow rate ratio of solution A to solution B is 2:1, and the flow rate of solution A is 200 mL / min. At the same time, pump solution C to maintain the pH at 9.6-9.9.

[0080] Step S5: Dehydration, washing, and drying

[0081] After the reaction was completed, the wet material was obtained by washing, centrifugation and drying, and then dried in an oven at 120℃ to obtain manganese hydroxyoxide.

[0082] Example 2

[0083] Step S1, preparation of manganese source solution:

[0084] Manganese sulfate was dissolved in deionized water to prepare a 50L manganese sulfate solution with a concentration of 1.5mol / L. The solution was then filtered to obtain solution A.

[0085] Step S2, Preparation of oxidant:

[0086] Prepare a hydrogen peroxide solution B with a volume of 10.11 L and a concentration of 8.9 mol / L.

[0087] Step S3, pH adjuster preparation:

[0088] Prepare a 10.8 mol / L sodium hydroxide solution C;

[0089] Step S4, synthesis reaction;

[0090] Add one-third of the volume of deionized water to the reactor, heat to 40°C, stir at 300 rpm, and introduce a small amount of NaOH to bring the pH to 10-10.4. Then, pump solutions A and B into the synthesis vessel. The molar flow rate ratio of solution A to solution B is 1.2:1, and the flow rate of solution A is 200 mL / min. At the same time, pump solution C to maintain the pH at 10-10.4.

[0091] Example 3

[0092] Step S1, preparation of manganese source solution:

[0093] Manganese sulfate was dissolved in deionized water to prepare a 50L manganese sulfate solution with a concentration of 1.5mol / L. The solution was then filtered to obtain solution A.

[0094] Step S2, Preparation of oxidant:

[0095] Prepare a hydrogen peroxide solution B with a volume of 10.11 L and a concentration of 8.9 mol / L.

[0096] Step S3, pH adjuster preparation:

[0097] Prepare a 10.8 mol / L sodium hydroxide solution C;

[0098] Step S4, synthesis reaction;

[0099] Add one-third of the volume of deionized water to the reactor, heat to 40°C, stir at 500 rpm, and introduce a small amount of NaOH to bring the pH to 10-10.4. Then, pump solutions A and B into the synthesis vessel. The molar flow rate ratio of solution A to solution B is 1.2:1, and the flow rate of solution A is 200 mL / min. At the same time, pump solution C to maintain the pH at 10-10.4.

[0100] Example 4

[0101] Step S1, preparation of manganese source solution:

[0102] Manganese sulfate was dissolved in deionized water to prepare a 50L manganese sulfate solution with a concentration of 1.5mol / L. The solution was then filtered to obtain solution A.

[0103] Step S2, Preparation of oxidant:

[0104] Prepare a hydrogen peroxide solution B with a volume of 5.62 L and a concentration of 8.9 mol / L.

[0105] Step S3, pH adjuster preparation:

[0106] Prepare a 10.8 mol / L sodium hydroxide solution C;

[0107] Step S4, synthesis reaction;

[0108] Add one-third of the volume of deionized water to the reactor, heat to 40°C, stir at 300 rpm, and introduce a small amount of NaOH to bring the pH to 10-10.4. Then, pump solutions A and B into the synthesis vessel. The molar flow rate ratio of solution A to solution B is 1.2:1, and the flow rate of solution A is 500 mL / min. At the same time, pump solution C to maintain the pH at 10-10.4.

[0109] Step S5: Dehydration, washing, and drying

[0110] After the reaction was completed, the wet material was obtained by washing, centrifugation and drying, and then dried in an oven at 120℃ to obtain manganese hydroxyoxide.

[0111] Example 5

[0112] Step S1, preparation of manganese source solution:

[0113] Manganese sulfate was dissolved in deionized water to prepare a 50L manganese sulfate solution with a concentration of 1.5mol / L. The solution was then filtered to obtain solution A.

[0114] Step S2, Preparation of oxidant:

[0115] Prepare a hydrogen peroxide solution B with a volume of 5.62 L and a concentration of 8.9 mol / L.

[0116] Step S3, pH adjuster preparation:

[0117] Prepare a 10.8 mol / L sodium hydroxide solution C;

[0118] Step S4, synthesis reaction;

[0119] Add one-third of the volume of deionized water to the reactor, heat to 40°C, stir at 300 rpm, and introduce a small amount of NaOH to bring the pH to 10-10.4. Then, pump solutions A and B into the synthesis vessel. The molar flow rate ratio of solution A to solution B is 4:1, and the flow rate of solution A is 500 mL / min. At the same time, pump solution C to maintain the pH at 10-10.4.

[0120] Step S5: Dehydration, washing, and drying

[0121] After the reaction was completed, the wet material was obtained by washing, centrifugation and drying, and then dried in an oven at 120℃ to obtain manganese hydroxyoxide.

[0122] Example 6

[0123] Step S1, preparation of manganese source solution:

[0124] Manganese sulfate was dissolved in deionized water to prepare a 50L manganese sulfate solution with a concentration of 1.5mol / L. The solution was then filtered to obtain solution A.

[0125] Step S2, Preparation of oxidant:

[0126] Prepare a hydrogen peroxide solution B with a volume of 5.62 L and a concentration of 8.9 mol / L.

[0127] Step S3, pH adjuster preparation:

[0128] Prepare a 10.8 mol / L sodium hydroxide solution C;

[0129] Step S4, synthesis reaction;

[0130] Add 40% of the volume of deionized water to the reactor, heat to 40°C, stir at 300 rpm, and introduce a small amount of NaOH until the pH reaches 9.6-9.9. Then, pump solutions A and B into the synthesis vessel. The molar flow rate ratio of solution A to solution B is 2:1, and the flow rate of solution A is 200 mL / min. At the same time, pump solution C to maintain the pH at 9.6-9.9.

[0131] Step S5: Dehydration, washing, and drying

[0132] After the reaction was completed, the wet material was obtained by washing, centrifugation and drying, and then dried in an oven at 120℃ to obtain manganese hydroxyoxide.

[0133] Example 7

[0134] Step S1, preparation of manganese source solution:

[0135] Manganese sulfate was dissolved in deionized water to prepare a 50L manganese sulfate solution with a concentration of 1.5mol / L. The solution was then filtered to obtain solution A.

[0136] Step S2, Preparation of oxidant:

[0137] Prepare a hydrogen peroxide solution B with a volume of 5.62 L and a concentration of 8.9 mol / L.

[0138] Step S3, pH adjuster preparation:

[0139] Prepare a 10.8 mol / L sodium hydroxide solution C;

[0140] Step S4, synthesis reaction;

[0141] Add 40% of the volume of deionized water to the reactor, heat to 70℃, stir at 300 rpm, and introduce a small amount of NaOH until the pH reaches 9.6~9.9. Then, pump solutions A and B into the synthesis vessel. The molar flow rate ratio of solution A to solution B is 2:1, and the flow rate of solution A is 200 mL / min. At the same time, pump solution C to maintain the pH at 9.6~9.9.

[0142] Step S5: Dehydration, washing, and drying

[0143] After the reaction was completed, the wet material was obtained by washing, centrifugation and drying, and then dried in an oven at 120℃ to obtain manganese hydroxyoxide.

[0144] Example 8

[0145] Step S1, preparation of manganese source solution:

[0146] Manganese sulfate was dissolved in deionized water to prepare a 50L manganese sulfate solution with a concentration of 1.5mol / L. The solution was then filtered to obtain solution A.

[0147] Step S2, Preparation of oxidant:

[0148] Prepare a hydrogen peroxide solution B with a volume of 5.62 L and a concentration of 8.9 mol / L.

[0149] Step S3, pH adjuster preparation:

[0150] Prepare a 10.8 mol / L sodium hydroxide solution C;

[0151] Step S4, synthesis reaction;

[0152] Add one-third volume of deionized water to the reactor, heat to 40°C, stir at 300 rpm, and introduce a small amount of NaOH until the pH reaches 9.6-9.9. Then, pump solutions A and B into the synthesis reactor. The molar flow rate ratio of solution A to solution B is 2:1, and the flow rate of solution A is 500 mL / min. At the same time, pump solution C to maintain the pH at 9.6-9.9.

[0153] Step S5: Dehydration, washing, and drying

[0154] After the reaction was completed, the wet material was obtained by washing, centrifugation and drying, and then dried in an oven at 120℃ to obtain manganese hydroxyoxide.

[0155] Comparative Example 1

[0156] The only difference between this comparative example and Example 1 is that the pH of the reaction system was always controlled at 8.5±0.5 during the synthesis process in step S4.

[0157] Comparative Example 2

[0158] The only difference between this comparative example and Example 1 is that the pH of the reaction system was always controlled at 11±0.5 during the synthesis process in step S4.

[0159] Comparative Example 3

[0160] The only difference between this comparative example and Example 1 is that, in the synthesis process of step S4, the molar flow ratio of solution A to solution B is 0.8:1.

[0161] Comparative Example 4

[0162] The only difference between this comparative example and Example 1 is that, in the synthesis process of step S4, the molar flow ratio of solution A to solution B is 5:1.

[0163] Comparative Example 5

[0164] The only difference between this comparative example and Example 1 is that, during the synthesis process in step S4, the flow rate of solution A is 700 mL / min.

[0165] The XRD patterns of the products prepared in Examples 1-8 are as follows: Figure 1 As shown, the XRD patterns of the products prepared in Comparative Examples 1-5 are as follows. Figure 2 As shown, from Figure 1 and Figure 2 It can be seen that the products prepared in Examples 1-8 are pure phase β-MnOOH, while the products prepared in Comparative Examples 1-3 are manganese oxides, and the product prepared in Comparative Example 4 is Mn7O. 13 The mixed phase of +β-MnOOH, the product prepared in Comparative Example 5 is mainly β-MnOOH, and also contains some Mn3O4.

[0166] SEM images of the MnOOH prepared in Examples 1-8 are shown below. Figures 3-10 As shown, by Figures 3-10 It can be seen that the prepared β-MnOOH consists of three-dimensional network spherical or near-spherical secondary particles formed by the winding of ribbon-like primary particles. The primary particles are filamentous with small diameters, and the resulting secondary particles are loose and porous, exhibiting high activity. Furthermore, the specific surface area of ​​the β-MnOOH obtained in each embodiment was measured to be 50 m². 2 The primary ribbon-like particles have a diameter of 10~50nm and a particle size of 2~20μm. The S content is above 1000ppm.

[0167] SEM images of the products prepared in Comparative Examples 1-5 are shown below. Figures 11-15 As shown, from Figures 11-15 It can be seen that the obtained product has a relatively small morphological porosity and a denser internal structure.

[0168] Table 1. Mn, BET, and S content of products prepared in each example and comparative example.

[0169]

[0170] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A β-MnOOH, characterized in that, The β-MnOOH is a three-dimensional network of spherical or near-spherical secondary particles formed by the winding of ribbon-like primary particles. These secondary particles are loose and porous. The specific surface area of ​​the β-MnOOH is 50 m². 2 / g or more, the diameter of the ribbon-like primary particles is 10~50nm; the particle size of the secondary particles is 2~20μm.

2. The β-MnOOH as described in claim 1, characterized in that, The specific surface area of ​​the β-MnOOH is 50~100m². 2 / g; the Mn content of the β-MnOOH is 60~65wt.%; the sulfur content of the β-MnOOH is below 1000ppm.

3. A method for synthesizing β-MnOOH as described in claim 1 or 2, characterized in that, include: A divalent manganese source solution, an oxidant solution, and a pH adjuster solution are introduced concurrently into the bottom liquid of the reaction vessel, and the reaction is stirred. The flow rate of the manganese source solution is 100~600 mL / min. During the reaction, the pH of the system is maintained at 9.5~10.

4. After the reaction is completed, the solution is filtered, washed, and dried to obtain β-MnOOH. The molar amount of the oxidant introduced per unit time is 2~8 times the amount of manganese source introduced per unit time that is theoretically required to achieve oxidation.

4. The method for synthesizing β-MnOOH as described in claim 3, characterized in that, The pH of the bottom liquid in the reactor is 9.5~10.

4.

5. The method for synthesizing β-MnOOH as described in claim 3, characterized in that, The bottom liquid of the reaction vessel is prepared using water and a pH adjuster.

6. The method for synthesizing β-MnOOH as described in claim 3, characterized in that, The amount of the bottom liquid in the reactor is 20-40% of the volume of the reactor used to synthesize β-MnOOH.

7. The method for synthesizing β-MnOOH as described in claim 3, characterized in that, The divalent manganese source is one or more of manganese sulfate, manganese nitrate, manganese chloride, manganese oxalate, and manganese acetate.

8. The method for synthesizing β-MnOOH as described in claim 3, characterized in that, The molar concentration of the manganese source in the divalent manganese source solution is 0.2~2.0 mol / L; The oxidant is one or more of the following: hydrogen peroxide, ammonium persulfate, sodium persulfate, potassium persulfate, ozone, potassium permanganate, dichromic acid, chlorine, chloric acid, hypochlorous acid, chlorite, perchloric acid, hypoiodic acid, metaperiodic acid, bromic acid, hypobromic acid, perbromic acid, and ferrate. The concentration of the oxidant solution is 1~10 mol / L.

9. The method for synthesizing β-MnOOH as described in claim 3, characterized in that, The temperature of the stirring reaction is controlled at 30~80℃; the stirring reaction time is 1~8h.

10. The method for synthesizing β-MnOOH as described in claim 3, characterized in that, The stirring reaction was carried out in an air atmosphere.

11. The method for synthesizing β-MnOOH as described in claim 3, characterized in that, The pH adjuster is sodium hydroxide.

12. The method for synthesizing β-MnOOH as described in claim 3, characterized in that, The concentration of the pH adjuster solution is 0.5~5 mol / L.

13. The method for synthesizing β-MnOOH as described in claim 3, characterized in that, The flow rate of the manganese source solution is 200~500 mL / min.

14. The application of β-MnOOH as described in claim 1 or 2, or β-MnOOH prepared by the synthesis method described in any one of claims 3 to 13, as a precursor or catalyst for positive electrode materials.

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