Beta-MnOOH as well as synthesis method and application thereof

Abstract

The invention provides beta-MnOOH, the beta-MnOOH is a three-dimensional net-shaped spherical or sphere-like secondary particle formed by winding a ribbon-shaped primary particle, and the secondary particle is loose and porous; the beta-MnOOH has a specific surface area of 50 m2 / g or more. The beta-MnOOH is high in specific surface area and high in activity, and is an excellent manganese oxide precursor and catalyst. The invention also provides a preparation method of the beta-MnOOH, the beta-MnOOH is synthesized through a one-step liquid phase precipitation method, the synthesis efficiency is high, the synthesis temperature is low, the oxidation degree of manganese is controllable through process control, and the beta-MnOOH with stable valence state and excellent morphology is obtained. The preparation method is relatively high in process stability, simple in process, simple in equipment requirement, free of a complexing agent, relatively low in cost, capable of realizing large-scale production and easy to realize industrialization.

Description

Technical Field

[0001] The invention belongs to the technical field of manganese compounds, and specifically relates to a synthesis method and application of β-MnOOH. Background Art

[0002] Manganese oxyhydroxide is a very important compound of manganese. Due to its special physical and chemical properties, MnOOH has very important uses in catalysts, sensors, adsorbents, supercapacitors, lithium-ion and sodium-ion batteries, etc. At the same time, MnOOH is considered to be the simplest and most practical precursor for preparing manganese oxides. Manganese oxyhydroxide is divided into three crystal forms: α, β, and γ-MnOOH according to the different ways of internal atomic connection. Among them, α-MnOOH is an orthorhombic crystal, β-MnOOH is a hexagonal crystal, and γ-MnOOH is a manganite crystal. Both α-MnOOH and γ-MnOOH have tunnel-like structures, and β-MnOOH is a layered structure with an interlayer spacing of 0.46 nm. Because its layer plates are uncharged and there are no anions or cations between the layers, β-MnOOH is an electrically neutral layered compound. And β-MnOOH is a metastable state, while γ-MnOOH is the most stable. Under certain conditions, β-MnOOH can be transformed into γ-MnOOH.

[0003] Loose nano-scale β-MnOOH is an excellent cathode precursor material and can be used as a precursor for materials such as lithium manganese oxide or manganese phosphate. Nano-scale β-MnOOH with high specific surface area and low S content is beneficial to improving the crystallinity of cathode materials and electrochemical performance. β-MnOOH nanowires with high specific surface area contain free hydroxyl groups on their surface and can also be used as an excellent carrier to prepare nanocomposites, showing excellent catalytic performance.

[0004] At present, the synthesis of β-hydroxy manganese oxide is mostly carried out by hydrothermal method, which has high synthesis temperature and high cost, and is not conducive to industrial production; and the manganese source is mostly potassium permanganate, and the reducing agent is mostly organic molecules, which is environmentally friendly, has poor safety, and is easy to introduce impurities.

[0005] The patent document with publication number CN102531064A discloses a method for preparing ultrafine single crystal manganese oxyhydroxide nanowires, which uses potassium permanganate as a raw material, polyvinyl pyrrolidone (K30, KSO, etc.), sodium dodecyl sulfate and other organic molecules as reducing agents, and performs hydrothermal reaction at a temperature of 120-170°C in a closed reactor, and can prepare ultrafine single crystal manganese oxyhydroxide (MnOOH) nanowires with a diameter of about 100nm and different aspect ratios in large quantities. The method has a high reaction temperature, expensive raw material costs, poor reaction safety, and is not conducive to industrial production.

[0006] Patent document with publication number CN1831210A discloses a method for preparing multi-branched manganese hydroxide single crystal nanoflowers. The method uses potassium permanganate as an oxidant and polyethylene glycol as a reducing agent. A hydrothermal reaction is carried out at a temperature of 100-200°C in a closed reactor. By controlling the reaction temperature, reaction time and raw material ratio, multi-branched manganese hydroxide 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 the problems of too high reaction temperature, expensive raw material cost and poor safety. Summary of the invention

[0007] In response to the above technical problems, the present application provides a β-MnOOH and a preparation method and application thereof.

[0008] To achieve the above objectives, this application proposes the following technical solutions: In a first aspect, a β-MnOOH is provided, wherein the β-MnOOH is a three-dimensional mesh spherical or quasi-spherical secondary particle formed by winding a ribbon-like primary particle, the secondary particle is loose and porous, and the specific surface area of ​​the β-MnOOH is 50 m 2 / g or above.

[0009] Preferably, the specific surface area of ​​the β-MnOOH is 50-100 m 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-shaped primary particles is 10~50nm; the particle size of the secondary particles is 2~20μm.

[0010] In a second aspect, a method for synthesizing β-MnOOH is provided, comprising: A divalent manganese source solution, an oxidant solution and a pH adjuster solution are introduced into the bottom liquid of the reaction kettle in parallel for stirring reaction. The flow rate of the manganese source solution is 100-600 mL / min. The pH of the system is maintained at 9.5-10.5 during the reaction. After the reaction is completed, β-MnOOH is obtained by filtering, washing and drying.

[0011] Preferably, the pH of the reactor bottom liquid is 9.5-10.5; preferably, the reactor bottom liquid is prepared with water and a pH regulator; preferably, the amount of the reactor bottom liquid is 20-40% of the volume of the synthesis reactor for synthesizing β-MnOOH.

[0012] 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.

[0013] Preferably, the temperature of the stirring reaction is controlled at 30-80° C.; and the time of the stirring reaction is 1-8 h.

[0014] Preferably, the reaction is carried out under air atmosphere.

[0015] Preferably, 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, chlorous acid, perchloric acid, hypoiodous acid, metaperiodic acid, bromic acid, hypobromous acid, perbromic acid, and ferrate.

[0016] Preferably, the concentration of the oxidant solution is 1-10 mol / L.

[0017] Preferably, the pH regulator is ammonia water and / or sodium hydroxide; preferably, the concentration of the pH regulator solution is 0.5-5 mol / L.

[0018] Preferably, the flow rate of the oxidant solution and the flow rate of the manganese source solution are determined according to a molar ratio of the oxidant to the manganese source introduced per unit time of 1 to 4:1.

[0019] Preferably, the flow rate of the manganese source solution is 200-500 mL / min.

[0020] In a third aspect, there is also provided the use of the aforementioned β-MnOOH or the β-MnOOH prepared by the aforementioned preparation method as a cathode material precursor or catalyst.

[0021] Compared with the prior art, one or more of the above technical solutions can achieve at least one of the following beneficial effects: The provided β-MnOOH is a three-dimensional mesh spherical or quasi-spherical secondary particle formed by winding ribbon-like primary particles. It has a high specific surface area and high activity, and is an excellent manganese oxide precursor and catalyst.

[0022] β-MnOOH is synthesized by a one-step liquid phase precipitation method, with high synthesis efficiency, low synthesis temperature, and controllable degree of oxidation of manganese through process control, to obtain trivalent β-MnOOH with stable valence state, high process stability, simple process, no need for complexing agent, simple equipment requirements, low cost, large-scale production, and easy industrialization. The synthesized β-MnOOH has high purity, high BET, low S content, low impurity content, and high powder activity, and can be used as an excellent manganese oxide precursor and catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 : XRD patterns of MnOOH prepared in Examples 1 to 8.

[0025] Figure 2 The XRD diagram of MnOOH prepared in Comparative Examples 1-5.

[0026] Figure 3 These are SEM images of MnOOH prepared in Example 1 at different magnifications.

[0027] Figure 4 These are SEM images of MnOOH prepared in Example 2 at different magnifications.

[0028] Figure 5 These are SEM images of MnOOH prepared in Example 3 at different magnifications.

[0029] Figure 6 These are SEM images of MnOOH prepared in Example 4 at different magnifications.

[0030] Figure 7 These are SEM images of MnOOH prepared in Example 5 at different magnifications.

[0031] Figure 8 These are SEM images of MnOOH prepared in Example 6 at different magnifications.

[0032] Fig. 9 These are SEM images of MnOOH prepared in Example 7 at different magnifications.

[0033] Fig.10 These are SEM images of MnOOH prepared in Example 8 at different magnifications.

[0034] Fig.11 These are SEM images of MnOOH prepared in Comparative Example 1 at different magnifications.

[0035] Fig.12 These are SEM images of MnOOH prepared in Comparative Example 2 at different magnifications.

[0036] Fig.13 These are SEM images of MnOOH prepared in Comparative Example 3 at different magnifications.

[0037] Fig.14 These are SEM images of MnOOH prepared in Comparative Example 4 at different magnifications.

[0038] Fig.15 These are SEM images of MnOOH prepared in Comparative Example 5 at different magnifications. DETAILED DESCRIPTION

[0039] The present invention provides a β-MnOOH, wherein the β-MnOOH is a three-dimensional mesh spherical or quasi-spherical secondary particle formed by winding a ribbon-like primary particle, and the secondary particle is loose and porous; the specific surface area of ​​the β-MnOOH is 50m 2 / g or more. First, pure phase β-MnOOH is a metastable state with large free energy and high material surface activity. As a precursor of positive electrode material, it is beneficial to the embedding of Li and improve the electrochemical activity. Secondly, β-MnOOH of this morphology has the characteristics of high specific surface area and high activity. As a precursor of positive electrode material, it is beneficial to the embedding of Li and improve the electrochemical activity. In addition, the ribbon-shaped primary particles are not conducive to the entrainment of impure sulfur, so the impurity sulfur content is low.

[0040] In some preferred embodiments, the specific surface area of ​​the β-MnOOH is 50-100 m 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.

[0041] 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.

[0042] In some preferred embodiments, the sulfur content of the β-MnOOH is below 1000 ppm, more preferably below 800 ppm, and further preferably below 700 ppm; on the one hand, a lower impurity content is beneficial to improving material properties, and on the other hand, a lower impurity sulfur content leads to smaller surface primary particles, and the material formed by smaller primary particles has higher activity and specific surface area.

[0043] In some preferred embodiments, the diameter of the ribbon-shaped primary particles is 10~50nm, for example, 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, 50nm, etc.; the particle size of the secondary particles is 2~20μm, for example, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, etc.

[0044] Some embodiments of the present application provide a method for synthesizing β-MnOOH, comprising: A divalent manganese source solution, an oxidant solution and a pH adjuster solution are introduced into the bottom liquid of the reaction kettle in parallel for stirring 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 (for example, 9.5, 9.8, 10, 10.2, 10.5, etc.). After the reaction is completed, β-MnOOH is obtained by filtering, washing and drying.

[0045] In some preferred embodiments, the pH of the reaction kettle bottom liquid is 9.5-10.5, for example, 9.5, 9.8, 10, 10.2, 10.5, etc.; the reaction kettle bottom liquid is prepared with water and a pH regulator; the amount of the reaction kettle bottom liquid is 20-40% of the volume of the synthesis kettle for synthesizing β-MnOOH, for example, 20%, 25%, 30%, 35%, 40%, etc.

[0046] In some preferred embodiments, the reaction is carried out under air atmosphere.

[0047] In some preferred embodiments, the divalent manganese source is one or more of manganese sulfate, manganese nitrate, manganese chloride, manganese oxalate, and manganese acetate.

[0048] In some preferred embodiments, the molar concentration of the manganese source in the manganese source solution is 0.2-2.0 mol / L.

[0049] 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, chlorous acid, perchloric acid, hypoiodous acid, metaperiodic acid, bromic acid, hypobromous acid, perbromic acid, and ferrate.

[0050] 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.

[0051] 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.

[0052] In some preferred embodiments, the temperature of the stirring reaction is controlled to be 30-80°C, for example, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, etc.; the time of the stirring reaction is 1-8h, for example, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, etc.

[0053] In some preferred embodiments, the molar amount of the oxidant introduced per unit time is 2 to 8 times the amount theoretically required to achieve oxidation of the manganese source introduced per unit time, for example, 2 times, 3 times, 4 times, 5 times, 6 times, 7 times, 8 times, etc.

[0054] In some preferred embodiments, the flow rate of the manganese source solution is 200-500 mL / min, for example, 200 mL / min, 250 mL / min, 300 mL / min, 350 mL / min, 400 mL / min, 450 mL / min, 500 mL / min, etc.

[0055] In some embodiments, the manganese source solution is obtained by dissolving a manganese source in deionized water.

[0056] In some embodiments, the pH adjuster solution is obtained by dissolving the pH adjuster in water and filtering.

[0057] In some embodiments, the oxidant solution is obtained by dissolving the oxidant in water and filtering.

[0058] In some preferred embodiments, the drying is oven drying; the oven drying temperature is 80-150°C.

[0059] In various embodiments, the water is deionized water.

[0060] Some embodiments of the present application also provide a β-MnOOH, which is synthesized using the aforementioned synthesis method.

[0061] The present invention also provides the use of the aforementioned β-MnOOH or the β-MnOOH prepared by the aforementioned preparation method as a cathode material precursor or catalyst.

[0062] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings and preferred embodiments of the specification, but the protection scope of the present invention is not limited to the following specific embodiments.

[0063] Particle size distribution test: Malvern 3000 particle size analyzer.

[0064] BET test: specific surface area tester, model BSD-BET400, manufacturer is Best Instrument Technology (Beijing) Co., Ltd.

[0065] Vibration test: Vibration density meter, model BT-313, manufacturer is Dandong Better Instrument Co., Ltd.

[0066] Mn, Fe, P, S element content test method: ICP.

[0067] Example 1 Step S1, preparation of manganese source solution: Manganese sulfate was dissolved in deionized water to prepare a manganese sulfate solution with a volume of 50 L and a concentration of 1.5 mol / L, and the solution A was obtained by filtering.

[0068] Step S2, oxidant preparation: Prepare hydrogen peroxide solution B with a volume of 5.62 L and a concentration of 8.9 mol / L.

[0069] Step S3, preparation of pH adjusting agent: Prepare 10.8 mol / L sodium hydroxide solution C; Step S4, synthesis reaction; Add one third of the reactor volume of deionized water into the reactor, heat to 40°C, stir at 300 rpm, introduce a small amount of NaOH to pH = 9.6-9.9, then pump solution A and solution B into the synthesis reactor, the molar flow ratio of solution A to solution B is 2:1, the flow rate of solution A is 200 mL / min, and simultaneously pump solution C to maintain pH = 9.6-9.9.

[0070] Step S5, dehydration, washing and drying After the reaction is completed, the wet material is obtained by washing, centrifugation and drying, and then dried in an oven at 120° C. to obtain manganese oxyhydroxide.

[0071] Example 2 Step S1, preparation of manganese source solution: Manganese sulfate was dissolved in deionized water to prepare a manganese sulfate solution with a volume of 50 L and a concentration of 1.5 mol / L, and the solution A was obtained by filtering.

[0072] Step S2, oxidant preparation: Prepare hydrogen peroxide solution B with a volume of 10.11 L and a concentration of 8.9 mol / L.

[0073] Step S3, preparation of pH adjusting agent: Prepare 10.8 mol / L sodium hydroxide solution C; Step S4, synthesis reaction; Add one third of the reactor volume of deionized water into the reactor, heat to 40°C, stir at 300 rpm, introduce a small amount of NaOH to pH = 10-10.4, then pump solution A and solution B into the synthesis reactor, the molar flow ratio of solution A to solution B is 1.2:1, the flow rate of solution A is 200 mL / min, and simultaneously pump solution C to maintain pH = 10-10.4.

[0074] Example 3 Step S1, preparation of manganese source solution: Manganese sulfate was dissolved in deionized water to prepare a manganese sulfate solution with a volume of 50 L and a concentration of 1.5 mol / L, and the solution A was obtained by filtering.

[0075] Step S2, oxidant preparation: Prepare hydrogen peroxide solution B with a volume of 10.11 L and a concentration of 8.9 mol / L.

[0076] Step S3, preparation of pH adjusting agent: Prepare 10.8 mol / L sodium hydroxide solution C; Step S4, synthesis reaction; Add one third of the reactor volume of deionized water into the reactor, heat to 40°C, stir at 500 rpm, introduce a small amount of NaOH to pH = 10-10.4, then pump solution A and solution B into the synthesis reactor, the molar flow ratio of solution A to solution B is 1.2:1, the flow rate of solution A is 200 mL / min, and simultaneously pump solution C to maintain pH = 10-10.4.

[0077] Example 4 Step S1, preparation of manganese source solution: Manganese sulfate was dissolved in deionized water to prepare a manganese sulfate solution with a volume of 50 L and a concentration of 1.5 mol / L, and the solution A was obtained by filtering.

[0078] Step S2, oxidant preparation: Prepare hydrogen peroxide solution B with a volume of 5.62 L and a concentration of 8.9 mol / L.

[0079] Step S3, preparation of pH adjusting agent: Prepare 10.8 mol / L sodium hydroxide solution C; Step S4, synthesis reaction; Add deionized water, one third of the reactor volume, into the reactor, heat to 40°C, stir at 300 rpm, introduce a small amount of NaOH to pH = 10-10.4, and then pump solution A and solution B into the synthesis reactor. The molar flow ratio of solution A to solution B is 1.2:1, the flow rate of solution A is 500 mL / min, and solution C is pumped in at the same time to maintain pH = 10-10.4.

[0080] Step S5, dehydration, washing and drying After the reaction is completed, the wet material is obtained by washing, centrifugation and drying, and then dried in an oven at 120° C. to obtain manganese oxyhydroxide.

[0081] Example 5 Step S1, preparation of manganese source solution: Manganese sulfate was dissolved in deionized water to prepare a manganese sulfate solution with a volume of 50 L and a concentration of 1.5 mol / L, and the solution A was obtained by filtering.

[0082] Step S2, oxidant preparation: Prepare hydrogen peroxide solution B with a volume of 5.62 L and a concentration of 8.9 mol / L.

[0083] Step S3, preparation of pH adjusting agent: Prepare 10.8 mol / L sodium hydroxide solution C; Step S4, synthesis reaction; Add one third of the reactor volume of deionized water into the reactor, heat to 40°C, stir at 300 rpm, introduce a small amount of NaOH to pH = 10-10.4, then pump solution A and solution B into the synthesis reactor, the molar flow ratio of solution A to solution B is 4:1, the flow rate of solution A is 500 mL / min, and simultaneously pump solution C to maintain pH = 10-10.4.

[0084] Step S5, dehydration, washing and drying After the reaction is completed, the wet material is obtained by washing, centrifugation and drying, and then dried in an oven at 120° C. to obtain manganese oxyhydroxide.

[0085] Example 6 Step S1, preparation of manganese source solution: Manganese sulfate was dissolved in deionized water to prepare a manganese sulfate solution with a volume of 50 L and a concentration of 1.5 mol / L, and the solution A was obtained by filtering.

[0086] Step S2, oxidant preparation: Prepare hydrogen peroxide solution B with a volume of 5.62 L and a concentration of 8.9 mol / L.

[0087] Step S3, preparation of pH adjusting agent: Prepare 10.8 mol / L sodium hydroxide solution C; Step S4, synthesis reaction; Deionized water accounting for 40% of the reactor volume was added into the reactor, the temperature was raised to 40°C, the stirring speed was 300 rpm, a small amount of NaOH was introduced until the pH was 9.6-9.9, and then solutions A and B were pumped into the synthesis reactor. The molar flow ratio of solution A to solution B was 2:1, the flow rate of solution A was 200 mL / min, and solution C was pumped in at the same time to maintain the pH at 9.6-9.9.

[0088] Step S5, dehydration, washing and drying After the reaction is completed, the wet material is obtained by washing, centrifugation and drying, and then dried in an oven at 120° C. to obtain manganese oxyhydroxide.

[0089] Example 7 Step S1, preparation of manganese source solution: Manganese sulfate was dissolved in deionized water to prepare a manganese sulfate solution with a volume of 50 L and a concentration of 1.5 mol / L, and the solution A was obtained by filtering.

[0090] Step S2, oxidant preparation: Prepare hydrogen peroxide solution B with a volume of 5.62 L and a concentration of 8.9 mol / L.

[0091] Step S3, preparation of pH adjusting agent: Prepare 10.8 mol / L sodium hydroxide solution C; Step S4, synthesis reaction; Deionized water accounting for 40% of the reactor volume was added into the reactor, the temperature was raised to 70°C, the stirring speed was 300 rpm, a small amount of NaOH was introduced until the pH was 9.6-9.9, and then solutions A and B were pumped into the synthesis reactor. The molar flow ratio of solution A to solution B was 2:1, the flow rate of solution A was 200 mL / min, and solution C was pumped in at the same time to maintain the pH at 9.6-9.9.

[0092] Step S5, dehydration, washing and drying After the reaction is completed, the wet material is obtained by washing, centrifugation and drying, and then dried in an oven at 120° C. to obtain manganese oxyhydroxide.

[0093] Example 8 Step S1, preparation of manganese source solution: Manganese sulfate was dissolved in deionized water to prepare a manganese sulfate solution with a volume of 50 L and a concentration of 1.5 mol / L, and the solution A was obtained by filtering.

[0094] Step S2, oxidant preparation: Prepare hydrogen peroxide solution B with a volume of 5.62 L and a concentration of 8.9 mol / L.

[0095] Step S3, preparation of pH adjusting agent: Prepare 10.8 mol / L sodium hydroxide solution C; Step S4, synthesis reaction; Add deionized water, one third of the reactor volume, into the reactor, heat to 40°C, stir at 300 rpm, introduce a small amount of NaOH to pH = 9.6-9.9, and then pump solution A and solution B into the synthesis reactor. The molar flow ratio of solution A to solution B is 2:1, the flow rate of solution A is 500 mL / min, and solution C is pumped in at the same time to maintain pH = 9.6-9.9.

[0096] Step S5, dehydration, washing and drying After the reaction is completed, the wet material is obtained by washing, centrifugation and drying, and then dried in an oven at 120° C. to obtain manganese oxyhydroxide.

[0097] Comparative Example 1 The only difference between this comparative example and Example 1 is that during the synthesis process of step S4, the pH of the reaction system is always controlled at 8.5±0.5.

[0098] Comparative Example 2 The only difference between this comparative example and Example 1 is that during the synthesis process of step S4, the pH of the reaction system is always controlled at 11±0.5.

[0099] Comparative Example 3 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.

[0100] Comparative Example 4 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.

[0101] Comparative Example 5 The difference between this comparative example and Example 1 is that during the synthesis process of step S4, the flow rate of solution A is 700 mL / min.

[0102] The XRD patterns of the products prepared in Examples 1 to 8 are as follows: Figure 1 As shown, the XRD patterns of the products prepared in Comparative Examples 1 to 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 to 8 are pure phase β-MnOOH, while the products prepared in Comparative Examples 1 to 3 are manganese oxides, and the product prepared in Comparative Example 4 is Mn7O 13 +β-MnOOH mixed phase, the product prepared in Comparative Example 5 is mainly β-MnOOH and also contains part of Mn3O4.

[0103] The SEM images of MnOOH prepared in Examples 1 to 8 are as follows: Figures 3 to 10 As shown by Figures 3 to 10 It can be seen that the prepared β-MnOOH is a three-dimensional mesh spherical or quasi-spherical secondary particle formed by winding a ribbon-like primary particle. The primary particle is filamentous and has a small diameter. The secondary particles are loose and porous, and have high activity. The specific surface area of ​​the β-MnOOH obtained in each embodiment is 50m 2 / g or more, the S content is below 1000ppm, the diameter of the ribbon-shaped primary particles is 10-50nm; the particle size of the secondary particles is 2-20μm.

[0104] The SEM images of the products prepared in Comparative Examples 1 to 5 are as follows: Figures 11 to 15 As shown, from Figures 11 to 15 It can be seen that the morphology of the obtained product is relatively loose and the interior is denser.

[0105] Table 1 Mn content, BET and S content of the products prepared in various examples and comparative examples The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A β-MnOOH, characterized in that: The β-MnOOH is a three-dimensional mesh spherical or quasi-spherical secondary particle formed by winding ribbon-like primary particles. The secondary particles are loose and porous. The specific surface area of ​​the β-MnOOH is 50 m 2 / g or above.

2. The β-MnOOH according to claim 1, characterized in that The specific surface area of ​​the β-MnOOH is 50-100 m 2 / g; the Mn content of the β-MnOOH is 60~65wt.%; the sulfur content of the β-MnOOH is below 1000ppm; the diameter of the ribbon-shaped primary particles is 10~50nm; the particle size of the secondary particles is 2~20μm.

3. A method for synthesizing β-MnOOH, characterized in that: include: A divalent manganese source solution, an oxidant solution and a pH adjuster solution are introduced into the bottom liquid of the reaction kettle in parallel for stirring reaction. The flow rate of the manganese source solution is 100-600 mL / min. The pH of the system is maintained at 9.5-10.5 during the reaction. After the reaction is completed, β-MnOOH is obtained by filtering, washing and drying.

4. The method for synthesizing β-MnOOH according to claim 3, characterized in that: The pH of the reactor bottom liquid is 9.5-10.5; preferably, the reactor bottom liquid is prepared by water and a pH regulator; preferably, the amount of the reactor bottom liquid is 20-40% of the volume of the synthesis reactor for synthesizing β-MnOOH.

5. The method for synthesizing β-MnOOH according to 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; preferably, 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 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, chlorous acid, perchloric acid, hypoiodous acid, metaperiodic acid, bromic acid, hypobromous acid, perbromic acid, and ferrate; The concentration of the oxidant solution is 1-10 mol / L.

6. The method for synthesizing β-MnOOH according to claim 3, characterized in that: The temperature of the stirring reaction is controlled to be 30-80°C; the time of the stirring reaction is 1-8h; Preferably, the stirring reaction is carried out under air atmosphere.

7. The method for synthesizing β-MnOOH according to claim 3, characterized in that: The pH adjuster is sodium hydroxide; preferably, the concentration of the pH adjuster solution is 0.5-5 mol / L.

8. The method for synthesizing β-MnOOH according to claim 3, characterized in that: The molar amount of the oxidant introduced per unit time is 2 to 8 times the amount theoretically required to achieve oxidation of the manganese source introduced per unit time.

9. The method for synthesizing β-MnOOH according to claim 3, characterized in that: The flow rate of the manganese source solution is 200-500 mL / min.

10. Use of the β-MnOOH according to claim 1 or 2 or the β-MnOOH prepared by the preparation method according to any one of claims 3 to 9 as a cathode material precursor or catalyst.

Images